Motor control device

Abstract

The purpose of the present invention is to suppress a decrease in reliability of each motor for independently driving each wheel of a vehicle. A motor control device (3) is a device for controlling each motor (2) that independently drives each wheel (1) of a vehicle (10). A motor control device (3) is provided with: a control information transmission / reception unit (31) that receives control information (41) from a host control device (4), the control information (41) including a torque command (412) to a motor (2) and driving state information (411) relating to the driving state of a vehicle (10); a motor state acquisition unit (32) that acquires motor state information (321) relating to the state of the motor (2); and a torque command switching unit (33) that, on the basis of the control information (41) received from the higher-level control device (4) and the motor state information (321) acquired by the motor state acquisition unit (32), switches whether to control the motor (2) in accordance with the torque command (412) or to control the motor (2) in accordance with a corrected torque command (371) obtained by correcting the torque command (412).

Description

Technical Field

[0001] The present invention relates to a motor control device. Background Art

[0002] In recent years, with the growing demand for energy conservation, motor control devices that control electric motors such as AC motors have been adopted in a wide range of applications, including automobiles, home appliances, infrastructure, and industrial equipment. In particular, in electric vehicles, research is underway to create in-wheel motors (in-wheel motors) that incorporate electric motors within each wheel to expand interior space and battery installation space.

[0003] With in-wheel motors, there's a strong demand for miniaturization and higher output density, making temperature management crucial. Vehicles equipped with in-wheel motors can independently drive each wheel. Specifically, they can independently adjust the torque of each wheel to improve driving performance and safety, adapting to road conditions such as those on poor roads. For example, if a vehicle equipped with in-wheel motors encounters water and a wheel is about to slip, the torque of that wheel can be adjusted to prevent slippage. In this way, vehicles equipped with in-wheel motors can improve driving performance and safety by independently controlling the in-wheel motors installed in each wheel.

[0004] On the other hand, vehicles equipped with in-wheel motors can independently drive each wheel. This leads to a greater difference in the operating rates of the motors driving each wheel, and the status of each motor (e.g., motor temperature, magnetic flux, or degree of degradation) tends to vary widely. Consequently, in vehicles equipped with in-wheel motors, the reliability of motors with high operating rates tends to decrease.

[0005] As a technology for coping with such a reduction in motor reliability, for example, Patent Document 1 is known. Patent Document 1 discloses a technology for allocating a larger torque command to a motor disposed upstream of a coolant circulation path for cooling the motor.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-88768 Summary of the Invention

[0009] However, Patent Document 1 merely discloses a technique for distributing torque commands based on the coolant circulation path and the motor's layout. It does not disclose any countermeasures for situations where motor reliability decreases due to the vehicle's driving conditions or the motor's own state. Therefore, the technique disclosed in Patent Document 1 leaves room for improvement in suppressing motor reliability degradation.

[0010] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to suppress a decrease in the reliability of each electric motor that independently drives each wheel of a vehicle.

[0011] In order to solve the above-mentioned problems, the motor control device of the present invention controls each motor of each wheel of an independent driving vehicle, and the motor control device is characterized in that it includes: a control information transceiver, which receives control information from a host control device, and the control information includes a torque instruction to the motor and driving status information related to the driving status of the vehicle; a motor status acquisition unit, which acquires motor status information related to the status of the motor; and a torque instruction switching unit, which switches whether to control the motor according to the torque instruction or to control the motor according to a corrected torque instruction obtained by correcting the torque instruction based on the control information received from the host control device and the motor status information acquired by the motor status acquisition unit.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to suppress a decrease in the reliability of each electric motor that independently drives each wheel of a vehicle.

[0014] Other problems, structures, and effects than those described above will become apparent from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A diagram illustrating a vehicle including a motor control device.

[0016] Figure 2 It shows Figure 1 The diagram shows the configuration of the motor control device.

[0017] Figure 3 It shows Figure 2 The diagram shows the configuration of the torque command switching unit.

[0018] Figure 4 It shows Figure 3 Flowchart of the processing of the torque instruction selection unit shown.

[0019] Figure 5 It is an explanation Figure 3 FIG. 2 is a diagram showing another example of the motor state determination unit and the correction torque instruction calculation unit. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. It should be noted that, unless otherwise specified, configurations or functions denoted by the same reference numerals in each embodiment have the same configurations or functions in each embodiment, and their description will be omitted.

[0021] Figure 1 3A and 3B are diagrams illustrating a vehicle 10 including motor control devices 3a to 3d.

