Dual-motor controller, control method and electric vehicle

Abstract

A dual-motor controller, relating to the field of new energy vehicles, and applicable to pure electric vehicles and hybrid vehicles. The dual-motor controller is used for suppressing yaw motion of an electric vehicle when traveling on a µ-split road surface, and used for controlling two drive motors to output torques to respectively drive two wheels on the same axle of the electric vehicle. The dual-motor controller is specifically user for: at a first moment, when the slip ratios of the two wheels are both less than a preset slip rate, controlling the two drive motors to output torques indicated by a torque signal; and at a second moment following the first moment, when the slip ratio of at least one of the two wheels is greater than the preset slip ratio, actively controlling the two drive motors to simultaneously lower torque outputs. The dual-motor controller can quickly regulate the torques of the motors, so that the torques of the left and right wheels are equal, thereby suppressing vehicle yaw and improving vehicle safety. The present invention also relates to an electric vehicle control method and an electric vehicle.

Description

Dual-motor controller, control method and electric vehicle

[0001] This application claims priority to Chinese Patent Application No. 202411896149.2, filed on December 19, 2024, entitled "Dual Motor Controller, Control Method and Electric Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of new energy vehicles, and more specifically, to a dual-motor controller, a control method, and an electric vehicle. Background Technology

[0003] A split-surface road surface refers to a road surface where the coefficients of friction on the left and right sides of a vehicle are different. When a vehicle suddenly enters a split-surface road surface while traveling straight or starts on a split-surface road surface, the tire on the lower friction side may lose traction earlier than the tire on the higher friction side, causing the vehicle to yaw and affecting vehicle safety.

[0004] Traditional chassis control typically relies on the electronic stability program (ESP), which uses wheel speed sensors to detect vehicle slippage and then applies torque control accordingly. However, due to the low accuracy of wheel speed sensors, the low frequency of the vehicle control loop, and the long transmission time, the entire control system experiences a significant delay. This can lead to situations where, when the vehicle suddenly enters or starts on a split-level road surface, the wheels cannot reduce torque in time, causing the low-touch tires to exceed the road surface adhesion limit, resulting in significant vehicle yaw and compromising driving safety.

[0005] Therefore, how to suppress the lateral sway of vehicles on opposite sides of the road is a problem that needs to be solved. Summary of the Invention

[0006] This application provides a dual-motor controller, control method, and electric vehicle. When the electric vehicle enters or starts from a split road surface, if wheel slippage occurs, the drive system quickly adjusts the output torque to reduce the torque of both the left and right wheels, thereby suppressing vehicle yaw and improving overall vehicle safety.

[0007] In a first aspect, this application provides a dual-motor controller for suppressing yaw in an electric vehicle traveling on a split-level road. The dual-motor controller controls the output torque of two drive motors to drive the two coaxial wheels of the electric vehicle respectively. Specifically, at a first moment, when the slip ratios of both wheels are less than a preset slip ratio, the dual-motor controller controls the torque output of the two drive motors to the torque indicated by the torque signals. At a second moment, after the first moment, when the slip ratio of at least one of the two wheels is greater than the preset slip ratio, the controller actively controls both drive motors to simultaneously reduce their torque output.

[0008] This dual-motor controller is suitable for electric or hybrid vehicles, which can have a distributed or centralized motor architecture with multiple drive motors. The drive motors can be wheel-side motors or in-wheel motors, and each drive motor can independently drive one wheel of the vehicle. The dual-motor controller can output three-phase AC power to two drive motors respectively, thereby controlling the output torque of each drive motor. The two drive motors drive two coaxial wheels. These coaxial wheels can be the two front wheels or the two rear wheels of an electric vehicle.

[0009] A drive motor consists of a stator winding and a rotor. A dual-motor controller controls the output torque of the drive motor by outputting alternating current to the three-phase stator winding. By adjusting the magnitude and phase of the input stator winding current, the dual-motor controller changes the strength and direction of the stator magnetic field, thereby altering the interaction force between the stator and rotor, and thus controlling the drive motor's output torque (positive or negative). Reverse torque can also be called negative torque. During forward motion of an electric vehicle, positive torque drives the vehicle, and reverse torque brakes it. During reverse motion, positive torque brakes the vehicle, and reverse torque drives it. The dual-motor controller can change the phase of the three-phase current output to the drive motor, causing the rotor to cut the magnetic field generated by the stator winding. The rotor's kinetic energy is converted into electrical energy and input into the power battery, at which point the drive motor outputs reverse torque. By changing the magnitude of the three-phase current output to the motor, the dual-motor controller can increase or decrease the motor's output torque (positive or negative). It should be understood that this application uses the example of an electric vehicle driving forward. A similar description can be used in the scenario of an electric vehicle reversing. The direction of the torque output by the drive motor can be modified accordingly, but the function of the torque should remain consistent.

[0010] It should be understood that reducing torque output in this application refers to reducing the absolute value of the output torque. When the dual-motor controller controls the drive motor to output positive torque, the torque value is greater than zero, and reducing torque in this case means reducing the torque value. When the dual-motor controller controls the drive motor to output reverse torque, the torque value of the reverse torque is less than zero, and reducing torque in this case means increasing the torque value and decreasing the absolute value of the reverse torque.

[0011] At the initial moment, the slip ratios of both wheels are less than the preset slip ratio, and neither wheel slips. During the operation of the electric vehicle, the dual-motor controller receives torque signals from the vehicle controller, which indicate the torque output by the two drive motors. When neither wheel slips, the dual-motor controller controls the torque output by the two drive motors as indicated by the torque signals. By controlling the torque output by the drive motors when the wheels are not slipping, there is no need to reduce torque to suppress slip ratio, thus improving the vehicle's driving performance and power.

[0012] At the second moment after the first moment, if the slip ratio of at least one of the two wheels exceeds the preset slip ratio, at least one wheel will slip, and the torque output needs to be reduced. When an electric vehicle starts on a split-type road or passes through a split-type road while driving, due to the different road surface adhesion coefficients of the left and right wheels of the electric vehicle, the road surface adhesion coefficient on one side is lower, and when the wheel torque exceeds the maximum road surface adhesion, the wheel will slip.

[0013] A slip ratio greater than a preset slip ratio for at least one of the two wheels includes situations where one wheel's slip ratio is greater than the preset slip ratio, while the other wheel's slip ratio is less than or equal to the preset slip ratio. In this case, one wheel slips while the other wheel does not. A slip ratio greater than a preset slip ratio for at least one of the two wheels also includes situations where both wheels' slip ratios are greater than the preset slip ratio. In this case, both wheels slip.

[0014] For electric vehicles with distributed drive motors, when the vehicle enters or starts on a split-path surface in a driving mode, the dual-motor controller controls both drive motors to output positive torque. When one wheel slips, the drive motor driving that wheel needs to quickly reduce torque; otherwise, the wheel on the low-traction side will slip, causing the vehicle to lose control. Simultaneously, the other drive motor also needs to be controlled to quickly reduce torque in coordination; otherwise, the traction force on the left and right wheels will be unequal, with the traction force on the high-traction side being greater than that on the low-traction side, causing the vehicle to yaw towards the low-traction side. When the vehicle enters or starts on a split-path surface in a feedback mode, the dual-motor controller controls the drive motors to output reverse torque. When one wheel slips, the drive motor driving that wheel needs to quickly reduce torque, and the other drive motor also needs to be controlled to quickly reduce torque in coordination; otherwise, the braking force on the high-traction side will be greater than that on the low-traction side, causing the vehicle to yaw towards the high-traction side. By simultaneously and quickly reducing the torque on both wheels, vehicle yaw is suppressed.

[0015] According to the solution in this application, in scenarios where an electric vehicle is driving straight onto a split road or starting on a split road, by rapidly sensing the road surface adhesion and rapidly adjusting the torque, the torque of the left and right wheels of the vehicle is reduced simultaneously to prevent slippage, suppress vehicle yaw, and improve driving safety.

[0016] In conjunction with the first aspect, in some implementations of the first aspect, the road surface that the two wheels are in contact with at the first moment is a uniform road surface, and the road surface that the two wheels are in contact with at the second moment is a split road surface. The difference in the adhesion coefficients of the two wheels on the uniform road surface is less than or equal to a preset difference, and the difference in the adhesion coefficients of the two wheels on the split road surface is greater than the preset difference.

[0017] At the first moment, the electric vehicle's wheels are in contact with a uniform road surface. The road surface adhesion coefficients on both sides of the electric vehicle are uniform, and the difference in adhesion coefficients between the left and right wheels on the road surface is less than or equal to a preset difference. The slip rates of the left and right wheels will be similar.

[0018] At the second moment, the electric vehicle's wheels are in contact with a split road surface. The coefficients of adhesion on the left and right sides of the road are different, and the difference in the coefficients of adhesion between the left and right wheels is greater than a preset difference. Consequently, the slip rates of the left and right wheels may differ significantly. Specifically, the dual-motor controller is used during the electric vehicle's driving or starting process to actively control both drive motors to simultaneously reduce torque output when the slip rate of one wheel exceeds a preset slip rate and the slip rate of the other wheel is also greater.

