Patent Publication Number: US-2023133289-A1

Title: Power control device, electric motor including power control device, and air-conditioning apparatus including electric motor

Description:
TECHNICAL FIELD 
     The present disclosure relates to a power control device that controls power supply, to an electric motor including the power control device, and to an air-conditioning apparatus including the electric motor. 
     BACKGROUND ART 
     Conventionally, an electric motor includes a power control device that controls driving of a motor body including a rotor, a stator, and other components. The power control device includes a substrate on which a power transistor, a microcomputer, and other components are mounted. For the substrate, for example, an annular substrate is adopted that has a through hole through which a rotary shaft of the rotor, and the like is caused to pass (see Patent Literature 1, for example). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2015-171200 
     SUMMARY OF INVENTION 
     Technical Problem 
     In a conventional technique disclosed in Patent Literature 1, heat from heat generating parts, such as a power transistor, is transferred to a microcomputer, thus causing the temperature of the microcomputer to rise to a temperature equal to or higher than the operation guarantee temperature. Particularly in the case where a substrate and a stator are integrally molded by using a resin, heat from the heat generating parts is easily transferred to the microcomputer via the resin and hence, the temperature of the microcomputer significantly rises. As a result, there is the problem that it is difficult to achieve a high output and a reduction in size of an electric motor. 
     The present disclosure has been made to solve the above-mentioned problem, and it is an object of the present disclosure to provide a power control device that can suppress a rise in temperature of the microcomputer, to provide an electric motor including the power control device, and to provide an air-conditioning apparatus including the electric motor. 
     Solution to Problem 
     A power control device according to one embodiment of the present disclosure is a power control device that drives an electric motor including a rotor into which a rotary shaft is inserted and a stator; the stator being provided on an outer peripheral side of the rotor, the power control device including: a substrate having a through hole and disposed to face the rotor and the stator, the rotary shaft being caused to pass through the through hole; a power semiconductor module mounted on the substrate and including a drive circuit; and a microcomputer mounted on the substrate, and configured to control power supplied to the electric motor, wherein the substrate is integrally formed with the stator by using a molded resin, and a first part having a lower thermal conductivity than the molded resin is disposed on the substrate at a position between the power semiconductor module and the microcomputer. 
     An electric motor according to another embodiment of the present disclosure is an electric motor including: the rotor into which a rotary shaft is inserted; the stator provided on an outer peripheral side of the rotor; and the above-mentioned power control device. 
     An air-conditioning apparatus according to still another embodiment of the present disclosure is an air-conditioning apparatus including: an indoor unit; and an outdoor unit, wherein at least one of the indoor unit and the outdoor unit includes a fan, and the above-mentioned electric motor is provided as a power source for the fan. 
     Advantageous Effects of Invention 
     In the power control device according to one embodiment of the present disclosure, the first part having a lower thermal conductivity than the molded resin is disposed on the substrate at a position between the power semiconductor module and the microcomputer. Therefore, a low thermal conductivity is achieved between the power semiconductor module and the microcomputer, so that heat from the power semiconductor module is prevented from being easily transferred to the microcomputer and hence, it is possible to suppress a rise in temperature of the microcomputer. As a result, it is possible to achieve a higher output and a further reduction in size of the electric motor including the power control device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic cross-sectional view showing a configuration of an electric motor according to Embodiment 1. 
         FIG.  2    is a circuit diagram showing a constitutional example of a circuit of a power control device included in the electric motor according to Embodiment 1. 
         FIG.  3    is a schematic view showing a schematic configuration of a substrate of the power control device included in the electric motor according to Embodiment 1 as viewed from an opposite stator side. 
         FIG.  4    is a first schematic view showing a schematic configuration of a substrate of a power control device included in a conventional electric motor as viewed from an opposite stator side. 
         FIG.  5    is a schematic view showing a schematic configuration of a first modification of the substrate of the power control device included in the electric motor according to Embodiment 1 as viewed from the opposite stator side. 
         FIG.  6    is a schematic view showing a schematic configuration of a second modification of the substrate of the power control device included in the electric motor according to Embodiment 1 as viewed from the opposite stator side. 
         FIG.  7    is a schematic view showing a cross section of a schematic configuration of the electric motor according to Embodiment 1, 
         FIG.  8    is a second schematic view showing the schematic configuration of the substrate of the power control device included in the electric motor according to Embodiment 1 as viewed from the opposite stator side. 
