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

Abstract

This reduces the discomfort felt by the driver when switching the motor winding state while an acceleration command is being given. [Solution] A winding switching system for a vehicle motor includes a drive motor, a control device, 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, upon receiving a switching instruction from the first connection state to the second connection state, performs an operation including the steps of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, and prohibiting the winding switching device from switching from the first connection state to the second connection state while the torque difference exceeds the threshold.

Description

[Technical Field]

[0001] The present 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. [Background Art]

[0002] Patent Document 1 discloses a winding switching device capable of switching the connection state of windings of a vehicle motor between a series connection state and a parallel connection state, wherein the alternating current input to the motor is reduced at the timing when a shift instruction (i.e., an instruction to switch the winding connection state) is input, and after the alternating current amount decreases to zero, the connection state of the motor windings is switched between the series connection state and the parallel connection state. Accordingly, the output torque of the motor is reduced along with the switching of the connection state of the motor windings, thereby providing the driver with a shift feeling similar to that of a mechanical transmission. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] International Publication No. WO2024 / 075318 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In a rotational speed region where there is a large difference in motor output torque between the series connection state and the parallel connection state, if the connection state of the motor windings is switched while an acceleration command is being given (i.e., the accelerator opening is large), large torque fluctuation will occur, which may impair driving comfort. On the other hand, in the method disclosed in Patent Document 1, although an acceleration command is given, the output torque of the motor drops to zero when switching the connection state of the motor windings, which impairs the driver's acceleration feeling and may cause a sense of discomfort during driving. [Means for Solving the Problem]

[0005] A winding switching system for a vehicle motor according to one aspect of the present disclosure 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 when the processor receives a switching instruction from the first connection state to the second connection state, it performs an operation including the step of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, and the step of prohibiting the winding switching device from switching from the first connection state to the second connection state while the torque difference exceeds the threshold. [Effects of the Invention]

[0006] According to this disclosure, it is possible to reduce the discomfort felt by the driver when switching the winding state of the motor while an acceleration command is being given. [Brief explanation of the drawing]

[0007] [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 the control device according to the first embodiment. [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 graph showing an example of the characteristics of the motor according to the first embodiment. [Figure 5] Figure 5 shows the range in which winding switching is permitted in the motor according to the first embodiment. [Figure 6] Figure 6 is a flowchart showing an example of switching control processing by the control device according to the first embodiment. [Figure 7] Figure 7 is a diagram illustrating the switching of the winding connection state of the motor according to the second embodiment. [Figure 8] Figure 8 is a flowchart showing an example of a switching control process by the control device according to the second embodiment. [Figure 9] Figure 9 is a circuit diagram showing an example of the configuration of a winding switching device according to the third embodiment. [Modes for carrying out the invention]

[0008] <Summary of the embodiments of this disclosure> 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. The control device includes a processor, and when the processor receives a switching instruction from the first connection state to the second connection state, it performs an operation that includes the steps of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, and prohibiting the winding switching device from switching from the first connection state to the second connection state while the torque difference exceeds the threshold. This makes it possible to reduce the discomfort felt by the driver when the motor winding state is switched by prohibiting the switching of the motor winding state when the torque difference between the first connection state and the second connection state is large when an acceleration command is given.

[0010] (2) In (1) above, the operation may further include the step of causing the winding switching device to switch from the first connection state to the second connection state after transitioning from a first torque state in which the torque difference exceeds the threshold to a second torque state in which the torque difference is less than or equal to the threshold. This makes it possible to switch the motor winding state after the torque difference has decreased, and reduces the discomfort felt by the driver when switching the motor winding state.

[0011] (3) In (1) or (2) above, the determination step may include determining whether the torque difference exceeds the threshold based on the acceleration command of the vehicle or the output torque of the drive motor and the rotational speed of the drive motor. This eliminates the need to calculate the output torque of the motor in the second connection state when the motor windings are in the first connection state, and allows for a simpler process to determine whether the torque difference exceeds the threshold.

[0012] (4) In (1) or (2) above, the determination step may include determining whether the torque difference exceeds the threshold by determining whether the torque difference exceeds the threshold by determining whether the measured value of the vehicle's acceleration command and the measured value of the drive motor's output torque and the measured value of the drive motor's rotation speed are included in the switchable range defined in the correspondence information that shows the correspondence between the acceleration command value and the output torque of the drive motor and the rotation speed of the drive motor. This makes it possible to determine whether the torque difference exceeds the threshold by a simple process using the measured value of the acceleration command or output torque and the measured value of the motor's rotation speed.

