Drive device

Abstract

The invention provides a technique capable of suppressing a temperature difference between two drive motors during charging of a battery. A drive device for an electric vehicle having a battery may also include a first motor and a second motor electrically connected to the battery and driving at least one drive wheel of the electric vehicle. The drive device may also include a control device that controls the current flowing to the first motor and the current flowing to the second motor, respectively. The control device may be configured so as to be able to execute: a charging process in which power from an external power source is supplied to the battery via a neutral point of the first motor; and an energizing process in which a d-axis current is energized to the second motor during the charging process.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a drive device for an electric vehicle. Background Art

[0002] Patent document 1 discloses an electric vehicle having two drive motors driving at least one drive wheel of the electric vehicle. As also mentioned in patent document 1, such an electric vehicle has the following problem: if the temperature difference between the two drive motors increases, the torques outputted from the two drive motors become unbalanced, thereby reducing the driving stability.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-63587

[0004] In addition, an electric vehicle is being developed that is configured to charge a battery via a drive motor of either of two drive motors. In such an electric vehicle, during the charging of the battery, the temperature difference between the drive motor used for charging and the drive motor not used for charging becomes large. Therefore, there is a concern that if the electric vehicle is moved after charging is completed, the driving stability will be reduced. This specification provides a technology that can suppress the temperature difference between the two drive motors during the charging of the battery. Summary of the invention

[0005] The technology disclosed in this specification can be applied to a drive device for an electric vehicle having a battery. The drive device may also include a first motor and a second motor that are electrically connected to the battery and drive at least one drive wheel of the electric vehicle. The drive device may also include a control device that controls the current flowing to the first motor and the current flowing to the second motor respectively. The control device may also be configured to be able to perform: a charging process in which electric power from an external power source is supplied to the battery via the neutral point of the first motor; and a power-on process in which a d-axis current is supplied to the above-mentioned second motor.

[0006] According to the driving device, by supplying the d-axis current to the second motor not used for charging, the temperature of the second motor not used for charging rises, and the temperature difference between the first and second motors decreases. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a block diagram of an electric car.

[0008] Figure 2 This is a flowchart of the warm-up process for the drive motor.

[0009] Figure 3A This is a diagram for explaining a situation when the electric vehicle is moving forward when the temperature difference between the magnets of the left and right drive motors is large.

[0010] Figure 3BThis is a diagram for explaining a situation when the electric vehicle is moving forward when the temperature difference between the magnets of the left and right drive motors is small.

[0011] Figure 4 It is a block diagram of the electric vehicle 1 as viewed from above.

[0012] Figure 5 yes Figure 4 Cross-sectional view at line VV of FIG.

[0013] Figure 6 This is a block diagram of the electric vehicle 301 as viewed from above.

[0014] Description of Reference Numerals

[0015] 1…electric vehicle; 2…battery pack; 3…left drive unit; 4…right drive unit; 5…motor control device; 6…charging socket; 7…external DC power supply; INV1…first inverter; INV2…second inverter; M1…first drive motor; M2…second drive motor. DETAILED DESCRIPTION

[0016] In one embodiment of the present technology, the control device may be configured to execute the energization process when a temperature difference between the first motor and the second motor is equal to or greater than a predetermined value during the charging process.

[0017] According to such a configuration, for example, when the temperature difference between the first motor and the second motor is small, the energization process may not be performed. Therefore, the temperature increase process can be performed with good energy efficiency.

[0018] In one embodiment of the present technology, the temperature difference may be a difference between a magnet temperature of a rotor of the first motor and a magnet temperature of a rotor of the second motor.

[0019] The torque output by the first and second motors depends on the magnet temperature of the rotor. According to the above configuration, the temperature difference between the magnet temperature of the rotor of the first motor and the magnet temperature of the rotor of the second motor can be reduced, thereby reducing the difference in output torque.

[0020] In one embodiment of the present technology, the control device may control the magnitude of the d-axis current supplied to the second motor according to a temperature difference between the first motor and the second motor.

[0021] According to such a configuration, for example, when the temperature difference is small, the current can be reduced, and the temperature increase process can be performed with good energy efficiency.