         FIG.  9    is a schematic view showing a cross section of a schematic configuration of a first modification of the electric motor according to Embodiment 1. 
         FIG.  10    is a schematic view showing a cross section of a schematic configuration of a second modification of the electric motor according to Embodiment 1. 
         FIG.  11    is a schematic view showing a constitutional example of an air-conditioning apparatus according to Embodiment 2. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, Embodiments of the present disclosure will be described with reference to drawings. The present disclosure is not limited by Embodiments described below. In addition, the relationship of sizes of respective components in the following drawings may differ from that of the actual ones. 
     Embodiment 1 
       FIG.  1    is a schematic cross-sectional view showing a configuration of an electric motor  100  according to Embodiment 1.  FIG.  2    is a circuit diagram showing a constitutional example of a circuit of a power control device  10  included in the electric motor  100  according to Embodiment 1. 
     The electric motor  100  may be, for example, a brushless DC motor that is driven by an inverter. The electric motor  100  outputs power to a load connected to a rotary shaft  1 , which will be described later. As shown in  FIG.  1   , the electric motor  100  includes a motor body  100   a  and the power control device  10  that generates power for driving the motor body  100   a  in response to a speed command signal transmitted from a higher-level system of the electric motor  100 . In Embodiment 1, the higher-level system of the electric motor  100  means a control board of equipment that incorporates the electric motor  100 . For example, in the case where the electric motor  100  is incorporated in an air conditioner, a control board in an air conditioner unit corresponds to the higher-level system of the electric motor  100 . 
     The motor body  100   a  includes the rotary shaft  1 , a rotor  2 , an annular stator and an output-side bearing  4   a  and an opposite-output-side bearing  4   b , the rotary shaft  1  being inserted into the rotor  2 , the stator  3  being provided on the outer peripheral side of the rotor  2 , the output-side bearing  4   a  and the opposite-output-side bearing  4   b  rotatably supporting the rotary shaft  1 . The output-side bearing  4   a  is provided at one end of the rotary shaft  1 , and rotatably supports the rotary shaft  1  at the one end of the rotary shaft  1 . The opposite-output-side bearing  4   b  is provided at the other end of the rotary shaft  1 , and rotatably supports the rotary shaft  1  at the other end of the rotary shaft  1 . 
     The power control device  10  includes a substrate  5  disposed on the output side of the stator  3 . The substrate  5  includes a circuit that includes a power semiconductor module  11 , a microcomputer  12  (see  FIG.  2   , which will be described later), and a magnetic sensor  19 , such as a Hall IC, that detects the position of the rotor  2 . The substrate  5  is disposed to be perpendicular to the axial direction of the rotary shaft  1  at a position between the stator  3  and the output-side bearing  4   a , and is fixed to an insulator  3   b , which will be described later. Further, the stator  3  and the substrate  5  are integrally formed by using a molded resin  14  that forms a housing, thus forming a molded stator  30  in which the molded resin  14  forms an outer shell. In Embodiment 1, the molded resin  14  is formed by mixing a thermosetting resin, such as epoxy, with silica filler in a ratio of 10 to 20% of the thermosetting resin to 80 to 90% of silica filler, for example. 
     The molded stator  30  is obtained by integrally molding the stator  3  and the substrate  5 , and has a recessed portion (not shown in the drawing) formed such that the rotor  2  can be accommodated in the recessed portion. A conductive bracket  31  is fitted in an inner peripheral portion of the molded stator  30  to close an opening port of the recessed portion of the molded stator  30 , and an outer race of the opposite-output-side bearing  4   b  is fitted in the inside of the conductive bracket  31 . The substrate  5  has a through hole  5   a  through which the rotary shaft  1  and the output-side bearing  4   a  are caused to pass. That is, the substrate  5  is formed into an annular shape, and is disposed to face the rotor  2  and the stator  3 . The power semiconductor module  11  of the substrate  5  is connected with a winding  3   c , which will be described later, via a winding terminal. 
