Patent Publication Number: US-2021175771-A1

Title: Rotary electric machine unit

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of International Patent Application No. PCT/JP2019/022083 filed on Jun. 4, 2019, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2018-139475 filed on Jul. 25, 2018. The entire disclosures of all of the above applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a rotary electric machine unit. 
     BACKGROUND 
     For example, a rotary electric machine unit has an electric motor as a rotary electric machine, an electric power conversion device that converts an electric power to be supplied to the electric motor from DC power to AC power, and a cooling device that cools the electric motor and the electric power conversion device. The cooling device may be formed into a tubular shape as a whole, and the electric motor may be accommodated in an internal space of the cooling device. The electric power conversion device may be packaged into a rectangular parallelepiped shape and be attached to an outer peripheral surface of the cooling device. The cooling device may cool the outer peripheral surface of the electric motor and the contact surface with the electric power conversion device. 
     SUMMARY 
     The present disclosure describes a rotary electric machine unit including a rotary electric machine, and an electric power conversion device having a plurality of power modules. The rotary electric machine includes a stator, a rotor, and a housing. The housing includes a housing flow path through which a refrigerant flows. The power modules of the electric power conversion device and the rotary electric machine are configured to be cooled by the refrigerant. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. 
         FIG. 1  is an equivalent circuit diagram showing a drive system to which an electric power conversion device according to a first embodiment is applied. 
         FIG. 2  is a perspective view showing a semiconductor device. 
         FIG. 3  is a cross-sectional view taken along a line III-Ill in  FIG. 2 . 
         FIG. 4  is a plan view of the semiconductor device when viewed from a main terminal side. 
         FIG. 5  is a perspective view of the semiconductor device in which a sealing resin body is deleted from the view of  FIG. 2 . 
         FIG. 6  is a perspective view of a lead frame before an unnecessary portion is cut off. 
         FIG. 7  is a plan view showing a positional relationship between an IGBT and main terminals. 
         FIG. 8  is a perspective view showing another example of the semiconductor device. 
         FIG. 9  is a perspective view showing another example of the semiconductor device. 
         FIG. 10  is a perspective view showing another example of the semiconductor device. 
         FIG. 11  is a diagram showing a magnetic analysis result of the total inductance of the main terminals. 
         FIG. 12  is a perspective view showing another example of the semiconductor device. 
         FIG. 13  is a plan view showing another example of the semiconductor device and corresponds to  FIG. 7 . 
         FIG. 14  is a plan view showing another example of the semiconductor device and corresponds to  FIG. 7 . 
         FIG. 15  is a plan view showing another example of the semiconductor device and corresponds to  FIG. 7 . 
         FIG. 16  is a plan view showing another example of the semiconductor device and corresponds to  FIG. 7 . 
         FIG. 17  is a cross-sectional view showing another example of the semiconductor device and corresponds to  FIG. 3 . 
         FIG. 18  is a cross sectional view taken along a line XVIII-XVIII in  FIG. 17 . 
         FIG. 19  is a cross-sectional view showing another example of the semiconductor device. 
         FIG. 20  is a plan view showing a positional relationship between the IGBT and the main terminals and correspond to  FIG. 7 . 
         FIG. 21  is a plan view showing a power module. 
         FIG. 22  is a cross-sectional view taken along a line XXII-XXII in  FIG. 21 . 
         FIG. 23  is a plan view when the power module shown in  FIG. 21  is viewed from a back side. 
         FIG. 24  is a plan view when the power module shown in  FIG. 21  is viewed in a direction A. 
         FIG. 25  is a plan view when the power module shown in  FIG. 21  is viewed in a direction B; 
         FIG. 26  is a plan view when the power module shown in  FIG. 21  is viewed in a direction C. 
         FIG. 27  is a view for illustrating connections of the semiconductor device, a smoothing capacitor, and each bus bar. 
         FIG. 28  is an equivalent circuit diagram including a wiring parasitic inductance. 
         FIG. 29  is a schematic diagram showing another example of  FIG. 27 . 
         FIG. 30  is a diagram showing a schematic configuration of a rotary electric machine. 
         FIG. 31  is a cross-sectional view taken along a line XXXI-XXXI in  FIG. 30 . 
         FIG. 32  is a perspective view of a rotary electric machine unit. 
         FIG. 33  is a view of a motor generator when viewed in a radial direction. 
         FIG. 34  is a diagram for explaining a configuration of a housing flow path. 
         FIG. 35  is a schematic cross-sectional view showing a cooling structure. 
         FIG. 36  is a schematic cross-sectional view showing another example of the housing flow path for the cooling structure. 
         FIG. 37  is a schematic cross-sectional view showing another example of the configuration of a power module for the cooling structure. 
         FIG. 38  is a schematic cross-sectional view showing another example of the position of a drive substrate for the cooling structure. 
         FIG. 39  is a schematic cross-sectional view showing a cooling structure of a motor unit according to a second embodiment. 
         FIG. 40  is a schematic cross-sectional view showing another example of a position of a drive substrate for the cooling structure. 
         FIG. 41  is a schematic cross-sectional view showing another example of the positions of a capacitor and the drive substrate for the cooling structure. 
         FIG. 42  is a schematic cross-sectional view showing a cooling structure of a motor unit according to a third embodiment. 
         FIG. 43  is a cross-sectional view of a housing taken in a direction orthogonal to an axial direction in a motor unit according to a fourth embodiment. 
         FIG. 44  is a cross-sectional view of a housing around power modules in a direction orthogonal to a circumferential direction. 
         FIG. 45  is a schematic plan view showing another example of arrangement of power modules in a housing flow path. 
         FIG. 46  is a cross-sectional view of a housing taken in a direction orthogonal to an axial direction in a motor unit according to a fifth embodiment. 
         FIG. 47  is a cross-sectional view of a housing around power modules in a direction orthogonal to a circumferential direction. 
     
    
    
     DETAILED DESCRIPTION 
     A rotary electric machine unit, for example, has an electric motor as a rotary electric machine, an electric power conversion device that converts an electric power to be supplied to the electric motor from DC power to AC power, and a cooling device that cools the electric motor and the electric power conversion device. The cooling device may be formed into a tubular shape as a whole, and the electric motor may be accommodated in an internal space of the cooling device. The electric power conversion device may be packaged into a rectangular parallelepiped shape and be attached to an outer peripheral surface of the cooling device. The cooling device may cool the outer peripheral surface of the electric motor and the contact surface with the electric power conversion device. 
     In such a rotary electric machine unit, however, when heat is generated due to its driving, it is considered that the temperature of each part is not uniform, and hence there are a part where the temperature readily rises and a part where the temperature does not readily rise. In an electric power conversion device, therefore, in a configuration where a surface of a package of the electric power conversion device is simply attached to the outer peripheral surface of a cooling device, the cooling effect is likely to be insufficient in the part where the temperature readily rises. Further, in the rotary electric machine, since the outer peripheral surface is covered with the electric power conversion device, the cooling effect is insufficient. As such, there is a concern that the cooling effects of the rotary electric machine and the electric power conversion device constituting the rotary electric machine unit are insufficient. 
     A rotary electric machine unit according to a first aspect includes: a rotary electric machine that has an annular stator, a rotor disposed on an inner side of the stator, and a housing accommodating the stator and the rotor therein; and an electric power conversion device that converts an electric power to be supplied to the rotary electric machine from DC power to AC power. The electric power conversion device includes a plurality of power modules having semiconductor devices constituting upper and lower arm circuits and being attached to the housing individually from each other. The housing includes: a housing flow path through which a refrigerant flows; a first cooling part that extends along an outer peripheral surface of the stator and cools the rotor with the refrigerant flowing in the housing flow path; and a second cooling part that cools the power modules with the refrigerant flowing in the housing flow path. The plurality of power modules are arranged along the second cooling part in a circumferential direction about a centerline of the rotor. 
     According to the first aspect, since the first cooling part of the housing extends along the outer peripheral surface of the stator, the first cooling part can cool the stator in a wider range. Further, since the plurality of power modules, which are separately attached to the housing, are arranged along the second cooling part of the housing, the plurality of power modules can be individually cooled by the second cooling part. In addition, each of power modules can be individually arranged at a location or in a position so that the cooling effect by the second cooling unit is enhanced. Therefore, the cooling effect of the power module by the second cooling unit is readily enhanced. Accordingly, the cooling effect can be enhanced for both of the rotary electric machine and the electric power conversion device. 
     Moreover, the plurality of power modules are arranged in the circumferential direction about the centerline. A direction in which the center line extends is referred to as an axial direction. Each of the power modules can be arranged adjacent to one end of the housing in the axial direction. Therefore, in a structure in which connection terminals of the stator are arranged adjacent to an end of the rotary electric machine, each power module can be arranged at a position as close as possible to the connection terminals. In such a case, since electric wirings connecting the power module and the rotary electric machine can be shortened as much as possible, the heat generated from the electric wirings can be reduced. In this way, since the heat generated in the rotary electric machine unit is reduced, the cooling effect in the rotary electric machine unit can be further enhanced. 
     A rotary electric machine unit according to a second aspect includes: a rotary electric machine that has an annular stator, a rotor disposed on an inner side of the stator, and a housing accommodating the stator and the rotor therein; and an electric power conversion device that converts an electric power to be supplied to the rotary electric machine from DC power to AC power. The housing includes: a housing flow path that extends along an outer peripheral surface of the stator and allows a refrigerant to flow therein; and a housing cooling part that cools the rotor with the refrigerant flowing through the housing flow path. The electric power conversion device includes a plurality of power modules that include semiconductor devices constituting upper and lower arm circuits, are attached to the housing individually from each other and along the housing flow path, and are oriented such that one surface of each semiconductor device is adjacent to the housing. The electric power conversion deice further includes a module cooling unit that includes a module flow path being in communication with the housing flow path and extending along a rear surface of each semiconductor device opposite to the one surface, and cools the semiconductor devices with the refrigerant flowing in the module flow path. 
     According to the second aspect, since the housing cooling part is extended along the outer peripheral surface of the stator, the stator can be cooled by the housing cooling part in a wider range, in a similar manner to the first cooling part of the first aspect. 
     In addition, in each of the power modules, the module flow path of the module cooling unit is extended along the rear surface of the semiconductor device. Therefore, the semiconductor device can be directly cooled by the module cooling part. In this way, a cooling operation of the semiconductor device by the module cooling part is performed inside of the power module. Therefore, the entirety of the power module can be cooled from its inside together with the semiconductor device. As such, the cooling effect can be enhanced for both of the rotary electric machine and the electric power conversion device, in the similar manner to the first aspect as described above. 
     A rotary electric machine according to a third aspect includes: a rotary electric machine that has an annular stator, a rotor disposed on an inner side of the stator, and a housing accommodating the stator and the rotor therein; and an power conversion device that converts an electric power to be supplied to the rotary electric machine from DC power to AC power. The housing includes: a housing flow path that extends along an outer peripheral surface of the stator and allows a refrigerant to flow therein; and a housing cooling part that cools the rotor with the refrigerant flowing through the housing flow path. The electric power conversion device includes a plurality of power modules that include semiconductor devices constituting upper and lower arm circuits. Each of the semiconductor devices has one surface and a rear surface opposite to the one surface in a thickness direction. The plurality of power modules are attached to the housing individually from each other and arranged along the housing flow path such that the housing flow path is located on both the one surface and the rear surface of each semiconductor device, and the semiconductor device is cooled with the refrigerant flowing in the housing flow path. 
     According to the third aspect, since the housing cooling part is extended along the outer peripheral surface of the stator, the stator can be cooled by the housing cooling part in a wider range, in a similar manner to the first cooling part of the first aspect. In addition, the housing flow path is located to face both of the one surface and the rear surface of the semiconductor device, the power module can be cooled from both sides by the refrigerant flowing in the housing flow path. As such, the cooling effect of the power modules by the refrigerant is readily enhanced. As such, the cooling effect can be enhanced for both of the rotary electric machine and the electric power conversion device, in the similar manner to the first aspect as described above. 
     Multiple embodiments will be described with reference to the drawings. In the multiple embodiments, functionally and/or structurally corresponding parts are given the same reference numerals. Hereinafter, a thickness direction of a semiconductor device  20  is referred to as a Z direction, and a direction that is orthogonal to the Z direction and along which semiconductor devices  200  in one power module  110  are arranged is referred to as an X direction. A direction orthogonal to both of the Z direction and the X direction is referred to as a Y direction. Unless otherwise specified, a shape along an XY plane including the X direction and the Y direction is referred to as a planar shape. 
     First Embodiment 
     An electric power conversion device and a motor unit of the present embodiment can be, for example, employed to a vehicle, such as an electric vehicle (EV) or a hybrid vehicle (HV). Hereinafter, an example in which the electric power conversion device and the motor unit are employed to the hybrid vehicle will be described. 
     (Drive System) 
     First, a schematic configuration of a drive system to which an electric power conversion device and a motor unit are applied will be described with reference to  FIG. 1 . 
     As shown in  FIG. 1 , a drive system  1  of a vehicle includes a DC power supply  2 , a motor generator  3 , an electric power conversion device  5  that converts electric power between the DC power supply  2  and the motor generator  3 . 
     The DC power supply  2  is a secondary battery capable of charging and discharging, such as a lithium ion battery or a nickel hydrogen battery. The motor generator  3  is a three-phase alternating current type rotary electric machine. The motor generator  3  is mounted on the vehicle together with an engine, as a traveling drive source. The motor generator  3  may function as an electric generator (alternator) that generates an electric power as being driven by an engine (not shown) and as an electric motor (starter) that starts the engine. The motor generator  3  may also function as the electric generator at the time of regeneration. 
     The electric power conversion device  5  includes an inverter  7 , a control circuit  9 , a smoothing capacitor C 2 , and a filter capacitor. The inverter  7  is a power conversion unit. The inverter  7  is a DC-to-AC conversion unit that converts a DC voltage into an AC voltage. The inverter  7  includes parallel circuits  11  each having an upper and lower arm circuit  10  and a capacitor C 1 . 
     The upper and lower arm circuit  10  includes switching elements Q 1  and Q 2  and diodes D 1  and D 2 . In the present embodiment, as the switching elements Q 1  and Q 2 , n-channel type IGBTs are employed. An upper arm  10 U includes the switching element Q 1  and a freewheeling diode D 1  connected in anti-parallel to the switching element Q 1 . A lower arm  10 L includes the switching element Q 2  and a freewheeling diode D 2  connected in anti-parallel to the switching element Q 2 . Note that the switching elements Q 1  and Q 2  are not limited to the IGBTs. For example, MOSFETs can be employed as the switching elements Q 1  and Q 2 . As the diodes D 1  and D 2 , parasitic diodes can be employed. 
     The upper arm  10 U and the lower arm  10 L are connected in series between a VH line  12 H and an N line  13 , such that the upper arm  10 U is positioned adjacent to the VH line  12 H. A P line  12  is an electric power line on a high potential side, and includes the VH line  12 H is connected to a positive electrode terminal of the DC power supply  2 . 
     The N line  13  is connected to a negative electrode of the DC power supply  2 , and is also referred to as a ground line. As described above, the upper and lower arm circuit  10  is provided by the upper arm  10 U and the lower arm  10 L connected in series between the electric power lines. A semiconductor device  20  described hereinbelow provides one arm. 
     A collector electrode of the switching element Q 1  is connected to the VH line  12 H. An emitter electrode of the switching element Q 2  is connected to the N line  13 . The emitter electrode of the switching element Q 1  and the collector electrode of the switching element Q 2  are connected to each other. 
     A positive electrode terminal of the capacitor C 1  is connected to the collector electrode of the switching element Q 1  of the upper arm  10 U. A negative electrode terminal of the capacitor C 1  is connected to the emitter electrode of the switching element Q 2  of the lower arm  10 L. That is, the capacitor C 1  is connected in parallel to the corresponding upper and lower arm circuit  10 . The parallel circuit  11  includes the upper and lower arm circuit  10  and the capacitor C 1  that are connected in parallel. The parallel circuit  11  has common wirings  11 P and  11 N. A connection point between the upper arm  10 U and the positive electrode terminal of the capacitor C 1  is connected to the VH line  12 H via the common wiring  11 P. A connection point between the lower arm  10 L and the negative electrode of the capacitor C 1  is connected to the N line  13  via the common wiring  11 N. 
     In the present embodiment, the capacitor C 1  is provided separately from the smoothing capacitor C 2 . The capacitor C 1  may have a function of supplying electric charges required for switching the switching elements Q 1  and Q 2  of the upper and lower arm circuit  10 , which is connected in parallel to the capacitor C 1 . Due to the switching, an energy loss occurs, and voltage between both ends of the upper arm and the lower arm drops. Therefore, the insufficient electric charges are supplied from the capacitor C 1 , which is connected in parallel. For this reason, the capacitance of the capacitor C 1  is set to a value sufficiently smaller than the capacitance of the smoothing capacitor C 2 . For example, the capacitance of the smoothing capacitor C 2  is set to 1000 μF, and the capacitance of the capacitor C 1  is set to 10 μF to 20 μF. A power module  110 , which will be described later, constitutes one parallel circuit  11 . 
     The smoothing capacitor C 2  is connected between the VH line  12 H and the N line  13 . The smoothing capacitor C 2  is connected in parallel to the inverter  7 . The smoothing capacitor C 2  smooths, for example, a DC voltage, and stores the electric charge of the DC voltage. The voltage between the ends of the smoothing capacitor C 2  provides a DC high voltage for driving the motor generator  3 . 
     The inverter  7  is connected to the DC power supply  2  via the smoothing capacitor C 2 . The inverter  7  has three sets of the parallel circuits  11  descried above. That is, the inverter  7  has the upper and lower arm circuits  10  for three phases. The connection point of the upper and lower arm circuit  10  of the V phase is connected to a U phase winding provided in a stator of the motor generator  3 . Similarly, the connection point of the upper and lower arm circuit  10  of the V phase is connected to a V phase winding of the motor generator  3 . The connection point of the upper and lower arm circuit  10  of the W phase is connected to a W phase winding of the motor generator  3 . The connection point of the upper and lower arm circuit  10  of each phase is connected to the winding of the corresponding phase via an output wiring  15  provided for each phase. 
     In the electric power conversion device  5 , the voltage of the DC power supply  2  is applied directly to the inverter  7  without being boosted. In the electric power conversion device  5 , a converter may be provided as a DC-DC conversion unit that converts the DC voltage into a DC voltage having a different value. Examples of this converter include a boost converter that is provided between the DC power supply  2  and the inverter  7 . In the power conversion device  5  provided with the boost converter, the VH line  12 H on the high potential side has, for example, 650V. 
     Further, in the electric power conversion device  5 , a filter capacitor may be connected in parallel with the DC power supply  2 . This filter capacitor is connected between the VH line  12 H and the N line, and removes power supply noise from, for example, the DC power supply  2 . In a case where the electric power conversion device  5  has both the converter and the filter capacitor, the filter capacitor is provided between the DC power supply  2  and the converter, and is arranged on the low voltage side than the smoothing capacitor C 2 . In this case, the filter capacitor may also be referred to as a low voltage side capacitor, and the smoothing capacitor may also be referred to as a high voltage side capacitor. The voltage between the ends of the smoothing capacitor C 2  is set to be equal to or higher than a voltage between the ends of the filter capacitor. At least one of the N line  13  or the VH line  12 H is provided with a system main relay (SMR) (not shown) between the DC power supply  2  and the filter capacitor. 
     The inverter  7  converts the DC voltage into a three-phase AC voltage in accordance with the switching control by the control circuit  9 , and outputs the three-phase AC voltage to the motor generator  3 . Thus, the motor generator  3  is driven to generate a predetermined torque. In response to the output of the engine, the inverter  7  can convert the three-phase AC voltage generated by the motor generator  3  into the DC voltage in accordance with the switching control by the control circuit  9 , and output the DC voltage to the VH line  12 H. In this way, the inverter  7  performs bidirectional electric power conversion between the DC power supply  2  and the motor generator  3 . 
     The control circuit  9  generates a drive instruction for operating the switching elements of the inverter  7 , and outputs the drive instruction to a drive circuit (driver), which is not shown. The control circuit  9  generates the drive instruction based on a torque request received from a higher-level ECU (not shown) or signals detected by various sensors. 
     The various sensors include a current sensor that detects a phase current flowing in the wiring of each phase of the motor generator  3 , a rotation angle sensor that detects a rotation angle of the rotor of the motor generator  3 , a voltage sensor that detects the voltage between the both ends of the smoothing capacitor C 2 , that is, the voltage of the VH line  12 H. The electric power conversion device  5  has these sensors (not shown). Specifically, the control circuit  9  outputs a PWM signal as the drive instruction. The control circuit  9  includes, for example, a microcomputer. 
     The drive circuit generates the drive signal based on the drive instruction from the control circuit  9 , and outputs the drive instruction to the gate electrodes of switching elements Q 1  and Q 2  of the corresponding upper and lower arm circuit  10 . 
     In this way, the drive circuit drives, that is, turns on and off the switching elements Q 1  and Q 2 . In the present embodiment, the drive circuit is provided for each upper and lower arm circuit  10 . 
     Next, prior to the description of the electric power conversion device  5 , the semiconductor device  20  and the power module  110  including the semiconductor device  20  will be described. The semiconductor device  20  and the power module  110  are the components of the electric power conversion device  5 . 
     (Semiconductor Device) 
     An example of the semiconductor device  20  applicable to the electric power conversion device  5  of the present embodiment will be described. The semiconductor device  20  described hereinafter is configured to provide one of upper arm or lower arm of the upper and lower arm circuit  10 , that is, one arm. In other words, the upper and lower arm circuit  10  includes two semiconductor devices  20 . The semiconductor device  20  is packaged as one element forming one arm. Thus, such a semiconductor device  20  is also referred to as 1-in-1 package. The semiconductor devices  20  have the same configuration between the upper arm  10 U and the lower arm  10 L, and thus can be provided as a common part. 
     As shown in  FIGS. 2 to 7 , the semiconductor device  20  includes a sealing resin body  30 , a semiconductor chip  40 , a conductive member  50 , a terminal member  60 , a main terminal  70 , and a signal terminal  80 .  FIG. 5  is a view in which the sealing resin body  30  is deleted from the view in  FIG. 2 .  FIG. 6  shows the semiconductor device  20  after the sealing resin body  30  is molded, but before an unnecessary portion of a lead frame  100  is removed.  FIG. 7  is a plan view showing a positional relationship between the semiconductor chip  40  and the main terminal  70 , and in which a part of the sealing resin body  30 , a conductive member  50 E, and the terminal member  60  are eliminated and not illustrated. 
     In a state where the power module  110  including the semiconductor device  20  is arranged on a cooling unit  120  described later, a plate thickness direction of the semiconductor chip  40  is substantially parallel with a Z direction that is a thickness direction of a heat exchange part  123  of the cooling unit  120 . An alignment direction of plural main terminals  70  and an alignment direction of plural signal terminals  80  are substantially parallel to the X direction, which is the alignment direction of the plural power modules  110 . Therefore, also in the following description, the plate thickness direction of the semiconductor chip  40  is indicated as the Z direction, and the alignment directions of the main terminals  70  and the signal terminals  80  are indicated as the X direction. 
