Control methods for electric vehicles, vehicle controllers, and electric vehicles

Abstract

A control method for electric vehicles, a vehicle controller, and an electric vehicle are disclosed, relating to the field of new energy vehicles and applicable to pure electric vehicles and hybrid vehicles. The control method assists the electric vehicle in drifting by controlling its distributed drive system and steering system after the drift mode is activated. The method includes controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel after the accelerator pedal opening is greater than a first preset opening and the steering wheel is turned to the left by an angle greater than a first preset angle, but before the steering wheel is turned to the right by an angle greater than zero. When the steering wheel is turned to the right by an angle greater than zero and less than a second preset angle, the speed of the right rear motor driving the right rear wheel is controlled to be less than the speed of the left rear motor driving the left rear wheel. According to this solution, the skill requirements for drifting operations are reduced, improving the driving experience and safety of the vehicle.

Description

Technical Field

[0001] This application relates to the field of new energy vehicles, and more specifically, to a control method for electric vehicles, a vehicle controller, and an electric vehicle. Background Technology

[0002] Drifting is a car driving technique commonly used in racing or performances. Drifting occurs when some of the vehicle's tires lose traction, causing the vehicle to turn at a large sideslip angle. Drivers can perform drifts by manipulating the drive, brakes, and steering wheel to achieve small-radius turns, catering to the needs of racing, driving pleasure, and maneuvering in tight spaces.

[0003] However, drifting typically requires a driver with proficient driving skills and precise timing, demanding advanced drifting techniques that are difficult for ordinary drivers to achieve. Currently, for electric vehicles with distributed motors, assisted drifting solutions still face challenges such as high driving difficulty, leading to the vehicle easily fishtailing or failing to maintain a drift.

[0004] Therefore, how to make it easier for electric vehicles to drift and maintain drifting is a problem that needs to be solved. Summary of the Invention

[0005] This application provides a control method for electric vehicles, including a vehicle controller and an electric vehicle. When the electric vehicle is drifting, the distributed drive system actively adjusts the rotational speed of the two rear wheels, enabling the electric vehicle to quickly enter a tail-swing state and maintain the drifting trend. This reduces the skill requirements of the driver for drifting operations, reduces the risk of drift loss of control, and improves the driving experience and safety of the vehicle.

[0006] Firstly, this application provides a control method for an electric vehicle. During the operation of the electric vehicle, the control method assists the electric vehicle in drifting by controlling its distributed drive system and steering system after the drift mode is activated. The control method includes controlling the rotational speed of the right rear motor driving the right rear wheel to be greater than the rotational speed of the left rear motor driving the left rear wheel after the accelerator pedal opening is greater than a first preset opening and the steering wheel turns to the left at an angle greater than a first preset angle, but before the steering wheel turns to the right at an angle greater than zero. When the steering wheel turns to the right at an angle greater than zero and less than a second preset angle, the rotational speed of the right rear motor driving the right rear wheel is controlled to be less than the rotational speed of the left rear motor driving the left rear wheel.

[0007] Electric vehicles are equipped with a drift mode. Once activated, the driver determines whether to initiate a drift based on the accelerator pedal position and steering wheel angle. Drifting is a special driving technique that involves causing the rear wheels to lose or significantly reduce traction while turning, resulting in oversteer, the rear end swinging outwards, and the vehicle sliding into a turn. This process requires a high level of skill from the driver and a sensitive ability to coordinate the steering wheel, accelerator, and brakes to effectively control the vehicle's dynamics.

[0008] A distributed drive system refers to a drive system in which each or more drive wheels of an electric vehicle are independently equipped with a drive motor, and each motor independently controls the torque and speed of each wheel. For electric vehicles with a distributed drive system, driving the wheels with multiple motors can effectively reduce or eliminate the lateral adhesion of the tires, enabling drifting. However, it is difficult for the driver to accurately complete a drift by operating the steering wheel and the distributed drive system. The control method for electric vehicles provided in this application can assist the driver in drifting. During the driver's drifting operation, an algorithm assists the driver in control, making it easier for the electric vehicle to enter a drift state and less likely to exit it.

[0009] The accelerator pedal in this application can also be referred to as the power pedal or accelerator pedal. The opening degree of the accelerator pedal indicates the amount of driving force required by the driver. The larger the opening degree of the accelerator pedal, the greater the driver's demand for driving force, and the greater the torque required from the drive motor. When drifting is not performed, the motor controller controls the drive motor to output the torque indicated by the accelerator pedal opening degree. The larger the accelerator pedal opening degree, the greater the torque output by the drive motor; the smaller the accelerator pedal opening degree, the smaller the torque output by the drive motor. The torque output by the drive motor varies with the opening degree of the accelerator pedal.

[0010] When the electric vehicle's drift mode is activated, the driver depresses the accelerator pedal and simultaneously turns the steering wheel sharply. Once the accelerator pedal opening exceeds a first preset opening and the steering wheel is turned to the left by a greater than a first preset angle, the electric vehicle determines the driver's intention to drift based on these parameters. It then controls the right rear motor to drive the right rear wheel at a higher speed than the left rear motor to drive the left rear wheel. Specifically, the right rear motor drives the right rear wheel, and the left rear motor drives the left rear wheel. The driver's desired torque is identified by the accelerator pedal opening and converted into an increment in motor speed. Upon recognizing the driver's drift intention, the rear axle motor speed is adjusted to initiate a drift state. By actively controlling the right rear wheel speed to exceed the left rear wheel speed, the two rear wheels of the electric vehicle break traction and begin to slip. The front wheels turn to one side, generating a sideslip angle and lateral force. The speed difference between the two rear wheels causes a leftward yaw rate, and the electric vehicle quickly enters a fishtailing state.

[0011] In a drift state, the rear of the electric vehicle swings outwards. Without correction, the vehicle will continue to spin or even turn around. Once the electric vehicle reaches the drift equilibrium point, correction is needed. The driver counter-steers in the opposite direction of the drift, causing the front wheels to point in the actual direction of travel. This balances the rotational torque generated by the sideslip of the two rear wheels, maintaining a controllable sideslip. When the steering wheel is turned to the right at an angle greater than zero and less than a second preset angle (i.e., in a drift state with the steering wheel turned counter-steer), the speed at which the right rear motor drives the right rear wheel is less than the speed at which the left rear motor drives the left rear wheel. During the drift stabilization phase, to maintain the electric vehicle's drift and prevent loss of control, the speed difference between the two rear wheel motors is adjusted, thus maintaining the yaw rate and sideslip state.

[0012] It should be understood that the first preset opening, the first preset angle, and the second preset angle are pre-calibrated based on actual vehicle experiments and / or model calculations, or they can be pre-set by comprehensively considering the needs of the whole vehicle and the vehicle performance.