[0022] Vehicle 10 is equipped with electric motors 2a-2d that independently drive wheels 1a-1d. Vehicle 10 may also be an electric vehicle powered by a battery (not shown). Each electric motor 2a-2d is provided corresponding to each wheel 1a-1d. Each electric motor 2a-2d may also be an in-wheel motor installed within each wheel 1a-1d. Each electric motor 2a-2d may also be an AC motor equipped with permanent magnets.

[0023] The operation of each motor 2a-2d is controlled by a motor control device 3a-3d. Each motor control device 3a-3d is provided corresponding to each motor 2a-2d. Each motor control device 3a-3d may also be a local ECU that controls each motor 2a-2d. Each motor control device 3a-3d controls each motor 2a-2d based on control information 41 from the host control device 4.

[0024] The host control device 4 may be a central ECU that centrally controls the driving of the vehicle 10. The host control device 4 calculates torque commands 412 to be given to the motors 2a to 2d and transmits control information 41 including the calculated torque commands 412 to the motor control devices 3a to 3d via the vehicle network of the vehicle 10.

[0025] In this embodiment, the wheels 1a to 1d are also collectively referred to as “wheels 1 .” The motors 2a to 2d are also collectively referred to as “motor 2 .” The motor control devices 3a to 3d are also collectively referred to as “motor control devices 3 .”

[0026] The vehicle 10 can improve driving performance and driving safety by adjusting the torque command 412 included in the control information 41 from the host control device 4 according to road conditions, etc. For example, when the vehicle 10 is traveling on a downhill road with many curves, it is considered to control the front wheel motors 2 (e.g., motors 2a and 2c) to perform regenerative braking operations more frequently. In this case, the operating rate of the front wheel motors 2 increases, and the reliability of the front wheel motors 2 is likely to be reduced. For example, if only the right wheel 1 (e.g., wheels 1a and 1b) enters water, it is considered to control the torque command 412 of the right motors 2 (e.g., motors 2a and 2b) to suppress slippage of the right wheel 1, thereby suppressing sudden changes in the rotation speed of the right motor 2. In this case, the operating rate of the left motors 2 (e.g., motors 2c and 2d) increases, and the reliability of the left motors 2 is likely to be reduced. As described above, due to differences in road conditions and the like, the torque commands 412 and rotational speeds of the respective motors 2 vary, and an increase in the operating rate of a specific motor 2 and a corresponding decrease in reliability pose a problem.

[0027] Therefore, in the present embodiment, a motor control device 3 is provided that can improve the driving capability and driving safety of the vehicle 10 while suppressing a decrease in the reliability of each motor 2 .

[0028] Figure 2 It shows Figure 1 FIG. 2 is a diagram showing the configuration of the motor control device 3. Figure 3 It shows Figure 2 FIG. 2 is a diagram showing the configuration of the torque command switching unit 33.

[0029] The motor control device 3 includes a control information transceiver 31 , a motor state acquisition unit 32 , and a torque command switching unit 33 .

[0030] The control information transceiver 31 transmits and receives control information 41 related to the control of the electric motor 2 between the host control device 4 and the host control device 4. Examples of information included in the control information 41 transmitted from the host control device 4 to the motor control device 3 include, in addition to a torque command 412 for the electric motor 2, driving state information 411 related to the driving state of the vehicle 10. The control information transceiver 31 receives the control information 41 including the torque command 412 and the driving state information 411 from the host control device 4.

[0031] The torque command 412 included in the control information 41 received from the host control device 4 is a torque command given to the motor 2 being controlled by the motor control device 3. The driving state information 411 included in this control information 41 reflects the driving state of the vehicle 10, which changes depending on driving conditions such as road conditions. This driving state information 411 includes at least one of the following: the torque command 412 for another motor 2 installed in the vehicle 10, the rotational speed of the other motor 2, and the steering angle of another wheel 1 driven by the other motor 2. The rotational speed of the motor 2 being controlled and the steering angle of the wheel 1 driven by the other motor 2 can be transmitted to the motor control device 3 from a sensor that detects these quantities, or they can be transmitted to the host control device 4 without passing through the motor control device 3. When transmitted to the host control device 4, this driving state information 411 includes at least one of the rotational speed of the motor 2 being controlled and the steering angle of the wheel 1 driven by the motor 2 being controlled.

[0032] The motor state acquisition unit 32 acquires motor state information 321 related to the state of the motor 2 being controlled. The motor state information 321 includes at least one of the following: the temperature of the motor 2, the magnetic flux of the magnets constituting the motor 2, the demagnetization rate of the magnets, and the degree of deterioration of the coils constituting the motor 2. The motor state acquisition unit 32 can acquire the temperature of the motor 2 from a temperature sensor attached to the motor 2. The motor state acquisition unit 32 can calculate the magnetic flux of the magnets based on the voltage of the coils of the motor 2. The motor state acquisition unit 32 can calculate the demagnetization rate based on the calculated magnetic flux. The demagnetization rate is the rate at which the magnets are irreversibly demagnetized by magnetic force. The motor state acquisition unit 32 can calculate the degree of deterioration of the coils based on the current flowing through the coils of the motor 2. The degree of deterioration of the coils indicates the degree of deterioration in the insulation performance of the coils due to, for example, deterioration of the insulator covering the coils.

