Vehicle drive unit

Abstract

To increase a motor output while suppressing increase in size of a drive unit consisting of a motor and an inverter, and to reduce and level inductance of a path from a power module to a coil.SOLUTION: In a drive unit, a motor, and an inverter having a plurality of power modules are adjacent to each other in a motor axial direction. In the motor, a first coil group and a second coil group each including one U-phase coil, one V-phase coil, and one W-phase coil are configured. The plurality power modules configure a first power module group and a second power module group connected in parallel. Each of the first and second power module groups includes one U-phase power module, one V-phase power module, and one W-phase power module. A distance between the U-phase power module of the first power module group and the U-phase coil of the first coil group, a distance between the V-phase power module of the first power module group and the V-phase coil of the first coil group, and a distance between the W-phase power module of the first power module group and the W-phase coil of the first coil group, are the same as each other when seen from an axial direction.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a drive unit for a vehicle including a motor and an inverter.

Background Art

[0002] A drive unit that converts a direct current from a battery into an alternating current by an inverter to drive a motor is known. The inverter has a power module including switching elements. The inverter disclosed in Patent Document 1 includes a power module unit including a U-phase power module, a V-phase power module, and a W-phase power module. Each phase power module corresponds to each phase coil of the motor.

[0003] Since this type of inverter handles large power, a high voltage is applied and a large current flows. Therefore, the amount of heat generated during operation is large and cooling is required. A large surge voltage also occurs. Therefore, individual electronic components constituting the inverter tend to be large and heavy. Therefore, the conventional inverter is a factor that hinders improvement in fuel efficiency and electricity cost.

[0004] In addition, in order to shorten the power transmission distance, the inverter is usually arranged near the drive motor. However, in the case of an automobile, there are many devices to be installed, and the space where the inverter can be arranged is limited. It is also necessary to consider the balance of the vehicle body. Therefore, it is difficult to appropriately arrange a large and heavy inverter in an automobile.

[0005] In response to such problems, in Patent Document 1, the inverter is integrated with the motor to reduce the size and weight of the inverter.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Each phase power module of the inverter is connected to each phase coil of the motor via an electrical connection member. Since a large current flows through the electrical connection member, the electrical connection member is large-sized and heavy. When the wiring length of the electrical connection member becomes long, the electrical resistance increases accordingly, and copper loss occurs during energization. The electrical connection member also generates a large amount of heat. Moreover, in the inverter, a large current is switched on and off at high speed by switching control, and accordingly, a large magnetic change occurs in the electrical connection member.

[0008] As a result, during the operation of the inverter, noise, vibration, electromagnetic interference, etc. are generated in the electrical connection member due to the magnetic change. Noise, vibration, electromagnetic interference, etc. not only result in energy loss but also have various adverse effects on the performance of the automobile, so countermeasures are necessary.

[0009] Therefore, from the perspective of motor control, it is important to reduce the inductance of the electrical path from each phase power module to each phase coil of the motor and equalize it among the U-phase, V-phase, and W-phase. In particular, when the output of the motor is large, it becomes more important to reduce and equalize the inductance of the above electrical path.

[0010] On the other hand, in order to increase the output of the motor, it is necessary to increase the number of power modules in the inverter. However, it is desirable to avoid the increase in size of the inverter accompanying the increase in the number of power modules.

[0011] The present disclosure has been made in view of such points, and the object thereof is to increase the motor output while suppressing the increase in size of the drive unit composed of the motor and the inverter, and to reduce and equalize the inductance of the electrical path from each phase power module to each phase coil.

Means for Solving the Problems

[0012] The drive unit of a vehicle according to a first aspect of the present disclosure is a drive unit of a vehicle in which a motor and an inverter having a plurality of power modules are arranged adjacent to each other in the axial direction of the motor. Each of the power modules is placed on a mounting surface orthogonal to the axial direction. In the motor, at least a first coil group and a second coil group are configured as a coil group including one U-phase coil, one V-phase coil, and one W-phase coil each. The plurality of power modules constitute at least a first power module group and a second power module group connected in parallel with each other. The first power module group and the second power module group each include one U-phase power module, one V-phase power module, and one W-phase power module corresponding to the U-phase coil, the V-phase coil, and the W-phase coil, respectively. Each power module in the first power module group is connected to each coil in the first coil group, and each power module in the second power module group is connected to each coil in the second coil group. The distance between the U-phase power module in the first power module group and the U-phase coil in the first coil group, the distance between the V-phase power module in the first power module group and the V-phase coil in the first coil group, and the distance between the W-phase power module in the first power module group and the W-phase coil in the first coil group are equal to each other when viewed in the axial direction.

[0013] According to such a configuration, since the first power module group and the second power module group are connected in parallel with each other in the inverter, the output of the motor can be increased.

[0014] In addition, since each power module is arranged side by side on a mounting surface orthogonal to the motor axial direction, an increase in the axial length of the inverter can be suppressed even though the number of power modules is increased.

[0015] In addition, since the motor and the inverter are arranged adjacent to each other in the motor axis direction, the distance between each phase power module and each phase coil can be shortened. Therefore, the inductance of the electrical path from each phase power module to each phase coil can be reduced.

[0016] Furthermore, in the first power module group and the first coil group, the distances between each phase power module and each phase coil are equal to each other when viewed in the motor axis direction among the U-phase, V-phase, and W-phase. Therefore, in the first power module group and the first coil group, the inductance of the electrical path from each phase power module to each phase coil can be equalized among the U-phase, V-phase, and W-phase.

[0017] As described above, while suppressing the increase in size of the drive unit composed of the motor and the inverter, the motor output can be increased, and the inductance of the electrical path from each phase power module to each phase coil can be reduced and equalized.

[0018] In one embodiment, the distance between the U-phase power module of the second power module group and the U-phase coil of the second coil group, the distance between the V-phase power module of the second power module group and the V-phase coil of the second coil group, and the distance between the W-phase power module of the second power module group and the W-phase coil of the second coil group are equal to each other when viewed in the axial direction.

[0019] According to such a configuration, also in the second power module group and the second coil group, similar to the first power module group and the first coil group, the inductance of the electrical path from each phase power module to each phase coil can be equalized among the U-phase, V-phase, and W-phase.

[0020] In one embodiment, the distance between the U-phase power module of the first power module group and the U-phase coil of the first coil group, and the distance between the U-phase power module of the second power module group and the U-phase coil of the second coil group are equal to each other when viewed in the axial direction. The distance between the V-phase power module of the first power module group and the V-phase coil of the first coil group, and the distance between the V-phase power module of the second power module group and the V-phase coil of the second coil group are equal to each other when viewed in the axial direction. The distance between the W-phase power module of the first power module group and the W-phase coil of the first coil group, and the distance between the W-phase power module of the second power module group and the W-phase coil of the second coil group are equal to each other when viewed in the axial direction.

[0021] According to such a configuration, between the first power module group and the first coil group, and between the second power module group and the second coil group, the inductance of the electrical path from each phase power module to each phase coil can be equalized.

[0022] In one embodiment, in the motor, each of the U-phase coil, the V-phase coil, and the W-phase coil is wound in a concentrated manner so as to be arranged at at least two positions. The U-phase power module of the first power module group is arranged at a position overlapping the U-phase coil of the first coil group when viewed in the axial direction. The V-phase power module of the first power module group is arranged at a position overlapping the V-phase coil of the first coil group when viewed in the axial direction. The W-phase power module of the first power module group is arranged at a position overlapping the W-phase coil of the first coil group when viewed in the axial direction.

[0023] According to such a configuration, in the first power module group and the first coil group, the distance between each phase power module and each phase coil can be made shorter. Therefore, in the first power module group and the first coil group, the inductance of the electrical path from each phase power module to each phase coil can be further reduced.

[0024] In one embodiment, the U-phase power module of the second power module group is arranged at a position overlapping the U-phase coil of the second coil group when viewed in the axial direction, the V-phase power module of the second power module group is arranged at a position overlapping the V-phase coil of the second coil group when viewed in the axial direction, and the W-phase power module of the second power module group is arranged at a position overlapping the W-phase coil of the second coil group when viewed in the axial direction.

[0025] According to such a configuration, also in the second power module group and the second coil group, similarly to the first power module group and the first coil group, the inductance of the electrical path from each phase power module to each phase coil can be further reduced.

[0026] In one embodiment, each power module of the first power module group is arranged on one side in the radial direction of the motor, each power module of the second power module group is arranged on the other side in the radial direction, the U-phase power module of the first power module group and the U-phase power module of the second power module group face each other in the radial direction, the V-phase power module of the first power module group and the V-phase power module of the second power module group face each other in the radial direction, and the W-phase power module of the first power module group and the W-phase power module of the second power module group face each other in the radial direction.

