Vehicle motor winding switching system, control device, vehicle motor control method, and computer program

Abstract

This coil switching system comprises a drive motor that drives a wheel of a vehicle, a control device that controls the drive motor, a power converter that converts DC power outputted from a battery to AC power and supplies the AC power to the drive motor, and a coil switching device that switches a connection state of a plurality coils in the drive motor between a first connection state and a second connection state, the control device including a torque control unit that changes the output torque of the drive motor by changing the alternating electric current outputted from the power converter at a prescribed speed change timing of the vehicle, and a switching control unit that causes the coil switching device to switch from the first connection state to the second connection state after the alternating electric current has changed.

Description

Technical Field

[0001] The present disclosure relates to a winding switching system for a vehicle motor, a control device, a method for controlling a vehicle motor, and a computer program. This application claims priority based on Japanese Application No. 2022-162243 filed on October 7, 2022, and incorporates all the contents described in the above Japanese application.

Background Art

[0002] Patent Document 1 discloses that in a vehicle that drives wheels by a drive motor such as an electric vehicle and a hybrid vehicle without a stepped transmission, torque fluctuation control is performed in which the torque of the drive motor is decreased by a set fluctuation amount and then increased, thereby producing a pseudo shift change.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A winding switching system for a vehicle motor according to an aspect of the present disclosure includes a drive motor that drives wheels of a vehicle, a control device that controls the drive motor, a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor, and a winding switching device that switches a connection state of a plurality of windings in the drive motor between a first connection state and a second connection state. The control device includes a torque control unit that changes an output torque of the drive motor by changing an alternating current output from the power converter at a predetermined shift timing of the vehicle, and a switching control unit that causes the winding switching device to switch from the first connection state to the second connection state after the alternating current changes.

[0005] This disclosure can be implemented not only as a winding switching system for a vehicle motor having the characteristic configuration described above, but also as a control device included in a vehicle motor winding switching system, or as a control method for a vehicle motor using characteristic processing in the control device as steps. This disclosure can be implemented as a computer program that makes a computer function as a control device, or as a semiconductor integrated circuit in part or all of the control device. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 shows an example of the configuration of a winding switching system according to the first embodiment. [Figure 2] Figure 2 is a block diagram showing an example of the hardware configuration of a control device. [Figure 3] Figure 3 is a circuit diagram showing an example of the configuration of a winding switching device according to the first embodiment. [Figure 4] Figure 4 is a timing chart showing an example of the motor winding switching timing in the winding switching system according to the first embodiment. [Figure 5] Figure 5 is a flowchart showing an example of an electrical shift-up process by the control device according to the first embodiment. [Figure 6] Figure 6 is a flowchart showing an example of electrical shift-down processing by the control device according to the first embodiment. [Figure 7] Figure 7 is a circuit diagram showing an example of the configuration of a winding switching device according to the second embodiment. [Figure 8] Figure 8 is a timing chart showing an example of the motor winding switching timing in the winding switching system according to the third embodiment. [Figure 9] Figure 9 is a timing chart showing an example of the motor winding switching timing in the winding switching system according to the fourth embodiment. [Figure 10]Figure 10 is a timing chart showing an example of pseudo-speed change control processing in the winding switching system according to the fifth embodiment. [Figure 11] Figure 11 is a flowchart showing an example of simulated gear shifting processing by the control device according to the fifth embodiment. [Figure 12] Figure 12 is a functional block diagram showing an example of the functions of the control device according to the sixth embodiment. [Figure 13] Figure 13 is a flowchart showing an example of a forced shift-up determination process by the control device according to the sixth embodiment. [Figure 14] Figure 14 is a flowchart showing an example of the forced shift-down determination process by the control device according to the sixth embodiment. [Modes for carrying out the invention]

[0007] <Issues this disclosure aims to address> The simulated gear change in the vehicle disclosed in Patent Document 1 is achieved at the expense of the vehicle's driving performance, rather than by actually performing a gear change using a stepped transmission.

[0008] <Effects of this disclosure> According to this disclosure, it is possible to efficiently utilize the performance of the electric vehicle's drive motor while providing the driver with a gear shifting sensation similar to that of a stepped transmission.

[0009] <Summary of the embodiments of this disclosure> The embodiments of this disclosure are outlined below.

[0010] (1) The winding switching system for a vehicle motor according to this embodiment includes a drive motor that drives the wheels of a vehicle, a control device that controls the drive motor, a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor, and a winding switching device that switches the connection state of a plurality of windings in the drive motor between a first connection state and a second connection state. The control device includes a torque control unit that changes the output torque of the drive motor by changing the AC current output from the power converter at a predetermined shift timing of the vehicle, and a switching control unit that, after the AC current has changed, causes the winding switching device to switch from the first connection state to the second connection state. As a result, the connection state of the drive motor windings is switched from the first connection state to the second connection state, and the performance of the drive motor can be efficiently utilized to achieve a shift equivalent to a shift by a mechanical transmission (hereinafter also referred to as "electrical shift"). Furthermore, by changing the output torque of the drive motor in conjunction with the switching of the connection state of the drive motor windings, the driver can be given a shifting sensation similar to that of a mechanical transmission.

[0011] (2) In (1) above, the torque control unit may reduce the output torque of the drive motor by reducing the AC current output from the power converter at the first shift timing, and the switching control unit may, after the AC current has decreased to or below the first target value, cause the winding switching device to switch from the first connection state to the second connection state. This makes it possible to achieve electrical shifting similar to shifting up by a mechanical transmission while the vehicle is accelerating or maintaining speed.

[0012] (3) In the above (2), the torque control unit reduces the output torque of the drive motor by reducing the alternating current output from the power converter at a second shift timing different from the first shift timing, and the switching control unit may cause the winding switching device to switch from the second connection state to the first connection state after the alternating current decreases to or below the first target value. Thereby, it is possible to realize an electric shift similar to a downshift by a mechanical transmission while the vehicle is accelerating or maintaining its speed.

[0013] (4) In the above (1), the torque control unit increases the output torque of the drive motor by increasing the alternating current output from the power converter at the first shift timing, and the switching control unit may cause the winding switching device to switch from the first connection state to the second connection state after the alternating current increases to or above a second target value. Thereby, it is possible to realize an electric shift similar to an upshift by a mechanical transmission while the drive motor is performing regenerative braking.

[0014] (5) In the above (4), the torque control unit increases the output torque of the drive motor by increasing the alternating current output from the power converter at a second shift timing different from the first shift timing, and the switching control unit may cause the winding switching device to switch from the second connection state to the first connection state after the alternating current increases to or above a second target value. Thereby, it is possible to realize an electric shift similar to a downshift by a mechanical transmission while the drive motor is performing regenerative braking.

[0015] (6) In any one of the above (1) to (5), the second connection state may be a connection state for the drive motor to output a lower torque than the first connection state at the same rotational speed. Thereby, it is possible to switch the connection state of the windings of the drive motor between the high-torque low-speed type first connection state and the low-torque high-speed type second connection state.

[0016] (7) In the above (6), when the connection state of the plurality of windings is the first connection state, the control device further includes a first determination unit that determines, as the first forced shift timing, the timing before the induced voltage generated in the winding exceeds the output voltage of the battery. The torque control unit changes the output torque of the drive motor by changing the alternating current output from the power converter at the first forced shift timing determined by the first determination unit. After the alternating current changes, the switching control unit may cause the winding switching device to switch from the first connection state to the second connection state. When the induced voltage generated in the winding exceeds the output voltage of the battery, it becomes impossible to change the current flowing through the winding to zero. When the connection state of the winding is switched by a relay while a current is flowing through the winding, the relay may be damaged. With the above configuration, when switching the connection state of the winding from the first connection state to the second connection state, the current flowing through the winding can be suppressed and the relay can be protected.

[0017] (8) In the above (7), the first determination unit may determine, as the first forced shift timing, the timing when a physical quantity related to the induced voltage exceeds a first threshold value corresponding to the output voltage of the battery. Thereby, using the physical quantity related to the induced voltage, the timing before the induced voltage exceeds the output voltage of the battery can be accurately determined.

[0018] (9) In the above (8), the physical quantity may be one of the voltage in the winding, the rotational speed of the drive motor, the current flowing through the winding, and the output torque of the drive motor. Thereby, the timing before the induced voltage exceeds the output voltage of the battery can be accurately determined by one of the voltage in the winding, the rotational speed of the motor, the current flowing through the winding, and the output torque of the motor, which can be easily detected by a sensor.

[0019] (10) In any one of (7) to (9) above, the control device may further include: a determination unit that determines whether the induced voltage of the windings exceeds the output voltage of the battery after the connection state of the windings is switched from the second connection state to the first connection state when the connection state of the plurality of windings is in the second connection state; and a prohibition unit that prohibits the switching control unit from switching the connection state of the windings when the determination unit determines that the induced voltage exceeds the output voltage of the battery. This prevents the induced voltage of the windings from exceeding the output voltage of the battery after the connection state of the windings is switched from the second connection state to the first connection state. Thus, the relay can be protected from damage.

[0020] (11) In any one of (7) to (10) above, the control device further includes a second determination unit that determines the timing after the induced voltage of the windings becomes less than or equal to the output voltage of the battery when the connection state of the plurality of windings is in the second connection state, the timing after the induced voltage of the windings is switched from the second connection state to the first connection state, as the second forced speed change timing, the torque control unit changes the output torque of the drive motor by changing the AC current output from the power converter at the second forced speed change timing determined by the second determination unit, and the switching control unit may cause the winding switching device to switch from the second connection state to the first connection state after the AC current has changed.

