Motor control device
The motor control device addresses vehicle vibrations and noise by combining required torque with vibration damping torque and adjusting gain based on torque magnitude, effectively suppressing oscillations and noise in electric vehicles.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2026-04-03
AI Technical Summary
Existing motor control devices for electric vehicles fail to effectively suppress vehicle vibrations and abnormal noise caused by torque pulsations and oscillations, particularly when the torque command value crosses zero, leading to torsion and sprung pitch issues.
A motor control device that outputs torque equal to the sum of required torque and vibration damping torque, with a gain adjustment mechanism that varies based on the absolute value of the required torque, ensuring effective vibration suppression and noise reduction.
The solution effectively suppresses torsion and sprung pitch vibrations, reducing abnormal noise by dynamically adjusting the gain to match the required vibration damping torque, thereby enhancing the stability and comfort of the vehicle.
Smart Images
Figure 2026058140000001_ABST
Abstract
Description
Technical Field
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[0001] The present disclosure relates to a control device for a motor.
Background Art
[0002] [[ID=IMPORTANT]]Conventionally, as a control device for this type of motor, there has been proposed one used in an electric vehicle including an engine and a motor (motor generator) connected to a drive shaft connected to an axle via a gear mechanism (see, for example, Patent Document 1). In this device, the sum of a compensation torque for reducing the pulsation component of the engine torque and the required torque of the motor is used as the torque command value for the motor. And in this device, when the average value of the torque command value is less than the absolute value (amplitude) of the torque command value, the torque command value is corrected so that a value with the opposite positive / negative sign to the average value of the torque command value is not commanded to the motor, thereby suppressing vehicle vibration and abnormal noise when the torque command value crosses 0 Nm.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
[0007] The motor control device of this disclosure is A motor control device for an electric vehicle equipped with a motor that outputs power to a drive shaft connected to an axle via a gear mechanism, wherein the motor is controlled so that a torque equal to the sum of the required torque and the effective vibration damping torque obtained by multiplying the required vibration damping torque required for vibration suppression by a gain is output to the drive shaft, When the absolute value of the required torque is less than a first value that is greater than or equal to 0 and greater than 0, the gain is set to a predetermined value of 0 or greater than 0 and less than 1. When the absolute value of the requested torque is greater than or equal to the first value, the gain is changed from a value of 0 or the predetermined value towards a value of 1, such that the gain is greater when the absolute value of the requested torque is large compared to when it is small. This is the gist of it.
[0008] In the motor control device of this disclosure, the motor is controlled so that the torque output to the drive shaft is the sum of the required torque for driving and the vibration damping torque obtained by multiplying the required vibration damping torque for suppressing vibration by a gain. When the absolute value of the required torque is greater than or equal to 0 and less than a first value greater than 0, the gain is set to 0 or a predetermined value greater than 0 and less than 1. This suppresses the oscillation of the torque output from the motor between positive and negative torque, thereby suppressing torsion of the drive system and sprung pitch. Furthermore, when the absolute value of the required torque is greater than or equal to the first value, the gain is changed from 0 or the predetermined value towards 1, so that when the absolute value of the required torque is large, the gain is larger than when it is small. This brings the effective vibration damping torque closer to the required vibration damping torque, thereby suppressing torsion of the drive system and sprung pitch as vibration of the sprung structure above the suspension. As a result, abnormal noise can be suppressed. Here, "first value" and "predetermined value" can be values slightly larger than 0, etc.
[0009] In the motor control device of this disclosure, when the absolute value of the required torque is greater than or equal to the first value and less than the second value greater than the first value, the gain may be changed from a value of 0 or the predetermined value towards a value of 1, so that it is larger when the absolute value of the required torque is large compared to when it is small, and when the absolute value of the required torque is greater than or equal to the second value, the gain may be set to a value of 1. In this way, abnormal noise can be suppressed more effectively. [Brief explanation of the drawing]
[0010] [Figure 1] This is a schematic diagram of an electric vehicle equipped with a motor control device according to an embodiment of the disclosure. [Figure 2] A block diagram showing an example of a functional block used in setting torque commands by the ECU. [Figure 3] This is an explanatory diagram showing an example of the relationship between the absolute value of the required torque and the gain. [Figure 4] This is an explanatory diagram showing an example of the time evolution of the required torque, torque command, required vibration damping torque, effective vibration damping torque, and gain. [Modes for carrying out the invention]
[0011] Embodiments of this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of an electric vehicle equipped with a motor control device according to an embodiment of this disclosure. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32 for driving, an inverter 34, a battery 36 as an energy storage device, and an electronic control unit (hereinafter referred to as "ECU") 50. The electric vehicle 20 also includes, although not shown, a suspension system that connects the drive wheels 22a, 22b and driven wheels (not shown) to the vehicle body to suppress the transmission of shocks and vibrations from the road surface to the passenger compartment.