[0013] It should be understood that this application uses drifting with the steering wheel turned to the left as an example for illustration. When drifting with the steering wheel turned to the right, the control method can be modified accordingly. For example, after the accelerator pedal opening of the electric vehicle is greater than a first preset opening and the angle of the steering wheel turning to the right is greater than a first preset angle, but before the angle of the steering wheel turning to the left is greater than zero, the speed at which the left rear motor drives the left rear wheel is controlled to be greater than the speed at which the right rear motor drives the right rear wheel. When the angle of the steering wheel turning to the left is greater than zero and less than a second preset angle, the speed at which the left rear motor drives the left rear wheel is controlled to be less than the speed at which the right rear motor drives the right rear wheel. The same modifications can be made for drifting with the steering wheel turned to the right, and will not be elaborated further below.

[0014] According to the solution in this application, when an electric vehicle is drifting, the driver's drifting intention is recognized by the accelerator pedal and steering wheel to control the vehicle into a drifting state. The torque desired by the driver is converted into an increment of motor speed, and the target speed of the rear axle motor is corrected. This makes it easier for the electric vehicle to drift, reduces the probability of the vehicle losing control or exiting the drift due to driver misoperation, enables the vehicle to drift stably, reduces the skill requirements of the driver for drifting operations, and improves the driving experience and safety of the vehicle.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the control method further includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, before the steering wheel turns to the right at an angle greater than zero, controlling the speed of the left front motor driving the left front wheel to increase and controlling the speed of the right front motor driving the right front wheel to decrease.

[0016] Existing drift-assisted technologies typically put the vehicle in a pure rear-wheel-drive state, and the counter-drift still relies on the driver to operate the steering wheel, which is quite difficult to operate. Novice drivers cannot accurately grasp the timing and speed of the counter-steering, which can easily lead to loss of control or inability to maintain the drift.

[0017] Once an electric vehicle enters its drift equilibrium point, it needs to counter-steer to correct the direction, so that the front wheels point in the actual driving direction and balance the rotational torque generated by the sideslip of the two rear wheels, thus keeping the vehicle in a controllable sideslip state.

[0018] During the process of controlling the right rear motor to drive the right rear wheel at a higher speed than the left rear motor to drive the left rear wheel, before the steering wheel is turned to the right at an angle greater than zero, the left front motor to drive the left front wheel is controlled to increase its speed while the right front motor to drive the right front wheel is controlled to decrease its speed. That is, in the electric vehicle's drifting state, before the driver counter-steering, and after reaching the drift equilibrium point, the electric vehicle controls the left front motor to increase its speed and the right front motor to decrease its speed, thereby generating a force to correct the electric vehicle's direction and promptly correct it, thus allowing the electric vehicle to enter a stable drift state. Taking a leftward circular drift as an example, during the electric vehicle's acceleration phase, the left and right front wheels maintain synchronous speeds matching the vehicle speed. When the steering wheel is quickly turned to the left, the left and right front wheels generate a differential speed corresponding to the turning radius due to Ackerman geometry constraints. As the rear tires exceed the road surface adhesion limit, the left and right front wheels still maintain a rolling speed consistent with the steering path to provide lateral guiding force. When the rear of the car swings to the right due to oversteer, before the driver can counter-steer, the system actively increases the speed of the left front motor driving the left front wheel and decreases the speed of the right front motor driving the right front wheel to correct the drift. Once the car enters a stable drift phase, the left and right front wheels maintain a differential rolling motion that matches the turning radius, following a circular motion.

[0019] According to the solution in this application, when an electric vehicle is drifting, the speed of the left and right motors on the front axle is adjusted by a distributed drive system to assist the driver in counter-drifting, thereby reducing the skill requirements of the driver for drifting operations and improving the driving experience and safety of the vehicle.

[0020] In conjunction with the first aspect, in some implementations of the first aspect, the control method specifically includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, when the accelerator pedal opening is reduced to a second preset opening, controlling the speed of both the right rear motor and the left rear motor to decrease, and controlling the difference between the speeds of the right rear motor and the left rear motor to decrease.

[0021] When the accelerator pedal opening decreases to the second preset opening, it indicates that the driver has released the accelerator pedal, at which point the driver may wish to exit the drift state. The distributed drive system responds to the driver's accelerator pedal operation by dynamically adjusting the speed of the rear axle motors. When the driver reduces the accelerator pedal opening to the second preset opening, the distributed drive system reduces the speed of the right and left rear motors and decreases the speed difference between them. Reducing the speed and speed difference of the two rear wheels during drifting allows the two rear wheels to regain traction, recovering from a high-slip state to a rotating state, helping the electric vehicle transition or exit the drift state more smoothly, and avoiding the risk of loss of control due to excessive speed differences.

[0022] According to the solution of this application, when the driver actively releases the accelerator pedal in order to exit the drift, the accelerator pedal opening is reduced to a second preset opening, which actively reduces the speed and speed difference of the two rear wheels, improves the stability and controllability of the electric vehicle when exiting the drift, decelerates and exits the drift state more smoothly, reduces the probability of loss of control due to driver misoperation, reduces the skill requirements of the driver for drift operation, and improves the driving experience and safety of the vehicle.

[0023] In conjunction with the first aspect, in some implementations of the first aspect, the control method further includes, during the process of controlling the rotational speed of the right rear motor driving the right rear wheel to be greater than the rotational speed of the left rear motor driving the left rear wheel, when the opening degree of the accelerator pedal is greater than a third preset opening degree but less than a first preset opening degree for a first preset duration, actively controlling the rotational speeds of both the right rear motor and the left rear motor to increase. Wherein, the third preset opening degree is less than the first preset opening degree but greater than the second preset opening degree.

[0024] When the accelerator pedal opening is greater than the third preset opening but less than the first preset opening, it indicates that the driver may have accidentally released the accelerator pedal by a small amount, but the driver did not actually intend to exit the drift. The distributed drive system dynamically adjusts the speed of the rear axle motors in response to the driver's accelerator pedal operation. Due to the decrease in accelerator pedal opening, the speed of the two rear axle motors decreases, which may cause the electric vehicle to exit the drift state. When the accelerator pedal opening is greater than the third preset opening but less than the first preset opening for a first preset duration, the distributed drive system actively controls the speed of both the right and left rear motors to increase. By increasing the speed of the two rear wheels, the electric vehicle can improve the rear wheel slip state or enhance the drift tendency, helping the electric vehicle to maintain or strengthen the drift state more smoothly and avoiding the risk of drift interruption due to insufficient speed.