[0019] When an electric vehicle enters or starts on a split-level road surface, the coefficients of adhesion on both sides of the road are unequal, resulting in different slip rates for the wheels on both sides. One wheel may slip more than a preset slip rate, causing slippage, while the other wheel may not slip. In this case, for the slipping wheel, the drive motor driving that wheel needs to reduce torque to suppress slippage. For the non-slipping wheel, slippage suppression is not necessary, but the drive torque needs to be reduced simultaneously to suppress yaw of the electric vehicle.

[0020] According to the solution in this application, when an electric vehicle is driving straight onto a road with two parallel tracks or starting on a road with two parallel tracks, if one wheel slips, the torque of the left and right wheels of the electric vehicle is reduced simultaneously. This prevents wheel slippage, suppresses vehicle yaw, and improves driving safety.

[0021] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is also used at a second moment to actively control the two drive motors to simultaneously reduce their torque output so that the torque output by the two drive motors is less than the torque indicated by the torque signal.

[0022] At the second moment, if the slip ratio of at least one of the two wheels exceeds the preset slip ratio, at least one wheel slips. At this point, the torque output needs to be reduced, and the torque output by the drive motor is less than the torque indicated by the torque signal. The torque output by the drive motor no longer changes with the torque indicated by the torque signal, but is determined by the closed-loop control within the dual-motor controller.

[0023] According to the solution in this application, when the wheels slip, the dual-motor controller quickly adjusts the torque, responds rapidly, reduces signal transmission time, and improves vehicle safety.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is also used to: at a third moment after the second moment, when the slip rates of both wheels are less than or equal to a preset slip rate, control the torque output by the two drive motors to stop decreasing.

[0025] At the third moment, during the process of reducing torque, the slip ratio of both wheels is less than or equal to the preset slip ratio, the slipping characteristics disappear, and the wheels on both sides no longer slip. At this time, the dual motor controller controls the torque output of the two drive motors to stop decreasing.

[0026] According to the solution in this application, when the slippage characteristics of the electric vehicle disappear, the drive motor is controlled to stop reducing torque output, thereby preventing the electric vehicle from losing power and improving the vehicle's handling and safety.

[0027] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is also used to control the torque output by the two drive motors to increase to the torque indicated by the torque signal after the third moment.

[0028] At the third moment, during the torque reduction process, the slip ratios of both wheels are less than or equal to the preset slip ratio, the slippage characteristics disappear, and the wheels on both sides no longer slip. At this time, the dual-motor controller stops reducing the torque output of the two drive motors and then increases the torque output of the two drive motors again. The dual-motor controller can respond to the torque changes indicated by the torque signal again.

[0029] According to the solution in this application, when the slippage characteristics of the electric vehicle disappear, the drive motor is recontrolled to increase the output torque, restore the traction of the electric vehicle, and improve the vehicle's handling and safety.

[0030] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is also used to actively control the two drive motors to reduce torque output when, at a second moment, the slip rate of at least one of the two wheels is greater than a preset slip rate and the opening of the accelerator pedal of the electric vehicle increases.

[0031] The accelerator pedal in this application can also be referred to as the power pedal or throttle pedal. The opening degree of the accelerator pedal indicates the amount of driving force required by the driver. The larger the opening degree of the accelerator pedal, the greater the driver's demand for driving force, and the greater the torque required from the drive motor. When the electric vehicle is not slipping, the dual-motor controller can control the drive motor to output the torque indicated by the accelerator pedal opening degree. The larger the accelerator pedal opening degree, the greater the torque output by the drive motor; the smaller the accelerator pedal opening degree, the smaller the torque output by the drive motor. The dual-motor controller controls the torque output by the drive motor to change with the change in the accelerator pedal opening degree.

[0032] During normal operation of the electric vehicle, the dual-motor controller responds to the torque signal sent by the vehicle controller to control the drive motor to output the torque indicated by the accelerator pedal. When the electric vehicle suddenly enters a split-level road or starts on a split-level road, if the torque corresponding to the accelerator pedal opening indicated by the torque signal sent by the vehicle controller is greater than the maximum traction of the tires on the split-level road, the dual-motor controller can quickly adjust the torque. At this time, the torque output by the drive motor does not change with the torque command or the opening of the accelerator pedal.

[0033] At the second moment, even if the driver presses the accelerator pedal and the opening of the accelerator pedal increases, because the slip ratio of at least one of the two wheels is greater than the preset slip ratio, there is a slip phenomenon. Therefore, it cannot respond to the increase in the opening of the accelerator pedal. Instead, the dual-motor controller performs internal control and actively controls the two drive motors to reduce the output torque.

[0034] According to the solution in this application, when the wheels slip, the dual-motor controller quickly adjusts the torque internally, which does not change with the opening of the accelerator pedal. This rapid response reduces signal transmission time and improves vehicle safety.

[0035] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is specifically used to actively control the two drive motors to simultaneously reduce torque output when, at a second moment, the change in the rotational speed of at least one of the two drive motors within a preset time period is greater than a preset value.

[0036] When an electric vehicle starts or traverses a split-level road surface, the different coefficients of friction between the left and right wheels cause slippage. One side has a lower coefficient of friction, and when the wheel torque exceeds the maximum friction, the wheel spins, causing a sudden increase or decrease in wheel speed. This change in wheel speed is quickly reflected in the drive motor's rotational speed. The drive motor's rotational speed can be detected by a resolver sensor. The resolver sensor accurately detects the position, direction, and speed of the drive motor rotor, monitoring and extracting the drive motor's rotational speed. It has a high sampling rate and is directly connected to the dual-motor controller, resulting in short signal transmission time and higher stability. When the change in the rotational speed of one drive motor indicated by the resolver sensor exceeds a preset value within a preset time period, the rotational speed of the wheel driven by that motor changes abruptly. When the drive motor outputs positive torque, the change within the preset time period increases; when the drive motor outputs reverse torque, the change within the preset time period decreases.

[0037] The dual-motor controller determines whether the wheel driven by the drive motor is slipping based on the resolver signal of the drive motor. If the wheel slips, the controller needs to control the drive motor to reduce its output torque. At the same time, the dual-motor controller also needs to determine whether the wheel on the opposite side is slipping. If the wheel on the opposite side is slipping, the drive motor on that side will also reduce its output torque.

[0038] According to the solution in this application, when both wheels slip, the vehicle yaw is suppressed by quickly sensing the road surface adhesion and quickly adjusting the torque, thus preventing slippage on both sides and improving vehicle handling and safety.

[0039] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is also used to control the torque output of the two drive motors to be equal between the second and third time points.

[0040] Between the second and third time points, to suppress yaw in the electric vehicle, the drive torque of the left and right wheels should remain equal. Simultaneously, to suppress wheel slippage, the reduction in output torque of the drive motor should be greater on the side with the larger reduction. The greater the wheel slip ratio, the greater the torque reduction required from the drive motor. The dual-motor controller can determine which wheel has a greater slip ratio based on the change in the rotational speed of the two drive motors within a preset time period.

[0041] According to the solution of this application, when both wheels slip, by quickly sensing the road surface adhesion and quickly adjusting the torque, the torque of the left and right wheels of the vehicle is kept equal and equal to the torque output by the drive motor on the low-adhesion side, which suppresses vehicle yaw and prevents slippage on both sides, thereby improving vehicle handling and safety.

[0042] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is specifically used to control the torque output of the two drive motors to decrease at a preset rate of change or in a stepwise manner between the second and third time points.

[0043] Between the second and third time points, during the process of controlling the drive motor to reduce torque, the dual-motor controller can control the torque to decrease in a step-like manner with a certain gradient, or decrease it according to a preset rate of change. This preset rate of change can be obtained through vehicle calibration or can be a preset value.

[0044] According to the solution in this application, when the wheels slip, the dual-motor controller controls the reduction of the drive motor torque output at a fixed rate of change or in a stepped manner, which can effectively suppress slippage and reduce jerking, suppress vehicle yaw, and improve vehicle safety and comfort.

[0045] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is specifically used to control the reduction of the output torque of the two drive motors by a greater change in the rotational speed of at least one drive motor within a preset time period between the second and third time periods.

[0046] The dual-motor controller can obtain the rotational speed of the drive motor through the resolver signal from the resolver sensor. The rate of change of the drive motor speed or the change in speed within a preset time period can reflect the change in the adhesion between the wheel and the road surface to a certain extent. When the rate of change of the drive motor speed is greater or the change in speed within the preset time period is greater, it indicates that the road adhesion has decreased significantly. In this case, in order to control the wheel from slipping, it is necessary to reduce the torque output of the drive motor more.

[0047] According to the solution in this application, the torque of the drive motor is controlled by rapidly sensing the changes in the adhesion of the opposite road surface through the speed change of the drive motor, so as to keep the torque of the left and right wheels of the vehicle equal, suppress vehicle yaw, and improve driving safety.