[0022] In one embodiment of the present technology, the control device may be configured to further perform: a first estimation process of estimating a required charging time required to complete the charging of the battery through the charging process; and a second estimation process of estimating a required heating time required to make the temperature difference between the first motor and the second motor fall below a predetermined value through the energization process. The control device may also be configured to start the energization process in response to the reduction of the required charging time to less than the required heating time.

[0023] According to such a configuration, the time required for charging can be made consistent with the time required for temperature rise, and therefore, the temperature difference can be made within a predetermined value at the time of completion of charging.

[0024] In one embodiment of the present technology, the control device may be configured to execute a process of monitoring the temperature difference during the charging process, and may be configured to execute the first estimation process and the second estimation process when the temperature difference exceeds the predetermined value.

[0025] According to such a configuration, for example, when the temperature difference between the first motor and the second motor is small, the first estimation process and the second estimation process may not be executed. The burden on the control device can be reduced.

[0026] In one embodiment of the present technology, the driving wheels may be a left wheel and a right wheel. The first motor may drive one of the left wheel and the right wheel, and the second motor may drive the other of the left wheel and the right wheel.

[0027] In one embodiment of the present technology, the driving wheels may be the front wheels and rear wheels of the electric vehicle. The first motor may drive one of the front wheels and the rear wheels, and the second motor may drive the other of the front wheels and the rear wheels.

[0028] In one embodiment of the present technology, an inverter circuit may be further provided, the inverter circuit having a plurality of switching elements and electrically connected between the battery and the first motor. The control device may also be configured such that the inverter circuit functions as a boost circuit together with the plurality of windings of the first motor by controlling the plurality of switching elements during the charging process.

[0029] According to such a configuration, the battery can be charged via the first motor.

[0030] [Example 1]

[0031] like Figure 1As shown, the electric vehicle 1 includes a battery pack 2, a left drive unit 3, a right drive unit 4, a motor control device 5, and a charging socket 6. In addition, the "electric vehicle" in this specification includes a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a fuel cell electric vehicle (FCEV), etc.

[0032] The left drive unit 3 is provided corresponding to the left drive wheel of the electric vehicle 1, and has a first inverter INV1 and a first drive motor M1. The first inverter INV1 is a three-phase inverter circuit. In the first inverter INV1, the DC positive terminal is connected to the positive pole of the battery pack 2, the DC negative terminal is connected to the negative pole of the battery pack 2, and the midpoint of each phase arm is connected to the first drive motor M1. The first inverter INV1 is appropriately controlled according to the first control signal PWM1 output from the motor control device 5. The first drive motor M1 is a three-phase AC motor with three windings. One end of each of the three windings is connected to the midpoint of the corresponding phase arm of the first inverter INV1, and the other end of each of the three windings is connected at the neutral point through a star connection.

[0033] The left drive unit 3 has a current sensor provided in each of the two-phase cables (for example, the V phase and the W phase) in the cable from the first inverter INV1 to the first drive motor M1. These current sensors measure the current Iv1 flowing in the V-phase cable and the current Iw1 flowing in the W-phase cable, and output the measured currents Iv1 and Iw1 to the motor control device 5. The left drive unit 3 also has a temperature sensor and a rotation angle sensor provided in the first drive motor M1. The temperature sensor outputs the measured motor temperature T1 to the motor control device 5. The rotation angle sensor measures the rotation angle Q1 (that is, the rotation position of the rotor relative to the stator) of the first drive motor M1, and outputs the measured rotation angle Q1 to the motor control device 5.

[0034] The right drive unit 4 is provided corresponding to the right drive wheel of the electric vehicle 1 and includes a second inverter INV2 and a second drive motor M2. The structure of the right drive unit 4 is substantially the same as that of the left drive unit 3, and thus the description thereof is omitted.

[0035] The motor control device 5 is configured to generate a first control signal PWM1 for controlling the first inverter INV1 and a second control signal PWM2 for controlling the second inverter INV2. The motor control device 5 generates the control signals PWM1 and PWM2 based on the torque command value in a mode of driving the drive motors M1 and M2. As described later, the motor control device 5 generates the control signals PWM1 and PWM2 based on the d-axis current command value in a mode of charging the battery pack 2. In addition, the d-axis and q-axis currents measured based on the currents Iv1 and Iw1 and the rotation angle Q1 are used for feedback control when generating the control signals PWM1 and PWM2.

