Slip determination device and vehicle

Abstract

To provide a slip determination device capable of determining whether a vehicle is slipping. [Solution] A slip determination device according to one embodiment of the present disclosure includes an electric motor control circuit capable of generating a first torque command value that fluctuates at a predetermined frequency and determining the torque of the electric motor based on the first torque command value and a second torque command value that corresponds to the driving operation of the vehicle driver, and a determination circuit capable of detecting the fluctuating component in the rotation speed of the electric motor at the above frequency and determining whether the vehicle is slipping based on the fluctuating component.

Description

[Technical Field]

[0001] The present disclosure relates to a slip determination device that determines slippage of a vehicle, and a vehicle equipped with such a slip determination device. [Background technology]

[0002] Vehicles such as automobiles may slip due to road conditions, for example. For example, Patent Document 1 discloses a technology for correcting the rotation speed of a motor when the resonant frequency of vibrations generated in the drivetrain is within a predetermined resonant frequency band that indicates a slip state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-039447 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle, it is desirable to be able to determine whether the vehicle is slipping, and it is expected that the ability to effectively determine whether the vehicle is slipping is being determined.

[0005] It is desirable to provide a slip determination device and a vehicle that can effectively determine whether a vehicle is slipping.

[0006] A slip determination device according to one embodiment of the present disclosure includes an electric motor control circuit and a determination circuit. The electric motor control circuit is capable of generating a first torque command value that fluctuates at a predetermined frequency and is capable of determining the torque of the electric motor based on the first torque command value and a second torque command value that corresponds to the driving operation of the vehicle driver. The determination circuit is capable of detecting a frequency fluctuation component in the rotation speed of the electric motor and is capable of determining whether the vehicle is slipping based on the fluctuation component.

[0007] A vehicle according to an embodiment of the present disclosure includes an electric motor, an electric motor control circuit, and a determination circuit. The electric motor is capable of generating a driving force used to run the vehicle. The electric motor control circuit is capable of generating a first torque command value that fluctuates at a predetermined frequency, and is capable of determining the torque of the electric motor based on the first torque command value and a second torque command value that corresponds to a driving operation by a driver of the vehicle. The determination circuit is capable of detecting a frequency fluctuation component in the rotation speed of the electric motor, and is capable of determining whether the vehicle is slipping based on the fluctuation component. [Effects of the Invention]

[0008] According to the slip determination device and vehicle according to an embodiment of the present disclosure, it is possible to effectively determine whether the vehicle is slipping. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of a vehicle according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a characteristic diagram showing an example of sensitivity characteristics that indicate the influence that the torque of the motor shown in FIG. 1 has on the rotation speed of the motor. [Figure 3] FIG. 3 is a timing diagram illustrating an example of the operation of the vehicle shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [Configuration example] 1 shows an example of the configuration of a vehicle 1 equipped with a control device according to one embodiment. The vehicle 1 is an electrically powered vehicle and includes a battery 11, a power control device 12, a motor 13, a drivetrain 14, wheels 15, a driving operation unit 16, a control circuit 20, and a user interface 17. The control circuit 20 and the user interface 17 constitute a slip determination device 100.

[0012] The battery 11 is configured to store power and to supply DC power to the power control device 12. The battery 11 is also configured to store the power supplied from the power control device 12.

[0013] The power control device 12 is configured to control the power supplied to the motor 13. The power control device 12 is configured to include, for example, an inverter, and converts the DC power supplied from the battery 11 into AC power based on a motor torque command value supplied from the control circuit 20, and supplies the AC power to the motor 13. The power control device 12 is also capable of supplying the power supplied from the motor 13 to the battery 11.

[0014] The motor 13 is configured to generate driving force, which is mechanical energy, based on the AC power supplied from the power control device 12. The motor 13 then transmits this driving force to the wheels 15 via the drivetrain 14. As a result, the vehicle 1 is able to travel based on this driving force. The motor 13 can also operate as a generator that generates electricity based on the mechanical energy supplied from the drivetrain 14, and is able to supply the generated AC power to the power control device 12.

