Winding switching system for vehicle motor, control device, method for controlling vehicle motor, and computer program

Abstract

This winding switching system for a vehicle motor comprises a drive motor, a control device, 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. When the drive motor is operating at a first rotation speed in the first connection state, if it is determined that the drive motor in the second connection state cannot output a first torque output by the drive motor, the control device continuously changes, over time, torque output by the drive motor in the first connection state up to a second torque, and causes the winding switching device to switch from the first connection state to the second connection state.

Description

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

[0001] This disclosure relates to a winding switching system for a vehicle motor, a control device, a control method for a vehicle motor, and a computer program. This application claims priority under Japanese application No. 2025-029278, filed on 26 February 2025, and incorporates all the contents contained herein.

[0002] Patent Document 1 discloses a winding switching device that can switch the winding connection state of a vehicle motor between a series connection state and a parallel connection state. In this device, when a gear shift instruction (i.e., a winding connection state switching instruction) is input, the AC current input to the motor is reduced, and after the AC current has decreased to zero, the winding connection state of the motor is switched between a series connection state and a parallel connection state. As a result of switching the winding connection state of the motor, the output torque of the motor is reduced, giving the driver a gear shifting sensation similar to that of a mechanical transmission.

[0003] International Publication No. 2024 / 075318

[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; 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, wherein the control device includes a processor, and the processor performs an operation including the steps of: when the drive motor is operating at a first rotation speed in the first connection state, determining whether a first torque output by the drive motor can be output by the drive motor operating at the first rotation speed in the second connection state; when it is determined that the first torque cannot be output by the drive motor operating at the first rotation speed in the second connection state, continuously changing, over time, the torque output by the drive motor in the first connection state to a second torque that can be generated by the drive motor operating at the first rotation speed in the second connection state; and when the torque output by the drive motor in the first connection state reaches the second torque, causing the winding switching device to execute switching from the first connection state to the second connection state.

[0005] Figure 1 is a diagram showing an example of the configuration of a winding switching system according to the first embodiment. Figure 2 is a block diagram showing an example of the hardware configuration of a control device according to the first embodiment. Figure 3 is a circuit diagram showing an example of the configuration of a winding switching device according to the first embodiment. Figure 4 is a graph showing an example of the characteristics of a motor according to the first embodiment. Figure 5 is a motor rotation speed-torque characteristic graph for explaining the first determination process by the control device according to the first embodiment. Figure 6A is a timing chart for explaining the first control process by the control device according to the first embodiment. Figure 6B is a timing chart for explaining the first control process by the control device according to the first embodiment. Figure 7A is a timing chart for explaining the second control process by the control device according to the first embodiment. Figure 7B is a timing chart for explaining the second control process by the control device according to the first embodiment. Figure 8 is a diagram for explaining a characteristic map. Figure 9 is a flowchart showing an example of the switching control process by the control device according to the first embodiment. Figure 10 is a circuit diagram showing an example of the configuration of a winding switching device according to the second embodiment.

[0006] For example, if the output torque in a series connection state cannot be achieved in a parallel connection state at the same rotational speed, a sudden torque fluctuation may occur when the motor winding connection state is switched from a series connection state to a parallel connection state, potentially impairing the comfort of operation. On the other hand, in the method disclosed in Patent Document 1, the motor's output torque drops to zero when the motor winding connection state is switched, which may cause discomfort during operation.

[0007] According to this disclosure, it is possible to reduce the discomfort felt by the driver when switching the winding state of the motor.

[0008] The embodiments of this disclosure are outlined below.

[0009] (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, 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, wherein the control device includes a processor, and the processor performs an operation that includes the steps of: determining whether the drive motor operating at a first rotational speed in the second connection state can output a first torque that the drive motor is outputting when the drive motor is operating at a first rotational speed in the first connection state; if it is determined that the drive motor operating at a first rotational speed in the second connection state cannot output the first torque, the step of continuously changing the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at a first rotational speed in the second connection state can generate; and causing the winding switching device to switch from the first connection state to the second connection state when the torque output by the drive motor in the first connection state reaches the second torque. As a result, when switching from the first winding state to the second winding state, the torque output by the motor changes continuously over time from the first torque to the second torque, thus reducing the discomfort felt by the operator when the motor winding state is switched.

[0010] (2) In (1) above, the first torque may be higher than the second torque. This prevents the motor's output torque from rapidly decreasing from the first torque to the second torque when the winding connection state is switched, thereby reducing the discomfort felt by the driver.

[0011] (3) In the step of changing the torque output by the drive motor up to the second torque over time in (1) or (2) above, the processor may change the torque output by the drive motor in the first connection state linearly over time. This allows the motor's output torque to change smoothly from the first torque to the second torque in accordance with the switching of the winding connection state, thereby reducing the discomfort felt by the driver.

[0012] (4) In any one of (1) to (3) above, the operation may further include the steps of: determining whether the drive motor operating at the second rotational speed in the first connection state can output the fourth torque that the drive motor will output at the second rotational speed after switching to the second connection state, when the drive motor is operating at the second rotational speed in the first connection state and outputting the third torque; causing the winding switching device to switch from the first connection state to the second connection state if it is determined that the drive motor operating at the second rotational speed in the first connection state cannot output the fourth torque; and continuously changing the torque output by the drive motor in the second connection state up to the fourth torque over time. As a result, when switching from the first winding state to the second winding state, the torque output by the motor changes continuously over time from the third torque to the fourth torque, thereby reducing the discomfort felt by the operator when switching the winding state of the motor.

[0013] (5) In (4) above, the third torque may be lower than the fourth torque. This prevents the motor's output torque from rapidly increasing from the third torque to the fourth torque when the winding connection state is switched, thereby reducing the discomfort felt by the driver.

[0014] (6) In the step of causing the winding switching device to switch from the first connection state to the second connection state in (4) or (5) above, the processor may cause the winding switching device to switch from the first connection state to the second connection state while maintaining the torque output by the drive motor at the third torque. This makes it possible to suppress torque fluctuations when switching the connection state of the motor windings and to reduce the discomfort felt by the driver.