[0033] The torque instruction switching unit 33 switches whether to control the motor 2 corresponding to the torque instruction 412 to the control object motor 2 or to control the motor 2 corresponding to the corrected torque instruction 371 obtained by correcting the torque instruction 412 based on the control information 41 received from the upper control device 4 and the motor status information 321 obtained by the motor status acquisition unit 32.

[0034] Specifically, if Figure 3 As shown, the torque command switching unit 33 includes a driving state determination unit 34 , a motor state determination unit 36 ​​, a correction torque command calculation unit 37 , and a torque command selection unit 35 .

[0035] The driving state determination unit 34 determines whether the driving state of the vehicle 10 is stable based on the driving state information 411 included in the control information 41 received from the host control device 4. A stable state is a state in which the driving of the vehicle 10 is stable, changing according to driving conditions such as road conditions. A stable driving state of the vehicle 10 is a state in which changes in the speed and steering angle of the vehicle 10 are small, such as when the vehicle 10 is cruising.

[0036] The driving state determination unit 34 of this embodiment calculates a difference between the controlled motor 2 and the other motors 2 with respect to at least one piece of information included in the driving state information 411 (the torque command 412, the rotational speed of the motor 2, and the steering angle of the wheel 1). If the calculated difference is less than a predetermined threshold, the driving state determination unit 34 determines that the driving state of the vehicle 10 is stable. If the calculated difference is greater than the threshold, the driving state determination unit 34 determines that the driving state of the vehicle 10 is not stable (an unstable state). The driving state determination unit 34 then outputs the determination result 341 of the driving state determination unit 34 to the torque command selection unit 35.

[0037] The motor state determination unit 36 ​​determines whether the state of the motor 2 to be controlled is a high operating state based on the motor state information 321 acquired by the motor state acquisition unit 32. The high operating state is a state in which the operating rate of the motor 2 is high.

[0038] The motor state determination unit 36 ​​of this embodiment determines whether at least one piece of information included in the motor state information 321 (the temperature of the motor 2, the magnetic flux of the magnet, the demagnetization ratio of the magnet, and the degree of deterioration of the coil) exceeds a predetermined allowable value. If at least one piece of information included in the motor state information 321 exceeds the allowable value, the motor state determination unit 36 ​​determines that the state of the controlled motor 2 is in the high-speed operation state. If at least one piece of information included in the motor state information 321 does not exceed the allowable value, the motor state determination unit 36 ​​determines that the state of the controlled motor 2 is not in the high-speed operation state (normal operation state). The motor state determination unit 36 ​​then outputs the determination result 361 of the motor state determination unit 36 ​​to the modified torque command calculation unit 37 and the torque command selection unit 35.

[0039] For example, if the temperature of the motor 2 acquired by the motor state acquisition unit 32 is higher than the allowable value, the motor state determination unit 36 ​​determines that the state of the controlled motor 2 is in the high operating state. For example, if the magnetic flux of the magnet acquired by the motor state acquisition unit 32 is lower than the allowable value, the motor state determination unit 36 ​​determines that the state of the controlled motor 2 is in the high operating state. For example, if the demagnetization ratio acquired by the motor state acquisition unit 32 is higher than the allowable value, the motor state determination unit 36 ​​determines that the state of the controlled motor 2 is in the high operating state. For example, if the degree of deterioration of the coil acquired by the motor state acquisition unit 32 is higher than the allowable value, the motor state determination unit 36 ​​determines that the state of the controlled motor 2 is in the high operating state.

[0040] The corrected torque command calculation unit 37 calculates a corrected torque command 371 by correcting the torque command 412 received from the host control device 4 based on the determination result 361 of the motor state determination unit 36. Specifically, when the corrected torque command calculation unit 37 determines that the state of the controlled motor 2 is the high operating state, the corrected torque command 371 is calculated to be smaller than the value of the torque command 412 received from the host control device 4. The corrected torque command calculation unit 37 outputs the calculated corrected torque command 371 to the torque command selection unit 35.