[0013] (5) In any one of (1) to (4) above, the operation may further include the step of causing the winding switching device to switch from the first connection state to the second connection state based on a specific timing in which the magnitude of the first output torque and the magnitude of the second output torque are reversed when the rotational speed of the drive motor increases over time and the first output torque decreases over time in the first connection state. This prevents a decrease in torque when the winding connection state is switched while the vehicle is accelerating, and reduces the discomfort felt by the driver.

[0014] (6) 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, when it receives an instruction to switch the connection state of a plurality of windings in the drive motor from a first connection state to a second connection state, performs an operation that includes the steps of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, and prohibiting the switching from the first connection state to the second connection state while the torque difference exceeds the threshold. As a result, when an acceleration command is given and the torque difference between the first connection state and the second connection state is large, the switching of the motor winding state is prohibited, thereby reducing the discomfort felt by the driver when the motor winding state is switched.

[0015] (7) A control method for a vehicle motor according to the present embodiment is a control method for a vehicle motor executed by a control device that controls a drive motor that drives wheels of a vehicle, the method comprising: when an instruction to switch a connection state of a plurality of windings in the drive motor from a first connection state to a second connection state is received, determining whether a torque difference, which is a difference between a first output torque of the drive motor in the first connection state and a second output torque of the drive motor in the second connection state, exceeds a threshold value; and prohibiting switching from the first connection state to the second connection state while the torque difference exceeds the threshold value. Accordingly, in a state where an acceleration command is issued, when the torque difference between the first connection state and the second connection state is large, prohibiting switching of the winding connection state of the motor makes it possible to reduce discomfort felt by the driver when switching the winding connection state of the motor.

[0016] (8) A computer program according to the present embodiment is a computer program used by a control device that controls a drive motor that drives wheels of a vehicle, the computer program causing a computer to execute: when an instruction to switch a connection state of a plurality of windings in the drive motor from a first connection state to a second connection state is received, determining whether a torque difference, which is a difference between a first output torque of the drive motor in the first connection state and a second output torque of the drive motor in the second connection state, exceeds a threshold value; and prohibiting switching from the first connection state to the second connection state while the torque difference exceeds the threshold value. Accordingly, in a state where an acceleration command is issued, when the torque difference between the first connection state and the second connection state is large, prohibiting switching of the winding connection state of the motor makes it possible to reduce discomfort felt by the driver when switching the winding connection state of the motor.

[0017] The present disclosure can be implemented not only as a winding switching system for a vehicle motor having the above-described characteristic configuration, but also as a control device included in a winding switching system for a vehicle motor, or as a control method for a vehicle motor including steps of characteristic processing performed in the control device. The present disclosure can be implemented as a computer program that causes a computer to function as a control device, or some or all of the control device can be implemented as a semiconductor integrated circuit.

[0018] <Details of Embodiments of the Present Disclosure> Hereinafter, details of embodiments of the present invention will be described with reference to the drawings. Note that at least part of the embodiments described below may be arbitrarily combined with each other.

[0019] [1. First Embodiment] [1-1. Winding Switching System] FIG. 1 is a diagram showing an example configuration of the winding switching system according to the first embodiment.

[0020] The winding switching system 10 is mounted on a vehicle propelled by a motor, such as an electric vehicle or a plug-in hybrid vehicle (hereinafter referred to as an "electric vehicle"). 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.

[0021] The motor 20 is a traveling motor that generates propulsive force for the electric vehicle. That is, the motor 20 is connected to wheels 60 and is a drive motor that drives the wheels 60. The motor 20 is driven by three-phase AC power. An example of the motor 20 is a permanent magnet synchronous motor.

[0022] The battery 40 is a battery for supplying electric power to drive the motor 20. The battery 40 is a secondary battery, for example, a lithium-ion battery.

[0023] 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.

[0024] 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).

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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. In other words, the control device 50 accepts the output signal from the sensor 81 as the acceleration command value.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 a detection signal of the rotational speed of the motor 20 output from the rotation sensor 201. I / F504 receives a detection signal of the output torque of the motor 20 output from the torque sensor 202. I / F504 receives a detection signal of the brake pedal depression amount output from sensor 71. I / F504 receives a detection signal of the accelerator pedal depression amount (acceleration command value) output from sensor 81. I / F504 receives a gear shift instruction signal output from gear shift indicator 90.