[0025] It should be understood that the third preset opening is pre-calibrated based on actual vehicle experiments and / or model calculations, or it can be pre-set by comprehensively considering the needs of the whole vehicle and vehicle performance.

[0026] According to the solution of this application, when the driver accidentally releases the accelerator pedal with a small opening, the accelerator pedal opening is greater than a third preset opening and less than a first preset opening for a first preset duration, which actively increases the rotational speed of the two rear wheels, improves the drift stability and controllability of the electric vehicle, maintains the drift state, reduces the probability of drift interruption caused by driver misoperation, reduces the skill requirements of the driver for drift operation, and improves the driving experience and safety of the vehicle.

[0027] In conjunction with the first aspect, in some implementations of the first aspect, the control method further includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, when the steering wheel turns to the right at an angle greater than a second preset angle, controlling the difference in speed between the right rear motor and the left rear motor to decrease.

[0028] When the steering wheel is turned to the right at an angle greater than the second preset angle, it indicates that the driver may wish to adjust the vehicle's steering tendency to maintain control or exit a drift. The distributed drive system responds to the driver's steering wheel input by dynamically adjusting the speed of the rear axle motors. When the steering wheel is turned to the right at an angle greater than the second preset angle, the distributed drive system actively controls to reduce the speed difference between the right and left rear motors. By reducing the speed difference between the two rear wheels, the electric vehicle can adjust its steering tendency, helping it exit a drift more smoothly and avoiding the risk of loss of control due to excessive speed differences.

[0029] According to the solution in this application, when the driver turns the steering wheel to the right at an angle greater than the second preset angle during drifting, the speed difference between the two rear wheels is actively reduced, thereby improving the stability and controllability of the electric vehicle, safely exiting the drift state, reducing the probability of loss of control due to improper driver operation, reducing the skill requirements of the driver for drifting operations, and improving the driving experience and safety of the vehicle. In conjunction with the first aspect, in some implementations of the first aspect, the control method further includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, when the angle of the steering wheel turning to the right continues to increase and is less than the second preset angle for a second preset duration, controlling the speed of the left front motor driving the left front wheel to decrease and controlling the speed of the right front motor driving the right front wheel to increase.

[0030] When the steering wheel is turned to the right at an angle that continuously increases but is less than a second preset angle for a second preset duration, it indicates that the driver may be attempting to correct the vehicle's drift by counter-steering. However, the counter-steering angle is insufficient, requiring assistance from the electric vehicle to maintain control. The distributed drive system responds to the driver's steering wheel inputs and dynamically adjusts the speed of the front axle motor. When the steering wheel is turned to the right at an angle that continuously increases but is less than a second preset angle for a second preset duration, the distributed drive system actively controls the left front motor to reduce the speed of the left front wheel and the right front motor to increase the speed of the right front wheel. By reducing the speed of the left front wheel and increasing the speed of the right front wheel, the electric vehicle can adjust the steering tendency of the front wheels, helping the vehicle maintain its drift more smoothly and preventing it from exiting the drift state due to insufficient counter-steering.

[0031] According to the solution of this application, when the driver counter-steers to correct the drift state, the angle of the steering wheel turning to the right continuously increases and remains less than the second preset angle for the second preset duration, actively adjusting the speed difference of the front axle motor, improving the drift stability and controllability of the electric vehicle, helping the driver to better complete the counter-steering operation, reducing the probability of loss of control due to improper steering wheel operation, reducing the skill requirements of the driver for drift operation, and improving the driving experience and safety of the vehicle.

[0032] In conjunction with the first aspect, in some implementations of the first aspect, the rotational speed of the right rear motor driving the right rear wheel is controlled to be greater than the rotational speed of the left rear motor driving the left rear wheel. Specifically, this includes controlling the increase rate of the right rear motor to be greater than the increase rate of the left rear motor during the process of turning the steering wheel to the left.

[0033] When the steering wheel is turned to the left, the driver wants the vehicle to enter a drift state to initiate a drift. This requires both rear wheels to break traction, so the speeds of both the right and left rear motors increase. Simultaneously, to control the speed at which the right rear motor drives the right rear wheel to be greater than the speed at which the left rear motor drives the left rear wheel, the distributed drive system controls the right rear motor to increase its speed at a greater rate than the left rear motor when the steering wheel is turned to the left. By increasing the speed of the right rear motor more quickly, while the left rear motor increases its speed more slowly, the speed difference between the rear wheels of the electric vehicle can reach the conditions required for a drift more rapidly, thus helping the vehicle enter a drift state and initiate a drift more quickly.

[0034] According to the solution in this application, when the driver turns the steering wheel to the left to initiate a drift, during the process of turning the steering wheel to the left, the increase rate of the right rear motor is actively controlled to be greater than that of the left rear motor, thereby improving the tail-swing response speed and drift initiation agility of the electric vehicle, reducing the skill requirements of the driver for drifting operations, and improving the driving experience and safety of the vehicle.

[0035] In conjunction with the first aspect, in some implementations of the first aspect, the control method also includes reducing the speed of both the right rear motor and the left rear motor during the process of the steering wheel returning to center to the right.

[0036] As the steering wheel is turned to the right to return to center, it indicates that the driver may wish to exit the drift state or resume normal driving. The distributed drive system responds to the driver's steering wheel input and dynamically adjusts the speed of the rear axle motors. During the steering wheel return to center, the distributed drive system actively reduces the speeds of both the right and left rear motors. By reducing the speeds of the two rear wheels, the electric vehicle can gradually return to normal driving, avoiding instability caused by excessively high speeds after the drift ends.

[0037] According to the solution in this application, when the driver straightens the steering wheel to the right to exit the drift, the rotational speed of the two rear wheels is actively reduced during the process of straightening the steering wheel to the right, thereby reducing the driving force of the rear wheels and helping the electric vehicle to smoothly transition to normal driving state. This improves the stability and controllability of the vehicle, reduces the skill requirements of the driver for drifting operations, and enhances the driving experience and safety of the vehicle.

[0038] In conjunction with the first aspect, in some implementations of the first aspect, controlling the speed at which the right rear motor drives the right rear wheel is less than the speed at which the left rear motor drives the left rear wheel specifically includes controlling the speed of the right rear motor to decrease and controlling the speed of the left rear motor to increase.

[0039] When the driver desires the vehicle to enter or maintain a drift state, the distributed drive system responds to the driver's request by adjusting the speed of the rear axle motors. Specifically, the speed at which the right rear motor drives the right rear wheel is controlled to be lower than the speed at which the left rear motor drives the left rear wheel. This includes controlling the speed of the right rear motor to decrease and the speed of the left rear motor to increase. During the drift stabilization phase, in order to maintain the electric vehicle's drift and prevent loss of control, the speed difference between the two rear wheel motors is adjusted, thereby allowing the electric vehicle to maintain yaw rate and sideslip.