     The rotor  2  is made of a resin, for example, and includes a rotor body  2   a , a rotor magnet  2   b , and a sensor magnet  2   c , the rotor body  2   a  being provided on the outer peripheral side of the rotary shaft  1 , the rotor magnet  2   b  being disposed on the inner side of the molded stator  30  and being made of a permanent magnet disposed to face a stator core  3   a , which will be described later, the sensor magnet  2   c  being disposed at the end portion of the rotor magnet  2   b  on the substrate  5  side to face the magnetic sensor  19 . The rotor body  2   a  provides insulation between the rotary shaft  1  and the rotor magnet  2   b , and also provides insulation between the rotary shaft  1  and the stator core  3   a . The rotor magnet  2   b  is formed by injection molding bond magnet obtained by mixing ferrite magnet or rare earth magnet with a thermoplastic resin material. Magnets are incorporated in a mold for injection molding, and injection molding is performed while an orientation is applied. To dispose the sensor magnet  2   c  in the vicinity of the magnetic sensor  19  on the substrate  5 , the sensor magnet  2   c  is disposed at a predetermined position on the rotor  2  by using the rotary shaft  1  as the center of a circle. 
     In the stator  3 , the outer diameter of the sensor magnet  2   c  is smaller than the outer diameter of the rotor magnet  2   b , so that magnetic flux easily flows into the magnetic sensor  19  mounted on the substrate  5 . To reduce an influence of magnetic flux generated from the winding  3   c  of the stator  3  as much as possible, the magnetic sensor  19  is disposed at a position away from the winding  3   c , that is, at a position close to the rotary shaft  1 . In  FIG.  1   , the rotor magnet  2   b  and the sensor magnet  2   c  are formed from one magnet. However, the rotor magnet  2   b  and the sensor magnet  2   c  may be respectively formed from different magnets. 
     The stator  3  includes the stator core  3   a , the insulator  3   b , and the winding  3   c . The stator core  3   a  is formed by laminating a plurality of electromagnetic steel sheets. The insulator  3   b  is provided for providing insulation between the stator core  3   a  and the winding  3   c , and is integrally molded with the stator core  3   a . The winding  3   c  is wound around each slot of the stator core  3   a  with which the insulator  3   b  is integrally molded. 
     A lead-out portion  17  including a lead wire  6  is disposed on the substrate  5 , the lead wire  6  being connected with the higher-level system, Passive components, such as an operational amplifier, a comparator, a regulator, a diode, a resistor, a capacitor, and a fuse, are disposed on the substrate  5 , 
     As shown in  FIG.  2   , the power semiconductor module  11  includes a drive circuit  110  that includes six power transistors  11   x  ( 11   x   1  to  11   x   6 ) each of which is a switching element, such as an insulated gate bipolar transistor (IGBT). The drive circuit  110  is an inverter circuit that converts a voltage inputted from the outside to a three-phase AC voltage by the operation of each power transistor  11   x , and supplies the three-phase AC voltage to the motor body  100   a . The power semiconductor module  11  also includes circuits, such as a gate drive circuit  11   y  and a protection circuit  11   z.    
     The power semiconductor module  11  is also referred to as “intelligent power module (IPM)”. There may be a case where six power transistors  11   x  are individually formed. In such a case, the gate drive circuit  11   y  may be formed from one IC or may be formed from three ICs for three different phases. 
     There may also be a case where the gate drive circuit  11   y  and the microcomputer  12  are formed from one IC. Each power transistor  11   x  may be a superjunction MOSFET, a planar MOSFET, an IGBT, or other transistors. The microcomputer  12  controls power supplied to the electric motor  100 . For the microcomputer  12 , for example, it is possible to adopt a microcomputer in which a flash memory being a nonvolatile memory is incorporated. 
     The electric motor  100  being a brushless DC motor obtains rotational power by switching the six power transistors  11   x  in the power semiconductor module  11  at an appropriate timing according to the position of the magnetic pole of the rotor magnet  2   b . The microcomputer  12  generates and outputs switching signals for turning on or off the six power transistors  11   x.    
     The principle of the operation of the electric motor  100  will be described below. 
     First, the magnetic sensor  19  outputs a magnetic pole position detection signal indicating the position of the magnetic pole of the rotor magnet  2   b  to the microcomputer  12 , and the magnetic pole position detection signal is inputted into the microcomputer  12 . Next, the microcomputer  12  infers the position of the magnetic pole of the rotor  2  from the magnetic pole position detection signal inputted from the magnetic sensor  19 . Then, the microcomputer  12  generates a switching signal corresponding to the inferred position of the magnetic pole of the rotor  2  and a speed command signal outputted from the higher-level system, and outputs the switching signal to the power semiconductor module  11 . 