[0027] In a motor (especially a concentrated winding with an even number of turns), the coils of the same phase are often arranged to face each other in the radial direction of the motor. According to such a configuration, the power modules of the same phase are arranged to face each other in the radial direction of the motor, similarly to the coils of the same phase. This makes it easier to align each phase power module with each phase coil.

[0028] In one embodiment, at least an output bus bar is interposed between each of the power modules and each of the coils, and the output bus bar is configured to be wide so as to extend along the circumferential direction of the motor.

[0029] According to such a configuration, it is easy to make the output bus bar wide, and thus it is easy to reduce the inductance of the output bus bar.

[0030] In one embodiment, the inverter has a smoothing capacitor mounted on the mounting surface.

[0031] According to such a configuration, it is more advantageous in suppressing an increase in the axial length of the inverter.

[0032] In one embodiment, the smoothing capacitor and each of the power modules are connected to each other by a negative-side bus bar and a positive-side bus bar as input bus bars. One end of the input bus bar is connected to the smoothing capacitor, and the other end of the input bus bar is connected to each of the power modules. The inductance of the input bus bar is a function of the length from the one end to the other end in the input bus bar, and the function has a minimum value such that the same inductance is obtained at different first and second lengths. The length of one of the negative-side bus bar and the positive-side bus bar is the first length, and the length of the other of the negative-side bus bar and the positive-side bus bar is the second length.

[0033] According to such a configuration, in the input bus bar that connects the smoothing capacitor and each power module to each other, the inductance of the negative-side bus bar and the inductance of the positive-side bus bar can be equalized with each other, even though the length of the negative-side bus bar and the length of the positive-side bus bar are different from each other.

[0034] The drive unit of a vehicle according to a second aspect of the present disclosure is a drive unit of a vehicle in which a motor and an inverter having a plurality of power modules are arranged adjacent to each other in the axial direction of the motor. Each of the power modules is placed on a mounting surface orthogonal to the axial direction. In the motor, at least a first coil group and a second coil group are configured as a coil group including one U-phase coil, one V-phase coil, and one W-phase coil each. The plurality of power modules constitute at least a first power module group and a second power module group connected in parallel with each other. The first power module group and the second power module group each include one U-phase power module, one V-phase power module, and one W-phase power module corresponding to the U-phase coil, the V-phase coil, and the W-phase coil, respectively. Each power module of the first power module group is connected to each coil of the first coil group, and each power module of the second power module group is connected to each coil of the second coil group. The U-phase power module of the first power module group is arranged at a position overlapping the U-phase coil of the first coil group when viewed in the axial direction, the V-phase power module of the first power module group is arranged at a position overlapping the V-phase coil of the first coil group when viewed in the axial direction, and the W-phase power module of the first power module group is arranged at a position overlapping the W-phase coil of the first coil group when viewed in the axial direction.

[0035] According to such a configuration, since the first power module group and the second power module group are connected in parallel with each other in the inverter, the output of the motor can be increased.

[0036] Also, since each power module is arranged side by side on a mounting surface orthogonal to the motor axial direction, an increase in the axial length of the inverter can be suppressed even though the number of power modules is increased.

[0037] In addition, since the motor and the inverter are arranged adjacent to each other in the motor axis direction, the distance between each phase power module and each phase coil can be shortened. Therefore, the inductance of the electrical path from each phase power module to each phase coil can be reduced.

[0038] Furthermore, in the first power module group and the first coil group, each phase power module is arranged at a position overlapping each phase coil when viewed in the motor axis direction. Therefore, in the first power module group and the first coil group, the inductance of the electrical path from each phase power module to each phase coil can be equalized among the U-phase, V-phase, and W-phase.

[0039] As described above, while suppressing the increase in the size of the drive unit composed of the motor and the inverter, the motor output can be increased, and the inductance of the electrical path from each phase power module to each phase coil can be reduced and equalized.

[0040] In one embodiment, the U-phase power module of the second power module group is arranged at a position overlapping the U-phase coil of the second coil group when viewed in the axial direction, the V-phase power module of the second power module group is arranged at a position overlapping the V-phase coil of the second coil group when viewed in the axial direction, and the W-phase power module of the second power module group is arranged at a position overlapping the W-phase coil of the second coil group when viewed in the axial direction.

[0041] According to such a configuration, also in the second power module group and the second coil group, similar to the first power module group and the first coil group, the inductance of the electrical path from each phase power module to each phase coil can be equalized among the U-phase, V-phase, and W-phase.

Advantages of the Invention

[0042] According to the present disclosure, while suppressing the increase in size of a drive unit composed of a motor and an inverter, it is possible to increase the motor output and reduce and equalize the inductance of the electrical path from each phase power module to each phase coil.

Brief Description of the Drawings

[0043]

Figure 1

Figure 2

Figure 3

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Figure 5

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Figure 7

Figure 8

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Figure 11

Figure 12

Figure 13A

Figure 13B

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

MODE FOR CARRYING OUT THE INVENTION

[0044] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the present disclosure, its applications, or its uses.

[0045] <First Embodiment> (Vehicle Configuration) FIG. 1 shows a vehicle 1 including a drive unit A according to the first embodiment in a state as seen from below the vehicle. The vehicle 1 transmits power from at least one of an engine 2 and a drive motor 3 disposed on the front side of the vehicle to a rear wheel 4 disposed on the rear side of the vehicle. That is, the vehicle 1 is a front-engine rear-drive (FR) hybrid vehicle.

[0046] As shown in FIG. 1, the vehicle 1 includes an engine 2, a transmission 5 connected to the engine 2, a drive motor 3 disposed between the engine 2 and the transmission 5, a propeller shaft 6 connected to the transmission 5 for transmitting the power from the engine 2 and the drive motor 3 to the rear wheels, and a differential device 7 connected to the propeller shaft 6 for transmitting the power from the engine 2 and the drive motor 3 to the left and right rear wheels 4.

[0047] The propeller shaft 6 extends in the longitudinal direction of the vehicle below the floor panel 8. A tunnel portion 9 is provided on the center side in the vehicle width direction of the floor panel 8. The propeller shaft 6 is disposed inside the tunnel portion 9.

[0048] The vehicle 1 includes an exhaust pipe 10 extending in the longitudinal direction of the vehicle from the engine 2. A catalytic device 11 is disposed on the upstream side of the exhaust pipe 10. Although not shown, a silencer is disposed on the downstream side of the exhaust pipe 10.

[0049] The vehicle 1 includes a fuel tank (not shown) for storing fuel supplied to the engine 2 and a battery 12 for storing electric power supplied to the motor 3. The drive motor 3 transmits power to the rear wheels 4 and is rotationally driven by the propeller shaft 6 during vehicle deceleration to perform regenerative power generation, and supplies the generated electric power to the battery 12. The battery 12 is composed of a first battery unit 12a and a second battery unit 12b disposed on both sides in the vehicle width direction. The second battery unit 12b is longer in the longitudinal direction of the vehicle than the first battery unit 12a. Each battery unit 12a, 12b is composed of a plurality of battery cells. The battery cells are, for example, lithium ion batteries.

[0050] An in-wheel motor 14 is connected to each of the left and right front wheels 13. The in-wheel motor 14 functions as an assist motor that generates power and transmits it to the front wheels 13 when the vehicle 1 starts. The in-wheel motor 14 also functions as a regenerative brake that generates electricity during vehicle deceleration. The in-wheel motor 14 is supplied with electric power from the battery 12 in the same manner as the drive motor 3.

[0051] As shown in FIG. 1, an inverter 15 is interposed between a drive motor 3 and a transmission 5. The drive motor 3 and the inverter 15 are arranged adjacent to each other in the axial direction (vehicle longitudinal direction) of the drive motor 3. An inverter 16 is arranged inside the in-wheel motor 14 in the vehicle width direction. The in-wheel motor 14 and the inverter 16 are arranged adjacent to each other in the axial direction (vehicle width direction) of the in-wheel motor 14. The drive motor 3 and the inverter 15 constitute a drive unit A. Similarly, the in-wheel motor 14 and the inverter 16 constitute the drive unit A.

[0052] The inverters 15 and 16 convert the DC power stored in the battery 12 into AC power and supply it to the motors 3 and 14, and convert the AC power generated by the motors 3 and 14 during vehicle deceleration into DC power to charge the battery.

[0053] (Drive Unit) The drive unit A of the vehicle 1 will be described by taking the drive motor 3 and the inverter 15 as an example. FIG. 2 is a perspective view of the drive unit A. As described above, the drive unit A is composed of the motor 3 and the inverter 15. The motor 3 and the inverter 15 are coaxially arranged adjacent to each other in the axial direction of the motor 3. Specifically, the central axis O of the motor 3 and the central axis O of the inverter 15 coincide with each other. The motor 3 (specifically, the casing of the motor 3) is formed in a cylindrical shape. The inverter 15 (specifically, the casing of the inverter 15) is formed in a cylindrical shape corresponding to the motor 3. The rotating shaft 3a of the motor 3 penetrates the inverter 15 in the axial direction. The thickness Wiv of the inverter 15 is thin, for example, 50 mm or less (preferably 30 mm or less). A cooling passage 61 described later is provided inside the inverter 15. An inlet pipe 62 and an outlet pipe 63 for cooling, which communicate with the cooling passage 61, are connected to the upper part of the inverter.