[0040] According to the solution in this application, the speed difference of the rear wheels of the electric vehicle is precisely controlled, thereby helping the electric vehicle to enter or maintain a drift state more smoothly, reducing the skill requirements of the driver for drifting operations, improving the stability and safety of the electric vehicle, and enhancing the overall driving experience.

[0041] In conjunction with the first aspect, in some implementations of the first aspect, the control method specifically includes controlling the rate of decrease of the speed of the right rear motor to be less than the rate of increase of the speed of the left rear motor.

[0042] The distributed drive system controls the speed reduction rate of the right rear motor to be different from the speed increase rate of the left rear motor. The speed reduction rate of the right rear motor is less than the speed increase rate of the left rear motor, which allows the electric vehicle to adjust its orientation more quickly while maintaining rear wheel slippage, thus entering a drift state more quickly.

[0043] According to the solution in this application, the speed difference of the rear wheels of the electric vehicle is precisely controlled, thereby helping the electric vehicle to enter or maintain a drift state more smoothly, reducing the skill requirements of the driver for drifting operations, improving the stability and safety of the electric vehicle, and enhancing the overall driving experience.

[0044] In conjunction with the first aspect, in some implementations of the first aspect, the control method specifically includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, before the steering wheel turns to the right at an angle greater than zero, when the yaw rate of the electric vehicle increases to a preset angular velocity, controlling the speed of the left front motor driving the left front wheel to increase and controlling the speed of the right front motor driving the right front wheel to decrease.

[0045] During drifting, the electric vehicle's speed, yaw rate, and sideslip angle are monitored in real time to determine its attitude. The vehicle speed allows for the calculation of elliptical safety boundaries for both yaw rate and sideslip angle. These safety boundaries are obtained in real-time during drifting. When the yaw rate increases to a preset value, the vehicle enters its drift equilibrium point. Correction is then initiated by increasing the rotational speed of the left front motor driving the left front wheel and decreasing the rotational speed of the right front motor driving the right front wheel.

[0046] According to the solution of this application, when the yaw rate of the electric vehicle increases to a preset yaw rate, before the steering wheel turns to the right at an angle greater than zero, the speed difference of the front axle motor is actively adjusted according to the yaw rate to improve the drift stability and controllability of the electric vehicle, help the vehicle enter the drift state more smoothly, reduce the probability of loss of control due to improper operation by the driver, reduce the skill requirements of the driver for drifting operations, and improve the driving experience and safety of the vehicle.

[0047] In conjunction with the first aspect, in some implementations of the first aspect, controlling the left front motor to increase the speed of the left front wheel and controlling the right front motor to decrease the speed of the right front wheel, specifically includes controlling the left front motor to increase the speed of the left front wheel and controlling the right front motor to decrease the speed of the right front wheel so that the steering wheel generates a force to turn to the right.

[0048] Once the drift equilibrium point is reached, the left front motor speed increases while the right front motor speed decreases, generating hand force on the steering wheel to assist the driver in timely counter-steering. The distributed drive system adjusts the speed difference between the two front axle motors, thereby generating hand force on the steering wheel, with the electric vehicle indicating the timing and angle of counter-steering.

[0049] According to the solution in this application, after entering the drift equilibrium point, the speed difference of the front axle motor is adjusted through the distributed drive system to actively generate a rightward turning force on the steering wheel, which helps the driver to counter-steer in time, reduces the skill requirements of the driver for drifting operations, and improves the driving experience and safety of the vehicle.

[0050] In conjunction with the first aspect, in some implementations of the first aspect, the control method further includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, when the angle of the steering wheel turning to the right is less than a third preset angle, controlling the speed of both the right rear motor and the left rear motor to decrease and controlling the difference between the speeds of the right rear motor and the left rear motor to decrease.

[0051] In conjunction with the first aspect, in some implementations of the first aspect, the electric vehicle is used to control the electric vehicle to enter drift mode by touching the central control screen of the electric vehicle or activating the drift button.

[0052] It should be understood that when an electric vehicle is drifting, it is in drift mode, which is activated by the driver. The electric vehicle will only enter assisted drift control when it is in drift mode and the conditions are met: the accelerator pedal opening is increased to a value greater than a first preset opening, and the steering wheel angle to one side is greater than a first preset angle. Therefore, being in drift mode does not mean that drift control is already in progress, but being in drift control means that the electric vehicle must be in drift mode.

[0053] In one possible embodiment, the electric vehicle includes a drift button. When the drift button is off, the electric vehicle does not perform assisted drift control, and the drive system outputs the torque indicated by the opening of the electric vehicle's accelerator pedal. When the drift button is on, the electric vehicle enters drift mode, detects the opening of the accelerator pedal and the steering wheel angle, and when the conditions are not met, controls the drive system to output the torque indicated by the opening of the electric vehicle's accelerator pedal.

[0054] Electric vehicles are equipped with a drift button for driver operation. For example, the drift button can be a physical button; the driver presses this physical button to activate the electric vehicle's drift mode, thereby initiating drift control when certain conditions are met. Alternatively, the drift button can be a virtual button on the central control screen, which the driver can select to activate the drift mode. Furthermore, the drift button can also be indirectly configured, for example, integrated into a sport mode button or other function buttons. This application does not limit the method or form of the drift button's configuration.

[0055] According to the proposed solution, by setting a drift mode that the driver can freely choose whether to activate, the controllability and safety of the vehicle are improved, and the driving experience and enjoyment are enhanced.

[0056] Secondly, this application provides a vehicle controller for electric vehicles, which is used to implement the control methods described in the first aspect and its various implementations above.

[0057] Thirdly, this application provides an electric vehicle, which includes a distributed drive system, an accelerator pedal, and a steering wheel. The distributed drive system is used to implement the control method described in the first aspect and its various implementations above. The accelerator pedal is used to instruct the distributed drive system to output torque to the four wheels of the electric vehicle, and the steering wheel is used to instruct the steering angle of the wheels of the electric vehicle.

[0058] Other beneficial effects can be found in the description of the first aspect, and will not be repeated here. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the vehicle tire friction limit circle provided in an embodiment of this application; Figure 2 This is a schematic diagram of an electric vehicle provided in an embodiment of this application; Figure 3 This is a schematic diagram of the electric vehicle architecture provided in an embodiment of this application; Figure 4 This is a schematic diagram of the drift button for an electric vehicle provided in an embodiment of this application; Figure 5 This is a schematic diagram of electric vehicle drifting provided in an embodiment of this application; Figure 6 This is a schematic diagram of an electric vehicle drift control provided in an embodiment of this application; Figure 7 This is another schematic diagram of electric vehicle drift control provided in the embodiments of this application; Figure 8 This is a schematic diagram of the electric vehicle assisted drift control architecture provided in the embodiments of this application; Figure 9 This is a schematic diagram of the electric vehicle assisted drift control process provided in the embodiments of this application. Detailed Implementation

[0060] The technical solutions in this application will now be described in conjunction with the accompanying drawings. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments.