[0048] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is specifically used between the second and third time points, such that the smaller the driving torque of at least one wheel, the greater the reduction in the output torque of the two drive motors.

[0049] The dual-motor controller can calculate the actual output torque of the drive motor from the actual output current, and the actual output torque of the drive motor is directly proportional to the road surface adhesion. Therefore, the smaller the output torque of the drive motor, the smaller the maximum road surface adhesion, and in order to prevent the wheels from slipping, it is necessary to reduce the output torque of the drive motor even more.

[0050] According to the solution in this application, the torque of the drive motor is controlled by quickly sensing the changes in the adhesion of the opposite road surface through the actual output torque of the drive motor, so as to keep the torque of the left and right wheels of the vehicle equal, suppress vehicle yaw, and improve driving safety.

[0051] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is specifically used between the second and third time points, such that the greater the difference between the slip rate of at least one wheel and the preset slip rate, the greater the reduction in the output torque of the two drive motors.

[0052] The dual-motor controller obtains the rotational speed of the drive motor through the resolver signal from the resolver sensor. The angular velocity of the wheels can be calculated using the drive motor speed and the transmission ratio of the electric vehicle. Combining this with the wheel radius and the speed of the electric vehicle, the slip ratio of each wheel can be obtained. In this application, slip ratio can refer to slip displacement ratio. The wheels of the electric vehicle achieve maximum adhesion at a preset slip ratio; therefore, by controlling the wheel slip ratio, the electric vehicle can fully utilize the road surface adhesion.

[0053] According to the solution in this application, the torque of the drive motor is controlled by rapidly sensing the changes in the adhesion of the opposite road surface through the changes in the wheel slip ratio of the electric vehicle, so as to keep the torque of the left and right wheels of the vehicle equal, suppress vehicle yaw, and improve driving safety.

[0054] In conjunction with the first aspect, in some implementations of the first aspect, the dual-motor controller is specifically used such that, between the second and third time points, the absolute value of the torque output by the two drive motors is less than or equal to the absolute value of the torque indicated by the torque signal, and the direction of the torque output by the two drive motors is the same as the direction of the torque indicated by the torque signal.

[0055] In the process of controlling the torque reduction of the drive motor, the dual-motor controller needs to limit the final output torque of the drive motor. The absolute maximum value of the final output torque of the drive motor cannot exceed the torque indicated by the torque signal sent by the vehicle controller, and the final output torque is not allowed to reverse.

[0056] According to the solution in this application, in scenarios where an electric vehicle is driving straight onto a split road or starting on a split road, by rapidly sensing the road surface adhesion and rapidly adjusting the torque, the torque of the left and right wheels of the vehicle is kept equal, and the final torque is limited to not exceeding the torque given by the current vehicle controller, and torque reversal is not allowed, thereby suppressing vehicle yaw and improving driving safety.

[0057] Secondly, this application provides a control method for an electric vehicle to suppress yaw during operation on a split-road surface. The control method includes: at a first moment, when the slip rates of both coaxial wheels of the electric vehicle are less than a preset slip rate, controlling the driving torque of the two wheels to the torque indicated by the accelerator pedal opening of the electric vehicle; and at a second moment after the first moment, when the slip rate of at least one of the two wheels is greater than the preset slip rate, actively controlling the driving torque of the two wheels to decrease.

[0058] In one implementation, the electric vehicle includes multiple motor controllers and multiple drive motors. One motor controller controls the output torque of one drive motor to drive or brake one wheel of the electric vehicle. Another motor controller also controls the output torque of another drive motor to drive or brake another wheel of the electric vehicle. The one wheel and the other wheel are either the two front wheels or the two rear wheels of the electric vehicle.

[0059] A motor controller is used to control one drive motor to reduce its output torque during the driving or starting process of an electric vehicle, in response to a change in the speed of one drive motor within a preset time period exceeding a preset value. When the change in speed of one drive motor within a preset time period is less than or equal to a preset value, and the change in speed of another drive motor within a preset time period is greater than a preset value, the controller controls the output torque of one drive motor to be reduced to be equal to the output torque of the other drive motor.

[0060] The motor controller uses resolver signals to determine if the wheels driven by the controlled drive motor are slipping. If the wheels are not slipping, the controller outputs the torque indicated by the torque signal to the drive motor. If wheels are slipping, the controller reduces the torque output of the drive motor. If the opposite wheel is slipping, the controller outputs the same torque as the reduced torque of the opposite drive motor.

[0061] The motor controller can determine whether the opposite wheel is slipping in several ways. For example, the motor controller can be connected to the motor controller controlling the opposite drive motor and obtain changes in the output torque of the opposite drive motor from the opposite drive motor's motor controller. As another example, the motor controller can be connected to the motor controller controlling the opposite drive motor and obtain the slip ratio of the opposite wheel from the opposite drive motor's motor controller, and determine the value of reducing the drive motor's torque based on the slip ratios of both wheels. Yet another example, the motor controller can be connected to the opposite drive motor and determine whether the opposite wheel is slipping based on a resolver signal.

[0062] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: at a third time point after the second time point, when the slip ratios of both wheels are less than or equal to a preset slip ratio, controlling the driving torque of the two wheels to stop decreasing. After the third time point, controlling the driving torque of the two wheels to increase to the torque indicated by the accelerator pedal opening.

[0063] In conjunction with the second aspect, in some implementations of the second aspect, the control method specifically includes: controlling the driving torque of the two wheels to be equal between the second and third time points.

[0064] A motor controller is used to control one drive motor to reduce its output torque during the driving or starting process of an electric vehicle. This is done when the change in speed of one drive motor within a preset time period exceeds a preset value, and the change in speed of another drive motor within the same preset time period exceeds a preset value but is less than or equal to the change in speed of the first drive motor within the same preset time period. Conversely, if the change in speed of one drive motor within a preset time period exceeds a preset value, and the change in speed of another drive motor within the same preset time period exceeds both the preset values ​​and the change in speed of the first drive motor within the same preset time period, the controller controls one drive motor to reduce its output torque to match that of the other drive motor.

[0065] A motor controller is also used to control a drive motor to stop reducing output torque and increase output torque in response to the change in the speed of a drive motor within a preset time period, as indicated by the resolver sensor of the electric vehicle, decreasing to less than or equal to a preset value.

[0066] A motor controller is also used to control one drive motor to reduce its output torque to equal that of another drive motor. When the change in the speed of the other drive motor within a preset time period decreases to less than or equal to a preset value, the controller stops reducing the output torque of one drive motor and increases its output torque. When the slippage characteristics of the opposite wheel disappear and the electric vehicle no longer slips, the motor controller can control the output torque of the drive motor to increase again.

[0067] Thirdly, this application provides an electric vehicle comprising a dual-motor controller, a vehicle controller, and an accelerator pedal as described in the first aspect and its various implementations. The vehicle controller sends a torque signal to the motor controller, the torque signal indicating the torque indicated by the opening of the accelerator pedal. The dual-motor controller controls the torque output by the two drive motors to be less than or equal to the torque indicated by the opening of the accelerator pedal.

[0068] Other beneficial effects can be found in the description of the first aspect, and will not be repeated here. Attached Figure Description

[0069] Figure 1 is a schematic diagram of an electric vehicle entering a split road surface according to an embodiment of this application;

[0070] Figure 2 is a schematic diagram of torque control provided in an embodiment of this application;

[0071] Figure 3 is a schematic diagram of an electric vehicle provided in an embodiment of this application;

[0072] Figure 4 is a schematic diagram of the architecture of an electric vehicle provided in an embodiment of this application;

[0073] Figure 5 is a schematic diagram of dual-motor controller control provided in an embodiment of this application;

[0074] Figure 6 is a schematic diagram of a yaw suppression control provided in an embodiment of this application;

[0075] Figure 7 is a schematic diagram of a yaw control process provided in an embodiment of this application;

[0076] Figure 8 is a schematic diagram of distributed drive motor control provided in an embodiment of this application;

[0077] Figure 9 is a schematic flowchart of a yaw control provided in an embodiment of this application;

[0078] Figure 10 is a schematic diagram of the single-drive motor architecture control provided in an embodiment of this application;

[0079] Figure 11 is a schematic diagram of another yaw control process provided in an embodiment of this application;

[0080] Figure 12 is a schematic diagram of another yaw suppression control provided in an embodiment of this application. Detailed Implementation

[0081] The technical solutions in this application will now be described in conjunction with the accompanying drawings. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments.

