Drive device

Abstract

The invention provides a drive device mounted on a vehicle. This drive device is provided with: a first electric motor that has a multi-phase coil and rotates drive wheels of a vehicle; a rotation prohibiting device that prohibits rotation of the drive wheel by the first electric motor; and a processor that controls a current supplied to the first electric motor. The processor executes a temperature raising process for raising the temperature of the multi-phase coils of the first electric motor by applying a current to the multi-phase coils. In the temperature raising process, the rotation prohibiting device prohibits the rotation of the drive wheel, and a q-axis current is included in a current supplied to the multi-phase coil.

Description

Technical Field

[0001] The present disclosure relates to a drive device, and more particularly to a drive device including an electric motor having multi-phase coils. Background Art

[0002] Japanese Patent Application Laid-Open No. 2009-118659 discloses a vehicle including a motor generator having three-phase coils.

[0003] In electric generators, such as those described in Japanese Patent Application Laid-Open No. 2009-118659, coil temperatures are sometimes increased. However, when heating the multi-phase coils, temperature differences between the phases may occur, and the electric generator may not exhibit desired magnetic properties. The present disclosure provides technology for reducing temperature differences between the phases of the coils when heating the multi-phase coils of an electric motor. Summary of the Invention

[0004] According to one embodiment of the present disclosure, a drive device mounted on a vehicle includes: a first electric motor having multi-phase coils and rotating the drive wheels of the vehicle; a rotation inhibiting device configured to inhibit rotation of the drive wheels by the first electric motor; and a processor configured to control the current supplied to the first electric motor. The processor is configured to perform a temperature increase process for increasing the temperature of the multi-phase coils of the first electric motor by supplying current to the multi-phase coils. During the temperature increase process, the rotation inhibiting device inhibits rotation of the drive wheels, and the current supplied to the multi-phase coils includes a q-axis current.

[0005] In the aforementioned drive device, while the rotation inhibiting device inhibits rotation of the drive wheel, a current including a q-axis current is passed through the multi-phase coils of the first electric motor. This allows the rotation of the drive wheel to be suppressed and the multi-phase coils to be heated, even when the q-axis current is causing the first electric motor to generate torque. By allowing the q-axis current to flow, the multi-phase coils of the first electric motor can be heated independently regardless of the rotor's rotational position. This reduces temperature differences between the coils of each phase when heating the multi-phase coils.

[0006] For example, a comparative example is also considered in which the temperature of the multi-phase coils of the first electric motor is increased by passing a current containing only the d-axis current through the multi-phase coils. This comparative example can suppress the generation of torque in the first electric motor while increasing the temperature of the multi-phase coils of the first electric motor. However, in this comparative example, different currents may be continuously passed through the multi-phase coils. In this case, the current amounts passed through the multi-phase coils differ. As a result, the heat generated by the multi-phase coils is not uniformized, and temperature differences may occur between the multi-phase coils. If temperature differences occur between the multi-phase coils, the first electric motor may not exhibit the desired magnetic properties. In the drive device disclosed herein, since currents containing the q-axis current are passed through the multi-phase coils of the first electric motor, the current amounts passed through the multi-phase coils can be more uniform than in the comparative example. This allows the multi-phase coils of the first electric motor to be appropriately heated.

[0007] Hereinafter, the details of the present disclosure will be described. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Features, advantages, and technical and industrial significance of embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals represent like elements, and wherein

[0009] Figure 1 A block diagram showing an electric vehicle 10 including a drive device 20 according to a first embodiment.

[0010] Figure 2 express Figure 1 Cross-sectional view along line II-II.

[0011] Figure 3 A circuit diagram of the drive device 20 is shown.

[0012] Figure 4 A flowchart showing a process executed by the control device 90 of the drive device 20 . DETAILED DESCRIPTION

[0013] The multi-phase coils may include three-phase coils. However, in other embodiments, the multi-phase coils may include two-phase coils.

[0014] The rotation preventing device may include a locking member configured to mechanically lock an axle connected to the drive wheel.

[0015] According to this configuration, the temperature raising process can be performed in a state where the rotation of the drive wheel is reliably prohibited by the locking member.

[0016] The processor may execute the temperature raising process while the vehicle is stopped.

