Dual-motor controller, control method and electric vehicle

Abstract

The invention discloses a dual-motor controller, a control method and an electric vehicle, relates to the field of new energy automobiles, and can be applied to pure electric vehicles and hybrid vehicles. The dual-motor controller is used for restraining yawing of the electric vehicle in the running process on the split road surface, and the dual-motor controller is used for controlling the two driving motors to output torque so as to respectively drive two coaxial wheels of the electric vehicle. The dual-motor controller is specifically used for controlling the two driving motors to output torque indicated by torque signals at the first moment when the slip rates of the two wheels are both smaller than the preset slip rate. And at the second moment after the first moment, the slip rate of at least one of the two wheels is larger than the preset slip rate, and the two driving motors are actively controlled to reduce torque output at the same time. According to the scheme, the motor torque can be rapidly adjusted, the torques of the left wheel and the right wheel are equal, vehicle yawing is restrained, and the safety of the whole vehicle is improved.

Description

Technical Field

[0001] The present 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 Art

[0002] A split road refers to a road with different adhesion coefficients on the left and right sides of the vehicle. When a vehicle is driving straight and suddenly enters a split road or starts on a split road, the tire with low adhesion may lose grip earlier than the tire with high adhesion, causing the vehicle to sway sideways and affecting vehicle safety.

[0003] Traditional chassis control is generally based on the electronic stability program (ESP) of the vehicle body, which uses wheel speed sensors to determine whether the vehicle is slipping, and then performs torque control. However, due to the low accuracy of the wheel speed sensor, the vehicle control loop frequency is low, the transmission time is extended, and the entire control system has a long delay. This will cause the wheels to fail to reduce torque in time when the vehicle suddenly enters or starts on an open road, and the driving force of the low-end tire exceeds the road adhesion limit, causing the vehicle to sway significantly, affecting driving safety.

[0004] Therefore, how to suppress the lateral movement of the vehicle on the oncoming road is a problem that needs to be solved. Summary of the invention

[0005] The present application provides a dual-motor controller, a control method and an electric vehicle. When the electric vehicle enters or starts from an open road, if wheel slip occurs, the drive system quickly adjusts the output torque to reduce the torque of the wheels on both sides, thereby suppressing the vehicle's sway and improving the safety of the entire vehicle.

[0006] In a first aspect, the present application provides a dual-motor controller, which is used to suppress the yaw of an electric vehicle during driving on an open road, and the dual-motor controller is used to control the output torque of two drive motors to drive two coaxial wheels of the electric vehicle respectively. The dual-motor controller is specifically used to control the torque indicated by the output torque signal of the two drive motors when the slip rate of the two wheels is less than a preset slip rate at a first moment. At a second moment after the first moment, the slip rate of at least one of the two wheels is greater than the preset slip rate, and the two drive motors are actively controlled to reduce the torque output at the same time.

[0007] The dual-motor controller is suitable for electric vehicles or hybrid vehicles. The electric vehicle can be a distributed motor or a centralized motor architecture with multiple drive motors. The drive motor can be a wheel-side motor or a hub motor, and the drive motor can independently drive one wheel of the vehicle. The dual-motor controller can output three-phase AC power to the two drive motors respectively, thereby controlling the output torque of the two drive motors respectively, and the wheels driven by the two drive motors are two coaxial wheels. The two coaxial wheels can be the two front wheels of the electric vehicle or the two rear wheels of the electric vehicle.

[0008] The drive motor includes a stator winding and a rotor. The dual motor controller can control the output torque of the drive motor by outputting alternating current to the three-phase stator winding. The dual motor controller can change the strength and direction of the stator magnetic field by adjusting the magnitude of the input stator winding current and the phase of the three-phase current, thereby changing the interaction force between the stator and the rotor, that is, controlling the drive motor to output positive torque or reverse torque. Reverse torque can also be called negative torque. During the forward driving of an electric vehicle, positive torque is used to drive the vehicle, and reverse torque is used to brake the vehicle. During the reversing of an electric vehicle, positive torque is used to brake the vehicle, and reverse torque is used to drive the vehicle. The dual motor controller can change the phase of the three-phase current output to the drive motor so that the rotor cuts the magnetic field generated by the stator winding, and the kinetic energy of the rotor is converted into electrical energy and input into the power battery. At this time, 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 positive torque or reverse torque output by the motor. It should be understood that the present application uses the forward driving of an electric vehicle as an example for explanation, and similar descriptions can be referred to in the scenario of the electric vehicle reversing. The direction of the torque output by the drive motor can be modified accordingly, and the function of the torque should remain consistent.

[0009] It should be understood that reducing the torque output in the present 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 the torque at this time 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 the torque at this time means increasing the torque value and reducing the absolute value of the torque value of the reverse torque.

[0010] At the first moment, the slip rates of both wheels are less than the preset slip rates, and both wheels are not slipping. During the driving process of the electric vehicle, the dual motor controller can receive a torque signal from the vehicle controller, and the torque signal is used to indicate the torque output by the two drive motors. When both wheels are not slipping, the dual motor controller controls the two drive motors to output the torque indicated by the torque signal. When the wheels are not slipping, the drive motors are controlled to output the torque indicated by the torque signal, without reducing the torque to suppress the slip rate, thereby improving the driving performance and power of the vehicle.

[0011] 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, at least one wheel slips, and the torque output needs to be reduced. When the electric vehicle starts on a split road or passes through a split road during driving, the road adhesion coefficients of the left and right wheels of the electric vehicle are different, and the road adhesion coefficient on one side is lower, the wheel torque will exceed the maximum adhesion of the road, and the wheel will slip.

[0012] The slip rate of at least one of the two wheels is greater than the preset slip rate, which includes that the slip rate of one of the two wheels is greater than the preset slip rate, and the slip rate of the other wheel is less than or equal to the preset slip rate, at which time one wheel slips and the other wheel does not slip. The slip rate of at least one of the two wheels is greater than the preset slip rate, which also includes that the slip rates of both wheels are greater than the preset slip rate, at which time both wheels slip.

[0013] For electric vehicles with distributed drive motors, when the electric vehicle enters the split road or starts on the split road in a driving condition, the dual motor controller controls the two drive motors to output positive torque. When one wheel slips, the drive motor used to drive the wheel needs to reduce the torque quickly, otherwise the wheel on the low adhesion side will slip, causing the electric vehicle to lose control. At the same time, it is also necessary to control the drive motor on the other side to quickly reduce the torque in coordination, otherwise the traction force on the left and right wheels of the vehicle will be unequal, the traction force on the high adhesion side road surface will be greater than the traction force on the low adhesion side road surface, and the electric vehicle will yaw to the low adhesion side. When the electric vehicle enters the split road or starts on the split road in a feedback condition, the dual motor controller controls the drive motor to output reverse torque. When one wheel slips, the drive motor used to drive the wheel needs to reduce the torque quickly. At the same time, it is also necessary to control the drive motor on the other side to quickly reduce the torque in coordination, otherwise the traction force on the left and right wheels of the vehicle will be unequal, the braking force on the high adhesion side road surface will be greater than the braking force on the low adhesion side road surface, and the electric vehicle will yaw to the high adhesion side. By quickly reducing the torque on the left and right wheels at the same time, the vehicle yaw is suppressed.

[0014] According to the solution of the present application, in a scenario where an electric vehicle is driving straight into an open road or starting on an open road, the torque of the left and right wheels of the vehicle can be kept reduced at the same time through rapid perception of road adhesion and rapid adjustment of torque, thereby preventing slipping, suppressing vehicle sway and improving driving safety.

[0015] In combination with the first aspect, in certain implementations of the first aspect, the road surface contacted by the two wheels at the first moment is a uniform road surface, and the road surface contacted by the two wheels at the second moment is an open road surface. The difference in adhesion coefficients of the two wheels on the uniform road surface is less than or equal to a preset difference, and the difference in adhesion coefficients of the two wheels on the open road surface is greater than the preset difference.