[0015] (7) In any one of (4) to (6) above, in the step of changing the torque output by the drive motor over time up to the fourth torque, the processor may change the torque output by the drive motor in the second connection state linearly over time. This allows the motor's output torque to change smoothly from the third torque to the fourth torque in accordance with the switching of the winding connection state, thereby reducing the discomfort felt by the driver.

[0016] (8) 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 processor, which performs operations including: determining whether the drive motor operating at a first rotational speed in a second connection state can output a first torque output by the drive motor when the drive motor is operating at a first rotational speed in a first connection state among the connection states of a plurality of windings in the drive motor; if it is determined that the drive motor operating at a first rotational speed in the second connection state cannot output the first torque, continuously changing the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at a first rotational speed in the second connection state can generate; and causing a winding switching device to switch from the first connection state to the second connection state when the torque output by the drive motor in the first connection state reaches the second torque. As a result, when switching from the first winding state to the second winding state, the torque output by the motor changes continuously over time from the first torque to the second torque, thus reducing the discomfort felt by the operator when the motor winding state is switched.

[0017] (9) A method for controlling a vehicle motor according to this embodiment is a method for controlling a vehicle motor that drives the wheels of a vehicle, which is executed by a control device that controls a drive motor that drives the wheels of a vehicle, and includes the steps of: determining whether it is possible for the drive motor operating at a first rotational speed in a second connection state to output a first torque output by the drive motor when the drive motor is operating at a first rotational speed in a first connection state among the connection states of a plurality of windings of the drive motor; if it is determined that it is impossible for the drive motor operating at a first rotational speed in the second connection state to output the first torque, the steps of continuously changing the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at a first rotational speed in the second connection state can generate; and when the torque output by the drive motor in the first connection state reaches the second torque, the steps of causing a winding switching device to switch from the first connection state to the second connection state. As a result, when switching from the first winding state to the second winding state, the torque output by the motor changes continuously over time from the first torque to the second torque, thus reducing the discomfort felt by the operator when the motor winding state is switched.

[0018] (10) 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: determine whether it is possible for the drive motor operating at the first rotational speed in a second connection state to output a first torque output by the drive motor when the drive motor is operating at the first rotational speed in a first connection state among the connection states of a plurality of windings in the drive motor; if it is determined that it is impossible for the drive motor operating at the first rotational speed in the second connection state to output the first torque, continuously change the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at the first rotational speed in the second connection state can generate; and when the torque output by the drive motor in the first connection state reaches the second torque, cause the winding switching device to switch from the first connection state to the second connection state. As a result, when switching from the first winding state to the second winding state, the torque output by the motor changes continuously over time from the first torque to the second torque, thus reducing the discomfort felt by the operator when the motor winding state is switched.

[0019] 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.

[0020] <Details of Embodiments in This Disclosure> Hereinafter, details of embodiments of the present invention will be described with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0021] [1. First Embodiment] [1-1. Winding Switching System] Figure 1 is a diagram showing an example of the configuration of the winding switching system according to the first embodiment.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 when the motor 20 functions as a generator into DC power and charge the battery 40.

[0026] 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 the switches 31u, 32u, 31v, 32v, 31w, and 32w, DC power is converted into three-phase AC power. The 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).

[0027] 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 (DC current transformers) or shunt resistors.

[0028] 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.

[0029] 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 also 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.

[0030] The control device 50 is connected to a sensor 71 that detects the amount of depression of the brake pedal 70, and receives the 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 the detection signal output from the sensor 81. The amount of depression of the accelerator pedal 80 is the acceleration command value. That is, the control device 50 accepts the output signal from the sensor 81 as the acceleration command value.

[0031] 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.

[0032] 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 button for the driver to signal a gear shift. 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.

[0033] 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.

[0034] 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). In a specific example, the processor 501 is a multi-core processor. The processor 501 may also be a single-core processor. The processor 501 may include multiple processors or cores and be capable of performing parallel processing. The processor 501 is configured to execute computer programs. The processor 501 may include, for example, an ASIC (Application Specific Integrated Circuit) as part, or programmable hardware such as an FPGA (Field Programmable Gate Array) or a CPLD (Complex Programmable Logic Device) as part. The processor 501 may be, for example, an ASIC or programmable hardware. In this case, the ASIC or programmable hardware is configured to execute the same processing as the motor control program 510 without software.

[0035] 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.

[0036] I / F 504 is connected to the rotation sensor 201, torque sensor 202, sensor 71, sensor 81, and gear shift indicator 90. I / F 504 is, for example, an input / output interface or a communication interface. I / F 504 receives a detection signal of the rotation speed of the motor 20 output from the rotation sensor 201. I / F 504 receives a detection signal of the output torque of the motor 20 output from the torque sensor 202. I / F 504 receives a detection signal of the brake pedal depression amount output from sensor 71. I / F 504 receives a detection signal of the accelerator pedal depression amount (acceleration command value) output from sensor 81. I / F 504 receives a gear shift command signal output from gear shift indicator 90.

[0037] [1-2. Configuration of 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.

[0038] 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.

[0039] 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, in which case the parallel connection state corresponds to the second connection state. The parallel connection state is another example of the first connection state, in which case the series connection state corresponds to the second connection state.

[0040] Hereinafter, the connection relationship among the winding switching device 100, the power line 35u, and the motor 20 will be described as a representative example for the U phase. The description is omitted for the V phase and the W phase since the same applies thereto.

[0041] The power line 35u is connected to one end of the winding 21u. A power line 212u extends from the other end of the winding 21u. A power line 221u extends from one end of the winding 22u, and a power line 222u extends from the other end of the winding 22u.

[0042] The switching circuit 104u includes semiconductor relays 111u, 112u and 113u. The semiconductor relays 111u, 112u, 113u are, for example, IGBTs or power MOSFETs.