[0054] FIG. 3 is a cross-sectional view of the motor 3 as seen from the inverter 15 side. The motor 3 has coils 17. Specifically, in the stator of the motor 3, each of the U-phase coil 17u, V-phase coil 17v, and W-phase coil 17w is concentrated wound so that two are arranged at two locations. Each coil 17 is arranged evenly in the circumferential direction of the motor 3.

[0055] As the U-phase coil 17u, there are a first U-phase coil 17u1 and a second U-phase coil 17u2. As the V-phase coil 17v, there are a first V-phase coil 17v1 and a second V-phase coil 17v2. As the W-phase coil 17w, there are a first W-phase coil 17w1 and a second W-phase coil 17w2.

[0056] In the motor 3, first coil group C1 and second coil group C2 are configured as coil groups each including one of the U-phase coil 17u, V-phase coil 17v, and W-phase coil 17w. Specifically, the first coil group C1 is composed of a first U-phase coil 17u1, a first V-phase coil 17v1, and a first W-phase coil 17w1. The second coil group C2 is composed of a second U-phase coil 17u2, a second V-phase coil 17v2, and a second W-phase coil 17w2.

[0057] Each phase coil 17u1, 17v1, 17w1 of the first coil group C1 is arranged on one side in the radial direction of the motor 3. Each phase coil 17u2, 17v2, 17w2 of the second coil group C2 is arranged on the other side in the radial direction of the motor 3.

[0058] The first U-phase coil 17u1 of the first coil group C1 and the second U-phase coil 17u2 of the second coil group C2 face each other in the radial direction of the motor 3. The first V-phase coil 17v1 of the first coil group C1 and the second V-phase coil 17v2 of the second coil group C2 face each other in the radial direction of the motor 3. The first W-phase coil 17w1 of the first coil group C1 and the second W-phase coil 17w2 of the second coil group C2 face each other in the radial direction of the motor 3.

[0059] Six motor-side terminal blocks 18 are provided on the outer peripheral portion of the motor 3. Each motor-side terminal block 18 corresponds to each coil 17. Specifically, each motor-side terminal block 18 is arranged at the same circumferential direction position and radially outside with respect to each coil 17. A lead wire (not shown) is drawn out from each coil 17. The lead wire is connected to each motor-side terminal block 18. On the rotating shaft 3a, a core 27 and permanent magnets 28 of N pole and S pole are fixed as a rotor.

[0060] Figure 4 is a circuit diagram of the inverter 15. The inverter 15 has a smoothing capacitor 19 and a plurality of power modules 20. The smoothing capacitor 19 smoothes the voltage applied to the power module 20. The plurality of power modules 20 constitute an inverter circuit and convert a DC voltage into an AC voltage.

[0061] As the plurality of power modules 20, there are a U-phase power module 20u, a V-phase power module 20v, and a W-phase power module 20w. The U-phase power module 20u corresponds to the U-phase coil 17u. The V-phase power module 20v corresponds to the V-phase coil 17v. The W-phase power module 20w corresponds to the W-phase coil 17w.

[0062] Furthermore, as the U-phase power module 20u, there are a first U-phase power module 20u1 and a second U-phase power module 20u2. As the V-phase power module 20v, there are a first V-phase power module 20v1 and a second V-phase power module 20v2. As the W-phase power module 20w, there are a first W-phase power module 20w1 and a second W-phase power module 20w2.

[0063] The plurality of power modules 20 constitute a first power module group P1 and a second power module group P2 that are connected in parallel to each other. The first power module group P1 and the second power module group P2 each include one U-phase power module 20u, one V-phase power module 20v, and one W-phase power module 20w.

[0064] The first power module group P1 is composed of a first U-phase power module 20u1, a first V-phase power module 20v1, and a first W-phase power module 20w1. Each phase power module 20u1, 20v1, 20w1 of the first power module group P1 is connected to each phase coil 17u1, 17v1, 17w1 of the first coil group C1. Specifically, the first U-phase power module 20u1 of the first power module group P1 is connected to the first U-phase coil 17u1 of the first coil group C1. The first V-phase power module 20v1 of the first power module group P1 is connected to the first V-phase coil 17v1 of the first coil group C1. The first W-phase power module 20w1 of the first power module group P1 is connected to the first W-phase coil 17w1 of the first coil group C1.

[0065] The second power module group P2 is composed of a second U-phase power module 20u2, a second V-phase power module 20v2, and a second W-phase power module 20w2. Each phase power module 20u2, 20v2, 20w2 of the second power module group P2 is connected to each phase coil 17u2, 17v2, 17w2 of the second coil group C2. Specifically, the second U-phase power module 20u2 of the second power module group P2 is connected to the second U-phase coil 17u2 of the second coil group C2. The second V-phase power module 20v2 of the second power module group P2 is connected to the second V-phase coil 17v2 of the second coil group C2. The second W-phase power module 20w2 of the second power module group P2 is connected to the second W-phase coil 17w2 of the second coil group C2.

[0066] The power module 20 is composed of two elements, a lower arm element 21 and an upper arm element 22 as switching elements. In each phase of the power module 20, when one of the lower arm element 21 and the upper arm element 22 is open, the other of the lower arm element 21 and the upper arm element 22 is closed. Thereby, a three-phase alternating current is supplied to the motor 3.

[0067] Here, the power module 20 includes a SiC-MOSFET. FIG. 5 shows a comparison between the SiC-MOSFET and the IGBT. The SiC-MOSFET is a MOSFET (metal-oxide-semiconductor field-effect transistor) including silicon carbide (SiC), and constitutes a chip 24 including a lower arm element 21, an upper arm element 22, and other control elements. The lower surface of the chip 24 is fixed to a silicon substrate by solder. A copper block 25 as a heat transfer block is fixed to the upper surface of the chip 24 by solder. The same applies to the IGBT (Insulated Gate Bipolar Transistor).

[0068] As shown in FIG. 5, the surface area of the chip 24 composed of the SiC-MOSFET is smaller than the surface area of the chip 24' composed of the IGBT. Accordingly, the size of the copper block 25 disposed above the SiC-MOSFET (chip) 24 is smaller than the size of the copper block 25' disposed above the IGBT (chip) 24'. Also, the SiC-MOSFET has better heat resistance than the IGBT.

[0069] FIG. 6 shows the detailed structure of the power module 20 in a perspective view and a circuit diagram. Each power module 20 has a wide and flat shape. Specifically, each power module 20 is longer in the width direction W than in the thickness direction t. The power module 20 has a substantially rectangular parallelepiped shape. The width direction W includes a first width direction W1 and a second width direction W2 that are orthogonal to each other. Hereinafter, one side in the thickness direction of the power module 20 may be referred to as the lower side, and the other side in the thickness direction may be referred to as the upper side.

[0070] The power module 20 has a lower surface 31 on the lower side (one-sided, one-sided in the thickness direction). The power module 20 has an upper surface 32 on the upper side. The power module 20 has a first end face 33 on one side in the first width direction W1. The power module 20 has a second end face 34 on the other side in the first width direction W1.

[0071] On the lower side of the first end face 33 and on one side in the second width direction W2, a negative electrode side input terminal 35 is connected. On the upper side of the first end face 33 and on the other side in the second width direction W2, a positive electrode side input terminal 36 is connected. The negative electrode side input terminal 35 and the positive electrode side input terminal 36 are arranged at intervals in the vertical direction (thickness direction). An output terminal 37 is connected to the central portion of the second end face 34.

[0072] In the package (box body) of the power module 20, a lower arm element 21 and an upper arm element 22 are accommodated. The negative electrode side input terminal 35 is connected to the lower arm element 21. The positive electrode side input terminal 36 is connected to the upper arm element 22. The output terminal 37 is connected between the lower arm element 21 and the upper arm element 22.

[0073] FIG. 7 is a cross-sectional view of the inverter 15 as seen from the side opposite to the motor 3. FIG. 8 is a longitudinal sectional view of the inverter 15 taken along line VIII-VIII. As shown in FIG. 7, at the center of the inverter 15, a shaft through hole 40 for passing through the rotation shaft 3a of the motor 3 is provided. A cylindrical boss portion 41 is formed around the shaft through hole 40. The smoothing capacitor 19 is arranged at the center O of the inverter 15. The smoothing capacitor 19 is arranged along the boss portion 41. The smoothing capacitor 19 is formed in a hollow polygonal column shape having a shaft through hole for passing through the rotation shaft 3a.