[0015] The motor 13 has a rotation speed sensor 13A. The rotation speed sensor 13A is configured to detect the rotation speed of the motor 13. The rotation speed sensor 13A supplies data on the detected rotation speed of the motor 13 to the control circuit 20.

[0016] The drive system 14 is configured to transmit the driving force supplied from the motor 13 to the wheels 15. The drive system 14 includes various shafts such as a reducer, a differential gear, and a drive shaft that are provided in the driving force transmission path from the motor 13 to the wheels 15.

[0017] The wheels 15 are drive wheels of the vehicle 1, and are configured to rotate about their axles based on the driving force supplied from the drivetrain 14, thereby causing the vehicle 1 to travel on a road surface.

[0018] The driving operation unit 16 includes a steering wheel, an accelerator pedal, a brake pedal, various levers, and the like that are operated by the driver when driving the vehicle 1.

[0019] The control circuit 20 is, for example, an ECU (Electronic Control Unit), and is configured using, for example, one or more processors, one or more memories, etc. The control circuit 20 can operate as a torque command value generator 21, a pulsating torque command value generator 22, a motor torque command value generator 23, and a slip determination unit 24 by executing software.

[0020] The torque command value generating unit 21 is configured to generate a torque command value indicating a command value for torque of the motor 13, based on the driver's operation of the accelerator pedal of the driving operation unit 16. The torque command value generating unit 21 also supplies data on the generated torque command value to the pulsating torque command value generating unit 22.

[0021] The pulsating torque command value generating unit 22 is configured to generate a pulsating torque command value that fluctuates at a predetermined frequency f0. The pulsating torque command value generating unit 22 generates a pulsating torque command value having an amplitude corresponding to the torque command value generated by the torque command value generating unit 21. Specifically, the pulsating torque command value generating unit 22 generates the pulsating torque command value such that the amplitude of the fluctuating pulsating torque command value is, for example, about 10% of the torque command value. Furthermore, the pulsating torque command value generating unit 22 supplies data on the amplitude of the generated pulsating torque command value to the slip determination unit 24.

[0022] The motor torque command value generation unit 23 is configured to generate a motor torque command value indicating a command value for the torque of the motor 13, based on the torque command value generated by the torque command value generation unit 21 and the pulsating torque command value generated by the pulsating torque command value generation unit 22. Specifically, the motor torque command value generation unit 23 is configured to generate the motor torque command value by adding together the torque command value generated by the torque command value generation unit 21 and the pulsating torque command value generated by the pulsating torque command value generation unit 22.

[0023] The slip determination unit 24 is configured to detect a fluctuation component at frequency f0 in the rotation speed of the motor 13 based on the detection result of the rotation speed sensor 13A, and to determine whether the vehicle 1 is slipping based on the fluctuation component. That is, since the pulsating torque command value fluctuates at frequency f0, the rotation speed of the motor 13 includes a fluctuation component at frequency f0. The magnitude of this fluctuation component changes depending on the slip state of the vehicle 1.

[0024] Fig. 2 shows an example of sensitivity characteristics indicating the effect that the torque of the motor 13 has on the rotation speed of the motor 13 in the vehicle 1. The horizontal axis represents frequency, and the vertical axis represents gain. In Fig. 2, the characteristic W1 shown by the solid line represents the characteristic when the vehicle 1 is not slipping, and the characteristic W2 shown by the dashed line represents the characteristic when the coefficient of friction between the wheels 15 and the road surface is zero and the vehicle 1 is completely slipping.

[0025] When the vehicle 1 is not slipping (characteristic W1), resonance occurs at frequency f1. For example, the drive shaft included in the drivetrain 14 mechanically has spring and damper components, so torsional resonance can occur in the rotational direction of the drive shaft. When the vehicle 1 is not slipping, the wheels 15 rotate to move the vehicle 1, which places a large mechanical load on the drivetrain 14. Therefore, as shown in FIG. 2, the torsional natural frequency is a low frequency f1 (for example, about 9 Hz).