[0082] When a vehicle suddenly enters a split-level road while traveling straight, or starts on a split-level road, the tire on the lower contact side may lose traction earlier than the tire on the higher contact side, causing the vehicle to yaw and affecting vehicle safety. As shown in Figure 1(a), when an electric vehicle enters a split-level road in a regenerative braking condition, if the torque on both sides cannot decrease rapidly and simultaneously, the regenerative braking force on the higher contact side will be greater than that on the lower contact side, causing the vehicle to yaw towards the higher contact side. As shown in Figure 1(b), when an electric vehicle enters a split-level road in a driving condition, or starts on a split-level road, if the torque on both sides cannot decrease rapidly and simultaneously, the traction force on the higher contact side will be greater than that on the lower contact side, causing the vehicle to yaw towards the lower contact side. Taking counterclockwise as the positive direction, the yaw moment of the vehicle can be expressed as:

[0083] In equation (1), F fl F fr F rl F rr These represent the traction forces applied to the four wheels from the ground, and W is the wheel track width.

[0084] The traction force can be expressed as: F i =μ i F zi(i=fl,fr,rl,rr) (2).

[0085] In equation (2), μ i F is the coefficient of adhesion between the four wheels and the ground. zi This represents the vertical load on the wheel.

[0086] When a vehicle suddenly enters a split-level road while traveling straight, or when starting on a split-level road system, if the torque of the front and rear wheels on the low-friction side has exceeded the road surface's adhesion limit, an F-type kink will occur. fl +F fr >F rl +F rr Or F fl +F fr <F rl +F rr In such a case, according to equation (1), the vehicle will experience significant yaw, which will affect driving safety.

[0087] In one possible implementation, as shown in Figure 2, traditional automotive chassis control is generally based on the ESP system. The ESP system determines whether the vehicle is slipping based on the relationship between wheel speed and vehicle speed. If the vehicle slips, the ESP system intervenes to implement torque intervention. The ESP system sends the adjusted torque to the vehicle controller, which then transmits it to the motor controller to ultimately achieve slip control, making the torque of the left and right wheels equal, thereby achieving yaw control.

[0088] It should be understood that traditional chassis control relies on wheel speed and vehicle speed. Due to the low accuracy of wheel speed sensors and the need for signal transmission from the ESP to the vehicle controller and then to the motor controller, the vehicle control loop frequency is low, approximately 100Hz, and the signal transmission time is prolonged, resulting in a delay of about 100ms for the entire control system. This can cause the wheels to fail to reduce torque in time when the car suddenly enters a split-level road or starts on a split-level road, causing the low-touch tires to exceed the road adhesion limit, resulting in significant yaw of the vehicle and affecting driving safety.

[0089] Based on the above problems, this application provides a dual-motor controller, control method and electric vehicle for suppressing yaw. When the electric vehicle enters or starts from a split road surface, if wheel slippage occurs, the drive system quickly adjusts the output torque to reduce the torque of both wheels simultaneously, thereby suppressing vehicle yaw and improving overall vehicle safety.

[0090] Figures 3 and 4 are schematic diagrams of the electric vehicle 10 provided in the embodiments of this application.

[0091] As shown in Figure 3, the electric vehicle 10 includes a vehicle controller 20, a drive motor 30, a motor controller 40, a power battery (not shown in the figure), and multiple wheels. The motor controller 40 is used to output current to the drive motor 30 to control the output torque of the drive motor 30 to drive or brake the electric vehicle 10. The electric vehicle 10 includes, but is not limited to, pure electric vehicles (pure EV / battery EV), hybrid electric vehicles (HEV), range-extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), and new energy vehicles (NEV).

[0092] Understandably, the power battery in the embodiments of this application can be a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-cadmium battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery, etc., and this application does not limit it. The power battery can also power other electrical devices in the vehicle, such as the in-vehicle air conditioner and in-vehicle media player.

[0093] The electric vehicle 10 can be a distributed four-motor drive architecture, with the drive motors positioned beside the driving wheels and controlled by individual motor controllers 40. Alternatively, the electric vehicle 10 can be a centralized drive motor architecture, with the drive motors for driving the two front wheels or two rear wheels grouped together and controlled by a dual-motor controller 60. There can be one or more motor controllers 40. A one-to-one correspondence can exist between the motor controller 40 and the drive motors, or one motor controller 40 can correspond to multiple drive motors. The motor controller 40 or the dual-motor controller 60 is used to control the output torque of one or more drive motors to drive the electric vehicle 10.

[0094] In one embodiment, as shown in FIG4(a), the electric vehicle 10 may be a distributed four-drive motor drive architecture, with drive motors located next to the driving wheels and controlled by separate motor controllers.

[0095] For example, the electric vehicle 10 includes four motor controllers: motor controller 41, motor controller 42, motor controller 43, and motor controller 44. The four motors include drive motor 31, drive motor 32, drive motor 33, and drive motor 34. Motor controller 41 controls drive motor 31 to drive wheel 51, motor controller 42 controls drive motor 32 to drive wheel 52, motor controller 43 controls drive motor 33 to drive wheel 53, and motor controller 44 controls drive motor 34 to drive wheel 54.

[0096] In one embodiment, as shown in FIG4(b), the electric vehicle 10 may also be a centralized four-drive motor drive architecture, in which two drive motors for driving the two front wheels or the two rear wheels are arranged together. A dual-motor controller 60 is used to control the two drive motors arranged together.

[0097] For example, the electric vehicle 10 includes two dual-motor controllers, namely dual-motor controller 61 and dual-motor controller 62. The four motors include drive motor 31, drive motor 32, drive motor 33, and drive motor 34. Dual-motor controller 61 controls drive motor 31 to drive wheel 51 and simultaneously controls drive motor 32 to drive wheel 52; dual-motor controller 62 controls drive motor 33 to drive wheel 53 and simultaneously controls drive motor 34 to drive wheel 54.

[0098] Based on wheel position, the four wheels can be divided into left front wheel, right front wheel, left rear wheel, and right rear wheel. According to axle arrangement, the left and right front wheels are coaxial and connected via the front axle, while the left and right rear wheels are coaxial and connected via the rear axle. Based on location, the left and left rear wheels are on the same side (left side), and the right front and right rear wheels are on the same side (right side). Of the four drive motors, the two motors driving the two front wheels are coaxial, and the two motors driving the two rear wheels are also coaxial.

[0099] In one embodiment, the electric vehicle 10 may also have the architecture shown in Figure 4(c), with one drive motor driving the two front wheels of the electric vehicle 10 and two drive motors driving the two rear wheels of the electric vehicle 10 respectively.

[0100] In one embodiment, the various architectures mentioned above can also be combined, for example, the front drive adopts a distributed drive motor architecture and the rear drive adopts a centralized drive motor architecture.

[0101] The electric vehicle 10 also includes an accelerator pedal and a steering wheel. The accelerator pedal is used to indicate the torque output to the wheels of the electric vehicle 10.

[0102] In one embodiment, the motor controller 40 or the dual-motor controller 60 includes a signal interface, which connects the vehicle controller 20 and other motor controllers 40. The vehicle controller 20 is signal-connected to the accelerator pedal. The vehicle controller 20 calculates the vehicle torque demand based on the accelerator pedal opening during the operation of the electric vehicle 10, and sends a torque signal to the motor controllers 40 according to the vehicle torque demand. Each motor controller 40 controls the corresponding drive motor to output torque to drive the corresponding wheel according to the torque signal indication.

[0103] In one embodiment, each motor controller 40 or the dual motor controller 60 can also be directly connected to the accelerator pedal and control the output torque of the corresponding drive motor according to the torque signal output by the accelerator pedal.

[0104] In one embodiment, each motor controller 40 or dual-motor controller 60 uses a resolver sensor via a signal interface. The resolver sensor detects the rotational speed of the drive motor 30 controlled by the motor controller 40 or dual-motor controller 60, and the motor controller 40 receives the signal from the resolver sensor. The motor controller 40 can also generate a rotational speed signal based on the signal from the resolver sensor and send the rotational speed signal to the other three motor controllers 40. Similarly, each motor controller 40 also receives rotational speed signals sent from the other three motor controllers 40.

[0105] The resolver sensor can accurately detect the position, direction and speed of the motor rotor, and is responsible for monitoring and extracting the rotational speed of the drive motor. It has a high sampling rate and is directly connected to the motor controller 40, resulting in short signal transmission time and higher stability.

[0106] In one embodiment, the motor controller 40 or the dual-motor controller 60 also acquires vehicle speed signals from the vehicle controller 20 or other sensors of the electric vehicle 10 via a signal interface. The vehicle speed signals are used to indicate the speed of the electric vehicle 10.

[0107] Figure 5 is a schematic diagram of a centralized four-drive motor architecture. For the centralized four-drive motor architecture, the working process of the dual-motor controller 60 for suppressing yaw of electric vehicles during driving on split-road surfaces provided in this application embodiment will be described below with reference to Figures 6 and 7.

[0108] Referring to Figures 6 and 7(a), from the first time t1 to the second time t2, the electric vehicle 10 travels normally on a uniform road surface. The road surface contacted by the two wheels at the first time t1 is a uniform road surface, and the difference in the adhesion coefficients of the two wheels on this uniform road surface is less than or equal to a preset difference. Specifically, the dual-motor controller 60 controls the torque indicated by the torque signals output by the two drive motors when the slip rates of both wheels are less than the preset slip rate at the first time t1. Since the slip rates of both wheels are less than the preset slip rate, the wheels do not slip.