[0021] (12) In (11) above, the second determination unit may determine the timing at which the physical quantity relating to the induced voltage becomes less than or equal to a second threshold corresponding to the output voltage of the battery as the second forced shift timing. This makes it possible to accurately determine the timing after the induced voltage becomes less than or equal to the output voltage of the battery using the physical quantity relating to the induced voltage.

[0022] (13) In any one of (1) to (12) above, the winding switching system further comprises an input device for receiving a speed change instruction from the driver, and the speed change timing may be the timing at which the input device receives the speed change instruction from the driver. This allows the drive motor to perform an electrical speed change in accordance with the driver's speed change instruction.

[0023] (14) In any one of (1) to (12) above, the gear shift timing may be determined based on the rotational speed of the drive motor, the output torque, the acceleration instruction amount in the vehicle, and the braking instruction amount in the vehicle. This allows the drive motor to perform an electrical gear shift according to the timing determined by the rotational speed of the motor, the output torque, the acceleration instruction amount (amount of depression of the accelerator pedal), and the braking instruction amount (amount of depression of the brake pedal).

[0024] (15) In any one of (1) to (14) above, the torque control unit may gradually decrease or increase the effective current of the AC current output from the power converter from the gear shift timing. This allows for a smooth change in torque and provides the driver with a natural gear shifting sensation.

[0025] (16) In (15) above, the torque control unit may change the effective current in a ramp-like manner from the gear shift timing. This can give the driver a gear shift sensation in which the torque changes smoothly.

[0026] (17) In any one of (1) to (14) above, the torque control unit may change the effective current of the AC current output from the power converter in a step manner based on the gear shift timing. This can give the driver the sensation of a sudden change in torque during gear shifting.

[0027] (18) In any one of (1) to (17) above, the torque control unit may perform a pseudo-shift control process in which it decreases and then increases the AC current output from the power converter at a pseudo-shift timing different from the shift timing. As a result, the drive motor performs a pseudo-shift in addition to the electrical shift. Therefore, the driver can be given the sensation of shifting multiple gears.

[0028] (19) The control device according to this embodiment is a control device for controlling a drive motor that drives the wheels of a vehicle, and includes a torque control unit that changes the output torque of the drive motor by changing the AC current output from a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor at a predetermined shift timing of the vehicle, and a switching control unit that switches a winding switching device that switches the connection state of a plurality of windings in the drive motor from a first connection state to a second connection state after the AC current has changed. As a result, the connection state of the windings of the drive motor is switched from a first connection state to a second connection state, so that the performance of the drive motor can be efficiently utilized to achieve electrical speed change. Furthermore, by changing the output torque of the drive motor in conjunction with the switching of the connection state of the windings of the drive motor, the driver can be given a shifting sensation similar to that of a mechanical transmission.

[0029] (20) The vehicle motor control method according to this embodiment is a vehicle motor control method executed by a control device that controls a drive motor that drives the wheels of a vehicle, and includes the steps of changing the output torque of the drive motor by changing the AC current output from a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor at a predetermined shift timing of the vehicle, and causing a winding switching device that switches the connection state of a plurality of windings in the drive motor to switch from a first connection state to a second connection state after the AC current has changed. As a result, the connection state of the drive motor windings is switched from a first connection state to a second connection state, so that the performance of the drive motor can be efficiently utilized to achieve electrical speed change. Furthermore, by changing the output torque of the drive motor in conjunction with the switching of the connection state of the drive motor windings, the driver can be given a shifting sensation similar to that of a mechanical transmission.

[0030] (21) The computer program according to this embodiment is a computer program used by a control device that controls a drive motor that drives the wheels of a vehicle, and causes the computer to perform the following steps: to change the output torque of the drive motor by changing the AC current output from a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor at a predetermined shift timing of the vehicle; and to cause a winding switching device that switches the connection state of a plurality of windings in the drive motor to switch from a first connection state to a second connection state after the AC current has changed. As a result, the connection state of the drive motor windings is switched from a first connection state to a second connection state, so that the performance of the drive motor can be efficiently utilized to achieve electrical speed change. Furthermore, by changing the output torque of the drive motor in conjunction with the switching of the connection state of the drive motor windings, the driver can be given a shifting sensation similar to that of a mechanical transmission.

[0031] <Details of the embodiments of this disclosure> The embodiments of the present invention will be described in detail below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0032] [1. First Embodiment] [1-1. Winding Switching System] Figure 1 shows an example of the configuration of a winding switching system according to the first embodiment.

[0033] The winding switching system 10 is installed in electric vehicles, plug-in hybrid vehicles, and other motor-driven vehicles (hereinafter referred to as "electric vehicles"). The winding switching system 10 includes a motor 20, a power converter 30, a battery 40, a control device 50, and a winding switching device 100.

[0034] Motor 20 is a motor used for propulsion that generates the thrust of the electric vehicle. In other words, motor 20 is connected to the wheels 60 and is a drive motor that drives the wheels 60. Motor 20 is driven by three-phase AC power. An example of motor 20 is a permanent magnet synchronous motor.

[0035] Battery 40 is a battery that supplies power to drive the motor 20. Battery 40 is a rechargeable battery, such as a lithium-ion battery.

[0036] The power converter 30 is an inverter that converts DC power supplied from the battery 40 into three-phase AC power. The power converter 30 may also have a function to convert the three-phase AC power output by the motor 20 when it functions as a generator into DC power and charge the battery 40.

[0037] The power converter 30 includes U-phase, V-phase, and W-phase legs. The U-phase leg includes switches 31u and 32u, the V-phase leg includes switches 31v and 32v, and the W-phase leg includes switches 31w and 32w. By switching switches 31u, 32u, 31v, 32v, 31w, and 32w, DC power is converted into three-phase AC power. Switches 31u, 32u, 31v, 32v, 31w, and 32w are, for example, IGBTs (Insulated Gate Bipolar Transistors) or power MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors).

[0038] A power line 35u corresponding to the U phase extends from the U phase leg, a power line 35v corresponding to the V phase extends from the V phase leg, and a power line 35w corresponding to the W phase extends from the W phase leg. In the power converter 30, a current sensor 33u is provided on the power line 35u, a current sensor 33v is provided on the power line 35v, and a current sensor 33w is provided on the power line 35w. The current sensor 33u detects the current value of the U phase current Iu. The current sensor 33v detects the current value of the V phase current Iv. The current sensor 33w detects the current value of the W phase current Iw. The current sensors 33u, 33v, and 33w can detect the current values ​​of the currents Iu, Iv, and Iw flowing through the power lines 35u, 35v, and 35w, including the DC and AC components. The current sensors 33u, 33v, and 33w are, for example, DCCTs (direct current transformers) or shunt resistors.

[0039] The winding switching device 100 is positioned between the motor 20 and the power converter 30. However, the position of the winding switching device 100 is not limited to between the motor 20 and the power converter 30. The power converter 30 and the winding switching device 100 are connected by power lines 35u, 35v, and 35w, and the winding switching device 100 and the motor 20 are connected by multiple power lines 25. The winding switching device 100 switches the connection state of the multiple windings of the motor 20. The configuration of the winding switching device 100 will be described later. The three-phase AC currents Iu, Iv, and Iw output from the power converter 30 are supplied to the motor 20 via the winding switching device 100.

[0040] The control device 50 controls the motor 20. Specifically, the control device 50 controls the motor 20 by controlling the power converter 30 and the winding switching device 100. Signal lines extend from the control device 50 to switches 31u, 32u, 31v, 32v, 31w, and 32w, and the control device 50 controls the on / off timing of switches 31u, 32u, 31v, 32v, 31w, and 32w. Signal lines extend from the control device 50 to the winding switching device 100, and the control device 50 outputs a switching command signal to the winding switching device 100 to command the switching of the winding connection state.

[0041] The control device 50 is connected to a sensor 71 that detects the amount of depression of the brake pedal 70, and receives a detection signal output from the sensor 71. The control device 50 is also connected to a sensor 81 that detects the amount of depression of the accelerator pedal 80, and receives a detection signal output from the sensor 81.

[0042] A rotation sensor 201 for detecting the rotational speed of the motor 20 and a torque sensor 202 for detecting the output torque of the motor 20 are attached to the output shaft of the motor 20. The rotation sensor 201 and the torque sensor 202 are connected to a control device 50. The control device 50 receives a detection signal output from the rotation sensor 201 and a detection signal output from the torque sensor 202.

[0043] The control device 50 is connected to the gear shift indicator 90. The gear shift indicator 90 is an input device for the driver to input a gear shift command. The gear shift indicator 90 is, for example, a shift lever. In another example, the gear shift indicator 90 is a switch for the driver to signal an upshift or downshift. The gear shift indicator 90 outputs a gear shift command signal in response to the driver's operation. The control device 50 receives the gear shift command signal output from the gear shift indicator 90.

[0044] Figure 2 is a block diagram showing an example of the hardware configuration of a control device. The control device 50 includes a processor 501, a non-volatile memory 502, a volatile memory 503, and an interface (I / F) 504.