[0016] At the first moment, the ground contacted by the wheels of the electric vehicle is a uniform road surface, the road adhesion coefficients on the left and right sides of the electric vehicle are uniform, the difference in adhesion coefficients of the left and right wheels on the road surface is less than or equal to the preset difference, and the slip rates of the left and right wheels are similar.

[0017] At the second moment, the ground contacted by the wheels of the electric vehicle is an open road, the road adhesion coefficients on the left and right sides of the electric vehicle are different, the difference in adhesion coefficients of the left and right wheels on the road is greater than a preset difference, and the slip rates of the left and right wheels may be quite different. The dual-motor controller is specifically used to actively control the two drive motors to reduce the torque output simultaneously when the slip rate of one of the two wheels is greater than a preset slip rate and the slip rate of one wheel is greater than the slip rate of the other wheel of the two wheels during the driving or starting process of the electric vehicle.

[0018] When an electric vehicle enters a split road or starts on a split road, the adhesion coefficients of the roads on both sides are not equal, so the slip rates of the wheels on both sides may be different. The slip rate of the wheel on one side is greater than the preset slip rate, and skidding occurs. The slip rate of the wheel on the other side is less than the slip rate of the wheel on one side, and there may be no skidding. At this time, for the slipping wheel, it is necessary to control the drive motor used to drive the slipping wheel to reduce the torque, so as to suppress the wheel slip. For the non-slipping wheel, it is not necessary to suppress the wheel slip, but in order to suppress the yaw of the electric vehicle, it is necessary to reduce the drive torque synchronously.

[0019] According to the solution of the present application, in a scenario where an electric vehicle is driving straight into an open road or starting on an open road, when one side of the wheel slips, the torque of the left and right wheels of the electric vehicle is reduced simultaneously, thereby preventing the wheels from slipping and suppressing the vehicle's swaying, thereby improving driving safety.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is also used to actively control the two drive motors to simultaneously reduce the torque output at the second moment so that the torque output by the two drive motors is less than the torque indicated by the torque signal.

[0021] At the second moment, when the slip rate of at least one of the two wheels is greater than the preset slip rate, at least one wheel slips, and the torque output needs to be reduced at this time, 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 inside the dual-motor controller.

[0022] According to the solution of the present application, when the wheel slips, the dual-motor controller quickly adjusts the torque internally, responds quickly, reduces signal transmission time, and improves vehicle safety.

[0023] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is also used to: at a third moment after the second moment, the slip rates of the two wheels are less than or equal to a preset slip rate, and the torque output by the two drive motors is controlled to stop decreasing.

[0024] At the third moment, in the process of reducing torque, the slip rates of both wheels are less than or equal to the preset slip rates, the slip characteristics disappear, and the wheels on both sides no longer slip. At this time, the dual-motor controller controls the torque output by the two drive motors to stop reducing.

[0025] According to the solution of the present application, when the slipping characteristics of the electric vehicle disappear, the drive motor is controlled to stop reducing the torque output, thereby preventing the electric vehicle from losing power and improving the vehicle's controllability and safety.

[0026] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is further 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.

[0027] At the third moment, in the process of reducing the torque, the slip rates of both wheels are less than or equal to the preset slip rate, the slip feature disappears, and the wheels on both sides no longer slip. At this time, the dual-motor controller controls the torque output by the two drive motors to stop reducing, and controls the torque output by the two drive motors to increase again. The dual-motor controller can change in response to the torque change indicated by the torque signal.

[0028] According to the solution of the present application, when the slipping characteristics of the electric vehicle disappear, the drive motor is re-controlled to increase the output torque, restore the traction of the electric vehicle, and improve the vehicle's controllability and safety.

[0029] In combination with the first aspect, in certain 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.

[0030] The accelerator pedal in this application may also be referred to as an accelerator pedal or an acceleration pedal. The opening of the accelerator pedal can indicate the driving force required by the driver. The larger the opening of the accelerator pedal, the greater the driver's demand for driving, and the corresponding torque required to be output by the drive motor is also greater. 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 according to the accelerator pedal opening. The larger the accelerator pedal opening, the greater the torque output by the drive motor, and the smaller the accelerator pedal opening, 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 of the accelerator pedal opening.

[0031] When the electric vehicle is driving normally, the dual motor controller controls the drive motor to output the torque indicated by the accelerator pedal in response to the torque signal sent by the vehicle controller. When the electric vehicle suddenly enters a split road or starts on a split road, and the torque corresponding to the accelerator pedal opening indicated by the torque signal sent by the vehicle controller is greater than the maximum adhesion of the tire on the split road, the dual motor controller can quickly adjust the torque, and the torque output by the drive motor does not change with the torque command or the accelerator pedal opening.

[0032] At the second moment, even if the driver presses the accelerator pedal and the opening of the accelerator pedal increases, since the slip rate of at least one of the two wheels is greater than the preset slip rate, there is a slipping phenomenon, so it is unable to respond to the change 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.

[0033] According to the solution of the present application, when the wheel slips, the torque is quickly adjusted internally by the dual-motor controller, which does not change with the opening of the accelerator pedal, and responds quickly, reducing the signal transmission time and improving vehicle safety.

[0034] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is specifically used to actively control the two drive motors to simultaneously reduce the torque output when, at the second moment, a 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.

[0035] When an electric vehicle starts on a split road or passes through a split road during driving, due to the different adhesion coefficients of the road surface contacted by the left and right wheels of the electric vehicle, the adhesion coefficient of the road surface on one side is lower, and the wheel torque will break through the maximum adhesion of the road surface, the wheel will slip, the wheel speed will suddenly rise or fall, and the speed change of the wheel will also quickly react to the speed of the drive motor. The speed of the drive motor can be detected by a resolver sensor. The resolver sensor can accurately detect the position, direction and speed of the drive motor rotor, is responsible for monitoring and extracting the rotation speed of the drive motor, has a high sampling rate, and is directly connected to the dual motor controller, with a short signal transmission time and higher stability. When the speed of a drive motor indicated by the resolver sensor of the electric vehicle changes by more than a preset value within a preset time length, the speed of a wheel driven by the drive motor changes suddenly. When the drive motor outputs positive torque, the change value within the preset time length is an increase value, and when the drive motor outputs reverse torque, the change value within the preset time length is a decrease value.

[0036] The dual-motor controller determines whether the wheel driven by the drive motor is slipping based on the resolver signal of the drive motor. When the wheel slips, the drive motor needs to be controlled to reduce the 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 slips, the drive motor on the opposite side will also reduce the output torque.

[0037] According to the solution of the present application, when the wheels on both sides slip, the vehicle's yaw is suppressed through rapid perception of road adhesion and rapid adjustment of torque, and slipping will not occur on both sides, thereby improving the vehicle's controllability and safety.

[0038] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is further used to control the torques output by the two drive motors to be equal between the second moment and the third moment.

[0039] Between the second moment and the third moment, in order to suppress the yaw of the electric vehicle, the driving torque of the left and right wheels should be kept equal. At the same time, in order to suppress the slippage of the wheels on both sides, the reduction in the output torque of the drive motor should be selected on the side with the larger reduction of the drive motor on both sides. The greater the slip rate of the wheel, the greater the torque reduction required by the drive motor. The dual-motor controller can determine which side of the wheel has a larger slip rate based on the change in the speed of the drive motors on both sides within a preset time.

[0040] According to the solution of the present application, when the wheels on both sides slip, 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 through rapid perception of road adhesion and rapid adjustment of torque, thereby suppressing the vehicle's swaying and preventing slippage on both sides, thereby improving the vehicle's controllability and safety.

[0041] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is specifically used to control the torque output by the two drive motors to decrease at a preset rate of change or in a step-by-step manner between the second moment and the third moment.