[0074] Each power module 20 (the first U-phase power module 20u1, the first V-phase power module 20v1, the first W-phase power module 20w1, the second U-phase power module 20u2, the second V-phase power module 20v2, and the second W-phase power module 20w2) is arranged on the outer peripheral side of the smoothing capacitor 19. Each power module 20 is arranged side by side in the circumferential direction of the motor 3 on the outer peripheral side of the smoothing capacitor 19. Further, the input terminals 35, 36 (the first end face 33) and the output terminal 37 (the second end face 34) of each power module 20 face the circumferential direction of the motor 3 (the inverter 15). Each power module 20 is arranged such that the thickness direction t coincides with the axial direction of the motor 3. The smoothing capacitor 19 and each power module 20 are arranged in the space partitioned by the outer peripheral wall portion 42 and the boss portion 41 in the inverter 15.

[0075] Each phase power module 20u1, 20v1, 20w1 of the first power module group P1 is arranged on one side in the radial direction of the motor 3 (the inverter 15). Each phase power module 20u2, 20v2, 20w2 of the second power module group P2 is arranged on the other side in the radial direction of the motor 3.

[0076] The first U-phase power module 20u1 of the first power module group P1 and the second U-phase power module 20u2 of the second power module group P2 face each other in the radial direction of the motor 3 (the inverter 15). The first V-phase power module 20v1 of the first power module group P1 and the second V-phase power module 20v2 of the second power module group P2 face each other in the radial direction of the motor 3. The first W-phase power module 20w1 of the first power module group P1 and the second W-phase power module 20w2 of the second power module group P2 face each other in the radial direction of the motor 3.

[0077] As shown in FIGS. 7 and 8, a heat sink 60 is provided on the motor 3 side in the inverter 15. The heat sink 60 is mainly used for cooling each power module 20. The heat sink 60 is disposed between the outer peripheral wall portion 42 and the boss portion 41 in the inverter 15. The heat sink 60 has an upper wall portion 60a, an outer peripheral wall portion 60b, a lower wall portion 60c, and an inner peripheral wall portion 60d.

[0078] The upper surface 65 on the upper wall portion 60a of the heat sink 60 constitutes a mounting surface (hereinafter sometimes referred to as "mounting surface 65") orthogonal to the axial direction of the motor 3. The lower surface 31 of each power module 20 faces the motor 3 side. Specifically, the lower surfaces 31 of the respective power modules 20 are arranged side by side on the same mounting surface 65.

[0079] As shown in FIGS. 7 and 8, the smoothing capacitor 19 is formed by covering an assembly of a plurality of columnar capacitors 45 with flat plates from both sides in the thickness direction. The smoothing capacitor 19 has a lower surface 19a on the lower side (one-sided, one side in the thickness direction). The smoothing capacitor 19 has an upper surface 19b on the side opposite to the lower surface 19a. The lower surface 19a and the upper surface 19b of the smoothing capacitor 19 are formed of flat plates. The lower surface 19a of the smoothing capacitor 19 faces the motor 3 side. Specifically, the lower surface 19a of the smoothing capacitor 19 is mounted on the mounting surface 65.

[0080] As shown in FIGS. 7 and 8, the smoothing capacitor 19 and each power module 20 are connected to each other by a negative electrode side bus bar 51 and a positive electrode side bus bar 52 as input bus bars 50 (hereinafter sometimes simply referred to as "bus bar 50"). The negative electrode side bus bar 51 and the positive electrode side bus bar 52 are plate-shaped. Specifically, the negative electrode side bus bar 51 and the positive electrode side bus bar 52 are longer in the width direction W and the length direction L than in the thickness direction t.

[0081] As shown in Fig. 7, the negative electrode side bus bar 51 and the positive electrode side bus bar 52 are configured to be wide along the circumferential direction of the motor 3 (inverter 15). In other words, the negative electrode side bus bar 51 and the positive electrode side bus bar 52 are configured to be wide along the direction in which the power modules 20 are arranged. The width direction W of the negative electrode side bus bar 51 and the positive electrode side bus bar 52 extends (in an arc shape) in the circumferential direction of the motor 3. The negative electrode side bus bar 51 and the positive electrode side bus bar 52 are fan-shaped. The length direction L of the negative electrode side bus bar 51 and the positive electrode side bus bar 52 extends in the radial direction of the motor 3.

[0082] One end 51i of the negative electrode side bus bar 51 (input bus bar 50) is connected to the negative electrode terminal 19c provided on the lower surface 19a side of the smoothing capacitor 19. The other end 51o of the negative electrode side bus bar 51 (input bus bar 50) is connected to the negative electrode side input terminal 35 of each power module 20. One end 52i of the positive electrode side bus bar 52 (input bus bar 50) is connected to the positive electrode terminal 19d provided on the upper surface 19b side of the smoothing capacitor 19. The other end 52o of the positive electrode side bus bar 52 (input bus bar 50) is connected to the positive electrode side input terminal 36 of each power module 20.

[0083] The negative electrode side bus bar 51 has a lower surface 51a on the lower side (one-sided, one-sided in the thickness direction). The lower surface 51a of the negative electrode side bus bar 51 faces the motor 3 side. Specifically, the lower surface 51a of the negative electrode side bus bar 51 is placed on the placement surface 65.

[0084] As shown in Fig. 7, an output bus bar 54 is connected to the output terminal 37 of each power module 20. There are a total of six output bus bars 54 corresponding to each of the power modules 20u1, 20v1, 20w1, 20u2, 20v2, 20w2 (each coil 17u1, 17v1, 17w1, 17u2, 17v2, 17w2). The output bus bar 54 is interposed between each power module 20 and each coil 17. The output bus bar 54 is plate-shaped. In addition to the output bus bar 54, a wire harness or the like may be interposed between each power module 20 and each coil 17.

[0085] Six inverter-side terminal blocks 46 are provided on the outer periphery of the inverter 15. Each inverter-side terminal block 46 corresponds to each power module 20. Specifically, each inverter-side terminal block 46 is arranged at the same circumferential direction position and radially outside with respect to each power module 20.

[0086] The output bus bar 54 extends to the inverter-side terminal block 46. A conductive member (such as a bus bar or a wire harness) is interposed between the inverter-side terminal block 46 and the motor-side terminal block 18.

[0087] (Cooling passage) As shown in FIGS. 7 and 8, a cooling passage (cooling jacket) 61 is provided inside the heat sink 60. The cooling passage 61 is defined by an upper wall portion 60a, an outer peripheral wall portion 60b, a lower wall portion 60c, and an inner peripheral wall portion 60d. The cooling passage 61 is formed in a donut shape (annular, cylindrical) over the entire circumference as viewed in the axial direction of the motor 3 (inverter 15) (see FIG. 7). The rotation shaft 3a of the motor 3 penetrates inside the inner peripheral wall portion 60d. As described above, the upper surface of the upper wall portion 60a of the heat sink 60 is the mounting surface 65.

[0088] The cooling passage 61 is provided on the motor 3 side with respect to the mounting surface 65. A cooling medium H flows through the cooling passage 61. The cooling medium H is cooling water, cooling oil, or the like.

[0089] Also, a plurality of fins 64 are provided inside the heat sink 60 (cooling passage 61). The fins 64 extend downward from the upper wall portion 60a into the cooling passage 61. That is, the fins 64 are provided on the motor 3 side with respect to the mounting surface 65.

[0090] As shown in FIGS. 7 and 8, the cooling passage 61 faces the lower surface 31 of each power module 20, the lower surface 51a of the negative electrode side bus bar 51, and the lower surface 19a of the smoothing capacitor 19 as viewed in the axial direction of the motor 3 (inverter 15).

[0091] Similarly, when viewed in the axial direction of the motor 3, the fin 64 faces the lower surface 31 of each power module 20, the lower surface 51a of the negative bus bar 51, and the lower surface 19a of the smoothing capacitor 19.

[0092] As shown in FIG. 2, an inlet pipe 62 and an outlet pipe 63 are connected to the upper part of the outer periphery of the inverter 15. The inlet pipe 62 and the outlet pipe 63 communicate with the cooling passage 61. The cooling medium H introduced into the cooling passage 61 through the inlet pipe 62 flows through the cooling passage 61 and is then discharged to the outside through the outlet pipe 63.

[0093] (Inductance sensitivity of bus bar) FIG. 9 is a perspective view of the bus bar 50. FIG. 10 is a graph showing the relationship between the size and the inductance sensitivity of the bus bar 50. As a result of intensive research, the inventors of the present application have made the following discoveries regarding the relationship between the size and the inductance sensitivity of the bus bar 50.

[0094] As shown in FIGS. 9 and 10, the larger the width dimension W (mm) of the bus bar 50, the smaller the inductance sensitivity (nH) of the bus bar 50.