[0041] The value of the corrected torque instruction 371 can be any value less than the value of the torque instruction 412, and is not particularly limited. For example, the corrected torque instruction calculation unit 37 may calculate a value obtained by multiplying the difference in motor state information 321 (temperature, magnetic flux, etc.) between the motor 2 being controlled and the other motor 2 by a predetermined gain as a correction value, and subtract the calculated correction value from the torque instruction 412 to calculate the corrected torque instruction 371. The motor state information 321 of the other motor 2 is transmitted from the upper control device 4 and received by the control information transceiver 31. In addition, for example, the corrected torque instruction calculation unit 37 may calculate the corrected torque instruction 371 by multiplying the torque instruction 412 received from the upper control device 4 by a coefficient greater than 0 and less than 1. Although this is an extreme example, the corrected torque instruction calculation unit 37 may also set the corrected torque instruction 371 to 0.

[0042] The torque command selection unit 35 selects a torque command to be given to the electric motor 2 to be controlled based on at least one of the determination result 341 of the driving state determination unit 34 and the determination result 361 of the electric motor state determination unit 36 ​​.

[0043] Specifically, when the torque command selection unit 35 determines that the driving state of the vehicle 10 is stable, it outputs a corrected torque command 371 that is corrected to a value smaller than the torque command 412, and controls the electric motor 2 to be controlled based on the corrected torque command 371. On the other hand, when the torque command selection unit 35 determines that the driving state of the vehicle 10 is not stable, it outputs the torque command 412, and controls the electric motor 2 to be controlled based on the torque command 412.

[0044] When the state of the motor 2 to be controlled is determined to be in the high operating state, the torque command selection unit 35 outputs a corrected torque command 371 corrected to a value smaller than the torque command 412, thereby controlling the motor 2 to be controlled according to the corrected torque command 371. On the other hand, when the state of the motor 2 to be controlled is determined not to be in the high operating state, the torque command selection unit 35 outputs the torque command 412, thereby controlling the motor 2 to be controlled.

[0045] In addition, the torque instruction selection unit 35 can select the torque instruction given to the motor 2 of the control object based on the judgment result 341 of the driving state judgment unit 34 and the judgment result 361 of the motor state judgment unit 36. In this case, it is preferable that the torque instruction selection unit 35 selects the torque instruction given to the motor 2 of the control object based on the judgment result 341 of the driving state judgment unit 34 and the judgment result 361 of the motor state judgment unit 36. Figure 4 The torque command to be given to the electric motor 2 to be controlled is selected through the processing shown.

[0046] Figure 4 It shows Figure 3 Flowchart of the processing of the torque instruction selection unit 35 shown.

[0047] In step S1, the torque command selection unit 35 checks the determination result 341 of the driving state determination unit 34 and determines whether the driving state of the vehicle 10 is determined to be stable. If the driving state of the vehicle 10 is determined to be stable (step S1: Yes), the torque command selection unit 35 proceeds to step S2. If the driving state of the vehicle 10 is determined to be not stable (step S1: No), the torque command selection unit 35 proceeds to step S3.

[0048] In step S2, the torque command selection unit 35 checks the determination result 361 of the motor state determination unit 36 ​​to determine whether the state of the motor 2 to be controlled is determined to be in the high-speed operation state. If the state of the motor 2 to be controlled is determined to be in the high-speed operation state (step S2: Yes), the torque command selection unit 35 proceeds to step S4. If the state of the motor 2 to be controlled is determined not to be in the high-speed operation state (step S2: No), the torque command selection unit 35 proceeds to step S3.

[0049] In step S3, the torque command selection unit 35 selects the torque command 412 received from the host control device 4 as the torque command to be given to the controlled motor 2. In other words, the motor control device 3 does not correct the torque command 412. The torque command selection unit 35 then proceeds to step S5.

[0050] In step S4 , the torque command selection unit 35 selects the correction torque command 371 calculated by the correction torque command calculation unit 37 as the torque command to be given to the controlled motor 2 .

[0051] In step S5, the torque command selection unit 35 outputs the selected torque command 412 or the modified torque command 371 to the drive circuit of the motor 2 to be controlled. Figure 4 The processing shown.

[0052] like Figure 4 As shown, the torque command selection unit 35 selects a torque command to be given to the controlled motor 2 by giving priority to the determination result 341 of whether the driving state of the vehicle 10 is stable over the determination result 361 of whether the state of the motor 2 is high operating state.

[0053] Specifically, when the driving state of the vehicle 10 is determined to be stable and the state of the controlled electric motor 2 is determined to be in the high-speed operation state, the torque command selection unit 35 outputs a corrected torque command 371 corrected to a value smaller than the torque command 412, and controls the controlled electric motor 2 according to the corrected torque command 371. On the other hand, when the driving state is determined to be not stable, the torque command selection unit 35 outputs the torque command 412 regardless of whether the state of the controlled electric motor 2 is in the high-speed operation state, and controls the controlled electric motor 2 according to the torque command 412.