[0017] According to this configuration, since the rotation prohibiting device prohibits the rotation of the drive wheels while the vehicle is stopped, the temperature raising process can be performed without affecting the running of the vehicle.

[0018] The drive device may further include a second electric motor having a multi-phase coil and configured to rotate the drive wheels of the vehicle. However, in other embodiments, the drive device may not include a second electric motor. Furthermore, the second electric motor may drive the same drive wheels as the first electric motor, or a different drive wheel.

[0019] The first and second electric motors may rotate a common drive shaft. However, in other embodiments, for example, the first electric motor may rotate a drive shaft connected to the front wheels of the vehicle, while the second electric motor may rotate a drive shaft connected to the rear wheels of the vehicle. In other words, the first and second electric motors may rotate different drive shafts.

[0020] The drive device may further include a second power conversion device electrically connected to the second electric motor. In this case, the second electric motor and the second power conversion device may constitute a charging circuit configured to supply power from an external power supply to the vehicle's battery via the neutral point of the second electric motor, and the processor may be configured to execute the temperature increase process based on charging of the battery by the charging circuit.

[0021] When the charging circuit charges the battery, the temperature of the second electric motor rises. With this configuration, the temperature of the first electric motor is raised by the temperature increase process in response to the charging circuit charging the battery, thereby reducing the temperature difference between the second electric motor and the first electric motor.

[0022] The processor may be configured to execute the temperature raising process during at least a portion of a charging period in which the battery is charged by the charging circuit.

[0023] The temperature of the second electric motor increases during the charging period when the charging circuit is charging the battery. With this configuration, the temperature of the first electric motor is increased by the temperature increase process during at least a portion of the battery charging period, thereby reducing the temperature difference between the second electric motor and the first electric motor.

[0024] The processor may be configured to determine a timing for starting the temperature raising process based on a scheduled start time of use of the vehicle.

[0025] For example, if the heating process is started without regard to the start time of use, the heating process may be performed for an unnecessarily long time, causing excessive current to flow through the coils of multiple phases. With this structure, the excessive current flow through the coils of multiple phases can be suppressed, thereby enabling energy-efficient heating.

[0026] The processor may be configured to determine a timing to terminate execution of the temperature raising process based on a scheduled start time of use of the vehicle.

[0027] For example, if the heating process is terminated regardless of the start time of use, the heating process may be performed for an unnecessarily long time, resulting in excessive current flowing into the coils of multiple phases. With this structure, the excessive current flowing into the coils of multiple phases can be suppressed, thereby enabling energy-efficient heating.

[0028] The processor may be configured to change the magnitude of the current supplied to the multi-phase coils of the first electric motor according to a temperature difference between the first electric motor and the second electric motor.

[0029] With this configuration, for example, when the temperature difference between the first electric motor and the second electric motor is small, the magnitude of the current flowing through the multi-phase coils can be reduced, thereby enabling energy-efficient temperature increase.

[0030] The vehicle may further include a heat medium circuit configured to circulate a heat medium. In this case, during the temperature increase process, the heat medium circuit may circulate the heat medium at least between the first electric motor and a battery of the vehicle.

[0031] According to this configuration, the temperature of the vehicle battery can be increased by utilizing the heat of the first electric motor generated by the temperature increase process.

[0032] (Example)

[0033] Figure 1 1 is a block diagram showing an electric vehicle 10 equipped with the drive device 20 of the first embodiment as viewed from above. In this specification, the front of the electric vehicle 10 (i.e., Figure 1 The left side of the electric vehicle 10 (i.e., Figure 1The left side of the paper) is simply represented as "left", and the opposite side is simply represented as "right". In addition, the upper side of the electric vehicle 10 (ie, Figure 1 The front side of the paper (the direction of the vehicle) is simply represented as "upper," and the opposite side is simply represented as "lower." Furthermore, the term "electric vehicle" in this specification includes, for example, rechargeable electric vehicles charged by an external power source, fuel cell vehicles powered by fuel cells, and hybrid vehicles that also include an engine.