     The microcomputer  12  monitors voltages at both ends of an overcurrent detecting resistor  11 R. When the voltages at both ends of the overcurrent detecting resistor  11 R reach a voltage equal to or higher than a set voltage, the microcomputer  12  forcibly turns off the power transistors  11   x , thus achieving overcurrent protection. When the microcomputer  12  receives an overcurrent detection signal from a temperature sensing element (not shown in the drawing), the microcomputer  12  forcibly turns off the power transistors  11   x , thus achieving superheat protection. 
     As described above, the power control device  10  uses the microcomputer  12  instead of a dedicated IC for controlling power and hence, it is possible to control the motor with a high accuracy due to fine adjustment of control parameters and a complex control algorithm. 
     In the case where the power control device  10  includes the microcomputer  12  that incorporates a flash memory and where the power control device  10  has a flash rewriting function that can rewrite data in the flash memory after the electric motor  100  is completed, it is possible to correct various amounts of deviation after the electric motor  100  is completed. In this case, the microcomputer  12  is provided with a dedicated lead wire used for communicating signals for rewriting data in the flash memory, and data in the flash memory are rewritten via the dedicated lead wire by I2C communication, for example. 
     Examples of the amount of deviation that can be corrected after the electric motor  100  is completed include an amount of phase deviation between the position of the magnetic pole and a magnetic pole position detection signal and an amount of deviation from a design value, such as an overcurrent limit value. That is, the power control device  10  having the flash rewriting function can control the motor after measuring the above-mentioned various amounts of deviation and writing parameters based on which the amount of deviation is corrected in the flash memory. Therefore, the power control device  10  can suppress variation in phase deviation between the position of a magnetic pole and a magnetic pole position detection signal, in overcurrent limit values, and the like. 
     There are two types of magnetic sensor  19 , that is, a magnetic sensor  19  that outputs digital signals (hereinafter referred to as “Hall IC”) and a magnetic sensor  19  that outputs analog signals (hereinafter referred to as “Hall element”). There are two types of Hall IC, that is, a Hall IC where a sensor unit and an amplification unit are formed from different semiconductor chips, the sensor unit is made of a semiconductor other than silicon, and the amplification unit is made of silicon (hereinafter referred to as “non-silicon Hall IC”), and a Hall IC where the sensor unit and the amplification unit are formed from one silicon semiconductor chip. 
     The non-silicon Hall IC incorporates two chips and hence, the center of the sensor is disposed at a position different from the center of an IC body. A semiconductor, such as indium antimonide (InSb), is used for the sensor unit of the non-silicon Hall IC. The non-silicon semiconductor has the advantage that sensitivity is improved and an offset caused by stress distortion is smaller compared with a silicon semiconductor, for example. 
     The microcomputer  12  or the gate drive circuit  11   y  incorporates an overcurrent detection unit (not shown in the drawing). The overcurrent detection unit monitors the voltage of an overcurrent detection resistor. When the voltage of the overcurrent detection resistor reaches a voltage equal to or higher than a fixed voltage, the overcurrent detection unit turns off the power transistors  11   x , thus achieving overcurrent protection. 
     The brushless DC motor obtains rotational power by switching the six (in the case of three phases) power transistors  11   x  in the power semiconductor module  11  at an appropriate timing according to the position of the magnetic pole of the rotor magnet  2   b . The microcomputer  12  generates the switching signal. 
     The principle of this operation will be described hereinafter. 
     The magnetic sensor  19  infers the position of the magnetic pole of the rotor  2 . Then, the power transistors  11   x  are switched according to the position of the magnetic pole of the rotor  2  and a speed command signal outputted from the system (for example, the substrate in the unit). 
     When voltages at both ends of the overcurrent detection resistor reach a voltage equal to or higher than a fixed voltage, the overcurrent detection unit forcibly turns off the power transistors  11   x , thus achieving overcurrent protection. When the overcurrent detection unit receives a signal from the temperature sensing element, the overcurrent detection unit forcibly turns off the power transistors  11   x , thus achieving superheat protection. 
     In Embodiment 1, as described above, the position of the magnetic pole of the rotor magnet  2   b  is detected by the magnetic sensor  19 . However, the configuration is not limited to such a configuration. The position of the magnetic pole of the rotor magnet  2   b  may be detected by sensorless control. In the sensorless control, the position of the magnetic pole of the rotor magnet  2   b  is inferred from an electric current that flows through the winding  3   c  or from the voltage applied to and generated in the winding  3   c.    