[0043] The power line 35u is drawn into the winding switching device 100. In the winding switching device 100, the power line 35u branches at an intermediate point and is connected to the first terminal of the semiconductor relay 111u. The second terminal of the semiconductor relay 111u is connected to the first terminal of the semiconductor relay 112u. A power line 221u extending from the winding 22u is connected to a connection point between the second terminal of the semiconductor relay 111u and the first terminal of the semiconductor relay 112u. The power lines 212u, 221u, and 222u extend from the motor 20 and are drawn into the winding switching device 100.

[0044] The second terminal of the semiconductor relay 112u is connected to the first terminal of the semiconductor relay 113u. A power line 212u extending from the winding 21u is connected to a connection point between the second terminal of the semiconductor relay 112u and the first terminal of the semiconductor relay 113u. The second terminal of the semiconductor relay 113u is connected to the power line 222u extending from the winding 22u.

[0045] When the semiconductor relays 111u and 113u are in an off state and the semiconductor relay 112u is in an on state, the windings 21u and 22u are connected in series. When the semiconductor relays 111u and 113u are in an on state and the semiconductor relay 112u is in an off state, the windings 21u and 22u are connected in parallel.

[0046] A signal line extending from a control circuit 103u is connected to each of the gate terminals of the semiconductor relays 111u, 112u, and 113u. A signal line extending from a control device 50 is connected to the control circuit 103u.

[0047] The control circuit 103u performs on / off control of the semiconductor relays 111u, 112u, and 113u by individually applying a gate voltage to the gate terminals of the semiconductor relays 111u, 112u, and 113u. Specifically, when the control circuit 103u receives an instruction from the control device 50 to switch the connection state of the windings 21u and 22u from the series connection state to the parallel connection state, the control circuit 103u sets the semiconductor relays 111u and 113u to an on state, and sets the semiconductor relay 112u to an off state. When the control circuit 103u receives an instruction from the control device 50 to switch the connection state of the windings 21u and 22u from the parallel connection state to the series connection state, the control circuit 103u sets the semiconductor relays 111u and 113u to an off state, and sets the semiconductor relay 112u to an on state.

[0048] The control circuit 103u is configured by, for example, a plurality of logic circuits (AND circuits, NOT circuits, latch circuits, etc.). In another example, the control circuit 103u is configured by a processor. For example, the control circuit 103u is configured by a one-chip microcomputer. The control circuit 103u may also be configured by an ASIC or programmable hardware.

[0049] [1-3. Functions of the Control Device] The output torque of the motor 20 is determined by the winding connection state, the rotation speed of the motor 20, and the acceleration command value. FIG. 4 is a graph showing an example of characteristics of the motor according to the first embodiment. In FIG. 4, the left graph shows the rotation speed-torque characteristic (N-T characteristic) of the motor. In the left graph, the vertical axis represents torque, and the horizontal axis represents rotation speed. Each of the center and right graphs shows the acceleration command value-torque characteristic of the motor. In the center and right graphs, the vertical axis represents torque, and the horizontal axis represents the acceleration command value.

[0050] From the N-T characteristics, it can be seen that, generally, the series connection state is a winding connection state that can output high torque in the low rotational speed range of the motor 20, and the parallel connection state is a winding connection state that can output low torque in the high rotational speed range of the motor 20. In other words, the series connection state is a low-speed, high-torque type winding connection state, and the parallel connection state is a high-speed, low-torque type winding connection state.

[0051] Switching the winding connection state from a series connection state to a parallel connection state is equivalent to shifting up in a mechanical transmission, and switching the winding connection state from a parallel connection state to a series connection state is equivalent to shifting down in a mechanical transmission. Switching the winding connection state from a series connection state to a parallel connection state is also called "electric shift up," and switching the winding connection state from a parallel connection state to a series connection state is also called "electric shift down."

[0052] In the example of the N-T characteristics in Figure 4, the solid line graph shows the maximum torque in the series connection state, i.e., the motor output torque when the acceleration command value input to the control device 50 is 100%. Similarly, the dashed line graph shows the maximum torque in the parallel connection state.

[0053] In the series connection state, the maximum torque T1 is generated in the rotational speed range from 0 to R1. In the series connection state, the maximum torque gradually decreases from T1 when the rotational speed exceeds R1, and becomes 0 at rotational speed R2. In the parallel connection state, the maximum torque T2 (<T1) is generated in the rotational speed range from 0 to R3 (>R1). In the parallel connection state, the maximum torque gradually decreases from T2 when the rotational speed exceeds R3, and becomes 0 at rotational speed R4. In the rotational speed range from 0 to Rx, the maximum torque in the series connection state is greater than the maximum torque in the parallel connection state. At rotational speed Rx, the maximum torque in the series connection state and the parallel connection state are the same, and in the rotational speed range greater than Rx, the maximum torque in the series connection state is less than the maximum torque in the parallel connection state.

[0054] The central graph in Figure 4 shows the acceleration command value-torque characteristics at rotational speed Ra (0 < Ra < R1). As mentioned above, the solid line graph on the left shows the N-T characteristics when the acceleration command value is 100%. When the acceleration command value changes at the same motor rotational speed, the amount of power supplied to the motor 20 changes according to the acceleration command value, and this changes the output torque. In the example in Figure 4, the relationship between the acceleration command value and torque is proportional. That is, in the series connection state, at rotational speed Ra, the torque changes linearly with respect to the acceleration command value in the range from 0 to T1. In the parallel connection state, at rotational speed Ra, the torque changes linearly with respect to the acceleration command value in the range from 0 to T2.

[0055] The graph on the right shows the acceleration command value-torque characteristics at rotational speed Rb (Rx < Rb < R3). In a series connection, at rotational speed Rb, the torque changes linearly with respect to the acceleration command value in the range from 0 to T3 (< T2). In a parallel connection, at rotational speed Rb, the torque changes linearly with respect to the acceleration command value in the range from 0 to T2.

[0056] The following functions are realized when the processor 501 executes the motor control program 510.