[0034] In addition to a drive unit 20, the electric vehicle 10 includes a vehicle body 2, a battery pack 3, a pair of left and right front wheels 4L, 4R, a pair of left and right rear wheels 5L, 5R, a charging inlet 6, a parking brake 9, a radiator 12, and a radiator thermal circuit 16. The drive unit 20 includes a first electric motor 30L, a second electric motor 30R, a first inverter 40L, a second inverter 40R, a first power transmission mechanism 50L, and a second power transmission mechanism 50R. Hereinafter, "a pair of left and right wheels" may be simply referred to as "one pair."

[0035] The drive device 20 supplies power from the battery pack 3 to the electric motors 30L and 30R, thereby driving the pair of front wheels 4L and 4R. This drives the electric vehicle 10. Specifically, the pair of front wheels 4L and 4R serve as the drive wheels of the electric vehicle 10. In a modified embodiment, the pair of rear wheels 5L and 5R may serve as the drive wheels of the electric vehicle 10, or both the pair of front wheels 4L and 4R and the pair of rear wheels 5L and 5R may serve as the drive wheels of the electric vehicle 10.

[0036] The first electric motor 30L and the second electric motor 30R are arranged symmetrically with respect to the center line C1 in the left-right direction of the electric vehicle 10, and have the same structure as each other. The first electric motor 30L is located to the left of the center line C1, and the second electric motor 30R is located to the right of the center line C1. The first converter 40L is arranged above the first electric motor 30L, and the second converter 40R is arranged above the second electric motor 30R. The first electric motor 30L and the first converter 40L are electrically connected to each other, and the second electric motor 30R and the second converter 40R are electrically connected to each other. The power transmission mechanisms 50L and 50R are mechanically connected to the electric motors 30L and 30R, respectively. For details on the structure of each power transmission mechanism 50L and 50R, refer to Figure 2 To be described later.

[0037] The charging inlet 6 is located on the right side of the vehicle body 2 . The charging inlet 6 is connected to an external power source 7 (e.g., a charging station) via a power cable 8 . When the charging inlet 6 is connected to the external power source 7 , charging power from the external power source 7 is supplied to the battery pack 3 .

[0038] The radiator 12 is located at the front end of the vehicle body 2 of the electric vehicle 10. The radiator 12 performs heat exchange between a heat medium (e.g., antifreeze or water) circulating in the radiator's heat circuit 16 and the outside air. The radiator 12 cools the heat medium using, for example, airflow entering the vehicle body 2 while the electric vehicle 10 is traveling. While the electric vehicle 10 is traveling, the heat medium functions as a refrigerant, for example, to cool the electric motors 30L and 30R. Furthermore, as described in detail later, the heat medium also functions at low temperatures, for example, to heat the battery pack 3.

[0039] The radiator thermal circuit 16 includes a radiator pump 17, a first pipe 18L, a second pipe 19L, a third pipe 18R, and a fourth pipe 19R. The first pipe 18L connects the radiator 12 and the first electric motor 30L. The second pipe 19L connects the first electric motor 30L and the battery pack 3. Similarly, the third pipe 18R connects the radiator 12 and the second electric motor 30R, and the fourth pipe 19R connects the second electric motor 30R and the battery pack 3. The radiator pump 17 pumps heat medium through the radiator thermal circuit 16. In this embodiment, the heat medium circulates through the radiator pump 17 in the order of the first pipe 18L, the first electric motor 30L, the second pipe 19L, the battery pack 3, the third pipe 18R, the second electric motor 30R, the fourth pipe 19R, and the radiator 12.

[0040] Reference Figure 2 The detailed structure of the drive device 20 will be described. The drive device 20 includes, in addition to the aforementioned electric motors 30L and 30R, a control device 90. The control device 90 is a computer including a CPU, and is configured to communicate with, for example, the electric motors 30L and 30R, the parking brake 9, and the radiator pump 17, thereby controlling the operation of these devices.

[0041] The first electric motor 30L 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 houses 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 faces the first rotor 34L from the radially outer side of the first rotor 34L. The outer periphery of the first stator 35L is provided with a U-phase coil 35U, a V-phase coil 35V, and a W-phase coil 35W (see FIG. 1 ). Figure 3) and is covered. The coils 35U, 35V and 35W of each phase are arranged along the circumferential direction of the first stator 35L. The first temperature sensor 39L is fixed to the left end face of the first stator 35L. The first temperature sensor 39L detects the temperature T1 of the first electric motor 30L and sends it to the control device 90. 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 raceway. The other bearings are also ball bearings. In a modified example, each bearing can also be replaced by a roller bearing instead of a ball bearing.