[0061] Drifting is a sport that focuses on specific driving techniques. Vehicle drifting involves using oversteer to steer the vehicle sideways through a corner. Drifting occurs through the interaction between the tires and the road surface, generating lateral and longitudinal forces on the tires. When the rear-wheel drive lateral force exceeds the road surface traction, the tires generate lateral velocity, causing sideslip, and the wheels travel along the tangent of the vehicle's circumference, resulting in a drift. Drivers can drift by manipulating the drivetrain, brakes, and steering wheel to achieve small-radius turns, satisfying the needs of racing, driving pleasure, and maneuvering in tight areas. However, drifting by a driver requires highly skilled driving techniques, which is difficult for ordinary drivers to achieve. The principle behind drifting is to cause the rear wheels to lose most or all of their traction, while the front wheels maintain traction. At this point, as long as the front wheels have a certain lateral force, the vehicle will fishtail, resulting in a drift.

[0062] Here's an example of drifting via a driving mechanism: First, in the initial stage, the electric vehicle travels straight before drifting and then brakes. Figure 1 As shown at point A on the circle representing the limit of friction, shifting the vehicle's center of gravity reduces the axle load on the rear axle, which is beneficial for the rear axle to break through road adhesion. Then comes the sideslip drift phase, during which the driver can adjust the steering wheel, such as... Figure 1 Point B, representing the friction limit circle, generates a sideslip angle and lateral force. Constrained by the friction limit circle, the increased driving force causes the lateral force to decrease, exceeding the rear wheel friction limit circle, generating lateral velocity, and causing sideslip. The driver then counter-steers to correct the vehicle's attitude, causing the wheels to travel along the tangent of the vehicle's circumference. Finally, in the recovery phase, the driver releases the throttle, reducing driving torque and gradually straightens the steering wheel to reduce lateral force, thus exiting the drift state.

[0063] It should be understood that drifting through driver control requires the driver to have a high level of driving skills, which is difficult for ordinary drivers to achieve.

[0064] To address the aforementioned issues, this application provides a control method for electric vehicles, comprising a vehicle controller and an electric vehicle. When the electric vehicle is drifting, a distributed drive system is used to actively adjust the rotational speed of the two rear wheels, enabling the electric vehicle to quickly enter a tail-swing state and maintain the drifting trend. This reduces the skill requirements of the driver for drifting operations, lowers the risk of drift loss of control, and improves the driving experience and safety of the vehicle.

[0065] Figure 2 and Figure 3 This is a schematic diagram of the architecture of the electric vehicle 10 provided in the embodiments of this application.

[0066] like Figure 1 As shown, the electric vehicle 10 includes a vehicle controller 20 and a drive system 50. The drive system 50 includes a motor controller 40 and a drive motor 30. 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 the electric vehicle 10.

[0067] In one embodiment, the electric vehicle 10 has a distributed four-motor drive architecture, with the drive motors positioned beside the driving wheels and controlled by individual motor controllers 40. In another embodiment, the drive motors for driving the two front wheels or the two rear wheels are arranged together. There may be one or more motor controllers 40. Each motor controller 40 may correspond one-to-one with a drive motor, or one motor controller 40 may correspond to multiple drive motors. The motor controllers 40 control the output torque of one or more drive motors to drive the electric vehicle 10.

[0068] In one embodiment, such as Figure 3 As shown in (a), the electric vehicle 10 has a distributed four-motor drive architecture, with the drive motors positioned beside the driving wheels and controlled by individual motor controllers. The electric vehicle 10 is also as follows... Figure 3 The four-drive motor drive architecture shown in (b) is a system in which two drive motors for driving two front wheels or two rear wheels are set together.

[0069] For example, the electric vehicle 10 includes four motor controllers: motor controller 41, motor controller 42, motor controller 43, and motor controller 44. The four motors include drive motor 31, drive motor 32, drive motor 33, and drive motor 34. Motor controller 41 controls drive motor 31 to drive wheel 51, motor controller 42 controls drive motor 32 to drive wheel 52, motor controller 43 controls drive motor 33 to drive wheel 53, and motor controller 44 controls drive motor 34 to drive wheel 54.

[0070] In this application, for the sake of brevity, the drive motor 30 used to drive the right front wheel is referred to as the right front motor, the drive motor 30 used to drive the left front wheel is referred to as the left front motor, the drive motor 30 used to drive the right rear wheel is referred to as the right rear motor, and the drive motor 30 used to drive the left rear wheel is referred to as the left rear motor.

[0071] The electric vehicle 10 also includes an accelerator pedal and a steering wheel. The accelerator pedal is used to instruct the drive system 50 to output drive torque to the wheels of the electric vehicle 10. The steering wheel angle is used to instruct the steering angle of the two front wheels.

[0072] The accelerator pedal in this application is also called the power pedal or throttle pedal. The opening degree of the accelerator pedal indicates the amount of driving force required by the driver. The larger the opening degree of the accelerator pedal, the greater the driver's demand for driving force, and the greater the torque required from the drive motor. The drive system controls the amount of current output to the drive motor according to the opening degree of the accelerator pedal, so that the drive motor outputs the torque indicated by the throttle pedal opening degree. The larger the opening degree of the accelerator pedal, the greater the current, and thus the greater the torque output by the drive motor. The smaller the opening degree of the accelerator pedal, the smaller the current, and thus the smaller the torque output by the drive motor. The driving torque output by the drive system varies with the opening degree of the accelerator pedal.

[0073] In one embodiment, each motor controller 40 is directly connected to the accelerator pedal and controls the output torque of the corresponding drive motor according to the torque signal output by the accelerator pedal.

[0074] In one embodiment, each motor controller 40 is connected to a resolver sensor. The resolver sensor is used to detect the rotational speed of the drive motor 30 controlled by the motor controller 40, and the motor controller 40 is used to receive signals from the resolver sensor. The resolver sensor can accurately detect the position, direction, and speed of the motor rotor, and is responsible for monitoring and extracting the rotational speed of the drive motor. It has a high sampling rate and is directly connected to the motor controller 40, resulting in short signal transmission time and higher stability.

[0075] In one embodiment, the motor controller 40 also obtains the vehicle speed, yaw rate and center of gravity sideslip angle of the electric vehicle 10 from the vehicle controller 20 or other sensors of the electric vehicle 10 through a signal interface.