     The sealing resin body  30  is made of, for example, an epoxy resin. The sealing resin body  30  is formed by, for example, a transfer molding method. As shown in  FIGS. 2 to 4 , the sealing resin body  30  has one surface  31  and a rear surface  32  opposite to the one surface  31  in the Z direction, which is parallel to the plate thickness direction of the semiconductor chip  40 . The one surface  31  and the rear surface  32  are, for example, flat surfaces. The sealing resin body  30  has a lateral surface connecting the one surface  31  and the rear surface  32 . In the present example, the sealing resin body  30  has substantially a rectangular shape in a plan view. 
     The semiconductor chip  40  is provided by a semiconductor substrate, such as Si, SiC, or GaN substrate, on which elements are formed. The semiconductor device  20  has one semiconductor chip  40 . The semiconductor chip  40  is formed with elements (switching element and diode) constituting one arm as described above. That is, an RC (reverse conducting)-IGBT is formed as the elements. For example, when the semiconductor chip  40  is used for the upper arm  10 U, the element formed in the semiconductor chip  40  functions as the switching element Q 1  and the diode D 1 . On the other hand, when the semiconductor chip  40  is used for the lower arm  10 L, the element formed in the semiconductor chip  40  functions as the switching element Q 2  and the diode D 2 . 
     The element has a vertical structure so that the main current flows in the Z direction. Although not illustrated, the element has a gate electrode. The gate electrode has a trench structure. As shown in  FIG. 3 , the semiconductor chip  40  has main electrodes on opposite surfaces in the Z direction. Specifically, the semiconductor chip  40  has, as the main electrodes, a collector electrode  41  on one surface and an emitter electrode  42  on a rear surface opposite to the one surface. The collector electrode  41  also serves as a cathode electrode of the diode, and the emitter electrode  42  also serves as an anode electrode of the diode. The collector electrode  41  is formed in an almost entire region on the one surface. The emitter electrode  42  is formed at a part of the rear surface. 
     As shown in  FIG. 3  and  FIG. 7 , the semiconductor chip  40  has pads  43  for signal electrodes on the rear surface on which the emitter electrode  42  is formed. The pads  43  are formed in a region different from the emitter electrode  42 . The pads  43  are electrically separated from the emitter electrode  42 . The pads  43  are formed at an end on the side opposite to the formation region of the emitter electrode  42  in the Y direction. 
     In the present example, the semiconductor chip  40  has five pads  43 . Specifically, the five pads  43  are provided for a gate electrode, a Kelvin emitter for detecting a potential of the emitter electrode  42 , a current sense, an anode potential of a temperature sensor (temperature-sensitive diode) for detecting a temperature of the semiconductor chip  40 , and a cathode potential. The five pads  43  are collectively formed in an area adjacent to one end in the Y direction in the semiconductor chip  40  having a substantially rectangular planar shape, and are aligned side by side in the X direction. 
     The conductive member  50  electrically connects the semiconductor chip  40  and the main terminal  70 . That is, the conductive member  50  functions as a wiring for the main electrode. In the present example, the conductive member  50  also functions to dissipate heat of the semiconductor chip  40  (element) to the outside of the semiconductor device  20 . Therefore, the conductive member  50  is also referred to as a heat sink. The conductive member  50  is formed of at least a metal material such as Cu for securing an electrical conductivity and a thermal conductivity. 
     The conductive members  50  are arranged in a pair so as to interpose the semiconductor chip  40  therebetween. Each of the conductive members  50  is arranged so as to encompass the semiconductor chip  40  in a projection view in the Z direction. The semiconductor device  20  has, as the pair of the conductive members  50 , a conductive member  50 C arranged adjacent to the collector electrode  41  of the semiconductor chip  40  and a conductive member  50 E arranged adjacent to the emitter electrode  42 . The conductive member  50 C electrically connects the collector electrode  41  and a main terminal  70 C described later. The conductive member  50 E electrically connects the emitter electrode  42  and a main terminal  70 E described later. 
     As shown in  FIG. 3 ,  FIG. 5 , and  FIG. 7 , the conductive member  50 C has a main portion  51 C that is a thick portion in the Z direction and an extension portion  52 C that is a portion thinner than the main portion  51 C. The main portion  51 C has a substantially planar shape with a substantially constant thickness. The main portion  51 C has a mounting surface  53 C adjacent to the semiconductor chip  40  in the Z direction and a heat radiation surface  54 C opposite to the mounting surface  53 C in the Z direction. The extension portion  52 C extends from the end of the main portion  51 C in the Y direction. The extension portion  52 C extends in the Y direction with the same length in the X direction, that is, the same width as the main portion  51 C. A surface of the extension portion  52 C adjacent to the semiconductor chip  40  is substantially flush with the mounting surface  53 C of the main portion  51 C. An opposite surface of the extension portion  52 C further from the semiconductor chip  40  is sealed by the sealing resin body  30 . The extension portion  52 C may be provided at, at least, an end of the conductive member  50 C, at which the main terminals  70  are provided. In the present example, the conductive member  50 C has the extension portions  52 C at both ends of the main portion  51 C. In  FIG. 7 , a boundary between the main portion  51 C and the extension portion  52 C is shown by a long dashed double-dotted line. 
     As shown in  FIG. 3  and  FIG. 5 , the conductive member  50 E has a main portion  51 E that is a thick portion in the Z direction and an extension portion  52 E that is a portion thinner than the main portion  51 E. The main portion  51 E has the substantially planar shape having the substantially constant thickness. The main portion  51 E has a mounting surface  53 E adjacent to the semiconductor chip  40  in the Z direction and a heat radiation surface  54 E opposite to the mounting surface  53 C in the Z direction. The extension portion  52 E extends from the end of the main portion  51 E in the Y direction. The extension portion  52 E extends in the Y direction with the same length in the X direction, that is, the same width as the main portion  51 E. A surface of the extension portion  52 E adjacent to the semiconductor chip  40  is substantially flush with the mounting surface  53 E of the main portion  51 E. An opposite surface of the extension portion  52 E farther from the semiconductor chip  40  is sealed by the sealing resin body  30 . The extension portion  52 E may be provided at, at least, an end of the conductive member  50 E, at which the main terminals  70  are provided. In the present example, the conductive member  50 E has the extension portions  52 E at both ends of the main portion  51 E. In the present example, the conductive members  50 C and  50 E are provided by common parts. 
     The mounting surface  53 C of the main portion  51 C of the conductive member  50 C is connected to the collector electrode  41  of the semiconductor chip  40  via a solder  90 . The connection method is not limited to solder joining. Most part of the conductive member  50 C is covered with the sealing resin body  30 . The heat radiation surface  54 C of the conductive member  50 C is exposed from the sealing resin body  30 . The heat radiation surface  54 C is substantially flush with the one surface  31 . Of the surfaces of the conductive member  50 C, areas other than a connection portion with the solder  90 , the heat radiation surface  54 C, and portions to which the main terminals  70  are connected are covered with the sealing resin body  30 . 
     The terminal member  60  is located between the semiconductor chip  40  and the conductive member  50 E. The terminal member  60  has a substantially rectangular parallelepiped shape. The terminal member  60  has the planar shape (substantially rectangular shape) that substantially coincides with the emitter electrode  42 . Since the terminal member  60  is positioned in the middle of an electric conduction and thermal conduction path between the emitter electrode  42  of the semiconductor chip  40  and the conductive member  50 E, the terminal member  60  is formed of at least a metal material such as Cu for securing the electric conductivity and the thermal conductivity. The terminal member  60  is arranged to face the emitter electrode  42  and is connected to the emitter electrode  42  via a solder  91 . The connection method is not particularly limited to solder joining. The terminal member  60  may be provided as a part of the lead frame  100  as described later. 
     The mounting surface  53 E of the main portion  51 E of the conductive member  50 E is electrically connected to the emitter electrode  42  of the semiconductor chip  40  via a solder  92 . Specifically, the conductive member  50 E and the terminal member  60  are connected via the solder  92 . The emitter electrode  42  and the conductive member  50 E are electrically connected via the solder  91 , the terminal member  60 , and the solder  92 . Most part of the conductive member  50 E is covered with the sealing resin body  30 . The heat radiation surface  54 E of the conductive member  50 E is exposed from the sealing resin body  30 . The heat radiation surface  54 E is substantially flush with the rear surface  32 . Of the surfaces of the conductive member  50 E, areas other than a connection portion with the solder  92 , the heat radiation surface  54 E, portions to which the main terminals  70  are connected are covered with the sealing resin body  30 . 
     The main terminals  70  are terminals through which the main current flows, among external connection terminals for electrically connecting the semiconductor device  20  and an external device. The semiconductor device  20  includes the multiple main terminals  70 . The main terminals  70  connect to the corresponding conductive member  50 . The main terminals  70  may be formed integrally with the corresponding conductive member  50  by processing one metal member. 
     Alternatively, the main terminals  70  may be formed as separate members and be integrated to connect to the conductive member  50 . In the present example, as shown in  FIG. 6 , the main terminals  70  are formed as parts of the lead frame  100  together with the signal terminals  80 , and are provided as members different from the conductive member  50 . As shown in  FIG. 3 , the main terminals  70  are connected to the corresponding conductive member  50  in the sealing resin body  30 . 
     As shown in  FIG. 3  and  FIG. 4 , each of the main terminals  70  extends from the corresponding conductive member  50  in the Y direction, and projects from one lateral surface  33  of the sealing resin body  30  to the outside. The main terminal  70  extends from the inside of the sealing resin body  30  to the outside. The main terminal  70  is a terminal electrically connected to the main electrode of the semiconductor chip  40 . The semiconductor device  20  includes, as the main terminals  70 , a main terminal  70 C electrically connected to the collector electrode  41  and a main terminal  70 E electrically connected to the emitter electrode  42 . The main terminal  70 C is also referred to as the collector terminal, and the main terminal  70 E is also referred to as the emitter terminal. 
     The main terminal  70 C connects to the conductive member  50 C. Specifically, the main terminal  70 C is connected to a surface of one of the extension portions  52 C via a solder  93 , the surface being adjacent to the semiconductor chip  40 . The connection method is not particularly limited to solder joining. The main terminal  70 C extends in the Y direction from the conductive member  50 C and projects outside of the sealing resin body  30  from the lateral surface  33 . The main terminal  70 E connects to the conductive member  50 E. Specifically, the main terminal  70 E is connected to a surface of one of the extension portions  52 E via a solder  94 , the surface being adjacent to the semiconductor chip  40 . The connection method is not particularly limited to solder joining. The main terminal  70 E extends from the conductive member  50 E in the Y direction that is the same direction as the main terminal  70 C, and projects outside of the sealing resin body  30  from the same lateral surface  33  as the main terminal  70 C, as shown in  FIG. 3  and  FIG. 4 . Details of the main terminals  70 C and  70 E will be described later. 
     The signal terminals  80  are connected to the respective pads  43  of the semiconductor chip  40 . The semiconductor device  20  includes the multiple signal terminals  80 . In the present example, the multiple signal terminals  80  are connected via bonding wires  95 . The signal terminals  80  are connected to the bonding wires  95  inside the sealing resin body  30 . Five signal terminals  80  connected to the respective pads  43  extend in the Y direction, and project outside of the sealing resin body  30  from a lateral surface  34  opposite to the lateral surface  33 . The signal terminals  80  are made as parts of the lead frame  100 . The signal terminals  80  may be integrally formed with the conductive member  50 C, together with the main terminals  70 C, by processing the same metal member. 
     The lead frame  100  includes an outer peripheral frame portion  101  and tie bars  102  in a state before being cut, as shown in  FIG. 6 . Each of the main terminals  70  and each of the signal terminals  80  are fixed to the outer peripheral frame portion  101  through tie bars  102 . After the sealing resin body  30  is molded, unnecessary portions of the lead frame  100  such as the outer peripheral frame portion  101  and the tie bars  102  are removed. As a result, the main terminals  70  and the signal terminals  80  are electrically separated, and the semiconductor device  20  is obtained. As the lead frame  100 , either a material having a constant thickness or a deformed material having non-constant thickness can be used 
     In the semiconductor device  20  configured as described above, the sealing resin body  30  integrally seals the semiconductor chip  40 , a part of each of the conductive members  50 , the terminal member  60 , a part of each of the main terminals  70 , and a part of each of the signal terminals  80 . That is, the sealing resin body  30  seals the elements constituting one arm. Therefore, the semiconductor device  20  is also referred to as 1-in-1 package. 
     The heat radiation surface  54 C of the conductive member  50 C is substantially flush with the one surface  31  of the sealing resin body  30 . The heat radiation surface  54 E of the conductive member  50 E is substantially flush with the rear surface  32  of the sealing resin body  30 . The semiconductor device  20  has a double-sided heat radiation structure in which the heat radiation surfaces  54 C and  54 E are both exposed from the sealing resin body  30 . The semiconductor device  20  having such a structure can be formed, for example, by cutting the conductive members  50  together with the sealing resin body  30 . Alternatively, the semiconductor device  20  can be formed by molding the sealing resin body  30  in a state where the heat radiation surfaces  54 C and  54 E contact with a cavity wall surface of a mold for molding the sealing resin body  30 . 
     Next, the main terminals  70  will be described in detail. 
     The main terminals  70  include plural terminals as at least one of the main terminals  70 C and the main terminals  70 E. The main terminals  70 C and the main terminals  70 E are aligned such that plate surfaces of the main terminals  70 C and plate surfaces of the main terminals  70 E do not face each other, but lateral surfaces of the main terminals  70 C and lateral surfaces of the main terminals  70 E face each other in the X direction, which corresponds to the plate width direction of the main terminals  70 . The semiconductor device  20  includes multiple lateral surface facing portions formed by the adjacent main terminals  70 C and  70 E. The plate surface is a surface facing in the plate thickness direction of the main terminal  70  among the surfaces of the main terminal  70 . The lateral surface is a surface that connects between the plate surfaces and is along the extension direction of the main terminal  70 . The remaining surfaces of the main terminal  70  include opposite end surfaces in the extension direction, that is, a projection tip surface and an opposite back end surface. The lateral surfaces of the main terminals  70 , which form the lateral surface facing portion, face each other at least at a part in the plate thickness direction of the main terminals  70 . For example, the main terminals  70  may be arranged to be offset in the plate thickness direction. However, it is effective when the lateral surfaces of the main terminals  70  face each other in an entire area. As the meaning of the facing, it is sufficient that, at least, facing surfaces face each other. It is preferable that surfaces are substantially parallel to each other, and is more preferable that surfaces are completely parallel to each other. 
     The lateral surface of the main terminal  70  is a surface that has a smaller area than that of the plate surface. The main terminals  70 C and the  70 E are arranged next to each other. In a configuration in which the main terminals  70  includes the multiple main terminals  70 C and the multiple main terminals  70 E, when the main terminals  70 C and the main terminals  70 E are arranged next to each other, the main terminals  70 C and the main terminal  70 E are located alternately. The main terminals  70 C and the main terminals  70 E are arranged in order. 
     As shown in  FIG. 7 , three or more main terminals  70  that are arranged continuously next to each other in the X direction are included in a main terminal group  71 . As described above, the main terminals  70 C and the main terminals  70 E are arranged adjacent to each other. Thus, the main terminal group  71  includes both of the main terminal  70 C and the main terminal  70 E, as well as includes plural number of at least one of the main terminals  70 C and the main terminal  70 E. The main terminals  70  included in the main terminal group  71  are arranged such that at least a part of each main terminal  70  is located in a predetermined area A 1 . The area A 1  is defined between an extension line EL 1  virtually extending from an end surface  44  of the semiconductor chip  40  and an extension line EL 2  virtually extending from an end surface  45  of the semiconductor chip  40  opposite to the end surface  44 . The distance between the extension line EL 1  and the extension line EL 2  in the X direction corresponds to the width of the semiconductor chip  40  in the X direction, that is, an element width. 
     In the present example, the main terminals  70 C and  70 E extend in the same direction (Y direction) over their entire length. The main terminal  70  has a straight plane shape, and does not have an extended portion in the X direction. The thickness of the main terminal  70 C is thinner than that of the main portion  51 C, and is, for example, almost the same as that of the extension portion  52 C. The thickness of the main terminal  70 E is thinner than that of the main portion  51 E, and is, for example, almost the same as that of the extension portion  52 E. The thickness of the main terminal  70  is substantially constant in its entire length, and the main terminal  70 C and the main terminals  70 E have substantially the same thickness. A width W 1  of the main terminal  70  is substantially constant in its entire length, and the main terminal  70 C and the main terminal  70 E have the same width. An interval P 1  between the adjacent main terminals  70  in the X direction is also the same for all the main terminals  70 . The interval P 1  is also referred to as an inter-terminal pitch. 
     Each of the main terminals  70  has two bent portions inside of the sealing resin body  30 . Thus, the main terminal  70  has a substantially crank shape in a ZY plane. In the main terminal  70 , a portion close to the tip end than the bent portion has a flat plate shape, and a part of the flat plate shaped portion projects from the sealing resin body  30 . The projected portions of the main terminals  70 C and  70 E projecting from the sealing resin body  30 , that is, the flat plate shaped portions of the main terminals  70 C and  70 E are located at substantially the same position in the Z direction, as shown in  FIG. 3  and  FIG. 4 . Further, in the flat plate shaped portions, the plate thickness directions of the main terminals  70 C and  70 E are substantially coincide with the Z direction. As a result, the lateral surfaces of the main terminals  70 C and the lateral surfaces of the main terminals  70 E face each other in substantially entire areas in the Z direction. Further, the extension lengths of the flat shaped portions of the main terminals  70 C and  70 E are substantially the same. The main terminals  70 C and the main terminal  70 E are located at substantially the same positions in the Y direction. As a result, the lateral surfaces of the main terminal  70 C and the lateral surfaces of the main terminals  70 E face each other in substantially entire areas in the flat plate shaped portions. 
     As shown in  FIG. 2 , and  FIGS. 5 to 7 , the semiconductor device  20  includes an odd number of main terminals  70 , specifically, nine main terminals  70 . The nine main terminals  70  include four main terminals  70 C and five main terminals  70 E. The main terminals  70 C and  70 E are alternately arranged in the X direction. Thus, the semiconductor device  20  has eight lateral surface facing portions. The main terminals  70 E are located at opposite ends of the nine main terminals  70  in the X direction, and seven main terminals  70  excluding the main terminals  70 E at the opposite ends are included in the main terminal group  71 . The main terminal group  71  is composed of an odd number (seven) of the main terminals  70 , specifically, four main terminals  70 C and three main terminals  70 E. The entire part of each of the two main terminals  70 E that are not included in the main terminal group  71  is located outside of the area A in the X direction. The number of main terminals  70  that are included in the main terminal group  71  is larger than the number of main terminals  70  that are not included in the main terminal group  71 . 
     Of the seven main terminals  70  included in the main terminal group  71 , a part of each of the two main terminals  70 C at both ends is located in the area A 1  in the X direction. The remaining five main terminals  70  are located entirely in the area A 1  in the X direction. As described above, some of the main terminals  70  included in the main terminal group  71  are entirely located in the area A 1 , and the remaining main terminals  70  are partially located in the area A 1 . In particular, in the present example, each of the multiple (five) main terminals  70  included in the main terminal group  71  is entirely placed in the area A 1 . 
     As described above, the main terminals  70 C and  70 E have the same width W 1 , and the interval P 1  between the main terminals  70 C and  70 E is also the same for all the main terminals  70 . A center of the width of the main terminal  70 E placed at the center in the X direction among the odd number of main terminals  70  is located on a center line CL passing through the center of the semiconductor chip  40 . In this way, the main terminals  70 C and  70 E are arranged symmetrically with respect to the center line CL passing through the center of the semiconductor chip  40  in the X direction. The multiple main terminals  70 C are arranged symmetrically with respect to the center line CL, and the main terminal  70 E are arranged symmetrically with respect to the center line CL. The odd number of main terminals  70  included in the main terminal group  71  are arranged symmetrically with respect to the center line CL. The extension direction of the center line CL is orthogonal to the Z direction and the X direction. 
     Next, the effects of the semiconductor device  20  described above will be described. 
     In the semiconductor device  20 , at least one of the number of main terminals  70 C or the number of main terminals  70 E is multiple, and the main terminals  70 C and  70 E are arranged adjacent to each other in the X direction. The lateral surfaces of the adjacent main terminals  70 C and  70 E face each other. The flow direction of the main current in the main terminal  70 C is opposite to that in the main terminal  70 E. In this way, the main terminals  70 C and  70 E are arranged so as to cancel out the magnetic fluxes to each other, which are generated when the main currents flow. Therefore, it is possible to reduce the inductance. In particular, in the present example, since the multiple lateral surface facing portions of the main terminals  70 C and  70 E are provided, the inductance can be effectively reduced. Since the multiple main terminals  70  having the same type are arranged in parallel, the inductance can be reduced. 
     The main terminal group  71  is provided by at least three main terminals  70  continuously arranged. At least a part of each main terminal  70  included in the main terminal group  71  is located in the area A 1  defined, in the X direction, between the extension lines EL 1  and EL 2  extending from the opposite end surfaces  44  and  45  of the semiconductor chip  40 . That is, the multiple lateral surface facing portions are located in the area A 1 . As a result, it is possible to simplify the current path between the main terminal  70  included in the main terminal group  71  and the main electrode of the semiconductor chip  40 , specifically, shorten the current path. As such, the inductance can be reduced. 
     As described above, according to the semiconductor device  20  described hereinabove, it is possible to reduce the inductance of the main circuit wiring, as compared with a conventional structure. In the configuration in which the multiple main terminals  70  are arranged in the X direction so that the lateral surfaces face each other and at least one of the main terminal  70 C and the main terminal  70 E includes a plural number of main terminals, the main terminal group  71  may be provided by at least three main terminals  70  and the same type of main terminals  70  may be arranged continuously at least at a part. In such a configuration, at least one of the main terminal  70 C and the main terminal  70 E is provided with plural number, and arranged in parallel. Therefore, it is possible to reduce the inductance. Since the main terminal group  71  is provided, it is possible to simplify the current path between the main terminal  70  included in the main terminal group  71  and the main electrode of the semiconductor chip  40 . As such, it is possible to reduce the inductance. Accordingly, the effects in accordance with the present example can be achieved. However, as shown in the present example, when the main terminals  70 C and  70 E are arranged adjacent to each other, it is possible to further reduce the inductance due to the effect of canceling out the magnetic fluxes. 