[0042] As described above, the second electric motor 30R has the same structure as the first electric motor 30L. Therefore, like the first electric motor 30L, the second electric motor 30R includes a second motor housing 32R, a second motor bearing 33R, a second rotor 34R having second permanent magnets 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 temperature T2 of the second electric motor 30R and transmits the detected temperature to the control device 90.

[0043] The first power transmission mechanism 50L transmits the power of the first electric motor 30L to the drive shaft 14. The drive shaft 14 connects a pair of front wheels 4L and 4R to each other. The first power transmission mechanism 50L includes: a plurality of bearings 53L, 56L, 58L; a plurality of gears 54L, 57L, 61L, 62L; and a plurality of shafts 55L, 59L. The first power transmission mechanism 50L, for example, utilizes a plurality of gears 54L, 57L, 61L, 62L, etc. to reduce the rotation speed of the first electric motor 30L and drive the drive shaft 14. In addition, the first power transmission mechanism 50L also includes a parking gear 70. The parking gear 70 is adjusted according to the parking brake 9 (refer to Figure 1 ) is operated, the parking lock member (not shown) engages, thereby stopping the rotation of the first motor shaft 51L. Specifically, the parking gear 70 locks the drive shaft 14 connected to the front wheels 4L and 4R, thereby prohibiting the rotation of the front wheels 4L and 4R. In response to the user's operation, the parking brake 9 transmits an on signal S1 to the control device 90 indicating that the parking brake is in operation.

[0044] The second power transmission mechanism 50R transmits the power of the second electric motor 30R to the drive shaft 14. The second power transmission mechanism 50R has a bilaterally symmetrical structure with the first power transmission mechanism 50L. Therefore, the second power transmission mechanism 50R includes a plurality of bearings 53R, 56R, and 58R; a plurality of gears 54R, 57R, 61R, and 62R; and a plurality of shafts 55R and 59R. The second power transmission mechanism 50R reduces the rotational speed of the second electric motor 30R using, for example, the gears 54R, 57R, 61R, and 62R, thereby rotating the drive shaft 14.

[0045] like Figure 1 As shown, in this embodiment, the drive shaft 14 connects a pair of front wheels 4L and 4R. Therefore, the pair of front wheels 4L and 4R are driven by two electric motors 30L and 30R. Furthermore, in a modified embodiment, the drive shaft 14 may be separated at the center of the left-right direction of the electric vehicle 10. That is, the pair of front wheels 4L and 4R may be independently driven by the electric motors 30L and 30R, respectively.

[0046] Reference Figure 3 The electrical circuit of the drive device 20 will be described. The first electric motor 30L is a three-phase motor including a U-phase coil 35U, a V-phase coil 35V, and a W-phase coil 35W. One end of the U-phase coil 35U, the V-phase coil 35V, and the W-phase coil 35W is connected to the neutral point NP1. The other end of the U-phase coil 35U of the first electric motor 30L is connected to the U-phase arm 42U of the first inverter 40L. Similarly, the other end of the V-phase coil 35V of the first electric motor 30L is connected to the V-phase arm 42V of the first inverter 40L, and the other end of the W-phase coil 35W is connected to the W-phase arm 42W. In this way, the first inverter 40L and the first electric motor 30L are electrically connected.

[0047] Similarly, the second electric motor 30R is also a three-phase motor. One end of the U-phase coil 35U, V-phase coil 35V, and W-phase coil 35W of the second electric motor 30R is connected to the neutral point NP2. The other end of the U-phase coil 35U of the second electric motor 30R is connected to the U-phase arm 42U of the second inverter 40R. Similarly, the other end of the V-phase coil 35V of the second electric motor 30R is connected to the V-phase arm 42V of the second inverter 40R, and the other end of the W-phase coil 35W is connected to the W-phase arm 42W. In this way, the second inverter 40R and the second electric motor 30R are electrically connected.