[0109] Referring to Figures 6 and 7(b), at the second time t2, the electric vehicle 10 enters the split-path surface. The road surface in contact with the two wheels at the second time t2 is the split-path surface, and the difference in the coefficient of friction between the two wheels on the split-path surface is greater than a preset difference. Because the coefficient of friction of friction of the left and right wheels of the electric vehicle 10 is different, the coefficient of friction of one side is lower. When the wheel torque exceeds the maximum friction of the road surface, the wheel will slip. At this time, the dual-motor controller 60 controls the two drive motors to quickly reduce the torque so that the wheel recovers from the slipping state to the non-slipping state. Furthermore, the dual-motor controller 60 controls the two drive motors to simultaneously and quickly reduce the torque. If the torque reduction of the two motors is inconsistent, it will cause the traction force on the left and right wheels of the vehicle to be unequal, with the traction force on the high-friction side being greater than that on the low-friction side, causing the electric vehicle 10 to yaw towards the low-friction side. At the second time t2, the dual-motor controller 60 also actively controls the two drive motors 30 to simultaneously reduce the torque output so that the torque output by the two drive motors 30 is less than the torque indicated by the torque signal.

[0110] In one embodiment, at a second time t2, at least one of the two wheels has a slip ratio greater than a preset slip ratio and the accelerator pedal opening of the electric vehicle increases. The dual-motor controller 60 is also used to actively control the two drive motors 30 to reduce torque output.

[0111] The accelerator pedal in this application can also be called the power pedal or throttle pedal. The opening degree of the accelerator pedal indicates the amount of driving force required by the driver. The larger the opening degree of the accelerator pedal, the greater the driver's demand for driving force, and the greater the torque required from the drive motor. When the electric vehicle is not slipping, the dual-motor controller 60 can control the drive motor 30 to output the torque indicated by the accelerator pedal opening degree. The larger the accelerator pedal opening degree, the greater the torque output by the drive motor 30; the smaller the accelerator pedal opening degree, the smaller the torque output by the drive motor 30. The dual-motor controller controls the torque output by the drive motor to change with the change in the accelerator pedal opening degree.

[0112] Referring again to Figure 6, at the second time t2, the wheels slip. At this moment, the driver depresses the accelerator pedal. Although the torque value indicated by the torque signal increases, the torque output by the two drive motors 30 controlled by the dual-motor controller 60 does not increase accordingly. Instead, it actively controls the torque output of the two drive motors 30 to decrease to below the torque indicated by the torque signal, thereby reducing wheel slippage. When wheel slippage occurs, the dual-motor controller 60 operates in a closed-loop manner and no longer responds to changes in torque indicated by the torque signal. The dual-motor controller 60 rapidly adjusts the torque internally during wheel slippage, providing a quick response, reducing signal transmission time, and improving vehicle safety.

[0113] During normal operation of the electric vehicle, the dual-motor controller 60 responds to the torque signal sent by the vehicle controller to control the drive motors to output the torque indicated by the accelerator pedal. When the electric vehicle 10 suddenly enters a split-level road or starts on a split-level road, if the torque corresponding to the accelerator pedal opening indicated by the torque signal sent by the vehicle controller is greater than the maximum traction of the tires on the split-level road, the dual-motor controller can quickly adjust the torque. The dual-motor controller 60 controls the torque output of the two drive motors 30 to decrease and become less than the torque indicated by the torque signal. At this time, the torque output of the drive motors does not change with the torque command or the accelerator pedal opening. According to the solution of this application, when the wheels slip, the dual-motor controller quickly adjusts the torque internally, which does not change with the accelerator pedal opening, resulting in a rapid response, reduced signal transmission time, and improved vehicle safety.

[0114] When the electric vehicle 10 enters or starts on a split-path surface under feedback conditions, the dual-motor controller 60 controls the drive motor 30 to output reverse torque. When one wheel slips, the drive motor 30 driving that wheel needs to quickly reduce torque. Simultaneously, it also needs to control the other drive motor 30 to cooperate in quickly reducing torque. Otherwise, the traction force on the left and right wheels of the vehicle will be unequal, with the braking force on the high-traction side being greater than that on the low-traction side, causing the electric vehicle 10 to yaw towards the high-traction side. By simultaneously and quickly reducing the torque on both wheels, the yaw of the vehicle is suppressed.

[0115] The dual-motor controller 60 provided in this application embodiment can actively control the two drive motors 30 to simultaneously reduce torque output when two wheels on the same axle slip, thereby reducing slippage and improving vehicle driving safety.

[0116] Furthermore, the dual-motor controller 60 provided in this application embodiment can actively control the two drive motors 30 to reduce torque output simultaneously. That is, when at least one of the two wheels slips, the dual-motor controller 60 will actively adjust the two drive motors 30 to reduce torque output simultaneously, instead of controlling the two drive motors 30 to output torque according to the torque signal indicated by the torque signal output by the vehicle controller 20.

[0117] Referring specifically to Figure 6, between the first time t1 and the second time t2, the wheels do not slip, and the two drive motors 30 are controlled to output torque according to the torque signal indicated by the torque signal output by the vehicle controller. At the second time t2, the wheels slip. Between the second time t2 and the third time t3, the dual-motor controller 60 actively adjusts the two drive motors 30 to simultaneously reduce torque output, instead of controlling the two drive motors 30 to output torque according to the torque signal indicated by the vehicle controller. At the third time t3, when the slippage signal characteristic of the drive motor speed signal disappears, the drive motor torque recovers at a certain gradient, but will not exceed the torque indicated by the vehicle controller 20. In other words, the dual-motor controller 60 provided in this embodiment achieves internal closed-loop active torque control under wheel slippage conditions, instead of outputting torque according to the indication of the vehicle controller, thereby shortening the control link and improving control accuracy and control speed.

[0118] In one embodiment, at a second time t2, the change in rotational speed of at least one of the two drive motors 30 within a preset time period is greater than a preset value, and the dual-motor controller 60 is used to actively control the two drive motors 30 to reduce torque output simultaneously.

[0119] Referring to Figure 6, at the second time t2, when the electric vehicle 10 starts on the split road surface or passes through the split road surface during its operation, due to the different road surface adhesion coefficients of the left and right wheels of the electric vehicle 10, with one side having a lower road surface adhesion coefficient, the wheel torque will exceed the maximum road surface adhesion, causing the wheel to slip. The wheel speed will suddenly increase or decrease, and the wheel speed change will also be quickly reflected in the speed of the drive motor 30. The speed of the drive motor 30 can be detected by a resolver sensor. The resolver sensor can accurately detect the position, direction, and speed of the drive motor rotor, and is responsible for monitoring and extracting the rotational speed of the drive motor. It has a high sampling frequency and accuracy, and is directly connected to the dual-motor controller 60, resulting in short signal transmission time and higher stability. When the change value of the speed of one drive motor indicated by the resolver sensor of the electric vehicle 10 within a preset time period is greater than a preset value, the speed of one wheel driven by that drive motor changes abruptly. When the drive motor outputs positive torque, the change value within the preset time period increases; when the drive motor outputs reverse torque, the change value within the preset time period decreases.

[0120] The dual-motor controller 60 determines whether the wheel driven by the drive motor 30 is slipping based on the resolver signal from the drive motor 30. If the wheel slips, the controller needs to control the drive motor 30 to reduce its output torque. At the same time, the dual-motor controller 60 also needs to determine whether the wheel on the opposite side is slipping. If the wheel on the opposite side is slipping, the drive motor on the opposite side will also reduce its output torque.

[0121] When the electric vehicle 10 suddenly enters a split-path road or starts on a split-path road, the traditional chassis control system, due to its slow control, will cause the electric vehicle 10 to yaw significantly. However, the drive motor 30 is connected to the wheels via a half-shaft. Therefore, when the wheel torque exceeds the maximum road surface adhesion, the wheel speed will suddenly increase (driving) or decrease (feedback or braking). The change in wheel speed will be quickly reflected in the speed of the drive motor 30. The resolver sensor of the drive motor 30 has the characteristics of fast sensing, low latency, and high accuracy. Therefore, the dual-motor controller 60 can identify the speed characteristics of the drive motor 30 to determine whether the wheel torque exceeds the road surface limit. Then, based on the identified road surface adhesion, the torque can be quickly adjusted to ensure that the traction force on the left and right wheels of the vehicle is consistent, thereby achieving fast and high-precision control.

[0122] In one embodiment, between the second time t2 and the third time t3, the greater the change in the rotational speed of at least one drive motor within a preset time period, the greater the reduction in the output torque of the two drive motors 30 controlled by the dual motor controller 60.

[0123] In one embodiment, between the second time t2 and the third time t3, the smaller the driving torque of at least one wheel, the greater the reduction in the output torque of the two drive motors 30 controlled by the dual motor controller 60.

