Motor torque control method and device, motor controller and vehicle

Abstract

The invention provides a motor torque control method and device, a motor controller and a vehicle. The motor torque control method comprises the following steps: acquiring a first actual torque of a left motor and a second actual torque of a right motor, and calculating a balance torque; the balance torque is an absolute value of a difference value between the first actual torque and the second actual torque. And comparing the balance torque with a safety threshold value of the balance torque. And if the balance torque is greater than the safety threshold value, entering a zero torque control mode. And in the zero torque control mode, the first actual torque and the second actual torque are controlled to be gradually decreased to zero. According to the motor torque control method and device, the motor controller and the vehicle, yaw of the vehicle can be effectively avoided.

Description

Technical Field

[0001] The present application relates to the technical field of vehicles, and particularly to a method and device for controlling motor torque, a motor controller, and a vehicle. Background Art

[0002] For a pure electric vehicle driven by dual motors, each drive motor is independently connected to a drive wheel, that is, the left motor is connected to the left wheel, and the right motor is connected to the right wheel. Thus, during the driving torque management of the left and right motors, due to reasons such as control precision or unexpected calculation errors, the output torque difference between the left and right motors is too large, which easily causes the vehicle to yaw during driving. If this abnormality is not suppressed, it may cause a safety accident.

[0003] Therefore, it is necessary to provide an improved method and device for controlling motor torque, a motor controller, and a vehicle to solve the above problems. Summary of the Invention

[0004] The present application provides a method and device for controlling motor torque, a motor controller, and a vehicle that can effectively avoid vehicle yaw.

[0005] The present application discloses a method for controlling motor torque, including:

[0006] Obtaining a first actual torque of a left motor and a second actual torque of a right motor, and calculating a balance torque; the balance torque is the absolute value of the difference between the first actual torque and the second actual torque;

[0007] Comparing the balance torque with a safety threshold of the balance torque;

[0008] If the balance torque is greater than the safety threshold, entering a zero-torque control mode;

[0009] In the zero-torque control mode, controlling the first actual torque and the second actual torque to gradually decrease to zero.

[0010] Further, the method for obtaining the safety threshold includes:

[0011] Obtaining a wheel speed and a steering wheel rotation angle;

[0012] Looking up a table to obtain the safety threshold according to the wheel speed and the steering wheel rotation angle.

[0013] Further, the safety threshold has a negative correlation with the wheel speed; the safety threshold has a negative correlation with the steering wheel rotation angle.

[0014] Further, if the balance torque is greater than the safety threshold, entering the zero-torque control mode includes:

[0015] If the balance torque is greater than the safety threshold, start timing, and record the duration of the timing as the abnormal duration;

[0016] Within the preset verification duration after starting the timing, if the balance torque is not greater than the safety threshold, stop the timing, and clear the abnormal duration;

[0017] When the abnormal duration is equal to the preset verification duration, enter the zero-torque control mode.

[0018] Furthermore, after entering the zero-torque control mode, the method further includes:

[0019] If the balance torque is not greater than the safety threshold, exit the zero-torque control mode, and control the first actual torque and the second actual torque to gradually return to the normal driving state.

[0020] Furthermore, the method further includes:

[0021] In the zero-torque control mode, control the vehicle to issue a warning message; the warning message includes at least one of the following: a specific warning icon lights up on the instrument panel, the vehicle emits a warning sound, and a display component displays a warning message.

[0022] Furthermore, the left motor and the right motor are respectively installed on the left and right sides of the vehicle rear axle; the left motor is used to drive the left rear wheel, and the right motor is used to drive the right rear wheel.

[0023] This application also discloses a motor torque control device, including:

[0024] An acquisition module, configured to obtain the first actual torque of the left motor and the second actual torque of the right motor;

[0025] A calculation module, configured to calculate a balance torque, where the balance torque is the absolute value of the difference between the first actual torque and the second actual torque;

[0026] A judgment module, configured to compare the balance torque with the safety threshold;

[0027] A control module, configured to enter the zero-torque control mode if the balance torque is greater than the safety threshold; and in the zero-torque control mode, control the first actual torque and the second actual torque to gradually decrease to zero.

[0028] This application also discloses a motor controller, including a memory and a processor;

[0029] The memory is used to store a computer program;

[0030] When the processor is used to execute the computer program, the motor torque control method as described above is implemented.

[0031] The present application also discloses a vehicle, including the motor controller as described above.