[0012] The motor 32 is configured as a three-phase AC motor and comprises a rotor with permanent magnets embedded in the rotor core and a stator with three-phase coils wound around the stator core. The rotor of the motor 32 is connected to a drive shaft 26 which is linked to the drive wheels 22a and 22b via a differential gear (gear mechanism) 24.
[0013] The inverter 34 is used to drive the motor 32 and is connected to the power line 38. When a DC voltage is applied to the inverter 34, the ECU 50 controls the switching of multiple switching elements in the inverter 34, thereby forming a rotating magnetic field in the three-phase coil of the motor 32 and driving the motor 32 to rotate.
[0014] The battery 36 is configured as, for example, a lithium-ion secondary battery, a nickel-metal hydride secondary battery, or a fuel cell with a rated voltage of several hundred volts, and is connected to the power line 38.
[0015] The ECU 50 is equipped with a microcomputer, which has a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the ECU 50 via the input ports. Examples of signals input to the ECU 50 include the rotational position θm from a rotational position sensor (e.g., resolver) 32a that detects the rotational position of the rotor of the motor 32, and the phase currents Iv and Iw from a current sensor that detects the V-phase and W-phase currents of the motor 32. Other examples include the voltage Vb from a voltage sensor attached between the terminals of the battery 36, and the current Ib from a current sensor attached to the output terminal of the battery 36. Other examples include the start signal from the start switch 60, the shift position SP from a shift sensor 62 that detects the operating position of the shift lever 61, the accelerator opening Acc from an accelerator sensor 64 that detects the amount of depression of the accelerator pedal 63, the brake pedal position from a brake sensor 66 that detects the amount of depression of the brake pedal 65, and the vehicle speed V from a vehicle speed sensor 67. Battery temperature Tb from a temperature sensor that detects the temperature of the battery 36 can also be mentioned.
[0016] From the ECU 50, various control signals are output via the output ports. Examples of the signals output from the ECU 50 include, for example, a control signal to the inverter 34. The ECU 50 calculates the state of charge SOC of the battery 36 based on the current Ib of the battery 36 from the current sensor. The state of charge SOC is the ratio of the capacity of the electric power that can be discharged from the battery 36 to the total capacity of the battery 36.
[0017] In the electric vehicle 20 of the embodiment thus configured, the ECU 50 performs switching control of a plurality of transistors of the inverter 34 so that the motor 32 is driven by the torque command Tm*.
[0018] Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly the operation when setting the torque command Tm*, will be described. FIG. 2 is a block diagram showing an example of a functional block in the setting of the torque command by the ECU. As the functional block of FIG. 2, the ECU 50 includes a target torque setting unit 500, a required torque setting unit 510, a required vibration damping torque setting unit 520, a gain setting unit 530, an execution vibration damping torque setting unit 540, and a torque command setting unit 550.
[0019] The target torque setting unit 500 sets a target torque Tdp as a target value of the torque to be output to the drive shaft 26 based on the accelerator opening Acc and the vehicle speed V. The target torque setting unit 500 sets the target torque Tdp to be larger when the accelerator opening Acc is large than when it is small, and to be larger when the vehicle speed V is high than when it is low.
[0020] The required torque setting unit 510 sets a required torque Td* so that the torque output to the drive shaft 26 changes at a first rate from the current torque toward the target torque Tdp. The "first rate" may be, for example, a rate at which no shock occurs due to a sudden change in the torque output to the drive shaft 26.