[0054] When the driving state of the vehicle 10 is not stable, the host control device 4 adjusts the torque command 412 according to the driving state such as the road condition to ensure the driving ability and driving safety of the vehicle 10 and sends it to the motor control device 3. Figure 4 The torque command selection unit 35 in the illustrated process can select and apply the modified torque command 371 to the controlled electric motor 2 only when the driving state of the vehicle 10 is stable. Therefore, the motor control device 3 can suppress the reduction in the reliability of the electric motor 2 without sacrificing the driving performance and driving safety of the vehicle 10.

[0055] As described above, the motor control device 3 of this embodiment is a device that controls each motor 2 that independently drives each wheel 1 of the vehicle 10. The motor control device 3 includes: a control information transceiver 31 that receives control information 41 from the host control device 4, the control information 41 including a torque command 412 for the motor 2 and driving state information 411 related to the driving state of the vehicle 10; a motor state acquisition unit 32 that acquires motor state information 321 related to the state of the motor 2; and a torque command switching unit 33 that switches, based on the control information 41 received from the host control device 4 and the motor state information 321 acquired by the motor state acquisition unit 32, whether to control the motor 2 according to the torque command 412 or to control the motor 2 according to a modified torque command 371 obtained by modifying the torque command 412.

[0056] Thus, the motor control device 3 can switch the torque command given to the motor 2 to the torque command 412 or the modified torque command 371 received from the host control device 4, depending on the driving state of the vehicle 10 and the state of the motor 2. Therefore, the motor control device 3 can switch the torque command given to the motor 2 to the modified torque command 371 that can suppress any reduction in reliability before the reliability of the motor 2 is reduced due to the driving state of the vehicle 10 and the state of the motor 2. Thus, according to this embodiment, it is possible to suppress any reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle.

[0057] Furthermore, in the motor control device 3 of the present embodiment, the torque command switching unit 33 determines whether the driving state of the vehicle 10 is a stable state in which the driving of the vehicle 10 is stable based on the driving state information 411. If the torque command switching unit 33 determines that the driving state is a stable state, it outputs a corrected torque command 371 that has been corrected to a value smaller than the torque command 412, and controls the motor 2 to be controlled based on the corrected torque command 371. If the torque command switching unit 33 determines that the driving state is not a stable state, it outputs the torque command 412, and controls the motor 2 to be controlled based on the torque command 412.

[0058] Thus, when the driving state of the vehicle 10 is not stable, the motor control device 3 can assign the torque command 412 adjusted by the host control device 4 to the motor 2 being controlled, thereby reliably ensuring driving performance and driving safety. When the driving state of the vehicle 10 is stable, the motor control device 3 can assign the corrected torque command 371, corrected to a value less than the torque command 412, to the motor 2 being controlled, thereby suppressing the operating rate of the motor 2 and preventing a reduction in reliability. Thus, according to this embodiment, the driving performance and driving safety of the vehicle 10 can be reliably ensured, while preventing a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle.

[0059] Furthermore, in the motor control device 3 of the present embodiment, the torque command switching unit 33 determines whether the state of the motor 2 to be controlled is a high operating state in which the operating rate of the motor 2 is high, based on the motor state information 321. If the torque command switching unit 33 determines that the state of the motor 2 to be controlled is a high operating state, the torque command switching unit 33 outputs a corrected torque command 371 that has been corrected to a value smaller than the torque command 412, and controls the motor 2 to be controlled according to the corrected torque command 371. If the torque command switching unit 33 determines that the state of the motor 2 to be controlled is not a high operating state, the torque command switching unit 33 outputs the torque command 412, and controls the motor 2 to be controlled according to the torque command 412.

[0060] Thus, when the motor 2 is in a high-speed operating state, the motor control device 3 can assign a corrected torque command 371, which has been corrected to a value less than the torque command 412, to the controlled motor 2. This reliably suppresses the operating rate of the motor 2 and reliably prevents a reduction in reliability. When the motor 2 is not in a high-speed operating state, the motor control device 3 can assign the torque command 412 adjusted by the host control device 4 to the controlled motor 2, thereby ensuring driving performance and driving safety. Thus, according to this embodiment, the driving performance and driving safety of the vehicle 10 can be ensured, while reliably preventing a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle.