[0124] In one embodiment, between the second time t2 and the third time t3, the greater the difference between the slip ratio of at least one wheel and the preset slip ratio, the greater the reduction in the output torque of the two drive motors 30 controlled by the dual motor controller 60.

[0125] Referring to Figure 6, between the first time t1 and the second time t2, during the process of the dual-motor controller 60 controlling the two drive motors 30 to reduce torque output, the amount of reduction in torque output of the two drive motors 30 controlled by the dual-motor controller 60 can be determined based on the change in the rotational speed of the drive motors 30 within a preset time period, the drive torque of a wheel, or the difference between the slip ratio of a wheel and the preset slip ratio.

[0126] The dual-motor controller 60 can obtain the rotational speed of the drive motor 30 through the resolver signal of the resolver sensor. The rate of change of the drive motor 30's rotational speed or the change in rotational speed within a preset time period can reflect the change in adhesion between the wheel and the road surface to a certain extent. When the rate of change of the drive motor 30 or the change in rotational speed within the preset time period is greater, it indicates that the road surface adhesion has decreased significantly. In this case, in order to control the wheel from slipping, it is necessary to reduce the torque output of the drive motor more, so as to suppress the slippage of the electric vehicle 10 to the greatest extent.

[0127] The dual-motor controller 60 can calculate the actual output torque of the drive motor based on the actual output current. The actual output torque of the drive motor is directly proportional to the road surface adhesion. Therefore, the smaller the output torque of the drive motor, the smaller the maximum road surface adhesion, and in order to prevent wheel slippage, a greater reduction in the output torque of the drive motor is required.

[0128] The dual-motor controller 60 obtains the rotational speed of the drive motor 30 through the resolver signal from the resolver sensor. The angular velocity of the wheels can be calculated using the rotational speed of the drive motor 30 and the transmission ratio of the electric vehicle 10. Combining this with the wheel radius and the speed of the electric vehicle, the slip ratio of each wheel can be obtained. In this application, slip ratio can refer to slip displacement ratio. The wheels of the electric vehicle can achieve maximum adhesion at a preset slip ratio; therefore, by controlling the wheel slip ratio, the electric vehicle can fully utilize the road surface adhesion.

[0129] In one embodiment, between a second time t2 and a third time t3, the dual-motor controller 60 is specifically used to actively control the torque output of the two drive motors 30 to be equal.

[0130] Referring to Figure 6, between the second time t2 and the third time t3, during the process of the dual-motor controller 60 controlling the two drive motors 30 to reduce torque output, the reduction in torque output of the two drive motors 30 controlled by the dual-motor controller 60 is equal, thereby ensuring that the drive torque of the left and right wheels should remain equal. This can prevent the electric vehicle 10 from yawing due to the difference in drive torque between the left and right wheels, and improve the safety and reliability of the electric vehicle 10.

[0131] Meanwhile, to suppress wheel slippage, the reduction in output torque of the drive motor 30 should be selected based on the side with the greater reduction. The greater the wheel slip ratio, the greater the torque reduction required from the drive motor. The dual-motor controller 60 can determine which wheel has a greater slip ratio based on the change in rotational speed of the two drive motors within a preset time period.

[0132] The vehicle controller 20 sends a torque command to the dual motor controller 60 according to the driver's intention. The issued torque first passes through the road surface adhesion recognition and torque adjustment module. This module identifies the maximum road surface adhesion based on the resolver signals of drive motors 301 and 302. If the torque command is greater than the maximum road surface adhesion, the torque command of drive motors 301 and 302 is quickly adjusted and finally output to drive motors 301 and 302 so that the traction force on the left and right wheels of the vehicle is the same, thus achieving vehicle yaw suppression.

[0133] In one embodiment, between the second time t2 and the third time t3, the dual-motor controller 60 is specifically used to control the torque output by the two drive motors 30 to decrease at a preset rate of change or in a stepwise manner.

[0134] Referring to Figure 6, between the second time t2 and the third time t3, during the process of the dual-motor controller 60 controlling the two drive motors 30 to reduce torque output, the torque can be controlled to decrease in a certain gradient stepwise manner, or decrease according to a preset rate of change. This preset rate of change can be obtained through vehicle calibration, or it can be a preset value.

[0135] According to the solution of this application, when the wheel slips, the dual motor controller 60 controls the reduction of the drive motor torque output at a fixed rate of change or in a stepwise manner, so that the torque output of the drive motor 30 can be reduced slowly, which can effectively suppress slippage and reduce jerking, suppress vehicle yaw, and improve vehicle safety and comfort.

[0136] In one embodiment, between the second time t2 and the third time t3, the dual-motor controller 60 is used to actively control the absolute value of the torque output by the two drive motors 30 to be less than or equal to the absolute value of the torque indicated by the torque signal, and the direction of the torque output by the two drive motors 30 is the same as the direction of the torque indicated by the torque signal.

[0137] During the process of controlling the torque reduction of the drive motor 30, the dual motor controller 60 needs to limit the torque output of the drive motor 30. The absolute maximum value of the torque output of the drive motor 30 cannot exceed the torque indicated by the torque signal sent by the vehicle controller 20, and the final output torque is not allowed to reverse.

[0138] According to the solution in this application, in scenarios where an electric vehicle is driving straight onto a split road or starting on a split road, by rapidly sensing the road surface adhesion and rapidly adjusting the torque, the torque of the left and right wheels of the vehicle is kept equal, and the final torque is limited to not exceeding the torque given by the current vehicle controller, and torque reversal is not allowed, thereby suppressing vehicle yaw and improving driving safety.

[0139] Referring to Figures 6 and 7(c), at the third time t3, the electric vehicle 10 leaves the split road surface, and the road surface that the two wheels are in contact with at the third time t3 is a uniform road surface. The difference in the adhesion coefficients of the two wheels on the uniform road surface is less than or equal to a preset difference. In one embodiment, the dual-motor controller 60 is also used to control the torque output by the two drive motors 30 to stop decreasing at the third time t3 after the second time t2, when the slip rates of both wheels are less than or equal to the preset slip rate.

[0140] In one embodiment, after the third time t3, the dual motor controller 60 is also configured to control the torque output by the two drive motors 30 to increase to the torque indicated by the torque signal.

[0141] At the third time t3, when the slippage signal characteristic of the drive motor speed signal of electric vehicle 10 disappears (i.e., the slip ratio of the two wheels is less than the preset slip ratio), the dual-motor controller 60 re-controls the two drive motors 30 to output torque according to the torque signal indicated by the torque signal output by the vehicle controller. In other words, the dual-motor controller 60 will control the torque output value of the two drive motors 30 to increase to the torque value indicated by the torque signal. After the third time t3, when electric vehicle 10 is driving normally, the torque value indicated by the torque signal increases, and the dual-motor controller 60 will actively control the torque output of the two drive motors 30 to increase to the torque indicated by the torque signal. After the third time t3, as the torque value indicated by the torque signal increases, the torque output of the two drive motors 30 controlled by the dual-motor controller 60 will also increase accordingly.

[0142] In this embodiment, when the wheels are not slipping, the torque indicated by the torque signal output by the drive motor is controlled, without the need to reduce the torque to suppress the slip rate, thereby improving the driving performance and power of the vehicle.

[0143] Figure 8 is a schematic diagram of the distributed four-drive motor architecture. For the distributed four-drive motor architecture, the working process of the motor controller 40 to suppress the yaw of the electric vehicle during the driving process on the split road is similar to the working process of the aforementioned dual motor controller 60. Some differences are briefly explained below. For the specific process, please refer to Figures 6 and 7.

[0144] The motor controller 40 provided in this application can be any one of multiple motor controllers. The following embodiments only use any one motor controller 40 as an example. The operation of other motor controllers can be understood similarly by referring to the description.

[0145] As shown in Figure 8, the electric vehicle 10 includes multiple motor controllers 40 and multiple drive motors 30. One motor controller 401 controls the output torque of one drive motor 301 to drive or brake the electric vehicle, and another motor controller controls the output torque of another drive motor 302 to drive or brake the electric vehicle. One drive motor 301 and the other drive motor 302 drive either the two front wheels or the two rear wheels of the electric vehicle 10, respectively. The drive motors 30 at both ends of a single axle are controlled separately, and the torque of the left and right drive motors 30 can be controlled independently. The left and right wheel electric drive systems communicate in real time via a controller area network (CAN) bus or other means.

[0146] At the second moment t2, the change in rotational speed of one drive motor 301 of the electric vehicle 10 within a preset time period is greater than a preset value, and a motor controller 401 is used to control one drive motor 301 to reduce the output torque.

[0147] In one embodiment, at a second time t2, when the change in rotational speed of one drive motor 301 of the electric vehicle 10 within a preset time period is less than or equal to a preset value, and the change in rotational speed of the other drive motor 302 within a preset time period is greater than a preset value, the torque output by one drive motor 301 is controlled to be reduced to be equal to the torque output by the other drive motor 302.