[0045] The volatile memory 503 is a semiconductor memory such as SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory). The non-volatile memory 502 is a flash memory, hard disk, ROM (Read Only Memory), etc. The non-volatile memory 502 stores the motor control program 510, which is a computer program, and the data used to execute the motor control program 510. Each function of the control device 50 is performed when the motor control program 510 is executed by the processor 501. The motor control program 510 can be stored in a recording medium such as flash memory, ROM, or CD-ROM. The processor 501 controls the power converter 30 and the winding switching device 100 using the motor control program 510.

[0046] The processor 501 is, for example, a CPU (Central Processing Unit). However, the processor 501 is not limited to a CPU. The processor 501 may also be a GPU (Graphics Processing Unit). The processor 501 may be, for example, a multi-core processor. The processor 501 may also be a single-core processor. The processor 501 may be, for example, an ASIC (Application Specific Integrated Circuit), or a programmable logic device such as a gate array or FPGA (Field Programmable Gate Array). In this case, the ASIC or programmable logic device is configured to execute the same processing as the motor control program 510.

[0047] I / F504 is connected to the rotation sensor 201, torque sensor 202, sensor 71, sensor 81, and gear shift indicator 90. I / F504 is, for example, an input / output interface or a communication interface. I / F504 receives the rotation speed detection signal of motor 20 output from rotation sensor 201. I / F504 receives the output torque detection signal of motor 20 output from torque sensor 202. I / F504 receives the brake pedal depression detection signal output from sensor 71. I / F504 receives the accelerator pedal depression detection signal output from sensor 81. I / F504 receives the gear shift instruction signal output from gear shift indicator 90.

[0048] [1-2. Configuration of the winding switching device] Figure 3 is a circuit diagram showing an example of the configuration of a winding switching device according to the first embodiment. The motor 20 includes a plurality of windings 21u, 22u, 21v, 22v, 21w, and 22w. Windings 21u and 22u correspond to the U phase, windings 21v and 22v correspond to the V phase, and windings 21w and 22w correspond to the W phase. However, the number of windings for each phase is not limited to two, but may be three or more. Windings 22u, 22v, and 22w are connected at the neutral point 23.

[0049] The winding switching device 100 switches the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w between a series connection state and a parallel connection state for each phase. The winding switching device 100 includes control circuits 103u, 103v, and 103w, and switching circuits 104u, 104v, and 104w.

[0050] The switching circuits 104u, 104v, and 104w switch the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w between a series connection state and a parallel connection state, according to control from the control device 50. The series connection state is an example of the first connection state, and the parallel connection state is an example of the second connection state.

[0051] The following explanation will describe the connection relationship between the winding switching device 100, the power line 35u, and the motor 20, using the U phase as a representative example. The V and W phases are similar, so their explanations will be omitted.

[0052] Power line 35u is connected to one end of winding 21u. Power line 212u extends from the other end of winding 21u. Power line 221u extends from one end of winding 22u, and power line 222u extends from the other end.

[0053] The switching circuit 104u includes semiconductor relays 111u, 112u, and 113u. The semiconductor relays 111u, 112u, and 113u are, for example, IGBTs or power MOSFETs.

[0054] The power line 35u is drawn into the winding switch 100. Inside the winding switch 100, the power line 35u branches at an intermediate point and is connected to the first terminal of semiconductor relay 111u. The second terminal of semiconductor relay 111u is connected to the first terminal of semiconductor relay 112u. The power line 221u, which extends from winding 22u, is connected to the connection point between the second terminal of semiconductor relay 111u and the first terminal of semiconductor relay 112u. Power lines 212u, 221u, and 222u extend from the motor 20 and are drawn into the winding switch 100.

[0055] The second terminal of semiconductor relay 112u is connected to the first terminal of semiconductor relay 113u. A power line 212u extending from winding 21u is connected to the connection point between the second terminal of semiconductor relay 112u and the first terminal of semiconductor relay 113u. The second terminal of semiconductor relay 113u is connected to a power line 222u extending from winding 22u.

[0056] When semiconductor relays 111u and 113u are in the off state and semiconductor relay 112u is in the on state, windings 21u and 22u are connected in series. When semiconductor relays 111u and 113u are in the on state and semiconductor relay 112u is in the off state, windings 21u and 22u are connected in parallel.

[0057] Signal lines extending from the control circuit 103u are connected to the gate terminals of each of the semiconductor relays 111u, 112u, and 113u. Signal lines extending from the control device 50 are connected to the control circuit 103u.

[0058] The control circuit 103u controls the on / off state of semiconductor relays 111u, 112u, and 113u by individually applying gate voltages to their gate terminals. Specifically, when the control circuit 103u receives an instruction from the control device 50 to switch the connection state of windings 21u and 22u from a series connection state to a parallel connection state, it sets semiconductor relays 111u and 113u to the ON state and sets semiconductor relay 112u to the OFF state. When the control circuit 103u receives an instruction from the control device 50 to switch the connection state of windings 21u and 22u from a parallel connection state to a series connection state, it sets semiconductor relays 111u and 113u to the OFF state and sets semiconductor relay 112u to the ON state.

[0059] The control circuit 103u is composed of, for example, multiple logic circuits (AND gates, NOT gates, latch gates, etc.). In other examples, the control circuit 103u is composed of a processor. For example, the control circuit 103u is composed of a single-chip microcomputer. The control circuit 103u may also be composed of a programmable logic device such as an ASIC or FPGA.

[0060] [1-3. Functions of the control device] Returning to Figure 1, the functions of the control device 50 will be explained. The control device 50 has the functions of a torque control unit 511 and a switching control unit 512. The functions of the torque control unit 511 and the switching control unit 512 are realized when the processor 501 executes the motor control program 510.

[0061] The torque control unit 511 changes the output torque of the motor 20 by changing the alternating current output from the power converter 30 at a predetermined shift timing of the electric vehicle. After the alternating current output from the power converter 30 has changed, the switching control unit 512 causes the winding switching device 100 to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w.

[0062] The gear shift timing is, for example, the timing at which the control device 50 receives a gear shift instruction output from the gear shift indicator 90. In other words, in a vehicle equipped with a gear shift indicator 90, when the driver instructs a gear shift using the gear shift indicator 90, the control device 50 changes the AC current output from the power converter 30 from the timing at which the gear shift instruction is input to the control device 50.

[0063] In another example, the shift timing is determined based on the rotational speed of the motor 20, the output torque of the motor 20, the amount the brake pedal 70 is pressed (braking instruction), and the amount the accelerator pedal 80 is pressed (acceleration instruction). That is, an automatic transmission control device (not shown) in the vehicle generates a shift instruction based on the rotational speed of the motor 20, the output torque of the motor 20, the amount the brake pedal 70 is pressed (braking instruction), and the amount the accelerator pedal 80 is pressed (acceleration instruction), and the generated shift instruction is input to the control device 50. When the shift instruction generated by such an automatic transmission control device is input to the control device 50, the control device 50 changes the AC current output from the power converter 30 from the moment the shift instruction is input to the control device 50.

[0064] When the windings 21u, 22u, 21v, 22v, 21w, and 22w of motor 20 are connected in series, motor 20 can output high torque. When the windings 21u, 22u, 21v, 22v, 21w, and 22w of motor 20 are connected in parallel, the output torque of motor 20 decreases at the same rotational speed compared to the series connection state. In other words, the series connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w results in a low rotational speed, high torque state for motor 20, while the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w results in a high rotational speed, low torque state for motor 20. Switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, 22w from a series connection to a parallel connection is equivalent to shifting up in a mechanical transmission, and switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, 22w from a parallel connection to a series connection is equivalent to shifting down in a mechanical transmission. Switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, 22w from a series connection to a parallel connection is also called "electrical shift up," and switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, 22w from a parallel connection to a series connection is also called "electrical shift down."

[0065] For example, the torque control unit 511 reduces the output torque of the motor 20 by reducing the AC current output from the power converter 30 at the first gear shift timing. After the AC current output from the power converter 30 decreases to a first target value or less, the switching control unit 512 instructs the winding switching device 100 to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state. The first gear shift timing is the timing at which an electrical shift up is instructed.

[0066] Figure 4 is a timing chart showing an example of the switching timing of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w in the winding switching system according to the first embodiment. Figure 4 shows an example of the timing of the speed change instruction, the current supplied to the motor 20 (hereinafter also referred to as "motor current"), the output torque of the motor 20 (hereinafter also referred to as "motor torque"), and the on / off switching of the semiconductor relays 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, and 113w when switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state. In the following, semiconductor relays 111u, 111v, and 111w will be collectively referred to as "relay 111," semiconductor relays 112u, 112v, and 112w will be collectively referred to as "relay 112," and semiconductor relays 113u, 113v, and 113w will be collectively referred to as "relay 113."

[0067] At time t11, a gear shift instruction (electrical downshift instruction) is input to the control device 50. The torque control unit 511 reduces the motor current Iq from time t11. The motor current Iq is the effective current (Q-axis current) of the AC current supplied to the motor 20. In the example shown in Figure 4, the motor current Iq gradually decreases in a ramp-like manner. As the motor current Iq decreases, the motor torque also decreases.

[0068] At time t12, the motor current Iq reaches the first target value Th1. The torque control unit 511 stops the decrease of the motor current Iq from time t12, when the motor current Iq reaches the first target value Th1. That is, from time t12 onward, the motor current Iq is maintained at the first target value Th1. From time t12 onward, the decrease in motor torque also stops.