     In the main terminal group  71 , the main terminal  70  entirely located in the area A 1  in the X direction is more preferable in respect of the simplification of the current path as compared with the main terminal  70  partially located in the area A 1 . In the present example, some of the main terminals  70  included in the main terminal group  71  are entirely located in the area A 1 , and the remaining main terminals  70  are partially located in the area A 1 . Since the main terminal group  71  includes the main terminals  70  that are more effective for simplifying the current path, it is possible to effectively reduce the inductance. In particular, in the present example, the main terminal group  71  includes the multiple number of the main terminals  70  entirely located in the area. Since the main terminal group  71  includes the multiple main terminals  70  that are more effective for simplifying the current path, it is possible to further effectively reduce the inductance. 
     In the present example, the number of the main terminals  70  is an odd number. In the case where the number of the main terminals  70  is an odd number, it is easy to arrange symmetrically in the X direction, and thus it is possible to suppress the bias of the current paths between the main terminals  70  and the semiconductor chip  40 . Further, the arrangement order of the main terminals  70  in the X direction is the same when viewed from the one surface  31  and when viewed from the rear surface  32 . Accordingly, it is possible to improve freedom of arrangement of the semiconductor device  20 . 
     In particular, in the present example, the main terminals  70 C and  70 E are arranged symmetrically with respect to the center line CL of the semiconductor chip  40  in the X direction. Thus, the main current of the semiconductor chip  40  flows symmetrically with respect to the center line CL. The main current flows almost evenly on the left side and the right side with respect to the center line CL. Accordingly, it is possible to further reduce the inductance. In addition, it is possible to suppress local heat generation. 
       FIGS. 8 to 10  show other examples. In  FIGS. 8 to 10 , for the sake of convenience, the sealing resin body  30  and the signal terminal  80  are not illustrated. In  FIGS. 8 to 10 , for the sake of convenience, the area A 1  is not illustrated, rather the extension lines EL 1  and EL 2  defining the area A 1  are illustrated. 
     In an example shown in  FIG. 8 , the semiconductor device  20  includes three main terminals  70 , specifically, one main terminal  70 C and two main terminals  70 E. That is, the semiconductor device  20  includes two lateral surface facing portions. All the main terminals  70  are included in the main terminal group  71 . The main terminal  70 C located at the center is entirely arranged, in the X direction, in the area A 1 . The main terminals  70 E at the both ends are partially located in the area A 1 . 
     In an example shown in  FIG. 9 , the semiconductor device  20  includes five main terminals  70 , specifically, two main terminals  70 C and three main terminals  70 E. That is, the semiconductor device includes four lateral surface facing portions. All the main terminals  70  are included in the main terminal group  71 . Each of the main terminals  70 E at both ends is partially located in the area A 1 . Each of the remaining three main terminals  70  is entirely located in the area A 1 . 
     In an example shown in  FIG. 10 , the semiconductor device  20  includes seven main terminals  70 , specifically, three main terminals  70 C and four main terminals  70 E. That is, the semiconductor device  20  includes six lateral surface facing portions. All the main terminals  70  are included in the main terminal group  71 . Each of the main terminals  70 E at both ends is partially located in the area A 1 . Each of the remaining five main terminals  70  is entirely located in the area A 1 . 
       FIG. 11  shows a result of a magnetic field analysis of a total inductance of the main terminals of the semiconductor device  20 . In this magnetic field analysis (simulation), a length (width) of the conductive member  50  in the X direction is set to 17 millimeters (mm), and the interval P 1  of the main terminals  70  is set to 1.0 mm. In the main terminals  70  of the same semiconductor device  20 , the widths W 1  are set to be equal to each other. For example, the result of the configuration in which the semiconductor device  20  has three main terminals  70  is indicated as “three terminals” in  FIG. 11 . In  FIG. 11 , the result of a configuration including only two main terminals is shown as a comparative example (two terminals). “Nine terminal” is the result of the same configuration as shown in  FIG. 7 . Similarly, “three terminals”, “five terminals”, and “seven terminals” are, respectively, results of the same configurations as shown in  FIG. 8 ,  FIG. 9  and  FIG. 10 . 
     As the number of terminals increases, the width of each terminal becomes narrower and the inductance (self-inductance) increases. However, the number of the lateral surface facing portions increases. With this, the number of the main terminals  70  included in the main terminal group  71  increases up to a predetermined number with the increase in the number of the main terminals  70 . Therefore, the inductance can be reduced. In the configurations of the three terminal, the five terminals and the seven terminals, as shown in  FIGS. 8 to 10 , all the main terminals  70  are included in the main terminal group  71 . That is, all the main terminals  70  are located in the area A 1 . In the configuration of the nine terminals, as shown in  FIG. 7 , seven main terminals  70  are included in the main terminal group  71 . 
     According to the results shown in  FIG. 11 , when the main terminal group  71  includes there or more main terminals  70 , it is clear that the total inductance of the main terminals can be reduced while suppressing the increase in size, as compared with the comparative example. It is considered that, when the number of terminals is three or more, the effect of reducing the inductance exceeds the increase in inductance due to the decrease in the width, and thus the inductance is reduced. In particular, in the configuration where the main terminal group  71  includes five or more main terminals  70 , the inductance can be reduced by half or less as compared with the comparative example. That is, it is clear to effectively reduce the inductance. 
     In the configuration of the nine terminals, the seven main terminals  70  are included in the main terminal group  71  and the two main terminals  70  are located outside the area A 1 . Although the two main terminals  70  are located outside the area A 1  as described above, the number of the main terminals  70  located in the area A 1  is larger than that of the main terminals  70  not included in the main terminal group  71 , that is, most of the main terminals  70  are located in the area A 1 . In addition, the number of lateral surface facing portions is larger by two, as compared with the configuration of the seven terminals. Accordingly, the inductance is lower than that of the configuration of the seven terminals. 
     In the example described above, the configuration in which the main terminals  70 E are located at both ends, that is, the configuration in which the number of main terminals  70 E is larger than the number of main terminals  70 C has been exemplified. However, the present embodiment is not limited to such an example. In the configuration of the odd number of main terminals  70 , the number of main terminals  70 C may be larger than the number of main terminals  70 E. 
     The example in which the projection lengths of all the main terminals  70  projecting from the sealing resin body  30  are the same has been described. However, the present embodiment is not limited to such an example. In consideration of connectivity with bus bars or the like, the projected portions of the adjacent main terminals  70 C and  70 E may have different length from each other. In another example shown in  FIG. 12 , the main terminals  70 C are longer than the main terminals  70 E. 
     In another example shown in  FIG. 13 , the number of main terminals  70 C is smaller than the number of main terminals  70 E. Further, a cross-sectional area of the main terminal  70 C is larger than a cross-sectional area of the main terminal  70 E, so that the total impedance of the main terminals  70 C and the total impedance of the main terminals  70 E are made to be substantially the same. Accordingly, it is possible to suppress the heat generation of a smaller number of main terminals  70 C. In the example shown in  FIG. 13 , the cross-sectional area of the main terminal  70 C is made larger than the cross-sectional area of the main terminal  70 E by increasing the width. However, the cross-sectional area of the main terminal  70 C may be made larger than the cross-sectional area of the main terminal  70 E by increasing the thickness of the main terminal  70 C larger than that of the main terminal  70 E. Alternatively, both of the width and the thickness may be adjusted. In the example shown in  FIG. 13 , the length of the smaller number of the main terminals  70 C in the extension direction is longer than the length of the larger number of the main terminals  70 E. The longer main terminal has the larger cross-sectional area. Therefore, it is possible to ensure the rigidity of the main terminals  70 .  FIG. 12  and  FIG. 13  show the examples of the seven terminals. However, the configurations are not limited to such examples. 
     The example in which the adjacent main terminals  70 C and  70 E face each other entirely in the extension direction in the projected portions projecting from the sealing resin body  30  has been described. However, the present embodiment is not limited to such an example. Alternatively, the lateral surfaces may not face each other at least at a part of the projected portions. For example, the projection tip end portion of at least one of the main terminal  70 C or the main terminal  70 E is bent, and thereby the lateral surface may not face at the projection tip end portion. Even when the extension lengths are the same, the connectivity with the bus bar or the like can be improved. However, the effect of reducing the inductance is reduced. 
     In the example in which the number of main terminals  70  is odd and the number of main terminals  70  configuring the main terminal group  71  is odd has been shown. However, the present embodiment is not limited to such an example. The main terminal group  71  may include an even number of (four or more) main terminals  70 . 
     The semiconductor device  20  includes at least one semiconductor chip  40 . For example, in a configuration in which the semiconductor device  20  includes the multiple semiconductor chips  40  and these semiconductor chips  40  are connected in parallel between the main terminals  70 C and  70 E, the above described arrangement of the main terminals  70  may be employed to each of the semiconductor chips  40 . 
     All the main terminals  70  included in the main terminal group  71  may be entirely arranged in the area A 1 . In another example shown in  FIG. 14 , the main terminal group  71  includes five main terminals  70 , among the seven main terminals  70 . The five main terminals  70  included in the main terminal group  71  are entirely arranged in the area A 1 . In such a configuration, it is possible to more simplify the current path with the main electrode of the semiconductor chip  40 . 
     The semiconductor device  20  may have an even number of (four or more) of main terminals  70 . In another example shown in  FIG. 15 , the semiconductor device  20  includes two main terminals  70 C and two main terminals  70 E. The main terminals  70 C and the main terminals  70 E are alternately arranged. The four main terminals  70  have the equal width W 1  and the equal thickness to each other. That is, the cross sectional areas of the four main terminals  70  orthogonal to the extension direction are equal to each other. Further, the four main terminals  70  have the equal length to each other in the Y direction. All the main terminals  70  are included in the main terminal group  71 . The two main terminals  70 C and  70 E, which are at opposite ends, are partially located in the area A 1  in the X direction. The two main terminals  70 C and  70 E, which are in the middle, are entirely located in the area A 1 . 
     Even in such a configuration, the min terminals  70 C and  70 E form multiple lateral surface facing portions, and thus it is possible to effectively reduce the inductance. Since the semiconductor device  20  has the main terminal group  71 , it is possible to simplify the current path between the main terminals  70  of the main terminal group  71  and the main electrode of the semiconductor chip  40 , thereby to reduce the inductance. As described above, it is possible to reduce the inductance of the main circuit wiring as compared with the conventional structure.  FIG. 11  also shows the result of the configuration of the four terminals. From the results of  FIG. 11 , even when the number of terminals is four, it is clear that the total inductance of the main terminals can be reduced while suppressing the increase in the size, as compared with the comparative example. 
     In  FIG. 15 , since the main terminal group  71  is provided by all the main terminals  70 , the inductance can be effectively suppressed. Even when the number of main terminals  70  is an even number, it is sufficient that the main terminal group  71  is provided by three or more main terminals  70  arranged continuously. Accordingly, in the configuration including the four main terminals  70 , the three main terminals  70  may be included in the main terminal group  71  and the remaining one main terminal  70  may be arranged outside the area A 1 . As described above, in the case where the number of main terminal  70  is the even number, the main terminal group  71  may be made of the odd number of (three or more) main terminals  70 . 
     In the case where the number of main terminals  70  is the even number, the number of main terminals  70 C and the number of main terminals  70 E are the same. Therefore, the main current flowing in the main terminal  70 C and the main current flowing in the main terminal  70 E are equal. As such, variations in heat generation can be suppressed. In the example shown in  FIG. 15 , the extension lengths of the main terminals  70 C and  70 E are equal to each other, and the cross-sectional areas of the main terminals  70 C and  70 E are equal to each other. As such, the impedances of the main terminals  70 C and  70 E are substantially equal to each other. Accordingly, the variation in heat generation can be effectively suppressed. 
     The even number is not limited to four. The even number may be four or more. For example, a configuration including six main terminals  70  or a configuration including eight main terminals  70  may be applicable. Similarly to the configuration of the odd number, the length of the projected portions may be different between the adjacent main terminals  70 C and  70 E. Further, of the main terminals  70 C and  70 E, the cross-sectional area of the one having the longer projected portion may be larger than the cross-sectional area of the other having the shorter projected portion. As a result, rigidity can be ensured. Further, the impedance can be made equal between the main terminal  70 C and the main terminal  70 E. The lateral surfaces may not face each other at a part of the projected portions. 
     It may be possible to further have a connecting portion, as a part of the lead frame, integrally provided with at least one of the main terminals  70 C and the main terminals  70 E to connect the at least same one of the main terminals  70 C and the main terminals  70 E to each other through the connecting portion. In another example shown in  FIG. 16 , the semiconductor device  20  includes five main terminals  70 , specifically, two main terminals  70 C and three main terminals  70 E. The lead frame  100  described above has a connecting portion  96  connecting between the main terminals  70 E. The main terminals  70 E have the longer projection length than the main terminals  70 C from the sealing resin body  30 , and the connecting portion  96  connects the projection tip end portions of the main terminals  70 E. The connecting portion  96  is extended in the X direction, and is spaced apart from the main terminals  70 C in the Y direction. The connecting portion  96  is located at the same position as the projecting portions of the main terminals  70 C and  70 E in the Z direction. 
     Thus, when the main terminals  70  having the same potential (the main terminals  70 E) are connected through the connecting portion  96 , connection points with bus bars or the like can be reduced. That is, the connectivity can be improved. In particular, in  FIG. 16 , the main terminals  70 E having the larger number are connected to each other. Thus, in the configuration where the main terminals  70 C and  70 E and the connecting portion  96  are provided in the same lead frame  100 , the number of connection points can be further reduced. In place of the main terminals  70 E, the main terminals  70 C may be connected through the connecting portion  96 . Of the main terminals  70 C and the main terminals  70 E, the one having smaller number may be connected through the connecting portion  96 . The number and the arrangement of the main terminals  70  are not limited to the example shown in  FIG. 16 . In a case where the connecting portion  96  is provided to only either the main terminals  70 C or the main terminals  70 E, the connecting portion  96  can be arranged on the same plane as the projecting portions of the main terminals  70 C and  70 E as described above. Such a configuration may be combined with the configuration of having the even number of the main terminals  70 . 
     Each of the main terminals  70 C and  70 E may be connected through the connecting portion. In another example shown in  FIG. 17  and  FIG. 18 , the conductive members  50 C and  50 E have the main portions  51 C and  51 E, but may not have the extension portions  52 C and  52 E, respectively. Further, the conductive member  50 C, the main terminals  70 C and the signal terminals  80  are formed in the same lead frame. The conductive member  50 E and the main terminals  70 E are formed in a lead frame, which is different from the lead frame in which the main terminals  70 C are formed. The main terminals  70 C extend from the conductive member  50 C and the main terminals  70 E extend from the conductive member  50 E.  FIG. 18  is a cross-sectional view of the semiconductor device  20  taken along the line XVIII-XVIII in  FIG. 17 . 
     In  FIG. 17  and  FIG. 18 , the lead frame including the main terminals  70 C is provided with the connecting portion  96 C, and the lead frame including the main terminals  70 E is provided with the connecting portion  96 E. The connecting portion  96 C connects the projection tip end portions of the projected portions of the main terminals  70 C. Likewise, the connecting portion  96 E connects the projection tip end portions of the projected portions of the main terminals  70 E. The main terminals  70 C and  70 E each have a bent portion in the projected portion, and hence the connecting portions  96 C and  96 E are separated from each other in the Z direction. That is, the connecting portions  96 C and  96 E are arranged at different positions from each other in the Z direction. As such, even if the main terminals  70 C and  70 E have the same extension length, the main terminals  70 C and the main terminals  70 E can be connected respectively through the connecting portions  96 C and  96 E. Thus, the number of the connection points can be further reduced. 
     In another example shown in  FIG. 19  and  FIG. 20 , the semiconductor device  20  includes multiple semiconductor chips  40  connected in parallel to each other. Specifically, the semiconductor device  20  includes, as the semiconductor chips  40 , a semiconductor chip  40   a  and a semiconductor chip  40   b . Note that  FIG. 19  is a cross-sectional view of the semiconductor device  20  taken along a line XIX-XIX in  FIG. 20 . Collector electrodes  41  of the semiconductor chips  40   a  and  40   b  are connected to a mounting surface  53 C of the same conductive member  50 C. Emitter electrodes  42  of the semiconductor chips  40   a  and  40   b  are connected to a mounting surface  53 E of the same conductive member  50 E through terminal members  60 , which are individually arranged. In the present embodiment, the two semiconductor chips  40   a  and  40   b  have substantially the same planar shape, in particular, the rectangular planar shape. Further, the two semiconductor chips  40   a  and  40   b  have substantially the same size and substantially the same thickness. The semiconductor chips  40   a  and  40   b  are arranged at substantially the same height in the Z direction, and are aligned side by side in the X direction. 
     As shown in  FIG. 20 , a main terminal group  72  is provided by two or more main terminals  70  that are continuously aligned in the X direction. The semiconductor device  20  includes, as the main terminal group  72 , a main terminal group  72   a  corresponding to the semiconductor chip  40   a  and a main terminal group  72   b  corresponding to the semiconductor chip  40   b . At least a part of each main terminal  70  included in the main terminal group  72   a  is arranged in an area A 1   a  that is defined between, in the X direction, extension lines EL 1   a  and EL 2   a  extending from opposite end surfaces  44   a  and  45   a  of the semiconductor chip  40   a . At least a part of each main terminal  70  included in the main terminal group  72   b  is arranged in an area A 1   b  that is defined between, in the X direction, extension lines EL 1   b  and EL 2   b  extending from opposite end surfaces  44 b and  45 b of the semiconductor chip  40   b.    
     The semiconductor device  20  includes five main terminals  70 . Specifically, the five main terminals  70  include two main terminals  70 C and three main terminals  70 E. The widths W 1  of the main terminals  70  are equal to each other, and the thicknesses of the main terminals  70  are equal to each other. Also, the intervals P 1  of the main terminals  70  are equal to each other. The main terminal  70 E in the middle is arranged outside the areas A 1   a  and A 1   b . The main terminal group  72   a  includes two main terminals  70 C and  70 E arranged adjacent to the semiconductor chip  40   a  than the main terminal  70 E in the middle in the X direction. The main terminal group  72   b  includes two main terminals  70 C and  70 E arranged adjacent to the semiconductor chip  40   b  than the main terminal  70 E in the middle in the X direction. 
     Further, the main terminals  70 C and  70 E included in the main terminal group  72   a  are entirely located in the area A 1   a . Similarly, the main terminals  70 C and  70 E included in the main terminal group  72   b  are entirely located in the area A 1   b . The five main terminals  70  are symmetrically arranged with respect to a center line CLm passing through an elemental center of the two semiconductor chips  40 . The elemental center is a center position between the centers of the semiconductor chips  40   a  and  40   b  in the alignment direction, and the center line CLm is a virtual line that is orthogonal to the alignment direction and passes through the elemental center line CL. 
     As described above, in the semiconductor device  20  in which the multiple semiconductor chips  40  are connected in parallel, the main terminal  70 C and the main terminal  70 E are alternately arranged. The lateral surfaces of the adjacent main terminals  70 C and  70 E face each other. In this way, since the main terminals  70  have the plural number of lateral surfaces, i.e., four lateral surfaces facing each other between the main terminals  70 C and the main terminals  70 E, the inductance can be effectively reduced. At least a part of each of the main terminals  70 C and  70 E included in the main terminal group  72   a  is arranged in the area A 1   a . Therefore, the current paths between the main terminals  70 C and  70 E included in the main terminal group  72   a  and the main electrodes of the semiconductor chip  40   a  can be simplified and hence the inductance can be reduced. Likewise, at least a part of each of the main terminals  70 C and  70 E included in the main terminal group  72   b  is arranged in the area Alb. Therefore, the current paths between the main terminals  70 C and  70 E included in the main terminal group  72   b  and the main electrodes of the semiconductor chip  40   b  can be simplified and hence the inductance can be reduced. Accordingly, the inductance of the main circuit wiring can be reduced, as compared with the conventional structure. 
     The main terminals  70  of the odd number are symmetrically arranged with respect to the center line CLm of the two semiconductor chips  40 . In other words, the lateral surface facing portions are symmetrically arranged with respect to the center line CLm. Therefore, the main currents of the semiconductor chips  40   a  and  40   b  flow symmetrically with respect to the center line CLm. That is, the inductance of the semiconductor chip  40   a  and the inductance of the semiconductor chip  40   b  are substantially equal. In this way, since the inductances are equal to each other, current imbalance can be reduced. 
     Although the example in which the two semiconductor chips  40  are connected in parallel has been described, the configuration of the present embodiment is not limited to such an example. The present embodiment may be applied to the configuration in which three or more semiconductor chips  40  are connected in parallel. Also, the number of the main terminals  70  is not limited particularly. Each of the main terminal groups  72  may be provided by two or more main terminals  70  including the main terminals  70 C and  70 E. For example, the semiconductor device  20  may have the seven main terminals  70 , and each of the main terminal groups  72   a  and  72   b  may be provided by three main terminals  70 . The connecting portion  96  ( 86 C,  86 E) shown in  FIGS. 16 to 18  may be combined. 
     The example in which the switching element and the diode are integrally formed into the same semiconductor chip  40  has been described. However, the present embodiment is not limited to such a configuration. The switching element and the diode may be formed in separate chips. The example in which the semiconductor device  20  has the terminal members  60  as for a double-sided heat radiation structure has been described. However, the present embodiment is not limited to such a configuration. The semiconductor device  20  may not have the terminal members  60 . For example, in place of the terminal members  60 , the conductive member  50 E may have protrusions protruding toward the emitter electrodes  42 . The example in which the heat radiation surfaces  54 C and  53 E are exposed from the sealing resin body  30  has been described. Alternatively, the heat radiation surfaces  54 C and  54 E may not expose from the sealing resin body  30 . For example, the heat radiation surfaces  54 C and  54 E may be covered with an insulating member (not shown). The sealing resin body  30  may be formed in a state where the insulating member is attached to the heat radiation surfaces  54 C and  54 E. 
     (Power Module) 
     An example of a power module  110  applicable to the electric power conversion device  5  of the present embodiment will be described. The power module  110  forms the parallel circuit  11  of one set, as described above. 
     As shown in  FIGS. 21 to 27 , the power module  110  includes a semiconductor device  20 , a cooling unit  120 , the capacitor C 1 , a P bus bar  130 , an N bus bar  140 , an output bus bar  150 , a drive substrate  160 , and an external connection terminal  170 , and a protective member  180 . Although  FIG. 21  and  FIGS. 23 to 26  are plan views, internal elements are shown by solid lines so that the internal elements of the protective member  180  are easily understood.  FIG. 27  is a schematic diagram explaining the connections of the semiconductor device  20 , the capacitor C 1 , and the respective bus bars  130 ,  140 , and  150 . 
     The semiconductor device  20  has the  1 -in- 1  package structure as described above. The power module  110  includes the two semiconductor devices  20 . One semiconductor device  20  forms the upper arm  10 U, and the other semiconductor device  20  forms the lower arm  10 L. That is, the semiconductor devices  20  include a semiconductor device  20 U forming the upper arm  10 U, and a semiconductor device  20 L forming the lower arm  10 L. The semiconductor devices  20 U and  20 L have substantially the same basic configurations. Each of the semiconductor devices  20 U and  20 L includes seven main terminals  70 , specifically, three main terminals  70 C and four main terminals  70 E. The main terminals  70 C and  70 E are alternately arranged in the X direction. Hereinafter, the semiconductor chip  40  included in the semiconductor device  20 U and forming the upper arm  10 U is referred to as a semiconductor chip  40 U, and the semiconductor chip  40  included in semiconductor device  20 L and forming the lower arm  10 L is referred to as a semiconductor chip  40 L. 