[0026] When the vehicle 1 slips, the torsional natural frequency gradually increases from frequency f1 according to the degree of slip. That is, as the degree of slip increases in the vehicle 1, the mechanical load on the drivetrain 14 gradually decreases, and the torsional natural frequency gradually increases. When the vehicle 1 is completely slipping (characteristic W2), the torsional natural frequency becomes a high frequency f2 (for example, approximately 28 Hz).

[0027] In the frequency range higher than frequency f1 and lower than frequency f2, the gain of the sensitivity characteristic changes depending on the slip state of the vehicle 1. That is, the smaller the degree of slip, the higher the gain, and the greater the degree of slip, the lower the gain.

[0028] In the vehicle 1, the frequency f0 at which the pulsating torque command value fluctuates is set to a frequency within this frequency range. Since the pulsating torque command value fluctuates at the frequency f0, the rotation speed of the motor 13 includes a fluctuation component at the frequency f0. As shown in FIG. 2, the sensitivity characteristic changes depending on the slip state of the vehicle 1, and therefore the magnitude of the fluctuation component of the rotation speed of the motor 13 changes depending on the slip state of the vehicle 1. Therefore, the slip determination unit 24 can determine whether the vehicle 1 is slipping based on the magnitude of the fluctuation component at the frequency f0.

[0029] Specifically, as will be described later, the slip determination unit 24 generates a threshold value based on data on the amplitude of the pulsating torque command value supplied from the pulsating torque command value generation unit 22. Then, the slip determination unit 24 compares the amplitude of the fluctuation component of the frequency f0 in the rotation speed of the motor 13 with this threshold value to determine whether the vehicle 1 is slipping.

[0030] The user interface 17 is configured to provide information to the driver using visual and audible signals, and is configured to include a display device such as a liquid crystal display, various indicators, a speaker, etc. The user interface 17 is capable of notifying the driver of the determination result of the slip determination unit 24.

[0031] Here, the torque command value generating unit 21, the pulsating torque command value generating unit 22, and the motor torque command value generating unit 23 of the control circuit 20 correspond to a specific example of an "electric motor control circuit" in an embodiment of the present disclosure. The pulsating torque command value corresponds to a specific example of a "first torque command value" in an embodiment of the present disclosure. The torque command value corresponds to a specific example of a "second torque command value" in an embodiment of the present disclosure. The slip determining unit 24 of the control circuit 20 corresponds to a specific example of a "determination circuit" in an embodiment of the present disclosure. The user interface 17 corresponds to a specific example of a "user interface" in an embodiment of the present disclosure. The motor 13 corresponds to a specific example of an "electric motor" in an embodiment of the present disclosure. The drivetrain 14 corresponds to a specific example of a "drivetrain" in an embodiment of the present disclosure. The wheels 15 correspond to a specific example of a "wheel" in an embodiment of the present disclosure. The frequency f1 corresponds to a specific example of a "first frequency" in an embodiment of the present disclosure. The frequency f2 corresponds to a specific example of a "second frequency" in an embodiment of the present disclosure.

[0032] [Actions and Actions] Next, the operation and function of the vehicle 1 of this embodiment will be described.

[0033] (Overview of overall operation) First, the operation of vehicle 1 will be described with reference to FIG. 1. Battery 11 stores power and supplies DC power to power control device 12. Power control device 12 controls the power supplied to motor 13. Motor 13 generates driving force, which is mechanical energy, based on the AC power supplied from power control device 12. Rotation speed sensor 13A of motor 13 detects the rotation speed of motor 13. Motor 13 also operates as a generator that generates power based on the mechanical energy supplied from drivetrain 14 and supplies the generated AC power to power control device 12. In this case, power control device 12 supplies the power supplied from motor 13 to battery 11, and battery 11 stores the power supplied from power control device 12. Drivetrain 14 transmits the driving force supplied from motor 13 to wheels 15. Based on the driving force supplied from drivetrain 14, wheels 15 rotate about their axles, causing vehicle 1 to travel on a road surface.