[0069] The switching control unit 512 switches the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state at a timing after time t12. In the example in Figure 4, at time t01, which is after time t12, relays 111 and 113 are switched from the ON state to the OFF state, and at time t02, which is after time t01, relay 112 is switched from the OFF state to the ON state. During the period between time t01 and time t02, all relays 111, 112, and 113 are in the OFF state. This prevents all relays 111, 112, and 113 from being in the ON state when switching the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w.

[0070] From time t21, after time t02, the torque control unit 511 increases the motor current Iq. The target value of the motor current Iq at this time is determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w. The target torque is determined based on the rotational speed of the motor 20, the output torque of the motor 20, the amount of depression of the brake pedal 70 (braking instruction), and the amount of depression of the accelerator pedal 80 (acceleration instruction). In the example shown in Figure 4, the motor current Iq increases in a ramp-like manner. As the motor current Iq increases, the motor torque also increases.

[0071] At time t22, the motor current Iq reaches the target value. The torque control unit 511 stops increasing the motor current Iq from time t22, when the motor current Iq reaches the target value. After time t22, the motor torque also stops increasing.

[0072] As described above, by switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state, the motor 20's performance can be efficiently utilized to electrically shift from a low-speed, high-torque state to a high-speed, low-torque state. Furthermore, as the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w is switched, the output torque of the motor 20 decreases, giving the driver a shifting sensation similar to that of a mechanical transmission.

[0073] The first target value Th1 is, for example, 0A. If the connection state is switched while current is flowing through windings 21u, 22u, 21v, 22v, 21w, and 22w, a torque shock will occur due to the sudden change in current in the inductive load windings 21u, 22u, 21v, 22v, 21w, and 22w. Furthermore, damage to relays 111, 112, and 113 due to surges will also occur. By setting the first target value Th1 to 0A, the above-mentioned torque shock and damage to relays 111, 112, and 113 due to surges can be suppressed.

[0074] For example, when the rotational speed of the motor 20 is increasing, that is, when an electrical downshift is instructed while the vehicle is accelerating, the torque control unit 511 reduces the output torque of the motor 20 by reducing the alternating current output from the power converter 30 at the second gear shift timing. After the alternating current output from the power converter 30 decreases to or below the first target value, the switching control unit 512 instructs the winding switching device 100 to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a parallel connection state to a series connection state. The second gear shift timing is the timing when an electrical downshift is instructed.

[0075] By switching the connection state of the motor 20's windings 21u, 22u, 21v, 22v, 21w, and 22w from parallel to series, the motor 20's performance can be efficiently utilized to electrically shift from a high-speed, low-torque state to a low-speed, high-torque state. Furthermore, as the connection state of the motor 20's windings 21u, 22u, 21v, 22v, 21w, and 22w is switched, the output torque of the motor 20 increases, providing the driver with a shifting sensation similar to that of a mechanical transmission.

[0076] For example, when an electrical downshift is instructed while the motor 20 is performing regenerative braking, the torque control unit 511 increases the output torque of the motor 20 by increasing the alternating current output from the power converter 30 at the second shift timing. During regenerative braking, a torque is generated to brake the vehicle, i.e., a negative torque is produced, and as the output torque of the motor 20 increases (approaches 0), the braking force decreases. After the alternating current output from the power converter 30 increases to a second target value or higher, the switching control unit 512 instructs the winding switching device 100 to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a parallel connection state to a series connection state.

[0077] As described above, by switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a parallel connection state to a series connection state, the performance of the motor 20 can be efficiently utilized to electrically shift from a high-speed, low-torque state to a low-speed, high-torque state. The amount of regeneration by the motor 20 is higher in the low-speed, high-torque state than in the high-speed, low-torque state. Therefore, by electrically downshifting, the regenerative braking force can be increased, giving the driver a deceleration sensation similar to engine braking. Furthermore, as the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w is switched, the negative output torque of the motor 20 decreases (the absolute value of the output torque increases), giving the driver a shifting sensation similar to that of a mechanical transmission.

[0078] The torque control unit 511 can gradually increase the motor current Iq in a ramp-like manner during an electrical downshift. By gradually decreasing the motor current Iq in a ramp-like manner during an electrical upshift and gradually increasing it in a ramp-like manner during an electrical downshift, a natural shifting sensation can be given to the driver.

[0079] The second target value Th2 is, for example, 0A. This suppresses torque shock and surge damage to relays 111, 112, and 113 caused by sudden current changes in windings 21u, 22u, 21v, 22v, 21w, and 22w.

[0080] For example, when motor 20 is performing regenerative braking and an electrical shift-up is instructed, the torque control unit 511 increases the output torque of motor 20 by increasing the AC current output from power converter 30 at the first shift timing. After the AC current output from power converter 30 increases to a second target value or higher, the switching control unit 512 instructs the winding switching device 100 to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state.

[0081] By switching the connection state of the motor 20's windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection to a parallel connection, the motor 20's performance can be efficiently utilized to electrically shift from a low-speed, high-torque state to a high-speed, low-torque state. Electrical shifting reduces regenerative braking force, giving the driver a deceleration sensation similar to engine braking. Furthermore, as the connection state of the motor 20's windings 21u, 22u, 21v, 22v, 21w, and 22w is switched, the negative output torque of the motor 20 increases (the absolute value of the output torque decreases), giving the driver a shifting sensation similar to that of a mechanical transmission.

[0082] [1-4. Operation of the winding switching system] Next, the operation of the winding switching device 100 will be described. The control device 50 performs electrical shift-up processing and electrical shift-down processing by having the processor 501 execute the motor control program 510.

[0083] Figure 5 is a flowchart showing an example of an electrical shift-up process by the control device according to the first embodiment. In this example, it is assumed that at the start of the electrical shift-up process, the windings 21u, 22u, 21v, 22v, 21w, and 22w of the motor 20 are connected in series.

[0084] When the driver wants to perform an electric upshift, they operate the gear shift indicator 90 to input an electric upshift command to the vehicle. The processor 501 accepts the electric upshift command (step S101).

[0085] The processor 501 refers to the detection signal from the torque sensor 202 and determines whether the motor torque is positive, that is, whether the motor 20 is generating torque (hereinafter referred to as "acceleration torque") necessary for the vehicle to accelerate or maintain speed (step S102).

[0086] If the motor torque is positive (YES in step S102), the processor 501 outputs an instruction to the power converter 30 to reduce the motor current Iq (step S103). This initiates the reduction of the motor current Iq.

[0087] The processor 501 obtains the current value of the motor current Iq from the detection signals of the current sensors 33u, 33v, and 33w, and determines whether the motor current Iq is less than or equal to the first target value Th1 (step S104).

[0088] If the motor current Iq is greater than the first target value Th1 (NO in step S104), the processor 501 repeats step S104. If the motor current Iq is less than or equal to the first target value Th1 (YES in step S104), the processor 501 outputs an instruction to the power converter 30 to stop the decrease in motor current Iq (step S105). This stops the decrease in motor current Iq.

[0089] The processor 501 outputs an instruction to the winding switching device 100 to switch the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state (step S106). As a result, while the motor current Iq is less than or equal to the first target value Th1, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a series connection state to a parallel connection state, and an electrical shift-up occurs.

[0090] The processor 501 outputs an instruction to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w, and then outputs an instruction to the power converter 30 to increase the motor current Iq (step S107). This starts the increase in motor current Iq.

[0091] When the motor current reaches a target value determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w, the processor 501 outputs an instruction to the power converter 30 to stop increasing the motor current Iq (step S108). As a result, the increase in motor current Iq stops. This completes the electrical shift-up process when the motor torque is positive.

[0092] If the motor torque is negative (NO in step S102), the motor 20 is performing regenerative braking. The power converter 30 functions as a DC / AC converter and converts the alternating current output from the motor 20 into a direct current. The converted direct current is output to the battery 40 and stored. In this case, the processor 501 outputs an instruction to the power converter 30 to increase the motor current Iq (step S109). This initiates the increase in the motor current Iq.

[0093] The processor 501 obtains the current value of the motor current Iq from the detection signals of the current sensors 33u, 33v, and 33w, and determines whether the motor current Iq is greater than or equal to the second target value Th2 (step S110).

[0094] If the motor current Iq is less than the second target value Th2 (NO in step S110), the processor 501 executes step S110 again. If the motor current Iq is greater than or equal to the second target value Th2 (YES in step S110), the processor 501 outputs an instruction to the power converter 30 to stop increasing the motor current Iq (step S111). As a result, the increase in the motor current Iq stops.

[0095] The processor 501 outputs an instruction to the winding switching device 100 to switch the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state (step S112). As a result, while the motor current Iq is greater than or equal to the second target value Th2, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a series connection state to a parallel connection state, and an electrical shift-up occurs.

[0096] The processor 501 outputs an instruction to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w, and then outputs an instruction to the power converter 30 to reduce the motor current Iq (step S112). This initiates the reduction of the motor current Iq.

[0097] When the motor current reaches a target value determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w, the processor 501 outputs an instruction to the power converter 30 to stop the decrease of the motor current Iq (step S113). As a result, the decrease of the motor current Iq stops. This completes the electrical shift-up process in the case of negative motor torque.

[0098] Figure 6 is a flowchart showing an example of electrical shift-down processing by the control device according to the first embodiment. In this example, it is assumed that the windings 21u, 22u, 21v, 22v, 21w, and 22w of the motor 20 are connected in parallel at the start of the electrical shift-down processing.