[0042] Between the second moment and the third moment, the dual motor controller can control the torque to decrease in a step-by-step manner according to a certain gradient or according to a preset change rate when controlling the drive motor to reduce the torque. The preset change rate can be obtained through vehicle calibration or can be a preset value.

[0043] According to the solution of the present application, when the wheels slip, the dual-motor controller controls the drive motor torque output to be reduced at a fixed rate of change or in a step-by-step manner, which can effectively suppress slippage and reduce the sense of frustration, suppress vehicle sway, and improve vehicle safety and comfort.

[0044] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is specifically used to control the reduction in output torque of the two drive motors to be greater between the second moment and the third moment, when the greater the change in the rotational speed of at least one drive motor within a preset time period.

[0045] The dual-motor controller can obtain the speed of the drive motor through the resolver signal of the resolver sensor. The change rate of the drive motor speed or the change value of the speed within a preset time can reflect the change in adhesion between the wheel and the road to a certain extent. When the change rate of the drive motor is greater or the change value of the speed within a preset time is greater, it means that the road adhesion is reduced more. At this time, in order to control the wheel from slipping, the torque output of the drive motor needs to be reduced more.

[0046] According to the solution of the present application, the adhesion change of the oncoming road is quickly sensed by the change in the rotation speed of the drive motor to control the torque of the drive motor, keep the torque of the left and right wheels of the vehicle equal, suppress the sway of the vehicle, and improve driving safety.

[0047] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is specifically used to control the reduction amount of the output torque of the two drive motors to be greater when the driving torque of at least one wheel is smaller between the second moment and the third moment.

[0048] The dual-motor controller can calculate the actual output torque of the drive motor through the actual output current, and the actual output torque of the drive motor is proportional to the road adhesion. Therefore, when the output torque of the drive motor is smaller, the maximum adhesion of the road is smaller. In order to prevent the wheels from slipping, the output torque of the drive motor needs to be reduced more.

[0049] According to the solution of the present application, the adhesion change of the oncoming road is quickly sensed by the torque actually output by the driving motor to control the driving motor torque, keep the torque of the left and right wheels of the vehicle equal, suppress the vehicle's sway, and improve driving safety.

[0050] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is specifically used to control the two drive motors to reduce output torque more greatly between the second moment and the third moment, the greater the difference between the slip rate of at least one wheel and the preset slip rate.

[0051] The dual motor controller can obtain the rotation speed of the drive motor through the resolver signal of the resolver sensor. The angular velocity of the wheel can be calculated by the rotation speed of the drive motor and the transmission ratio of the electric vehicle. Therefore, the slip rate of each wheel can be obtained by combining the wheel radius and the speed of the electric vehicle. The slip rate in this application may refer to the slip rate. The wheels of the electric vehicle can obtain the maximum adhesion at the preset slip rate, so the electric vehicle can make full use of the road adhesion by controlling the slip rate of the wheel.

[0052] According to the solution of the present application, the adhesion change of the oncoming road is quickly sensed by the change of the wheel slip rate of the electric vehicle to control the torque of the drive motor, keep the torque of the left and right wheels of the vehicle equal, suppress the yaw of the vehicle, and improve driving safety.

[0053] In combination with the first aspect, in certain implementations of the first aspect, the dual-motor controller is specifically used to, between the second moment and the third moment, have the absolute value of the torque output by the two drive motors 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 be the same as the direction of the torque indicated by the torque signal.

[0054] In the process of controlling the torque reduction of the drive motor, the dual-motor controller needs to limit the torque finally output by the drive motor. The absolute maximum value of the torque finally output by 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.

[0055] According to the solution of the present application, in a scenario where an electric vehicle goes straight into an open road or starts on an open road, the torque of the left and right wheels of the vehicle is kept equal through rapid perception of road adhesion and rapid adjustment of torque, and the final torque is limited to not exceed the torque given by the current vehicle controller. Torque reversal is not allowed, vehicle yaw is suppressed, and driving safety is improved.

[0056] In a second aspect, the present application provides a control method for an electric vehicle, the control method being used to suppress the yaw of the electric vehicle during driving on an open road. The control method includes: at a first moment, the slip rates of the two coaxial wheels of the electric vehicle are both less than a preset slip rate, 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, the slip rate of at least one of the two wheels is greater than the preset slip rate, and the driving torque of the two wheels is actively controlled to be reduced.

[0057] In one implementation, an electric vehicle includes a plurality of motor controllers and a plurality of drive motors, wherein one motor controller is used to control one drive motor to output torque to drive or brake one wheel of the electric vehicle. Another motor controller is also used to control another drive motor to output torque to drive or brake another wheel of the electric vehicle. One wheel and another wheel are two front wheels or two rear wheels of the electric vehicle.

[0058] A motor controller is used to control a drive motor to reduce output torque in response to a change in the rotation speed of a drive motor of the electric vehicle within a preset time period being greater than a preset value during the driving or starting process of the electric vehicle. When the change in the rotation speed of a drive motor of the electric vehicle within a preset time period is less than or equal to a preset value, and the change in the rotation speed of another drive motor within a preset time period is greater than a preset value, the torque output by one drive motor is controlled to be reduced to be equal to the torque output by the other drive motor.

[0059] The motor controller can determine whether the wheel driven by the controlled drive motor is slipping through the resolver signal. If the wheel is not slipping, the drive motor is controlled to output the torque indicated by the torque signal. If the wheel is slipping, the torque output by the drive motor is reduced. If the opposite wheel is slipping, the torque output by the drive motor is controlled to be equal to the torque after the opposite drive motor is reduced.

[0060] The motor controller can determine whether the opposite wheel is slipping in a variety of ways. Exemplarily, the motor controller can be connected to the motor controller signal that controls the opposite drive motor, and obtain the change in the output torque of the opposite drive motor from the motor controller of the opposite drive motor. Exemplarily, the motor controller can be connected to the motor controller signal that controls the opposite drive motor, and obtain the slip rate of the opposite wheel from the motor controller of the opposite drive motor, and determine the value of the drive motor to reduce the torque based on the slip rates of the two wheels. Exemplarily, the motor controller can be connected to the opposite drive motor signal, and determine whether the opposite wheel is slipping based on the resolver signal.

[0061] In combination with the second aspect, in certain implementations of the second aspect, the control method further includes: at a third moment after the second moment, the slip rates of the two wheels are both less than or equal to the preset slip rate, controlling the driving torque of the two wheels to stop decreasing. After the third moment, controlling the driving torque of the two wheels to increase to the torque indicated by the accelerator pedal opening.

[0062] In combination with the second aspect, in certain implementations of the second aspect, the control method specifically includes: between the second moment and the third moment, controlling the driving torques of the two wheels to be equal.

[0063] A motor controller is used to control a drive motor to reduce output torque when the change value of the speed of a drive motor of the electric vehicle within a preset time period is greater than a preset value, and the change value of the speed of another drive motor within a preset time period is greater than a preset value and less than or equal to the change value of the speed of one drive motor within a preset time period during the driving or starting process of the electric vehicle. When the change value of the speed of a drive motor of the electric vehicle within a preset time period is greater than a preset value, and the change value of the speed of another drive motor within a preset time period is greater than a preset value and greater than the change value of the speed of one drive motor within a preset time period, one drive motor is controlled to reduce to a torque equal to that output by the other drive motor.

[0064] A motor controller is also used to control a drive motor to stop reducing output torque and increase output torque in the process of controlling a drive motor to reduce output torque, in response to a change in the speed of a drive motor indicated by a resolver sensor of the electric vehicle within a preset time period decreasing to less than or equal to a preset value.

[0065] A motor controller is also used to control a drive motor to stop reducing the output torque and increase the output torque when the change value of the speed of the other drive motor decreases to less than or equal to the preset value within a preset time period during the process of controlling the one drive motor to reduce the torque to be equal to the torque output by the other drive motor. When the slip characteristics of the opposite wheel disappear and the electric vehicle no longer slips, the motor controller can control the torque output by the drive motor to increase again.