[0035] [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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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 an ASIC or programmable hardware.

[0047] [1-3. Functions of the control device] Returning to Figure 1, the functions of the control device 50 will be explained. The following functions are realized when the processor 501 executes the motor control program 510.

[0048] When the processor 501 receives a command to switch from a series connection state to a parallel connection state, it determines whether the torque difference, which is the difference between the output torque of the motor 20 in the series connection state and the output torque of the motor 20 in the parallel connection state, exceeds a threshold.

[0049] Let me explain in detail. The processor 501 acquires the output torque of the motor 20 detected by the torque sensor 202 when the connection state of the multiple windings 21u, 22u, 21v, 22v, 21w, and 22w (hereinafter also referred to as "winding connection state") is in a series connection state. 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 is 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 processor 501 determines whether the torque difference, which is the difference between the measured torque when the winding connection state is in a series connection state and the estimated torque when the winding connection state is in a parallel connection state, exceeds a threshold value. However, the threshold value is a positive value.

[0050] The same applies when switching the winding connection state from a parallel connection state to a series connection state. That is, the processor 501 acquires the measured torque when the winding connection state is a parallel connection state. The processor 501 determines whether the torque difference, which is the difference between the measured torque when the winding connection state is a parallel connection state (torque before switching the winding connection state) and the estimated torque when the winding connection state is a series connection state (torque after switching the winding connection state), exceeds a threshold.

[0051] The output torque of motor 20 is determined by the winding connection state, the rotational speed of motor 20, and the acceleration command value. Figure 4 is a graph showing an example of the characteristics of a motor according to the first embodiment. In Figure 4, the left graph shows the rotational speed-torque characteristics (NT characteristics) of the motor. In the left graph, the vertical axis represents torque and the horizontal axis represents rotational speed. The center and right graphs each show the acceleration command value-torque characteristics of the motor. In the center and right graphs, the vertical axis represents torque and the horizontal axis represents the acceleration command value.

[0052] From the N-T characteristics, it can be generally seen that the series connection state is a winding connection state capable of outputting high torque in a region where the rotation speed of the motor 20 is low, and the parallel connection state is a winding connection state capable of outputting low torque in a region where the rotation speed of the motor 20 is high. That is, the series connection state is a low-rotation high-torque type winding connection state, and the parallel connection state is a high-rotation low-torque type winding connection state.

[0053] Switching the winding connection state from the series connection state to the parallel connection state corresponds to an upshift in a mechanical transmission, and switching the winding connection state from the parallel connection state to the series connection state corresponds to a downshift in a mechanical transmission. Switching the winding connection state from the series connection state to the parallel connection state, and switching the winding connection state from the parallel connection state to the series connection state is also referred to as "electrical gear change".

[0054] In the example of the N-T characteristics in FIG. 4, the solid line graph indicates the maximum torque in the series connection state, that is, the output torque of the motor when the acceleration command value input to the control device 50 is 100%. Similarly, the broken line graph indicates the maximum torque in the parallel connection state.

[0055] In the rotation speed range from 0 to R1 in the series connection state, the maximum torque T1 is generated. In the series connection state, when the rotation speed exceeds R1, the maximum torque gradually decreases from T1, and the maximum torque becomes 0 at the rotation speed R2. In the parallel connection state, in the rotation speed range from 0 to R3 (>R1), the maximum torque T2 (<T1) is generated. In the parallel connection state, when the rotation speed exceeds R3, the maximum torque gradually decreases from T2, and the maximum torque becomes 0 at the rotation speed R4. In the rotation speed range from 0 to Rx, the maximum torque in the series connection state is larger than the maximum torque in the parallel connection state. The maximum torques in the series connection state and the parallel connection state are the same at the rotation speed Rx, and in the rotation speed range larger than Rx, the maximum torque in the series connection state is smaller than the maximum torque in the parallel connection state.