[0036] The charging socket 6 is provided on the body of the electric vehicle 1. The charging socket 6 is configured to be connected to an external DC power source 7 (for example, a charging station) via a power cable. The charging socket 6 is provided corresponding to either the left drive unit 3 or the right drive unit 4. In this example, the charging socket 6 is provided corresponding to the left drive unit 3. One of a pair of terminals of the charging socket 6 is connected to the neutral point of the first drive motor M1, and the other of the pair of terminals of the charging socket 6 is connected to the negative electrode of the battery pack 2 via the first inverter INV1.

[0037] In the wiring from the charging socket 6 to the battery pack 2, a boost circuit is formed by the lower switch element and the upper diode of one of the three phase arms constituting the first inverter INV1, and the winding of the first drive motor M1 connected to the midpoint of the phase arm. Similarly, the three phase arms constitute a boost circuit respectively. In this way, the first inverter INV1 and the first drive motor M1 can be regarded as three boost circuits connected in parallel between the charging socket 6 and the battery pack 2. The electric vehicle 1 uses the first inverter INV1 and the first drive motor M1 as a boost circuit, so that the battery pack 2 can be quickly charged even when the output voltage of the external DC power supply 7 is lower than that of the battery pack 2.

[0038] Below, refer to Figure 2 , the warm-up process performed by the motor control device 5 is described. When the power cable of the external DC power supply 7 is connected to the charging socket 6 and the user turns on the charging switch (not shown), the warm-up process is performed. Figure 2 The motor control device 5 estimates the magnet temperature of the rotor of the first drive motor M1 based on the motor temperature T1 measured by the first temperature sensor 39L provided in the first drive motor M1, and estimates the magnet temperature of the rotor of the second drive motor M2 based on the motor temperature T2 measured by the second temperature sensor 39R provided in the second drive motor M2 (step S1). The estimation of the magnet temperature is not particularly limited, but for example, it can be estimated using a prescribed function, or it can be estimated using a table recording the correspondence between the motor temperature and the magnet temperature.

[0039] Next, the motor control device 5 determines whether the difference between the estimated value of the magnet temperature of the first drive motor M1 and the estimated value of the magnet temperature of the second drive motor M2 is greater than the deflection allowable magnet temperature difference (step S2). When the estimated value difference of the magnet temperature is less than the deflection allowable magnet temperature difference, the process ends. And the process returns to step S1 to perform a loop process. The loop process can also be performed in a predetermined period. In addition, the loop process can also be performed while the charging switch (not shown) is in the on state. When the estimated value difference of the magnet temperature is greater than the deflection allowable difference, the process proceeds to step S3.

[0040] Here, the torque output by the drive motors M1 and M2 depends on the magnet temperature of the drive motors M1 and M2. The lower the magnet temperature, the greater the torque output by the drive motors M1 and M2. The first drive motor M1 is used for neutral point charging, so the magnet temperature of the first drive motor M1 rises. Therefore, if the charging time becomes longer, the difference between the magnet temperature of the first drive motor M1 and the magnet temperature of the second drive motor M2 becomes larger. Figure 3A The figure shows the situation when the electric vehicle 1 is moving forward when the magnet temperature difference is greater than the deflection allowable magnet temperature difference. Figure 3B The figure shows the electric vehicle 1 moving forward when the magnet temperature difference is within the deflection allowable magnet temperature difference. If the magnet temperature difference is greater than the deflection allowable magnet temperature difference, the difference between the torque output by the first drive motor M1 and the torque output by the second drive motor M2 becomes larger, causing deflection during forward movement (see Figure 3A ) In addition, the deflection-permitting magnet temperature difference is set to a magnet temperature difference that produces a maximum permissible deflection when the electric vehicle 1 moves forward.

[0041] The motor control device 5 estimates the charging completion time based on the SOC estimated value and the charging current value of the battery pack 2 (step S3). The charging completion time is the time required for the battery to be fully charged. Next, the motor control device 5 estimates the time required for the difference between the estimated value of the magnet temperature of the first drive motor M1 and the estimated value of the magnet temperature of the second drive motor M2 to reach below the deflection-allowed magnet temperature difference when a specified d-axis current is supplied to the second drive motor M2 to heat up the magnet of the second drive motor M2, that is, the heating completion time of the second drive motor M2 (step S4). In addition, the heating completion time can also be calculated as the time after adding a specified time to the time required for the estimated value difference of the magnet temperature to be consistent with the deflection-allowed magnet temperature difference.