[0066] In a third aspect, the present application provides an electric vehicle, which includes a dual motor controller, a vehicle controller and an accelerator pedal as described in the first aspect and various implementations thereof, wherein the vehicle controller is used to send a torque signal to the motor controller, and the torque signal is 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.

[0067] The beneficial effects of other aspects can refer to the beneficial effects described in the first aspect and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a schematic diagram of an electric vehicle entering a split road provided by an embodiment of the present application;

[0069] Figure 2 is a torque control schematic diagram provided in an embodiment of the present application;

[0070] Figure 3 is a schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0071] Figure 4is a schematic diagram of the architecture of an electric vehicle provided in an embodiment of the present application;

[0072] Figure 5 is a schematic diagram of a dual motor controller control provided by an embodiment of the present application;

[0073] Figure 6 is a schematic diagram of a yaw suppression control provided by an embodiment of the present application;

[0074] Figure 7 is a schematic diagram of a yaw control process provided by an embodiment of the present application;

[0075] Figure 8 is a schematic diagram of distributed drive motor control provided by an embodiment of the present application;

[0076] Fig. 9 is a schematic diagram of a yaw control process provided by an embodiment of the present application;

[0077] Fig.10 is a schematic diagram of a single drive motor architecture control provided by an embodiment of the present application;

[0078] Fig.11 is another schematic diagram of a yaw control process provided in an embodiment of the present application;

[0079] Fig.12 It is a schematic diagram of another yaw suppression control provided in an embodiment of the present application. DETAILED DESCRIPTION

[0080] The following will describe the technical solution in the present application in conjunction with the accompanying drawings. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0081] When a vehicle is driving straight and suddenly enters a split road or starts on a split road, the low-profile tires may lose grip earlier than the high-profile tires, causing the vehicle to sway sideways and affecting vehicle safety. Figure 1 As shown in (a), when an electric vehicle enters a split road in a regenerative mode, if the torques on both sides cannot be reduced quickly and simultaneously, the regenerative braking force on the high-attachment side will be greater than the regenerative braking force on the low-attachment side, and the vehicle will yaw toward the high-attachment side. Figure 1 As shown in (b), when an electric vehicle enters a split road or starts on a split road in a driving condition, if the torque on both sides cannot be quickly reduced at the same time, the traction on the high-attachment side will be greater than the traction on the low-attachment side, and the vehicle will yaw toward the low-attachment side. With the counterclockwise direction as the positive direction, the yaw moment of the vehicle can be expressed as:

[0082]

[0083] In formula (1), F fl 、F fr 、F rl 、F rr are the traction forces applied to the four wheels by the ground, and W is the wheel track.

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

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

[0086] When a vehicle is driving straight and suddenly enters a split road or starts on a split road, if the torque of the front and rear wheels on the low-adhesion side exceeds the adhesion limit of the road, F will occur. fl +F fr >F rl +F rr or F fl +F fr <F rl +F rr In the case of , according to formula (1), the vehicle will produce a large yaw, affecting driving safety.

[0087] In one possible implementation, Figure 2 As shown, traditional chassis control of automobiles is generally based on the ESP system. The ESP system determines whether the vehicle is skidding based on the relationship between wheel speed and vehicle speed. If the vehicle is skidding, the ESP system intervenes to implement torque intervention. The ESP system sends the adjusted torque to the vehicle controller, which transmits it to the motor controller, and finally achieves skidding control, making the torque of the wheels on the left and right sides 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 signal transmission link that needs to go through the transmission process from ESP to vehicle controller and then to motor controller, the vehicle control loop frequency is low, about 100Hz, and the signal transmission time is extended, and the entire control system has a delay of about 100ms. This will cause the wheels to fail to reduce torque in time when the car suddenly enters or starts on an open road, and the driving force of the low-end tire exceeds the road adhesion limit, causing the vehicle to yaw significantly, affecting driving safety.

[0089] Based on the above problems, the present application provides a dual-motor controller, control method and electric vehicle for suppressing yaw. When the electric vehicle enters or starts from an open road, if wheel slip occurs, the drive system quickly adjusts the output torque to reduce the torque of the wheels on the left and right sides at the same time, thereby suppressing the vehicle's yaw and improving the safety of the entire vehicle.

[0090] Figure 3 and Figure 4 Schematic diagram of an electric vehicle 10 provided in an embodiment of the present application.

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

[0092] It is understandable that the power battery in the embodiment of the present application can be a lithium-ion battery, a lithium metal battery, a lead-acid battery, a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-sulfur battery, a lithium-air battery or a sodium-ion battery, etc., and the present application does not limit this. The power battery can also power other electrical devices in the vehicle, such as the air conditioner in the vehicle, the car player, etc.

[0093] The electric vehicle 10 may be a distributed four-drive motor drive architecture, where the drive motors are arranged on the sides of the driven wheels and controlled by a separate motor controller 40. The electric vehicle 10 may also be a centralized drive motor drive architecture, where the drive motors for driving the two front wheels or the two rear wheels are arranged together, and the two drive motors are controlled by a dual motor controller 60. The motor controller 40 may be one or more. The motor controller 40 and the drive motor may correspond one to one, and one motor controller 40 may 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, if Figure 4As shown in (a), the electric vehicle 10 can be a distributed four-drive motor drive architecture, where the drive motors are arranged next to the driven wheels and controlled by a separate motor controller.

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

[0096] In one embodiment, if Figure 4 As shown in (b), the electric vehicle 10 may also be a centralized four-drive motor drive architecture, where two drive motors for driving two front wheels or two rear wheels are arranged together. The dual motor controller 60 is used to control the two drive motors arranged together.

[0097] Exemplarily, the electric vehicle 10 includes two dual-motor controllers, which include a dual-motor controller 61 and a dual-motor controller 62. The four motors include a drive motor 31, a drive motor 31, a drive motor 33, and a drive motor 34. The dual-motor controller 61 controls the drive motor 31 to drive the wheel 51, and controls the drive motor 32 to drive the wheel 52. The dual-motor controller 62 controls the drive motor 33 to drive the wheel 53, and controls the drive motor 34 to drive the wheel 54.

[0098] According to the position of the wheels, they can be divided into the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel. According to the axle, the left front wheel and the right front wheel are coaxial and connected by the front axle, and the left rear wheel and the right rear wheel are coaxial and connected by the rear axle. According to the position, the left front wheel and the left rear wheel are on the same side and located on the left side, and the right front wheel and the right rear wheel are on the same side and located on the right side. The two drive motors used to drive the two front wheels among the four drive motors are coaxial drive motors, and the two drive motors used to drive the two rear wheels are also coaxial drive motors.

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

[0100] In one embodiment, the various architectures mentioned above may 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 further 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, and the motor controller 40 or the dual motor controller 60 is connected to the vehicle controller 20 and other motor controllers 40 through the signal interface. The vehicle controller 20 is connected to the accelerator pedal signal, and the vehicle controller 20 calculates the vehicle torque demand according to the opening of the accelerator pedal during the driving process of the electric vehicle 10, and sends a torque signal to the motor controller 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 indication of the torque signal.

[0103] In one embodiment, each motor controller 40 or dual motor controller 60 may 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 through a signal interface, and the resolver sensor is used to detect the speed of the drive motor 30 controlled by the motor controller 40 or the dual motor controller 60, and the motor controller 40 is used to receive the signal from the resolver sensor. The motor controller 40 can also generate a speed signal based on the signal from the resolver sensor and send the speed signal to the other three motor controllers 40. Similarly, each motor controller 40 will also receive the speed signal 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 rotation speed of the drive motor. It has a high sampling rate and is directly connected to the motor controller 40, with short signal transmission time and higher stability.