[0021] The required vibration damping torque setting unit 520 sets a required vibration damping torque Tsreq for suppressing the vibration of the vehicle. The required vibration damping torque setting unit 520 sets the required vibration damping torque Tsreq as a torque with an amplitude a centered on the value 0, having a frequency f identical to that of the vibration generated in the vehicle and a phase opposite to that of the vibration generated in the vehicle. The frequency f can include, for example, a frequency fpb determined in advance by experiments, analysis, machine learning, etc. as the fundamental frequency of pitching. The amplitude a is set to a value a1 when traveling on a flat road and to a value a2 greater than the value a1 when traveling on a road surface with relatively large unevenness. The values a1 and a2 are values determined in advance by experiments, analysis, or machine learning. The required vibration damping torque setting unit 520 determines whether the vehicle is traveling on a flat road or on a road surface with relatively large unevenness by using the map information stored in a navigation system (not shown) and the road surface information at each location.
[0022] The gain setting unit 530 sets a gain G using the required torque Td*. FIG. 3 is an explanatory diagram showing an example of the relationship between the absolute value of the required torque and the gain. The gain setting unit 530 sets the gain G to the value 0 when the absolute value |Td*| of the required torque Td* is equal to or greater than 0 and less than a first value Td1 greater than 0. Then, when the absolute value |Td*| is equal to or greater than the first value Td1 and less than a second value Td2 greater than the first value Td1, the gain setting unit 530 changes the gain G at a second rate so that it increases as the absolute value |Td*| increases, from the value 0 to the value 1. Further, when the absolute value |Td*| of the required torque Td* is equal to or greater than the second value Td2, the gain setting unit 530 sets the gain G to the value 1.
[0023] The operational vibration damping torque setting unit 540 sets the operational vibration damping torque Tse by multiplying the required vibration damping torque Tsreq by the gain G. When the absolute value |Td*| of the required torque Td* is 0 or greater and less than the first value Td1, the gain G is 0, so the operational vibration damping torque setting unit 540 sets the operational vibration damping torque Tse to 0. When the absolute value |Td*| of the required torque Td* is 1 or greater and less than the second value Td2, the gain G changes from 0 to 1 such that it becomes larger when the absolute value |Td*| is large compared to when it is small, so the amplitude of the operational vibration damping torque Tse changes such that it becomes larger when the absolute value |Td*| is large compared to when it is small. When the absolute value |Td*| of the required torque Td* is greater than or equal to the second value Td2, the gain G is 1, so the execution vibration damping torque setting unit 540 sets the execution vibration damping torque Tse to a torque with the same amplitude as the required vibration damping torque Tsreq.
[0024] The torque command setting unit 550 sets the torque command Tm* to the sum of the required torque Td* and the vibration damping torque Tse, multiplied by the reciprocal of the gear ratio Gr of the differential gear 24 (= (Td* + Tsc) / Gr). The ECU 50 controls the switching of multiple transistors of the inverter 34 based on the torque command Tm* thus set.
[0025] Figure 4 is an explanatory diagram showing an example of the time evolution of the required torque, torque command, required vibration damping torque, effective vibration damping torque, and gain. In the figure, the solid line represents the torque command Tm*, the effective vibration damping torque Tse, and the gain G. The dashed line represents the required torque Td* and the required vibration damping torque Tsreq.
[0026] When the absolute value |Td*| of the required torque Td* is greater than or equal to 0 and less than the first value Td1, that is, when the absolute value |Td*| is near 0, the torque command Tm* is set to the required torque Td*, thereby suppressing the oscillation of the torque output from the motor 32 between positive and negative torques, crossing the value of 0. This suppresses vibrations caused by the twisting of the drive shaft 26 and vibrations (pitch) of the sprung mass structure above the suspension system, thereby suppressing abnormal noises.
[0027] When the absolute value of the required torque Td* |Td*| is greater than or equal to the first value Td1 and less than the second value Td2, the torque command Tm* becomes the required torque Td* plus the effective vibration damping torque Tse. Since the effective vibration damping torque Tse approaches the required vibration damping torque Tsreq, vibrations caused by the twisting of the drive shaft 26 and vibrations of the sprung mass above the suspension system can be suppressed more effectively. As a result, abnormal noises can be suppressed more effectively.