     In this sensorless control, signals from a shunt resistor and a current sensor may be amplified by an operational amplifier or the like to detect electric currents. There may also be the case where a comparator is used to generate an interruption signal from this current signal, the interruption signal being inputted into the microcomputer  12  to achieve overcurrent protection. A voltage (for example, 15 V) that drives the gate of the power transistor  11   x  may differ from a microcomputer power supply voltage (for example, 5 V). Therefore, in such a case, a regulator is used to generate a different power supply from one power supply supplied from the outside. For example, a 15 V power supply is supplied from the outside, and the regulator generates a 5 V power supply. This regulator may be incorporated in the gate drive circuit  11   y  or the power semiconductor module  11 , 
       FIG.  3    is a schematic view showing a schematic configuration of the substrate  5  of the power control device  10  included in the electric motor  100  according to Embodiment 1 as viewed from an opposite stator side.  FIG.  4    is a first schematic view showing a schematic configuration of a substrate  50  of a power control device included in a conventional electric motor as viewed from an opposite stator side. 
     As shown in  FIG.  3   , the power semiconductor module  11  and the microcomputer  12  are mounted on a surface of the substrate  5  on a side opposite to the stator  3  side, Hereinafter, the surface of the substrate  5  on the stator  3  side is referred to as “stator side”, and the surface of the substrate  5  on a side opposite to the stator side is referred to as “opposite stator side”. A first part  13  having a lower thermal conductivity than the molded resin  14  is disposed on the substrate  5  at a position between the power semiconductor module  11  and the microcomputer  12 . Examples of the first part  13  include ICs with small power consumption, such as an operational amplifier and a comparator, and a fuse having a cavity therein. The first part  13  is a part having thermal conductivity of equal to or lower than 1 W/mk. The reason the above-mentioned ICs have a low thermal conductivity is that an epoxy resin used as a semiconductor sealing material has a low thermal conductivity. The first part  13  may be formed from a plurality of parts. The position between the power semiconductor module  11  and the microcomputer  12  means a position on the microcomputer  12  side of the power semiconductor module  11  and on the power semiconductor module  11  side of the microcomputer  12 . The first part  13  having a lower thermal conductivity than the molded resin  14  is disposed on the substrate  5  at the position between the power semiconductor module  11  and the microcomputer  12  as described above. With such a configuration, compared with a conventional case shown in  FIG.  4    where the first part  13  is not disposed on the substrate  5  at a position between the power semiconductor module  11  and the microcomputer  12 , the cross-sectional area of paths  16  through which heat is transferred from the power semiconductor module  11  to the microcomputer  12 , that is, the cross-sectional area of the molded resin  14  forming the paths  16  through which heat is transferred is reduced, and the length of the paths  16  through which heat is transferred from the power semiconductor module  11  to the microcomputer  12  increases. Therefore, heat is prevented from being easily transferred from the power semiconductor module  11  to the microcomputer  12 . Accordingly, in Embodiment 1, it is possible to suppress an increase in temperature of the microcomputer  12  compared with the conventional technique. 
     The microcomputer  12  is disposed on the surface of the substrate  5  on the opposite stator side and hence, heat from the winding  3   c  is prevented from being easily transferred to the microcomputer  12 . Accordingly, it is possible to further suppress an increase in temperature of the microcomputer  12 . 
       FIG.  5    is a schematic view showing a schematic configuration of a first modification of the substrate  5  of the power control device  10  included in the electric motor  100  according to Embodiment 1 as viewed from the opposite stator side. 
     Unlike a dedicated IC, such as an application specific integrated circuit (ASIC) or an application specific standard product (ASSP), the microcomputer  12  has a large circuit scale and high clock frequency, and is operated at high speed. Accordingly, it is difficult to increase a guarantee temperature of the microcomputer  12 , and costs increase. For this reason, the maximum operation guarantee temperature of the microcomputer  12  is lower than the maximum operation guarantee temperature of the dedicated IC. For example, the maximum operation guarantee temperature of the dedicated IC is 115 degrees C. In contrast, the maximum operation guarantee temperature of the microcomputer  12  is 85 degrees C. Such a difference becomes more significant when a flash memory that requires a special process is incorporated. In the case of a configuration where the substrate  5  is integrally molded by using the molded resin  14 , heat from the power semiconductor module  11  and heat from the winding  3   c  are easily transferred to the microcomputer  12  and hence, the temperature of the microcomputer  12  significantly increases. 