[0106] In one embodiment, the motor controller 40 or the dual-motor controller 60 also obtains a vehicle speed signal from the vehicle controller 20 or other sensors of the electric vehicle 10 through a signal interface, and the vehicle speed signal is used to indicate the speed of the electric vehicle 10 .

[0107] Figure 5 The schematic diagram of the centralized four-drive motor architecture is shown below. Figure 6 and Figure 7 The working process of the dual-motor controller 60 for suppressing the lateral movement of the electric vehicle while driving on an open road provided in an embodiment of the present application is described.

[0108] Combination Figure 6 and Figure 7(a), from the first moment t1 to the second moment t2, the electric vehicle 10 is driving normally on a uniform road surface, the road surface contacted by the two wheels at the first moment t1 is a uniform road surface, and the difference in the adhesion coefficients of the two wheels on the uniform road surface is less than or equal to a preset difference. The dual motor controller 60 is specifically used for controlling the torque indicated by the output torque signal of the two drive motors when the slip rates of the two wheels are less than the preset slip rates at the first moment t1. The slip rates of the two wheels are less than the preset slip rates, and the wheels do not slip.

[0109] Combination Figure 6 and Figure 7 (b), at the second moment t2, the electric vehicle 10 enters the open road, and the road surface that the two wheels contact at the second moment t2 is the open road surface, and the difference in the adhesion coefficients of the two wheels on the open road surface is greater than the preset difference. Since the adhesion coefficients of the road surfaces contacted by the left and right wheels of the electric vehicle 10 are different, the road surface adhesion coefficient on one side is lower, and the wheel torque will break through the maximum adhesion of the road surface, the wheel will slip, and at this time the dual motor controller 60 is used to control the two drive motors to quickly reduce the torque so that the wheel can be restored from the slipping state to the non-slipping state. In addition, the dual motor controller 60 is used to control the two drive motors to quickly reduce the torque at the same time. If the torque reduction of the two motors is inconsistent, it will cause the left and right wheels of the vehicle to be unequally tractioned by the ground, the traction of the high adhesion side road surface is greater than the traction of the low adhesion side road surface, and the electric vehicle 10 will yaw to the low adhesion side. At the second moment t2, the dual motor controller 60 is also used to actively control the two drive motors 30 to reduce the torque output at the same time 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 the second moment t2, the slip rate of at least one of the two wheels is greater than the preset slip rate and the opening of the accelerator pedal of the electric vehicle increases, and 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 may also be referred to as an accelerator pedal or an acceleration pedal. The opening of the accelerator pedal can indicate the size of the driving force required by the driver. The larger the opening of the accelerator pedal, the greater the driver's demand for driving, and the corresponding torque required to be output by the drive motor is also greater. 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 according to the accelerator pedal opening. The larger the opening of the accelerator pedal, the greater the torque output by the drive motor 30, and the smaller the opening of the accelerator pedal, 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 of the opening of the accelerator pedal.

[0112] Continue reading Figure 6At the second moment t2, the wheel slips. At this time, the driver steps on 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 with the increase of the torque value indicated by the torque signal. Instead, the torque output by the two drive motors 30 is actively controlled to be reduced to a torque less than the torque indicated by the torque signal, thereby reducing the wheel slip. When the wheel slips, the dual motor controller 60 performs closed-loop control internally and no longer responds to the torque change indicated by the torque signal. When the wheel slips, the dual motor controller 60 quickly adjusts the torque internally, responds quickly, reduces the signal transmission time, and improves vehicle safety.

[0113] When the electric vehicle is driving normally, the dual-motor controller 60 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 10 suddenly enters an open road or starts on an open road, when the torque corresponding to the opening of the accelerator pedal indicated by the torque signal sent by the vehicle controller is greater than the maximum adhesion capacity of the tire on the open road, the dual-motor controller can quickly adjust the torque, and the dual-motor controller 60 controls the torque output by the two drive motors 30 to decrease and be less than the torque indicated by the torque signal. At this time, the torque output by the drive motor does not change with the change of the torque command or the opening of the accelerator pedal. According to the scheme of the present application, when the wheel slips, the dual-motor controller quickly adjusts the torque internally, which does not change with the change of the opening of the accelerator pedal, responds quickly, reduces the signal transmission time, and improves vehicle safety.

[0114] When the electric vehicle 10 enters the open road or starts on the open road in the feedback mode, the dual motor controller 60 controls the drive motor 30 to output reverse torque. When one wheel slips, the drive motor 30 used to drive the wheel needs to quickly reduce the torque. At the same time, the drive motor 30 on the other side needs to be controlled to quickly reduce the torque in coordination. Otherwise, the traction force on the left and right wheels of the vehicle will be unequal, and the braking force on the high-adhesion side will be greater than the braking force on the low-adhesion side. The electric vehicle 10 will yaw to the high-adhesion side. By quickly reducing the torque on the left and right wheels at the same time, the vehicle yaw is suppressed.

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

[0116] In addition, the dual-motor controller 60 provided in the embodiment of the present application can actively control the two drive motors 30 to reduce the torque output at the same time. 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 the torque output at the same time, and will no longer control the two drive motors 30 for torque output according to the torque indicated by the torque signal output by the vehicle controller 20.

[0117] See Figure 6 , between the first moment t1 and the second moment t2, the wheel does not slip, and the two drive motors 30 are controlled to output torque according to the torque indicated by the torque signal output by the vehicle controller. At the second moment t2, the wheel slips, and between the second moment t2 and the third moment t3, the dual-motor controller 60 will actively adjust the two drive motors 30 to reduce the torque output at the same time, and no longer control the two drive motors 30 to output torque according to the torque indicated by the torque signal output by the vehicle controller. At the third moment t3, when the slip signal feature of the drive motor speed signal disappears, the drive motor torque of the electric vehicle 10 is restored at a certain gradient, but will not exceed the torque indicated by the vehicle controller 20. That is to say, the dual-motor controller 60 provided in the embodiment of the present application realizes the internal closed-loop active control of the torque of the dual-motor controller 60 under the condition of wheel slippage, and no longer outputs torque according to the instruction of the vehicle controller, thereby shortening the control link and improving the control accuracy and control rate.

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

[0119] Combination Figure 6, at the second moment t2, when the electric vehicle 10 starts on the open road or passes through the open road during driving, due to the different road adhesion coefficients of the left and right wheels of the electric vehicle 10, the road adhesion coefficient on one side is lower, and the wheel torque will break through the maximum adhesion of the road surface, the wheel will slip, the wheel speed will suddenly rise or fall, and the speed change of the wheel will also quickly react to the speed of the drive motor 30. The speed of the drive motor 30 can be detected by a rotary sensor. The rotary sensor can accurately detect the position, direction and speed of the drive motor rotor, and is responsible for monitoring and extracting the rotation speed of the drive motor. It has high sampling frequency and accuracy, and is directly connected to the dual motor controller 60. The signal transmission time is short and the stability is higher. When the speed of a drive motor indicated by the rotary sensor of the electric vehicle 10 changes by more than the preset value within a preset time length, the speed of a wheel driven by the drive motor changes suddenly. When the drive motor outputs positive torque, the change value within the preset time length is an increase value, and when the drive motor outputs reverse torque, the change value within the preset time length is a decrease value.

[0120] The dual motor controller 60 determines whether the wheel driven by the drive motor 30 is slipping according to the rotation signal of the drive motor 30. When the wheel is slipping, the drive motor 30 needs to be controlled to reduce the 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 the output torque.