[0099] When the driver wants to perform an electric downshift, they operate the gear shift indicator 90 to input an electric downshift instruction to the vehicle. The processor 501 accepts the electric downshift instruction (step S201).

[0100] The processor 501 refers to the detection signal from the torque sensor 202 and determines whether the motor torque is positive, that is, whether the motor 20 is generating acceleration torque (step S202).

[0101] If the motor torque is positive (YES in step S202), the processor 501 outputs an instruction to the power converter 30 to reduce the motor current Iq (step S203). This initiates the reduction of the motor current Iq.

[0102] The processor 501 obtains the current value of the motor current Iq from the detection signals of the current sensors 33u, 33v, and 33w, and determines whether the motor current Iq is less than or equal to the first target value Th1 (step S204).

[0103] If the motor current Iq is greater than the first target value Th1 (NO in step S204), the processor 501 executes step S204 again. If the motor current Iq is less than or equal to the first target value Th1 (YES in step S204), the processor 501 outputs an instruction to the power converter 30 to stop the decrease in motor current Iq (step S205). As a result, the decrease in motor current Iq stops.

[0104] The processor 501 outputs an instruction to the winding switching device 100 to switch the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w from a parallel connection state to a series connection state (step S206). As a result, while the motor current Iq is less than or equal to the first target value Th1, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a parallel connection state to a series connection state, and an electrical downshift occurs.

[0105] The processor 501 outputs an instruction to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w, and then outputs an instruction to the power converter 30 to increase the motor current Iq (step S207). This starts the increase in motor current Iq.

[0106] When the motor current reaches a target value determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w, the processor 501 outputs an instruction to the power converter 30 to stop increasing the motor current Iq (step S208). As a result, the increase in motor current Iq stops. This completes the electrical shift-down process when the motor torque is positive.

[0107] If the motor torque is negative (NO in step S202), the motor 20 is performing regenerative braking. In this case, the processor 501 outputs an instruction to the power converter 30 to increase the motor current Iq (step S209). This initiates the increase in the motor current Iq.

[0108] The processor 501 obtains the current value of the motor current Iq from the detection signals of the current sensors 33u, 33v, and 33w, and determines whether the motor current Iq is greater than or equal to the second target value Th2 (step S210).

[0109] If the motor current Iq is less than the second target value Th2 (NO in step S210), the processor 501 executes step S210 again. If the motor current Iq is greater than or equal to the second target value Th2 (YES in step S210), the processor 501 outputs an instruction to the power converter 30 to stop increasing the motor current Iq (step S211). As a result, the increase in the motor current Iq stops.

[0110] The processor 501 outputs an instruction to the winding switching device 100 to switch the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w from a parallel connection state to a series connection state (step S212). As a result, while the motor current Iq is greater than or equal to the second target value Th2, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a parallel connection state to a series connection state, and an electrical downshift occurs.

[0111] The processor 501 outputs an instruction to switch the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w, and then outputs an instruction to the power converter 30 to reduce the motor current Iq (step S212). This initiates the reduction of the motor current Iq.

[0112] When the motor current reaches a target value determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w, the processor 501 outputs an instruction to the power converter 30 to stop the decrease of the motor current Iq (step S213). As a result, the decrease of the motor current Iq stops. This completes the electrical shift-down process in the case of negative motor torque.

[0113] [2. Second Embodiment] The winding switching device according to the second embodiment switches the connection state of the motor's multiple windings between a fully connected state in which all of the multiple windings are connected and a partially connected state in which some of the multiple windings are connected.

[0114] Figure 7 is a circuit diagram showing an example of the configuration of a winding switching device according to the second embodiment. The motor 20A includes a plurality of windings 24u, 25u, 24v, 25v, 24w, and 25w. Windings 24u and 25u correspond to the U phase, windings 24v and 25v correspond to the V phase, and windings 24w and 25w correspond to the W phase. However, the number of windings for each phase is not limited to two, and may be three or more.

[0115] The winding switching device 100A switches the connection state of windings 24u, 25u, 24v, 25v, 24w, and 25w for each phase between a fully connected state and a partially connected state. The winding switching device 100A includes control circuits 103u, 103v, and 103w, and switching circuits 140u, 140v, and 140w.

[0116] The switching circuit 140u, 140v, 140w switches the connection state of windings 24u, 25u, 24v, 25v, 24w, and 25w between a fully connected state and a partially connected state. The fully connected state is an example of the first connection state, and the partially connected state is an example of the second connection state.

[0117] Power line 35u is connected to one end of winding 24u. The other end of winding 24u and one end of winding 25u are connected to each other, and power line 241u extends from the midpoint between windings 24u and 25u. Power line 241u branches into power lines 242u and 243w. Power line 251u extends from the other end of winding 25u. Power line 251u branches into power lines 252u and 253w.

[0118] Power line 35V is connected to one end of winding 24V. The other end of winding 24V and one end of winding 25V are connected to each other, and power line 241V extends from the midpoint between windings 24V and 25V. Power line 241V branches into power lines 242V and 243u. Power line 251V extends from the other end of winding 25V. Power line 251V branches into power lines 252V and 253u.

[0119] Power line 35W is connected to one end of winding 24W. The other end of winding 24W and one end of winding 25W are connected to each other, and power line 241W extends from the midpoint between windings 24W and 25W. Power line 241W branches into power lines 242W and 243V. Power line 251W extends from the other end of winding 25W. Power line 251W branches into power lines 252W and 253V.

[0120] Switching circuit 140u includes semiconductor relays 141u and 142u. Switching circuit 140v includes semiconductor relays 141v and 142v. Switching circuit 140w includes semiconductor relays 141w and 142w. The semiconductor relays 141u, 142u, 141v, 142v, 141w, and 142w are, for example, IGBTs or power MOSFETs.

[0121] In switching circuit 140u, the first terminal of semiconductor relay 141u is connected to power line 242u, and its second terminal is connected to power line 243u. The first terminal of semiconductor relay 142u is connected to power line 252u, and its second terminal is connected to power line 253u. The connection relationships of switching circuits 140v and 140w are the same as those of switching circuit 140u, so the explanation is omitted.

[0122] When semiconductor relays 141u, 141v, and 141w are in the off state and semiconductor relays 142u, 142v, and 142w are in the on state, all windings 24u, 25u, 24v, 25v, 24w, and 25w are connected, resulting in a fully connected state. When semiconductor relays 141u, 141v, and 141w are in the on state and semiconductor relays 142u, 142v, and 142w are in the off state, only windings 24u, 24v, and 24w are connected, resulting in a partially connected state.

[0123] The other configurations of the winding switching device 100A according to the second embodiment are the same as those of the winding switching device 100 according to the first embodiment; therefore, the same reference numerals are used for the same components, and their descriptions are omitted.

[0124] In the second embodiment, an electrical shift-up occurs when the connection state of the motor 20 windings 24u, 25u, 24v, 25v, 24w, and 25w switches from a fully connected state to a partially connected state. An electrical shift-down occurs when the connection state of the motor 20 windings 24u, 25u, 24v, 25v, 24w, and 25w switches from a partially connected state to a fully connected state.

[0125] [3. Third Embodiment] In the third embodiment, the torque control unit 511 changes the effective current of the AC current output from the power converter 30 in a step-like manner based on the gear shift timing.

[0126] Figure 8 is a timing chart showing an example of the switching timing of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w in the winding switching system according to the third embodiment. Since the configuration of the winding switching system according to the third embodiment is the same as the configuration of the winding switching system 10 according to the first embodiment, the same reference numerals are used for the same components and their descriptions are omitted.

[0127] Figure 8 shows an example of the timing of the speed change instruction, motor current, motor torque, and the on / off switching of semiconductor relays 111, 112, and 113 when switching the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state.

[0128] At time t1, a gear shift instruction (electrical shift-up instruction) is input to the control device 50. At time t1, the torque control unit 511 reduces the motor current Iq in a stepwise manner to a value less than or equal to the first target value Th1. As the motor current Iq decreases, the motor torque also decreases in a stepwise manner. After time t1, the motor current Iq is maintained at the first target value Th1.

[0129] The switching control unit 512 switches the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state at a timing after time t1. In the example in Figure 8, at time t01, which is after time t1, relays 111 and 113 are switched from the ON state to the OFF state, and at time t02, which is after time t01, relay 112 is switched from the OFF state to the ON state. During the period between time t01 and time t02, all relays 111, 112, and 113 are in the OFF state. This prevents all relays 111, 112, and 113 from being in the ON state when switching the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w.

[0130] At time t2, which is after time t02, the torque control unit 511 increases the motor current Iq in a stepwise manner. The target value of the motor current Iq at this time is determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w. The target torque is determined based on the rotational speed of the motor 20, the output torque of the motor 20, the amount of depression of the brake pedal 70 (braking instruction), and the amount of depression of the accelerator pedal 80 (acceleration instruction). As the motor current Iq increases, the motor torque also increases in a stepwise manner.

[0131] As the connection state of the motor 20's windings 21u, 22u, 21v, 22v, 21w, and 22w is switched, the output torque of the motor 20 decreases in a step-like manner, providing the driver with a shifting sensation similar to that of a mechanical transmission.

[0132] [4. Fourth Embodiment] In the fourth embodiment, the torque control unit 511 changes the effective current of the AC current output from the power converter 30 in a curved manner based on the gear shift timing.