[0057] The processor 501 determines whether the motor 20, operating at a first rotational speed in the second connection state, can output the first torque that the motor 20 is outputting when the motor 20 is operating at a first rotational speed in the first connection state. Hereinafter, this process will also be referred to as the "first determination process".

[0058] The first determination process will now be explained in detail. When the connection state of the multiple windings 21u, 22u, 21v, 22v, 21w, and 22w (hereinafter also referred to as the "winding connection state") is in a series connection state, the processor 501 acquires the output torque of the motor 20 detected by the torque sensor 202, the rotational speed of the motor 20 detected by the rotation sensor 201, and the accelerator pedal depression amount (acceleration command value) detected by the sensor 81. The acquired output torque is the output torque of the motor 20 before switching the winding connection state, and this output torque will hereinafter also be referred to as the "measured torque". In this embodiment, the output torque of the motor 20 is measured by the torque sensor 202, but this is not limited to this. For example, the control device 50 may calculate the command torque value from the acceleration command value. In this configuration, the command torque value will be used instead of the measured torque. The output torque of the motor 20 after switching the winding connection state will also be referred to as the "estimated torque". The acquired rotational speed is the rotational speed of the motor 20 before switching the winding connection state, and this rotational speed will hereafter also be referred to as the "measured rotational speed". After switching the winding connection state to the parallel connection state, the processor 501 determines whether the motor 20 operating at the same rotational speed as the measured rotational speed before the switch can generate the same torque as the measured torque before the switch.

[0059] The same applies when switching the winding connection state from a parallel connection state to a series connection state. That is, when the winding connection state is a parallel connection state, the processor 501 acquires the measured torque, the measured rotational speed, and the acceleration command value. After switching the winding connection state to a series connection state, the processor 501 determines whether the motor 20 operating at the same rotational speed as the measured rotational speed before the switch can generate the same torque as the measured torque before the switch.

[0060] Figure 5 is an N-T characteristic graph illustrating the first determination process by the control device according to the first embodiment.

[0061] For example, in a series connection, the torque when the acceleration command value is 100% and the rotational speed is R1 is T1. In a parallel connection, the maximum torque when the rotational speed is R1 is T2, so the motor 20 cannot generate torque T1 when the rotational speed is R1 in a parallel connection. In other words, the processor 501 determines that, after switching the winding connection state from a series connection to a parallel connection, the motor 20 operating at the same rotational speed R1 as the measured rotational speed before the switch cannot generate the same torque T1 as the measured torque before the switch.

[0062] For example, in a series connection state, the torque when the acceleration command value is 50% and the rotational speed is R1 is T2. Since the maximum torque when the connection state is parallel and the rotational speed is R1 is T2, the motor 20 can generate torque T2 when the rotational speed is R1 in the parallel connection state. In other words, the processor 501 determines that after switching the winding connection state from a series connection state to a parallel connection state, the motor 20 operating at the same rotational speed R1 as the measured rotational speed before the switch can generate the same torque T2 as the measured torque before the switch.

[0063] For example, in a parallel connection state, the torque when the acceleration command value is 100% and the rotational speed is R5 (Rx < R5 < R3) is T2. In a series connection state and the rotational speed is R5, the maximum torque is T3 (< T2). Therefore, when the rotational speed is R5 in a series connection state, the motor 20 cannot generate torque T2. In other words, after switching the winding connection state from a parallel connection state to a series connection state, the processor 501 determines that the motor 20 operating at the same rotational speed R5 as the measured rotational speed before the switch cannot generate the same torque T2 as the measured torque before the switch.

[0064] For example, in a parallel connection state, when the acceleration command value is 50% and the rotational speed is R5, the torque is T4 (<T3). Since the maximum torque when the motor is connected in series and the rotational speed is R5 is T3, the motor 20 can generate torque T4 when the rotational speed is R5 in the series connection state. In other words, the processor 501 determines that, after switching the winding connection state from a parallel connection state to a series connection state, the motor 20 operating at the same rotational speed R5 as the measured rotational speed before the switch can generate the same torque T4 as the measured torque before the switch.

[0065] Returning to Figure 1, if it is determined that the motor 20 operating at the first rotational speed in the second connection state is unable to output the first torque, the processor 101 continuously changes the torque output by the motor 20 in the first connection state over time until it reaches the second torque that the motor 20 operating at the first rotational speed in the second connection state can generate. When the torque output by the motor 20 in the first connection state reaches the second torque, the processor 101 causes the winding switching device 100 to switch from the first connection state to the second connection state. Hereinafter, this process will also be referred to as the "first control process".

[0066] The first control process will now be described in detail. Figures 6A and 6B are timing charts for illustrating the first control process by the control device according to the first embodiment. In Figures 6A and 6B, the vertical axis represents torque, and the horizontal axis represents time.

[0067] Figure 6A shows the time change of torque due to the first control process when switching the winding connection state from a series connection state to a parallel connection state, when the acceleration command value is 100% and the rotational speed is R1 in a series connection state.

[0068] If, after switching the winding connection state from a series connection state to a parallel connection state, it is determined that the motor 20 operating at the same rotational speed as the measured rotational speed before the switch cannot generate the same torque as the measured torque before the switch, the processor 501 maintains the series connection state and continuously changes the torque output by the motor 20 over time to an estimated torque that the motor 20 operating at the same rotational speed as the measured rotational speed after switching the winding connection state to a parallel connection state can generate.

[0069] More specifically, if a negative judgment result is obtained in the first judgment process, the measured torque before switching is higher than the maximum output torque of the motor 20 operating at the same rotational speed as the measured rotational speed before switching. Therefore, the measured torque is higher than the estimated torque. Accordingly, in the first control process, the processor 501 continuously decreases the output torque of the motor 20 over time while maintaining the winding connection state before switching.

[0070] In Figure 6A, the measured torque before switching the winding connection state is T1, and the estimated torque after switching the winding connection state is T2. In the first control process, the processor 501 decreases the output torque of the motor 20 in series connection state from T1 to T2 in time from t11. In the example in Figure 6A, the output torque changes linearly in time from T1 to T2.