[0028] According to the electric vehicle 20 of this embodiment described above, when the absolute value of the required torque Td* |Td*| is 0 or greater and less than the first value Td1, the gain G is set to 0. When the absolute value of the required torque Td* |Td*| is 1 or greater and less than the second value Td2, the gain G is changed from 0 to 1, increasing when the absolute value of |Td*| is large compared to when it is small. When the absolute value of the required torque Td* |Td*| is 2 or greater, the gain G is set to 1, thereby suppressing abnormal noise.
[0029] In the electric vehicle 20 of the above-described embodiment, when the absolute value of the required torque Td*||Td*| is greater than or equal to 0 and less than the first value Td1, the gain G is set to 0. However, the gain G may be set to a predetermined value that is slightly greater than 0 and less than 1.
[0030] In the electric vehicle 20 of the above-described embodiment, when the absolute value of the required torque Td* |Td*| is greater than or equal to a first value Td1 and less than a second value Td2, the gain G is changed at a second rate from value 0 to value 1 such that it is larger when the absolute value of |Td*| is large compared to when it is small, and when the absolute value of the required torque Td* |Td*| is greater than or equal to a second value Td2, the gain G is set to value 1. However, when the absolute value of the required torque Td* |Td*| is greater than or equal to a first value Td1, the gain G is changed at a second rate from value 0 to value 1 such that it is larger when the absolute value of |Td*| is large compared to when it is small, and after the gain G reaches value 1, the gain G may be maintained at value 1.
[0031] In the electric vehicle 20 of the above-described embodiment, when the absolute value |Td*| of the required torque Td* is greater than or equal to a first value Td1 and less than a second value Td2, the gain G is changed at a second rate from value 0 to value 1 such that it is larger when the absolute value |Td*| is large compared to when it is small. However, it is sufficient to change the gain G from value 0 to value 1 such that it is larger when the absolute value |Td*| is large compared to when it is small, or it may be changed in a curve-like manner.
[0032] In the electric vehicle 20 of the above-described embodiment, the target torque Tdp is set based on the accelerator opening Acc and the vehicle speed V, and the requested torque Td* is set as the torque output to the drive shaft 26 that changes at a first rate from the current torque toward the target torque Tdp. However, the requested torque Td* may also be set based on the accelerator opening Acc and the vehicle speed V such that it is larger when the accelerator opening Acc is large compared to when it is small, and larger when the vehicle speed V is high compared to when it is low.
[0033] In this embodiment, the present disclosure is applied to an electric vehicle 20 equipped with a motor as a power source for driving, but it may also be applied to a hybrid vehicle equipped with an engine and a motor as power sources for driving.
[0034] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, motor 32 corresponds to "motor" and ECU 50 corresponds to "control device".
[0035] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.
[0036] Although the embodiments for implementing this disclosure have been described above, this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]
[0037] This disclosure can be used in industries such as the manufacturing of motor control devices. [Explanation of Symbols]
[0038] 20 Electric vehicle, 22a, 22b Drive wheels, 24 Differential gear, 26 Drive shaft, 32 Motor, 34 Inverter, 36 Battery, 38 Power line, 50 Electronic control unit (ECU), 60 Start switch, 61 Shift lever, 62 Shift sensor, 63 Accelerator pedal, 64 Accelerator sensor, 65 Brake pedal, 66 Brake sensor, 67 Vehicle speed sensor.
Claims
1. A motor control device for an electric vehicle equipped with a motor that outputs power to a drive shaft connected to an axle via a gear mechanism, wherein the motor is controlled so that a torque equal to the sum of the required torque and the effective vibration damping torque obtained by multiplying the required vibration damping torque required for vibration suppression by a gain is output to the drive shaft, When the absolute value of the required torque is less than a first value which is greater than or equal to 0 and greater than 0, the gain is set to a predetermined value which is greater than 0 and less than 1. When the absolute value of the requested torque is greater than or equal to the first value, the gain is changed from a value of 0 or the predetermined value towards a value of 1, such that the gain is greater when the absolute value of the requested torque is large compared to when it is small. Motor control device.
2. A motor control device according to claim 1, When the absolute value of the requested torque is greater than or equal to the first value and less than the second value which is greater than the first value, the gain is changed from a value of 0 or the predetermined value towards a value of 1 such that when the absolute value of the requested torque is large it is larger than when it is small. When the absolute value of the required torque is equal to or greater than the second value, the gain is set to 1. Motor control device.
Citation Information
Patent Citations
Motor control apparatus
JP2015104942A