[0133] Figure 9 is a timing chart showing an example of the switching timing of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w in the winding switching system according to the fourth embodiment. Figure 9 shows an example of the timing of the speed change instruction, motor current, motor torque, and the on / off switching of semiconductor relays 111, 112, and 113 when switching the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state.

[0134] At time t11, a gear shift instruction (electrical shift-up instruction) is input to the control device 50. The torque control unit 511 reduces the motor current Iq in a curve from time t11. In the example shown in Figure 9, the slope of the decrease in motor current Iq gradually increases from time t11, and the slope becomes infinite at the midpoint between time t11 and time t12. After that, the slope of the decrease in motor current Iq gradually decreases, and the slope becomes 0 (decrease stops) at time t12.

[0135] At time t12, the motor current Iq reaches the first target value Th1. The torque control unit 511 stops the decrease of the motor current Iq from time t12, when the motor current Iq reaches the first target value Th1. That is, from time t12 onward, the motor current Iq is maintained at the first target value Th1. From time t12 onward, the decrease in motor torque also stops.

[0136] The switching control unit 512 switches the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state at a timing after time t12. In the example in Figure 9, at time t01, which is after time t12, relays 111 and 113 are switched from the ON state to the OFF state, and at time t02, which is after time t01, relay 112 is switched from the OFF state to the ON state. During the period between time t01 and time t02, all relays 111, 112, and 113 are in the OFF state. This prevents all relays 111, 112, and 113 from being in the ON state when switching the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w.

[0137] From time t21, after time t02, the torque control unit 511 increases the motor current Iq. The target value of the motor current Iq at this time is determined based on the target torque in the parallel connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w. The target torque is determined based on the rotational speed of the motor 20, the output torque of the motor 20, the amount of depression of the brake pedal 70 (braking instruction), and the amount of depression of the accelerator pedal 80 (acceleration instruction). In the example shown in Figure 9, the motor current Iq increases curvilinearly. As the motor current Iq increases, the motor torque also increases.

[0138] In the example shown in Figure 9, the slope of increase in the motor current Iq gradually increases from time t21, and the slope becomes infinite at the midpoint between time t21 and time t22. After that, the slope of increase in the motor current Iq gradually decreases, and the slope becomes 0 (increase stops) at time t22.

[0139] At time t22, the motor current Iq reaches the target value. The torque control unit 511 stops increasing the motor current Iq from time t22, when the motor current Iq reaches the target value. After time t22, the motor torque also stops increasing.

[0140] As the connection state of the motor 20's windings 21u, 22u, 21v, 22v, 21w, and 22w is switched, the output torque of the motor 20 decreases in a curved manner. In the fourth embodiment, sharp changes in motor torque are suppressed, so the driver can be given a shifting sensation similar to that of a mechanical transmission.

[0141] [5. Fifth Embodiment] In the fifth embodiment, the torque control unit 511 performs a pseudo-shift control process in which it decreases and then increases the AC current output from the power converter 30 at a pseudo-shift timing that is different from the timing of the electrical shift up and electrical shift down (electric shift timing).

[0142] Figure 10 is a timing chart showing an example of pseudo-speed change control processing in a winding switching system according to the fifth embodiment. Figure 10 shows an example of the timing of the speed change instruction, motor current, motor torque, and on / off switching of semiconductor relays 111, 112, 113 when switching the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, 22w from a series connection state to a parallel connection state.

[0143] At time t31, a gear shift instruction (pseudo-gear shift instruction) is input to the control device 50. The torque control unit 511 reduces the motor current Iq from time t31. In the example shown in Figure 10, the motor current Iq gradually decreases in a ramp-like manner. As the motor current Iq decreases, the motor torque also decreases.

[0144] At time t32, the motor current Iq is 1 The target value Th1 is reached. The torque control unit 511 stops the decrease of the motor current Iq from time t32, when the motor current Iq reaches the first target value Th1. That is, from time t32 onward, the motor current Iq is maintained at the first target value Th1. From time t32 onward, the decrease in motor torque also stops.

[0145] The torque control unit 511 maintains the motor current Iq at a first target value Th1 for a certain period of time. During this period, the switching control unit 512 does not switch the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w. That is, semiconductor relays 111 and 113 remain in the ON state, and semiconductor relay 112 remains in the OFF state.

[0146] From time t41, after time t32, the torque control unit 511 increases the motor current Iq. That is, the torque control unit 511 maintains the motor current Iq at the first target value Th1 for a certain period of time, and then increases it. Alternatively, the torque control unit 511 may increase the motor current Iq without a stop period after the motor current Iq has decreased to or below the first target value Th1.

[0147] The target value of the motor current Iq at this time is set to be the same as the target value before the change in motor current Iq. In the example shown in Figure 10, the motor current Iq increases in a ramp-like manner. As the motor current Iq increases, the motor torque also increases.

[0148] At time t42, the motor current Iq reaches the target value. The torque control unit 511 stops increasing the motor current Iq from time t42, when the motor current Iq reaches the target value. After time t42, the motor torque also stops increasing.

[0149] Figure 11 is a flowchart showing an example of simulated gear shifting processing by the control device according to the fifth embodiment.

[0150] The driver operates the gear shift indicator 90 to input a gear shift command to the vehicle. The processor 501 accepts the gear shift command (step S301).

[0151] The processor 501 refers to the detection signal from the torque sensor 202 and determines whether the motor torque is positive, that is, whether the motor 20 is generating acceleration torque (step S302).

[0152] If the motor torque is positive (YES in step S302), the processor 501 outputs an instruction to the power converter 30 to reduce the motor current Iq (step S303). This initiates the reduction of the motor current Iq.

[0153] The processor 501 obtains the current value of the motor current Iq from the detection signals of the current sensors 33u, 33v, and 33w, and determines whether the motor current Iq is less than or equal to the first target value Th1 (step S304).

[0154] If the motor current Iq is greater than the first target value Th1 (NO in step S304), the processor 501 repeats step S304. If the motor current Iq is less than or equal to the first target value Th1 (YES in step S304), the processor 501 outputs an instruction to the power converter 30 to stop the decrease in motor current Iq (step S305). This stops the decrease in motor current Iq.

[0155] The processor 501 outputs an instruction to the power converter 30 to increase the motor current Iq without switching the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w (step S306). This initiates the increase in the motor current Iq.

[0156] When the motor current Iq reaches the same target value as before the change in motor current Iq, the processor 501 outputs an instruction to the power converter 30 to stop the increase in motor current Iq (step S307). As a result, the increase in motor current Iq stops. This completes the pseudo-speed change process when the motor torque is positive.

[0157] If the motor torque is negative (NO in step S302), the motor 20 is performing regenerative braking. In this case, the processor 501 outputs an instruction to the power converter 30 to increase the motor current Iq (step S308). This initiates the increase in the motor current Iq.

[0158] The processor 501 obtains the current value of the motor current Iq from the detection signals of the current sensors 33u, 33v, and 33w, and determines whether the motor current Iq is greater than or equal to the second target value Th2 (step S309).

[0159] If the motor current Iq is less than the second target value Th2 (NO in step S309), the processor 501 executes step S309 again. If the motor current Iq is greater than or equal to the second target value Th2 (YES in step S309), the processor 501 outputs an instruction to the power converter 30 to stop increasing the motor current Iq (step S310). As a result, the increase in the motor current Iq stops.

[0160] The processor 501 outputs an instruction to the power converter 30 to reduce the motor current Iq without switching the connection state of the motor windings 21u, 22u, 21v, 22v, 21w, and 22w (step S311). This initiates the reduction of the motor current Iq.

[0161] When the motor current Iq reaches the same target value as before the change in motor current Iq, the processor 501 outputs an instruction to the power converter 30 to stop the decrease in motor current Iq (step S312). As a result, the decrease in motor current Iq stops. This completes the pseudo-speed change process when the motor torque is negative.

[0162] As described above, since the output torque of the motor 20 changes in response to a speed change instruction without switching the connection state of the motor 20 windings 21u, 22u, 21v, 22v, 21w, and 22w, it is possible to give the driver a pseudo-speed change sensation even when no electrical speed change is performed.

[0163] By combining the simulated gear shifting process described above with electrical gear shifting, it is possible to simulate the feeling of multi-speed gear shifting to the driver. For example, by performing simulated gear shifting when switching between 1st and 2nd gear, 2nd and 3rd gear, 4th and 5th gear, and 5th and 6th gear, and performing electrical gear shifting (electric upshifting and electrical downshifting) when switching between 3rd and 4th gear, the driver can be given a simulated feeling of a 6-speed gear system, while the switch between 3rd and 4th gear utilizes the motor's performance efficiently for electrical gear shifting.

[0164] [6. Sixth Embodiment] Referring to Figure 3, the configuration of the winding switching system according to the sixth embodiment will be described.

[0165] The winding switching device 100 has voltage sensors 34u, 34v, and 34w for detecting the voltage in windings 21u, 21v, and 21w. In a specific example, voltage sensor 34u is placed between power line 35u and power line 212u, voltage sensor 34v is placed between power line 35v and power line 212v, and voltage sensor 34w is placed between power line 35w and power line 212w. Voltage sensors 34u, 34v, and 34w are connected to a control device 50. The control device 50 can receive the detected values ​​of voltage sensors 34u, 34v, and 34w.

[0166] The other components of the winding switching system according to the sixth embodiment are the same as those of the winding switching system 10 according to the first embodiment; therefore, the same reference numerals are used for the same components, and their descriptions are omitted.