[0071] At time t12, the output torque of the motor 20 reaches T2, and immediately after the output torque reaches T2, the processor 501 switches the winding connection state from series connection to parallel connection state. When the winding connection state is switched, the processor 501 ends the forced torque reduction. As a result, the torque fluctuates smoothly in conjunction with the switching of the winding connection state.

[0072] Figure 6B shows the time change of torque due to the first control process when switching the winding connection state from parallel to series connection state in a parallel connection state, where the acceleration command value is 100% and the rotational speed is R5.

[0073] If, after switching the winding connection state from parallel to series, it is determined that the motor 20 operating at the same rotational speed as before the switch cannot generate the same torque as before the switch, the processor 501 maintains the parallel connection state and continuously changes the torque output by the motor 20 over time to an estimated torque that the motor 20 operating at the same rotational speed as before the switch can generate. As described above, in this case the measured torque is higher than the estimated torque. Therefore, in the first control process, the processor 501 maintains the winding connection state before the switch and continuously decreases the output torque of the motor 20 over time.

[0074] In Figure 6B, the measured torque before switching the winding connection state is T2, and the estimated torque after switching the winding connection state is T3. In the first control process, the processor 501 decreases the output torque of the motor 20 in the parallel connection state from T2 to T3 in time from time t21. In the example in Figure 6B, the output torque changes linearly in time from T2 to T3.

[0075] At time t22, the output torque of the motor 20 reaches T3, and immediately after the output torque reaches T3, the processor 501 switches the winding connection state from parallel to series. When the winding connection state is switched, the processor 501 terminates the forced torque reduction. As a result, the torque fluctuates smoothly in conjunction with the switching of the winding connection state.

[0076] Returning to Figure 1, the processor 501 determines whether the motor 20 operating at the second rotational speed in the first connection state can output the fourth torque that the motor 20 will output at the second rotational speed after switching to the second connection state, given that the motor 20 is operating at the second rotational speed and outputting the third torque in the first connection state. Hereafter, this process will also be referred to as the "second determination process".

[0077] The second determination process will now be explained in detail. When the winding connection state is in series connection state, the measured torque, measured rotational speed, and acceleration command value are obtained. After switching the winding connection state to parallel connection state, the processor 501 determines whether the motor 20 operating at the same rotational speed as before the switch can generate the same torque (estimated torque) as the motor 20 operating at the same rotational speed as before the switch.

[0078] The same applies when switching the winding connection state from a parallel connection state to a series connection state. That is, when the winding connection state is a parallel connection state, the processor 501 acquires the measured torque, the measured rotational speed, and the acceleration command value. After switching the winding connection state to a series connection state, the processor 501 determines whether the motor 20 operating at the same rotational speed as before the switch can generate the same torque as the estimated torque output by the motor 20 operating at the same rotational speed as before the switch.

[0079] Refer to Figure 5. For example, consider the case where the connection is switched from a parallel state to a series state when the acceleration command value is 100% and the rotational speed is R1. In the parallel state, the torque when the acceleration command value is 100% and the rotational speed is R1 is T2. That is, the maximum torque at rotational speed R1 in the parallel state is T2. In the series state, the torque when the acceleration command value is 100% and the rotational speed is R1 is T1 (>T2), and the motor 20 cannot generate torque T1 when the rotational speed is R1 in the parallel state. In this case, the processor 501 determines that the estimated torque T1 generated by the motor 20 operating at the same rotational speed R1 as the measured rotational speed after switching the winding connection state from parallel to series cannot be generated by the motor 20 before the winding connection state was switched.

[0080] For example, consider the case where the connection is switched from a parallel state to a series state when the acceleration command value is 50% and the rotational speed is R1. In the parallel state, the torque when the acceleration command value is 50% and the rotational speed is R1 is T4, and the maximum torque when the rotational speed is R1 is T2. In the series state, the torque when the acceleration command value is 50% and the rotational speed is R1 is T2, which matches the maximum torque of the motor 20 when the rotational speed is R1 in the parallel state. In this case, the processor 501 determines that the motor 20 before the switch in the winding connection state can generate the estimated torque T2 generated by the motor 20 operating at the same rotational speed R1 as the measured rotational speed after switching the winding connection state from a parallel state to a series state.

[0081] For example, consider the case where the winding connection state is switched from a series connection state to a parallel connection state when the acceleration command value is 100% and the rotational speed is R5. In the series connection state, the torque when the acceleration command value is 100% and the rotational speed is R5 is T3. That is, the maximum torque when the rotational speed is R5 in the series connection state is T3. In the parallel connection state, the torque when the acceleration command value is 100% and the rotational speed is R5 is T2 (>T3), and the motor 20 cannot generate torque T2 when the rotational speed is R5 in the series connection state. In this case, the processor 501 determines that the estimated torque T2 generated by the motor 20 operating at the same rotational speed R5 as the measured rotational speed after switching the winding connection state from a series connection state to a parallel connection state cannot be generated by the motor 20 before the winding connection state was switched.

[0082] For example, consider the case where the winding connection state is switched from a series connection state to a parallel connection state when the acceleration command value is 50% and the rotational speed is R5. In the series connection state, the torque when the acceleration command value is 50% and the rotational speed is R5 is T5 (<T4), and the maximum torque when the rotational speed is R5 is T3. In the parallel connection state, the torque when the acceleration command value is 50% and the rotational speed is R5 is T4, which is smaller than the maximum torque T3 of the motor 20 when the rotational speed is R5 in the series connection state. In this case, the processor 501 determines that the motor 20 before the switch in the winding connection state can generate the estimated torque T4 that the motor 20 would generate if it operated at the same rotational speed R5 as the measured rotational speed after switching the winding connection state from a series connection state to a parallel connection state.

[0083] Returning to Figure 1, if it is determined that the motor 20 operating at the second rotational speed in the first connection state is unable to output the fourth torque, the processor 501 instructs the winding switching device 100 to switch from the first connection state to the second connection state. When the connection state is switched from the first to the second connection state, the processor 501 continuously changes the torque output by the motor 20 in the second connection state up to the fourth torque over time. Hereinafter, this process will also be referred to as the "second control process".