[0034] The torque command value generation unit 21 of the control circuit 20 generates a torque command value indicating a command value for torque of the motor 13, based on the driver's operation of the accelerator pedal of the driving operation unit 16. The pulsating torque command value generation unit 22 generates a pulsating torque command value that fluctuates at a predetermined frequency f0. The motor torque command value generation unit 23 generates a motor torque command value indicating a command value for torque of the motor 13, based on the torque command value generated by the torque command value generation unit 21 and the pulsating torque command value generated by the pulsating torque command value generation unit 22. The slip determination unit 24 detects a fluctuation component at frequency f0 in the rotation speed of the motor 13 based on the detection result of the rotation speed sensor 13A, and determines whether the vehicle 1 is slipping based on the fluctuation component. The user interface 17 notifies the driver of the determination result of the slip determination unit 24.

[0035] (Detailed operation) FIG. 3 shows an example of the operation of the vehicle 1, where (A) shows the torque of the motor 13, (B) shows the acceleration of the vehicle 1, (C) shows the slip ratio, and (D) shows the fluctuation component of the rotation speed of the motor 13 at frequency f0. The horizontal axis represents time. One scale on the horizontal axis represents 0.5 seconds.

[0036] In this example, the driver depresses the accelerator pedal to accelerate the vehicle 1. The torque command value generating unit 21 gradually increases the torque command value based on the driver's operation of the accelerator pedal. The pulsating torque command value generating unit 22 generates a pulsating torque command value that has an amplitude of about 10% of the torque command value and fluctuates at a frequency f0. The motor torque command value generating unit 23 generates a motor torque command value by adding together the torque command value generated by the torque command value generating unit 21 and the pulsating torque command value generated by the pulsating torque command value generating unit 22. The power control device 12 converts the DC power supplied from the battery 11 to AC power based on this motor torque command value and supplies this AC power to the motor 13. The motor 13 generates a driving force, which is mechanical energy, based on this AC power. As shown in FIG. 3(A), the torque of the motor 13 increases over time while fluctuating at a frequency f0. Accordingly, the acceleration of the vehicle 1 increases as shown in FIG. 3(B).

[0037] The rotation speed sensor 13A of the motor 13 detects the rotation speed of the motor 13. The slip determination unit 24 extracts a fluctuation component of frequency f0 by, for example, performing band-pass filter processing based on the time-series data on the rotation speed of the motor 13. In the period before around timing t1, as shown in FIG. 3(C), the slip ratio is sufficiently low and the vehicle 1 is not slipping. When the vehicle 1 is not slipping, as shown in FIG. 3(D), the amplitude of the fluctuation component gradually increases as indicated by dashed lines W3 and W4. That is, the amplitude of the fluctuation component gradually increases in response to a gradual increase in the pulsating torque command value.

[0038] Then, in a period after around timing t1, as shown in FIG. 3(C), the slip ratio begins to increase. That is, the vehicle 1 begins to slip. As a result, the increase in acceleration of the vehicle 1 stops, as shown in FIG. 3(B). Then, the amplitude of the fluctuation component of the rotation speed of the motor 13 becomes smaller than the amplitude indicated by the dashed lines W3 and W4. For example, at timing t2, the amplitude A2 of the fluctuation component is smaller than the amplitude A1 when the vehicle 1 is not slipping. That is, as shown in FIG. 2, the greater the degree of slip, the lower the gain, and therefore the smaller the amplitude of the fluctuation component. The slip determination unit 24 determines whether the vehicle 1 is slipping based on the amplitude of this fluctuation component.

[0039] Specifically, the slip determination unit 24 estimates the amplitude of the fluctuation component of the rotation speed of the motor 13 when the vehicle 1 is not slipping, based on data on the amplitude of the pulsating torque command value supplied from the pulsating torque command value generation unit 22. Then, the slip determination unit 24 generates a threshold value based on the estimated amplitude. For example, at timing t2, the slip determination unit 24 estimates amplitude A1. Then, the slip determination unit 24 sets a value slightly smaller than this amplitude A1 as the threshold value.