[0167] Figure 12 is a functional block diagram showing an example of the functions of the control device according to the sixth embodiment. In addition to the torque control unit 511 and the switching control unit 512, the control device 50A includes the functions of a first determination unit 513, a judgment unit 514, a prohibition unit 515, and a second determination unit 516.

[0168] Since the functions of the torque control unit 511 and the switching control unit 512 are the same as in the first embodiment, a detailed explanation will be omitted.

[0169] The first determination unit 513 determines the timing before the induced voltage generated in windings 21u, 22u, 21v, 22v, 21w, and 22w exceeds the output voltage of the battery 40, when the connection state of the multiple windings 21u, 22u, 21v, 22v, 21w, and 22w is in a series connection state, as the first forced shift timing. The first forced shift timing is the timing to initiate a forced switching of the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state, regardless of whether or not there is a shift instruction from the shift indicator 90 or the automatic shift control device.

[0170] Windings 21u, 22u, 21v, 22v, 21w, and 22w generate induced voltages corresponding to the rotational speed of the motor 20. The power converter 30 can control the applied voltage to windings 21u, 22u, 21v, 22v, 21w, and 22w within the range of the output voltage of the battery 40. Since the polarity of the induced voltages in windings 21u, 22u, 21v, 22v, 21w, and 22w is the opposite of the polarity of the applied voltage, if the induced voltage exceeds the output voltage of the battery 40, winding 21 u It becomes impossible to reduce the current to zero at 22u, 21v, 22v, 21w, and 22w. Therefore, when the first target value Th1 is 0A, if the induced voltage exceeds the output voltage of the battery 40, the motor current Iq cannot be reduced to the first target value Th1 during the electrical shift-up process.

[0171] Therefore, in the sixth embodiment, the first determination unit 513 monitors the induced voltages generated in the windings 21u, 22u, 21v, 22v, 21w, and 22w in the series connection state, and determines the timing before the induced voltage transitions from a range less than or equal to the output voltage of the battery 40 to a range exceeding the output voltage as the first forced shift timing.

[0172] The torque control unit 511 changes the output torque of the motor 20 by changing the alternating current output from the power converter 30 at the first forced speed change timing determined by the first determination unit 513. After the alternating current has changed, the switching control unit 512 causes the winding switching device 100 to switch the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state.

[0173] In a specific example, once the first determination unit 513 determines the first forced gear shift timing, it generates an electrical shift-up instruction. This initiates the electrical shift-up process.

[0174] In a specific example, the first determination unit 513 can determine the timing at which a physical quantity related to the induced voltage exceeds a first threshold corresponding to the output voltage of the battery 40 as the first forced speed change timing. The physical quantity is, for example, the rotational speed of the motor 20. In this case, the first determination unit 513 can obtain a detected value from the rotation sensor 201. Another example of a physical quantity is the voltage in windings 21u, 21v, and 21w. In this case, detected values ​​can be obtained from voltage sensors 34u, 34v, and 34w, respectively. The physical quantity may also be the current flowing through windings 21u, 22u, 21v, 22v, 21w, and 22w, or the output torque of the motor 20. In the following description, the physical quantity will be the rotational speed of the motor 20.

[0175] The determination unit 514 determines whether the induced voltage after the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a parallel connection state to a series connection state exceeds the output voltage of the battery, when the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is in a parallel connection state.

[0176] In a specific example, the determination unit 514 can determine whether a physical quantity relating to the induced voltage in a series connection state is less than or equal to a second threshold corresponding to the output voltage of the battery 40. More specifically, the determination unit 514 obtains the rotational speed of the motor 20. From the rotational speed of the motor 20, the induced voltage when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series can be identified. The second threshold is, for example, the rotational speed of the motor 20 when the induced voltage when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series is equal to the output voltage of the battery 40. However, the second threshold is not limited to this. For example, the second threshold may be the rotational speed of the motor 20 when the induced voltage when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series is lower than the output voltage of the battery 40 by a predetermined margin.

[0177] The prohibition unit 515 prohibits the switching control unit 512 from switching the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w when the determination unit 514 determines that the induced voltage exceeds the output voltage of the battery 40. In a specific example, the prohibition unit 515 prohibits the switching control unit 512 from switching the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w while the rotational speed of the motor 20 exceeds the second threshold. As a result, the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a parallel connection state to a series connection state, preventing the induced voltage from exceeding the output voltage of the battery 40.

[0178] When the rotational speed of the motor 20 falls below the second threshold, the prohibition unit 515 releases the prohibition on the switching control of the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w by the switching control unit 512.

[0179] The second determination unit 516 determines the second forced shift timing to be the timing after the induced voltage of the windings 21u, 22u, 21v, 22v, 21w, 22w becomes less than or equal to the output voltage of the battery 40, when the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w is switched from a parallel connection state to a series connection state, when the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w is in a parallel connection state. The second forced shift timing is the timing to initiate a forced switch from the parallel connection state to the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w, regardless of whether or not there is a shift instruction from the shift indicator 90 or the automatic shift control device.

[0180] In a series connection, regenerative power can be recovered more efficiently than in a parallel connection. Furthermore, in a series connection, the higher the rotational speed of the motor 20, the greater the amount of regeneration. Therefore, for example, when the vehicle is decelerating in a parallel connection, in order to efficiently recover regenerative power, it is preferable to perform an electrical downshift at the timing when the rotational speed of the motor 20 is as high as possible, within the range where the induced voltage after switching to a series connection is less than or equal to the output voltage of the battery 40.

[0181] The second determination unit 516 estimates the induced voltages generated in the windings 21u, 22u, 21v, 22v, 21w, and 22w in the series connection state, and determines the timing at which the induced voltage transitions from a range exceeding the output voltage of the battery 40 to a range below the output voltage of the battery 40 as the second forced speed change timing.

[0182] The torque control unit 511 changes the output torque of the motor 20 by changing the alternating current output from the power converter 30 at the second forced speed change timing determined by the second determination unit 516. After the alternating current has changed, the switching control unit 512 causes the winding switching device 100 to switch the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w from a parallel connection state to a series connection state.

[0183] In a specific example, once the second determination unit 516 determines the second forced shift timing, it generates an electrical downshift instruction. This initiates the electrical downshift process.

[0184] In a specific example, the second determination unit 516 can determine the timing at which a physical quantity related to the induced voltage falls below a second threshold corresponding to the output voltage of the battery 40 as the second forced speed change timing. For example, the second determination unit 516 determines the timing at which the rotational speed of the motor 20 falls below a second threshold as the second forced speed change timing.

[0185] The operation of the winding switching system according to the sixth embodiment will now be described. The control device 50A performs the following forced shift-up determination process and forced shift-down determination process.

[0186] Figure 13 is a flowchart showing an example of a forced shift-up determination process by the control device according to the sixth embodiment. In this example, it is assumed that the windings 21u, 22u, 21v, 22v, 21w, and 22w of the motor 20 are connected in series.

[0187] The rotation sensor 201 detects the rotational speed of the output shaft of the motor 20 and outputs the detected rotational speed. For example, the rotation sensor 201 detects the rotational speed at a constant period and outputs the detection result. The control device 50A receives the detected value of the rotational speed output from the rotation sensor 201 (step S401).

[0188] The processor 501 compares the acquired rotational speed R with a first threshold Th1_R and determines whether the rotational speed R exceeds the first threshold Th1_R (step S402). The first threshold Th1_R is a value that is lower by a predetermined margin than the rotational speed of the motor 20 when the induced voltages generated in the windings 21u, 22u, 21v, 22v, 21w, and 22w in the series connection state match the output voltage of the battery 40.

[0189] If the rotational speed R is less than or equal to the first threshold Th1_R (NO in step S402), the processor 501 returns to step S401.

[0190] If the rotational speed R exceeds the first threshold Th1_R (YES in step S402), the processor 501 determines that timing as the first forced gear shift timing. The processor 501 generates an electrical shift-up instruction (step S403).

[0191] Next, processor 501 starts the electrical shift-up process (step S404). As a result, after the motor current Iq decreases, the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w switches from a series connection state to a parallel connection state. With this, the forced shift-up determination process is completed.

[0192] Figure 14 is a flowchart showing an example of a forced shift-down determination process by the control device according to the sixth embodiment. In this example, it is assumed that the windings 21u, 22u, 21v, 22v, 21w, and 22w of the motor 20 are connected in parallel.

[0193] The control device 50A receives the detected rotational speed output from the rotation sensor 201 (step S501).

[0194] The processor 501 compares the acquired rotational speed R with the second threshold Th2_R and determines whether the rotational speed R is less than or equal to the second threshold Th2_R (step S502). The second threshold Th2_R is a value that is lower by a predetermined margin than the rotational speed of the motor 20 when the induced voltages generated in the windings 21u, 22u, 21v, 22v, 21w, 22w in the series connection state match the output voltage of the battery 40. The second threshold Th2_R may be the same value as the first threshold Th1_R or a different value. For example, the second threshold Th2_R is lower than the first threshold Th1_R. This prevents the rotational speed R from exceeding the first threshold Th1_R soon after the electrical downshift is completed, thus preventing a forced upshift from being performed.

[0195] If the rotational speed R is greater than the second threshold Th2_R (NO in step S502), the processor 501 prohibits electrical downshifting (step S503). As a result, even if the driver gives an electrical downshifting instruction, for example, electrical downshifting will not be performed. With electrical downshifting prohibited, the processor 501 returns to step S501.