[0061] Furthermore, in the motor control device 3 of the present embodiment, when the torque command switching unit 33 determines that the driving state is stable and the state of the controlled motor 2 is in the high operating state, the torque command switching unit 33 outputs a corrected torque command 371 corrected to a value smaller than the torque command 412, and controls the controlled motor 2 according to the corrected torque command 371. When the torque command switching unit 33 determines that the driving state is not stable, the torque command switching unit 33 outputs the torque command 412, regardless of whether the state of the controlled motor 2 is in the high operating state, and controls the controlled motor 2 according to the torque command 412.

[0062] Thus, when the driving state of vehicle 10 is not stable, motor control device 3 can reliably assign torque command 412 adjusted by host control device 4 to motor 2, thereby reliably ensuring the driving performance and driving safety of vehicle 10. When motor control device 3 determines that the driving state is stable and that motor 2 is in a high-speed operation state, it can assign a corrected torque command 371, corrected to a value less than torque command 412, to motor 2, thereby reliably suppressing the operating rate of motor 2 and reliably preventing a reduction in reliability. Thus, according to this embodiment, the driving performance and driving safety of vehicle 10 can be reliably ensured without sacrificing them, and a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle can be reliably prevented.

[0063] Furthermore, in the motor control device 3 of the present embodiment, the driving state information 411 includes at least one of the following: a torque command 412 for another motor 2 different from the one being controlled; the rotational speed of the other motor 2; and the steering angle of the other wheel 1 driven by the other motor 2. The torque command switching unit 33 calculates a difference between the motor 2 being controlled and the other motor 2, with respect to the at least one piece of information included in the driving state information 411. If the calculated difference is less than a threshold, the torque command switching unit 33 determines that the driving state of the vehicle 10 is stable. If the calculated difference is greater than the threshold, the torque command switching unit 33 determines that the driving state of the vehicle 10 is unstable.

[0064] Thus, the motor control device 3 can accurately determine whether the driving state of the vehicle 10 is stable based on the actual state. Therefore, the motor control device 3 can accurately switch between controlling the motor 2 corresponding to the torque command 412 adjusted by the host control device 4 and controlling the motor 2 corresponding to the corrected torque command 371 corrected to a value less than the torque command 412. Therefore, the motor control device 3 can appropriately strike a balance between ensuring the driving capability and driving safety of the vehicle 10 and suppressing a reduction in the reliability of the motor 2. Thus, according to this embodiment, while appropriately ensuring the driving capability and driving safety of the vehicle 10, it is possible to appropriately suppress a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle.

[0065] Furthermore, in the motor control device 3 of the present embodiment, the motor state information 321 includes at least one of the following: the temperature of the motor 2, the magnetic flux of the magnets constituting the motor 2, the demagnetization rate of the magnets, and the degree of deterioration of the coils constituting the motor 2. The torque command switching unit 33 determines that the state of the motor 2 to be controlled is in the high-speed operation state if the at least one of the information included in the motor state information 321 exceeds an allowable value, and determines that the state of the motor 2 to be controlled is not in the high-speed operation state if the at least one of the information included in the motor state information 321 does not exceed the allowable value.

[0066] Thus, the motor control device 3 can accurately determine whether the state of the controlled motor 2 is a high-speed operation state based on the actual state. Therefore, the motor control device 3 can accurately switch between controlling the motor 2 corresponding to the torque command 412 adjusted by the host control device 4 and controlling the motor 2 corresponding to the corrected torque command 371 corrected to a value less than the torque command 412. Therefore, the motor control device 3 can appropriately strike a balance between ensuring the driving capability and driving safety of the vehicle 10 and suppressing a reduction in the reliability of the motor 2. Thus, according to this embodiment, the driving capability and driving safety of the vehicle 10 can be appropriately ensured while also appropriately suppressing a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle.

[0067] Figure 5 It is an explanation Figure 3 FIG. 2 is a diagram showing another example of the motor state determination unit 36 ​​and the correction torque instruction calculation unit 37.

[0068] The control information transceiver 31 can receive the judgment result 413 of whether the state of the other motor 2 is in the high-speed operation state from the upper control device 4. In this case, the motor state judgment unit 36 ​​not only judges whether the state of the motor 2 of the control target is in the high-speed operation state, but also judges whether the motor 2 of the control target is in the high-speed operation state. Figure 5As shown, it is also possible to obtain a judgment result 413 about the state of the other motors 2. Then, Figure 5 The motor state determination unit 36 ​​shown outputs a determination result 362 on the states of all motors 2 of the vehicle 10 , including the motor 2 to be controlled and other motors 2 , to the correction torque command calculation unit 37 and the torque command selection unit 35 .