[0076] It should be understood that the vehicle controller provided in this application is a motor controller 40, a vehicle controller 20, or other controllers with control capabilities.

[0077] like Figure 4 As shown, in one embodiment, the electric vehicle 10 is used to control the electric vehicle 10 to enter drift mode by touching the central control screen of the electric vehicle 10 or activating the drift button.

[0078] It should be understood that the electric vehicle 10 is in drift mode when drifting, and this drift mode is activated by the driver. The electric vehicle 10 will only enter assisted drift control when it is in drift mode and all drift conditions are met. The fact that the electric vehicle 10 is in drift mode does not mean that drift control is already in progress, but being in drift control means that the electric vehicle 10 must be in drift mode.

[0079] The electric vehicle 10 is equipped with a drift button for driver operation. Exemplarily, the drift button can be a physical button; the driver presses this physical button to activate the drift mode of the electric vehicle 10, thereby initiating drift control when certain conditions are met. Alternatively, the drift button can be a virtual button on the central control screen, allowing the driver to activate the drift mode of the electric vehicle 10 by selecting that mode. Furthermore, the drift button can also be indirectly configured, for example, integrated into a sport mode button or other function buttons. This application does not limit the method or form of the drift button's configuration.

[0080] Figures 5-7 This is a schematic diagram illustrating the drifting process of the electric vehicle 10 provided in an embodiment of this application. The following is in conjunction with… Figures 5 to 7 The control method for electric vehicle 10, vehicle controller and electric vehicle 10 provided in this application are described.

[0081] During the operation of the electric vehicle 10, the control method is used to assist the electric vehicle 10 in drifting by controlling the distributed drive system and steering system of the electric vehicle 10 after the drift mode of the electric vehicle 10 is activated.

[0082] The control method includes controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel after the accelerator pedal opening of the electric vehicle 10 is greater than a first preset opening and the steering wheel is turned to the left by an angle greater than a first preset angle, but before the steering wheel is turned to the right by an angle greater than zero. When the steering wheel is turned to the right by an angle greater than zero and less than a second preset angle, controlling the speed of the right rear motor driving the right rear wheel to be less than the speed of the left rear motor driving the left rear wheel.

[0083] like Figure 6As shown, when the drift mode of the electric vehicle 10 is activated, the driver depresses the accelerator pedal and simultaneously turns the steering wheel sharply. After the accelerator pedal opening of the electric vehicle 10 exceeds a first preset opening and the steering wheel is turned to the left at an angle greater than a first preset angle, the electric vehicle 10 determines the driver's intention to drift based on the accelerator pedal opening and steering wheel rotation angle. Therefore, it controls the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel. Specifically, the right rear motor drives the right rear wheel, and the left rear motor drives the left rear wheel. The driver's desired torque is identified by the accelerator pedal opening and converted into an increment in motor speed. Upon recognizing the driver's drift intention, the rear axle motor speed is corrected to enter the drift state. By actively controlling the speed of the right rear wheel to be greater than that of the left rear wheel, the two rear wheels of the electric vehicle 10 break through the road surface adhesion and begin to slip. The front wheel of the electric vehicle 10 turns to one side, and the electric vehicle 10 generates a side slip angle and lateral force. The speed difference between the two rear wheels causes the electric vehicle 10 to generate a leftward yaw rate, and the electric vehicle 10 quickly enters a tail-swing state.

[0084] In a drift state, the rear of electric vehicle 10 swings outward. Without correction, electric vehicle 10 will continue to spin or even turn around. Once electric vehicle 10 reaches the drift equilibrium point, correction is required. The driver counter-steers in the opposite direction of the drift, causing the front wheels to point in the actual driving direction. This balances the rotational torque generated by the sideslip of the two rear wheels, maintaining a controllable sideslip. When the steering wheel is turned to the right at an angle greater than zero and less than a second preset angle (i.e., in a drift state with the steering wheel counter-steered), the speed at which the right rear motor drives the right rear wheel is lower than the speed at which the left rear motor drives the left rear wheel. During the drift stabilization phase, to maintain the drift and prevent loss of control, the speed difference between the two rear wheel motors is adjusted, thus maintaining the yaw rate and sideslip state of electric vehicle 10.

[0085] It should be understood that the first preset opening, the first preset angle, and the second preset angle are pre-calibrated based on actual vehicle experiments and / or model calculations, or they can be pre-set by comprehensively considering the needs of the whole vehicle and the vehicle performance.

[0086] It should be understood that this application uses drifting with the steering wheel turned to the left as an example for illustration. When drifting with the steering wheel turned to the right, the control method can be modified accordingly. For example, after the accelerator pedal opening of the electric vehicle 10 is greater than a first preset opening and the angle of the steering wheel turning to the right is greater than a first preset angle, but before the angle of the steering wheel turning to the left is greater than zero, the speed at which the left rear motor drives the left rear wheel is controlled to be greater than the speed at which the right rear motor drives the right rear wheel. When the angle of the steering wheel turning to the left is greater than zero and less than a second preset angle, the speed at which the left rear motor drives the left rear wheel is controlled to be less than the speed at which the right rear motor drives the right rear wheel. The same modifications can be made for drifting with the steering wheel turned to the right, and will not be elaborated further below.

[0087] According to the solution of this application, when the electric vehicle 10 is drifting, the driver's drifting intention is identified by the accelerator pedal and steering wheel and the vehicle is controlled to enter the drift state. The torque expected by the driver is converted into an increment of the motor speed, and the target speed of the rear axle motor is corrected, making it easier for the electric vehicle 10 to drift. This reduces the probability of the vehicle losing control or exiting the drift due to driver misoperation, enabling the vehicle to drift stably. It also reduces the skill requirements of the driver for drifting operations and improves the driving experience and safety of the vehicle.

[0088] In one possible embodiment, the rotational speed of the right rear motor driving the right rear wheel is controlled to be greater than the rotational speed of the left rear motor driving the left rear wheel. Specifically, this includes controlling the increase rate of the right rear motor to be greater than the increase rate of the left rear motor during the process of turning the steering wheel to the left.

[0089] When the steering wheel is turned to the left, the driver wants the vehicle to enter a drift state to initiate a drift. This requires both rear wheels to break traction, so the speeds of both the right and left rear motors increase. Simultaneously, to control the speed at which the right rear motor drives the right rear wheel to be greater than the speed at which the left rear motor drives the left rear wheel, the distributed drive system controls the rate of increase of the right rear motor to be greater than that of the left rear motor when the steering wheel is turned to the left. By increasing the speed of the right rear motor more quickly, while the speed of the left rear motor increases more slowly, the speed difference between the rear wheels of the electric vehicle 10 can reach the conditions required for a drift more quickly, thus helping the vehicle enter a drift state and initiate a drift more rapidly.