[0095] Basically, the larger the length dimension L (mm) of the bus bar 50, the larger the inductance sensitivity (nH) of the bus bar 50. However, as shown in the middle graph of FIG. 10, there is a minimum value (inflection point) M in the relationship between the length dimension L (mm) and the inductance sensitivity (nH) of the bus bar 50. Thus, the same inductance sensitivity (nH) may occur even though the length dimensions L are different. Specifically, the inductance sensitivity (nH) of the bus bar 50 (51, 52) is a function of the length dimension L (mm) from one end 51i, 52i (terminals 19c, 19d of the smoothing capacitor 19) to the other end 51o, 52o (input terminals 35, 36 of each power module 20) of the bus bar 50 (51, 52). The function has a minimum value M such that the same inductance sensitivity K (nH) is obtained at different first length L1 (mm) and second length L2 (mm). The second length L2 (mm) is longer than the first length L1 (mm).

[0096] Also, even if the thickness dimension t (mm) of the bus bar 50 changes, the inductance sensitivity (nH) of the bus bar 50 does not change.

[0097] As shown in FIG. 7, the width dimension of the negative electrode side bus bar 51 and the width dimension of the positive electrode side bus bar 52 are substantially the same as each other. As shown in FIG. 8, the length dimension L- of the negative electrode side bus bar 51 and the length dimension L+ of the positive electrode side bus bar 52 are different from each other. The length dimension L- of the negative electrode side bus bar 51 corresponds to the first length L1. The length dimension L+ of the positive electrode side bus bar 52 corresponds to the second length L2. The length dimension L+ (second length L2) of the positive electrode side bus bar 52 is longer than the length dimension L- (first length L1) of the negative electrode side bus bar 51. However, due to the existence of the above-mentioned minimum value M, the inductance sensitivity of the negative electrode side bus bar 51 and the inductance sensitivity of the positive electrode side bus bar 52 are equal to each other.

[0098] (Position relationship between the power module and the coil) As shown in FIG. 7, the first U-phase power module 20u1 of the first power module group P1 is arranged at a position overlapping the first U-phase coil 17u1 of the first coil group C1 when viewed in the axial direction of the motor 3 (inverter 15). The first V-phase power module 20v1 of the first power module group P1 is arranged at a position overlapping the first V-phase coil 17v1 of the first coil group C1 when viewed in the axial direction of the motor 3. The first W-phase power module 20w1 of the first power module group P1 is arranged at a position overlapping the first W-phase coil 17w1 of the first coil group C1 when viewed in the axial direction of the motor 3.

[0099] As shown in Fig. 7, the second U-phase power module 20u2 of the second power module group P2 is arranged at a position overlapping the second U-phase coil 17u2 of the second coil group C2 when viewed in the axial direction of the motor 3 (inverter 15). The second V-phase power module 20v2 of the second power module group P2 is arranged at a position overlapping the second V-phase coil 17v2 of the second coil group C2 when viewed in the axial direction of the motor 3. The second W-phase power module 20w2 of the second power module group P2 is arranged at a position overlapping the second W-phase coil 17w2 of the second coil group C2 when viewed in the axial direction of the motor 3.

[0100] Specifically, at least a part of each power module 20 is arranged so as to overlap at least a part of each coil 17 when viewed in the axial direction of the motor 3 (inverter 15).

[0101] That is, as shown in Fig. 7, the distance du1 between the first U-phase power module 20u1 of the first power module group P1 and the first U-phase coil 17u1 of the first coil group C1, the distance dv1 between the first V-phase power module 20v1 of the first power module group P1 and the first V-phase coil 17v1 of the first coil group C1, and the distance dw1 between the first W-phase power module 20w1 of the first power module group P1 and the first W-phase coil 17w1 of the first coil group C1 are equal to each other when viewed in the axial direction of the motor 3 (inverter 15).

[0102] Similarly, as shown in Fig. 7, the distance du2 between the second U-phase power module 20u2 of the second power module group P2 and the second U-phase coil 17u2 of the second coil group C2, the distance dv2 between the second V-phase power module 20v2 of the second power module group P2 and the second V-phase coil 17v2 of the second coil group C2, and the distance dw2 between the second W-phase power module 20w2 of the second power module group P2 and the second W-phase coil 17w2 of the second coil group C2 are equal to each other when viewed in the axial direction of the motor 3 (inverter 15).

[0103] Further, as shown in FIG. 7, the distance du1 between the first U-phase power module 20u1 of the first power module group P1 and the first U-phase coil 17u1 of the first coil group C1, and the distance du2 between the second U-phase power module 20u2 of the second power module group P2 and the second U-phase coil 17u2 of the second coil group C2 are equal to each other when viewed in the axial direction of the motor 3 (inverter 15). The distance dv1 between the first V-phase power module 20v1 of the first power module group P1 and the first V-phase coil 17v1 of the first coil group C1, and the distance dv2 between the second V-phase power module 20v2 of the second power module group P2 and the second V-phase coil 17v2 of the second coil group C2 are equal to each other when viewed in the axial direction of the motor 3. The distance dw1 between the first W-phase power module 20w1 of the first power module group P1 and the first W-phase coil 17w1 of the first coil group C1, and the distance dw2 between the second W-phase power module 20w2 of the second power module group P2 and the second W-phase coil 17w2 of the second coil group C2 are equal to each other when viewed in the axial direction of the motor 3.

[0104] Each of the distances du1, dv1, dw1, du2, dv2, and dw2 is zero. The reference for each of the distances du1, dv1, dw1, du2, dv2, and dw2 may be set arbitrarily.

[0105] (Operational Effects of the First Embodiment) According to the present embodiment, since the first power module group P1 and the second power module group P2 are connected in parallel to each other in the inverter 15, the output of the motor 3 can be increased.

[0106] Further, since each power module 20 is arranged side by side on the same mounting surface 65 orthogonal to the axial direction of the motor 3, an increase in the axial length of the inverter 15 can be suppressed even though the number of power modules 20 is increased.

[0107] In addition, since the motor 3 and the inverter 15 are arranged adjacent to each other in the axial direction of the motor 3, the distance between each phase power module 20 and each phase coil 17 can be shortened. Therefore, the inductance of the electrical path (including the output bus bar 54) from each phase power module 20 to each phase coil 17 can be reduced.

[0108] Furthermore, at least in the first power module group P1 and the first coil group C1, the distances du1, dv1, dw1 between the phase power modules 20u1, 20v1, 20w1 and the phase coils 17u1, 17v1, 17w1 are equal to each other when viewed in the axial direction of the motor 3 among the U phase, V phase, and W phase. Therefore, at least in the first power module group P1 and the first coil group C1, the inductance of the electrical path (including the output bus bar 54) from each phase power module 20u1, 20v1, 20w1 to each phase coil 17u1, 17v1, 17w1 can be equalized among the U phase, V phase, and W phase.

[0109] As described above, while suppressing the increase in the size of the drive unit A composed of the motor 3 and the inverter 15, the output of the motor 3 can be increased, and the inductance of the electrical path from each phase power module 20 to each phase coil 17 can be reduced and equalized.

[0110] Also in the second power module group P2 and the second coil group C2, similar to the first power module group P1 and the first coil group C1, the distances du2, dv2, dw2 between the phase power modules 20u2, 20v2, 20w2 and the phase coils 17u2, 17v2, 17w2 are equal to each other when viewed in the axial direction of the motor 3 among the U phase, V phase, and W phase. Therefore, also in the second power module group P2 and the second coil group C2, similar to the first power module group P1 and the first coil group C1, the inductance of the electrical path (including the output bus bar 54) from each phase power module 20u2, 20v2, 20w2 to each phase coil 17u2, 17v2, 17w2 can be equalized among the U phase, V phase, and W phase.

[0111] Furthermore, between the first power module group P1 and the first coil group C1, and between the second power module group P2 and the second coil group C2, the inductance of the electrical path (including the output bus bar 54) from each phase power module 20u1, 20v1, 20w1, 20u2, 20v2, 20w2 to each phase coil 17u1, 17v1, 17w1, 17u2, 17v2, 17w2 can be equalized.

[0112] Each phase power module 20u1, 20v1, 20w1 of the first power module group P1 is arranged at a position overlapping each phase coil 17u1, 17v1, 17w1 of the first coil group C1 when viewed in the axial direction of the motor 3. Therefore, in the first power module group P1 and the first coil group C1, the distances du1, dv1, dw1 between each phase power module 20u1, 20v1, 20w1 and each phase coil 17u1, 17v1, 17w1 can be made shorter. For this reason, in the first power module group P1 and the first coil group C1, the inductance of the electrical path (including the output bus bar 54) from each phase power module 20u1, 20v1, 20w1 to each phase coil 17u1, 17v1, 17w1 can be further reduced.