     In view of the above, as shown in  FIG.  5   , on the surface of the substrate  5  on the opposite stator side, a second part  15  having a higher thermal conductivity than the molded resin  14  is disposed at a position between the first part  13  and the power semiconductor module  11  and dose to the outer periphery of the substrate  5 . The position close to the outer periphery of the substrate  5  means a position that is closer to the outer periphery than to the inner periphery of the substrate  5 . The position between the first part  13  and the power semiconductor module  11  means a position on the power semiconductor module  11  side of the first part  13  and on the first part  13  side of the power semiconductor module  11 . Examples of the second part  15  include ICs with large power consumption, such as the regulator and the power semiconductor module  11 , the resistor, and the capacitor. The second part  15  is a part having thermal conductivity of equal to or higher than 3 W/mk. The reason the above-mentioned ICs have a high thermal conductivity is that a substance having a high thermal conductivity is mixed into an epoxy resin used as a semiconductor sealing material. The second part  15  may be formed from a plurality of parts. On the surface of the substrate  5  on the opposite stator side, the second part  15  is disposed at the position between the first part  13  and the power semiconductor module  11  and close to the outer periphery of the substrate  5  as described above. With such a configuration, heat from the power semiconductor module  11  escapes to the outside of the motor from the outer peripheral side of the substrate  5  via the second part  15  having a higher thermal conductivity than the molded resin  14  and hence, the amount of heat transferred to the microcomputer  12  reduces. Accordingly, it is possible to suppress an increase in temperature of the microcomputer  12 . 
       FIG.  6    is a schematic view showing a schematic configuration of a second modification of the substrate  5  of the power control device  10  included in the electric motor  100  according to Embodiment 1 as viewed from the opposite stator side. 
     As shown in  FIG.  6   , on the surface of the substrate  5  on the opposite stator side, the second part  15  is disposed at a position between the first part  13  and the power semiconductor module  11  and dose to the inner periphery of the substrate  5 . The position dose to the inner periphery of the substrate  5  means a position closer to the inner periphery than to the outer periphery of the substrate  5 . With such a configuration, heat from the power semiconductor module  11  escapes to the outside of the motor from the inner peripheral side of the substrate  5  via the second part  15  having a higher thermal conductivity than the molded resin  14  and hence, the amount of heat transferred to the microcomputer  12  reduces. Accordingly, it is possible to suppress an increase in temperature of the microcomputer  12 . That is, it is possible to obtain advantageous effects substantially equal to the above-mentioned advantageous effects. The second part  15  may be formed from a plurality of parts. 
       FIG.  7    is a schematic view showing a cross section of a schematic configuration of the electric motor  100  according to Embodiment 1. 
     As shown in  FIG.  7   , a heat sink  18  is disposed on the opposite stator side at a position that faces the substrate  5 , and the second part  15  is disposed on the surface of the substrate  5  on the opposite stator side at the position between the power semiconductor module  11  and the first part  13 . With such a configuration, heat easily escapes through the path from the first part  13  to the heat sink  18  the first part  13  having a lower thermal conductivity than the molded resin  14 . Accordingly, heat is further prevented from being easily transferred to the microcomputer  12 . In this case, it is not necessary to dispose the second part  15 , having a higher thermal conductivity than the molded resin  14 , at a position close to the outer periphery or the inner periphery of the substrate  5 , 
       FIG.  8    is a second schematic view showing a schematic configuration of a third modification of the substrate  5  of the power control device  10  included in the electric motor  100  according to Embodiment 1 as viewed from the opposite stator side. 
     On the surface of the substrate  5  on the opposite stator side, the paths  16  through which heat is transferred are formed between the power semiconductor module  11  and the microcomputer  12 . As shown in  FIG.  8   , in the case where the substrate  5  has the through hole  5   a , thus having a toroidal shape, the first part  13  is not always necessary to be disposed on the straight line connecting the power semiconductor module  11  and the microcomputer  12 . In the same manner, the second part  15  is not always necessary to be disposed on the straight line connecting the power semiconductor module  11  and the microcomputer  12 . Further, a plurality of paths  16  through which heat is transferred may be formed, or only a single path  16  may be formed. 