[0196] If the rotational speed R is less than or equal to the second threshold Th2_R (YES in step S502), the processor 501 determines that timing as the second forced gear shift timing. In this case, if electrical downshifting is prohibited, the processor 501 releases the prohibition on electrical downshifting. Once the processor 501 has determined the second forced gear shift timing, it generates an electrical downshift instruction (step S504).

[0197] Next, processor 501 starts the electrical downshift process (step S505). As a result, after the motor current Iq approaches zero, the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w switches from a parallel connection state to a series connection state. This completes the forced downshift determination process.

[0198] [7. Supplementary Notes] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and includes the meaning of equivalents to the claims and all modifications within that scope. [Explanation of Symbols]

[0199] 10. Winding switching system 20 Motor (Drive Motor) 21u, 22u, 21v, 22v, 21w, 22w winding 23 Neutral point 25 Power lines 30 Power Converters 31u, 32u, 31v, 32v, 31w, 32w switch 33u,33v,33w current sensor 34u, 34v, 34w voltage sensor 35u,35v,35w power line 40 batteries 50, 50A control device 501 Processor 502 Non-volatile memory 503 Volatile memory 504 Interface (I / F) 510 Motor control program 511 Torque Control Unit 512 Switching Control Unit 513 First Decision Section 514 Judgment section 515 Prohibited part 516 Second Decision Section 60 wheels 70 Brake pedal 71 CM 80 Accelerator pedal 81 Sensors 90 Gear shift indicator 100 Winding Switching Device 103u, 103v, 103w control circuit 104u, 104v, 104w switching circuit 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, 113w semiconductor relays 201 Rotation Sensor 202 Torque Sensor 212u,221u,222u power line 20A motor 24u, 25u, 24v, 25v, 24w, 25w winding 100A Winding Switching Device 140u, 140v, 140w switching circuit 141u, 142u, 141v, 142v, 141w, 142w semiconductor relays 241u, 242u, 243u, 251u, 252u, 253u, 241v, 242v, 243v, 251v, 252v, 253v, 241w, 242w, 243w, 251w, 252w, 253w Power lines

Claims

1. The drive motor that drives the vehicle's wheels, A control device for controlling the drive motor, A power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor, A winding switching device that switches the connection state of multiple windings in the drive motor between a first connection state and a second connection state in which the drive motor outputs a lower torque than the first connection state at the same rotational speed, Equipped with, The control device is A torque control unit that changes the output torque of the drive motor by changing the AC current output from the power converter at a predetermined shift timing of the vehicle, A switching control unit that causes the winding switching device to switch from the first connection state to the second connection state after the AC current has changed, A determination unit that determines whether the induced voltage generated in the winding after the connection state of the winding is switched from the second connection state to the first connection state exceeds the output voltage of the battery, when the connection state of the plurality of windings is in the second connection state, When the determination unit determines that the induced voltage exceeds the output voltage of the battery, a prohibition unit prohibits the switching control unit from switching the connection state of the winding, including, A winding switching system for vehicle motors.

2. The torque control unit reduces the output torque of the drive motor by reducing the AC current output from the power converter at the first gear shift timing. The switching control unit causes the winding switching device to switch from the first connection state to the second connection state after the AC current has decreased to or below the first target value. A winding switching system for a vehicle motor according to claim 1.

3. The torque control unit reduces the output torque of the drive motor by reducing the AC current output from the power converter at a second shift timing different from the first shift timing. The switching control unit causes the winding switching device to switch from the second connection state to the first connection state after the AC current has decreased to or below the first target value. A winding switching system for a vehicle motor according to claim 2.

4. The torque control unit increases the output torque of the drive motor by increasing the AC current output from the power converter at the first gear shift timing. The switching control unit causes the winding switching device to switch from the first connection state to the second connection state after the AC current has increased to the second target value or higher. A winding switching system for a vehicle motor according to claim 1.

5. The torque control unit increases the output torque of the drive motor by increasing the AC current output from the power converter at a second shift timing different from the first shift timing. The switching control unit causes the winding switching device to switch from the second connection state to the first connection state after the AC current has increased to the second target value or higher. A winding switching system for a vehicle motor according to claim 4.

6. The control device further includes a first determination unit that determines the timing before the induced voltage generated in the windings exceeds the output voltage of the battery when the connection state of the plurality of windings is in a first connection state as a first forced shift timing, The torque control unit changes the output torque of the drive motor by changing the AC current output from the power converter at the first forced shift timing determined by the first determination unit. The switching control unit causes the winding switching device to switch from the first connection state to the second connection state after the AC current has changed. A winding switching system for a vehicle motor according to claim 1.

7. The first determination unit determines the timing at which the physical quantity related to the induced voltage exceeds a first threshold corresponding to the output voltage of the battery as the first forced shift timing. A winding switching system for a vehicle motor according to claim 6.

8. The aforementioned physical quantity is one of the following: the voltage in the winding, the rotational speed of the drive motor, the current flowing through the winding, and the output torque of the drive motor. A winding switching system for a vehicle motor according to claim 7.

9. The control device further includes a second determination unit that determines the timing after the induced voltage becomes less than or equal to the output voltage of the battery when the connection state of the plurality of windings is switched from the second connection state to the first connection state, when the connection state of the windings is in the second connection state, as the second forced shift timing. The torque control unit changes the output torque of the drive motor by changing the AC current output from the power converter at the second forced shift timing determined by the second determination unit. The switching control unit causes the winding switching device to switch from the second connection state to the first connection state after the AC current has changed. A winding switching system for a vehicle motor according to claim 1.

10. The second determination unit determines the timing at which the physical quantity related to the induced voltage becomes less than or equal to a second threshold corresponding to the output voltage of the battery as the second forced shift timing. A winding switching system for a vehicle motor according to claim 9.

11. The aforementioned winding switching system further includes an input device for receiving gear shift instructions from the driver. The aforementioned gear shift timing is the timing at which the input device receives the gear shift instruction from the driver. A winding switching system for a vehicle motor according to claim 1.

12. The gear shift timing is determined based on the rotational speed of the drive motor, the output torque, the acceleration instruction amount in the vehicle, and the braking instruction amount in the vehicle. A winding switching system for a vehicle motor according to claim 1.

13. The torque control unit gradually decreases or increases the effective current of the AC current output from the power converter from the gear shift timing. A winding switching system for a vehicle motor according to any one of claims 1 to 12.

14. The torque control unit changes the effective current in a ramp-like manner from the gear shift timing. A winding switching system for a vehicle motor according to claim 13.

15. The torque control unit changes the effective current of the AC current output from the power converter in a step-like manner based on the gear shift timing. A winding switching system for a vehicle motor according to any one of claims 1 to 12.

16. The torque control unit performs a pseudo-shift control process at a pseudo-shift timing different from the shift timing, which involves decreasing and then increasing the AC current output from the power converter. A winding switching system for a vehicle motor according to any one of claims 1 to 12.

17. A control device for controlling a drive motor that drives the wheels of a vehicle, A torque control unit that changes the output torque of the drive motor by changing the AC current output from a power converter that converts DC power output from the battery into AC power and supplies the AC power to the drive motor at a predetermined gear shift timing of the vehicle, A winding switching device for switching the connection state of multiple windings in the drive motor includes a switching control unit that, after the AC current changes, switches from a first connection state to a second connection state in which the drive motor outputs a lower torque than the first connection state at the same rotational speed, A determination unit that determines whether the induced voltage generated in the winding after the connection state of the winding is switched from the second connection state to the first connection state exceeds the output voltage of the battery, when the connection state of the plurality of windings is in the second connection state, When the determination unit determines that the induced voltage exceeds the output voltage of the battery, a prohibition unit prohibits the switching control unit from switching the connection state of the winding, Equipped with, Control device.

18. A method for controlling a vehicle motor, which is performed by a control device that controls a drive motor that drives the wheels of a vehicle, The steps include: changing the output torque of the drive motor by changing the AC current output from a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor at a predetermined gear shift timing of the vehicle; A winding switching device for switching the connection state of multiple windings in the drive motor, after the AC current changes, is configured to switch from a first connection state to a second connection state in which the drive motor outputs a lower torque than the first connection state at the same rotational speed. When the connection state of the plurality of windings is in the second connection state, the step of determining whether the induced voltage generated in the winding after the connection state of the winding is switched from the second connection state to the first connection state exceeds the output voltage of the battery, If it is determined that the induced voltage exceeds the output voltage of the battery, the step of prohibiting the switching control of the connection state of the winding, including, A method for controlling a vehicle motor.

19. A computer program used in a control device that controls the drive motors that drive the wheels of a vehicle, On the computer, The steps include: changing the output torque of the drive motor by changing the AC current output from a power converter that converts DC power output from a battery into AC power and supplies the AC power to the drive motor at a predetermined gear shift timing of the vehicle; A winding switching device for switching the connection state of multiple windings in the drive motor, after the AC current changes, is configured to switch from a first connection state to a second connection state in which the drive motor outputs a lower torque than the first connection state at the same rotational speed. When the connection state of the plurality of windings is in the second connection state, the step of determining whether the induced voltage generated in the winding after the connection state of the winding is switched from the second connection state to the first connection state exceeds the output voltage of the battery, If it is determined that the induced voltage exceeds the output voltage of the battery, the step of prohibiting the switching control of the connection state of the winding, To execute Computer program.

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