[0069] When it is determined that the state of the motor 2 to be controlled is the high-speed operation state, Figure 3 Likewise, Figure 5 The correction torque instruction calculation unit 37 shown calculates the correction torque instruction 371 corrected to a value smaller than the torque instruction 412 received from the host control device 4. When it is determined that the state of the motor 2 to be controlled is not the high-speed operation state and the state of the other motors 2 is determined to be the high-speed operation state, Figure 5 The illustrated correction torque command calculation unit 37 calculates a correction torque command 372 corrected to a value larger than the torque command 412 received from the host control device 4 .

[0070] Figure 5 The correction torque command calculation unit 37 outputs the calculated correction torque commands 371 and 372 to the torque command selection unit 35. The torque command selection unit 35 selects a torque command to be given to the controlled motor 2 based on the determination result 341 of the driving state determination unit 34 and the determination result 362 regarding the states of all the motors 2.

[0071] In particular, when the torque command selection unit 35 determines that the state of the motor 2 to be controlled is in the high operating state, it outputs a corrected torque command 371 that has been corrected to a value smaller than the torque command 412, and controls the motor 2 to be controlled based on the corrected torque command 371. On the other hand, when the torque command selection unit 35 determines that the state of the motor 2 to be controlled is not in the high operating state and that the state of the other motors 2 is in the high operating state, it outputs a corrected torque command 372 that has been corrected to a value larger than the torque command 412, and controls the motor 2 to be controlled based on the corrected torque command 372.

[0072] Thus, when the state of the controlled motor 2 is in a high-speed operating state, the motor control device 3 can assign a corrected torque command 371, which has been corrected to a value less than the torque command 412, to the controlled motor 2, thereby reliably suppressing a reduction in the reliability of the motor 2. Even if the corrected torque command 371, which has been corrected to a value less than the torque command 412, is assigned to another motor 2 in a high-speed operating state, the motor control device 3 can assign a corrected torque command 372, which has been corrected to a value greater than the torque command 412, to the controlled motor 2 not in a high-speed operating state. Therefore, the motor control device 3 can supplement the overall torque deficiency of the vehicle 10 with the motor 2 not in a high-speed operating state, thereby suppressing deceleration of the vehicle 10 due to insufficient torque of the vehicle 10. Thus, according to this embodiment, the driving capability and driving safety of the vehicle 10 can be reliably ensured, while reliably suppressing a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle.

[0073] It should be noted that Figure 5 The corrected torque instruction calculation unit 37 shown is capable of setting an upper limit value of the corrected torque instruction 372 when calculating the corrected torque instruction 372 that is corrected to a value greater than the torque instruction 412. Specifically, the corrected torque instruction calculation unit 37 sets the upper limit value of the corrected torque instruction 372 so that the tangential force generated on the wheel 1 driven by the motor 2 of the control object is less than the maximum tangential force Fmax that the wheel 1 can generate. Generally, if the maximum adhesion rate of the wheel 1 to the road surface is set to μmax and the load in the up and down directions of the wheel 1 is set to P, the maximum tangential force Fmax that the wheel 1 can generate is Fmax=μmax×P. If the tangential force generated on the wheel 1 due to the corrected torque instruction 372 is greater than the maximum tangential force Fmax, the wheel 1 slips. Therefore, Figure 5 The correction torque command calculation unit 37 shown sets the upper limit value of the correction torque command 372 so that the tangential force generated in the wheel 1 is equal to or less than the maximum tangential force Fmax that can be generated by the wheel 1 .

[0074] Thus, even when the corrected torque command 372, which has been corrected to a value greater than the torque command 412, is given to the controlled motor 2, the motor control device 3 can suppress slippage of the wheel 1. Thus, according to this embodiment, the driving capability and driving safety of the vehicle 10 can be more reliably ensured, and a reduction in the reliability of each motor 2 that independently drives each wheel 1 of the vehicle can be suppressed.

[0075] It should be noted that the present invention is not limited to the above-described embodiments, but includes a variety of variations. For example, the above-described embodiments are described in detail to clearly and easily explain the present invention, and are not necessarily limited to having all the described structures. In addition, a portion of the structure of a certain embodiment can be replaced with a structure of another embodiment, and a structure of another embodiment can be added to a structure of a certain embodiment. In addition, other structures can be added, deleted, or replaced with a portion of the structure of each embodiment.

[0076] Furthermore, the aforementioned components, functions, processing units, and the like may be partially or entirely implemented by hardware, for example, through integrated circuit design. Furthermore, the aforementioned components, functions, and the like may be implemented by software, with a processor interpreting and executing programs that implement the respective functions. Information such as programs, tables, and files that implement the respective functions may be stored in a recording device such as a memory, hard disk, or SSD (Solid State Drive), or in a recording medium such as an IC card, SD card, or DVD.