       FIG.  9    is a schematic view showing a cross section of a schematic configuration of a first modification of the electric motor  100  according to Embodiment 1.  FIG.  10    is a schematic view showing a cross section of a schematic configuration of a second modification of the electric motor  100  according to Embodiment 1. 
     As shown in  FIG.  9    and  FIG.  10   , regarding the surface of the substrate  5  on which components are disposed, it is not always necessary to dispose the power semiconductor module  11 , the microcomputer  12 , the first part  13 , and the second part  15  on the same surface (on the stator side or the opposite stator side). In the case where the power semiconductor module  11  and the microcomputer  12  are respectively disposed on different surfaces of the substrate  5 , either the power semiconductor module  11  or the microcomputer  12  is assumed to be disposed at a plane symmetric position relative to the substrate  5 , and the position between the power semiconductor module  11  and the microcomputer  12  includes a position between the plane symmetric position of one of the power semiconductor module  11  and the microcomputer  12  and the other of the power semiconductor module  11  and the microcomputer  12 . For example, in the case where the power semiconductor module  11  is disposed on the surface of the substrate  5  on the stator side and the microcomputer  12  is disposed on the surface of the substrate  5  on the opposite stator side, the position between the power semiconductor module  11  and the microcomputer  12  means a position between the plane symmetric position of the power semiconductor module  11  relative to the substrate  5  and the microcomputer  12  on the surface of the substrate  5  on the opposite stator side and a position between the power semiconductor module  11  and the plane symmetric position of the microcomputer  12  relative to the substrate  5  on the surface of the substrate  5  on the stator side. The same applies for a position between the first part  13  having a low thermal conductivity and the power semiconductor module  11 . 
     As described above, the power control device  10  according to Embodiment 1 is the power control device  10  that drives the electric motor  100  including the rotor  2  and the stator  3 , the rotary shaft  1  being inserted into the rotor  2 , the stator  3  being provided on the outer peripheral side of the rotor  2 . The power control device  10  includes: the annular substrate  5  having the through hole  5   a  and disposed to face the rotor  2  and the stator  3 , the rotary shaft  1  being caused to pass through the through hole  5   a ; the power semiconductor module  11  mounted on the substrate  5  and including the drive circuit  110 ; and the microcomputer  12  mounted on the substrate  5  and configured to control power supplied to the electric motor  100 . The substrate  5  is integrally formed with the stator  3  by using the molded resin  14 , and the first part  13  having a lower thermal conductivity than the molded resin  14  is disposed on the substrate  5  at a position between the power semiconductor module  11  and the microcomputer  12 . The substrate  5  has an annular shape in Embodiment 1, However, the shape of the substrate  5  is not limited to an annular shape, and the substrate  5  may have other shapes. 
     In the power control device  10  according to Embodiment 1, the first part  13  having a lower thermal conductivity than the molded resin  14  is disposed on the substrate  5  at a position between the power semiconductor module  11  and the microcomputer  12 . Therefore, thermal conductivity is reduced at the position between the power semiconductor module  11  and the microcomputer  12 , so that heat from the power semiconductor module  11  is prevented from being easily transferred to the microcomputer  12  and hence, it is possible to suppress an increase in temperature of the microcomputer  12 . As a result, it is possible to achieve a higher output and a further reduction in size of the electric motor  100  including the power control device  10 . 
     In the power control device  10  according to Embodiment 1, the second part  15  having a higher thermal conductivity than the molded resin  14  is disposed on the substrate  5  at the position between the power semiconductor module  11  and the first part  13  and close to the outer periphery or the inner periphery of the substrate  5 . 
     With the power control device  10  according to Embodiment 1, it is possible to cause heat from the power semiconductor module  11  to easily escape to the outside of the motor from the inner peripheral side or the outer peripheral side of the substrate  5  via the second part  15  having a high thermal conductivity. Therefore, the amount of heat transferred to the microcomputer  12  is reduced and hence, it is possible to suppress an increase in temperature of the microcomputer  12 . As a result, it is possible to achieve a higher output and a further reduction in size of the electric motor  100  including the power control device  10 . 
     In the power control device  10  according to Embodiment 1, the second part  15  having a higher thermal conductivity than the molded resin  14  is disposed on the surface of the substrate  5  on the opposite stator side at the position between the power semiconductor module  11  and the first part  13 , and the heat sink  18  is disposed on the opposite stator side at a position that faces the substrate  5 . 