[0048] like Figure 3As shown, the drive device 20 further includes a charging circuit 11. The charging circuit 11 is a circuit for supplying DC charging power from the external power supply 7 to the battery pack 3. In the charging circuit 11, one terminal of the charging inlet 6 is connected to the positive terminal of the battery pack 3 via the neutral point NP2 of the second electric motor 30R and the second inverter 40R. In other words, the charging circuit 11 supplies charging power from the external power supply 7 to the neutral point NP2 of the second electric motor 30R. Furthermore, the other terminal of the charging inlet 6 is connected to the negative terminal of the battery pack 3 via the second inverter 40R. The charging circuit 11 supplies charging power to the battery pack 3 via the neutral point NP2 of the second electric motor 30R. Thus, the second electric motor 30R and the second inverter 40R function as three boosting circuits connected in parallel between the charging inlet 6 and the battery pack 3. Consequently, the drive device 20 can boost the output voltage of the external power supply 7 using the second electric motor 30R and the second inverter 40R. This allows for rapid charging even when the output voltage of the external power supply 7 is lower than the voltage of the battery pack 3. Furthermore, one terminal of the charging inlet 6 is directly connected to the positive terminal of the battery pack 3 via the switch 13. When the output voltage of the external power supply 7 is equal to the voltage of the battery pack 3, the charging circuit 11 can bypass the output voltage of the external power supply 7 to the neutral point NP2 of the second electric motor 30R by turning on the switch 13. Although not shown, the charging circuit 11 also includes a charging unit including a relay and a capacitor. This charging unit is connected to the neutral point NP2 and the second inverter 40R.

[0049] In this embodiment, the charging inlet 6 is connected to the external power source 7. While charging power from the external power source 7 is being supplied to the neutral point NP2 of the second electric motor 30R, current flows through the coils 35U, 35V, and 35W of each phase of the second electric motor 30R. As a result, the coils 35U, 35V, and 35W of each phase generate heat, raising the temperature T2 of the second electric motor 30R. On the other hand, even when the charging inlet 6 is connected to the external power source 7, current does not flow through the coils 35U, 35V, and 35W of each phase of the first electric motor 30L, and thus the temperature T1 of the first electric motor 30L does not rise. Therefore, while charging power from the external power source 7 is being supplied to the neutral point NP2 of the second electric motor 30R, the temperature difference between the electric motors 30L and 30R increases. In this case, the output torque of the electric motors 30L and 30R becomes unbalanced, potentially reducing the driving stability of the electric vehicle 10.

[0050] Reference Figure 4The temperature increase setting process executed by the control device 90 of the drive device 20 will be described. The temperature increase setting process is a process for generating heat in the coils 35U, 35V, and 35W of each phase of the first electric motor 30L by passing a current, including a q-axis current, through the coils 35U, 35V, and 35W. The control device 90 initiates the temperature increase setting process upon connection of the charging inlet 6 to the external power supply 7. Specifically, the control device 90 executes the temperature increase process in response to charging of the battery pack 3 by the charging circuit 11. This prevents the temperature difference between the electric motors 30L and 30R from increasing due to charging of the battery pack 3.

[0051] In the temperature acquisition process S2 , the control device 90 acquires the temperature T1 of the first electric motor 30L from the first temperature sensor 39L and acquires the temperature T2 of the second electric motor 30R from the second temperature sensor 39R.

[0052] In the temperature rise determination process S4, the control device 90 calculates the temperature difference T2-T1 based on the temperature T1 and the temperature T2 obtained by the temperature acquisition process S2, and compares the temperature difference with the pre-stored threshold temperature difference Tth. Here, the threshold temperature difference Tth is a threshold value for determining whether the temperature difference T2-T1 causes a decrease in the stability of the drive device 20 during driving. The threshold temperature difference Tth is determined based on the size, output torque, etc. of each electric motor 30L, 30R, but can be changed by the user afterwards. When the temperature difference T2-T1 is less than the threshold temperature difference Tth (No in the temperature rise determination process S4), even if the temperature rise process of the coils 35U, 35V, 35W of each phase of the first electric motor 30L is not performed, the output torque of each electric motor 30L, 30R is maintained relatively uniform. Therefore, the drive device 20 can be driven stably. If the judgment is No in the temperature rise determination process S4, the control device 90 ends. Figure 4 Thus, regardless of whether the temperature difference T2-T1 is less than the threshold temperature difference Tth and the electric motors 30L and 30R can be driven in a well-balanced manner, unnecessary temperature increase processing can be suppressed. On the other hand, if the temperature difference T2-T1 is greater than the threshold temperature difference Tth (YES in the temperature increase determination process S4), the output torque of the electric motors 30L and 30R is unbalanced, and the stability of the electric motors 30L and 30R during driving may be reduced. Therefore, the control device 90 determines that temperature increase processing is necessary and enters the current adjustment process S6.