[0113] Each phase power module 20u2, 20v2, 20w2 of the second power module group P2 is arranged at a position overlapping each phase coil 17u2, 17v2, 17w2 of the second coil group C2 when viewed in the axial direction of the motor 3. Therefore, also in the second power module group P2 and the second coil group C2, similar to the first power module group P1 and the first coil group C1, the distances du2, dv2, dw2 between each phase power module 20u2, 20v2, 20w2 and each phase coil 17u2, 17v2, 17w2 can be made shorter. For this reason, also in the second power module group P2 and the second coil group C2, similar to the first power module group P1 and the first coil group C1, the inductance of the electrical path (including the output bus bar 54) from each phase power module 20u2, 20v2, 20w2 to each phase coil 17u2, 17v2, 17w2 can be further reduced.

[0114] In the motor 3 (especially in the concentrated winding where the number of coils 17 is even), the coils 17 of the same phase are often arranged to face each other in the radial direction of the motor 3 (see FIG. 3). According to the present embodiment, the power modules 20 of the same phase are arranged to face each other in the radial direction of the motor 3, similarly to the coils 17 of the same phase. Thereby, it becomes easier to align each phase power module 20 with respect to each phase coil 17.

[0115] Since the smoothing capacitor 19 and each power module 20 are mounted on the same mounting surface 65 orthogonal to the axial direction of the motor 3, it is more advantageous in suppressing an increase in the axial length of the inverter 15. Furthermore, since the distance between the smoothing capacitor 19 and each power module 20 can be shortened, the inductance of the input bus bar 50 (negative electrode side bus bar 51 and positive electrode side bus bar 52) connecting the smoothing capacitor 19 and each power module 20 can be further reduced.

[0116] Since each power module 20 is arranged in the circumferential direction of the motor 3 on the outer peripheral side of the smoothing capacitor 19, the distances between the smoothing capacitor 19 and each power module 20 can be made equal to each other. Furthermore, by widening the input bus bar 50 (negative electrode side bus bar 51 and positive electrode side bus bar 52) along the circumferential direction of the motor 3, the inductance of the electrical path between the smoothing capacitor 19 and each power module 20 in the input bus bar 50 can be equalized.

[0117] In the input bus bar 50 (negative electrode side bus bar 51 and positive electrode side bus bar 52) connecting the smoothing capacitor 19 and each power module 20, by using the above-mentioned minimum value (inflection point) M (see FIG. 10), although the length dimension L- (first length L1) of the negative electrode side bus bar 51 and the length dimension L+ (second length L2) of the positive electrode side bus bar 52 are different from each other, the inductance of the negative electrode side bus bar 51 and the inductance of the positive electrode side bus bar 52 can be equalized with each other.

[0118] As shown by the two-dot chain line in FIG. 1, conventionally, the inverter 15' was often arranged in the vicinity of the second battery unit 12b' of the battery 12'. According to the present embodiment, since the inverter 15 can be arranged adjacent to the motor 3 in the axial direction, it is not necessary to arrange the inverter 15 in the vicinity of the second battery unit 12b. As a result, the degree of freedom in the layout of the second battery unit 12b is increased, and the second battery unit 12b can be enlarged.

[0119] Each phase power module 20u1, 20v1, 20w1 of the first power module group P1 is arranged at a position overlapping with each phase coil 17u1, 17v1, 17w1 of the first coil group C1 when viewed in the axial direction of the motor 3. Therefore, in the first power module group P1 and the first coil group C1, it is advantageous for equalizing the inductance of the electrical path from each phase power module 20u1, 20v1, 20w1 to each phase coil 17u1, 17v1, 17w1 among the U-phase, V-phase, and W-phase.

[0120] Each phase power module 20u2, 20v2, 20w2 of the second power module group P2 is arranged at a position overlapping with each phase coil 17u2, 17v2, 17w2 of the second coil group C2 when viewed in the axial direction of the motor 3. Therefore, also in the second power module group P2 and the second coil group C2, similar to the first power module group P1 and the first coil group C1, it is advantageous for equalizing the inductance of the electrical path from each phase power module 20u2, 20v2, 20w2 to each phase coil 17u2, 17v2, 17w2 among the U-phase, V-phase, and W-phase.

[0121] (First Modification Example of the First Embodiment) FIG. 11 is a diagram corresponding to FIG. 7 according to the first modification of the first embodiment. According to this modification, in both the first power module group P1 and the first coil group C1, and the second power module group P2 and the second coil group C2, each phase power module 20u1, 20v1, 20w1, 20u2, 20v2, 20w2 is not arranged at a position overlapping with each phase coil 17u1, 17v1, 17w1, 17u2, 17v2, 17w2 when viewed in the axial direction of the motor 3. Specifically, each phase power module 20u1, 20v1, 20w1, 20u2, 20v2, 20w2 is arranged with a shift in the circumferential direction of the motor 3 with respect to each phase coil 17u1, 17v1, 17w1, 17u2, 17v2, 17w2 when viewed in the axial direction of the motor 3.

[0122] The distances du1, dv1, dw1, du2, dv2, dw2 between each phase power module 20u1, 20v1, 20w1, 20u2, 20v2, 20w2 and each phase coil 17u1, 17v1, 17w1, 17u2, 17v2, 17w2 are equal to each other and are d (>0) when viewed in the axial direction of the motor 3.

[0123] (Second Modification of the First Embodiment) FIG. 12 is a diagram corresponding to FIG. 7 according to the second modification of the first embodiment. According to this modification, the stator of the motor 3 is further provided with a third U-phase coil 17u3 as the U-phase coil 17u, a third V-phase coil 17v3 as the V-phase coil 17v, and a third W-phase coil 17w3 as the W-phase coil 17w. The third U-phase coil 17u3, the third V-phase coil 17v3, and the third W-phase coil 17w3 constitute the third coil group C3.

[0124] The inverter 15 is further provided with a third U-phase power module 20u3 as the U-phase power module 20u, a third V-phase power module 20v3 as the V-phase power module 20v, and a third W-phase power module 20w3 as the W-phase power module 20w. The third U-phase power module 20u3, the third V-phase power module 20v3, and the third W-phase power module 20w3 constitute the third power module group P3.

[0125] Each of the phase power modules 20u1, 20v1, 20w1, 20u2, 20v2, 20w2, 20u3, 20v3, and 20w3 is arranged at a position overlapping with each of the phase coils 17u1, 17v1, 17w1, 17u2, 17v2, 17w2, 17u3, 17v3, and 17w3 when viewed in the axial direction of the motor 3. The distances du1, dv1, dw1, du2, dv2, dw2, du3, dv3, and dw3 between each of the phase power modules 20u1, 20v1, 20w1, 20u2, 20v2, 20w2, 20u3, 20v3, and 20w3 and each of the phase coils 17u1, 17v1, 17w1, 17u2, 17v2, 17w2, 17u3, 17v3, and 17w3 are equal to each other and zero when viewed in the axial direction of the motor 3.

[0126] According to this modification, by connecting the first power module group P1, the second power module group P2, and the third power module group P3 in three parallel, the output of the motor 3 can be further increased.

[0127] (Third Modification of the First Embodiment) FIG. 13A is a view corresponding to FIG. 7 according to the third modification of the first embodiment. The inverter 16 according to this modification is arranged adjacent to the in-wheel motor 14 in the axial direction (vehicle width direction) of the in-wheel motor 14 (see FIG. 1). The inverter 16 is not provided with an axial through hole 40 and a boss portion 41. The smoothing capacitor 19 is formed in a columnar shape. The smoothing capacitor 19 is not provided with an axial through hole.

[0128] (Fourth Modification of the First Embodiment) FIG. 13B shows the output bus bar 54 according to the fourth modification of the first embodiment. The output bus bar 54 according to this modification is configured to be wide along the circumferential direction of the motor 3. In other words, the width direction of the output bus bar 54 extends in the circumferential direction (arc shape). The output bus bar 54 is fan-shaped. This makes it easier to widen the output bus bar 54, and thus it is easier to reduce the inductance of the output bus bar 54.

[0129] (Other Modifications of the First Embodiment) The number of coil groups in the motor 3 and the number of power module groups in the inverter 15 may be different from each other. For example, the number of coil groups in the motor 3 may be three (nine coils), while the number of power module groups in the inverter 15 may be two (six power modules). Conversely, the number of coil groups in the motor 3 may be two (six coils), while the number of power module groups in the inverter 15 may be three (nine power modules 20).

[0130] Although not shown, in the motor 3, each of the U-phase coil 17u, the V-phase coil 17v, and the W-phase coil 17w may be wound in a distributed manner.

[0131] In the input bus bar 50, the length dimension L- of the negative electrode side bus bar 51 may be the second length L2, while the length dimension L+ of the positive electrode side bus bar 52 may be the first length L1.

[0132] The mounting surface 65 may be composed of a plurality of surfaces located on the same plane orthogonal to the axial direction of the motor 3.