     The semiconductor device  20 L has the same structure as that shown in  FIG. 12 . The main terminal  70 C has the longer projection length from the sealing resin body  30  than that of the main terminal  70 E. The semiconductor device  20 U has the reversed structure from the semiconductor device  20 L. The main terminal  70 E has the longer projection length from the sealing resin body  30  than that of the main terminal  70 C. As described above, the main terminal  70 E is longer than the main terminal  70 C in the semiconductor device  20 U, whereas the main terminal  70 C is longer than the main terminal  70 E in the semiconductor device  20 L. The main terminal  70 C of the semiconductor device  20 U and the main terminal  70 E of the semiconductor device  20 L have the same length. The main terminal  70 E of the semiconductor device  20 U and the main terminal  70 C of the semiconductor device  20 L have the same length. 
     The semiconductor devices  20 U and  20 L are aligned in the X direction, and a predetermined gap is provided between the semiconductor devices  20 U and  20 L. That is, the semiconductor devices  20 U and  20 L are aligned in a direction orthogonal to the plate thickness direction of the semiconductor chip  40 , that is, the Z direction. The semiconductor devices  20 U and  20 L are aligned such that the respective one surfaces  31  of the sealing resin bodies  30  are on the same side and the respective rear surfaces  32  are on the same side in the Z direction. Between the semiconductor devices  20 U and  20 L, the one surfaces  31  are substantially flush with each other in the Z direction, and the rear surfaces  32  are substantially flush with each other in the Z direction. 
     In each of the semiconductor devices  20 U and  20 L, the projected portions of signal terminals  80  projecting from the sealing resin body  30  each have substantially an L shape. The projected portion of each signal terminal  80  has one bend portion of approximately 90 degrees. In the projected portion of the signal terminal  80 , a portion from the base of the sealing resin body  30  to the bent portion extends in the Y direction, and a portion from the bent portion to the projecting tip end extends in the Z direction and toward a side opposite to the capacitor C 1 . 
     The cooling unit  120  mainly cools the semiconductor devices  20 . The cooling unit  120  is formed of a material having excellent thermal conductivity, for example, an aluminum-based material. The cooling unit  120  includes a supply pipe  121 , a discharge pipe  122 , and a heat exchange part  123 . Because the cooling unit  120  is provided in the power module  110 , the cooling unit  120  is also referred to as an in-module cooling unit. 
     The heat exchange part  123  is made of a pair of plates  124  and  125 . The plates  124  and  125  are each made by using a thin metal plate having substantially a rectangular planar shape. At least one of the plate  124  and the plate  125  has a bulged-shape, such as a shallow pot-like bottomed shape, as being pressed from the plate shape. In the present example, the plate  124  has the pot-like bottomed shape. Outer peripheral portions of the plates  124  and  125  are fixed to each other, such as by swage, and are entirely joined to each other such as by brazing, so that a flow path  126  is formed between the plate  124  and the plate  125 . 
     The heat exchange part  123  has a flat tubular body as a whole. The cooling unit  120  has two heat exchange parts  123 . The heat exchange parts  123  are arranged in two stages in the Z direction. The two semiconductor devices  20 U and  20 L are held between the two heat exchange parts  123  in a state where the two semiconductor devices  20 U and L are aligned in the X direction. The two heat exchange parts  123  are arranged so that the plates  124  are opposed each other. One of the two heat exchange parts  123  is arranged adjacent to the one surfaces  31  of the semiconductor devices  20 , and the other of the two heat exchange parts  123  is arranged adjacent to the rear surfaces  32  of the semiconductor devices  20 . In the configuration where the heat radiation surfaces  54 C and  54 E are exposed from the sealing resin body  30 , as described above, an electrically insulating member such as grease, a ceramic plate or a resin member is arranged between the semiconductor devices  20  and the plate  124  of each heat exchange part  123 . 
     The supply pipe  121  is a tubular body defining a flow path therein, and extends in the Z direction. The supply pipe  121  is provided at one end of the heat exchange part  123 , which has substantially the rectangular plane shape, in the X direction, on a side adjacent to the main terminals  70  in the Y direction. The supply pipe  121  is connected to each of the heat exchange parts  123  so that the flow path of the supply pipe  121  is in communication with the flow paths  126  of the heat exchange parts  123 . One end of the supply pipe  121  is open in the Z direction, and the opposite end of the supply pipe  121  is connected to the heat exchange part  123  on the second stage. The flow path  126  of the heat exchange part  123  on the first stage is in communication with the flow path of the supply pipe  121  at a middle position of the extension of the supply pipe  121 . The heat exchange part  123  on the first stage is adjacent to the open ends of the supply pipe  121  and a discharge pipe  122 , and the heat exchange part  123  on the second stage is further from the open ends of the supply pipe  121  and the discharge pipe  122 . A part of the supply pipe  121  including the open end projects outside from the protective member  180 . 
     The discharge pipe  122  is a tubular body defining a flow path therein, and extends in the Z direction. The discharge pipe  122  is provided at an end of the heat exchange part  123 , which has substantially the rectangular plane shape, opposite to the supply pipe  121  in the X direction, on a side adjacent to the signal terminals  80  in the Y direction. The discharge pipe  122  is connected to each of the heat exchange parts  123 , and the flow path of the discharge pipe  122  is in communication with the flow paths  126  of the heat exchange parts  123 . The discharge pipe  122  is open in the Z direction on the same side as the supply pipe  121 . An end of the discharge pipe  122  opposite to the open end is connected to the heat exchange part  123  on the second stage. The flow path  126  of the heat exchange part  123  on the first stage is in communication with the flow path of the discharge pipe  122  at a middle position of the extension of the discharge pipe  122 . A part of the discharge pipe  122  including the open end projects outside from the protective member  180 . 
     As shown by a long dashed double-dotted line arrow in  FIG. 26 , the refrigerant flows into the flow paths  126  of the heat exchange parts  123  from the supply pipe  121 , and spreads inside the flow paths  126 . The refrigerant is then discharged from the discharge pipe  122 . As described above, the supply pipe  121  and the discharge pipe  122  are located at diagonal positions of the substantially rectangular plane shape of the heat exchange parts  123 . Since the supply pipe  121  and the discharge pipe  122  are provided at the diagonal positions, the semiconductor chips  40 U and  40 L located between the supply pipe  121  and the discharge pipe  122  with respect to the X direction and the Y direction can be effectively cooled. Although not shown, an inner fin may be provided inside the flow path  126  of the heat exchange part  123 . The inner fin is a metal plate that is bent and formed into a wavy shape. As the inner fin is provided, heat transfer between each of the plates  124  and  125  and the refrigerant flowing through the flow path  126  can be enhanced. 
     As the refrigerant flowing through the flow path  126 , a phase transition refrigerant such as water or ammonia or a non-phase transition refrigerant such as ethylene glycol can be used. The cooling unit  120  mainly cools the semiconductor devices  20 . However, in addition to the cooling function, the cooling unit  120  may have a heating function when the environmental temperature is low. In such a case, the cooling unit  120  may be referred to as a temperature adjusting device. The refrigerant may be referred to as a heat medium. 
     The capacitor C 1  is arranged in the vicinity of the set of the semiconductor devices  20 U and  20 L of the power module  110 . As described above, it is sufficient that the capacitor C 1  has, at least, a function of supplying the electric charges necessary for the switching. Therefore, the capacitance of the capacitor C 1  is set to, for example, 10 μF to 20 μF. The capacitor C 1  has substantially a rectangular parallelepiped shape. The capacitor C 1  has a flat shape, in which the thickness, that is, a length in the Z direction is sufficiently smaller than a length in the X direction and a length in the Y direction. As described, the capacitor C 1  is small in size. As the capacitor C 1 , for example, a film capacitor can be used. 
     In the present example, the capacitor C 1  has a rectangular planar shape in which the length the in the X direction is longer than that in the Y direction. In a projection view in the Z direction, most part of the capacitor C 1  is located at a position overlapping with the heat exchange part  123  of the cooling unit  120 . In the same projection view, the most part of the capacitor C 1  overlaps with the most part of the semiconductor devices  20 U and  20 L, specifically, the semiconductor devices  20 U and  20 L excluding the projected portions of the main terminals  70  and the projected portions of the signal terminals  80 . As such, the capacitor C 1  is aligned with the semiconductor devices  20 U and  20 L in the Z direction. The capacitor C 1  having the rectangular planar shape is arranged at a position where the both ends in the X direction do not overlap with the cooling unit  120 , that is, arranged so that the both ends in the X direction are located outside the cooling unit  120 . 
     The capacitor C 1  is arranged so that the heat exchange part  123  is interposed between the capacitor C 1  and the semiconductor devices  20 . The capacitor C 1  is arranged on the opposite side to the semiconductor device  20  with respect to the heat exchange part  123 . In the present example, the capacitor C 1  is arranged on the opposite side to the semiconductor device  20  with respect to the heat exchange part  123  of the first stage. That is, the capacitor C 1  is located adjacent to the open ends of the supply pipe  121  and the discharge pipe  122  than the closed ends of the supply pipe  121  and the discharge pipe  122 . The capacitor C 1  is located at a position closer to the semiconductor device  20  than the open ends of the supply pipe  121  and the discharge pipe  122  in the Z direction. The capacitor C 1  has a positive electrode terminal (not shown) for external connection on a surface facing the heat exchange part  123  in the Z direction, and a negative electrode terminal (not shown) for external connection on a surface opposite to the surface on which the positive electrode terminal is arranged. 
     The P bus bar  130 , the N bus bar  140 , and the output bus bar  150  are metal plate members each including a metal having excellent conductivity such as copper, for example. In the present example, the thickness of each bus bar is almost uniform. The P bus bar  130 , the N bus bar  140 , and the output bus bar  150  have substantially the same thickness. As the metal plate member, a plate of which thicknesses is partially different can be used. The P bus bar  130 , the N bus bar  140 , and the output bus bar  150  are electrically separated from the cooling unit  120 . 
     The P bus bar  130  includes a connection portion  131 , a common wiring portion  132 , and a parallel wiring portion  133 . The connection portion  131  is a portion connected to the positive electrode terminal of the capacitor C 1 . In the present example, in the projection view of the P bus bar  130  in the Z direction, the entire portion overlapping with the capacitor C 1  is the connection portion  131 . Although not shown, the connection portion  131  may be arranged at the portion overlapping with the capacitor C 1  in the projection view in the X direction or the Y direction, that is, on the lateral surface of the capacitor C 1 . The common wiring portion  132  extends from one end of the connection portion  131  in the Y direction. The common wiring portion  132  is a portion of the P bus bar  130  that functions as the above-described common wiring  11 P. As a result, the one upper and lower arm circuit  10  included in the power module  110  and the capacitor C 1  are not individually connected to the above-described VH line  12 H, but are commonly connected to the above-described VH line  12 H. The common wiring portion  132  has a shorter length in the X direction, that is, a shorter width than the connection portion  131 . The common wiring portion  132  connects to a central portion of the connection portion  131  in the X direction. The common wiring portion  132  is substantially flush with the connection portion  131  and extends in the Y direction. A part of the common wiring portion  132  projects to the outside of the protective member  180 . 
     The parallel wiring portion  133  functions as, at least, a wiring electrically connecting the positive electrode terminal of the capacitor C 1  and the upper arm  10 U of the upper and lower arm circuit  10 , that is, a wiring connecting the upper and lower arm circuit  10  and the capacitor C 1  in parallel. In the present example, further, the parallel wiring portion  133  also functions as a wiring electrically connecting the upper arm  10 U to the common wiring  11 P, that is, to the common wiring portion  132 . The parallel wiring portion  133  extends from an end of the connection portion  131 , the end being opposite to the common wiring portion  132 . 
     The parallel wiring portion  133  has a width narrower than that of the connection portion  131 . The parallel wiring portion  133  is extended with a constant width. The parallel wiring portion  133  is located on one side of the capacitor C 1  with respect to a center line CL 1  (see  FIG. 23 ) bisecting the capacitor C 1  in the X direction, so as not to extend over the center line CL 1  in the X direction. The parallel wiring portion  133  connects to the connection portion  131  on the side adjacent to semiconductor device  20 U (semiconductor chip  40 U) in the alignment direction of the semiconductor devices  20 U and  20 L. 
     The parallel wiring portion  133  has substantially an L shape. The parallel wiring portion  133  has a parallel portion  134  extending in the Y direction from a boundary portion with the connection portion  131  and a bent portion  135  that is bent with respect to the parallel portion  134  and extend in the Z direction. Therefore, the parallel portion  134  is also referred to as a Y direction extension portion. The bent portion  135  is also referred to as a Z direction extension portion. The parallel portion  134  extends in the Y direction towards the opposite side to the common wiring portion  132 . The parallel portion  134  is substantially flush with the connection portion  131  and extends in the Y direction. 
     In the projection view in the Z direction, the parallel portion  134  overlaps with at least a part of each of the seven main terminals  70 C and  70 E of the semiconductor device  20 U. The parallel portion  134  extends up to substantially the same position as the projection tip end portions of the main terminals  70 C of the semiconductor device  20 U, and overlaps with the entire projected portions of the three main terminals  70 C in the projection view. The four main terminals  70 E extend up to a position that is farther from the capacitor C 1  than the parallel portion  134 . 
     The bent portion  135  extends towards the opposite side to the capacitor C 1  in the Z direction. The bent portion  135  has a plate thickness direction to be substantially parallel to the Y direction. In the present example, the entirety of the bent portion  135  is a facing portion  135   a  facing the output bus bar  150  in the Y direction. The surface of the facing portion  135   a  and the surface of the output bus bar  150  in the plate thickness direction, that is, the plate surfaces thereof face each other. At the tip end of the facing portion  135   a , that is, the tip end of the extension of the parallel wiring portion  133 , projections  136  are formed so that the main terminals  70 C of the semiconductor device  20 U are connected thereto. The projections  136  are correspondingly provided for the main terminals  70 . The main terminals  70 C are joined by laser welding or the like in a state where the main terminals  70 C are placed on end surfaces of the corresponding projections  136 . When the projections  136  are provided in this way, the main terminals  70 E pass through the recessed portions where the projections  136  are not provided, so that the contact between the P bus bar  130  and the main terminals  70 E can be suppressed. 
     The N bus bar  140  includes a connection portion  141 , a common wiring portion  142 , and a parallel wiring portion  143 . The connection portion  141  is a portion connected to the negative electrode terminal of the capacitor C 1 . In the present example, in the projection view in the Z direction, the entire portion overlapping with the capacitor C 1  is the connection portion  141 . Similarly to the connection portion  131 , the connection portion  141  may be provided at the portion overlapping with the capacitor C 1  in the projection view in the X direction or the Y direction, that is, on the lateral surface of the capacitor C 1 . The capacitor C 1  and the connection portions  131  and  141  arranged on both surfaces of the capacitor C 1  are electrically separated from the cooling unit  120 . An electrical insulation member is provided between the capacitor C 1  including the connection portions  131  and  141  and the cooling unit  120 . 
     The common wiring portion  142  extends from one end of the connection portion  141  in the Y direction. The common wiring portion  142  is a portion that functions as the common wiring  11 N in the N bus bar  140 . As a result, the one upper and lower arm circuit  10  of the power module  110  and the capacitor C 1  are not individually connected to the N line  13 , but are commonly connected to the N line  13 . The width of the common wiring portion  142  is narrower than the width of the connection portion  141 , and substantially the same as that of the common wiring portion  132 . The common wiring portion  142  connects to a central portion of the connection portion  141  in the X direction. The common wiring portion  142  is substantially flush with the connection portion  141  and extends in the Y direction. A part of the common wiring portion  132  projects to the outside of the protective member  180 . 
     The common wiring portions  132  and  142  substantially coincide with each other in the projection view in the Z direction. The common wiring portions  132  and  142  are arranged so as to face each other with an interval substantially equal to the thickness of the capacitor C 1  in the Z direction. As a result, the inductance of the main circuit wiring can be suppressed. 
     The parallel wiring portion  143  at least functions as a wiring electrically connecting the negative electrode terminal of the capacitor C 1  and the lower arm  10 L of the upper and lower arm circuit  10 , that is, a wiring connecting the upper and lower arm circuit  10  and the capacitor C 1  in parallel. Further, in the present example, the parallel wiring portion  143  also functions as a wiring electrically connecting the lower arm  10 L to the common wiring  11 N, that is, to the common wiring portion  142 . The parallel wiring portion  143  extends from an end of the connection portion  141 , the end being opposite to the common wiring portion  142 . 
     A width of the parallel wiring portion  143  is narrower than that of the connection portion  141 . The parallel wiring portion  143  is extended with a constant width. The parallel wiring portion  143  is arranged on the side opposite to the parallel wiring portion  133  with respect to the center line CL 1  so as not to extend over the center line CL 1  of the capacitor C 1 . The parallel wiring portion  143  connects to the connection portion  141  on the side adjacent to the semiconductor device  20 L (semiconductor chip  40 L) in the alignment direction of the semiconductor devices  20 U and  20 L. 
     The parallel wiring portion  143  has substantially an L shape. The parallel wiring portion  143  includes a parallel portion  144  extending in the Y direction from a boundary portion with the connection portion  141  and a bent portion  145  that is bent with respect to the parallel portion  144  and extends in the Z direction. The parallel portion  144  extends in the Y direction towards the opposite side to the common wiring portion  142 . The parallel portion  144  is substantially flush with the connection portion  141  and extends in the Y direction. The parallel portions  134  and  144  are laterally arranged in the X direction with an interval therebetween for ensuring the electrical insulation. The lateral surfaces of the parallel portions  134  and  144  face each other. As a result, the inductance of the main circuit wiring can be reduced. 
     In the projection view in the Z direction, the parallel portion  144  overlaps with at least a part of each of the seven main terminals  70 C and  70 E of the semiconductor device  20 L. The parallel portion  144  extends up to substantially the same position as the projected tip end portions of the main terminals  70 E of the semiconductor device  20 L, and overlaps with the entire projected portions of the four main terminals  70 E in the projection view. The three main terminals  70 C extend up to a position that is farther from the capacitor C 1  than the parallel portion  144 . The projected tip end portions of the main terminals  70 C of the semiconductor device  20 U and the projected tip end portions of the main terminals  70 E of the semiconductor device  20 L are substantially at the same position in the Y direction. As such, the end of extension of the parallel portion  134  and the end of extension of the parallel portion  144  are located at substantially the same position. 
     The bent portion  145  extends towards the opposite side to the capacitor C 1  in the Z direction. The bent portion  145  has a plate thickness direction to be substantially parallel to the Y direction. The extended tip end of the bent portion  145  is located at substantially the same position as the extended tip end of the bent portion  135  of the P bus bar  130 . The bent portions  135  and  145  are laterally arranged in the X direction with an interval therebetween for ensuring the electrical insulation. The lateral surfaces of the bent portions  135  and  145  face each other. As a result, the inductance of the main circuit wiring can be suppressed. 
     In the present example, the N bus bar  140  is located further from the semiconductor device  20  in the Z direction than the P bus bar  130 . A part of the bent portion  145  is a facing portion  145   a  facing the output bus bar  150  in the Y direction. The plate surface of the facing portion  145   a  and the plate surface of the output bus bar  150  face each other. At the tip end of the facing portion  145   a , that is, the tip end of the extension of the parallel wiring portion  143 , projections  146  are formed so that the main terminals  70 E of the semiconductor device  20 L are connected thereto. The projections  146  are correspondingly provided for the main terminals  70 E. The main terminals  70 E are joined by laser welding or the like in a state where the main terminals  70 E are placed on end surfaces of the corresponding projections  146 . When the projections  146  are provided in this way, the main terminals  70 C pass through the recessed portions where the projections  146  are not provided, so that the contact between the N bus bar  140  and the main terminals  70 C can be suppressed. 
     The parallel wiring portion  133  and the main terminal  70 C of the semiconductor device  20 U connects the positive electrode of the capacitor C 1  to the collector electrode of the upper arm  10 U. The parallel wiring portion  143  and the main terminal  70 E of the semiconductor device  20 L connects the negative electrode of the capacitor C 1  to the emitter electrode of the lower arm  10 L. In this way, the upper and lower arm circuit  10  and the capacitor C are connected in parallel by the parallel wiring portion  133  and the main terminal  70 C of the semiconductor device  20 U, and the parallel wiring portion  143  and the main terminal  70 E of the semiconductor device  20 L, thereby forming the parallel circuit  11 . The common wiring portions  132  and  142  connect the parallel circuit to the VH line  12 H and the N line  13 , which are the electric power lines. 
     The output bus bar  150  is a bus bar for connecting the connection point between the upper arm  10 U and the lower arm  10 L to a three-phase winding of the motor generator. The output bus bar  150  is also referred to as an O bus bar. The output bus bar  150  is arranged on the side adjacent to the main terminals  70  than the signal terminals  80  in the Y direction. The output bus bar  150  has the plate thickness direction in the Y direction, and extends in the X direction without having the bent portion. The output bus bar  150  forms at least a part of the output wiring  15  described above. Note that a current sensor (not shown) may be provided on a periphery of the output bus bar  150 . 
     The output bus bar  150  has a wide width portion  151  having a larger length in the Z direction, that is, a larger width, and a narrow width portion  152  having a smaller width than the wide width portion  151 . The narrow width portion  152  connects to an end of the wide width portion  151 . The narrow width portion  152  is substantially flash with the wide width portion  151 , and extends in the X direction. The wide width portion  151  is entirely located inside of the protective member  180 . A part of the narrow width portion  152  is located inside of the protective member  180 , and a remaining part of the narrow width portion  152  projects outside from the protective member  180 . 
     The wide width portion  151  is arranged to substantially coincide with the area defined, in the X direction, between an end of the parallel wiring portion  143  further from the center line CL 1  and an end of the parallel wiring portion  133  further from the center line CL 1 . The supply pipe  121  is arranged adjacent to the end of the wide width portion  151  in the X direction. The wide width portion  151  is arranged with the predetermined interval from the bent portions  135  and  145  in the Y direction. For example, the predetermined interval substantially corresponds to the length that is obtained by subtracting a plate thickness of the output bus bar  150  from a difference length between the protruded tip ends of the main terminals  70 C and the protruded tip ends of the main terminals  70 E of the semiconductor device  20 U. The wide width portion  151  is arranged in an area in the Z direction from a position overlapping with the capacitor C 1  to the position of the plate  125  of the heat exchange part  123  of the second stage. 