[0084] The second control process will now be explained in detail. Figures 7A and 7B are timing charts for illustrating the second control process by the control device according to the first embodiment. In Figures 7A and 7B, the vertical axis represents torque, and the horizontal axis represents time.

[0085] Figure 7A shows the time change of torque due to the second control process when switching the winding connection state from a parallel connection state to a series connection state, when the acceleration command value is 100% and the rotational speed is R1 in a parallel connection state.

[0086] Before switching the winding connection state from parallel to series, if it is determined that the motor 20 operating at the measured rotational speed cannot generate the same torque as the estimated torque output by the motor 20 operating at the same rotational speed as the measured rotational speed after the switch, the processor 501 switches the winding connection state from parallel to series. After the winding connection state is switched from parallel to series, the processor 501 continuously changes the torque output by the motor 20 over time to the estimated torque that the motor 20 operating at the same rotational speed as the measured rotational speed after the winding connection state is switched to series.

[0087] More specifically, if a negative result is obtained in the second determination process, the maximum output torque of the motor 20 before switching is lower than the output torque of the motor 20 operating in the winding connection state (series connection state) after switching, at the same speed as the measured rotational speed before switching, according to the same acceleration command value as before switching. Therefore, the measured torque is lower than the estimated torque. Accordingly, in the second control process, the processor 501 continuously increases the output torque of the motor 20 over time after performing the winding connection state switch.

[0088] In Figure 7A, the measured torque before switching the winding connection state is T2, and the estimated torque after switching the winding connection state is T1. In the second control process, the processor 501 switches the winding connection state from parallel to series at time t31, and immediately after switching the winding connection state, it increases the output torque of the series-connected motor 20 from T2 to T1 over time. When the output torque of the motor 20 reaches T1 at time t32, the processor 501 terminates the forced torque increase. In the example of Figure 7A, the output torque changes linearly over time from T2 to T1. As a result, the torque fluctuates smoothly with the switching of the winding connection state. However, in the first control process, the output torque of the motor 20 may be changed in a curve over time.

[0089] Figure 7B shows the time change of torque due to the second control process when switching the winding connection state from a series connection state to a parallel connection state, when the acceleration command value is 100% and the rotational speed is R5 in a series connection state.

[0090] Before switching the winding connection state from series to parallel, if it is determined that the motor 20 operating at the measured rotational speed cannot generate the same torque as the estimated torque output by the motor 20 operating at the same rotational speed as the measured rotational speed after the switch, the processor 501 switches the winding connection state from series to parallel. After the winding connection state is switched from series to parallel, the processor 501 continuously changes the torque output by the motor 20 over time to the estimated torque that the motor 20 operating at the same rotational speed as the measured rotational speed after the winding connection state is switched to parallel.

[0091] In Figure 7B, the maximum output torque of the motor 20 before switching the winding connection state is T3, and the estimated torque of the motor 20 after switching the winding connection state is T2. In the second control process, the processor 501 switches the winding connection state at time t41, and immediately after switching the winding connection state, it increases the output torque of the motor 20 from T3 to T2 over time. When the output torque of the motor 20 reaches T2 at time t42, the processor 501 terminates the forced torque increase. In the example of Figure 7B, the output torque changes linearly over time from T3 to T2. As a result, the torque fluctuates smoothly in conjunction with the switching of the winding connection state. However, in the second control process, the output torque of the motor 20 may also be changed in a curve over time.

[0092] For example, the non-volatile memory 502 may store a characteristic map showing the correspondence between torque, rotational speed, and acceleration command value. Figure 8 is a diagram illustrating the characteristic map. The characteristic map contains information showing the N-T characteristics described above. The characteristic map has a first specific switching range and a second specific switching range mapped to it.

[0093] The first specific switching range is the range in which, at the same rotational speed, the torque in the series connection state is greater than the maximum torque in the parallel connection state. The first specific switching range is one of the ranges that indicates the target of execution of the first control process and the second control process. That is, when switching from a series connection state to a parallel connection state, if the measured torque and measured rotational speed are included in the first specific switching range, the processor 501 executes the first control process. When switching from a parallel connection state to a series connection state, if the estimated torque and measured rotational speed are included in the first specific switching range, the processor 501 executes the second control process.

[0094] The second specific switching range is the range in which, at the same rotational speed, the torque in the parallel connection state is greater than the maximum torque in the series connection state. The second specific switching range is one of the ranges that indicates the target of execution of the first control process and the second control process. That is, when switching from a parallel connection state to a series connection, if the measured torque and measured rotational speed are included in the second specific switching range, the processor 501 executes the first control process. When switching from a series connection state to a parallel connection, if the estimated torque and measured rotational speed are included in the second specific switching range, the processor 501 executes the second control process.

[0095] Furthermore, the range where the rotational speed exceeds R4 is a range where the motor 20 cannot operate in the series connection state, and therefore the winding connection state cannot be switched, and is not included in the second specific switching range.

[0096] The processor 501 refers to the characteristic map and executes a first determination process and a second determination process. When switching from a series connection to a parallel connection, if the measured torque and measured rotational speed fall within the first specific switching range, the processor 501 determines in the first determination process that a negative determination result will be obtained. When switching from a series connection to a parallel connection, if the estimated torque and measured rotational speed fall within the second specific switching range, the processor 501 determines in the second determination process that a negative determination result will be obtained.

[0097] When switching from a parallel connection to a series connection, if the measured torque and measured rotational speed fall within the second specific switching range, the processor 501 determines in the first determination process that a negative determination result will be obtained. When switching from a parallel connection to a series connection, if the estimated torque and measured rotational speed fall within the first specific switching range, the processor 501 determines in the second determination process that a negative determination result will be obtained.