[0032] The motor torque control method, device, motor controller and vehicle of the present application calculate the balance torque by obtaining the first actual torque of the left motor and the second actual torque of the right motor, and further compare the balance torque with the safety threshold to measure the difference degree of the output torques of the left and right motors, so as to be able to timely detect whether the balance torque exceeds the safe range. At the same time, if the balance torque is greater than the safety threshold, enter the zero torque control mode, and control the first actual torque and the second actual torque to gradually decrease to zero, which can effectively avoid the vehicle yaw risk caused by excessive torque imbalance between the left and right motors, and ensure the driving safety and reliability of the vehicle.

[0033] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this specification. Brief Description of the Drawings

[0034] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments consistent with this specification, and are used together with the specification to explain the principles of this specification.

[0035] Figure 1 is a flowchart of an embodiment of the motor torque control method of the present application.

[0036] Figure 2 is a schematic diagram of the vehicle driving route.

[0037] Figure 3 is a safety threshold table of an embodiment of the motor torque control method of the present application.

[0038] Figure 4 is Figure 1 a flowchart of step S300 in the motor torque control method of

[0039] Figure 5 is a schematic diagram of the motor torque control device of the present application. Detailed Embodiments

[0040] Here, the technical solutions in the embodiments (or "embodiment modes") of the present application will be clearly and completely described in conjunction with the drawings. When the following description involves the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0041] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of this application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of this application described here can be implemented in an order different from those illustrated or described here. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. On the contrary, they are only examples of devices and methods consistent with some aspects of this application as detailed in the appended claims.

[0042] Next, the embodiments of this specification will be described in detail.

[0043] The vehicle includes a front axle and a rear axle, and a pair of wheels are respectively connected to the left and right ends of the front axle and the left and right ends of the rear axle. For a vehicle driven by two motors, two independent motors can be mounted on the front axle or the rear axle of the vehicle to drive the left and right wheels respectively. For a vehicle with two motors mounted on the front axle, the left motor and the right motor respectively output torque to the left front wheel and the right front wheel. For a vehicle with two motors mounted on the rear axle, the left motor and the right motor respectively output torque to the left rear wheel and the right rear wheel.

[0044] As Figure 1 shown, this application provides a method for controlling motor torque, including the following steps:

[0045] Step S100, obtain the first actual torque T Le of the left motor and the second actual torque T Ri of the right motor, and calculate the balance torque T b .

[0046] Under normal driving conditions, after the motor controller is powered on, it will enter the normal torque control mode. In the normal torque control mode, the motor controller will calculate the ideal values (i.e., target torques) of the output torques of the left motor and the right motor, and control the left motor to output the first actual torque T Le , and the right motor to output the second actual torque T Ri . As Figure 2 shown, the rear axle of the vehicle is equipped with two motors, and the left motor and the right motor respectively output torque to the left rear wheel and the right rear wheel, and the output torque of the left motor is greater than that of the right motor. Under normal driving conditions, the traveling trajectory of the whole vehicle should be Figure 2 the acceptable forward trajectory in

[0047] However, in some cases, due to unexpected calculation errors, etc., the calculated target torque may deviate from the actual demand. Or, due to control errors, module failures, etc., the first actual torque T LeWith the second actual torque T Ri There is a deviation from the target torque. These errors may cause the output torques of the left and right motors to be unbalanced. If the difference between the output torque of the left motor and the output torque of the right motor is too large, it will cause abnormal yaw of the whole vehicle, and the traveling trajectory of the whole vehicle will be similar to Figure 2 the dangerous forward trajectory in

[0048] To avoid the above yaw problem, the motor controller will obtain the first actual torque T Le of the left motor and the second actual torque T Ri of the right motor, and calculate the balance torque T b to monitor the difference between the first actual torque T Le and the second actual torque T Ri .

[0049] The balance torque T b is the absolute value of the difference between the first actual torque T Le and the second actual torque T Ri . That is:

[0050] T b = |T Le - T Ri |.

[0051] In some cases, the first actual torque T Le and the second actual torque T Ri can be collected by torque sensors. In some cases, the body state information of the current vehicle can also be obtained through the vehicle's electronic control unit, the body state information can be parsed, the data related to the first actual torque T Le and the second actual torque T Ri can be identified, and then the first actual torque T Le and the second actual torque T Ri can be calculated according to the torque calculation method.

[0052] Step S200, compare the balance torque T b with the safety threshold T thd of the balance torque.

[0053] Generally speaking, the balance torque T b should not exceed a limit value, otherwise it will cause dangerous yaw of the vehicle due to the excessive balance torque T b . This limit value is the safety threshold T thd of the balance torque. The safety threshold T thd is related to the current wheel speed of the vehicle and the rotation angle of the steering wheel. In this application, the wheel speed refers to the average value of the rotation speeds of the left and right motors.