[0121] When the electric vehicle 10 suddenly goes straight into an open road or starts on an open road, the traditional chassis control system will cause the electric vehicle 10 to yaw greatly due to its slow control. The drive motor 30 is connected to the wheel through a half shaft, so when the wheel torque exceeds the maximum adhesion of the road surface, the wheel speed will suddenly rise (drive) or fall (feedback or braking), and the wheel speed change will quickly react to the speed of the drive motor 30. The rotary variable sensor of the drive motor 30 has the characteristics of fast perception, low latency, and high precision. 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, and then quickly adjust the torque according to the identified road surface adhesion, so that the traction of the left and right wheels of the vehicle is consistent, thereby achieving fast control and high-precision control.

[0122] In one embodiment, between the second moment t2 and the third moment 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 that the dual-motor controller 60 is specifically used to control.

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

[0124] In one embodiment, between the second moment t2 and the third moment t3, 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 30 controlled by the dual motor controller 60.

[0125] Combination Figure 6 , between the first moment t1 and the second moment t2, in the process of the dual-motor controller 60 controlling the two drive motors 30 to reduce the torque output, the reduction amount of the torque output controlled by the dual-motor controller 60 can be determined according to the change value of the speed of the drive motor 30 within a preset time length, the driving torque of a wheel, or the difference between the slip rate of a wheel and the preset slip rate.

[0126] The dual motor controller 60 can obtain the rotation speed of the drive motor 30 through the resolver signal of the resolver sensor. The change rate of the rotation speed of the drive motor 30 or the change value of the rotation speed within a preset time period can reflect the change of adhesion between the wheel and the road surface to a certain extent. When the change rate of the drive motor 30 is greater or the change value of the rotation speed within a preset time period is greater, it means that the road adhesion is reduced more. At this time, in order to control the wheel from slipping, it is necessary to reduce the torque output by the drive motor more, so as to suppress the slipping 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 through the actual output current, and the actual output torque of the drive motor is proportional to the road adhesion. Therefore, when the output torque of the drive motor is smaller, the maximum road adhesion is smaller, and in order to prevent the wheels from slipping, the output torque of the drive motor needs to be reduced more.

[0128] The dual motor controller 60 can obtain the rotation speed of the drive motor 30 through the resolver signal of the resolver sensor. The angular velocity of the wheel can be calculated by the rotation speed of the drive motor 30 and the transmission ratio of the electric vehicle 10. Therefore, the slip rate of each wheel can be obtained by combining the wheel radius and the speed of the electric vehicle. In this application, the slip rate may refer to the slip rate. The wheels of the electric vehicle can obtain the maximum adhesion at the preset slip rate, so the electric vehicle can make full use of the road adhesion by controlling the slip rate of the wheel.

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

[0130] Combination Figure 6, between the second moment t2 and the third moment t3, in the process of the dual-motor controller 60 controlling the two drive motors 30 to reduce the torque output, the dual-motor controller 60 controls the two drive motors 30 to reduce the torque output by an equal amount, thereby ensuring that the driving torque of the left and right wheels should remain equal, thereby avoiding the electric vehicle 10 from swaying due to the different driving torques of the left and right wheels, thereby improving the safety and reliability of the electric vehicle 10.

[0131] At the same time, in order to suppress the slipping of the wheels on both sides, the reduction amount of the output torque of the drive motor 30 should be selected from the side with the larger reduction amount of the drive motor 30 on both sides. The larger the slip rate of the wheel, the larger the torque reduction amplitude of the drive motor. The dual motor controller 60 can determine which side of the wheel has the larger slip rate according to the change value of the rotation speed of the drive motors on both sides within a preset time length.

[0132] The vehicle controller 20 sends a torque command to the dual-motor controller 60 according to the driver's intention. The sent torque first passes through the road adhesion recognition and torque adjustment module, which recognizes the maximum adhesion capacity of the road according to the rotational signal of the drive motor 301 and the drive motor 302. If the torque command is greater than the maximum adhesion capacity of the road, the torque command of the drive motor 301 and the drive motor 302 is quickly adjusted and finally output to the drive motor 301 and the drive motor 302, so that the traction force of the left and right wheels of the vehicle is the same, and finally the vehicle yaw suppression is achieved.

[0133] In one embodiment, between the second moment t2 and the third moment 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 step-by-step manner.

[0134] Combination Figure 6 , between the second moment t2 and the third moment t3, when the dual motor controller 60 controls the two drive motors 30 to reduce the torque output, the torque can be controlled to be reduced in a step-by-step manner according to a certain gradient, or to be reduced according to a preset change rate. The preset change rate can be obtained by vehicle calibration or can be a preset value.

[0135] According to the solution of the present application, when the wheel slips, the dual-motor controller 60 controls the drive motor torque output to be reduced at a fixed rate of change or in a step-by-step manner, so that the torque output by the drive motor 30 can be slowly reduced, which can effectively suppress slippage and reduce the sense of frustration, suppress vehicle sway, and improve vehicle safety and comfort.

[0136] In one embodiment, between the second moment t2 and the third moment 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] In the process of controlling the torque reduction of the drive motor 30, the dual-motor controller 60 needs to limit the torque finally output by the drive motor 30. The maximum absolute value of the torque finally output by 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 of the present application, in a scenario where an electric vehicle goes straight into an open road or starts on an open road, the torque of the left and right wheels of the vehicle is kept equal through rapid perception of road adhesion and rapid adjustment of torque, and the final torque is limited to not exceed the torque given by the current vehicle controller. Torque reversal is not allowed, vehicle yaw is suppressed, and driving safety is improved.

[0139] Combination Figure 6 and Figure 7 (c), at the third moment t3, the electric vehicle 10 leaves the open road, the road surface contacted by the two wheels at the third moment t3 is a uniform road surface, and the difference in 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 moment t3 after the second moment t2 when the slip rates of the two wheels are less than or equal to the preset slip rate.

[0140] In one embodiment, after the third moment t3, the dual-motor controller 60 is further 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 moment t3, when the slip signal characteristic of the driving motor speed signal of the electric vehicle 10 disappears, that is, when the slip rate of the two wheels is less than the preset slip rate, the dual motor controller 60 controls the two driving motors 30 to output the driving motor torque according to the torque indicated by the torque signal output by the vehicle controller. In other words, the dual motor controller 60 will control the torque value output by the two driving motors 30 to increase to the torque value indicated by the torque signal. After the third moment t3, the electric vehicle 10 runs normally. At this time, the torque value indicated by the torque signal increases, and the dual motor controller 60 will actively control the torque output by the two driving motors 30 to increase to the torque indicated by the torque signal. After the third moment t3, when the torque value indicated by the torque signal increases, the torque output by the two driving motors 30 controlled by the dual motor controller 60 will also increase with the increase of the torque value indicated by the torque signal.

[0142] In the embodiment of the present application, when the wheels are not slipping, the drive motor is controlled to output the torque indicated by the torque signal, without reducing 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 a 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 driving on the open road is similar to the working process of the aforementioned dual-motor controller 60. Some differences are briefly described below. The specific process can also be referred to Figure 6 and Figure 7 .

[0144] The motor controller 40 provided in the implementation of the present application may be any one of a plurality of motor controllers. The following embodiments only take any one of the motor controllers 40 as an example, and the actions of other motor controllers may be similarly understood by referring to the description.

[0145] like Figure 8 As shown, the electric vehicle 10 includes a plurality of motor controllers 40 and a plurality of drive motors 30. Among them, one motor controller 401 is used to control a drive motor 301 to output torque to drive or brake the electric vehicle, and another motor controller is used to control another drive motor 302 to output torque to drive or brake the electric vehicle. One drive motor 301 and another drive motor 302 are used to drive the two front wheels or the two rear wheels of the electric vehicle 10 respectively. The left and right drive motors 30 at the single shaft are controlled separately, and the torque of the left and right drive motors 30 can be independently controlled, and the left and right two-wheel electric drive system communicates in real time through the controller area network (CAN) bus or other forms.

[0146] At the second moment t2, the change value of the rotation speed of a driving 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 a driving motor 301 to reduce the output torque.