[0042] The motor control device 5 determines whether the charging completion time estimated in step S3 is less than the heating completion time estimated in step S4 (step S5). If the charging completion time is longer than the heating completion time, the process ends. Then, the process returns to step S1 and the loop process is performed. If the charging completion time is less than the heating completion time, the process proceeds to step S6.

[0043] The motor control device 5 generates the second control signal PWM2 based on the d-axis current command value, and supplies a specified d-axis current to the second drive motor M2. Since only the d-axis current is supplied to the second drive motor M2, the second drive motor M2 does not output torque. Moreover, since the charging completion time and the heating completion time are made consistent through step S5, the charging and heating are completed almost at the same time. Therefore, if the charging is completed, the difference between the estimated value of the magnet temperature of the first drive motor M1 and the estimated value of the magnet temperature of the second drive motor M2 is less than the deflection allowable magnet temperature difference. Therefore, when the user attempts to start driving the electric vehicle 1 and move the electric vehicle 1 forward immediately after charging, the difference between the torque output by the first drive motor M1 and the torque output by the second drive motor M2 is small enough, so that stable driving can be achieved (refer to Figure 3B ).

[0044] (Effect)

[0045] exist Figure 2 In the warm-up process of the drive motor shown in the figure, the temperature of the second drive motor M2 is increased in accordance with the completion of charging. Therefore, the power consumption can be suppressed, and the estimated value difference of the magnet temperature can be within the deflection allowable magnet temperature difference at the time of charging completion. In addition, as needed, the temperature of the second drive motor M2 can be increased at any time when the estimated value difference of the magnet temperature during charging reaches or exceeds the deflection allowable magnet temperature difference.

[0046] exist Figure 2 In the warm-up process shown, during the period when the charging switch is in the on state (i.e., during the charging process), when the temperature difference between the estimated value of the magnet temperature of the first drive motor M1 and the estimated value of the magnet temperature of the second drive motor M2 is greater than the deflection allowable magnet temperature difference (S2: Y), the power-on process of step S6 can be performed. Thus, for example, when the temperature difference between the first drive motor M1 and the second drive motor M2 is small, the power-on process of step S6 can be omitted. Therefore, the warm-up process can be performed with good energy efficiency.

[0047] pass Figure 2 In step S2, while the charging switch is in the on state (i.e., during the charging process), the temperature difference between the estimated value of the magnet temperature of the first drive motor M1 and the estimated value of the magnet temperature of the second drive motor M2 can be monitored. Moreover, based on whether the temperature difference reaches a deflection-allowed magnet temperature difference or above, the process of estimating the charging completion time (S3) and the process of estimating the heating completion time (S4) can be executed. Thus, for example, when the temperature difference between the first drive motor M1 and the second drive motor M2 is small, the processes of steps S3 and S4 can be omitted. The burden on the motor control device 5 can be reduced.

[0048] [Example 2]

[0049] Embodiment 2 is a specific structural example of the contents described in Embodiment 1. Figure 4 2 is a block diagram of an electric vehicle 1 equipped with a drive device 20 as viewed from above. Figure 4 In the figure, the front of the electric vehicle 1 is indicated as "FR", the left is indicated as "LH", and the upper side is indicated as "UP". The same is true in the following drawings.

[0050] The electric vehicle 1 includes a vehicle body 12, a battery pack 2, a pair of left and right front wheels 4L, 4R, a pair of left and right rear wheels 5L, 5R, and a charging socket 6 in addition to a drive device 20. The drive device 20 includes a first drive motor M1, a second drive motor M2, a first inverter INV1, a second inverter INV2, a first power transmission mechanism 50L, and a second power transmission mechanism 50R.

[0051] The driving device 20 drives the pair of front wheels 4L and 4R by supplying the power of the battery pack 2 to the first driving motor M1 and the second driving motor M2. Thus, the electric vehicle 1 is driven. That is, the pair of front wheels 4L and 4R are the driving wheels of the electric vehicle 1. In a modified example, the pair of rear wheels 5L and 5R may also be the driving wheels of the electric vehicle 1.