[0056] The central graph shows acceleration command value-torque characteristics at the rotation speed Ra (0<Ra<R1). As described above, the solid line graph on the left shows N-T characteristics when the acceleration command value is 100%. When the acceleration command value changes at the same motor rotation speed, the amount of electric power supplied to the motor 20 changes in accordance with the acceleration command value, thereby changing the output torque. In the example of FIG. 4, the relationship between the acceleration command value and the torque is a proportional relationship. That is, in the series connection state, at the rotation speed Ra, the torque changes linearly with respect to the acceleration command value within a range from 0 to T1. In the parallel connection state, at the rotation speed Ra, the torque changes linearly with respect to the acceleration command value within a range from 0 to T2.

[0057] The graph on the right shows acceleration command value-torque characteristics at the rotation speed Rb (Rx<Rb<R3). In the series connection state, at the rotation speed Rb, the torque changes linearly with respect to the acceleration command value within a range from 0 to T3 (<T2). In the parallel connection state, at the rotation speed Rb, the torque changes linearly with respect to the acceleration command value within a range from 0 to T2.

[0058] When the winding connection state is the series connection state, the rotation speed of the motor 20 is Ra, and the acceleration command value is 100%, the output torque of the motor 20 is T1. In this state, when the winding connection state is switched from the series connection state to the parallel connection state, the output torque of the motor 20 changes to T2. The torque difference, which is the difference between the torque T1 and the torque T2, is large, and a large torque fluctuation (torque drop) occurs along with the switching of the winding connection state.

[0059] On the other hand, when the winding connection state is the parallel connection state, the rotation speed of the motor 20 is Rb, and the acceleration command value is 100%, the output torque of the motor 20 is T2. In this state, when the winding connection state is switched from the parallel connection state to the series connection state, the output torque of the motor 20 changes to T3. The torque difference T2-T3 is small, and the torque fluctuation accompanying the switching of the winding connection state is small.

[0060] The processor 501 determines whether the torque difference before and after the winding connection state switching (before and after the gear change) exceeds a threshold. While the torque difference exceeds the threshold, the processor 501 prohibits the winding switching device 100 from switching from the series connection state to the parallel connection state. This prevents large torque fluctuations associated with the winding connection state switching and reduces the discomfort felt by the driver.

[0061] The term "torque difference" here refers to the absolute value of the difference between the torque in the winding connection state before switching and the torque in the winding connection state after switching. When the torque in the winding connection state after switching is greater than the torque in the winding connection state before switching, and the torque difference exceeds a threshold, the torque will increase sharply before and after switching the winding connection state. In this case, switching the winding connection state is prohibited.

[0062] Furthermore, after the processor 501 transitions from a first torque state where the torque difference exceeds a threshold to a second torque state where the torque difference falls below the threshold, it causes the winding switching device 100 to perform a winding connection state switch.

[0063] Let me explain in detail. Figure 5 is a diagram showing the range in which winding switching is permitted in the motor according to the first embodiment. In Figure 5, the area indicated by the shaded area is the range in which switching of the winding connection state is permitted (hereinafter also referred to as the "switching permitted range"). That is, the switching permitted range is the range of torque, rotational speed, and acceleration command value in which the torque difference before and after switching of the winding connection state is below a threshold.

[0064] The torque state referred to here is the motor control state determined by torque, rotational speed, and acceleration command value. Specifically, the first torque state is the motor control state that falls within the range of torque, rotational speed, and acceleration command value (outside the shaded area in Figure 5) when the torque difference before and after switching the winding connection state exceeds a threshold. The second torque state is the motor control state that falls within the range of torque, rotational speed, and acceleration command value (the shaded area in Figure 5) when the torque difference before and after switching the winding connection state is below the threshold. The shaded area in Figure 5 indicates the switching permission range.

[0065] If the torque difference exceeds a threshold, the processor 501 waits to switch the winding connection state until it transitions from the first torque state to the second torque state. When the torque difference falls below the threshold, that is, when it transitions from the first torque state to the second torque state, the processor 501 causes the winding switching device 100 to perform the winding state switch.

[0066] In the example shown in Figure 5, when the winding connection state is series, the rotational speed is Ra, and the acceleration command value is 100%, the output torque of the motor 20 is T1. If a speed change instruction is input to the control device 50, the output torque of the motor 20 after switching the winding connection state from series to parallel is T2, and the torque difference is T1-T2. Since the torque difference T1-T2 exceeds the threshold Th (first torque state), the switching of the winding connection state is prohibited.