[0147] In one embodiment, at the second moment t2, when the change value of the rotational speed of one drive motor 301 of the electric vehicle 10 within a preset time length is less than or equal to a preset value, and the change value of the rotational speed of another drive motor 302 within a preset time length is greater than a preset value, the torque output by one drive motor 301 is controlled 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 via CAN or universal asynchronous receiver / transmitter (UART), etc. The left and right motor controllers communicate in real time and transmit the torque adjustment of the current drive motor to the opposite motor controller via CAN or other communication methods.

[0149] When the electric vehicle 10 starts on a split road or passes through a split road during driving, due to the different road adhesion coefficients of the left and right wheels of the electric vehicle 10, the road adhesion coefficient on one side is lower, and the wheel torque will break through the maximum adhesion of the road surface, the wheel will slip, the wheel speed will suddenly rise or fall, and the speed change of the wheel will also quickly react to the speed of the drive motor. The speed of the drive motor 30 can be detected by a rotary sensor. The rotary sensor can accurately detect the position, direction and speed of the drive motor rotor, is responsible for monitoring and extracting the rotation speed of the drive motor, has a high sampling rate, and is directly connected to the motor controller, has a short signal transmission time, and has higher stability. When the speed of a drive motor 301 indicated by the rotary sensor of the electric vehicle 10 changes within a preset time period and the change value is greater than the preset value, the speed of a wheel driven by the drive motor 301 changes suddenly. When the drive motor outputs positive torque, the change value within the preset time period is an increase value, and when the drive motor outputs reverse torque, the change value within the preset time period is a decrease value.

[0150] For an electric vehicle 10 with a distributed drive motor, when the electric vehicle 10 enters an open road in a driving state or starts on an open road, the motor controller 40 controls the drive motor 30 to output positive torque, and the speed of the drive motor 30 used to drive the wheels on the low-adhesion side road suddenly increases. At this time, the drive motor 30 needs to reduce the torque quickly, otherwise the wheels on the low-adhesion 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 the torque in coordination, otherwise the traction force on the left and right wheels of the vehicle will be unequal, the traction force on the high-adhesion side road is greater than the traction force on the low-adhesion side road, and the electric vehicle 10 will yaw to the low-adhesion side. When the electric vehicle 10 enters the open road or starts on the open road in the feedback mode, the motor controller 40 controls the drive motor 30 to output reverse torque, and the speed of the drive motor 30 used to drive the wheel on the low-adhesion side road suddenly decreases. At this time, the drive motor 30 needs to quickly reduce the torque. At the same time, it is also necessary to control the drive motor 30 on the other side to quickly reduce the torque in coordination. Otherwise, the traction force on the left and right wheels of the vehicle will be unequal, and the braking force on the high-adhesion side road will be greater than the braking force on the low-adhesion side road, and the electric vehicle 10 will yaw to the high-adhesion side. By quickly reducing the torque on the left and right wheels at the same time, the vehicle yaw is suppressed.

[0151] In one embodiment, at the second moment t2, when the change value of the rotation speed of one drive motor 301 of the electric vehicle within the preset time length is greater than the preset value, and the change value of the rotation speed of another drive motor 302 within the preset time length is greater than the preset value and less than or equal to the change value of the rotation speed of one drive motor 301 within the preset time length, a motor controller 401 is used to control one drive motor 301 to reduce the output torque. When the change value of the rotation speed of one drive motor 301 of the electric vehicle 10 within the preset time length is greater than the preset value, and the change value of the rotation speed of another drive motor 302 within the preset time length is greater than the preset value and greater than the change value of the rotation speed of one drive motor 301 within the preset time length, one drive motor 301 is controlled to be reduced to be equal to the torque output by the other drive motor 302.

[0152] The motor controller 40 determines whether the wheel driven by the drive motor 30 is slipping according to the rotation signal of the drive motor 30. When the wheel is slipping, the drive motor needs to be controlled to reduce the output torque. At the same time, 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 the opposite side will also reduce the output torque. In order to suppress the vehicle yaw, the output torque reduced by the drive motors 30 on both sides should be consistent.

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

[0154] In one embodiment, at the third moment t3, a motor controller 401 is used to control 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] In the process of reducing torque, when the change value of the rotation speed of the drive motor 30 within the preset time length is reduced to less than or equal to the preset value, the wheel slip feature disappears, the electric vehicle 10 no longer slips, and the torque output by the drive motor 30 can be gradually increased in a step-by-step manner or at a preset rate of change, and gradually restored to the torque indicated by the opening of the accelerator pedal. Increasing the torque in a step-by-step manner or at a preset rate of change can maintain the stability of the electric vehicle 10.

[0156] In one embodiment, at the third moment t3, when the rotation speed of another drive motor 302 changes within a preset time period to less than or equal to a preset value, a motor controller 401 is also used to control a drive motor 301 to stop reducing the output torque and increase the output torque.

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

[0158] The present application provides a control method for an electric vehicle. Figure 6 and Figure 7 , the control method provided in this application is described.

[0159] In one embodiment, the control method includes: at a first moment t1, the slip rates of the two coaxial wheels of the electric vehicle 10 are both less than a preset slip rate, 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 t2 after the first moment t1, the slip rate of at least one of the two wheels is greater than the preset slip rate, and the driving torque of the two wheels is actively controlled to be reduced.

[0160] Combination Figure 6 and Figure 7 , from the first moment t1 to the second moment t2, the electric vehicle 10 is driving normally on a uniform road surface, the slip rates of the two wheels are less than the preset slip rates, the wheels do not slip, and the driving torque of the two coaxial wheels of the electric vehicle is controlled to be the torque indicated by the accelerator pedal opening of the electric vehicle. At the second moment t2 after the first moment t1, the electric vehicle 10 is driving into a split road surface. Since the road adhesion coefficients of the left and right wheels of the electric vehicle 10 are different, the road adhesion coefficient on one side is lower, and the wheel torque will break through the maximum adhesion of the road surface, the wheel will slip. At this time, the two drive motors are controlled to quickly reduce the torque so that the wheels can recover from the slipping state to the non-slipping state, so that the electric vehicle can continue to drive safely. The control method provided in the embodiment of the present application can quickly reduce the driving torque when the wheels of the electric vehicle 10 slip, so that the wheels of the electric vehicle 10 can quickly recover from the slipping state to the non-slipping state, thereby improving the driving safety of the electric vehicle.

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

[0162] Continue to participate Figure 6, between the second moment t2 and the third moment t3, the two drive motors 30 are actively controlled to reduce the torque output at the same time, and the two drive motors 30 are no longer controlled to output torque according to the torque indicated by the torque signal output by the vehicle controller. At the third moment t3, after the slip rate of the two wheels is less than the preset slip rate, the wheel slip disappears at this time, so it is necessary to control the two drive motors to stop reducing the torque output and control the torque of the two drive torque outputs to increase, so that the electric vehicle 10 returns to a normal driving state. However, in the process of controlling the torque increase of the two drive torque outputs, the torque of the two drive torque outputs is controlled not to be greater than the torque indicated by the accelerator pedal opening. Preferably, the torque of the two drive torque outputs is controlled to be equal to the torque indicated by the accelerator pedal opening, so as to control the electric vehicle 10 to respond to the driver's operation of the accelerator pedal, thereby improving the driving performance and power of the vehicle.

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

[0164] Combination Figure 6 Between the second moment t2 and the third moment t3, in the process of controlling the two drive motors 30 to reduce the torque output, the two drive motors 30 are controlled to reduce the torque output by an equal amount so as to ensure that the driving torques of the left and right wheels remain equal, thereby avoiding the electric vehicle 10 from swaying due to the different driving torques of the left and right wheels, thereby improving the safety and reliability of the electric vehicle 10.