     The wide width portion  151  is formed with a plurality of through holes  153 . The main terminals  70 E of the semiconductor device  20 U and the main terminals  70 C of the semiconductor device  20 L are inserted into the through holes  153 . In the inserted state, the main terminals  70  are connected to the wide width portion  151  (output bus bar  150 ) by a laser welding or the like. The output bus bar  150  has a facing portion  154   p  for facing towards the P bus bar  130  and a facing portion  154   n  for facing towards the N bus bar  140  without overlapping the through holes  153 . The facing portion  154   p  of the output bus bar  150  and the facing portion  135   a  of the P bus bar  130  face each other with the predetermined interval in the Y direction. The facing portion  154   n  of the output bus bar  150  and the facing portion  145   a  of the N bus bar  140  face each other with the predetermined interval in the Y direction. 
     Since the supply pipe  121  exists, the width of the parallel wiring portion  143  is narrower than that of the parallel wiring portion  133 . As a result, the width of the facing portion  145   a  is narrower than that of the facing portion  135   a . However, in the capacitor C 1 , since the negative electrode terminal is arranged on the surface opposite to the heat exchange part  123 , the extension length in the facing portion  145   a  is obtained. The length of the facing portion  145   a  in the Z direction is longer than that of the facing portion  135   a . As a result, the facing area between the facing portion  135   a  and the facing portion  154   p  is substantially equal to the facing area between the facing portion  145   a  and the facing portion  154   n . The inductance can be reduced while suppressing the increase in side in the X direction. 
     The drive substrate  160  is provided by a printed substrate on which an electronic component (not shown) is mounted. The drive substrate  160  is formed with a drive circuit (driver) that receives the drive instruction from the control circuit  9 . The drive substrate  160  corresponds to a circuit board. The drive substrate  160  has substantially a rectangular planar shape. In the present example, in regard to the size of the drive substrate  160 , the length in the X direction is substantially the same as the length of the heat exchange parts  123  of the cooling unit  120  in the X direction, and the length in the Y direction is longer than the length of the heat exchange parts  123  in the Y direction. The drive substrate  160  is arranged so as to overlap with most of the semiconductor devices  20 U and  20 L, in the projection view in the Z direction. Specifically, the drive substrate  160  is arranged so as to overlap with the semiconductor devices  20 U and  20 L excluding the part of the main terminals  70 . The part of the main terminals  70 , the bent portions  135  and  145 , and the output bus bar  150  are arranged so as not to overlap with the drive substrate  160  in the Y direction. On the side opposite to the main terminals  70 , the common wiring portions  132  and  142  project more to outside than the drive substrate  160 . 
     To the drive substrate  160 , the signal terminals  80  of the semiconductor devices  20  are connected. In the present example, the drive substrate  160  is formed with multiple through holes (not shown), and the signal terminals  80  are respectively inserted into the through holes and mounted thereon. As a result, the drive signal from the drive circuit formed in the drive substrate  160  is output through the signal terminals  80 . The signal terminals  80  are aligned in the X direction. The multiple signal terminals  80  are aligned in one row in the X direction in an area adjacent to an end of the drive substrate  160  in the Y direction, and insert-mounted on the drive substrate  160 . 
     The external connection terminals  170  are terminals for electrically connecting a control substrate  290 , on which the control circuit  9  is formed, and the drive substrate  160 . The control substrate  290  will be described later. The multiple external connection terminals  170  are connected to the drive substrate  160 . In the present example, the drive substrate  160  is formed with multiple through holes (not shown), and the external connection terminals  170  are respectively insert into the through holes and mounted on the drive substrate  160 . A part of the external connection terminals  170  transmits the drive instruction of the control circuit  9  to the drive circuit portion of the drive substrate  160 . 
     The external connection terminals  170  each have substantially an L shape. The external connection terminal  170  has one bent portion of approximately 90 degrees. Of the external connection terminal  170 , a portion from the connection portion with the drive substrate  160  to the bent portion extends in the Z direction, and a portion from the bent portion to the tip end extends toward the common wiring portions  132  and  142  in the Y direction. A predetermined range from the tip end projects outside from the protective member  180 . 
     The protective member  180  protects other elements forming the power module  110 . The protective member  180  forms an outer shape of the power module  110 . As the protective member  180 , a sealing resin body integrally sealing the other elements, a case molded beforehand, or the like can be used. In a case where the protective member  180  is provided by the case, a potting material or the like may be used together in order to enhance the protection. In the present example, as the protective member  180 , the sealing resin body is used. The sealing resin body is molded using a resin material such as an epoxy resin, and thus is also referred to as a molded resin or a resin molded body. The sealing resin body is, for example, formed by a transfer molding method. 
     The protective member  180  has one surface  181  and a rear surface  182  opposite to the one surface  181  in the Z direction. The one surface  181  and the rear surface  182  are plane surface orthogonal to the Z direction. The protective member  180  of the present example has a substantially truncated quadrangular pyramid shape. Therefore, the protective member  180  has four lateral surfaces  183  to  186 . When the one surface  181  is defined as a reference surface, each of the lateral surfaces  183  to  186  is an inclined surface defining an acute angle with respect to the one surface  181 . 
     Components of the power module  110  are arranged, in a direction from the one surface  181  toward the rear surface  182 , in a stated order of the connection portion  141  of the N bus bar  140 , the capacitor C 1 , the connection portion  131  of the P bus bar  130 , the heat exchange part  123  of the first stage, the semiconductor device  20 , the heat exchange part  123  of the second stage, and the drive substrate  160 . The supply pipe  121  and the discharge pipe  122  project from the one surface  181  to the outside of the protective member  180 . Nothing projects from the rear surface  182 . Although not shown, the components may be arranged, in a direction from the one surface  181  toward the rear surface  182 , in an order of the drive substrate  160 , the heat exchange part  123  of the first stage, the semiconductor device  20 , the heat exchange part  123  of the second stage, the connection portion  141  of the N bus bar  140 , the capacitor C 1 , and the connection portion  131  of the P bus bar  130 . 
     The common wiring portions  132  and  142  of the P bus bar  130  and the N bus bar  140  project, in the Y direction, from the lateral surface  183  adjacent to the signal terminals  80  to the outside of the protective member  180 . From the lateral surface  183 , the external connection terminals  170  also project. As shown in  FIG. 21 , the common wiring portions  132  and  142  are arranged between the external connection terminals  170  of the semiconductor device  20 U and the external connection terminals  170  of the semiconductor device  20 L, in the X direction. As shown in  FIG. 22 , the external connection terminals  170  project at positions adjacent to the rear surface  182 , and the common wiring portions  132  and  142  project at positions adjacent to the one surface  181 . Nothing projects from the lateral surface  184  that is opposite to the lateral surface  183 , that is, from the lateral surface  184  adjacent to the main terminals  70 . The narrow width portion  152  of the output bus bar  150  projects to the outside of the protective member  180  in the X direction from a lateral surface  185  adjacent to the semiconductor device  20 U. Nothing projects from the lateral surface  186  that is opposite to the lateral surface  185 , that is, from the lateral surface adjacent to the semiconductor device  20 L. 
     As described above, only the supply pipe  121  and the discharge pipe  122  project from the one surface  181  of the protective member  180 . Therefore, in a case where a cooling unit different from the power module  110  is arranged adjacent to the one surface  181  so as to cool the power module  110 , the cooling unit can be easily connected to the supply pipe  121  and the discharge pipe  122 . Since the common wiring portions  132  and  142  project from the lateral surface different from the lateral surface from which the output bus bar  150  projects, the connection with the electric power lines or the three-phase winding can be simplified. 
     In this case, the surge generated in accordance with the switching of the upper and lower arm circuit  10  increases with an increase in the amount of current change (current change rate) per unit time, or with an increase in the wiring inductance. In the power module  110  described above, the wiring inductance is reduced, to thereby reduce the above-described surge. Hereinafter, of the structure of the power module  110 , a structure that reduces the wiring inductance to enable the reduction of the surge will be described. 
       FIG. 28  is a circuit diagram obtained by extracting the inverter  7 , the smoothing capacitor C 2 , and the motor generator  3  from the equivalent circuit diagram of  FIG. 1 , and shows the wiring inductance parasitic on the circuit. As shown in a dashed dotted line of  FIG. 28 , the power modules  110  of the respective phases are connected in parallel between the P line  12  and the N line  13 , as described above. 
     On the P line  12 , the wiring inductance generated in a portion between connection portions to which the power modules  110  are connected is referred to as an interphase upper inductance L 2 P. Specifically, the wiring inductance generated in an interphase portion of the P line  12  defined between a connection portion with the common wiring portion  132  of the U phase and a connection portion with the common wiring portion  132  of the V phase is the interphase upper inductance L 2 P. Further, the wiring inductance generated in an interphase portion of the P line  12  defined between a connection portion with the common wiring portion  132  of the V phase and the a connection portion with the common wiring portion  132  of the W phase is the interphase upper inductance L 2 P. An impedance generated in proportion to the interphase upper inductance L 2 P is referred to as an interphase upper impedance. 
     On the N line  13 , the wiring inductance generated in a portion between connection portions to which the power modules  110  of the respective phases are connected is referred to as an interphase lower inductance L 2 N. Specifically, the wiring inductance generated in an interphase portion of the N line  13  defined between a connection portion with the common wiring portion  142  of the U phase and a connection portion with the common wiring portion  142  of the V phase is the interphase lower inductance L 2 N. The wiring inductance generated at an interphase portion of the N line  13  defined between a connection portion with the common wiring portion  142  of the V phase and a connection portion with the common wiring portion  142  of the W phase is the interphase lower inductance L 2 N. An impedance generated in proportion to the interphase lower inductance L 2 N is referred to as an interphase lower impedance. 
     A wiring inductance of the electric path from the positive electrode terminal of the capacitor C 1  to the upper arm  10 U inside the power module  110  is referred to as an in-phase upper inductanc L 1 P. Specifically, the wiring inductance generated on the parallel portion  134  and the bent portion  135  of the P bus bar  130  is the in-phase upper inductance L 1 P. A wiring of a portion where the in-phase inductance L 1 P is formed is referred to as an upper wiring  11 Pa. An impedance generated in proportion to the in-phase upper inductance L 1 P is referred to as an in-phase upper impedance. 
     A wiring inductance of the electric path from the negative electrode terminal of the capacitor C 1  to the lower arm  10 L inside the power module  110  is referred to as an in-phase lower inductance L 1 N. Specifically, the wiring inductance generated on the parallel portion  144  and the bent portion  145  of the N bus bar  140  is the in-phase lower inductance L 1 N. A wiring of a portion where the in-phase lower in-phase L 1 N is formed is referred to as a lower wiring  11 Na. An impedance generated in proportion to the in-phase lower inductance L 1 N is referred to as an in-phase lower impedance. 
     In  FIG. 28 , each impedance has been described in regard to the inverter  7  as an example. However, each impedance corresponds also to the inverter and the converter connected in parallel with the inverter  7 , as described hereinafter. That is, the power module  110  provided in a first phase among the phases is referred to as a first power module, and the power module  110  provided in a second phase is referred to as a second power module. An impedance of an electric path from the positive electrode terminal of the capacitor C 1  to the upper arm  10 U in the first power module corresponds to the in-phase upper impedance. An impedance of an electric path from the positive electrode terminal of the capacitor C 1  in the first power module to the upper arm  10 U in the second power module corresponds to the interphase upper impedance. An impedance of an electric path from the negative electrode terminal of the capacitor C 1  to the lower arm  10 L in the first power module corresponds to the in-phase lower impedance. An impedance of an electric path from the negative electrode terminal of the capacitor C 1  in the first power module to the lower arm  10 L in the second power module corresponds to the interphase lower impedance. 
     A length of the wiring for forming the interphase upper inductance L 2 P is longer than a length of the wiring for forming the in-phase upper inductance L 1 P. Therefore, the interphase upper inductance L 2 P is larger than the in-phase upper inductance L 1 P, and the interphase upper impedance is larger than the in-phase upper impedance. A length of the wiring for forming the interphase lower inductance L 2 N is longer than a length of the wiring for forming the in-phase upper inductance L 1 P. Therefore, the interphase lower inductance L 2 N is larger than the in-phase lower inductance L 1 N, and the interphase lower impedance is larger than the in-phase lower impedance. Each of the interphase upper inductance L 2 P and the interphase lower inductance L 2 N is larger than a value obtained by adding the in-phase lower inductance L 1 N to the in-phase upper inductance L 1 P. 
     An arrow Y 1  in  FIG. 28  indicates a path in which the surge voltage is absorbed by the capacitor C 1  in a closed loop circuit formed in the parallel circuit  11  in the V phase. This surge voltage is generated when the switching elements Q 1  and Q 2  in the V phase are turned on and turned off. Similarly, also in the U phase or the W phase, the surge voltage is absorbed by the capacitor C 1  as shown by the arrow Y 1 . The surge voltage generated and absorbed in the same phase as described above is also referred to as a self-surge voltage in the following description. 
     The closed loop circuit is a circuit formed by the above-described parallel circuit  11 . In the closed loop circuit, the positive electrode terminal of the capacitor C 1 , the upper wiring  11 Pa, the upper and lower arm circuit  10 , the lower wiring  11 Na, and the negative electrode of the capacitor C 1  are connected in series in this order. The closed loop circuit does not include the electric power line. The closed loop circuit is the path in which the surge voltage is absorbed as described above, and is also referred to as a path in which the electric charges required for the switching of the switching elements Q 1  and Q 2  are supplied from the capacitor C 1  to the switching elements Q 1  and Q 2 . 
     The closed loop circuit is a circuit that does not include the common wirings  11 P and  11 N. In other words, the P bus bar  130  is branched into a portion shown by a long dashed double-dotted line in  FIG. 28  for forming the upper wiring  11 Pa and a portion for forming the common wiring  11 P. The common wiring  11 P of the P bus bar  130  is also referred to as an upper electric power wiring that connects the P line  12  and the upper wiring  11 Pa. The N bus bar  140  is branched into a portion shown by a long dashed double-dotted line in  FIG. 28  for forming the lower wiring  11 Na and a portion for forming the common wiring  11 N. The common wiring  11 N of the N bus bar  140  is also referred to as a lower electric power wiring that connects the N line  13  and the lower wiring  11 Na. 
     An arrow Y 2  in  FIG. 28  indicates a path when the self-surge voltage generated in the V phase propagates from the closed loop circuit in the V phase to the closed loop circuit in the W phase via the electric power line. The surge voltage that interferes with the multiple upper and lower arm circuits  10  in such a manner is also referred to as an interference surge voltage in the following description. Similarly to the interference surge voltage propagating between the V phase and the W phase, the interference voltage may occur between the V phase and the U phase or between the W phase and the U phase. 
     However, since the interphase upper inductance L 2 P is sufficiently larger than the in-phase upper inductance L 1 P, the interference surge voltage propagated from another phase to the own phase hardly occurs. The interference surge voltage is extremely smaller than the self-surge voltage. 
     When the electric charges are supplied to the upper and lower arm circuit  10  connected in parallel, the electric charges are instantaneously supplied from the smoothing capacitor C 2  to the capacitor C 1 . As a result, the capacitor C 1  can be made in a state that can supply the electric charges again. 
     Next, effects of the above-described power module  110  will be described. 
     The power module  110  includes the upper and lower arm circuit  10 , the capacitor C 1 , the upper wiring  11 Pa, the lower wiring  11 Na, the common wiring  11 P as the upper electric power wiring, and the common wiring  11 N as the lower electric power wiring. The upper wiring  11 Pa connects the positive electrode terminal of the capacitor C 1  and the upper arm  10 U. The lower wiring  11 Na connects the negative electrode terminal of the capacitor C 1  and the lower arm  10 L. The common wirings  11 P and  11 N respectively connect the upper wiring  11 Pa and the lower wiring  11 Na to the electric power lines. 
     Accordingly, the power module  110  forms the closed loop circuit that does not include the electric power line. Therefore, when the electric charges required for the switching of the upper and lower arm circuit  10  are supplied from the capacitor C 1 , the electric charge supply path does not include the electric power line. As such, the wirings of the path, that is, the upper wiring  11 Pa and the lower wiring  11 Na can be shortened. On the other hand, when the capacitor C 1  is abolished contrary to the present embodiment, the electric charges required for the switching are supplied from the smoothing capacitor C 2 . In such a case, since the electric power path for supplying the electric charges from the smoothing capacitor C 2  to the upper and lower arm circuit  10  includes the electric power line, the electric path cannot be sufficiently shortened. 
     As described above, according to the above described power module  110 , it is possible to easily shorten the wiring length that is one factor of the surge voltage occurrence, as compared with the configuration in which the capacitor C 1  is abolished. Therefore, the wiring inductances L 1 P and L 1 N related to the self-surge voltage can be reduced, and the self-surge voltage generated at the upper and lower arm circuit  10  can be reduced. Moreover, since the above-described closed loop circuit does not include the electric power line, the self-surge voltage is less likely to be superimposed on the self-surge voltage. Therefore, it is less likely that the self-surge voltage will interfere with the other upper and lower arm circuits  10  through the electric power line. 
     The power module  110 , which is capable of reducing the surge voltage as described above, is provided for each of the phases. Therefore, it is possible to enhance the suppression of the self-surge voltage interference between the upper and lower arm circuits  10  through the electric power line. 
     Further, in the present example, the upper arm  10 U has the multiple main terminals  70 C connected to the upper wiring  11 Pa, and the lower arm  10 L has the multiple main terminals  70 E connected to the lower wiring  11 Na. Therefore, the self-surge voltages of the adjacent main terminals  70 C and  70 E act so as to cancel out each other, and it is possible to reduce the in-phase upper inductance L 1 P and the in-phase lower inductance L 1 N. As such, the suppression of the self-surge voltage is enhanced. 
     Further, in the present example, the output bus bar  150  (that is, output wiring  15 ) connecting the main terminals  70 E of the upper arm  10 U and the main terminals  70 C of the lower arm  10 L is provided. The output bus bar  150  has the facing portions  154   p  and  154   n  facing the upper wiring  11 Pa and the lower wiring  11 Na. Therefore, the self-surge voltages act so as to cancel out each other between the facing portions  154   p  and  154   n  of the output bus bar  150  and the upper wiring  11 Pa and the lower wiring  11 Na. Hence, it is possible to reduce the in-phase upper inductance L 1 P and the in-phase lower inductance L 1 N. As such, the suppression of the self-surge voltage is enhanced. 
     In the present example, particularly, in the configuration having the semiconductor devices  20  of the 1-in-1 package structure, the P bus bar  130  and the N bus bar  140  face the output bus bar  150  in the Y direction, as described above. In the projection view in the Y direction, the output bus bar  150  and the semiconductor devices  20  overlap each other. The facing portion  135   a  of the P bus bar  130  is arranged between the semiconductor chip  40 U and the output bus bar  150  in the Y direction. Similarly, the facing portion  145   a  of the N bus bar  140  is arranged between the semiconductor chip  40 L and the output bus bar  150  in the Y direction. As a result, the current path from the P bus bar  130  to the output bus bar  150  via the semiconductor chip  40 U and the current path from the output bus bar  150  to the N bus bar  140  via the semiconductor chip  40 L are formed as shown by the long dashed double-dotted line arrows in  FIG. 23 . Accordingly, it is possible to reduce the area of the current loop, as compared with a 2-in-1 package in which two semiconductor chips forming the upper and lower arm circuit  10  are formed in one package. As a result, the self-surge voltage can be further reduced. 
     Further, in the present example, the interphase upper impedance is larger than the in-phase upper impedance. The interphase lower impedance is larger than the in-phase lower impedance. Therefore, as shown by the arrows Y 2  in  FIG. 28 , it is possible to restrict the surge voltage from propagating over the closed loop circuit of each phase and interfering. 
     Further, in the present example, the smoothing capacitor C 2  is connected to the upper and lower arm circuit  10  in parallel, and smooths the voltage of the electric power line. According to this, the voltage fluctuation of the electric power line can be suppressed. Since the electric charges can be instantaneously supplied from the smoothing capacitor C 2  to the capacitor C 1 , the capacitance of the capacitor C 1  can be reduced. As such, it is possible to reduce the size of the capacitor C 1 . 
     The example in which the two semiconductor devices  20  each having the 1-in-1 package structure are used as the semiconductor devices  20  has been described. However, the present embodiment is not limited to the example described. A semiconductor device having a 2-in-1 package structure in which elements for the two arms (upper arm  10 U and lower arm  10 L) forming the upper and lower arm circuit  10  are packaged in a unit can be used. 
     The arrangement of the main terminals  70  is not limited to the example described above. In the case of the 1-in-1 package, the semiconductor device  20  may have at least one main terminal  70 C and at least one main terminal  70 E. The main terminal  70  having the same potential may be divided into multiple terminals. For example, the main terminal  70 C may be divided into multiple terminals. By parallelizing the multiple terminals, it is possible to reduce the entire inductance of the divided terminals. In the case of the 2-in-1 package, it is sufficient to have at least one main terminal  70 C of the upper arm  10 U, and at least one main terminal  70 E of the lower arm  10 L, and at least one output terminal. 
     In the example shown in  FIG. 27 , the common wiring portions  132  and  142  extend opposite to the parallel portions  134  and  144  with respect to the connection portions  131  and  141 . On the other hand, as shown in  FIG. 29 , the common wiring portions  132  and  142  may extend on the same side as the parallel portions  134  and  144  with respect to the connection portions  131  and  141 . The extending direction of the common wiring portions  132  and  142  may be differentiated between the upper arm  10 U and the lower arm  10 L. For example, the common wiring portions  132  and  142  may not be arranged so as to face each other. 
     In the example shown in  FIG. 27 , the upper arm  10 U and the lower arm  10 L have the multiple main terminals  70 C and  70 E. However, the upper arm  10 U and the lower arm  10 L may have at least one main terminal  70 C and one main terminal  70 E. In the example shown in  FIG. 27 , the main terminal  70 C and the main terminal  70 E are alternately arranged. Alternatively, the multiple main terminals  70 C may be arranged next to each other or the multiple main terminals  70 E may be arranged next to each other. 
     Contrary to the example shown in  FIG. 27 , the interphase upper impedance may be smaller than the in-phase upper impedance. The interphase lower impedance may be smaller than the in-phase lower impedance. 
     As another example of the power module  110 , at least one of the cooling unit  120 , the drive substrate  160 , and the protective member  180  may be deleted from the power module  110 . The electric power conversion device  5  may not have the smoothing capacitor C 2 . The capacitor C 1  may be arranged outside the protective member  180 . The structure of the cooling unit  120  may not be limited to the example described above. A part of the semiconductor device  20  forming the upper and lower arm circuit  10  may be inserted into the flow path  126  of the cooling unit  120  to be immersed in the refrigerant. In such a configuration, the capacitor C 1  may be placed on the cooling unit  120  to be connected to the semiconductor device  20 . In the case where the capacitor C 1  is immersed in the refrigerant, it is possible to suppress the surge voltage while cooling the semiconductor device  20  from both sides. 