[0067] If the acceleration command value decreases while the rotational speed of motor 20 is maintained at Ra, the torque difference decreases linearly, as shown in the central graph of Figure 5. When the acceleration command value reaches A1, the torque difference reaches the threshold Th, and the system transitions from the first torque state to the second torque state. At this time, the prohibition on switching the winding connection state is released, and the switching of the winding connection state is performed.

[0068] On the other hand, when the winding connection state is parallel, the rotational speed is Rb, and the acceleration command value is 100%, the output torque of the motor 20 is T2. If a speed change instruction is input to the control device 50 at this point, the output torque of the motor 20 after switching the winding connection state from parallel to series is T3, and the torque difference is T2-T3. Since the torque difference T2-T3 is less than or equal to the threshold Th (second torque state), the winding connection state is switched.

[0069] For example, the non-volatile memory 102 may store a characteristic map showing the correspondence between torque, rotational speed, and acceleration command value. The characteristic map is an example of "correspondence information." The characteristic map is information showing the NT characteristics and acceleration command value-torque characteristics as described above. The switching permission range is mapped to the characteristic map. The processor 501 may refer to the characteristic map to determine whether the torque difference exceeds a threshold, that is, whether the control state of the motor 20 is the first torque state. Specifically, the processor 501 acquires the measured torque, input acceleration command value, and rotational speed in the winding connection state before switching, and determines whether the position (torque state) on the characteristic map determined by the acquired measured torque, acceleration command value, and rotational speed is included in the switching permission range.

[0070] The processor 501 continuously acquires measured torque, acceleration command value, and rotational speed values ​​sequentially and updates the position of the torque state on the characteristic map. The processor 501 prohibits switching the winding connection state while the torque state is not within the switching permission range, and when the torque state transitions from outside the switching permission range to within the switching permission range, it causes the winding switching device 100 to switch the winding connection state.

[0071] However, since torque and acceleration command value are proportional, if the torque is determined, the acceleration command value can be determined, and if the acceleration command value is determined, the torque can be determined. Therefore, the processor 501 may identify the torque state by at least one of the torque and acceleration command value and the rotational speed. For example, the characteristic map may be information showing the correspondence between at least one of the torque and acceleration command value and the rotational speed.

[0072] It is also possible to determine whether the torque difference exceeds a threshold without using a characteristic map. The processor 501 acquires the measured torque before the winding connection state is switched, and estimates the output torque of the motor 20 after the winding connection state is switched from the acceleration command value and the rotational speed of the motor 20 at that time. The processor 501 can calculate the torque difference from the measured torque and the estimated torque, and compare the calculated torque difference with a threshold.

[0073] The winding connection status switching instruction is a gear shift instruction output from the gear shift indicator 90. In vehicles equipped with the 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.

[0074] 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 of depression of the brake pedal 70 (braking command value), and the amount of depression of the accelerator pedal 80 (acceleration command value). That is, an automatic transmission 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 of depression of the brake pedal 70 (braking command value), and the amount of depression of the accelerator pedal 80 (acceleration command value), and the generated gear shift command is input to the control device 50.

[0075] If the torque difference continues to exceed a threshold, the electrical gear change will not be performed for a long time. For this reason, the control device 50 may be equipped with a timer (not shown) and may have a timeout period for prohibiting electrical gear changes. That is, the control device 50 may start timing after a gear change instruction is input, and if it has not output an instruction to switch the winding connection state after a certain period (timeout period) has elapsed, it may cancel the gear change instruction due to the timeout. This can reduce the discomfort to the driver caused by the gear change shock of the electrical gear change. As another example, the control device 50 may perform an electrical gear change if the prohibition period for electrical gear changes has timed out.

[0076] [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 the following switching control process by having the processor 501 execute the motor control program 510.

[0077] Figure 6 is a flowchart showing an example of switching control processing by the control device according to the first embodiment.

[0078] When the driver wants to change the vehicle's electrical gears, they operate the gear shift indicator 90 to input an instruction to the vehicle for an electrical gear change, 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 accepts the instruction to switch the winding connection state (step S101).

[0079] 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).

[0080] The processor 501 determines whether the torque difference before and after the winding connection state switching exceeds a threshold (step S103). Specifically, the processor 501 identifies the position of the torque state on the characteristic map from the torque, rotational speed, and acceleration command value acquired in step S102, and determines whether the torque state is outside the switching permission range. In another example, the processor 501 estimates the output torque of the motor 20 after the winding connection state switching based on the rotational speed and acceleration command value acquired in step S102, and compares the torque difference calculated from the measured torque and the estimated torque with a threshold.

