Patent Publication Number: US-2023155456-A1

Title: Inverter integrated motor

Description:
TECHNICAL FIELD 
     The present invention relates to an inverter integrated motor. 
     BACKGROUND ART 
     In an inverter integrated motor in which a motor and an inverter are integrated, there is an increasing demand for further reduction in size and height in order to increase a vehicle interior space and a cruising distance of an electric vehicle (EV). At that time, since downsizing of a device increases a heat generation density, cooling of inverter components having low heat resistance is required. Further, in the reduction in height of the device, there is a problem in terms of motor mountability of the inverter, and a structure in which the inverter is disposed with less unevenness with respect to the motor which is being downsized is required. 
     As a background art of the present invention, the following PTL 1 is known. PTL 1 discloses an electric circuit device in which a current sensor  304  is embedded in an intermediate member  3  of a rotary electric machine  1 , thereby making it possible to suppress an increase in the overall size. 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP 2011-250645 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     In a technique of PTL 1, there is no cooling mechanism of the current sensor  304 , and when the current sensor is housed in a motor housing, a sensing error occurs in the current sensor  304  and a problem of poor reliability occurs. In view of this, an object of the present invention is to realize downsizing of an inverter integrated motor while considering cooling of a current sensor. 
     Solution to Problem 
     An inverter integrated motor according to the present invention includes: a power module that converts a direct current into an alternating current; a flow path forming body configured to cause a refrigerant to flow through the power module and cover the power module; an inverter in which the power module and the flow path forming body are installed; a current sensor that detects the alternating current; a motor including a stator and a rotor; and a motor housing that houses the stator and the rotor, wherein the power module is disposed at a position facing a rotation shaft of the motor via the stator and the rotor, and the current sensor is disposed between the flow path forming body and a coil end of the stator when viewed from a direction perpendicular to the rotation shaft, and at least a part of the current sensor is housed in the motor housing. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to provide an inverter integrated motor that achieves both improvement in cooling performance of a current sensor and downsizing of the entire device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an overall perspective view of an inverter integrated motor according to an embodiment of the present invention. 
         FIG.  2    is an exploded view of  FIG.  1   . 
         FIG.  3    is a diagram for explaining an internal structure of a conventional inverter. 
         FIG.  4    is a diagram for explaining an internal structure of an inverter of the present invention. 
         FIG.  5    is a cross-sectional view taken along line B-B of  FIG.  1   . 
         FIG.  6    is a cross-sectional view taken along line A-A of  FIG.  1   . 
         FIG.  7    is a diagram for explaining a joint part between an inverter and a motor in  FIG.  6   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each of the embodiments is an example for describing the present invention, and omission and simplification are appropriately made for clarity of description. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. Further, the position, size, shape, range, and the like of each component illustrated in the drawings may not represent the actual position, size, shape, range, and the like in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, and the like disclosed in the drawings. 
     (Configuration of inverter integrated motor)  FIG.  1    is an overall perspective view of an inverter integrated motor according to an embodiment of the present invention. Note that the B-B disconnection is used in the description of  FIG.  5   , and the A-A disconnection is used in the description of  FIG.  6   . 
     An inverter integrated motor  100  includes a motor  1 , an inverter  2 , and a gear box  3 . 
     The inverter integrated motor  100  has a mechanism in which a rotation shaft of the motor  1  and a shaft on a side of an input of the gear box  3  are mechanically connected to each other, a rotation speed of the motor  1  is reduced, and torque is transmitted from a shaft on a side of an output of the gear box  3  to an axle of a vehicle. Note that a reduction ratio at this time is determined by the number of teeth of a plurality of gears incorporated in the gear box  3 , and generally takes a value of about 8 to 18. 
       FIG.  2    is an exploded view of the inverter integrated motor  100  of  FIG.  1   . 
     A motor flow path inlet  6  and a motor flow path outlet  7  are formed on a surface of a motor housing  8 . The motor flow path inlet  6  and the motor flow path outlet  7  serve as inlets and outlets for a refrigerant flowing into the motor housing  8 . 
     The inverter  2  is fastened to be in contact with an inverter mounting surface  24  of the motor  1  by an assembling fixing part  5  provided in the motor housing  8 . Similarly, the gear box  3  is also fastened to the motor  1  by the assembling fixing part  5  provided in the motor housing  8 . A heat generated in the inverter  2  is dissipated to the refrigerant flowing inside the motor  1  by this fastening. 