[0054] Specifically, in this embodiment, the safety threshold T thd is obtained by the following method:

[0055] Obtain the wheel speed and the steering wheel rotation angle.

[0056] Look up the table according to the wheel speed and the steering wheel rotation angle to obtain the safety threshold T thd .

[0057] In some cases, the wheel speed of the vehicle can be calculated after being collected by wheel speed sensors on both sides or motor speed sensors, and the steering wheel rotation angle can be collected by a steering wheel angle sensor. In some cases, the vehicle body state information of the current vehicle can also be obtained through the vehicle's electronic control unit, the body state information can be analyzed, the data related to the wheel speed and the steering wheel rotation angle can be identified, and then the current wheel speed and the steering wheel rotation angle of the vehicle can be obtained according to these data.

[0058] The safety threshold T thd is determined by using the look-up table method. The mapping relationship between the safety threshold T thd and the wheel speed and the steering wheel rotation angle is confirmed in advance, and a table is established. The data in the table can be obtained through vehicle dynamic simulation and / or real vehicle tests.

[0059] Figure 3 shows a relationship table between the safety threshold T thd and the wheel speed and the steering wheel rotation angle in an embodiment. It can be seen from the table that under different wheel speeds and different steering wheel rotation angles, the value of the safety threshold T thd is also different. The safety threshold T thd is overall negatively correlated with the actual vehicle speed. As the vehicle speed increases, the requirement for the torque balance of the left and right motors is higher. The safety threshold T thd is overall negatively correlated with the steering wheel rotation angle. When the steering wheel rotation angle is large, the vehicle may be in a special driving state such as turning. At this time, the requirement for the torque balance of the left and right motors is also higher. Reducing the safety threshold when the requirement for the torque balance of the left and right motors is higher helps to better control the motor torque and improve the handling performance and safety of the vehicle.

[0060] Figure 3 The table only shows the corresponding safety threshold T thd under some specific wheel speeds and specific steering wheel rotation angles. During actual operation, the safety threshold T thd corresponding to other wheel speeds and steering wheel rotation angles can be obtained through difference calculation or other conversion relationships.

[0061] In some cases, the safety threshold T thdIt can also be obtained through other means. For example, a vehicle dynamics model is established, and the safety threshold T is obtained by derivation according to the model. thd ; Establish the safety threshold T thd calculation formula, and substitute the data collected during the actual operation of the vehicle into the formula to calculate and obtain the safety threshold T thd , and so on. This application does not make any limitations in this regard.

[0062] Step S300, if the balance torque T b is greater than the safety threshold T thd , enter the zero-torque control mode.

[0063] When it is monitored that the balance torque T b is greater than the safety threshold T thd , it indicates that the actual torque difference between the left and right motors in the current state has exceeded the safety limit value, and there is a possibility of causing dangerous yaw of the vehicle. It is necessary to immediately take protective measures, that is, exit the normal torque control mode and enter the zero-torque control mode.

[0064] If the balance torque T b is not greater than the safety threshold T thd , continue to operate in the normal torque control mode, and continuously compare the magnitude of the balance torque T b with the safety threshold T thd .

[0065] Further, to improve the reliability of the monitoring results, the motor torque control method of this application has a delay verification function. As Figure 4 shown, step S300 further includes the following steps:

[0066] Step S301, if the balance torque T b is greater than the safety threshold T thd , start timing, and record the duration of the timing as the abnormal duration t.

[0067] Step S302, within the preset verification duration t dly when timing is started, if the balance torque T b is not greater than the safety threshold T thd , stop timing, and clear the abnormal duration t to zero.

[0068] Step S303, when the abnormal duration t is equal to the preset verification duration t dly , enter the zero-torque control mode.

[0069] That is to say, only when within the preset verification duration t dly , the balance torque T b continuously remains greater than the safety threshold T thd, it will be determined as an abnormal state and enter the zero-torque control mode. If within the preset verification duration t dly after starting the timing, the balance torque T b changes again to not greater than the safety threshold T thd , the timing is stopped, the abnormal duration t is cleared, and the timing restarts when the balance torque T b is detected to be greater than the safety threshold T thd next time.

[0070] By setting the preset verification duration t dly before entering the zero-torque control mode for delay verification, it can effectively prevent misjudgment caused by abnormal fluctuations of the motor in a short time, ensure the authenticity and accuracy of the abnormal determination of the balance torque T b , and avoid frequent switching of protection operations, thereby improving the working efficiency and service life of the motor.