[0053] In the current adjustment process S6, the control device 90 adjusts the magnitude of the current flowing through the coils 35U, 35V, and 35W of each phase of the first electric motor 30L during the temperature increase process based on the temperature difference T2-T1 calculated by the temperature increase determination process S4. Specifically, the control device 90 multiplies the temperature difference T2-T1 by a predetermined conversion value to calculate the value of the current flowing. Therefore, the larger the temperature difference T2-T1, the larger the value of the current flowing. That is, the value of the current flowing is proportional to the temperature difference T2-T1. For example, when the temperature difference T2-T1 is small, the magnitude of the current flowing can be reduced compared to when the temperature difference T2-T1 is large. In this way, the temperature increase process can be performed energy-efficiently. In the following, the current flowing after adjustment by the current adjustment process S6 is sometimes recorded as "adjusted current."

[0054] In the time calculation process S10, the control device 90 calculates the use start time. The use start time is the time when the charging of the battery pack 3 is predicted to be completed and the electric vehicle 10 starts to travel again after the charging of the battery pack 3 starts. The control device 90 stores, for example, the charging amount per unit time and the performance value of the time from the end of charging to the start of travel. Therefore, the control device 90 first calculates the charging time required until the charging is completed based on the power remaining in the battery pack 3 at the current moment. The control device 90 adds the calculated charging time to the predicted time from the end of charging to the resumption of travel to calculate the use start time. The predicted time from the end of charging to the resumption of travel can be, for example, the average of the performance values or the shortest performance value. In other variations, the predicted time can also be an arbitrary time input by the user.

[0055] In the first monitoring process S12, the control device 90 monitors the arrival of the temperature rise start time. The temperature rise start time indicates when energization begins to be applied to the coils 35U, 35V, and 35W of each phase of the first electric motor 30L. The temperature rise start time is determined based on the use start time calculated in the time calculation process S10 and the adjusted current calculated in the current adjustment process S6. Specifically, the temperature rise start time is calculated by subtracting the temperature rise time required to reduce the current temperature difference T2-T1 to less than the threshold temperature difference Tth when the adjusted current is applied to the coils 35U, 35V, and 35W of each phase of the first electric motor 30L from the use start time calculated in the time calculation process S10. For example, if the difference between the temperature difference T2-T1 and the threshold temperature difference Tth is large, a relatively early temperature rise start time is set. As a result, the temperature T1 rises relatively early, and the temperature difference T2-T1 can be reliably kept below the threshold temperature difference Tth until the use start time is reached.

[0056] On the other hand, when the difference between the temperature difference T2 - T1 and the threshold temperature difference Tth is small, a delayed temperature rise start time is set compared to when the difference between the temperature difference T2 - T1 and the threshold temperature difference Tth is large. The control device 90 repeatedly executes the first monitoring process S12 until the temperature rise start time is reached. This prevents the first electric motor 30L from being energized for an unnecessary long period of time due to the temperature rise process being initiated before the temperature rise start time. By determining the timing for starting energization of the coils 35U, 35V, and 35W of each phase of the first electric motor 30L corresponding to the start of use of the electric vehicle 10, the temperature of the first electric motor 30L can be raised energy efficiently. If the temperature rise start time is reached, the control device 90 determines yes in the first monitoring process S12 and proceeds to the braking determination process S20.

[0057] In the brake determination process S20, the control device 90 determines whether the parking brake 9 is in operation. Specifically, the control device 90 determines whether it has received an on signal S1 from the parking brake 9. If the control device 90 has not received the on signal S1 (No in S20), the control device 90 proceeds to the brake operation process S22. If the control device 90 has received the on signal S1 (Yes in S20), the control device 90 proceeds to the energization process S24.

[0058] In the brake operation process S22, the control device 90 applies and activates the parking brake 9. This locks the drive shaft 14, preventing the electric vehicle 10 from running during the temperature increase process. After the brake operation process S22 is completed, the control device 90 proceeds to the power supply process S24.