[0098] The processor 501 can also perform the first determination process without using the characteristic map. In the first determination process, the processor 501 obtains the measured torque before the winding connection state is switched and determines the maximum torque of the motor 20 after the winding connection state is switched from the measured rotational speed of the motor 20 at that time. The processor 501 compares the measured torque with the maximum torque and determines that if the measured torque is greater than the maximum torque, the motor 20 operating at the same rotational speed as the measured rotational speed before the switch after the winding connection state is switched will not be able to generate the same torque as the measured torque before the switch. If the measured torque is less than or equal to the maximum torque, the processor 501 determines that the motor 20 operating at the same rotational speed as the measured rotational speed before the switch after the winding connection state is switched will be able to generate the same torque as the measured torque before the switch.

[0099] The processor 501 can also perform a second determination process without using a characteristic map. In the second determination process, the processor 501 obtains the measured torque before the winding connection state is switched and the measured rotational speed of the motor 20. The processor 501 identifies the maximum torque of the motor 20 before the winding connection state is switched and estimates the output torque of the motor 20 after the winding connection state is switched. The processor 501 compares the estimated torque with the maximum torque, and if the estimated torque is greater than the maximum torque, it determines that the motor 20 before the winding connection state is switched cannot generate the torque that the motor 20 would output if it were operating at the same rotational speed as the measured rotational speed after the winding connection state is switched. If the estimated torque is less than or equal to the maximum torque, the processor 501 determines that the motor 20 before the winding connection state is switched can generate the torque that the motor 20 would output if it were operating at the same rotational speed as the measured rotational speed after the winding connection state is switched.

[0100] The winding connection status switching instruction is a gear shift instruction output from the gear shift indicator 90. In vehicles equipped with a gear shift indicator 90, when the driver uses the gear shift indicator 90 to instruct a gear shift, the gear shift instruction is input to the control device 50.

[0101] In other examples, a gear shift command is generated 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 command value), and the amount the accelerator pedal 80 is pressed (acceleration command value). That is, an automatic gear shift control device (not shown) in the vehicle generates a gear shift command 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 command value), and the amount the accelerator pedal 80 is pressed (acceleration command value), and the generated gear shift command is input to the control device 50.

[0102] [1-4. Operation of the Winding Switching System] Next, the operation of the winding switching system 10 will be described. The control device 50 performs the following switching control process by having the processor 501 execute the motor control program 510.

[0103] Figure 9 is a flowchart showing an example of a switching control process by the control device according to the first embodiment.

[0104] When the driver performs an electrical gear change of the vehicle, they operate the gear shift indicator 90 to input an electrical gear change instruction to the vehicle, that is, an instruction to switch the winding connection state (an instruction to switch from a series connection state to a parallel connection state, or an instruction to switch from a parallel connection state to a series connection state). The processor 501 receives the instruction to switch the winding connection state (step S101).

[0105] The processor 501 obtains the measured torque from the detection signal of the torque sensor 202, the measured rotational speed of the motor 20 from the detection signal of the rotation sensor 201, and the amount of depression of the accelerator pedal 80 (acceleration command value) from the detection signal of the sensor 81 (step S102).

[0106] The processor 501 estimates the motor output torque after the winding connection state is switched based on the measured rotational speed and the acceleration command value (step S103). The measured torque may also be used to calculate the motor output torque.

[0107] The processor 501 performs a first determination process (step S104). That is, after switching the winding connection state, the processor 501 determines whether the motor 20 operating at the same rotational speed as the measured rotational speed before the switch can generate the same torque as the measured torque before the switch.

[0108] If a negative result is obtained in the first determination process, that is, if it is determined that after switching the winding connection state, the motor 20 operating at the same rotational speed as the measured rotational speed before the switch cannot generate the same torque as the measured torque before the switch (NO in step S104), the processor 501 executes the first control process. That is, the processor 501 reduces the output torque of the motor 20 before switching the winding connection state (step S105) and determines whether the motor's output torque matches the estimated torque (step S106). If the motor's output torque does not match the estimated torque (NO in step S106), the processor 501 returns to step S105. If the motor's output torque matches the estimated torque (YES in step S106), the processor 501 outputs a winding connection state switching instruction to the winding switching device 100 (step S107). As a result, the connection states of windings 21u, 22u, 21v, 22v, 21w, and 22w are switched. This completes the switching control process.

[0109] If a positive result is obtained in the first determination process, that is, if it is determined that after switching the winding connection state, the motor 20 operating at the same rotational speed as the measured rotational speed before the switch can generate the same torque as the measured torque before the switch (YES in step S104), the processor 501 executes the second determination process (step S108). That is, the processor 501 determines whether the motor 20 before the winding connection state switch can generate the same torque (estimated torque) as the torque output by the motor 20 operating at the same rotational speed as the measured rotational speed before the switch after switching the winding connection state.

[0110] If a negative result is obtained in the second determination process, that is, if it is determined that the motor 20 before the winding connection state switching cannot generate the same torque as the estimated torque (NO in step S108), the processor 501 executes the second control process. That is, the processor 501 outputs a winding connection state switching instruction to the winding switching device 100 (step S109). As a result, the connection states of windings 21u, 22u, 21v, 22v, 21w, and 22w are switched. Furthermore, the processor 501 increases the output torque of the motor 20 (step S110) and determines whether the motor's output torque matches the estimated torque (step S111). If the motor's output torque does not match the estimated torque (NO in step S111), the processor 501 returns to step S110. If the motor's output torque matches the estimated torque (YES in step S111), the switching control process ends.

[0111] If a positive result is obtained in the second determination process, that is, if it is determined that the motor 20 before the winding connection state is switched can generate the same torque as the estimated torque (YES in step S108), the processor 501 outputs a winding connection state switching instruction to the winding switching device 100 (step S109). As a result, the connection states of windings 21u, 22u, 21v, 22v, 21w, and 22w are switched. The switching control process is then completed.

[0112] [2. Second Embodiment] The winding switching device according to the second embodiment switches the connection state of the motor's windings between a fully connected state in which all of the windings are connected and a partially connected state in which some of the windings are connected.

[0113] Figure 10 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, but may be three or more.