[0133] <Second Embodiment>[ FIG. 14 is a cross-sectional view corresponding to FIG. 7 according to the second embodiment, showing the inverter 15 as seen from the side opposite to the motor 3. FIG. 15 is a longitudinal sectional view corresponding to FIG. 8 according to the second embodiment, showing the inverter 15. Hereinafter, detailed descriptions of the same configurations as those in the above embodiments may be omitted.

[0134] In the present embodiment, each power module 20 is disposed on the outer peripheral side of the smoothing capacitor 19. Each power module 20 is arranged side by side in the circumferential direction of the motor 3 on the outer peripheral side of the smoothing capacitor 19.

[0135] Then, the input terminals 35 and 36 (the first end face 33) and the output terminal 37 (the second end face 34) of each power module 20 face the radial direction of the motor 3 (inverter 15). Specifically, the input terminals 35 and 36 (the first end face 33) of each power module 20 face the inner peripheral side. The output terminal 37 (the second end face 34) of each power module 20 faces the outer peripheral side. Each power module 20 is arranged radially with the center O of the inverter 15 (motor 3) as the starting point.

[0136] As shown in FIG. 14, the width dimension of the negative-side bus bar 51 and the width dimension of the positive-side bus bar 52 are the same as each other. As shown in FIG. 15, the length dimension L− of the negative-side bus bar 51 and the length dimension L+ of the positive-side bus bar 52 are the same as each other. Therefore, the inductance of the negative-side bus bar 51 and the inductance of the positive-side bus bar 52 are equal to each other.

[0137] Other configurations are the same as those in the first embodiment.

[0138] <The Third Embodiment> FIG. 16 is a cross-sectional view corresponding to FIG. 7 according to the third embodiment, which is a cross-sectional view of the inverter 15 viewed from the side opposite to the motor 3. FIG. 17 is a longitudinal sectional view corresponding to FIG. 8 according to the third embodiment, which is a longitudinal sectional view of the inverter 15. Hereinafter, detailed descriptions of the same configurations as those in the above embodiments may be omitted.

[0139] As shown in FIGS. 16 and 17, the negative-side input terminal 35 is connected to the lower side of the first end face 33 of each power module 20. The positive-side input terminal 36 is connected to the lower side of the second end face 34 of each power module 20. The output terminal 37 is connected to the center of the upper surface 32 of each power module 20.

[0140] The negative-side bus bar 51 connects the negative terminal 19c of the smoothing capacitor 19 and the negative-side input terminal 35 of each power module to each other. The positive-side bus bar 52 connects the positive terminal 19d of the smoothing capacitor 19 and the positive-side input terminal 36 of each power module 20 to each other.

[0141] The positive electrode side bus bar 52 starts from the positive electrode terminal 19d (one end portion 52i) of the smoothing capacitor 19 and extends along the upper surface 32 from the first end surface 33 side to the second end surface 34 side of each power module 20. Thereafter, the positive electrode side bus bar 52 bends downward and extends to the lower positive electrode side input terminal 36 (the other end portion 52o) along the second end surface 34. In other words, the positive electrode side bus bar 52 extends so as to wind each power module 20 from the upper surface 32 side. Each output bus bar 54 starts from the output terminal 37 on the upper surface 32 of each power module 20 and extends upward. Three openings are provided in the positive electrode side bus bar 52 for allowing three output bus bars 54 extending upward to pass through.

[0142] As shown in FIG. 16, the width dimension of the negative electrode side bus bar 51 and the width dimension of the positive electrode side bus bar 52 are the same as each other. As shown in FIG. 17, the length dimension (L-) of the negative electrode side bus bar 51 and the length dimension (the sum of La+ and Lb+) of the positive electrode side bus bar 52 are different from each other. The length dimension (L-) of the negative electrode side bus bar 51 corresponds to the first length L1. The length dimension (the sum of La+ and Lb+, the second length L2) of the positive electrode side bus bar 52 corresponds to the second length L2. The length dimension (the sum of La+ and Lb+, the second length L2) of the positive electrode side bus bar 52 is longer than the length dimension (L-, the first length L1) of the negative electrode side bus bar 51. However, due to the existence of the above-mentioned minimum value M (see FIG. 10), the inductance of the negative electrode side bus bar 51 and the inductance of the positive electrode side bus bar 52 are equal to each other.

[0143] Note that the conditions (such as the material) of the negative electrode side bus bar 51 and the positive electrode side bus bar 52 according to this embodiment are different from those in the above embodiment. Therefore, the aspect of the above-mentioned minimum value M (see FIG. 10) is also different. Specifically, the interval (difference) between the first length L1 and the second length L2 is larger than that in the above embodiment.

[0144] Other configurations are the same as those in the second embodiment.

[0145] (First modification of the third embodiment) FIG. 18 is a diagram corresponding to FIG. 8 according to the first modification of the third embodiment, and is a longitudinal sectional view of the inverter 15. In the above embodiment, each power module 20 accommodates both the lower arm element 21 and the upper arm element 22 in one package, but this is different in this modification. In this modification, each power module 20 is separated into a first package 20a that accommodates the lower arm element 21 and a second package 20b that accommodates the upper arm element 22.

[0146] (Second Modification of the Third Embodiment) FIG. 19 is a perspective view of the power module 20 and the bus bar 50 according to the second modification of the third embodiment. In this modification, each power module 20 is arranged linearly side by side. The width direction of each of the bus bars 51 and 52 extends linearly (the direction in which the power modules 20 are arranged). Even in this case, at least in the first power module group P1 and the first coil group C1, the distances du1, dv1, and dw1 between the phase power modules 20u1, 20v1, and 20w1 and the phase coils 17u1, 17v1, and 17w1 only need to be equal to each other in the axial direction of the motor 3 when viewed among the U phase, V phase, and W phase.

[0147] <Other Embodiments> As described above, the present disclosure has been described with reference to the preferred embodiments, but such descriptions are not limiting matters, and of course, various modifications are possible.

Industrial Applicability

[0148] Since the present disclosure can be applied to a drive unit of a vehicle, it is extremely useful and has high industrial applicability.

Explanation of Signs

[0149] A Drive unit L1 First length L2 Second length K Inductance sensitivity M Minimum value du1, dv1, dw1, du2, dv2, dw2 Distances 1 Vehicle 3 Drive motor 14 In-wheel motor 15 Inverter 16 Inverter 17 Coil 17u U-phase coil 17v V-phase coil 17w W-phase coil 19 Smoothing capacitor 20 Power module 20u U-phase power module 20v V-phase power module 20w W-phase power module 50 Input busbar 51 Negative-side busbar 51i One end 51o The other end 52 Positive-side busbar 52i One end 52o The other end 54 Output busbar 60 Heat sink 65 Mounting surface

Claims

1. A drive unit for a vehicle in which a motor and an inverter having a plurality of power modules are arranged adjacent to each other in the axial direction of the motor, each of the power modules is placed on a mounting surface orthogonal to the axial direction, in the motor, at least a first coil group and a second coil group are configured as a coil group including one U-phase coil, one V-phase coil, and one W-phase coil each, the plurality of power modules constitute at least a first power module group and a second power module group connected in parallel with each other, each of the first power module group and the second power module group includes one U-phase power module, one V-phase power module, and one W-phase power module corresponding to the U-phase coil, the V-phase coil, and the W-phase coil, respectively, each of the power modules in the first power module group is connected to each of the coils in the first coil group, each of the power modules in the second power module group is connected to each of the coils in the second coil group, the distance between the U-phase power module in the first power module group and the U-phase coil in the first coil group, the distance between the V-phase power module in the first power module group and the V-phase coil in the first coil group, and the distance between the W-phase power module in the first power module group and the W-phase coil in the first coil group are equal to each other when viewed in the axial direction, the inverter has a smoothing capacitor placed on the mounting surface, the smoothing capacitor and each of the power modules are connected to each other by a negative-side bus bar and a positive-side bus bar as input bus bars, one end of the input bus bar is connected to the smoothing capacitor, the other end of the input bus bar is connected to each of the power modules, the inductance of the input bus bar is a function of the length from the one end to the other end in the input bus bar, the function has a minimum value such that the same inductance is obtained at different first and second lengths, the length of one of the negative-side bus bar and the positive-side bus bar is the first length, the length of the other of the negative-side bus bar and the positive-side bus bar is the second length, a drive unit for a vehicle.

2. In the drive unit for a vehicle according to Claim 1, The distance between the U-phase power module of the second power module group and the U-phase coil of the second coil group, the distance between the V-phase power module of the second power module group and the V-phase coil of the second coil group, and the distance between the W-phase power module of the second power module group and the W-phase coil of the second coil group are equal to each other when viewed in the axial direction, a drive unit of a vehicle.