[0040] The slip determination unit 24 calculates the amplitude of the fluctuation component by obtaining the difference between the maximum and minimum values ​​of the fluctuation component extracted by the band-pass filter, as shown in Fig. 3(D).The slip determination unit 24 then compares the amplitude of this fluctuation component with a threshold value to determine whether the vehicle 1 is slipping. Specifically, if the amplitude of the fluctuation component is greater than the threshold value, the slip determination unit 24 determines that the vehicle 1 is not slipping.On the other hand, if the amplitude of the fluctuation component is smaller than the threshold value, the slip determination unit 24 determines that the vehicle 1 is slipping.

[0041] The user interface 17 notifies the driver of the determination result of the slip determination unit 24. A threshold value is generated. Specifically, for example, the user interface 17 may be configured to light an indicator or emit a predetermined sound when the vehicle 1 is skidding. When the driver is notified that the vehicle 1 is skidding, the driver can, for example, reduce the amount of depression of the accelerator pedal. This makes it possible to suppress skidding in the vehicle 1, thereby achieving safe driving.

[0042] In this way, slip determination device 100 is equipped with an electric motor control circuit (torque command value generator 21, pulsating torque command value generator 22, motor torque command value generator 23) that can generate a first torque command value (pulsating torque command value) that fluctuates at a predetermined frequency f0 and that can determine the torque of the electric motor (motor 13) based on the first torque command value (pulsating torque command value) and a second torque command value (torque command value) that corresponds to the driving operation of the driver of vehicle 1, and a determination circuit (slip determination unit 24) that can detect a fluctuation component at frequency f0 in the rotation speed of the electric motor (motor 13) and determine whether or not vehicle 1 is slipping based on the fluctuation component. This allows slip determination device 100 to effectively determine whether or not vehicle 1 is slipping.

[0043] That is, for example, when determining whether the vehicle 1 is slipping based on a change in the resonant frequency, as in the technology described in Patent Document 1, it may take some time to accurately detect the change in frequency. On the other hand, the slip determination device 100 determines whether the vehicle 1 is slipping based on the fluctuation component at frequency f0, and therefore can detect a change in the magnitude of the fluctuation component in a short time. Therefore, the slip determination device 100 can effectively determine whether the vehicle 1 is slipping.

[0044] Furthermore, in the slip determination device 100, the determination circuit (slip determination unit 24) is configured to be able to determine that the vehicle 1 is slipping when the magnitude of the fluctuation component is smaller than a threshold value. This allows the slip determination device 100 to determine whether the vehicle 1 is slipping simply by comparing the magnitude of the fluctuation component with the threshold value. Therefore, the slip determination device 100 can effectively determine whether the vehicle 1 is slipping.

[0045] Furthermore, in the slip determination device 100, the electric motor control circuit (torque command value generation unit 21, pulsating torque command value generation unit 22, motor torque command value generation unit 23) can generate a first torque command value so that the amplitude of the first torque command value (pulsating torque command value) fluctuating at frequency f0 corresponds to the second torque command value (torque command value), and the determination circuit (slip determination unit 24) can generate a threshold value corresponding to the amplitude of the first torque command value (pulsating torque command value). As a result, in the vehicle 1, for example, when acceleration is small, the amplitude of the pulsating torque command value can be reduced, and when acceleration is large, the amplitude of the pulsating torque command value can be increased. In this way, the amplitude of the pulsating torque command value can be set to an appropriate value. And, in the vehicle 1, even when the amplitude of the pulsating torque command value changes in this way, the threshold value can be set to an appropriate value. As a result, in the vehicle 1, it can effectively determine whether the vehicle 1 is slipping.