[0052] The first drive motor M1 and the second drive motor M2 are symmetrically arranged with respect to the center line CL1 in the left-right direction of the electric vehicle 1, and have the same structure. The first drive motor M1 is located on the left of the center line CL1, and the second drive motor M2 is located on the right of the center line CL1. The first inverter INV1 is arranged above the first drive motor M1, and the second inverter INV2 is arranged above the second drive motor M2. The first drive motor M1 is electrically connected to the first inverter INV1, and the second drive motor M2 is electrically connected to the second inverter INV2. The first power transmission mechanism 50L and the second power transmission mechanism 50R are mechanically connected to the first drive motor M1 and the second drive motor M2, respectively.

[0053] The charging inlet 6 is disposed on the right side surface of the vehicle body 12. The charging inlet 6 is configured to be connected to an external DC power source 7 (for example, a charging station) via a power cable 8.

[0054] Reference Figure 5 , the detailed structure of the driving device 20 is described. Figure 5 yes Figure 4 The drive device 20 is a cross-sectional view taken along the line VV of FIG.

[0055] The first drive motor M1 of the drive device 20 includes a first motor housing 32L, a first motor bearing 33L, a first rotor 34L, a first stator 35L, and a first temperature sensor 39L. The first motor housing 32L accommodates the first rotor 34L, the first stator 35L, and the first temperature sensor 39L. The first rotor 34L has a first permanent magnet 36L. The first stator 35L is opposed to the first rotor 34L from the radially outer side. The outer periphery of the first stator 35L is formed by a U-phase winding 35U, a V-phase winding 35V, and a W-phase winding 35W (see FIG. 1 ). Figure 1 ) is covered. The first temperature sensor 39L is fixed to the left end surface of the first stator 35L. The first temperature sensor 39L detects the motor temperature T1 of the first drive motor M1 and sends it to the motor control device 5. In addition, in a modified example, the first temperature sensor 39L can also be fixed to the inner wall of the first motor housing 32L, for example. The first motor bearing 33L is, for example, a ball bearing. The first motor bearing 33L rotates the first motor shaft 51L by rolling the ball along the inner track wheel.

[0056] As described above, the second drive motor M2 has the same structure as the first drive motor M1. Therefore, the second drive motor M2 is the same as the first drive motor M1, and includes a second motor housing 32R, a second motor bearing 33R, a second rotor 34R having a second permanent magnet 36R, a second stator 35R, and a second temperature sensor 39R. The second motor bearing 33R rotates the second motor shaft 51R. The second temperature sensor 39R detects the motor temperature T2 of the second drive motor M2 and transmits it to the motor control device 5.

[0057] The first power transmission mechanism 50L transmits the power of the first drive motor M1 to the first drive shaft 14L. The first drive shaft 14L is connected to the front wheel 4L. The first power transmission mechanism 50L includes a plurality of bearings 53L, 56L, 58L, a plurality of gears 54L, 57L, 60L, 61L, 62L, and a plurality of shafts 55L, 59L. The first power transmission mechanism 50L, for example, uses a plurality of gears 54L, 57L, 60L, 61L, 62L to reduce the rotation speed of the first drive motor M1 and drives the first drive shaft 14L. In addition, the first power transmission mechanism 50L further includes a parking gear 70.

[0058] The second power transmission mechanism 50R transmits the power of the second drive motor M2 to the second drive shaft 14R. The second power transmission mechanism 50R has a structure that is bilaterally symmetrical with the first power transmission mechanism 50L described above. Therefore, the second power transmission mechanism 50R includes a plurality of bearings 53R, 56R, 58R, a plurality of gears 54R, 57R, 60R, 61R, 62R, and a plurality of shafts 55R, 59R. The second power transmission mechanism 50R, for example, utilizes a plurality of gears 54R, 57R, 60R, 61R, 62R, etc. to reduce the rotation speed of the second drive motor M2 and rotate the second drive shaft 14R.