     The motor housing  8  includes a current sensor housing part  4  for housing a current sensor  13  (described later) attached to an inverter enclosure  23  when the inverter  2  and the motor  1  are integrated. Details will be described later. 
       FIG.  3    is a diagram for explaining an internal structure of a conventional inverter  2 A. 
     The inverter  2 A includes a power module  14  (described later) in which a power semiconductor switch such as an IGBT or a diode for converting DC power into AC power is mounted and incorporated, a flow path forming body  12  for causing a refrigerant to flow through the power module  14  and cooling the power module, a capacitor  19  for smoothing a DC ripple voltage generated in a DC voltage at the time of power conversion, a current sensor  13 A for detecting an AC current, AC bus bars  15 A, a control board, and an EMC filter (unsigned). These constituent components of the inverter  2 A are incorporated in an inverter enclosure  23 A to form a main circuit of a three-phase inverter. Note that the flow path forming body  12  is formed so as to cover the power module  14 . 
     The inverter  2 A includes the AC bus bars  15 A for three phases in order to electrically connect the capacitor  19  and the power module  14  to the motor  1  described above, and the AC bus bars  15 A are output from the inverter enclosure  23 A to the outside. Each of the three-phase AC bus bars  15 A includes a current sensor  13 A. Note that a DC connector (unsigned) is also output from the inverter enclosure  23 A in addition to the AC bus bars  15 A. 
     In order to perform vector control, the current sensor  13 A detects three-phase AC current values of the motor  1  and feeds them back to a motor controller (not illustrated). Further, since the current sensor  13 A has a threshold of a predetermined heat-resistant allowable temperature, when the current sensor  13 A operates in a high temperature environment exceeding the threshold of the temperature, a detection error occurs. Note that the predetermined heat-resistant allowable temperature is, for example, 125° C. 
       FIG.  4    is a diagram for explaining an internal structure of the inverter  2  according to an embodiment of the present invention. 
     Current sensors  13  are formed so as to surround AC bus bars  15  in a circumferential direction, and an insulating resin is provided between each of the current sensors and each of the AC bus bars  15 . As a result, each of the current sensors  13  is non-contact current sensor  13  that is not in contact with each of the AC bus bars  15 . 
     In the inverter  2 , as compared with the conventional inverter  2 A, each of the AC bus bars  15  does not extend along the inverter  2 , but extends in a direction of the motor  1 , which is a lower direction (back side in the drawing) of the inverter  2 . Therefore, a volume of the inverter enclosure  23  is smaller than that of the conventional inverter enclosure  23 A by an amount that each of the AC bus bars  15  does not extend. 
     Further, along with this, each of the current sensors  13  can also be installed between the inverter  2  and the motor  1  in accordance with an extending direction of the AC bus bars  15  without being installed on an upper part (a front side in the drawing) of the flow path forming body  12 . More specifically, each of the current sensors  13  is installed on an opposite surface of the inverter enclosure  23  via an installation surface of the flow path forming body  12 . Therefore, downsizing and height reduction of the inverter  2  can be realized. 
       FIG.  5    is a cross-sectional view of the inverter integrated motor  100  of  FIG.  1    taken along line B-B. 
     The motor  1  has a configuration in which a rotor  10  and a stator (stator core)  17  are housed in the motor housing  8 . The rotor  10  has a rotation shaft  11 , and is connected to a shaft on the side of the input of the gear box  3  to transmit torque. The rotor  10  rotates inside the stator core  17 , and power is supplied to the motor  1  by a coil formed around the stator core  17  in an axial direction. 
     A coil end  9 , which is an end part of the coil, is formed in the coil formed in the stator core  17 . A motor cable  16  for connection with the inverter  2  is output from the coil end  9 . 
     The current sensor housing part  4  is provided in the motor housing  8  by using a space excluding the rotor  10 , the stator  17 , and the rotation shaft  11 . When the inverter  2  is coupled to the motor  1 , the inverter  2  is fixed such that an attachment part of the current sensor  13  is fitted into the current sensor housing part  4  provided in the motor  1 . As a result, the current sensor housing part  4  houses the current sensor  13  in the motor housing  8  of the motor  1 . 
     Here, since the current sensor  13  needs to be cooled by the flow path forming body  12  of the power module  14 , the current sensor is disposed at a position sandwiched between the coil end  9  and the flow path forming body  12  in the motor housing  8 . As a result, at least a part of the current sensor  13  is housed in the motor housing  8 , high density mounting is achieved, and the fixability can be also enhanced. 