[0046] Furthermore, in the slip determination device 100, the frequency f0 is higher than the first frequency (frequency f1) and lower than the second frequency (frequency f2), the first frequency (frequency f1) being the torsional natural frequency of the drivetrain 14 that transmits the driving force of the electric motor (motor 13) to the wheels 15 when the vehicle 1 is not slipping, and the second frequency (frequency f2) being the torsional natural frequency of the drivetrain 14 when the coefficient of friction between the wheels 15 of the vehicle 1 and the road surface is zero. In this frequency range from frequency f1 to f2, as shown in FIG. 2, the gain of the sensitivity characteristic changes depending on the slip state of the vehicle 1. For example, at frequencies higher than frequency f2, this gain does not change depending on the slip state of the vehicle 1. Furthermore, frequencies lower than frequency f1 are used for the vehicle 1 to travel and are frequencies at which people are likely to feel shaking. Therefore, in the slip determination device 100, the frequency f0 of the pulsating torque command value is set to a frequency higher than frequency f1 and lower than frequency f2. As a result, in the slip determination device 100, the gain of the sensitivity characteristic changes depending on the slip state of the vehicle 1, so it is possible to determine whether the vehicle 1 is slipping. Furthermore, the slip determination device 100 can prevent torque fluctuations of the motor 13 according to the pulsating torque command value from affecting the behavior of the vehicle 1, making it difficult for the driver to perceive these torque fluctuations. As a result, the vehicle 1 can effectively determine whether the vehicle 1 is slipping.

[0047] Furthermore, the slip determination device 100 is further provided with a user interface 17 that notifies the driver when the determination circuit (slip determination unit 24) determines that the vehicle 1 is slipping. This allows the driver to more reliably determine whether the vehicle 1 is slipping. That is, for example, the driver can generally determine the vehicle's running state by feeling the vibration of the vehicle. However, it is more difficult for the driver to determine whether the vehicle is slipping in an electric vehicle than in a vehicle equipped with an internal combustion engine. In the vehicle 1, the user interface 17 notifies the driver when it is determined that the vehicle 1 is slipping, so the driver can more reliably determine whether the vehicle 1 is slipping. Then, the driver can, for example, reduce the amount of depression of the accelerator pedal. This allows the vehicle 1 to drive safely.

[0048] [effect] As described above, this embodiment is provided with an electric motor control circuit that can generate a first torque command value that fluctuates at a predetermined frequency and that can determine the torque of the electric motor based on the first torque command value and a second torque command value that corresponds to the driving operation of the driver of the vehicle, and a determination circuit that can detect a fluctuation component at frequency in the rotation speed of the electric motor and can determine whether or not the vehicle is slipping based on the fluctuation component, so that it can effectively determine whether or not the vehicle is slipping.

[0049] In this embodiment, the determination circuit is configured to be able to determine that the vehicle 1 is slipping when the magnitude of the fluctuation component is smaller than a threshold value, so that it is possible to effectively determine whether the vehicle is slipping.

[0050] In this embodiment, the motor control circuit is capable of generating the first torque command value so that the amplitude at which the first torque command value fluctuates with frequency corresponds to the amplitude of the second torque command value, and the determination circuit is capable of generating a threshold value corresponding to the amplitude of the first torque command value, so that it is possible to effectively determine whether the vehicle is slipping.

[0051] In this embodiment, the frequencies are higher than the first frequency and lower than the second frequency, the first frequency being the torsional natural frequency of the drivetrain that transmits the driving force of the electric motor to the wheels 15 when the vehicle is not slipping, and the second frequency being the torsional natural frequency of the drivetrain when the coefficient of friction between the vehicle wheels and the road surface is zero, so that it is possible to effectively determine whether the vehicle is slipping.

[0052] Although the present technology has been described above by giving embodiments, the present technology is not limited to these embodiments and can be modified in various ways.

[0053] For example, in the above embodiment, the user interface 17 lights up an indicator or emits a predetermined sound when the vehicle 1 is skidding, but this is not limited to this. Various methods can be used to notify the driver that the vehicle 1 is skidding.

[0054] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0055] Furthermore, the present disclosure may take the following aspects.