[0148] The left and right motor controllers can communicate with each other using CAN or a universal asynchronous receiver / transmitter (UART). The left and right motor controllers communicate in real time, transmitting the current torque adjustment of the driven motor to the other motor controller via CAN or other communication methods.

[0149] When the electric vehicle 10 starts or travels on a split-level road, due to the different coefficients of friction of the left and right wheels, with one side having a lower coefficient of friction, the wheel torque may exceed the maximum friction, causing wheel slippage. This results in a sudden increase or decrease in wheel speed, which is quickly reflected in the speed of the drive motor. The speed of the drive motor 30 can be detected by a resolver sensor. The resolver sensor accurately detects the position, direction, and speed of the drive motor rotor, monitoring and extracting the rotational speed of the drive motor. It has a high sampling rate, is directly connected to the motor controller, has a short signal transmission time, and higher stability. When the change in the speed of one drive motor 301 indicated by the resolver sensor of the electric vehicle 10 within a preset time period exceeds a preset value, the speed of the wheel driven by that drive motor 301 changes abruptly. When the drive motor outputs positive torque, the change within the preset time period increases; when the drive motor outputs reverse torque, the change within the preset time period decreases.

[0150] For the electric vehicle 10 with distributed drive motors, when the electric vehicle 10 enters or starts on a split road surface in driving mode, the motor controller 40 controls the drive motor 30 to output positive torque. The speed of the drive motor 30 used to drive the wheels on the low-traction side of the road surface suddenly increases. At this time, the drive motor 30 needs to quickly reduce torque; otherwise, the wheels on the low-traction side will slip, causing the electric vehicle 10 to lose control. At the same time, it is also necessary to control the drive motor 30 on the other side to quickly reduce torque in coordination; otherwise, the traction force on the left and right wheels of the vehicle will be unequal, with the traction force on the high-traction side of the road surface being greater than that on the low-traction side of the road surface, causing the electric vehicle 10 to yaw towards the low-traction side. When the electric vehicle 10 enters or starts on a split-path surface under feedback conditions, the motor controller 40 controls the drive motor 30 to output reverse torque. The speed of the drive motor 30, which drives the wheel on the low-traction side of the surface, suddenly decreases. At this time, the drive motor 30 needs to quickly reduce its torque. Simultaneously, it also needs to control the other drive motor 30 to coordinate a rapid reduction in torque; otherwise, the traction force on the left and right wheels will be unequal, with the braking force on the high-traction side being greater than that on the low-traction side, causing the electric vehicle 10 to yaw towards the high-traction side. By simultaneously and rapidly reducing the torque on both wheels, the yaw is suppressed.

[0151] In one embodiment, at a second time t2, when the change in rotational speed of one drive motor 301 within a preset time period is greater than a preset value, and the change in rotational speed of another drive motor 302 within a preset time period is greater than a preset value but less than or equal to the change in rotational speed of one drive motor 301 within a preset time period, a motor controller 401 controls one drive motor 301 to reduce its output torque. When the change in rotational speed of one drive motor 301 within a preset time period is greater than a preset value, and the change in rotational speed of another drive motor 302 within a preset time period is greater than a preset value and greater than the change in rotational speed of one drive motor 301 within a preset time period, one drive motor 301 is controlled to reduce its output torque to be equal to that of the other drive motor 302.

[0152] The motor controller 40 determines whether the wheel driven by the drive motor 30 is slipping based on the resolver signal from the drive motor 30. If the wheel slips, the drive motor needs to reduce its output torque. Simultaneously, the motor controller 40 also needs to determine whether the wheel on the opposite side is slipping. If the wheel on the opposite side is slipping, the drive motor 30 on that side will also reduce its output torque. To suppress vehicle yaw, the reduced output torque of the drive motors 30 on both sides should be consistent.

[0153] In one embodiment, at a third time t3, the change in rotational speed of a drive motor 301 of the electric vehicle 10 within a preset time period is reduced to less than or equal to a preset value, and a motor controller 401 is further used to control a drive motor 301 to stop reducing output torque and increase output torque.

[0154] In one embodiment, at a third time t3, a motor controller 401 controls a drive motor 301 to stop reducing the output torque and gradually increase the output torque in a stepwise manner or at a preset rate of change to the torque indicated by the opening of the accelerator pedal of the electric vehicle.

[0155] During the torque reduction process, when the change in the rotational speed of the drive motor 30 within a preset time period decreases to less than or equal to a preset value, the wheel slippage characteristic disappears, the electric vehicle 10 no longer slips, and the torque output by the drive motor 30 can be gradually increased in a stepped manner or at a preset rate of change, gradually returning to the torque indicated by the accelerator pedal opening. Increasing the torque in a stepped manner or at a preset rate of change can maintain the stability of the electric vehicle 10.

[0156] In one embodiment, at a third time t3, when the change in the rotational speed of another drive motor 302 within a preset time period decreases to less than or equal to a preset value, a motor controller 401 is further configured to control one drive motor 301 to stop reducing the output torque and increase the output torque.

[0157] When the slippage characteristics of the opposite wheel disappear, the electric vehicle 10 no longer slips, and the motor controller 40 can control the torque output of the drive motor 30 to increase again.

[0158] This application provides a control method for an electric vehicle. The control method provided in this application will be further described below with reference to Figures 6 and 7.

[0159] In one embodiment, the control method includes: at a first time t1, when the slip ratios of both coaxial wheels of the electric vehicle 10 are less than a preset slip ratio, controlling the driving torque of the two wheels to the torque indicated by the accelerator pedal opening of the electric vehicle. At a second time t2 after the first time t1, when the slip ratio of at least one of the two wheels is greater than the preset slip ratio, actively controlling the driving torque of the two wheels to decrease.

[0160] Referring to Figures 6 and 7, from the first time t1 to the second time t2, the electric vehicle 10 is driving normally on a uniform road surface. The slip ratios of both wheels are less than the preset slip ratios, and the wheels do not slip. The driving torque of the two coaxial wheels of the electric vehicle is controlled to be the torque indicated by the accelerator pedal opening. At the second time t2, after the first time t1, the electric vehicle 10 enters a split road surface. Due to the different road surface adhesion coefficients of the left and right wheels of the electric vehicle 10, the road surface adhesion coefficient on one side is lower. When the wheel torque exceeds the maximum road surface adhesion, the wheel will slip. At this time, the two drive motors are controlled to quickly reduce the torque so that the wheel recovers from the slipping state to the non-slipping state, thereby allowing the electric vehicle to continue driving safely. The control method provided in this embodiment can quickly reduce the driving torque when the wheels of the electric vehicle 10 slip, thereby quickly recovering the wheels of the electric vehicle 10 from the slipping state to the non-slipping state, improving the driving safety of the electric vehicle.

[0161] In one embodiment, the control method further includes: at a third time t3 after the second time t2, when the slip ratios of both wheels are less than or equal to a preset slip ratio, controlling the driving torque of the two wheels to stop decreasing. After the third time t3, controlling the driving torque of the two wheels to increase to the torque indicated by the accelerator pedal opening.

[0162] Referring back to Figure 6, between the second time t2 and the third time t3, the two drive motors 30 are actively controlled to simultaneously reduce their torque output, instead of controlling the torque output of the two drive motors 30 based on the torque signal indicated by the vehicle controller. At the third time t3, after the slip ratio of the two wheels is less than the preset slip ratio, the wheel slippage disappears. Therefore, it is necessary to control the two drive motors to stop reducing torque output and control the torque output of the two drive motors to increase, so that the electric vehicle 10 returns to normal driving status. However, during the process of controlling the increase of the torque output of the two drive motors, the torque output of the two drive motors is controlled not to exceed the torque indicated by the accelerator pedal opening. Preferably, the torque output of the two drive motors is controlled to be equal to the torque indicated by the accelerator pedal opening, thereby controlling the electric vehicle 10 to respond to the driver's operation of the accelerator pedal, improving the driving performance and power of the vehicle.

[0163] In one embodiment, the control method specifically includes controlling the driving torque of the two wheels to be equal between the second time t2 and the third time t3.

[0164] Referring to Figure 6, between the second time t2 and the third time t3, during the process of controlling the two drive motors 30 to reduce torque output, the reduction in torque output of the two drive motors 30 is equal, thereby ensuring that the drive torque of the left and right wheels should remain equal. This can prevent the electric vehicle 10 from yawing due to the difference in drive torque between the left and right wheels, and improve the safety and reliability of the electric vehicle 10.

[0165] As shown in Figure 9, the overall control flow for electric vehicles with distributed drive motors or centralized drive motor architectures is as follows:

[0166] The vehicle controller 20 sends torque commands to the left and right drive motors 30 to the motor controller 40 or the dual motor controller 60.

[0167] The motor controller 40 or the dual-motor controller 60 determines whether the wheel is slipping based on the resolver signal from the drive motor 30. If the wheel is slipping, the torque of the drive motor 30 on that side is reduced at a fixed gradient, while the torque adjustment amount ΔT1 is sent to the drive motor 30 on the opposite side. If the wheel is not slipping, the torque of the drive motor is increased at a certain gradient to the torque given by the vehicle controller 20, that is, the torque adjustment amount ΔT1 is reduced to 0.