     The power module  14  and the flow path forming body  12  have a positional relationship facing the motor rotation shaft  11  with the current sensor  13  interposed therebetween. As a result, a length of a wiring of the AC bus bar  15 , which is an alternating-current wiring between the motor  1  and the inverter  2 , is shortened. This achieves downsizing and height reduction of the inverter integrated motor  100 . 
     In summary, the power module  14  is disposed at a position facing the rotation shaft  11  of the motor  1  via the stator  17  and the rotor  10 . Further, the current sensor  13  is disposed between the flow path forming body  12  and the coil end  9  of the stator  17  when viewed from a direction perpendicular to the rotation shaft  11 . As a result, at least a part of the current sensor  13  is housed in the motor housing  8 . 
     The flow path of the motor  1  will be described. The motor  1  causes a refrigerant for cooling the entire device to flow from the motor flow path inlet  6  described above, and causes the refrigerant to flow to the flow path forming body  12  and a motor flow path  18 , which are continuous flow paths. That is, the refrigerant flowing in the motor flow path  18  also flows to the flow path forming body  12  for cooling the power module  14  built in the inverter  2 , and the refrigerant is shared by the motor  1  and the inverter  2 . The refrigerant that has flowed through the flow path forming body  12  and the motor flow path  18  is discharged from the motor flow path outlet  7  described above to the outside of the inverter integrated motor  100 . Such a refrigerant circulation structure enables cooling of the motor  1  and the inverter  2 . 
     The flow path forming body  12  that cools the power module  14  can cool the current sensor  13  and an air layer in a space around the current sensor  13 . Therefore, even when the inside of the motor housing  8  is in a high-temperature environment higher than or equal to the heat-resistant temperature of the current sensor  13 , the disposed current sensor  13  is cooled by the refrigerant flowing in the motor flow path  18 , and the temperature of the current sensor  13  can be maintained at a temperature lower than a predetermined allowable heat-resistant temperature. This makes it possible to reduce a detection error of the current sensor  13  and improve reliability. Note that the temperature of the refrigerant is, for example, 70° C. or lower. 
     Further, with the above configuration, a capacitor  19  disposed in the inverter  2  is also indirectly cooled from the motor housing  8  via the inverter enclosure  23  in addition to a cooling effect from the flow path forming body  12 , thereby improving the cooling performance. Thus, the inverter integrated motor  100  can operate with high accuracy and high reliability. 
     This eliminates the need for the inverter  2  to extend the inverter enclosure  23  to dispose the current sensor  13  and the AC bus bar  15 . Further, since an inner wall of the current sensor housing part  4  is close to the flow path forming body  12  of the inverter  2  and the motor flow path  18 , the current sensor housing part  4  has a structure capable of performing heat transfer with respect to the surrounding inner wall. Therefore, it is possible to realize the inverter integrated motor  100  with improved cooling performance as well as downsizing of the inverter  2 . 
       FIG.  6    is a cross-sectional view of the inverter integrated motor  100  of  FIG.  1    taken along line A-A. 
     The AC bus bar  15  penetrates the current sensor  13  in which a hole is formed at a center part, and the penetrating part is made of an insulating resin. As a result, the current sensor  13  is a non-contact sensor. Further, when the inverter  2  and the motor  1  are integrated, the AC bus bar  15  is connected to the motor cable  16  of the motor  1  when the current sensor  13  is housed in the current sensor housing part  4 . As a result, the current sensor housing part  4  improves the positioning of the current sensor  13  and the AC bus bar  15 . 
     At this time, the motor flow path  18  and a flow path of the flow path forming body  12  are also connected, and the refrigerant flowing inside the respective flow paths is shared as described above. As a result, the thermal resistance between the current sensor  13  and the flow path forming body  12  can be reduced. 
     With such a configuration, a connection wiring length constituted by the AC bus bar  15  of the inverter  2  and the motor cable  16  can be significantly shortened, and a volume of the inverter  2  can also be reduced. Further, the current sensor  13  is cooled not only by a surface of the flow path forming body  12  but also by the motor flow path  18 , and can be operated with high accuracy and high reliability even inside the motor housing  8  in a high-temperature environment, and sensing accuracy and reliability can be secured. 
       FIG.  7    is a diagram for explaining a joint part between the inverter  2  and the motor  1  in  FIG.  4   . 