[0071] Step S400: In the zero-torque control mode, control the first actual torque T Le and the second actual torque T Ri to gradually decrease to zero.

[0072] After entering the zero-torque control mode, the motor controller will control the first actual torque T Le and the second actual torque T Ri to gradually decrease until the first actual torque T Le and the second actual torque T Ri are zero, finally achieving the output torque balance between the left motor and the right motor. After the first actual torque T Le and the second actual torque T Ri decrease to zero, the left motor and the right motor will no longer transmit torque to the wheels, which can avoid further deterioration of vehicle yaw and ultimately ensure the safety of the whole vehicle.

[0073] The first actual torque T Le and the second actual torque T Ri can be decreased linearly, with the torque gradually decreasing at a fixed rate until it reaches zero. Or it can be decreased in a gradient manner, dividing the torque decrease process into multiple stages, each stage using a different slope.

[0074] The decrease process of the first actual torque T Le and the second actual torque T Ri can be dynamically adjusted according to the real-time data of vehicle driving (such as vehicle speed, motor speed, motor temperature, load, etc.). For example, in the case of overheating of the motor or too high vehicle speed, the first actual torque T Le and the second actual torque T RiQuickly decrease to ensure driving safety. When the motor temperature is relatively low or the vehicle speed is relatively low, the first actual torque T Le and the second actual torque T Ri are slowly decreased to ensure smooth driving, while reducing the mechanical wear of the motor and extending the service life of the equipment.

[0075] In the zero-torque control mode, the vehicle occupants inside the vehicle or relevant personnel outside the vehicle can also be alerted in other ways. For example, the vehicle is controlled to emit a warning message. The warning message includes at least one of a specific warning icon lighting up on the instrument panel, the vehicle emitting a warning sound, and the display component displaying a warning message, so as to issue a visual warning and / or an audible warning to the driver or other vehicle occupants. In some cases, the vehicle lights can also be controlled to emit a warning message to provide a warning to the surrounding personnel outside the vehicle.

[0076] The motor controller can also generate relevant fault codes in the zero-torque control mode and transmit the fault codes to the relevant control units of the vehicle in real time through the CAN bus, realizing accurate recording and transmission of fault information through a standardized diagnostic protocol, and improving the reliability of the vehicle.

[0077] Furthermore, after entering the zero-torque control mode, the motor torque control method further includes the following steps:

[0078] If the balanced torque T b is not greater than the safety threshold T thd , exit the zero-torque control mode, and control the first actual torque T Le and the second actual torque T Ri to gradually return to the normal driving state.

[0079] That is to say, in the zero-torque control mode, the motor controller continuously monitors the balanced torque T b . If it is monitored that the balanced torque T b is not greater than the safety threshold T thd , it means that the actual torques output by the motors on both sides have returned to normal at this time, and there is no need to further decrease the actual torque. The motor controller exits the zero-torque control mode and returns to the normal torque control mode, controlling the first actual torque T Le and the second actual torque T Ri to gradually return to the normal driving state. In this way, the normal driving performance of the vehicle can be restored in time after the balanced torque T b returns to normal, improving the use efficiency of the vehicle and the user experience. The recovery of the first actual torque T Le and the second actual torque T Ri is progressive, which can effectively avoid the vehicle jerk caused by a sudden increase in torque.

[0080] Similarly, before exiting the zero-torque control mode, a delay verification function can also be introduced. Only when the balanced torque T b is not greater than the safety threshold T thd for a certain period of time, the zero-torque control mode is exited to prevent repeated switching caused by instantaneous interference.

[0081] In this embodiment, the left motor and the right motor are respectively installed on the left and right sides of the vehicle rear axle. The left motor is used to drive the left rear wheel, and the right motor is used to drive the right rear wheel. This is because the yaw sensitivity of the dual motors on the rear axle is relatively high, and the imbalance of the output torques of the two motors has a relatively serious impact on the yaw of the whole vehicle, and more strict torque balance control is required. By arranging the dual motors on the vehicle rear axle and applying the motor torque control method of the present application, the stability and controllability of vehicle driving can be effectively improved. In some cases, the left motor and the right motor can also be respectively installed on the left and right sides of the vehicle front axle.

[0082] In this embodiment, the acquisition of the first actual torque T Le and the second actual torque T Ri , the calculation of the balanced torque T b , and the comparison of the size between the balanced torque T b and the safety threshold T thd are all carried out in real time, which can realize the timely response to the abnormal balanced torque and quickly intervene before the vehicle has abnormal yaw.