[0168] The motor controller 40 or the dual-motor controller 60 determines whether the opposite drive motor 30 is slipping. If the opposite drive motor 30 is slipping, the final drive motor torque adjustment is the larger of the absolute values ​​of the current drive motor torque adjustment and the opposite drive motor torque adjustment. If the opposite drive motor 30 is not slipping, the final drive motor torque adjustment is the current drive motor torque adjustment ΔT1.

[0169] The final torque of the drive motor 30 is limited, and the absolute maximum value cannot exceed the torque indicated by the torque signal of the current vehicle controller 20, and the torque is not allowed to reverse. The torque adjustment of the two drive motors is taken as the larger absolute value, so that the torque of the two drive motors is reduced at the same time, and the left and right wheels are driven with low road surface adhesion, eliminating yaw moment and suppressing vehicle yaw.

[0170] Figure 6 shows the control results of yaw suppression on the split road surface of electric vehicle 10, with the left side of the vehicle being a low-friction road surface and the right side being a high-friction road surface.

[0171] Figure 10 is a schematic diagram of an electric vehicle with a single-motor drive architecture. In this architecture, a single drive motor drives two wheels on the same axle. The electric vehicle 10 drives both front wheels or both rear wheels simultaneously via drive motor 30. Drive motor 30 connects the left and right wheels through a mechanical differential. The torque transmitted by the drive motor to both wheels is the same. Therefore, reducing the torque output by drive motor 30 can simultaneously reduce the torque on both wheels.

[0172] The electric vehicle 10 drives both front wheels or both rear wheels simultaneously via a drive motor 30. The drive motor 30 connects the left and right wheels via a mechanical differential. The torque transmitted by the drive motor to both left and right wheels is the same. Therefore, reducing the torque output by the drive motor 30 can simultaneously reduce the torque on both left and right wheels.

[0173] When the vehicle suddenly enters a split road or starts on a split road, the motor controller 40 detects a tendency for the wheels to slip at a frequency of 1000Hz. Based on the torque command of the vehicle controller 20, the drive motor simultaneously and rapidly reduces the torque of the left and right wheels to suppress wheel slippage. When road surface adhesion is restored, the torque of the left and right wheels is restored to the torque command of the vehicle controller 20 at a certain gradient. Throughout the process, the absolute value of the torque of the drive motor 30 does not exceed the torque command of the vehicle controller 20.

[0174] As shown in Figure 11, the overall control flow for the electric vehicle 10 with a single drive motor is as follows:

[0175] The vehicle controller 20 sends torque commands to the motor controller 40.

[0176] The motor controller 40 determines whether the wheel is slipping based on the resolver signal from the drive motor 30. If the wheel is slipping, the torque of the drive motor 30 is reduced at a fixed gradient. If the wheel is not slipping, the torque of the drive motor is increased at a certain gradient until it reaches the torque given by the vehicle controller 20, i.e., the torque adjustment amount is reduced to 0. The final torque of the drive motor 30 is limited, and the absolute maximum value cannot exceed the torque indicated by the torque signal of the current vehicle controller 20, and the torque is not allowed to reverse.

[0177] Figure 12 shows the control results of the single-drive motor architecture electric vehicle 10 in suppressing yaw when starting at full throttle on a split road surface with the left side of the vehicle being a low-friction surface and the right side being a high-friction surface.

[0178] Electric vehicle 10 operates normally from the first to the second moment without wheel slippage. When electric vehicle 10 enters or starts on a split-path surface at the second moment, if the torque signal indicated by the vehicle controller 20 is greater than the low-adhesion side of the road surface, the motor controller 40 identifies the low-adhesion side of the road surface based on the resolver signal and outputs compensating torque to ensure that the drive motor torque is at the maximum road surface adhesion, preventing the vehicle from yawing. At the third moment, after the slippage signal characteristic of the drive motor speed signal disappears, the drive motor torque recovers at a certain gradient, but will not exceed the torque indicated by the vehicle controller 20. As can be seen from Figure 12, the front and rear drive motors are independently adjusted, and both can output motor torque at the maximum road surface adhesion, preventing the vehicle from yawing.

[0179] According to the solution in this application, in scenarios where an electric vehicle is driving straight onto a split road or starting on a split road, by rapidly sensing the road surface adhesion and rapidly adjusting the torque, the torque of the left and right wheels of the vehicle is kept equal, thereby suppressing vehicle yaw and improving driving safety.

[0180] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dual motor controller, characterized by, The dual-motor controller is used to suppress the yaw of the electric vehicle during its travel on a split road surface. The dual-motor controller is used to control the output torque of the two drive motors to drive the two coaxial wheels of the electric vehicle respectively. The dual-motor controller is specifically used for: At the first moment, the slip ratio of both wheels is less than the preset slip ratio, and the torque indicated by the torque signal output by the two drive motors is controlled. At a second moment after the first moment, if the slip ratio of at least one of the two wheels is greater than a preset slip ratio, the two drive motors are actively controlled to reduce torque output simultaneously.

2. The dual motor controller of claim 1, wherein, The road surface that the two wheels are in contact with at the first moment is a uniform road surface, and the road surface that the two wheels are in contact with at the second moment is a split road surface. The difference in the coefficient of adhesion of the two wheels on the uniform road surface is less than or equal to a preset difference, while the difference in the coefficient of adhesion of the two wheels on the split road surface is greater than a preset difference.

3. The dual motor controller of claim 1 or 2, wherein, The dual-motor controller is also used for: At the second moment, the two drive motors are actively controlled to simultaneously reduce their torque output so that the torque output by the two drive motors is less than the torque indicated by the torque signal.

4. The dual motor controller of any one of claims 1-3, wherein, The dual-motor controller is also used for: At the third moment following the second moment, the slip ratios of both wheels are less than or equal to the preset slip ratio, and the torque output by the two drive motors is controlled to stop decreasing.

5. The dual motor controller of claim 4, wherein, The dual-motor controller is also used for: After the third moment, the torque output of the two drive motors is increased to the torque indicated by the torque signal.

6. The dual motor controller of any one of claims 1-3, wherein, The dual-motor controller is also used for: At the second moment, if the slip ratio of at least one of the two wheels is greater than the preset slip ratio and the opening of the accelerator pedal of the electric vehicle increases, the two drive motors are actively controlled to reduce torque output.

7. The dual motor controller of any one of claims 1-6, wherein, The dual-motor controller is specifically used for: At the second moment, if the change in rotational speed of at least one of the two drive motors within a preset time period is greater than a preset value, the two drive motors are actively controlled to simultaneously reduce torque output.

8. The dual motor controller of claim 4, wherein, The dual-motor controller is also used for: Between the second and third time points, the torque output of the two drive motors is controlled to be equal.

9. The dual motor controller of claim 4, wherein, The dual-motor controller is specifically used for: Between the second and third time points, the torque output by the two drive motors is controlled to decrease at a preset rate of change or in a stepwise manner.

10. The dual motor controller of claim 4, wherein, The dual-motor controller is specifically used for: Between the second and third time points, the greater the change in the rotational speed of the at least one drive motor within a preset time period, the greater the reduction in the output torque of the two drive motors.

11. The dual motor controller of claim 4, wherein, The dual-motor controller is specifically used for: Between the second and third time points, the greater the difference between the slip ratio of the at least one wheel and the preset slip ratio, the greater the reduction in the output torque of the two drive motors.

12. A control method of an electric vehicle, characterized by, The control method is used to suppress the yaw of the electric vehicle while it is traveling on a split road surface, and the control method includes: At the first moment, the slip ratios of the two coaxial wheels of the electric vehicle are both less than the preset slip ratio, and the driving torque of the two wheels is controlled to be the torque indicated by the accelerator pedal opening of the electric vehicle. At a second moment after the first moment, if the slip ratio of at least one of the two wheels is greater than a preset slip ratio, the driving torque of the two wheels is actively reduced.

13. The control method according to claim 12, characterized by, The control method further includes: At the third moment after the second moment, the slip ratio of both wheels is less than or equal to the preset slip ratio, and the driving torque of the two wheels is controlled to stop decreasing; After the third moment, the driving torque of the two wheels is increased to the torque indicated by the accelerator pedal opening.

14. The control method according to claim 13, characterized by, The control method specifically includes: Between the second and third time points, the driving torque of the two wheels is controlled to be equal.

15. An electric vehicle characterized by comprising: The electric vehicle includes a dual-motor controller, a vehicle controller, and an accelerator pedal as described in any one of claims 1-11. The vehicle controller is used to send a torque signal to the dual-motor controller, the torque signal being used to indicate the torque indicated by the opening of the accelerator pedal of the electric vehicle. The dual-motor controller is used to control the torque output by the two drive motors to be less than or equal to the torque indicated by the opening of the accelerator pedal.

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