3. In the drive unit of a vehicle according to claim 1 or 2, the distance between the U-phase power module of the first power module group and the U-phase coil of the first coil group and the distance between the U-phase power module of the second power module group and the U-phase coil of the second coil group are equal to each other when viewed in the axial direction, the distance between the V-phase power module of the first power module group and the V-phase coil of the first coil group and the distance between the V-phase power module of the second power module group and the V-phase coil of the second coil group are equal to each other when viewed in the axial direction, the distance between the W-phase power module of the first power module group and the W-phase coil of the first coil group and the distance between the W-phase power module of the second power module group and the W-phase coil of the second coil group are equal to each other when viewed in the axial direction, a drive unit of a vehicle.

4. In the drive unit of a vehicle according to any one of claims 1 to 3, in the motor, each of the U-phase coil, the V-phase coil, and the W-phase coil is concentrated wound so as to be arranged at at least two locations, the U-phase power module of the first power module group is arranged at a position overlapping the U-phase coil of the first coil group when viewed in the axial direction, the V-phase power module of the first power module group is arranged at a position overlapping the V-phase coil of the first coil group when viewed in the axial direction, the W-phase power module of the first power module group is arranged at a position overlapping the W-phase coil of the first coil group when viewed in the axial direction, a drive unit of a vehicle.

5. In the drive unit of a vehicle according to claim 4, the U-phase power module of the second power module group is arranged at a position overlapping the U-phase coil of the second coil group when viewed in the axial direction, The V-phase power module of the second power module group is arranged at a position overlapping the V-phase coil of the second coil group when viewed in the axial direction. The W-phase power module of the second power module group is arranged at a position overlapping the W-phase coil of the second coil group when viewed in the axial direction, in a drive unit of a vehicle.

6. In the drive unit of a vehicle according to any one of Claims 1 to 5, Each power module of the first power module group is arranged on one side in the radial direction of the motor. Each power module of the second power module group is arranged on the other side in the radial direction. The U-phase power module of the first power module group and the U-phase power module of the second power module group face each other in the radial direction. The V-phase power module of the first power module group and the V-phase power module of the second power module group face each other in the radial direction. The W-phase power module of the first power module group and the W-phase power module of the second power module group face each other in the radial direction, in a drive unit of a vehicle.

7. In the drive unit of a vehicle according to any one of Claims 1 to 6, At least an output bus bar is interposed between each power module and each coil. The output bus bar is configured to be wide so as to extend along the circumferential direction of the motor, in a drive unit of a vehicle.

8. A drive unit of a vehicle in which a motor and an inverter having a plurality of power modules are arranged adjacent to each other in the axial direction of the motor, Each of the power modules is placed on a mounting surface orthogonal to the axial direction. In the motor, at least a first coil group and a second coil group are configured as a coil group including one U-phase coil, one V-phase coil, and one W-phase coil respectively. The plurality of power modules constitute at least a first power module group and a second power module group connected in parallel with each other. The first power module group and the second power module group each include one U-phase power module, one V-phase power module, and one W-phase power module corresponding to the U-phase coil, the V-phase coil, and the W-phase coil respectively. Each of the power modules in the first power module group is connected to each of the coils in the first coil group. Each of the power modules in the second power module group is connected to each of the coils in the second coil group. The U-phase power module in the first power module group is arranged at a position overlapping the U-phase coil in the first coil group when viewed in the axial direction. The V-phase power module in the first power module group is arranged at a position overlapping the V-phase coil in the first coil group when viewed in the axial direction. The W-phase power module in the first power module group is arranged at a position overlapping the W-phase coil in the first coil group when viewed in the axial direction. The inverter has a smoothing capacitor placed on the mounting surface. The smoothing capacitor and each of the power modules are connected to each other by a negative-side bus bar and a positive-side bus bar as input bus bars. One end of the input bus bar is connected to the smoothing capacitor. The other end of the input bus bar is connected to each of the power modules. The inductance of the input bus bar is a function of the length from one end to the other end of the input bus bar. The function has a minimum value such that the same inductance is obtained at different first and second lengths. The length of one of the negative-side bus bar and the positive-side bus bar is the first length. The length of the other of the negative-side bus bar and the positive-side bus bar is the second length, a drive unit of a vehicle.

9. In the drive unit of a vehicle according to claim 8, The U-phase power module in the second power module group is arranged at a position overlapping the U-phase coil in the second coil group when viewed in the axial direction. The V-phase power module in the second power module group is arranged at a position overlapping the V-phase coil in the second coil group when viewed in the axial direction. The W-phase power module in the second power module group is arranged at a position overlapping the W-phase coil in the second coil group when viewed in the axial direction, a drive unit of a vehicle.

10. A drive unit of a vehicle in which a motor and an inverter having a plurality of power modules are arranged adjacent to each other in the axial direction of the motor. Each of the power modules is placed on a mounting surface orthogonal to the axial direction. In the motor, at least a first coil group and a second coil group are configured as a coil group including one U-phase coil, one V-phase coil, and one W-phase coil each. The plurality of power modules constitute at least a first power module group and a second power module group connected in parallel to each other. Each of the first power module group and the second power module group includes one U-phase power module, one V-phase power module, and one W-phase power module corresponding to the U-phase coil, the V-phase coil, and the W-phase coil, respectively. Each of the power modules in the first power module group is connected to each of the coils in the first coil group. Each of the power modules in the second power module group is connected to each of the coils in the second coil group. The distance between the U-phase power module in the first power module group and the U-phase coil in the first coil group, the distance between the V-phase power module in the first power module group and the V-phase coil in the first coil group, and the distance between the W-phase power module in the first power module group and the W-phase coil in the first coil group are equal to each other when viewed in the axial direction. The mounting surface is constituted by a wall portion of a heat sink provided on the motor side in the inverter. The inverter has a smoothing capacitor placed on the mounting surface. The smoothing capacitor is arranged at the center of the inverter. Each of the power modules is arranged side by side in the circumferential direction of the motor on the outer peripheral side of the smoothing capacitor. A drive unit of a vehicle.

11. In the drive unit of a vehicle according to claim 10, The distance between the U-phase power module in the second power module group and the U-phase coil in the second coil group, the distance between the V-phase power module in the second power module group and the V-phase coil in the second coil group, and the distance between the W-phase power module in the second power module group and the W-phase coil in the second coil group are equal to each other when viewed in the axial direction. A drive unit of a vehicle.

12. In the drive unit of a vehicle according to claim 10 or 11, The distance between the U-phase power module of the first power module group and the U-phase coil of the first coil group, and the distance between the U-phase power module of the second power module group and the U-phase coil of the second coil group are equal to each other when viewed in the axial direction. The distance between the V-phase power module of the first power module group and the V-phase coil of the first coil group, and the distance between the V-phase power module of the second power module group and the V-phase coil of the second coil group are equal to each other when viewed in the axial direction. The distance between the W-phase power module of the first power module group and the W-phase coil of the first coil group, and the distance between the W-phase power module of the second power module group and the W-phase coil of the second coil group are equal to each other when viewed in the axial direction, which is a drive unit of a vehicle.

13. A drive unit of a vehicle in which a motor and an inverter having a plurality of power modules are arranged adjacent to each other in the axial direction of the motor. Each of the power modules is placed on a mounting surface orthogonal to the axial direction. In the motor, at least a first coil group and a second coil group are configured as a coil group including one U-phase coil, one V-phase coil, and one W-phase coil respectively. The plurality of power modules constitute at least a first power module group and a second power module group connected in parallel with each other. The first power module group and the second power module group each include one U-phase power module, one V-phase power module, and one W-phase power module corresponding to the U-phase coil, the V-phase coil, and the W-phase coil respectively. Each of the power modules in the first power module group is connected to each of the coils in the first coil group. Each of the power modules in the second power module group is connected to each of the coils in the second coil group. The U-phase power module of the first power module group is arranged at a position overlapping the U-phase coil of the first coil group when viewed in the axial direction. The V-phase power module of the first power module group is arranged at a position overlapping the V-phase coil of the first coil group when viewed in the axial direction. The W-phase power module of the first power module group is arranged at a position overlapping the W-phase coil of the first coil group when viewed in the axial direction. The placement surface is constituted by a wall portion of a heat sink provided on the motor side in the inverter. The inverter has a smoothing capacitor placed on the placement surface. The smoothing capacitor is arranged at the center of the inverter. Each of the power modules is arranged side by side in the circumferential direction of the motor on the outer peripheral side of the smoothing capacitor, which is a drive unit of a vehicle.

14. In the drive unit of a vehicle according to Claim 13, The U-phase power module of the second power module group is arranged at a position overlapping the U-phase coil of the second coil group when viewed in the axial direction. The V-phase power module of the second power module group is arranged at a position overlapping the V-phase coil of the second coil group when viewed in the axial direction. The W-phase power module of the second power module group is arranged at a position overlapping the W-phase coil of the second coil group when viewed in the axial direction, which is a drive unit of a vehicle.

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