[0114] The winding switching device 100A switches the connection state of windings 24u, 25u, 24v, 25v, 24w, and 25w between a fully connected state and a partially connected state for each phase. The winding switching device 100A includes control circuits 103u, 103v, and 103w, and switching circuits 140u, 140v, and 140w.

[0115] The switching circuits 140u, 140v, and 140w switch 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 a low-speed, high-torque type connection state, while the partially connected state is a high-speed, low-torque type connection state.

[0116] 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 winding 24u and winding 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] In switching circuit 140u, the first terminal of semiconductor relay 141u is connected to power line 242u, and the second terminal is connected to power line 243u. The first terminal of semiconductor relay 142u is connected to power line 252u, and the 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.

[0121] 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.

[0122] 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, so the same reference numerals are used for the same components and their descriptions are omitted.

[0123] 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.

[0124] [3. Modified Examples] In the second embodiment, instead of switching the winding connection state by the winding switching device 100A, for example, the power converter 30 may be provided with a function to supply AC current to all windings 24u, 25u, 24v, 25v, 24w, and 25w, and a function to supply AC power only to windings 24u, 24v, and 24w, and the winding connection state may be switched between a fully connected state and a partially connected state by switching the function of the power converter 30.

[0125] [4. 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 of the claims and all modifications within that scope.

[0126] 10 Winding switching system 20 Motor (drive motor) 21u, 22u, 21v, 22v, 21w, 22w Winding 23 Neutral point 25 Power line 30 Power converter 31u, 32u, 31v, 32v, 31w, 32w Switch 33u, 33v, 33w Current sensor 34u, 34v, 34w Voltage sensor 35u, 35v, 35w Power line 40 Battery 50, 50A Control device 501 Processor 502 Non-volatile memory 503 Volatile memory 504 Interface (I / F) 510 Motor control program 60 Wheel 70 Brake pedal 71 Sensor 80 Accelerator pedal 81 Sensor 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 relay 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 relay 241u, 242u, 243u, 251u, 252u, 253u, 241v, 242v, 243v, 251v, 252v, 253v, 241w, 242w, 243w, 251w, 252w, 253w Power line

Claims

1. A vehicle comprises: a drive motor for driving the wheels of a vehicle; a control device for controlling the drive motor; and a winding switching device for switching the connection state of a plurality of windings in the drive motor between a first connection state and a second connection state, wherein the control device includes a processor, and the processor performs operations including: determining whether the drive motor operating at a first rotational speed in the second connection state can output a first torque when the drive motor is operating at a first rotational speed in the first connection state; if it is determined that the drive motor operating at a first rotational speed in the second connection state cannot output the first torque, continuously changing the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at a first rotational speed in the second connection state can generate; and causing the winding switching device to switch from the first connection state to the second connection state when the torque output by the drive motor in the first connection state reaches the second torque. A winding switching system for vehicle motors.

2. The winding switching system according to claim 1, wherein the first torque is higher than the second torque.

3. In the step of changing the torque output by the drive motor up to the second torque over time, the processor changes the torque output by the drive motor in the first connection state linearly over time, the winding switching system according to claim 1 or claim 2.

4. The winding switching system according to any one of claims 1 to 3, further comprising: determining whether the drive motor operating at the second rotational speed in the first connection state can output a fourth torque, which the drive motor will output at the second rotational speed after switching to the second connection state, when the drive motor is operating at the second rotational speed in the first connection state and outputting a third torque; causing the winding switching device to switch from the first connection state to the second connection state if it is determined that the drive motor operating at the second rotational speed in the first connection state cannot output the fourth torque; and continuously changing the torque output by the drive motor in the second connection state up to the fourth torque over time.

5. The winding switching system according to claim 4, wherein the third torque is lower than the fourth torque.

6. The winding switching system according to claim 4 or 5, wherein in the step of causing the winding switching device to switch from the first connection state to the second connection state, the processor causes the winding switching device to switch from the first connection state to the second connection state while maintaining the torque output by the drive motor at the third torque.

7. In the step of changing the torque output by the drive motor over time up to the fourth torque, the processor changes the torque output by the drive motor in the second connection state linearly over time, according to any one of claims 4 to 6.

8. A control device for controlling a drive motor that drives the wheels of a vehicle, comprising a processor, the processor performing an operation including: determining whether the drive motor, operating at a first rotational speed in a second connection state, can output a first torque when the drive motor is operating at a first rotational speed in a first connection state among the connection states of a plurality of windings in the drive motor; if it is determined that the drive motor, operating at a first rotational speed in the second connection state, cannot output the first torque, continuously changing the torque output by the drive motor in the first connection state to a second torque that the drive motor, operating at a first rotational speed in the second connection state, can generate; and causing a winding switching device to switch from the first connection state to the second connection state when the torque output by the drive motor in the first connection state reaches the second torque.

9. 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, comprising: determining whether it is possible for the drive motor operating at a first rotational speed in a second connection state to output a first torque output by the drive motor when the drive motor is operating at a first rotational speed in a first connection state among the connection states of a plurality of windings in the drive motor; if it is determined that it is impossible for the drive motor operating at a first rotational speed in the second connection state to output the first torque, continuously changing the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at a first rotational speed in the second connection state can generate; and when the torque output by the drive motor in the first connection state reaches the second torque, causing a winding switching device to switch from the first connection state to the second connection state.

10. A computer program used by a control device that controls a drive motor that drives the wheels of a vehicle, the computer program to perform the following steps: determine whether the drive motor operating at a first rotational speed in a second connection state can output a first torque output by the drive motor when the drive motor is operating at a first rotational speed in a first connection state among the connection states of a plurality of windings in the drive motor; if it is determined that the drive motor operating at a first rotational speed in the second connection state cannot output the first torque, continuously change the torque output by the drive motor in the first connection state to a second torque that the drive motor operating at a first rotational speed in the second connection state can generate; and when the torque output by the drive motor in the first connection state reaches the second torque, cause the winding switching device to switch from the first connection state to the second connection state.

Images