     (Motor Generator) 
     As shown in  FIG. 30 , the motor generator  3  has an annular stator  701 , a rotor  702  provided inside the stator  701 , and a housing  703  accommodating the stator  701  and the rotor  702  therein. The motor generator  3  corresponds to a rotary electric machine. In the present embodiment, the rotor  702  rotates about the center line CL 2  of the rotor  702 , and a direction in which the center line CL 2  extends is referred to as an axial direction α. In this case, a radial direction β of the stator  701  and a circumferential direction γ of the stator  701  are both orthogonal to the axial direction α. In  FIG. 31 , a virtual point VP on the center line CL 2  is assumed. At the virtual point VP, the axial direction α, the radial direction β, and the circumferential direction γ are orthogonal to each other. 
     As shown in  FIG. 30 , the stator  701  is fixed to the housing  703 , and the outer peripheral surface of the stator  701  faces the housing  703 . The stator  701  includes an annular stator core  705  and a stator winding  706  wound around the stator core  705 . The stator core  705  is formed by a plurality of annular electromagnetic steel sheets stacked in the axial direction α, so that the stator core  705  has a tubular shape as a whole. The stator winding  706  includes a plurality of conductor segments. The stator winding  706  is formed by connecting these conductor segments to each other in a state of being mounted on the stator core  705 . The conductor segment includes a long conductor and an insulating coating covering the outer peripheral surface of the conductor. The insulating film is formed of a resin material such as a polyimide resin. The stator core  705  is provided with a plurality of slots penetrating in the stator core  705  in the axial direction α. The conductor segments are inserted into the slots, thereby to form the stator core  705 . 
     The rotor  702  has a rotor hole  702   a  that is coaxial with the rotor  702  and extends along the center line CL 2 . Thus, the rotor  702  has an annular shape due to the rotor hole  702   a . The rotor  702  includes a plurality of permanent magnets, and the outer peripheral surface of the rotor  702  is formed by these permanent magnets. In the rotor  702 , the plurality of permanent magnets form a plurality of magnetic poles having alternately different polarities in the circumferential direction γ. The outer peripheral surface of the rotor  702  is separated from the inner peripheral surface of the stator  701  in a radially inward direction. 
     The motor generator  3  includes a motor shaft portion  708  fixed to the rotor  702  and bearing portions  709  that rotatably supports the motor shaft portion  708 . The center line of the motor shaft portion  708  coincides with the center line CL 2  of the rotor  702 , and the motor shaft portion  708  rotates together with the rotor  702 . The motor shaft portion  708  extends from the rotor  702  in the axial direction α. The motor shaft portion  708  is fixed to the rotor  702  in a state of being inserted in the rotor hole  702   a . The motor shaft portion  708  is a long tubular member, and has a motor shaft hole  708   a  coaxial with the motor shaft portion  708  and extending along the center line CL 2 . The bearing portions  709  are fixed to the housing  703 . Two bearing portions  709  are provided so as to be spaced apart from each other in the axial direction α. 
     As shown in  FIG. 30  and  FIG. 31 , the housing  703  has a housing flow path  711  through which a refrigerant flows. In the housing  703 , the housing flow path  711  is provided between the inner peripheral surface and the outer peripheral surface arranged in the radial direction β. The housing flow path  711  extends in the radial direction β and the circumferential direction γ. The housing flow path  711  extends along the outer peripheral surface of the stator  701 , and is circular while going around in the circumferential direction γ. In the axial direction α, the length dimension of the housing flow path  711  is larger than the length dimension of the stator  701 , and both ends of the housing flow path  711  project outward from the stator  701 . Note that in  FIG. 31 , components such as the stator  701  and the rotor  702  accommodated in the housing  703  are not shown. 
     The housing  703  has an inner cooling part  712  provided inside the housing flow path  711  in the radial direction and an outer cooling part  713  provided on the outer side of the housing flow path  711  in the radial direction. The housing  703  is made of a metal material. In particular, at least the inner cooling part  712  and the outer cooling part  713  are made of a material having thermal conductivity. The inner cooling part  712  forms at least a part of the inner peripheral surface of the housing  703 , and the outer cooling part  713  forms at least a part of the outer peripheral surface of the housing  703 . The inner cooling part  712  and the outer cooling part  713  extend in the axial direction α and the circumferential direction γ along the housing flow path  711 , and each forms an annular shape by circulating in the circumferential direction γ. The inner cooling part  712  covers the entire housing flow path  711  on the radially inner side of the housing flow path  711 , and the outer cooling part  713  covers the entire housing flow path  711  on the radially outer side. The inner cooling part  712  corresponds to a first cooling part and a housing cooling part, and the outer cooling part  713  corresponds to a second cooling part. 
     The housing  703  has an inner peripheral part that forms an inner peripheral surface of the housing  703  and an outer peripheral part that forms an outer peripheral surface of the housing  703 . The inner cooling part  712  is included in the inner peripheral part and forms at least a portion of the inner peripheral part. The outer cooling part  713  is included in the outer peripheral part and forms at least a portion of the outer peripheral part. 
     The housing  703  has an inflow hole  715  (see  FIG. 34 ) for allowing the refrigerant to flow into the housing flow path  711  and an outflow hole  716  (see  FIG. 34 ) for allowing the refrigerant to flow out from the housing flow path  711 . The inflow hole  715  and the outflow hole  716  are through holes that penetrate the outer cooling part  713  in the radial direction β. The housing  703  is provided with an inflow pipe  717  that allows the refrigerant to flow into the inflow hole  715  and an outflow pipe  718  that allow the refrigerant to flow out from the outflow hole  716 . The inflow pipe  717  and the outflow pipe  718  extend radially outward from the housing  703 , and can connect to the refrigerant pipe through which the refrigerant flows. 
     A vehicle is equipped with a cooling circuit that cools the refrigerant flowing through the housing flow path  711 . The cooling circuit includes a heat exchanger, such as a radiator, that cools the refrigerant by heat exchange with air or the like, a circulation pump that circulates the refrigerant, and a refrigerant pipe that circulates the refrigerant. In the cooling circuit, the housing flow path  711  is connected in series with the heat exchanger, and the refrigerant cooled by the heat exchanger flows into the housing flow path  711 . The refrigerant pipe of the cooling circuit is connected to the inflow pipe  717  and the outflow pipe  718 . 
     In the housing  703 , when the refrigerant cooled by the cooling circuit flows into the housing flow path  711 , the internal cooling part  712  and the external cooling part  713  are cooled by the refrigerant. Then, heat exchange is performed between the inner cooling part  712  and the stator  701 , and hence the stator  701  is cooled. 
     (Electric Power Conversion Device) 
     The electric power conversion device  5  is attached to the motor generator  3 . A unit in which the electric power conversion device  5  and the motor generator  3  are assembled and integrated with each other is referred to as an electromechanical integrated-type motor unit  800 . As shown in  FIG. 32 , the motor unit  800  has a speed reducer  810  and a differential gear  820 . The speed reducers  810  and the differential gear  820  are attached to the motor generator  3  in the similar manner to the electric power conversion device  5 . The speed reducer  810  and the differential gear  820  will be described later. The motor unit  800  corresponds to a rotary electric machine unit. 
     In the present embodiment, the electric power conversion device  5  does not have a storage case for accommodating components such as the power modules  110  and the smoothing capacitor C 2 . That is, the electric power conversion device  5  is not packaged into one package. Therefore, the components of the electric power conversion device  5  are individually attached to the housing  703 . 
     As described above, the motor generator  3  is a three-phase rotary electric machine, and the power conversion device  5  has the power modules  110  correspondingly for the respective phases such as the U-phase, V-phase, and W-phase. The electric power conversion device  5  includes multiple smoothing capacitors C 2 . In this embodiment, the electric power conversion device  5  has three power modules  110  and three smoothing capacitors C 2 . 
     As shown in  FIG. 33 , the power modules  110  and the smoothing capacitors C 2  are individually attached to the outer peripheral surface of the housing  703 . The three power modules  110  are arranged in the circumferential direction γ. Each of the three power modules  110  extends in the tangential direction orthogonal to the radial direction β and extends in the axial direction α. The three power modules  110  are not arranged evenly in the circumferential direction γ, but the two power modules  110  at both ends are arranged adjacent to the middle power module  110  in the circumferential direction γ. For example, assuming a cross-section of the housing  703  taken in a direction orthogonal to the center line CL 2 , the three power modules  110  are included in a range of a central angle of 180 degrees. 
     Similarly to the three power modules  110 , the three smoothing capacitors C 2  are also arranged in the circumferential direction. The power module  110  and the smoothing capacitor C 2  are arranged one by one in the axial direction α, and both extend in the tangential direction orthogonal to the radial direction β and extend in the axial direction α. In this case, there are three sets of the power module  110  and the smoothing capacitor C 2  arranged in the axial direction α. In each set, the power module  110  is located between one end of the housing  703  and the smoothing capacitor C 2 . That is, in each set, the arrangement order of the power module  110  and the smoothing capacitor C 2  in the axial direction α is the same. 
     The housing  703  has an installation surface  713   a  on the outer cooling part  713 . The installation surface  713   a  is a part of the outer peripheral surface formed by the outer cooling part  713 , and extends in the tangential direction orthogonal to the radial direction β and the axial direction α. Three installation surfaces  713   a  are arranged in the circumferential direction γ, and one set of the power module  110  and the smoothing capacitor C 2  is installed on one installation surface  713   a.    
     As shown in  FIGS. 31 and 33 , the outer cooling part  713  is provided with installation recesses  713   b  each recessed in a radially inward direction. The bottom surface of the installation recess  713   b  is the installation surface  713   a , and the power module  110  and the smoothing capacitor C 2  are received in the installation recess  713   b . Three installation recesses  713   b  are arranged in the circumferential direction γ, and one set of the power module  110  and the smoothing capacitor C 2  is received in one installation recess  713   b . In the radial direction β, the depth dimension of the installation recess  713   b  is larger than both the thickness dimension of the power module  110  and the thickness dimension of the smoothing capacitor C 2 . The installation recess  713   b  has an inner wall surface  713   c  extending radially outward from the installation surface  713   a . The inner wall surface  713   c  surrounds the power module  110  and the smoothing capacitor C 2  from all sides. The inner wall surface  713   c  is spaced apart from the power module  110  and the smoothing capacitor C 2  in the axial direction α and the circumferential direction γ. 
     An installation cover  721  is attached to the housing  703  for covering the installation recess  713   b  from the outside in the radial direction. The power module  110  and the smoothing capacitor C 2  received in the installation recess  713   b  are protected by the installation cover  721 . The outer surface of the installation cover  721  is provided with ribs that protrude outward in the radial direction. These ribs enhance the heat dissipation performance and strength of the installation cover  721 . Note that, in  FIG. 33 , the installation cover  721  is not shown. 
     The electric power conversion device  5  has the control substrate  290  on which the control circuit  9  is formed, and a signal connector  291  mounted on the control substrate  290 . The control substrate  290  is formed by mounting an electronic component on a printed board. The control substrate  290  includes a microcomputer as the electronic component. The control substrate  290  is attached to the housing  703  in the similar manner to the power module  110  and the smoothing capacitor C 2 . 
     The housing  703  has a substrate accommodating portion  722  accommodating the control substrate  290 . The substrate accommodating portion  722  is provided at the end of the housing  703 , the end being adjacent to the power module  110  than the smoothing capacitor C 2  in the axial direction α. The substrate accommodating portion  722  is provided by a portion protruding from the end surface of the housing  703  in the axial direction α. The substrate accommodating portion  722  provides an internal space opening therein in the axial direction α. The control substrate  290  is installed in the internal space of the board accommodating portion  722  in a direction in which the plate surface is orthogonal to the axial direction α. A substrate cover  723  is attached to the housing  703  to cover the opening of the substrate accommodating portion  722 . The control substrate  290  is protected by the substrate cover  723 . 
     The signal connector  291  is attached to the housing  703  in a state of protruding outward in the radial direction from the substrate accommodating portion  722 . The signal connector  291  can be connected to a connector of an in-vehicle device, such as an upper ECU. When the signal connector  291  and the connector of the in-vehicle device are connected to each other, signals can be exchanged between the in-vehicle device and the control circuit  9 . The signal connector  291  has a connection port to receive the connector of the in-vehicle device, and the connection port faces outward in the radial direction. The connection port of the signal connector  291  may face in the axial direction α or in the radial direction β. For example, the connection port may face in a direction opposite to the installation recess  713   b  in the axial direction α, or may face toward the inflow pipe  717  in the circumferential direction γ. The shape, installation position, and direction of the connection port of the signal connector  291  are preferably set so that the size of the housing  703  is as small as possible in the radial direction β. In this case, the housing  703  can be reduced in size in the radial direction β. 
     The power module  110  is installed on the installation surface  713   a  so that the output bus bar  150  extends toward the substrate accommodating portion  722  in the axial direction α. The housing  703  is formed with a communication hole for allowing communication between the internal space of the installation recess  713   b  and the internal space of the substrate accommodating portion  722 , and the output bus bar  150  of the power module  110  is inserted into the communication hole. The output bus bar  150 , which is the output wiring  15 , is connected to the stator winding  706  of the motor generator  3  in the substrate accommodating portion  722 . The output bus bar  150  reaches the internal space of the substrate accommodating portion  722  by projecting outward from the stator  701  in the axial direction α. The length dimension of the output bus bar  150  in the axial direction α is the same between the respective power modules  110 . The connection portion between the output bus bar  150  and the stator winding  706  is covered with the control substrate  290  or the substrate cover  723 . The output bus bar  150  corresponds to an output wiring. 
     The electric power conversion device  5  has an input terminal block  240  to which the connector of the DC power supply  2  is connected. The input terminal block  240  is provided at an end portion of the housing  703  opposite to the substrate accommodating portion  722 . The input terminal block  240  has a positive electrode terminal and a negative electrode terminal for electrically connecting the DC power supply  2  and the electric power conversion device  5 , and a housing for housing the positive electrode terminal and the negative electrode terminal. The positive electrode terminal and the negative electrode terminal function as, for example, terminals for inputting the DC voltage supplied from the DC power supply  2  to the electric power conversion device  5 . Each of the positive electrode terminal and the negative electrode terminal may be formed of one conductive member (for example, bus bar), or may be formed of multiple conductive members electrically connected. 
     The input terminal block  240  has a connection port to which the connector of the DC power supply  2  can be connected. The connection port faces in the circumferential direction γ. The connection port faces in the circumferential direction γ and in a direction close to the inflow pipe  717 , for example. The connection port of the input terminal block  240  may face in the axial direction α or in the radial direction β. The shape, installation position, and orientation of the installation port of the input terminal block  240  are preferably set so that the size of the housing  703  is as small as possible in the radial direction β. In this case, the housing  703  can be reduced in size in the radial direction β. 
     The electric power conversion device  5  has N bus bars  282  constituting the above-described N line  13  and VH bus bars  284  constituting the above-described VH line  12 H. These bus bars  282  and  284  are each formed by processing, for example, pressing a metal plate material having an excellent conductivity such as copper. The N bus bars  282  and the VH bus bars  284  are electrically connected to the power modules  110  and the smoothing capacitors C 2 . The N bus bar  282  and the VH bus bar  284  are provided on the outer peripheral side of the housing  703  to extend in the axial direction α. The N bus bar  282  and the VH bus bar  284  extend from the smoothing capacitor C 2  toward the input terminal block  240  in the axial direction α, and are electrically connected to the input terminal block  240 . 
     (Cooling of Motor Unit) 
     Next, the cooling structure of the motor unit  800  will be described with reference to  FIGS. 31, 34, and 35 . Note that  FIG. 34  shows a cross-sectional view of the annular housing  703  taken in the circumferential direction γ and in parallel with the center line CL 2 , assuming a state in which the annular housing  703  is extended so that the circumferential direction γ corresponds to the horizontal axis. In  FIG. 35 , for convenience, the power module  110  has one semiconductor device  20 . 
     As shown in  FIGS. 31, 34, and 35 , the refrigerant flowing through the housing flow path  711  can pass through the cooling unit  120  of the power module  110 . In the cooling unit  120 , an upstream end portion and a downstream end portion of the flow path  126  are both connected to the housing flow path  711 . The housing  703  has a supply hole  731  for supplying the refrigerant from the housing flow path  711  to the power module  110 , and a discharge hole  732  for discharging the refrigerant from the power module  110  to the housing flow path  711 . The supply hole  731  and the discharge hole  732  are both provided in the outer cooling part  713 . The supply hole  731  and the discharge hole  732  are through holes that penetrate the outer cooling part  713  in the radial direction β. One set of the supply hole  731  and the discharge hole  732  is provided for each power module  110 . 
     The supply pipe  121  of the cooling unit  120  is inserted into the supply hole  731 , and the supply pipe  121  and the outer cooling part  713  are connected to each other. The discharge pipe  122  of the cooling unit  120  is inserted into the discharge hole  732 , and the discharge pipe  122  and the outer cooling part  713  are connected to each other. The connection portion between the supply pipe  121  and the outer cooling part  713 , and the connection portion between the discharge pipe  122  and the outer cooling part  713  are each fluid-tightly sealed by an annular elastic member such as an O-ring or a sealing member that is in a liquid state before being cured, by welding or the like. 
     As shown in  FIG. 34 , the housing flow path  711  has an inflow region  741  in communication with the inflow hole  715  and an outflow region  742  in communication with the outflow hole  716 . In the housing  703 , the inflow region  741  and the outflow region  742  are separated from each other. The inflow region  741  and the outflow region  742  are communicated with each other through the flow paths  126  of the power modules  110 . In the housing flow path  711 , all the supply holes  731  are in communication with the inflow region  741 , and all the discharge holes  732  are in communication with the outflow region  742 . The housing  703  has partition portions  743  and  744  that partition the housing flow path  711  into the inflow region  741  and the outflow region  742 . 
     Of the partition portions  743  and  744 , the first partition portion  743  is provided between the inflow hole  715  and the outflow hole  716 . The inflow hole  715  and the outflow hole  716  are arranged in the axial direction α in the outer cooling part  713 , and the first partition portion  743  is provided between the inflow hole  715  and the outflow hole  716 . In this configuration, the refrigerant that has flowed into the housing flow path  711  from the inflow hole  715  flows around the housing  703  one turn in the circumferential direction γ, and then flows out from the outflow hole  716 . Therefore, the entirety of the outer peripheral surface of the stator  701  is easily cooled by the refrigerant flowing through the housing flow path  711 . In  FIG. 34 , the first partition portion  743  is shown to extend straight in the axial direction α. However, in reality, the first partition portion  743  also has a portion inclined with respect to the axial direction α. 
     Of the partition portions  743  and  744 , the second partition portion  744  is provided between the supply holes  731  and the discharge holes  732 . In the set of the supply hole  731  and the discharge hole  732 , the supply hole  731  and the discharge hole  732  are at least separated from each other in the axial direction α. The supply holes  731  of the respective sets and the discharge holes  732  of the respective sets are arranged parallel to each other in the circumferential direction γ. The second partition portion  744  has a peripheral wall portion  744   a  extending in the circumferential direction γ and an axial wall portion  744   b  extending in the axial direction. The peripheral wall portion  744   a  is provided between each supply hole  731  and each discharge hole  732 . The peripheral wall portion  744   a  is provided at a position close to one of ends of the housing  703 , the one being adjacent to the substrate accommodating portion  722  in the axial direction α. In the housing flow path  711  in which the thickness dimension in the radial direction β is uniform, the volume of the inflow region  741  is smaller than the volume of the outflow region  742 . 
     The inflow region  741  and the outflow region  742  both extend in the circumferential direction γ. The plurality of power modules  110  are arranged in the circumferential direction γ in the order of the power module  110  of the U phase, the power module  110  of the V phase, and the power module  110  of the W phase of the inverter  7  as a function of distance from the inflow hole  715 . 
     The power module  110  is provided upstream of the smoothing capacitor C 2  with respect to the housing flow path  711 . A portion of the housing flow path  711  facing the power module  110  in the radial direction β is arranged upstream of a portion of the housing flow path  711  facing the smoothing capacitor C 2  in the radial direction β. The portion facing the power module  110  includes a portion of the inflow region  741  and a portion of the outflow region  742 , and the portion facing the smoothing capacitor C 2  includes a portion of the outflow region  742 . A portion of the outflow region  742  facing the power module  110  is arranged upstream of a portion of the outflow region  742  facing the smoothing capacitor C 2  because the portion of the outflow region  742  facing the power module  110  is arranged at a position closer to the discharge hole  732  than the portion facing the smoothing capacitor C 2 . The inflow region  741  and the outflow region  742  correspond to the portion to which the power modules  110  face, and the outflow region  742  corresponds to the portion to which the smoothing capacitors C 2  face. 
     In the present embodiment, the power module  110  has the cooling unit  120 . The power module  110  has a structure shown in  FIG. 22 . That is, in the power module  110 , the capacitor C 1 , the heat exchange part  123  of the first stage, the semiconductor device  20 , the heat exchange part  123  of the second stage, the drive substrate  160  are arranged in this order in the direction away from the one surface  181  of the protective member  180 . 
     As shown in  FIG. 35 , the semiconductor device  20  has one surface  20   a  and a rear surface  20   b  opposite to the one surface  20   a  in the thickness direction of the semiconductor device  20 . In the power module  110 , the housing flow path  711  is provided on a side adjacent to the one surface  20   a  of the semiconductor device  20 , and the flow path  126  extends along the rear surface  20   b . In this case, the one surface  20   a  of the semiconductor device  20  and the outer cooling part  713  of the housing  703  opposed with each other with the capacitor C 1  and the like interposed therebetween, and the rear surface  20   b  of the semiconductor device  20  and the one surface of the heat exchange part  123  of the second stage face each other. Further, one surface of the capacitor C 1  and the outer cooling part  713  of the housing  703  face each other. The rear surface of the capacitor C 1  opposite to the one surface facing the outer cooling part  713  of the housing  703  faces the one surface of the heat exchange part  123  of the first stage in the thickness direction. 
     In regard to the power module  110 , the cooling unit  120  corresponds to a module cooling unit, and the flow path  126  corresponds to a module flow path. Further, the one surface  181  of the protective member  180  corresponds to one surface of the power module  110 , and the rear surface  182  of the protective member  180  corresponds to a rear surface of the power module  110 . 
     In the housing flow path  711 , the inflow region  741  and the outflow region  742  communicate with each other via the flow path  126  of the power module  110 . The inflow region  741 , the flow path  126 , and the outflow region  742  form one flow path. Therefore, the same refrigerant flows through the flow paths  126  and  711 . 
     In the structure described above, the refrigerant flows as described below. In the housing  703 , the refrigerant supplied from the inflow hole  715  into the inflow region  741  of the housing flow path  711  flows through the inflow region  741  toward the supply hole  731 , as shown in  FIG. 34 . Then, the refrigerant flows from the inflow region  741  to the outflow region  742  through the flow path  126  of the power module  110 . 