[0081] If the torque difference exceeds a threshold (YES in step S103), the processor 501 returns to step S02 without outputting an instruction to switch the winding connection state. This prevents the switching of the winding connection state.

[0082] If the torque difference is below a threshold (NO in step S103), the processor 501 outputs a winding connection state switching instruction to the winding switching device 100 (step S104). This switches the connection states of windings 21u, 22u, 21v, 22v, 21w, and 22w, and an electrical gear change is performed. This completes the switching control process.

[0083] [2. Second Embodiment] Since the configuration of the winding switching system according to the second 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.

[0084] [2-1. Functions of the control device] In the second embodiment, the control device 50 causes the winding switching device 100 to switch from a series connection state to a parallel connection state based on a specific timing at which the magnitude of the output torque before switching the winding connection state and the magnitude of the output torque after switching the winding connection state are reversed, when the rotational speed of the motor 20 increases over time and the output torque of the motor 20 decreases over time in the parallel connection state.

[0085] Figure 7 is a diagram illustrating the switching of the winding connection state of the motor according to the second embodiment.

[0086] For example, when the windings of motor 20 are connected in series, if an acceleration command value of 100% is input, the torque and rotational speed will change in the direction indicated by the arrows in Figure 7. In other words, the output torque of motor 20 is T1 until the rotational speed reaches R1 from 0, and once the rotational speed exceeds R1, the output torque gradually decreases from T1. Even if a speed change instruction (winding connection state switching instruction) is input to the control device 50, the processor 501 prohibits the switching of the winding connection state until a specific timing when the rotational speed reaches Rx. Hereinafter, the rotational speed Rx will also be referred to as the "specific rotational speed".

[0087] When a specific timing is reached (i.e., when the rotational speed reaches a specific rotational speed Rx), the processor 501 releases the restriction on the winding connection state and outputs a winding connection state switching instruction to the winding switching device 100. As a result, the winding connection state switches from a series connection state to a parallel connection state.

[0088] By switching the winding connection state from series to parallel at a specific timing, the output torque of the motor 20 changes smoothly. That is, the torque gradually decreases from T1, and after reaching T2, it remains at T2. In this way, torque fluctuations associated with the switching of the winding connection state are suppressed.

[0089] The winding connection state switching control according to the second embodiment described above (hereinafter also referred to as "specific switching control") does not have to be executed only when the acceleration command value is 100%. For example, the processor 501 may execute the specific switching control when the acceleration command value is greater than or equal to a specific value. If the acceleration command value is less than the specific value, the processor 501 may execute the winding connection state switching control process described in the first embodiment.

[0090] [2-2. Operation of the winding switching system] Figure 8 is a flowchart showing an example of a switching control process by the control device according to the second embodiment.

[0091] When the driver wants to change the vehicle's electrical gears, 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 accepts the instruction to switch the winding connection state (step S201).

[0092] 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 S202).

[0093] The processor 501 determines whether the current winding connection state is a low-speed, high-torque type winding connection state, that is, a series connection state (step S203).

[0094] If the current winding connection state is not a low-speed, high-torque type winding connection state (i.e., it is a parallel connection state) (NO in step S203), the processor 501 determines whether the torque difference before and after switching the winding connection state exceeds a threshold (step S204). Specifically, the processor 501 identifies the position of the torque state on the characteristic map from the torque, rotational speed, and acceleration command value acquired in step S202, and determines whether the torque state is outside the switching permission range. In another example, the processor 501 estimates the output torque of the motor 20 after switching the winding connection state based on the rotational speed and acceleration command value acquired in step S102, and compares the torque difference calculated from the measured torque and the estimated torque with a threshold.

[0095] If the torque difference exceeds a threshold (YES in step S204), the processor 501 returns to step S02 without outputting an instruction to switch the winding connection state. This prevents the switching of the winding connection state.

[0096] If the torque difference is below a threshold (NO in step S204), the processor 501 outputs a winding connection state switching instruction to the winding switching device 100 (step S205). This switches the connection states of windings 21u, 22u, 21v, 22v, 21w, and 22w, and an electrical gear change is performed. The output of the winding connection state switching instruction terminates the switching control process.