     In the current sensor  13 , three-phase currents corresponding to the AC bus bar  15  are attached to the current sensor attachment part  20 , and at least a part of the current sensor  13  is in contact with and fixed to a current sensor cooling surface  21 . As a result, the current sensor  13  is cooled by the flow path forming body  12 , and the temperature of the current sensor  13  can be maintained at a predetermined allowable temperature or less. 
     The current sensor attachment part  20  is provided on a surface of the inverter enclosure  23  opposite to the flow path forming body  12 , and attaches the current sensor  13 . Further, the current sensor attachment part  20  is sealed by a lid body  22  in order to enhance the fixability of the current sensor. 
     The AC bus bar  15  connected to the power module penetrates the lid body  22 , and the AC bus bar  15  is connected to the motor. Further, as described above, when the inverter  2  and the motor  1  are integrated, the current sensor attachment part  20  is fitted with the housing part  4  formed in the motor housing  8  for housing the current sensor  13 . 
     With such a configuration, the current sensor  13  is thermally protected from a high-temperature environment inside the motor  1  and the oil of the gears in the gear box  3 . Note that the current sensor  13  may be a coreless sensor. In that case, it is necessary to cool a sense IC and a shield member. The coreless sensor is also basically a non-contact sensor, and is disposed in cooperation with the AC bus bar  15  of the inverter  2 . 
     According to the first embodiment of the present invention described above, the following operational effects are achieved. 
     (1) An inverter integrated motor  100  includes: a power module  14  that converts a direct current into an alternating current; a flow path forming body  12  configured to cause a refrigerant to flow through the power module  14  and cover the power module  14 ; an inverter  2  in which the power module  14  and the flow path forming body  12  are installed; a current sensor  13  that detects the alternating current; and a motor  1  including a motor housing  8  that houses a stator  17  and a rotor  10 . The power module  14  is disposed at a position facing a rotation shaft  11  of the motor  1  via the stator  17  and the rotor  10 . The current sensor  13  is disposed between the flow path forming body  12  and a coil end  9  of the stator  17  when viewed from a direction perpendicular to the rotation shaft  11 , and at least a part of the current sensor  13  is housed in the motor housing  8 . With this configuration, it is possible to provide the inverter integrated motor  100  that achieves both cooling performance and downsizing of the inverter  2 . 
     (2) The current sensor  13  of the inverter integrated motor  100  is installed on an opposite surface of an enclosure  23  of the inverter  2  via an installation surface of the flow path forming body  12 . Thus, the inverter  2  is downsized. 
     (3) The current sensor  13  of the inverter integrated motor  100  is installed in an attachment part  20  formed in the enclosure  23  of the inverter  2  for attaching the current sensor  13 , and the attachment part  20  is fitted with a housing part  4  formed in the motor housing  8  for housing the current sensor when the inverter  2  and the motor  1  are integrated. This configuration contributes to downsizing of the inverter integrated motor  100  while improving the fixability of the current sensor  13 . 
     (4) In the inverter integrated motor  100 , the attachment part  20  is sealed by a lid body  22 , and an AC bus bar  15  connected to the power module  14  penetrates the lid body  22  and is connected to the motor  1 . With this configuration, the fixability of the current sensor  13  is enhanced. 
     (5) In the inverter integrated motor  100 , the current sensor  13  is not in contact with the AC bus bar  15 . With this configuration, it is possible to reduce the space required for disposing the current sensor  13  while adopting the non-contact type. 
     (6) In the inverter integrated motor  100 , the current sensor  13  is a coreless current sensor. With this configuration, even if another type of current sensor is adopted, a similar effect can be obtained. 
     Note that the above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the matters described in the above embodiment and the matters described in the claims. Further, deletion, replacement with another configuration, and addition of another configuration can be performed without departing from the technical idea of the invention, and an aspect thereof is also included in the scope of the present invention. 
     REFERENCE SIGNS LIST 
     
         
           100  inverter integrated motor 
           1  motor 
           2  inverter 
           3  gear box 
           4  current sensor housing part 
           5  fixing part 
           6  motor flow path inlet 
           7  motor flow path outlet 
           8  motor housing 
           9  coil end 
           10  rotor 
           11  rotation shaft 
           12  flow path forming body 
           13 ,  13 A current sensor 
           14  power module 
           15 ,  15 A AC (alternating current) bus bar 
           16  motor cable 
           17  stator (stator core) 
           18  motor flow path 
           19  capacitor 
           20  current sensor attachment part 
           21  current sensor cooling surface 
           22  lid body of current sensor housing part 
           23 ,  23 A inverter enclosure 
           24  inverter mounting surface claims