[0059] [Example 3]

[0060] The third embodiment is different from the second embodiment in that the driving wheels driven by the first driving motor M1 and the second driving motor M2 are different. The common components in the third embodiment and the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Figure 6 Detailed description of the drawings is given in FIG. 1 , which is a block diagram of an electric vehicle 301 according to the third embodiment. Figure 6 is with Figure 4 Same attached pictures.

[0061] The drive device 20F includes a first drive motor M1, a first inverter INV1, and a first power transmission mechanism 50F. The first power transmission mechanism 50F transmits the power of the first drive motor M1 to the front wheels 4L and 4R via the first drive shaft 14.

[0062] The drive device 20B includes a second drive motor M2 , a second inverter INV2 , and a second power transmission mechanism 50B. The second power transmission mechanism 50B transmits the power of the second drive motor M2 to the rear wheels 5L and 5R via the second drive shaft 15 .

[0063] In the electric vehicle 301 of the third embodiment, it is also possible to execute Figure 2 The warm-up process described in the above is performed, so the same effect as that of the electric vehicle 1 of the first embodiment can be obtained.

[0064] The above detailed description of the implementation methods is provided, but these are merely examples and do not limit the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or the drawings exert technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology exemplified in this specification or the drawings achieves multiple purposes at the same time, and achieving one of the purposes itself has technical usefulness.

[0065] (Variation Example)

[0066] In the process of energizing the d-axis current (step S6), the motor control device 5 can also control the magnitude of the d-axis current energized to the second drive motor M2 according to the temperature difference calculated in step S2. For example, it can also be configured so that the greater the temperature difference, the greater the value of the d-axis current. At this time, the value of the d-axis current can also be proportional to the temperature difference. As a specific example, the value of the d-axis current can also be calculated by multiplying the temperature difference by a prescribed conversion value. Thus, the greater the temperature difference, the greater the value of the d-axis current can be, and thus the heat generated by the second drive motor M2 can be increased. Therefore, the warm-up process can be performed with good energy efficiency.

Claims

1. A driving device is a driving device for an electric vehicle having a battery, wherein: The driving device comprises: a first motor and a second motor electrically connected to the battery and driving at least one driving wheel of the electric vehicle; and a control device for controlling the current flowing to the first motor and the current flowing to the second motor respectively; The control device is configured to execute: a charging process of supplying electric power from an external power source to a battery via a neutral point of the first motor; and A energizing process, in which a d-axis current is supplied to the second motor in the charging process.

2. The driving device according to claim 1, wherein: The control device executes the energization process when a temperature difference between the first motor and the second motor is equal to or greater than a predetermined value during the charging process.

3. The driving device according to claim 2, wherein: The temperature difference is a difference between a magnet temperature of a rotor of the first motor and a magnet temperature of a rotor of the second motor.

4. The driving device according to any one of claims 1 to 3, wherein: The control device controls the magnitude of the d-axis current supplied to the second motor according to a temperature difference between the first motor and the second motor.

5. The driving device according to any one of claims 1 to 4, wherein: The control device is configured to further perform: a first estimating process of estimating a charging time required to complete charging of the battery through the charging process; and a second estimation process of estimating a required temperature rise time required for causing the temperature difference between the first motor and the second motor to fall below a predetermined value through the energization process; The control device starts the energization process in response to the time required for charging being reduced to be equal to or less than the time required for temperature increase.

6. The driving device according to claim 5, wherein: The control device is configured to execute a process of monitoring the temperature difference during the charging process. The first estimation process and the second estimation process are executed in response to the temperature difference becoming equal to or larger than the predetermined value.

7. The driving device according to any one of claims 1 to 6, wherein: The driving wheels are left and right wheels, The first motor drives one of the left wheel and the right wheel, and the second motor drives the other of the left wheel and the right wheel.

8. The driving device according to any one of claims 1 to 6, wherein: The driving wheels are the front wheels and the rear wheels of the electric vehicle, The first motor drives one of the front wheel and the rear wheel, and the second motor drives the other of the front wheel and the rear wheel.

9. The driving device according to any one of claims 1 to 8, wherein: further comprising an inverter circuit having a plurality of switching elements and electrically connected between the battery and the first motor, The control device controls the plurality of switching elements during the charging process, thereby causing the inverter circuit to function as a boost circuit together with the plurality of windings of the first motor.

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