[0165] like Fig. 9 As shown, for electric vehicles with distributed drive motors or centralized drive motor architectures, the overall control process is as follows:

[0166] The vehicle controller 20 sends torque instructions of 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 according to the rotation signal of the drive motor 30. If the wheel is slipping, the torque of the drive motor 30 on this side is reduced with a fixed gradient, and the torque adjustment amount △T1 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 with a certain gradient to the torque given by the vehicle controller 20, that is, the torque adjustment amount △T1 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 amount is taken as the current drive motor torque adjustment amount and the opposite drive motor torque adjustment amount, whichever has a larger absolute value. If the opposite drive motor 30 is not slipping, the final drive motor 30 torque adjustment amount is taken as the current drive motor torque adjustment amount ΔT1.

[0169] The final torque of the drive motor 30 is limited, and the maximum absolute value cannot exceed the torque indicated by the torque signal of the current vehicle controller 20, and the torque is not allowed to be reversed. The torque adjustment amount of the drive motors on both sides is the one with the larger absolute value, so that the drive motors on both sides can reduce the torque at the same time, and the wheels on both sides can produce torque with low adhesion to the road surface, eliminate the yaw moment, and suppress the yaw of the vehicle.

[0170] Taking the electric vehicle 10 starting at full throttle on a split road, with the left side of the vehicle being a low-adhesion road and the right side being a high-adhesion road as an example, the control result of the split road yaw suppression of the electric vehicle 10 is as follows: Figure 6 shown.

[0171] Fig.10 Schematic diagram of an electric vehicle with a single motor drive architecture. For an architecture in which a single drive motor drives two coaxial wheels, the electric vehicle 10 drives two front wheels or two rear wheels of the electric vehicle simultaneously through the drive motor 30. The drive motor 30 is connected to the left and right wheels through a mechanical differential. The torque transmitted by the drive motor to the left and right wheels is the same. Therefore, reducing the torque output by the drive motor 30 can simultaneously reduce the torque received by the left and right wheels.

[0172] The electric vehicle 10 drives the two front wheels or the two rear wheels of the electric vehicle at the same time through the drive motor 30. The drive motor 30 is connected to the left and right wheels through a mechanical differential, and the torque transmitted to the left and right wheels by the drive motor is the same, so reducing the torque output by the drive motor 30 can achieve the simultaneous reduction of the torque received by the left and right wheels.

[0173] When the vehicle suddenly goes straight into an oncoming road or starts on an oncoming road, the motor controller 40 determines at a frequency of 1000 Hz that the wheels are slipping. The drive motor quickly reduces the torque of the left and right wheels at the same time based on the torque command of the vehicle controller 20 to suppress wheel slippage. When the road adhesion is restored, the torque of the left and right wheels is restored to the torque command of the vehicle controller 20 with a certain gradient. During the whole process, the absolute value of the torque of the drive motor 30 does not exceed the torque command of the vehicle controller 20.

[0174] like Fig.11 As shown, for an electric vehicle 10 with a single drive motor, the overall control process is as follows:

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

[0176] The motor controller 40 determines whether the wheel is slipping according to the rotation signal of 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 to the torque given by the vehicle controller 20, that is, 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 be reversed.

[0177] Taking the electric vehicle 10 starting at full throttle on a split road, with the left side of the vehicle being a low-adhesion road and the right side being a high-adhesion road as an example, the control result of the split yaw suppression of the electric vehicle 10 with a single drive motor architecture is as follows: Fig.12 shown.

[0178] The electric vehicle 10 runs normally from the first moment to the second moment, and the wheels do not slip. When the electric vehicle 10 enters an oncoming road or starts on an oncoming road at the second moment, when the torque indicated by the torque signal sent by the vehicle controller 20 is greater than the low-attachment road adhesion, the motor controller 40 identifies the road adhesion capacity of the low-attachment road according to the rotary transformer signal, and outputs a compensating torque to make the drive motor torque at the maximum adhesion capacity of the road, and the vehicle will not yaw. At the third moment, when the slip signal feature of the drive motor speed signal of the electric vehicle 10 disappears, the drive motor torque is restored at a certain gradient, but will not exceed the torque indicated by the vehicle controller 20. Fig.12 It can be seen that the front and rear drive motors are independently adjusted, and both can output motor torque with maximum road adhesion, and the vehicle will not sway.

[0179] According to the solution of the present application, when an electric vehicle goes straight into an open road or starts on an open road, the torque of the left and right wheels of the vehicle is kept equal through rapid perception of road adhesion and rapid adjustment of torque, thereby suppressing vehicle sway and improving driving safety.

[0180] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A dual motor controller, characterized in that: The dual-motor controller is used to suppress the yaw of the electric vehicle during driving on an open road, and the dual-motor controller is used to control the output torque of the two drive motors to respectively drive the two coaxial wheels of the electric vehicle; The dual motor controller is specifically used for: At a first moment, the slip rates of the two wheels are both less than a preset slip rate, and the two drive motors are controlled to output torques indicated by the torque signals; At a second moment after the first moment, the slip rate of at least one of the two wheels is greater than a preset slip rate, and the two drive motors are actively controlled to reduce torque output at the same time.

2. The dual motor controller according to claim 1, characterized in that: The road surface contacted by the two wheels at the first moment is a uniform road surface, and the road surface contacted by the two wheels at the second moment is an open road surface; The difference in adhesion coefficients of the two wheels on the uniform road surface is less than or equal to a preset difference, and the difference in adhesion coefficients of the two wheels on the split road surface is greater than a preset difference.

3. The dual motor controller according to claim 1 or 2, characterized in that: The dual motor controller is also used for: At the second moment, the two drive motors are actively controlled to simultaneously reduce 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 according to any one of claims 1 to 3, characterized in that: The dual motor controller is also used for: At a third moment after the second moment, the slip rates of the two wheels are both less than or equal to the preset slip rate, and the torque output by the two drive motors is controlled to stop decreasing.

5. The dual motor controller according to claim 4, characterized in that: The dual motor controller is also used for: After the third moment, the torque output by the two driving motors is controlled to increase to the torque indicated by the torque signal.

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

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

8. The dual motor controller according to claim 4, characterized in that: The dual motor controller is also used for: Between the second moment and the third moment, the torques output by the two drive motors are controlled to be equal.

9. The dual motor controller according to claim 4, characterized in that: The dual motor controller is specifically used for: Between the second moment and the third moment, the torque output by the two driving motors is controlled to decrease at a preset change rate or in a step-by-step manner.

10. The dual motor controller according to claim 4, characterized in that: The dual motor controller is specifically used for: Between the second moment and the third moment, the greater the change in the rotation speed of the at least one drive motor within the preset time period, the greater the reduction in the output torque of the two drive motors is controlled.

11. The dual motor controller according to claim 4, characterized in that: The dual motor controller is specifically used for: Between the second moment and the third moment, the greater the difference between the slip rate of the at least one wheel and the preset slip rate, the greater the reduction amount of the output torque of the two driving motors is controlled to be.

12. A control method for an electric vehicle, characterized in that: The control method is used to suppress the swaying of the electric vehicle during driving on an open road, and the control method includes: At a first moment, the slip rates of the two coaxial wheels of the electric vehicle are both less than a preset slip rate, 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, the slip rate of at least one of the two wheels is greater than a preset slip rate, and the driving torque of the two wheels is actively controlled to be reduced.

13. The control method according to claim 12, characterized in that: The control method further comprises: At a third moment after the second moment, the slip rates of the two wheels are both less than or equal to the preset slip rate, 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 controlled to increase to the torque indicated by the accelerator pedal opening.

14. The control method according to claim 13, characterized in that: The control method specifically includes: Between the second moment and the third moment, the driving torques of the two wheels are controlled to be equal.

15. An electric vehicle, characterized in that: The electric vehicle includes a dual-motor controller, a vehicle controller and an accelerator pedal as described in any one of claims 1 to 11, the vehicle controller is used to send a torque signal to the dual-motor controller, and the torque signal is 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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