[0056] (1) an electric motor control circuit capable of generating a first torque command value that fluctuates at a predetermined frequency and determining the torque of the electric motor based on the first torque command value and a second torque command value that corresponds to a driving operation by a driver of the vehicle; a determination circuit capable of detecting a fluctuation component at the frequency in the rotation speed of the electric motor and determining whether the vehicle is slipping based on the fluctuation component; A slip determination device comprising: (2) The determination circuit is capable of determining that the vehicle is slipping when the magnitude of the fluctuation component is smaller than a threshold value. The slip determination device according to (1) above. (3) the electric motor control circuit is capable of generating the first torque command value such that an amplitude by which the first torque command value fluctuates at the frequency corresponds to an amplitude corresponding to the second torque command value; The determination circuit is capable of generating the threshold value according to the amplitude of the first torque command value. The slip determination device according to (2) above. (4) the frequency is higher than the first frequency and lower than the second frequency; the first frequency is a torsional natural frequency of a drivetrain that transmits the driving force of the electric motor to wheels when the vehicle is not slipping, The second frequency is a torsional natural frequency of the driveline when the coefficient of friction between the wheels of the vehicle and the road surface is zero. The slip determination device according to any one of (1) to (3). (5) The vehicle further includes a user interface that notifies the driver when the determination circuit determines that the vehicle is slipping. The slip determination device according to any one of (1) to (4). (6) an electric motor capable of generating driving force used for running the vehicle; an electric motor control circuit capable of generating a first torque command value that fluctuates at a predetermined frequency and determining a torque of the electric motor based on the first torque command value and a second torque command value that corresponds to a driving operation by a driver of the vehicle; a determination circuit capable of detecting a fluctuation component at the frequency in the rotation speed of the electric motor and determining whether the vehicle is slipping based on the fluctuation component; A vehicle equipped with. [Explanation of symbols]

[0057] 1...vehicle, 11...battery, 12...power control device, 13...motor, 13A...rotation speed sensor, 14...drive system, 15...wheel, 16...driving operation unit, 17...user interface, 20...control circuit, 21...torque command value generation unit, 22...pulsating torque command value generation unit, 23...motor torque command value generation unit, 24...slip determination unit, 100...slip determination device

Claims

1. an electric motor control circuit capable of generating a first torque command value that fluctuates at a predetermined frequency and determining a torque of the electric motor based on the first torque command value and a second torque command value that corresponds to a driving operation by a driver of the vehicle; a determination circuit capable of detecting a fluctuation component at the frequency in the rotation speed of the electric motor and determining whether the vehicle is slipping based on the fluctuation component; A slip determination device comprising:

2. The determination circuit is capable of determining that the vehicle is slipping when the magnitude of the fluctuation component is smaller than a threshold value. The slip determination device according to claim 1 .

3. the electric motor control circuit is capable of generating the first torque command value such that an amplitude by which the first torque command value fluctuates at the frequency corresponds to an amplitude corresponding to the second torque command value; The determination circuit is capable of generating the threshold value according to the amplitude of the first torque command value. The slip determination device according to claim 2 .

4. the frequency is higher than the first frequency and lower than the second frequency; the first frequency is a torsional natural frequency of a drivetrain that transmits the driving force of the electric motor to wheels when the vehicle is not slipping, The second frequency is a torsional natural frequency of the drivetrain when the coefficient of friction between the wheels of the vehicle and the road surface is zero. The slip determination device according to claim 1 .

5. The vehicle further includes a user interface that notifies the driver when the determination circuit determines that the vehicle is slipping. The slip determination device according to claim 1 .

6. an electric motor capable of generating driving force used for running the vehicle; an electric motor control circuit capable of generating a first torque command value that fluctuates at a predetermined frequency and determining a torque of the electric motor based on the first torque command value and a second torque command value that corresponds to a driving operation by a driver of the vehicle; a determination circuit capable of detecting a fluctuation component at the frequency in the rotation speed of the electric motor and determining whether the vehicle is slipping based on the fluctuation component; A vehicle equipped with.

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