[0083] As Figure 5 shown, the present application also provides a motor torque control device, including:

[0084] An acquisition module, configured to acquire the first actual torque of the left motor and the second actual torque of the right motor.

[0085] A calculation module, configured to calculate the balanced torque, where the balanced torque is the absolute value of the difference between the first actual torque and the second actual torque.

[0086] A judgment module, configured to compare the size of the balanced torque with the safety threshold.

[0087] A control module, configured to enter the zero-torque control mode if the balanced torque is greater than the safety threshold; and in the zero-torque control mode, control the first actual torque and the second actual torque to gradually decrease to zero.

[0088] The present application also provides a motor controller, including a memory and a processor.

[0089] The memory is used to store a computer program.

[0090] The processor is configured to implement the motor torque control method as described above when executing the computer program.

[0091] The present application also provides a vehicle, including the motor controller as described above.

[0092] The motor torque control method, device, motor controller and vehicle of the present application calculate the balance torque by obtaining the first actual torque of the left motor and the second actual torque of the right motor, and further compare the balance torque with the safety threshold to measure the difference degree of the output torques of the left and right motors, so as to timely detect whether the balance torque exceeds the safety range. At the same time, if the balance torque is greater than the safety threshold, enter the zero torque control mode, and control the first actual torque and the second actual torque to gradually decrease to zero, which can effectively avoid the vehicle yaw hazard caused by excessive torque imbalance between the left and right motors, and ensure the driving safety and reliability of the vehicle.

[0093] It should be noted that the technical solutions or technical features described in the above embodiments can be combined or supplemented with each other without conflict. The scope of protection of the present application is not limited to the precise structures described in the above embodiments and shown in the drawings; any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for controlling the torque of an electric motor, characterized in that, Including: Obtain the first actual torque of the left motor and the second actual torque of the right motor, and calculate the balance torque; The balance torque is the absolute value of the difference between the first actual torque and the second actual torque; Compare the balance torque with the safety threshold of the balance torque; If the balance torque is greater than the safety threshold, enter the zero-torque control mode; In the zero-torque control mode, control the first actual torque and the second actual torque to gradually decrease to zero.

2. The motor torque control method according to claim 1, characterized in that, The method for obtaining the safety threshold includes: Obtain the wheel speed and the steering wheel rotation angle; According to the wheel speed and the steering wheel rotation angle, look up a table to obtain the safety threshold.

3. The motor torque control method according to claim 2, wherein, The safety threshold has a negative correlation with the wheel speed; the safety threshold has a negative correlation with the steering wheel rotation angle.

4. The motor torque control method according to claim 1, wherein If the balance torque is greater than the safety threshold, entering the zero-torque control mode includes: If the balance torque is greater than the safety threshold, start timing, and record the duration of the timing as the abnormal duration; Within the preset verification duration after starting timing, if the balance torque is not greater than the safety threshold, stop timing, and clear the abnormal duration; When the abnormal duration is equal to the preset verification duration, enter the zero-torque control mode.

5. The motor torque control method according to claim 1, characterized in that, After entering the zero-torque control mode, the method further includes: If the balance torque is not greater than the safety threshold, exit the zero-torque control mode, and control the first actual torque and the second actual torque to gradually return to the normal driving state.

6. The motor torque control method according to claim 1, wherein The method further includes: In the zero-torque control mode, control the vehicle to issue a warning message; the warning message includes at least one of the following: a specific warning icon lights up on the dashboard, the vehicle emits a warning sound, and a display component displays a warning message.

7. The motor torque control method according to claim 1, characterized in that The left motor and the right motor are respectively installed on the left and right sides of the vehicle rear axle; the left motor is used to drive the left rear wheel, and the right motor is used to drive the right rear wheel.

8. A motor torque control device, characterized in that Including: A collection module for obtaining the first actual torque of the left motor and the second actual torque of the right motor; A calculation module for calculating the balance torque, where the balance torque is the absolute value of the difference between the first actual torque and the second actual torque; A judgment module for comparing the balance torque with the safety threshold of the balance torque; A control module for entering the zero-torque control mode if the balance torque is greater than the safety threshold; And in the zero-torque control mode, control the first actual torque and the second actual torque to gradually decrease to zero.

9. A motor controller, characterized in that, Including a memory and a processor; The memory is used to store a computer program; When the processor executes the computer program, it implements the motor torque control method according to any one of claims 1 to 7.

10. A vehicle, characterized in that, Including the motor controller according to claim 9.

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