     Specifically, the refrigerant flows from the inflow region  741  to each of the heat exchange parts  123  of the two stages through the supply pipe  121 , and is discharged from the discharge pipe  122  to the outflow region  742 . As described above, the supply pipe  121  and the discharge pipe  122  are provided at the diagonal positions with respect to the heat exchange parts  123  having substantially the rectangular planar shape. Further, the supply pipe  121  is located closer to the inflow hole  715  in the circumferential direction γ than the discharge pipe  122 . Therefore, the refrigerant flows through the flow paths  126  in the heat exchange parts  123  as shown by the broken line arrows in  FIGS. 34 and 35 . 
     The refrigerant that has flowed from the flow paths  126  into the outflow region  742  flows toward the outflow hole  716  while flowing along the smoothing capacitor C 2  arranged adjacent to the outer cooling part  713  and along the stator  701  arranged adjacent to the inner cooling part  712 , and then flows out from the outflow hole  716 . In this case, the refrigerant cools the smoothing capacitor C 2  by exchanging heat with the outer cooling part  713  of the housing  703 , and cools the stator  701  by exchanging heat with the inner cooling part  712 . 
     (Speed Reducer, Differential Gear) 
     As shown in  FIG. 30 , the motor unit  800  includes a unit case  830  accommodating a speed reducer  810  and a differential gear  820 , and transmission shaft portions  840   a  and  840   b  for transmitting a driving force to left and right wheels. The unit case  830  is provided next to the motor generator  3  in the axial direction α, and is attached to the motor generator  3 . In the motor unit  800 , the motor generator  3 , the speed reducer  810 , and the differential gear  820  are aligned in the axial direction α. The center line of the speed reducer  810  and the center line of the differential gear  820  both coincide with the center line CL 2  of the rotor  702 . 
     The speed reducer  810  is a device that reduces the rotation speed of the motor generator  3  and outputs the rotation. The speed reducer  810  includes a sun gear  811 , a compound planetary gear  812 , a fixed gear  813 , and a planet carrier  814 . The sun gear  811  has a plurality of external teeth extending outward in the radial direction. The sun gear  811  is coaxial with the motor shaft portion  708  of the motor generator  3  and is fixed to the motor shaft portion  708 . The sun gear  811  rotates together with the motor shaft portion  708 . The sun gear  811  has a sun gear hole  811 a coaxial with the sun gear  811  and extending along the center line CL 2 . The fixed gear  813  has a plurality of internal teeth extending inward in the radial direction, and is fixed to the unit case  830 . 
     The compound planetary gear  812  has a first gear  812   a  that meshes with the sun gear  811  and a second gear  812   b  that meshes with the fixed gear  813 . The first gear  812   a  and the second gear  812   b  both have a plurality of external teeth extending outward in the radial direction. The first gear  812   a  and the second gear  812   b  are fixed to each other in a state of being coaxially arranged in the axial direction α, and the second gear  812   b  rotates together with the first gear  812   a . The first gear  812   a  is a large-diameter gear having a larger diameter than the second gear  812   b , and the second gear  812   b  is a small-diameter gear. 
     A planetary shaft portion  812   c , which is coaxial with the first gear  812   a  and the second gear  812   b , is rotatably fixed to the planet carrier  814 . The planetary shaft portion  812   c  rotates with the rotation of the planet carrier  814 , and moves in the circumferential direction γ with the rotation of the sun gear  811 . The number of times the planetary shaft portion  812   c  rotates around the center line CL 2  is a value reduced by a predetermined ratio with respect to the rotation speed of the motor shaft portion  708 . In the present embodiment, the speed reducer  810  is configured to reduce the rotation speed of the motor shaft portion  708  to output the rotation reduced in speed. Alternatively, the speed reducer  810  may be a speed increaser configured to increase the rotation speed of the motor shaft portion  708  to output the rotation increased in speed. 
     The differential gear  820  is a differential device that outputs power according to the difference in rotational resistance when the rotational resistance of the wheel is different between the left wheel and the right wheel, and connects the left and right transmission shaft portions  840   a  and  840   b . The differential gear  820  has a differential case  821 , a pinion gear  822 , and side gears  823   a  and  823   b . The differential case  821  is attached to the planet carrier  814 . The pinion gear  822  is rotatably attached to the differential case  821  with its rotation axis orthogonal to the center line CL 2 , and moves in the circumferential direction γ together with the differential case  821 . 
     The side gears  823   a  and  823   b  each have a rotation axis orthogonal to the rotation axis of the pinion gear  822 , and are arranged coaxially with each other. The side gears  823   a  and  823   b  are coaxially arranged on the motor shaft portion  708  and mesh with the pinion gear  822 . Of the side gears  823   a  and  823   b , the first transmission shaft portion  840   a  is coaxially fixed to the first side gear  823   a , and the second transmission shaft portion  840   b  is coaxially fixed to the second side gear  823   b . In the differential gear  820 , when the differential case  821  is rotating and the pinion gear  822  is not rotating, the first side gear  823   a  and the second side gear  823   b  rotate at the same speed. On the other hand, when the pinion gear  822  rotates, the first side gear  823   a  and the second side gear  823   b  rotate at different speeds. 
     The first side gear  823   a  is provided on the side opposite to the motor generator  3  with the second side gear  823   b  interposed therebetween in the axial direction α. The first transmission shaft portion  840   a  extends from the first side gear  823   a  in the axial direction α toward the side opposite to the motor generator  3 . The second transmission shaft portion  840   b  extends in the axial direction α from the second side gear  823   b  toward the motor generator  3 . The second transmission shaft portion  840   b  penetrates the motor generator  3 , the speed reducer  810 , and the unit case  830 , and extends to the side opposite to the first transmission shaft portion  840   a  with the motor generator  3  interposed therebetween. The second transmission shaft portion  840   b  is inserted into the motor shaft portion hole  708   a  and the sun gear hole  811   a , and is rotatable inside these holes  708   a  and  811   a.    
     Bearings  831  and  832  that rotatably support the first transmission shaft portion  840   a  are attached to the unit case  830 . The bearing portions  831 ,  832  are provided so as to be separated from each other in the axial direction α. For example, the bearing portion  831  is provided at the end of the unit case  830  adjacent to the first transmission shaft portion  840   a , and the bearing portion  832  is provided at the end of the unit case  830  adjacent to the second transmission shaft portion  840   b.    
     The speed reducer  810  may have a plurality of rollers that rotate due to friction between the contact surfaces of the gears, in place of or in addition to the plurality of gears that rotate with the teeth meshed with each other. For example, the speed reducer has a sun roller having the function of the sun gear  811 , a fixed roller having the function of the fixed gear  813 , and a composite planet roller having the function of the composite planetary gear  812 . In this configuration, for the purpose of improving the friction effect, the contact surfaces of each of the pair of fixed rollers arranged coaxially with the planetary rollers may be tilted by a predetermined angle with respect to the rotation axis of the planetary rollers, to thereby increase the contact area between the fixed roller and the planetary roller. Further, in a speed reducer in which a planetary roller is interposed between a pair of fixed rollers arranged coaxially, an elastic member that presses the planetary roller toward at least one of the pair of fixed rollers may be provided. 
     (Effects of Motor Unit) 
     Next, effects of the motor unit  800  of the present embodiment will be described. 
     According to the present embodiment, since the inner cooling part  712  of the housing  703  extends along the outer peripheral surface of the stator  701 , the stator  701  can be cooled in a wide range by the inner cooling part  712 . Therefore, it is possible to suppress the occurrence of abnormalities in the stator  701 , such as deterioration of the coating of the stator winding  706  due to high temperature. Further, since the plurality of power modules  110  are individually attached to the housing  703  along the outer cooling part  713 , each power module  110  can be arranged at a position as close as possible to the housing flow path  711 . That is, each power module  110  can be individually installed at a position and in an orientation such that the cooling effect of the outer cooling part  713  is high. Therefore, the cooling effect can be enhanced for both the motor generator  3  and the electric power conversion device  5 . 
     Moreover, since the plurality of power modules  110  are arranged in the circumferential direction γ, each power module  110  can be arranged adjacent to the one end the housing  703  in the axial direction α. Therefore, when the power module  110  and the stator winding  706  are connected by the board accommodating portion  722  at one end of the housing  703 , each power module  110  can be arranged at a position as close as possible to the substrate accommodating portion  722 . In this case, since the output bus bar extending from the power module  110  can be shortened as much as possible, the heat generated by the output bus bar  150  can be reduced. As described above, since the heat generated in the motor unit  800  is reduced, the cooling effect in the motor unit  800  can be further enhanced. 
     In a configuration in which a plurality of power modules  110  are individually attached to the housing  703 , there is a concern that the configuration for electrically connecting the power module  110  and the stator  701  is complicated. On the other hand, according to the present embodiment, since the power modules  110  are arranged in the circumferential direction γ, the output bus bars  150  extending from the power modules  110  are extended straight in the axial direction α toward the substrate accommodating portion  722 . Therefore, it is not necessary to arrange the output bus bar  150  extending from one power module  110  so as to avoid the other power modules  110 . As such, the shape of the output bus bars  150  can be simplified and the installation work of the output bus bars  150  can be facilitated. 
     Further, the plurality of power modules  110  are arranged in the circumferential direction γ and fixed to the housing  703 . Therefore, the motor unit  800  can be reduced in size in the radial direction β, as compared with a configuration in which the power modules  110  are arranged, for example, in the radial direction  13  and fixed to the housing  703 . In addition, the smoothing capacitor C 2  and the power module  110  are arranged along the outer peripheral surface of the housing  703 . Therefore, for example, the motor unit  800  can be reduced in size in the radial direction β, as compared with a configuration in which the smoothing capacitor C 2  and the power module  110  are arranged in the radial direction β. Moreover, since the plurality of smoothing capacitors C 2  are arranged along the outer peripheral surface of the housing  703 , the motor unit  800  can be reduced in size in the radial direction β, as compared with a configuration in which a plurality of smoothing capacitors C 2  are arranged, for example, in the radial direction β. 
     According to the present embodiment, the output bus bar  150  of the power module  110  extends in the axial direction α and toward the one end of the housing  703 . In this configuration, it is possible to easily realize a configuration of arranging the connecting portion electrically connecting the output bus bar  150  and the stator winding  706  at a position outside of the stator  701  in the axial direction α. Therefore, the work load when connecting the output bus bar  150  and the stator winding  706  can be reduced. 
     According to the present embodiment, the output bus bar  150  extends toward the one of ends of the housing  703 , the one being adjacent to the power modules  110  than the other. In this configuration, the length dimension of the output bus bar  150  can be shortened as much as possible. Therefore, it is possible to shorten the output bus bar  150 , to facilitate the work of attaching the output bus bar  150  to the housing  703 , to reduce the heat generated due to the power loss of the output bus bar  150 , and the like. 
     According to the present embodiment, the smoothing capacitor C 2  is attached to the housing  703  in a state of being arranged side by side with the power module  110  in the axial direction α, and the outer cooling part  713  of the housing  703  cools the smoothing capacitor C 2  by the refrigerant flowing through the housing flow path  711 . In this configuration, since the power module  110  and the smoothing capacitor C 2  are both cooled by the outer cooling part  713 , the cooling effect of the motor unit  800  can be enhanced. Moreover, since the smoothing capacitor C 2  is arranged next to the power module  110  in the axial direction α, the power module  110  can be arranged between the connection terminal of the stator  701  and the smoothing capacitor C 2 . Therefore, in addition to the simplification of the configuration for electrically connecting the power module  110  and the stator  701 , the configuration for electrically connecting the power module  110  and the smoothing capacitor C 2  can be simplified. 
     According to the present embodiment, the plurality of smoothing capacitors C 2  are arranged in the circumferential direction γ, similarly to the plurality of power modules  110 . In this configuration, in one set of the power module  110  and the smoothing capacitor C 2 , since the power module  110  and the smoothing capacitor C 2  can be arranged at positions as close as possible, the electrical wiring connecting the power module  110  and the smoothing capacitor C 2  can be shortened. In addition, the heat generated due to the power loss in the electric wiring can be reduced. 
     According to the present embodiment, the plurality of smoothing capacitors C 2  are arranged along the outer cooling part  713 . In this configuration, the separation distance between the smoothing capacitor C 2  and the housing flow path  711  can be made as small as possible. That is, the smoothing condensers C 2  can be individually installed at positions and in orientations such that the cooling effect by the outer cooling part  713  is enhanced. Therefore, the cooling effect of the smoothing capacitors C 2  by the outer cooling part  713  can be enhanced. 
     According to the present embodiment, the portion of the housing flow path  711  facing the power module  110  is located upstream of the portion of the housing flow path  711  facing the smoothing capacitor C 2 . In this configuration, the refrigerant cooled by the cooling circuit flows into the housing flow path  711  through the inflow hole  715  and then approaches the power module  110  before the smoothing capacitor C 2 . In this case, since the power module  110  is cooled by the refrigerant before the refrigerant receiving heat from the smoothing capacitor C 2  in the housing flow path  711 , the cooling effect of the power module  110  by the refrigerant can be enhanced. 
     According to the present embodiment, the inflow region  741  and the outflow region  742  are connected through the flow paths  126  of the respective power modules  110 . Therefore, it is possible to realize a configuration in which the refrigerant easily flows from the housing flow path  711  into the flow paths  126  of the power modules  110 . 
     According to the present embodiment, the flow paths  126  of the respective power modules  110  are in parallel with each other. In this configuration, the inflow region  741  and the outflow region  742  are connected by each of the three flow paths  126  of the three power modules  110 , each power module  110  having one flow path  126 . Therefore, the amount of refrigerant flowing from the inflow region  741  into the outflow region  742  is increased, as compared with a configuration in which the inflow region  741  and the outflow region  742  are connected through only one flow path  126 . Further, since the pressure loss in each flow path  126  is also reduced, it is possible to easily increase the amount of refrigerant flowing through one flow path  126 . Therefore, even if the flow rate of the refrigerant flowing through the flow path  126  of the power module  110  is smaller than that of the housing flow path  711 , the amount of the refrigerant flowing from the inflow region  741  into the outflow region  742  through the flow paths  126  of the respective power modules  110  into the outflow region  742  can be increased as much as possible. In this case, since the amount of the refrigerant circulating in the cooling circuit per unit time is unlikely to be insufficient, the cooling effect achieved by the refrigerant flowing in the housing flow path  711  and the flow paths  126  can be enhanced. 
     According to the present embodiment, the power module  110  is attached to the outer peripheral surface of the housing  703 , and the outer cooling part  713  forms at least a part of the outer peripheral surface of the housing  703 . In this configuration, the power modules  110  can be cooled by the outer cooling part  713 , which can realize the simplification of the structure for fixing the power modules  110  to the housing  703  and can facilitate the mounting work of the power modules  110 . 
     According to the present embodiment, the power module  110  is installed inside the installation recess  713   b . In the installation recess  713   b , the installation surface  713   a  and the inner wall surface  713   c  are both cooled by the refrigerant flowing through the housing flow path  711 . In this case, the installation surface  713   a  can cool the one surface  181  of the power module  110  from the inner side in the radial direction, while the inner wall surfaces  713   c  of the installation recess  713   b  can cool the lateral surfaces of the power module  110  in the circumferential direction γ and the axial direction α. Therefore, the cooling effect of the power module  110  installed in the installation recess  713   b  can be enhanced. 
     According to the present embodiment, the smoothing capacitor C 2  is installed inside the installation recess  713   b . In this case, similarly to the power module  110 , the installation surface  713   a  can cool the one surface of the smoothing capacitor C 2  from the inner side in the radial direction, while the inner wall surfaces  713   c  of the installation recess  713   b  can cool the lateral surfaces of the smoothing capacitor C 2  in the circumferential direction γ and the axial direction α. Therefore, the cooling effect of the smoothing capacitor C 2  installed in the installation recess  713   b  can be enhanced. 
     Further, the housing  703  has an annular shape, and the thickness dimension in the radial direction β is relatively small. Therefore, the temperature distribution of the refrigerant in the radial direction β in the housing flow path  711 , specifically, the temperature difference between the inner cooling part  712  and the outer cooling part  713  is less likely to occur. As a result, the stator  701  can be effectively cooled by the inner cooling part  712 , and the power modules  110  and the smoothing capacitors C 2  can be effectively cooled by the outer cooling part  713 . 
     The power module  110  also includes the cooling unit  120 . The flow path  126  of the cooling unit  120  is in communication with the housing flow path  711  so that the refrigerant flows from the housing flow path  711  into the flow path  126  of the cooling unit  120  and flows again into the housing flow path  711  from the flow path  126  of the cooling unit  120 . In this way, the refrigerant can be introduced from the housing  703  into the cooling unit  120  inside of the power module  110 , and thus the semiconductor device  20  can be cooled inside of the power module  110 . The semiconductor device  20  is arranged on the surface of the cooling unit  120 . Therefore, the semiconductor device  20  can be effectively cooled. Further, in the cooling unit  120 , the capacitor C 1  is arranged on the opposite side of the semiconductor device  20 . Therefore, the capacitor C 1  can also be effectively cooled. The capacitor C 1  corresponds to a module capacitor. 
     In the housing  703 , the housing flow path  711  is separated into the upstream region  234   a  and the downstream region  234   b . The flow path  126  of the power module  110  connects the upstream region  741  and the downstream region  742 . In such a configuration, the refrigerant easily flows into the flow path  126  of the cooling unit  120 . Therefore, the semiconductor device  20  and the capacitor C 1  can be cooled more effectively. 
     As another example shown in  FIG. 36 , the power module  110  may be arranged with respect to the housing  703  having the housing flow path  711  that is not partitioned, and the flow path  126  may be connected to the housing flow path  711 . For example, the housing flow path  711  is not separated into the inflow region  741  and the outflow region  742 .  FIG. 36  corresponds to  FIG. 35 . However, in consideration of the size of the power module  110 , the cross-sectional area of the flow path  126  is smaller than that of the housing flow path  711  in the flow direction of the refrigerant. The housing flow path  711  is a main flow path common to the plurality of power modules  110 , and the flow path  126  of the cooling unit  120  is a sub flow path. Therefore, as shown in the present example, it is preferable to employ the configuration in which the refrigerant can easily flow into the cooling unit  120 . 
     Although not shown, the housing  703  may, for example, have a connecting region connecting the inflow region  741  and the outflow region  742 , and the cross-sectional area of this connecting region may be smaller than the inflow region  741  and the outflow region  742 . When the housing  703  has the connecting region, the resistance of the refrigerant flowing from the inflow region  741  to the outflow region  742  is increased, and the refrigerant can easily flow toward the cooling unit  120 . However, the configuration shown in the present example is more effective. 
     Further, the heat exchange parts  123  of the cooling unit  120  are arranged in two stages. That is, the cooling unit  120  is branched into two stages in the Z direction. The cooling unit  120  (the heat exchange parts  123 ) is provided with inner fins to have a higher heat transfer coefficient than the outer cooling part  713  of the housing  703 . The semiconductor device  20  is interposed between the heat exchange parts  123  of the two stages, and the capacitor C 1  is arranged on the side opposite to the semiconductor device  20  with respect to at least one of the heat exchange parts  123  of the two stages. In this configuration, the semiconductor device  20  can be cooled by the heat exchange parts  123  of the two stages, on both sides in the Z direction. Therefore, the semiconductor device  20  can be cooled more effectively. Further, the capacitor C 1  can be cooled by the heat exchange part  123 . Accordingly, the capacitor C 1  can be effectively cooled. 
     Further, the capacitor C 1  is arranged on the opposite side to the semiconductor device  20  with respect to the heat exchange part  123  of one of the two stages, and the drive substrate  160  is arranged on the opposite side to the semiconductor device  20  with respect to the heat exchange part  123  of the other one of the two stages. Further, the signal terminals  80  of the semiconductor device  20  is connected to the drive substrate  160 . In such a configuration, the drive substrate  160  can be cooled while reducing the size in the direction orthogonal to the Z direction. Moreover, the signal terminals  80  can be shortened. Since the semiconductor device  20  and the drive substrate  160  can be connected in a shorter distance, it is possible to suppress the delay of the on and off timings of the switching elements Q 1  and Q 2 . In addition, noise resistance can be improved. 
     The electric power conversion device  5  includes the smoothing capacitor C 2 , in addition to the multiple power modules  110  constituting the inverter  7 . The capacitance of the smoothing capacitor C 2  is larger than the capacitance of the capacitor C 1  of each power module  110 . In this way, since the smoothing capacitor C 2  is provided separately from the capacitors C 1 , it is sufficient that the capacitors C 1  have a function of supplying the electric charges required for switching the switching elements Q 1  and Q 2  constituting the upper and lower arm circuits  10  connected in parallel. Therefore, the size of the capacitors C 1  can be reduced. Further, since the electric power conversion device  5  has the smoothing capacitor C 2 , fluctuations of the DC voltage can be suppressed. In the present example, particularly, the capacitor C 1  and the upper and lower arm circuit  10  are connected to the VH line  12 H and the N line  13  as the electric power lines via the common wirings  11 P and  11 N. Specifically, the capacitor C 1  and the upper and lower arm circuit  10  are connected to the VH bus bar  284  and the N bus bar  282  via the common wiring portions  132  and  142 . Therefore, as described above, the surge voltage can be suppressed. The capacitor C 1  corresponds to a first capacitor, and the smoothing capacitor C 2  corresponds to a second capacitor. 
     The power module  110  employed to the electric power conversion device  5  is not limited to have the configuration shown in the present example. For example, the power module  110  including the semiconductor device  20  of the 2-in-1 package structure as described above can also be adopted. Further, as the main terminals  70 , those having various configurations as described above can be adopted. The example in which the power module  110  has the drive substrate  160  has been described. However, the present embodiment is not limited to such an example. Similarly to the control substrate  290 , the drive substrate  160  may be provided separately from the power module  110 . In such a case, as shown in  FIG. 37 , the power module  110  is not provided with the drive substrate  160  between the heat exchange part  123  of the second stage and the rear surface  182 . 
     Further, the power module  110  may not have the capacitor C 1 . In such a configuration, as shown in  FIG. 38 , the power module  110  has the drive substrate  160 , for example, between the heat exchange part  123  of the first stage and the housing  703 , in place of the capacitor C 1 . In this configuration, the drive substrate  160  is cooled by the outer cooling part  713  of the housing  703 . 
     The example in which the semiconductor device  20  is arranged between the heat exchange parts  123  of the two stages in the power module  110  has been described. However, the present embodiment is not limited to such an example. The capacitor C 1  may be arranged between the heat exchange parts  123  of the two stages, and the semiconductor device  20  may be arranged between the housing  703  and the heat exchange part  123  of the first stage. However, it is preferable to cool the semiconductor device  20  having a larger temperature change per unit time between the heat exchange parts  123  of the two stages. 
     The example in which the semiconductor device  20  is arranged adjacent to the housing  703  in the power module  110  has been described. However, the present embodiment is not limited to such an example. The capacitor C 1  may be arranged between the heat exchange part  123  and the housing  703 . However, it is preferable to cool the semiconductor device  20  having a larger temperature change per unit time between the heat exchange part  123  and the housing  703 . 