[0097] In step S203, if the current winding connection state is a low-speed, high-torque type winding connection state (i.e., a series connection state) (YES in step S203), the processor 501 determines whether the currently input acceleration command value is greater than or equal to a specific value (step S206).

[0098] If the currently input acceleration command value is less than a specific value (NO in step S206), the processor 501 proceeds to step S204.

[0099] If the currently input acceleration command value is greater than or equal to a specific value (YES in step S206), the processor 501 determines whether or not the rotational speed of the motor 20 has reached a specific rotational speed Rx (step S207).

[0100] If the rotational speed of the motor 20 has not reached a specific rotational speed Rx (NO in step S207), the processor 501 returns to step S02 without outputting an instruction to switch the winding connection state. This prevents the switching of the winding connection state.

[0101] When the rotational speed of the motor 20 reaches a specific rotational speed Rx (YES in step S207), the processor 501 outputs a winding connection state switching instruction to the winding switching device 100 (step S205). This switches the connection state of windings 21u, 22u, 21v, 22v, 21w, and 22w, and an electrical gear change is performed. The output of the winding connection state switching instruction terminates the switching control process.

[0102] [3. Third Embodiment] The winding switching device according to the third 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.

[0103] Figure 9 is a circuit diagram showing an example of the configuration of a winding switching device according to the third 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.

[0104] 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.

[0105] 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 a low-speed, high-torque type connection state, while the partially connected state is a high-speed, low-torque type connection state.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] The other components of the winding switching device 100A according to the third 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.

[0113] In the third 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.

[0114] [4. Variant] In the third 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.

[0115] [5. 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 all modifications within the meaning and scope of the equivalents of the claims. [Explanation of symbols]

[0116] 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 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 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, Equipped with, The control device is Including the processor, The aforementioned processor, When a switching instruction from the first connection state to the second connection state is received, the step of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, The steps include: prohibiting the winding switching device from switching from the first connection state to the second connection state while the torque difference exceeds the threshold; Perform an action that includes A winding switching system for vehicle motors.

2. The operation further includes the step of causing the winding switching device to switch from the first connection state to the second connection state after transitioning from a first torque state in which the torque difference exceeds the threshold to a second torque state in which the torque difference is less than or equal to the threshold, A winding switching system for a vehicle motor according to claim 1.

3. The determination step includes determining whether the torque difference exceeds the threshold based on the acceleration command of the vehicle or the output torque of the drive motor and the rotational speed of the drive motor. A winding switching system for a vehicle motor according to claim 1.

4. The determination step includes determining whether the torque difference exceeds the threshold by determining whether the measured value of the vehicle's acceleration command and the measured value of the drive motor's output torque and the measured value of the drive motor's rotational speed are included in the switchable range defined in the correspondence information indicating the correspondence between the vehicle's acceleration command and the output torque of the drive motor and the rotational speed of the drive motor. A winding switching system for a vehicle motor according to claim 1.

5. The operation further includes the step of causing the winding switching device to switch from the first connection state to the second connection state based on a specific timing at which the magnitude of the first output torque and the magnitude of the second output torque reverse when the rotational speed of the drive motor increases over time and the first output torque decreases over time in the first connection state. A winding switching system for a vehicle motor according to any one of claims 1 to 4.

6. A control device for controlling a drive motor that drives the wheels of a vehicle, Equipped with a processor, The aforementioned processor, When an instruction is received to switch the connection state of the multiple windings in the drive motor from a first connection state to a second connection state, the step of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, The steps include: prohibiting switching from the first connection state to the second connection state while the torque difference exceeds the threshold; Perform an action that includes Control device.

7. 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, When an instruction is received to switch the connection state of the multiple windings in the drive motor from a first connection state to a second connection state, the step of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, The steps include: prohibiting switching from the first connection state to the second connection state while the torque difference exceeds the threshold; including, A method for controlling a vehicle motor.

8. A computer program used in a control device that controls the drive motors that drive the wheels of a vehicle, On the computer, When an instruction is received to switch the connection state of the multiple windings in the drive motor from a first connection state to a second connection state, the step of determining whether the torque difference, which is the difference between the first output torque of the drive motor in the first connection state and the second output torque of the drive motor in the second connection state, exceeds a threshold, The steps include: prohibiting switching from the first connection state to the second connection state while the torque difference exceeds the threshold; To execute Computer program.

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