[0090] In one possible embodiment, controlling the right rear motor to drive the right rear wheel at a speed lower than the left rear motor to drive the left rear wheel specifically includes controlling the speed of the right rear motor to decrease and controlling the speed of the left rear motor to increase.

[0091] When the driver desires the vehicle to enter or maintain a drift state, the distributed drive system responds to the driver's request by adjusting the speed of the rear axle motors. Specifically, the speed at which the right rear motor drives the right rear wheel is controlled to be lower than the speed at which the left rear motor drives the left rear wheel. This includes controlling the speed of the right rear motor to decrease and the speed of the left rear motor to increase. During the drift stabilization phase, in order to maintain the drift of the electric vehicle 10 and prevent loss of control, the speed difference between the two rear wheel motors is adjusted, thereby allowing the electric vehicle 10 to maintain yaw rate and sideslip.

[0092] In one possible embodiment, the control method specifically includes controlling the rate of decrease of the right rear motor's rotational speed to be less than the rate of increase of the left rear motor's rotational speed.

[0093] The distributed drive system controls the speed reduction rate of the right rear motor and the speed increase rate of the left rear motor to be different. The speed reduction rate of the right rear motor is less than the speed increase rate of the left rear motor, which allows the electric vehicle 10 to adjust its body orientation more quickly while maintaining the rear wheel slippage, thus entering the drift state more quickly.

[0094] In one possible embodiment, the control method further includes, during the process of controlling the rotational speed of the right rear motor driving the right rear wheel to be greater than the rotational speed of the left rear motor driving the left rear wheel, when the accelerator pedal opening is greater than a third preset opening and less than a first preset opening for a first preset duration, actively controlling the rotational speeds of both the right and left rear motors to increase. The third preset opening is less than the first preset opening and greater than a second preset opening.

[0095] When the accelerator pedal opening is greater than the third preset opening but less than the first preset opening, it indicates that the driver may have accidentally released the accelerator pedal by a small amount, but the driver did not actually intend to exit the drift. The distributed drive system dynamically adjusts the speed of the rear axle motors in response to the driver's operation of the accelerator pedal. Due to the decrease in the accelerator pedal opening, the speed of the two rear axle motors decreases, which may cause the electric vehicle 10 to exit the drift state. When the accelerator pedal opening is greater than the third preset opening but less than the first preset opening for a first preset duration, the distributed drive system actively controls the speed of both the right and left rear motors to increase. By increasing the speed of the two rear wheels, the electric vehicle 10 can improve the rear wheel slip state or enhance the drift tendency, helping the electric vehicle 10 to maintain or strengthen the drift state more smoothly and avoiding the risk of drift interruption due to insufficient speed.

[0096] It should be understood that the third preset opening is pre-calibrated based on actual vehicle experiments and / or model calculations, or it can be pre-set by comprehensively considering the needs of the whole vehicle and vehicle performance.

[0097] In one possible embodiment, the control method further includes reducing the speed of both the right rear motor and the left rear motor during the process of the steering wheel returning to center to the right.

[0098] As the steering wheel is turned to the right to return to center, it indicates that the driver may wish to exit the drift state or resume normal driving. The distributed drive system responds to the driver's steering wheel input and dynamically adjusts the speed of the rear axle motors. During the steering wheel return to center, the distributed drive system actively reduces the speeds of both the right and left rear motors. By reducing the speeds of the two rear wheels, the electric vehicle 10 can gradually return to normal driving, avoiding instability caused by excessively high speeds after the drift ends.

[0099] In one possible embodiment, the control method specifically includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, when the accelerator pedal opening is reduced to a second preset opening, controlling the speed of both the right rear motor and the left rear motor to decrease, and controlling the difference between the speeds of the right rear motor and the left rear motor to decrease.

[0100] When the accelerator pedal opening decreases to the second preset opening, it indicates that the driver has released the accelerator pedal, and at this point, the driver may wish to exit the drift state. The distributed drive system responds to the driver's accelerator pedal operation by dynamically adjusting the speed of the rear axle motors. When the driver reduces the accelerator pedal opening to the second preset opening, the distributed drive system reduces the speed of the right and left rear motors and decreases the speed difference between them. Reducing the speed and speed difference of the two rear wheels during drifting allows the two rear wheels to regain traction, recovering from a high slip state to a rotating state, helping the electric vehicle 10 to transition or exit the drift state more smoothly and avoiding the risk of loss of control due to excessive speed differences.

[0101] In one possible embodiment, the control method further includes, during the process of controlling the right rear motor to drive the right rear wheel at a speed greater than the left rear motor to drive the left rear wheel, when the steering wheel is turned to the right at an angle greater than a second preset angle, controlling the difference in speed between the right rear motor and the left rear motor to decrease.

[0102] When the steering wheel is turned to the right at an angle greater than the second preset angle, it indicates that the driver may wish to adjust the vehicle's steering tendency to maintain control or exit the drift. The distributed drive system responds to the driver's steering wheel input and dynamically adjusts the speed of the rear axle motors. When the steering wheel is turned to the right at an angle greater than the second preset angle, the distributed drive system actively controls to reduce the speed difference between the right and left rear motors. By reducing the speed difference between the two rear wheels, the electric vehicle 10 can adjust its steering tendency, helping it exit the drift state more smoothly and avoiding the risk of loss of control due to excessive speed differences.

[0103] For example, such as Figure 5 and Figure 6As shown, at time t1, the driver depresses the accelerator pedal, and the accelerator pedal opening of the electric vehicle 10 begins to increase. The speeds of the left and right rear motors increase accordingly. Subsequently, the driver turns the steering wheel to the left. At time t2, the accelerator pedal opening of the electric vehicle 10 is greater than a first preset opening, and the angle of the steering wheel turning to the left is greater than a first preset angle. This controls the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel. During the leftward steering wheel turn, the rate of increase of the right rear motor is controlled to be greater than the rate of increase of the left rear motor, thereby controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel. The speed difference between the two rear wheels causes the electric vehicle 10 to generate a leftward yaw rate, and the electric vehicle 10 quickly enters a drift state. At time t3, electric vehicle 10 enters the drift equilibrium point. The driver counter-steers to correct the excessive fishtailing, controlling the speed of the right rear motor to decrease and the speed of the left rear motor to increase. This ensures that the speed at which the right rear motor drives the right rear wheel is less than the speed at which the left rear motor drives the left rear wheel. After time t3, electric vehicle 10 enters a stable drift state. At time t4, the driver may have accidentally released the accelerator pedal by a small amount. The accelerator pedal opening is greater than the third preset opening but less than the first preset opening. The speeds of the right and left rear motors decrease as the accelerator pedal opening decreases. From time t4 to time t5, the accelerator pedal opening remains greater than the third preset opening but less than the first preset opening for a first preset duration. The speeds of both the right and left rear motors are actively increased. By increasing the speeds of the two rear wheels, electric vehicle 10 can improve rear wheel slip or enhance drift tendency, helping it maintain or strengthen the drift state more smoothly and avoiding the risk of drift interruption due to insufficient speed. At time t6, the steering wheel is straightened or the accelerator pedal is released, the accelerator pedal opening is reduced to the second preset opening, the speed of both the right and left rear motors is reduced, and the difference between the speeds of the right and left rear motors is reduced. The steering wheel is turned to the right at an angle greater than the second preset angle, and the difference between the speeds of the right and left rear motors is reduced.