[0077] In addition, the control lines and information lines are shown as those necessary for explanation, and do not represent all the control lines and information lines required for the product. It can be assumed that almost all components are actually connected to each other.

[0078] Description of Reference Numerals

[0079] 1a~1d wheels, 2a~2d motors, 3, 3a~3d motor control devices, 31 control information transceiver, 32 motor state acquisition unit, 321 motor state information, 33 torque command switching unit, 371, 372 corrected torque command, 4 upper control device, 41 control information, 411 driving state information, 412 torque command, 413 judgment result, 10 vehicle.

Claims

1. A motor control device that controls each motor, each of which independently drives each wheel of a vehicle. The motor control device is characterized by comprising: a control information transceiver receiving unit configured to receive control information from a higher-level control device, the control information including a torque command to the electric motor and driving state information related to the driving state of the vehicle; a motor state acquisition unit that acquires motor state information related to the state of the motor; and A torque instruction switching unit switches whether to control the motor according to the torque instruction or to control the motor according to a corrected torque instruction obtained by correcting the torque instruction based on the control information received from the upper control device and the motor state information obtained by the motor state acquisition unit.

2. The motor control device according to claim 1, wherein: The torque command switching unit determines whether the driving state is a stable state in which driving of the vehicle is stable based on the driving state information. When it is determined that the driving state is the stable state, the torque command switching unit outputs the corrected torque command that is corrected to a value smaller than the torque command, so as to control the electric motor to be controlled according to the corrected torque command. When it is determined that the driving state is not the stable state, the torque command switching unit outputs the torque command so as to control the electric motor as the control target according to the torque command.

3. The motor control device according to claim 2, wherein: The torque command switching unit determines whether the state of the motor to be controlled is a high operating state in which the operating rate of the motor is high based on the motor state information. When it is determined that the state of the electric motor to be controlled is the high operating state, the torque command switching unit outputs the corrected torque command that is corrected to a value smaller than the torque command, so as to control the electric motor to be controlled according to the corrected torque command. When it is determined that the state of the electric motor as the control target is not the high operating state, the torque command switching unit outputs the torque command to control the electric motor as the control target according to the torque command.

4. The motor control device according to claim 3, wherein: When it is determined that the driving state is the stable state and the state of the electric motor as the controlled object is the high operating state, the torque command switching unit outputs the corrected torque command corrected to a value smaller than the torque command, so as to control the electric motor as the controlled object according to the corrected torque command. When it is determined that the driving state is not the stable state, the torque command switching unit outputs the torque command to control the electric motor of the control object according to the torque command regardless of whether the state of the electric motor of the control object is the high operating state.

5. The motor control device according to claim 2, wherein: The driving state information includes at least one of a torque command to another motor different from the control target, a rotation speed of the other motor, and a steering angle of the other wheel driven by the other motor. The torque command switching unit calculates a difference between the electric motor being the controlled object and the other electric motor based on the at least one information included in the driving state information. When the calculated difference is lower than a threshold value, the torque command switching unit determines that the driving state is the stable state. When the calculated difference is equal to or greater than the threshold value, the torque command switching unit determines that the driving state is not the stable state.

6. The motor control device according to claim 3, wherein: The motor state information includes at least one of the temperature of the motor, the magnetic flux of a magnet constituting the motor, the demagnetization ratio of the magnet, and the degree of deterioration of a coil constituting the motor. When the at least one information included in the motor state information exceeds an allowable value, the torque command switching unit determines that the state of the motor to be controlled is the high operating state. The torque command switching unit determines that the state of the electric motor as the control target is not the high operating state when the at least one information included in the electric motor state information does not exceed an allowable value.

7. The motor control device according to claim 2, wherein: The control information transceiver receives from the host control device a determination result of whether the state of another motor different from the control target is a high operating state in which the operating rate of the motor is high. The torque command switching unit determines whether the state of the electric motor to be controlled is the high operating state based on the electric motor state information. When it is determined that the state of the electric motor to be controlled is the high operating state, the torque command switching unit outputs the corrected torque command that is corrected to a value smaller than the torque command, so as to control the electric motor to be controlled according to the corrected torque command. When it is determined that the state of the electric motor of the control object is not the high-operation state and it is determined that the state of the other electric motor is the high-operation state, the torque instruction switching unit outputs the corrected torque instruction corrected to a value greater than the torque instruction to control the electric motor of the control object according to the corrected torque instruction.

8. The motor control device according to claim 7, wherein: When the correction torque instruction is calculated to be a value greater than the torque instruction, the torque instruction switching unit sets an upper limit value of the correction torque instruction so that the tangential force generated on the wheel driven by the electric motor of the control object is less than the maximum tangential force that the wheel can generate.

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