     The plurality of power modules  110  arranged in the circumferential direction γ may be displaced in the radial direction β. The power module  110  and the smoothing capacitor C 2  may be arranged next to each other in the circumferential direction γ. The plurality of smoothing capacitors C 2  may be arranged next to each other in the axial direction α. Further, the plurality of power modules  110  may not be equidistant from the center line CL 2  in the radial direction β. Even in this case, it can be regarded that the power modules  110  are still arranged in the circumferential direction γ. 
     The power module  110  and the smoothing capacitor C 2  may not be in a state of extending in the tangential direction orthogonal to the radial direction β, but may be in a state of being inclined with respect to the tangential direction. That is, the one surface  181  of the power module  110  or the one surface of the smoothing capacitor C 2  may not be orthogonal to the radial direction β. For example, it is assumed that the power modules  110 , which are arranged in the circumferential direction γ, are parallel to each other. In this configuration, on the outer peripheral surface of the housing  703 , one of the plurality of power modules  110  is placed in a direction in which the one surface  181  is orthogonal to the radial direction β, and the remaining power modules  110  are placed in a state of being parallel to the one. In this configuration, the plurality of power modules  110  may be arranged in a straight line in the tangential direction. Even in this case, it can be regarded that the power modules  110  are still arranged in the circumferential direction γ. 
     The number of power modules  110  attached to the housing  703  may be less than three or more than three. Further, the number of smoothing capacitors C 2  attached to the housing  703  may not be the same as that of the power modules  110 . Further, among the components constituting the electric power conversion device  5 , components different from the power modules  110  and the smoothing capacitors C 2  may be individually attached to the housing  703 . 
     The inner wall surface  713   c  of the installation recess  713   b  may be in contact with the power module  110  and the smoothing capacitor C 2  without being separated from the power module  110  and the smoothing capacitor C 2  in the radial direction β and the axial direction α. In this case, the cooling effect of the power module  110  and the smoothing capacitor C 2  by the inner wall surface  713   c , which is a part of the outer peripheral surface of the outer cooling part  713 , can be enhanced. 
     In the housing  703 , the installation surface  713   a  on which the power module  110  and the smoothing capacitor C 2  are installed may not be the bottom surface of the installation recess  713   b . That is, the power module  110  and the smoothing capacitor C 2  may be installed in a state of protruding outward in the radial direction from the outer peripheral surface of the housing  703  without being housed in the installation recess  713   b.    
     The housing flow path  711  may not go around the housing  703  in the circumferential direction γ. For example, the housing flow path  711  may not be provided in the portion of the housing  703  that extends along the flow path  126  of the power module  110 . Even in this configuration, the power module  110  can be cooled from the inside by the refrigerant flowing through the flow path  126 . Further, the housing flow path  711  may be provided with respect to the end surface of the housing  703 . For example, it is assumed that the housing flow path  711  is provided at an end face portion forming the end face of the housing  703 . In this configuration, the end face portion serves as a cooling portion having thermal conductivity, and this cooling portion can cool the stator  701  from the outside in the axial direction α. Further, the power module  110  and the smoothing capacitor C 2  may be attached to the end face portion. 
     It is sufficient that at least a part of the power module  110  and at least a part of the smoothing capacitor C 2  is aligned with the housing flow path  711  in the radial direction β. Further, the power module  110  and the smoothing capacitor C 2  may not be aligned with the housing flow path  711  in the radial direction  13 . That is, the power module  110 , the smoothing capacitor C 2 , and the housing flow path  711  may be arranged at positions displaced from each other in the radial direction β or the circumferential direction γ. 
     The housing  703  may have a plurality of the housing flow paths  711 . For example, it is assumed that the plurality of housing flow paths  711  are provided so as not to exchange refrigerants with each other. The power modules  110  may be arranged for one of the housing flow paths  711 , and the smoothing capacitors C 2  may be arranged for the other housing flow path  711 . 
     The housing  703  may have a plurality of the outer cooling parts  713 . For example, the power module  110  and the smoothing capacitor C 2  may be provided in separate outer cooling parts  713 . The plurality of power modules  110  may be individually arranged for the outer cooling parts  713 . The plurality of smoothing capacitors C 2  may be individually arranged for the outer cooling parts  713 . 
     Second Embodiment 
     The present embodiment can refer to the preceding embodiment. Therefore, the descriptions of the parts common to the drive system  1 , the electric power conversion device  5 , the semiconductor device  20 , the power module  110 , and the motor unit  800  described in the preceding embodiment will be omitted. 
     As shown in  FIG. 39 , in the present embodiment, the cooling unit  120  of the power module  110  has the heat exchange part  123  of one stage.  FIG. 39  corresponds to  FIG. 35 . Also in the present embodiment, the refrigerant flows from the housing flow path  711  into the flow path  126  of the power module  110 . The semiconductor device  20  is arranged between the heat exchange part  123  and the housing  703 , and the capacitor C 1  connected in parallel to the semiconductor device  20  is arranged on the side opposite to the semiconductor device  20  with respect to the heat exchange part  123 . The power module  110  may not have the drive substrate  160 . The other configurations are similar to those of the preceding embodiment (for example, see  FIG. 35 ). 
     Also in the present embodiment, the semiconductor device  20  and the capacitor C 1  are thus arranged in the Z direction. Further, the power modules  110  each having such a configuration are arranged on the outer peripheral surface of the housing  703 . Therefore, it is possible to reduce the size of the electric power conversion device  5  in the direction orthogonal to the Z direction while enabling the cooling of the semiconductor device  20 . 
     Further, in the same power module  110 , the semiconductor device  20  is arranged closer to the housing  703  than the capacitor C 1 . Therefore, the semiconductor device  20  can be effectively cooled by the refrigerant flowing through the housing  703 . 
     Further, the semiconductor device  20  is arranged between the heat exchange part  123  and the housing  703 . Therefore, the semiconductor device  20  can be cooled on both sides in the Z direction by the heat exchange part  123  and the housing  703 . As a result, the semiconductor device  20  can be further effectively cooled. The capacitor C 1  can also be cooled by the heat exchange part  123 . 
     The heat exchange part  123  is not particularly limited to the configuration shown in  FIG. 39 . For example, as shown in  FIG. 36 , it may have a configuration having an undivided housing flow path  711  or a configuration having the above-mentioned connecting region. 
     In the power module  110 , the example in which, of the capacitor C 1  and the drive substrate  160 , only the capacitor C 1  is arranged on the side opposite to the semiconductor device  20  with respect to the heat exchange part  123  has been described. However, the present embodiment is not limited to such a configuration. For example, as shown in  FIG. 40 , the drive substrate  160  may be provided on the side opposite to the semiconductor device  20  with respect to the heat exchange part  123 . Further, as shown in  FIG. 41 , both of the capacitor C 1  and the drive substrate  160  may be provided on the side opposite to the semiconductor device  20  with respect to the heat exchange part  123 . In this configuration, the capacitor C 1  is provided between the heat exchange part  123  and the drive substrate  160 . 
     Third Embodiment 
     The present embodiment can refer to the preceding embodiment. Therefore, the description of the parts common to the drive system  1 , the electric power conversion device  5 , the semiconductor device  20 , the power module  110 , and the motor unit  800  shown in the preceding embodiment will be omitted. As shown in  FIG. 42 , in the present embodiment, the power module  110  does not have the cooling unit  120  and the drive substrate  160  described above. Also in this embodiment, the power module  110  is arranged in the outer cooling part  713  of the housing  703 . Inside the power module  110 , the semiconductor device  20  is arranged adjacent to the outer cooling part  713  of the housing  703 . Further, the housing flow path  711  is not separated into the upstream and the downstream. The other configurations are similar to those of the preceding embodiment (for example, see  FIG. 35 ). 
     Also in the present embodiment, the semiconductor device  20  and the capacitor C 1  are arranged in the Z direction as described above. Then, the power module  110  having such a configuration is arranged on the outer cooling part  713  of the housing  703 . Therefore, it is possible to reduce the size of the electric power conversion device  5  in the direction orthogonal to the Z direction while enabling the cooling of the semiconductor device  20 . 
     Further, in the same power module  110 , the semiconductor device  20  is arranged closer to the outer cooling part  713  of the housing  703  than the capacitor C 1 . Therefore, the semiconductor device  20  can be effectively cooled by the outer cooling part  713 . 
     The example in which the semiconductor device  20  is arranged adjacent to the outer cooling part  713  in the power module  110  has been described. However, the present embodiment is not limited to such a configuration. The capacitor C 1  may be arranged adjacent to the outer cooling part  713 . However, it is preferable to cool the semiconductor device  20  having a large temperature change per unit time on the side adjacent to the outer cooling part  713 . 
     Fourth Embodiment 
     The present embodiment can refer to the preceding embodiment. Therefore, the descriptions of the parts common to the drive system  1 , the electric power conversion device  5 , the semiconductor device  20 , the power module  110 , and the motor unit  800  shown in the preceding embodiment will be omitted. 
     As shown in  FIGS. 43 and 44 , in the present embodiment, the power module  110  is accommodated in the housing flow path  711 . The power modules  110  are arranged to extend in the axial direction α inside the housing flow path  711 . The power modules  110  are separated in a radially outward direction from the inner cooling part  712 , and is separated in a radially inward direction from the outer cooling part  713 . In the housing flow path  711 , the refrigerant flows between the power modules  110  and the inner cooling part  712 , as well as between the power modules  110  and the outer cooling part  713 . The one surface  181  of the power module  110  faces the inner cooling part  712 , and the rear surface  182  of the power module  110  faces the outer cooling part  713 . In the housing flow path  711 , each of the one surface  181  and the rear surface  182  of the power module  110  is directly cooled by the refrigerant. 
     In the present embodiment, the housing flow path  711  is not separated into the inflow region  741  and the outflow region  742 . The housing  703  has the first partition portion  743 , but does not have the second partition  744 . Similarly to the first embodiment as described above, the refrigerant flowing from the inflow hole  715  into the housing flow path  711  flows in the housing flow path  711  to go around one turn in the circumferential direction γ, and then flows out from the outflow hole  716 . Further, the plurality of power modules  110  are arranged at predetermined intervals in the circumferential direction γ, similarly to the first embodiment described above. Therefore, in the housing flow path  711 , the refrigerant flowing from the inflow hole  715  passes through the plurality of power modules  110  one by one in order. 
     The housing  703  is provided with an insertion hole  703   a  that allows the power module  110  to be inserted into the housing flow path  711 . The insertion hole  703   a  is provided at one end of the housing  703 . The insertion hole  703   a  penetrates the housing  703  in the axial direction α, and the power module  110  closes the insertion hole  703   a  in a state of being inserted into the housing flow path  711  through the insertion hole  703   a . In the insertion hole  703   a , the connection portion between the power module  110  and the housing  703  is hermetically sealed with a sealing material or the like. In this case, at least a part of the power module  110  is immersed in the refrigerant in the housing flow path  711 . In particular, the semiconductor device  20  is arranged at a position inside the housing flow path  711  in both the axial direction α and the radial direction β. 
     Both the output bus bar  150  of the power module  110  and the connection terminal  701   d  of the stator  701  are arranged adjacent to the one end surface of the housing  703  in the axial direction α. The connection terminal  701   d  is a terminal extending from the stator winding  706  of the stator  701 . The output bus bar  150  and the connection terminal  701   d  extend in the axial direction α from the power module  110  and the stator  701 . In this configuration, the connection between the output bus bar  150  and the connection terminal  701   d  can be simplified, and the work load for the connection can be reduced. Further, since the output bus bar  150  can be shortened as much as possible, power loss and heat generation in the output bus bar  150  can be suppressed. 
     According to the present embodiment, the power module  110  is accommodated in the housing flow path  711  in a state where the refrigerant flows along both sides of the power module  110 . In this configuration, since both the one surface  181  and the rear surface  182  of the power module  110  are directly cooled by the refrigerant, the cooling effect of the power module  110  by the refrigerant flowing through the housing flow path  711  can be enhanced. Further, in the state where the plurality of power modules  110  are immersed in the refrigerant in the housing flow path  711 , all of the power modules  110  are directly cooled by the refrigerant. Therefore, it is possible to suppress that the cooling effect of the refrigerant varies between the power modules  110 . 
     The power module  110  may be accommodated in the housing flow path  711  in a state of extending in the radial direction α. For example, as shown in  FIG. 45 , it is assumed that the insertion hole  703   a  is provided in the outer cooling part  713 . In this configuration, the power module  110  is inserted into the housing flow path  711  through the insertion hole  703   a  in a state of extending in the radial direction β, and the output bus bar  150  is provided radially outside the housing  703 . Further, the power module  110  may be housed in the housing flow path  711  in a direction in which the output bus bar  150  is arranged side by side in the housing  703  in the radial direction β. 
     In the housing flow path  711 , the power module  110  may be in contact with at least one of the inner cooling part  712  and the outer cooling part  713 . For example, in a configuration in which the power module  110  is in contact with only one of the inner cooling part  712  and the outer cooling part  713 , there is a high possibility that the refrigerant does not flow between the one of the inner cooling part  712  and the outer cooling part  713 , but the refrigerant flows between the other of the inner cooling part  712  and the outer cooling part  713  and the power module  110 . Therefore, the refrigerant can cool the power module  110  from the side adjacent to the other of the inner cooling part  712  and the inner cooling part  713 . Further, even in a configuration in which the power module  110  is in contact with both the inner cooling part  712  and the outer cooling part  713 , the refrigerant flows away from the power module  110  in the axial direction α, so that the power module  110  can be cooled by the refrigerant. 
     In the power module  110  of the present embodiment, the entirety of the semiconductor device  20  is located inside the housing flow path  711 . Alternatively, only a part of the semiconductor device  20  may be located inside the housing flow path  711 . That is, at least a part of the semiconductor device  20  may be located inside the housing flow path  711 . 
     In the present embodiment, the smoothing capacitor C 2  is attached to the outer peripheral surface of the housing  703 , similarly to the first embodiment described above. On the other hand, the smoothing capacitor C 2  may be accommodated inside the housing flow path  711 , similarly to the power module  110 . Similarly to the power module  110 , the smoothing capacitor C 2  may be accommodated inside the housing flow path  711  in a state of extending in the axial direction α, or may be accommodated inside the housing flow path  711  in a state of extending in the radial direction β. Further, similarly to the power module  110 , the smoothing capacitor C 2  may be in contact with at least one of the outer cooling part  713  and the inner cooling part  712 . 
     The housing  703  may not have the outer cooling part  713 . That is, the outer peripheral portion of the housing  703  may not have the outer cooling part  713 . Also in this case, the housing  703  can be cooled by the refrigerant as long as the smoothing capacitor C 2  is accommodated in the housing flow path  711 . 
     Fifth Embodiment 
     The present embodiment can refer to the preceding embodiment. Therefore, the description of the parts common to the drive system  1 , the electric power conversion device  5 , the semiconductor device  20 , the power module  110 , and the motor unit  800  shown in the preceding embodiments such as the fourth embodiment will be omitted. 
     In the present embodiment, as shown in  FIG. 46  and  FIG. 47 , differently from the fourth embodiment described above, the housing flow path  711  includes an inner flow path  751  and an outer flow path  752  located radially outside the inner flow path  751 . The inner flow path  751  and the outer flow path  752  both extend along the radial direction β. The outer flow path  752  is in communication with the inflow hole  715 , and the inner flow path  751  is in communication with the outflow hole  716 . In the housing flow path  711 , the outer flow path  752  is arranged upstream of the inner flow path  751 . 
     The inner flow path  751  has an annular shape that extends one turn in the circumferential direction γ, and the outer flow path  752  has a shape that does not extend one turn around the center line CL 2 . The outer flow path  752  is arranged next to the inner flow path  751  in the radial direction β. The housing  703  has an inner/outer partition portion  753  that separates the inner flow path  751  and the outer flow path  752 . The inner/outer partition portion  753  is provided between the inner flow path  751  and the outer flow path  752  in the radial direction β, and extends in the circumferential direction γ. The inner/outer partition portion  753  is formed of a material having thermal conductivity, similarly to the inner cooling part  712  and the outer cooling part  713 . 
     The plurality of power modules  110  are accommodated in the outer flow path  752  of the housing flow path  711 . In this case, the power modules  110  are provided between the inner/outer partition portion  753  and the outer flow path  752  in the radial direction β. 
     The power module  110  is in a state of extending in the axial direction α inside the outer flow path  752 . The power module  110  is separated radially outward from the inner/outer partition portion  753 , and is separated radially inward from the outer cooling part  713 . In the outer flow path  752 , the refrigerant flows between the power module  110  and the inner/outer partition portion  753 , as well as between the power module  110  and the outer cooling part  713 . The one surface  181  of the power module  110  faces the inner/outer partition portion  753 , and the rear surface  182  of the power module  110  faces the outer cooling part  713 . In the outer flow path  752 , each of the one surface  181  and the rear surface  182  of the power module  110  is directly cooled by the refrigerant. 
     In the housing flow path  711 , the refrigerant flowing from the inflow hole  715  into the outer flow path  752  passes through each power module  110 , flows into the inner flow path  751 , makes one turn in the circumferential direction γ in the inner flow path  751 , and then flows out from the hole  716 . Further, the plurality of power modules  110  are arranged at predetermined intervals in the circumferential direction γ, similarly to the first embodiment described above. Therefore, in the outer flow path  752 , the refrigerant flowing from the inflow hole  715  passes through the plurality of power modules  110  one by one in order. 
     According to the present embodiment, the power modules  110  are accommodated in the outer flow path  752  with the refrigerant flowing along both sides of each power module  110 . In this configuration, since both the one surface  181  and the rear surface  182  of the power module  110  are directly cooled by the refrigerant, the cooling effect of the power module  110  by the refrigerant flowing through the outer flow path  752  can be enhanced. Further, in the state where the plurality of power modules  110  are immersed in the refrigerant in the outer flow path  752 , all of the power modules  110  are directly cooled by the refrigerant. Therefore, it is less likely that the cooling effect of the refrigerant will be varied between the power modules  110 . 
     According to the present embodiment, in the housing flow path  711 , the outer flow path  752  for cooling the respective power modules  110  is provided upstream of the inner flow path  751  for cooling the stator  701 . In this configuration, the power modules  110  can be cooled by the refrigerant flowing from the inflow hole  715  into the housing flow path  711  in a state where the temperature has not risen. In other words, it is possible to restrict the refrigerant whose temperature has risen due to the cooling of the stator  701  from cooling the power modules  110 . 
     Here, the stator  701  has a relatively low responsiveness to temperature changes, and the power modules  110  have a relatively high responsiveness to temperature changes. That is, the temperature of the stator  701  is less likely to change, but the temperature of the power modules  110  is likely to change as the vehicle travels. The temperature of both the stator  701  and the power module  110  rises as the vehicle travels. However, when the vehicle is temporarily stopped due to a traffic signal or the like, the temperature of the stator  701  hardly drops during such a short stop period, whereas the temperature of the power module  110  drops to some extent even in such a short stop period. Then, when the vehicle starts traveling again, the temperature of the power modules  110  tends to rise sharply. In this case, since the power modules  110  are housed in the outer flow path  752  provided on the upstream side in the housing flow path  711 , it is effective for the motor unit  800  at the start of traveling to cool the power modules  110  by the refrigerant whose temperature has not risen. 
     It is not always necessary that the outer flow path  752  extends along the inner flow path  751  as long as the outer flow path  752  is housed in the housing  703 . For example, it is assumed that the inner flow path  751  and the outer flow path  752  are not arranged in the radial direction β. Even in this configuration, if the distance from the inner peripheral surface of the housing  703  in the radial direction β is larger in the outer flow path  752  than in the inner flow path  751 , the refrigerant flowing in the outer flow path  752  cools the power modules  110  prior to the stator  701 . 
     As examples of the configuration in which the housing flow path  711  exist on both the one surface  181  and the rear surface  182  of the power module  110 , in addition to the configuration of the present embodiment, there is a configuration in which the power modules  110  are arranged between the inner flow path  751  and the outer flow path  752  in the radial direction β. In this configuration, an accommodating portion such as a hole is provided in the inner/outer partition portion  753 , and the power module  110  is accommodated in this accommodating portion. In this case, the inner/outer partition portion  753  cools the power module  110  with the refrigerant flowing through the inner flow path  751  and the outer flow path  752 . 
     The present disclosure is not limited to the embodiments illustrated. The present disclosure encompasses the illustrated embodiments and modifications based on the embodiments by those skilled in the art. For example, the disclosure is not limited to the combination of elements shown in the embodiments. The present disclosure may be implemented in various combinations. The plurality of embodiments can be combined without any inconsistency. Each embodiment or an embodiment obtained by combining a plurality of embodiments embodies technical ideas from various viewpoints. 
     The example in which the electric power conversion device  5  constitutes the inverter  7  for the motor generator  3  and the smoothing capacitor C 2  is shown, but the present disclosure is not limited thereto. In the present disclosure, the power modules  110  are necessarily cooled by the refrigerant flowing in the housing flow path  711 . The electric power conversion device  5  may be configured to include only the power modules  110  constituting the inverter  7 . The electric power conversion device  5  may not have the smoothing capacitor C 2  in a case where the capacitors C 1  have a function of smoothing the DC voltage. In such a case, in the three-phase inverter, the capacitance of the capacitor C 1  of each parallel circuit  11  is, for example, about 300 μF. 
     Explanations of the reference numerals are added hereinafter. Reference numeral  3  indicates a motor generator as a rotary electric machine. Reference numeral  5  indicates an electric power conversion device. Reference numeral  10  indicates an upper and lower arm circuit. Reference numerals  20 ,  20 U, and  20 L indicate semiconductor devices. Reference numeral  20   a  indicates one surface. Reference numeral  20   b  indicates a rear surface. Reference numeral  110  indicates a power module. Reference numeral  120  indicates a cooling unit as a module cooling unit. Reference numeral  126  indicates a flow path as a module flow path. Reference numeral  150  indicates an output bus bar as an output terminal. Reference numeral  181  indicates one surface. Reference numeral  182  indicates a rear surface. Reference numeral  701  indicates a stator. Reference numeral  702  indicates a rotor. Reference numeral  703  indicates a housing. Reference numeral  711  indicates a housing flow path. Reference numeral  712  indicates an inner cooling part as a first cooling part and a housing cooling part. Reference numeral  713  indicates an outer cooling part as the second cooling part. Reference numeral  715  indicates an inflow hole. Reference numeral  716  indicates an outflow hole. Reference numeral  741  indicates an inflow region as an opposing portion. Reference numeral  742  indicates an outflow region as an upstream side portion. Reference numeral  751  indicates an inner flow path. Reference numeral  752  indicates an outer flow path. Reference numeral  800  indicates a motor unit as a rotary electric machine unit. Reference numeral C 1  indicates a capacitor as a module capacitor. Reference numeral C 2  indicates a smoothing capacitor. Reference numeral CL 2  indicates a center line. Reference numeral a indicates an axial direction. Reference numeral γ indicates a circumferential direction.