[0059] In the energizing process S24, the control device 90 energizes the adjusted current calculated in the current adjusting process S6 to the first electric motor 30L. This generates heat in the coils 35U, 35V, and 35W of each phase of the first electric motor 30L, and increases the temperature T1 of the first electric motor 30L.

[0060] Furthermore, in pump operation processing S26, the control device 90 turns on and operates the radiator pump 17. The radiator pump 17 thereby circulates the heat medium through the radiator heat circuit 16. As a result, for example, the heat medium circulates between the first electric motor 30L and the battery pack 3. This allows heat generated in the coils 35U, 35V, and 35W of each phase of the first electric motor 30L to be supplied to the battery pack 3 via the heat medium. Consequently, the battery pack 3 can be heated.

[0061] In the second monitoring process S30, the control device 90 monitors whether the heating end time has been reached. The heating end time is a time indicating the timing of ending the energization of the coils 35U, 35V, and 35W of each phase of the first electric motor 30L. The heating end time is the time when the temperature difference T2-T1 becomes less than the threshold temperature difference Tth after the heating start time is reached (yes in the first monitoring process S12) and the energization of the first electric motor 30L is started in the energization process S24. It is a time determined based on the use start time calculated in the time calculation process S10. The control device 90 repeatedly executes the second monitoring process S30 until the heating end time is reached. When the heating end time is reached (yes in the second monitoring process S30), the energization end process S32 is entered.

[0062] In the energization termination process S32, the control device 90 terminates the energization of the first electric motor 30L. In this way, by terminating the energization at the temperature rise termination time corresponding to the temperature rise start time corresponding to the use start time, it is possible to prevent the first electric motor 30L from being energized for a long time unnecessarily. When the energization termination process S32 is terminated, the control device 90 terminates Figure 4 Temperature setting processing.

[0063] Effects of this embodiment

[0064] In the driving device 20 of this embodiment, when the parking gear 70 prohibits the rotation of the pair of front wheels 4L, 4R, a current including a q-axis current is supplied to the coils 35U, 35V, 35W of each phase of the first electric motor 30L. Figure 4 Power-on processing S24). Thus, even when the q-axis current is used to generate torque in the first electric motor 30L, the rotation of the pair of front wheels 4L and 4R can be suppressed, and the three-phase coils 35U, 35V, and 35W can be heated. Because power is permitted not only for the d-axis current but also for the q-axis current, the multi-phase coils 35U, 35V, and 35W of the first electric motor 30L can be heated independently regardless of the rotational position of the first rotor 34L. Thus, when heating the coils 35U, 35V, and 35W of each phase, the temperature difference between the coils 35U, 35V, and 35W of each phase can be reduced.

[0065] Correspondence

[0066] The parking gear 70 is an example of a “rotation prohibiting device” or a “locking member”. Figure 4 The energizing process S24 is an example of a “temperature raising process.” The second converter 40R is an example of a “second power conversion device.”

[0067] While the specific examples disclosed above have been described in detail, these are merely illustrative and do not limit the scope of the technical solutions. The techniques described in the technical solutions include various variations and modifications of the specific examples illustrated above. Modifications of the above-described embodiments are listed below.

[0068] Modification 1

[0069] The first electric motor 30L and the second electric motor 30R may include two-phase coils. In other modified examples, the first electric motor 30L and the second electric motor 30R may include four or more phase coils.

[0070] Modification 2

[0071] The gear 62L of the first power transmission mechanism 50L may also be configured to be able to cut off the drive shaft 14. In this case, the control device 90 may also be configured to be able to cut off the drive shaft 14. Figure 4 In the brake operation process S22, instead of turning on the parking brake 9, the gear 62L and the drive shaft 14 are disconnected. As a result, the rotation of the drive shaft 14 is prohibited. In this modification, the gear 62L is an example of a "rotation prohibition device".

[0072] Modification 3

[0073] The control device 90 may use the fact that the charging inlet 6 is connected to the external power supply 7 as a trigger and not execute the Figure 4 The control device 90 can also execute the temperature setting process according to the user's instructions. Figure 4 In this case, the control device 90 may also execute the process of the electric vehicle 10 while the electric vehicle 10 is traveling. Figure 4 processing.