     With the power control device  10  according to Embodiment 1, heat can easily escape through the path from the first part  13  having a low thermal conductivity to the heat sink  18 , so that heat is further prevented from being easily transferred to the microcomputer  12  and hence, it is also possible to further suppress an increase in temperature of the microcomputer  12 . 
     In the power control device  10  according to Embodiment 1, the microcomputer  12  is disposed on the surface of the substrate  5  on the opposite stator side. 
     In the power control device  10  according to Embodiment 1, the microcomputer  12  is disposed on the surface of the substrate  5  on the opposite stator side, so that heat from the winding  3   c  is prevented from being easily transferred and hence, it is possible to further suppress an increase in temperature of the microcomputer  12 . 
     Embodiment 2 
     Hereinafter, Embodiment 2 will be described. The same description as Embodiment 1 will be omitted, and components identical or corresponding to the components in Embodiment 1 are given the same reference symbols. 
       FIG.  11    is a schematic view showing a constitutional example of an air-conditioning apparatus  200  according to Embodiment 2. 
     As shown in  FIG.  11   , the air-conditioning apparatus  200  includes an indoor unit  210  and an outdoor unit  220 . The indoor unit  210  is connected with the outdoor unit  220  via a refrigerant pipe  230 . The indoor unit  210  includes an indoor unit fan (not shown in the drawing), and the outdoor unit  220  includes an outdoor unit fan  223 . 
     Each of the outdoor unit fan  223  and the indoor unit fan incorporates the electric motor  100  described in Embodiment 1 as a drive source. In Embodiment 2, each of the indoor unit  210  and the outdoor unit  220  includes the fan. However, the configuration is not limited to such a configuration. It is sufficient that at least one of the indoor unit  210  and the outdoor unit  220  include a fan. 
     The electric motor  100  may be mounted on and used for a ventilation fan, a household electrical appliance, or a machine tool, for example, aside from the air-conditioning apparatus  200 . When the maximum output of the motor increases (equal to or higher than 100 W; for example), a large amount of heat is generated from the power semiconductor module  11 , so that the large amount of heat is easily transferred also to the microcomputer  12 . Accordingly, in such a case, it is possible to obtain a larger effect of suppressing an increase in temperature of the microcomputer  12  described in Embodiment 1. 
     As described above, the maximum output of the electric motor  100  according to Embodiment 2 is equal to or higher than 100 \N. 
     In the air-conditioning apparatus  200  according to Embodiment 2; the maximum output of the motor is large, so that a large amount of heat is generated from the power semiconductor module  11 . Accordingly, it is possible to obtain a larger effect of suppressing an increase in temperature of the microcomputer  12  described in Embodiment 1. 
     The air-conditioning apparatus  200  according to Embodiment 2 includes the indoor unit  210  and the outdoor unit  220 , at least one of the indoor unit  210  and the outdoor unit  220  includes the fan, and the electric motor  100  is provided as a power source for the fan. 
     The air-conditioning apparatus  200  according to Embodiment 2 can obtain advantageous effects substantially equal to the advantageous effects of the power control device  10  described in Embodiment 1. 
     REFERENCE SIGNS LIST 
       1 : rotary shaft,  2 : rotor;  2   a : rotor body;  2   b : rotor magnet,  2   c : sensor magnet,  3 : stator,  3   a : stator core,  3   b : insulator,  3   c : winding,  4   a : output-side bearing,  4   b : opposite-output-side bearing,  5 : substrate,  5   a : through hole,  6 : lead wire,  10 : power control device,  11 : power semiconductor module,  11 R: overcurrent detecting resistor,  11   x : power transistor,  11   x   1  to  11   x   6 : power transistor,  11   y : gate drive circuit,  11   z : protection circuit,  12 : microcomputer,  13 : first part,  14 : molded resin,  15 : second part,  16 : path through which heat is transferred,  17 : lead-out portion,  18 : heat sink,  19 : magnetic sensor,  30 : molded stator,  31 : conductive bracket,  50 : substrate,  100 : electric motor,  100   a  motor body,  110 : drive circuit,  200 : air-conditioning apparatus,  210 : indoor unit,  220 : outdoor unit,  223 : outdoor unit fan,  230 : refrigerant pipe.