[0074] Modification 4

[0075] The drive device 20 may not include the second electric motor 30R. The drive device 20 may include only the first electric motor 30L. In this case, the control device 90 may also be configured as follows: Figure 4 In the temperature acquisition process S2, the temperature of the coils 35U, 35V, and 35W of each phase of the first electric motor 30L is acquired. In this modified example, in the temperature increase determination process S4, the control device 90 may also execute the temperature increase process if the temperature difference between the coils 35U, 35V, and 35W of each phase exceeds a threshold value. In this case, in the current adjustment process S6, the control device 90 may also adjust the magnitude of the energized current so that the coil of the phase with the lowest temperature generates the most heat.

[0076] Modification 5

[0077] The second electric motor 30R and the second inverter 40R may not constitute the charging circuit 11. In this case, the control device 90 may also execute the control of both the first electric motor 30L and the second electric motor 30R. Figure 4 processing.

[0078] Modification 6

[0079] The control device 90 may not execute Figure 4 In this modification, for example, after the charging inlet 6 is connected to the external power supply 7, energization of the first electric motor 30L may be started after a predetermined time has passed.

[0080] Modification 7

[0081] The control device 90 may not execute Figure 4 In this modification, for example, the control device 90 may execute the energization end process S32 when the temperature difference T2 - T1 is smaller than the threshold temperature difference Tth.

[0082] Modification 8

[0083] The control device 90 may not execute Figure 4 In this case, the radiator heat circuit 16 of the electric vehicle 10 may not include the second pipe 19L and the fourth pipe 19R.

[0084] The technical elements described in this specification or drawings demonstrate their technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies exemplified in this specification or drawings are capable of simultaneously achieving multiple objectives, and achieving one of these objectives itself is technically useful.

Claims

1. A driving device mounted on a vehicle, characterized in that: Include: a first electric motor having a multi-phase coil and configured to rotate the drive wheels of the vehicle; a rotation prohibiting device configured to prohibit rotation of the drive wheel by the first electric motor; and a processor configured to control a current supplied to the first electric motor; in, The processor is configured to execute a temperature raising process for raising the temperature of the multi-phase coils of the first electric motor by supplying current to the multi-phase coils. In the temperature increase process, the rotation prohibiting device prohibits rotation of the drive wheel, and the current supplied to the multi-phase coils includes a q-axis current.

2. The driving device according to claim 1, characterized in that The multi-phase coil includes a three-phase coil.

3. The driving device according to claim 1, characterized in that The rotation preventing device includes a locking member configured to mechanically lock an axle connected to the drive wheel.

4. The driving device according to claim 1, characterized in that The processor executes the temperature raising process while the vehicle is stopped.

5. The driving device according to claim 1, characterized in that The vehicle further includes a second electric motor having multi-phase coils and configured to rotate the drive wheels of the vehicle.

6. The driving device according to claim 5, characterized in that The first electric motor and the second electric motor are configured to rotate a common drive shaft.

7. The driving device according to claim 5, characterized in that further comprising a second power conversion device electrically connected to the second electric motor, in, The second electric motor and the second power conversion device constitute a charging circuit, and the charging circuit is configured to supply power from an external power source to the battery of the vehicle via the neutral point of the second electric motor. The processor is configured to execute the temperature raising process based on charging of the battery by the charging circuit.

8. The driving device according to claim 7, characterized in that The processor is configured to execute the temperature raising process during at least a portion of a charging period in which the battery is charged by the charging circuit.

9. The driving device according to claim 7, characterized in that The processor is configured to determine a timing for starting the temperature raising process based on a scheduled start time of use of the vehicle.

10. The driving device according to claim 7, characterized in that The processor is configured to determine a timing to terminate execution of the temperature raising process based on a scheduled start time of use of the vehicle.

11. The driving device according to claim 5, characterized in that The processor is configured to change the magnitude of the current supplied to the multi-phase coils of the first electric motor according to a temperature difference between the first electric motor and the second electric motor.

12. The driving device according to claim 1, characterized in that The vehicle further includes a heat medium circuit configured to circulate a heat medium. In the temperature raising process, the heat medium circuit circulates the heat medium at least between the first electric motor and a battery of the vehicle.

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