[0104] In one possible embodiment, the control method further includes, while controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, before the steering wheel turns to the right at an angle greater than zero, controlling the speed of the left front motor driving the left front wheel to increase and controlling the speed of the right front motor driving the right front wheel to decrease.

[0105] Existing drift-assisted technologies typically put the vehicle in a pure rear-wheel-drive state, and the counter-drift still relies on the driver to operate the steering wheel, which is quite difficult to operate. Novice drivers cannot accurately grasp the timing and speed of the counter-steering, which can easily lead to loss of control or inability to maintain the drift.

[0106] Once the electric vehicle 10 enters the drift equilibrium point, it needs to counter-steer in time to correct the direction, so that the front wheels point in the actual driving direction, balance the rotational torque generated by the sideslip of the two rear wheels, and thus keep the vehicle in a controllable sideslip state.

[0107] During the process of controlling the right rear motor to drive the right rear wheel at a higher speed than the left rear motor to drive the left rear wheel, before the steering wheel is turned to the right at an angle greater than zero, the left front motor to drive the left front wheel is controlled to increase its speed while the right front motor to drive the right front wheel is controlled to decrease its speed. That is, in the drift state of electric vehicle 10, before the driver counter-steering, after reaching the drift equilibrium point, electric vehicle 10 controls the left front motor to increase its speed and the right front motor to decrease its speed, thereby generating a force to correct the direction of electric vehicle 10, making timely corrections, and thus allowing electric vehicle 10 to enter a stable drift state. Taking the process of drifting to the left in a circle as an example, during the acceleration phase of electric vehicle 10, the left and right front wheels maintain synchronous speeds matching the vehicle speed. When the steering wheel is quickly turned to the left, the left and right front wheels generate differential speeds corresponding to the turning radius due to Ackerman geometry constraints. As the rear tires exceed the road adhesion limit, the left and right front wheels still maintain a rolling speed consistent with the steering path to provide lateral guiding force. When the rear of the car swings to the right due to oversteer, before the driver can counter-steer, the system actively increases the speed of the left front motor driving the left front wheel and decreases the speed of the right front motor driving the right front wheel to correct the drift. Once the car enters a stable drift phase, the left and right front wheels maintain a differential rolling motion that matches the turning radius, following a circular motion.

[0108] In one possible embodiment, the control method specifically includes, during the process of controlling the rotational speed of the right rear motor driving the right rear wheel to be greater than the rotational speed of the left rear motor driving the left rear wheel, before the steering wheel turns to the right at an angle greater than zero, when the yaw rate of the electric vehicle 10 increases to a preset angular velocity, controlling the rotational speed of the left front motor driving the left front wheel to increase and controlling the rotational speed of the right front motor driving the right front wheel to decrease.

[0109] During drifting, the electric vehicle 10 continuously monitors its speed, yaw rate, and sideslip angle to determine its body posture. The elliptical safety boundaries for these parameters are calculated from the vehicle speed, and are obtained in real-time during drifting. When the yaw rate increases to a preset value, the vehicle enters its drift equilibrium point. Correction is then achieved by increasing the rotational speed of the left front motor driving the left front wheel and decreasing the rotational speed of the right front motor driving the right front wheel.

[0110] In one possible embodiment, controlling the left front motor to increase the speed of the left front wheel and controlling the right front motor to decrease the speed of the right front wheel specifically includes controlling the left front motor to increase the speed of the left front wheel and controlling the right front motor to decrease the speed of the right front wheel so that the steering wheel generates a force to turn to the right.

[0111] Once the drift equilibrium point is reached, the left front motor speed increases while the right front motor speed decreases, generating hand force on the steering wheel to assist the driver in timely counter-steering. The distributed drive system adjusts the speed difference between the two front axle motors, thereby generating hand force on the steering wheel, with the electric vehicle 10 indicating the timing and angle of counter-steering to the driver.

[0112] In one possible embodiment, the control method further includes, during the process of controlling the right rear motor to drive the right rear wheel to rotate at a speed greater than the left rear motor to drive the left rear wheel, when the angle of the steering wheel turning to the right continues to increase and is less than a second preset angle for a second preset duration, controlling the left front motor to drive the left front wheel to decrease the speed and controlling the right front motor to drive the right front wheel to increase the speed.

[0113] When the steering wheel turns to the right at an angle that continuously increases but is less than a second preset angle for a second preset duration, it indicates that the driver may be attempting to correct the vehicle's drift by counter-steering. However, the counter-steering angle is insufficient, requiring assistance from the electric vehicle 10 to maintain control. The distributed drive system responds to the driver's steering wheel input and dynamically adjusts the speed of the front axle motor. When the steering wheel turns to the right at an angle that continuously increases but is less than a second preset angle for a second preset duration, the distributed drive system actively controls the left front motor to reduce the speed of the left front wheel and the right front motor to increase the speed of the right front wheel. By reducing the speed of the left front wheel and increasing the speed of the right front wheel, the electric vehicle 10 can adjust the steering tendency of the front wheels, helping the vehicle maintain its drift state more smoothly and preventing it from exiting the drift state due to insufficient counter-steering.

[0114] In one possible embodiment, the control method further includes, during the process of controlling the speed of the right rear motor driving the right rear wheel to be greater than the speed of the left rear motor driving the left rear wheel, when the angle of the steering wheel turning to the right is less than a third preset angle, controlling the speed of both the right rear motor and the left rear motor to decrease and controlling the difference between the speeds of the right rear motor and the left rear motor to decrease.

[0115] For example, such as Figure 7As shown, before time t3, i.e., before the steering wheel turns to the right at an angle greater than zero, the speed of the left front motor driving the left front wheel is increased while the speed of the right front motor driving the right front wheel is decreased, so that the steering wheel generates a force to turn to the right, thus prompting the driver to counter-steer. At time t7, when the steering wheel turns to the right continuously increases and is less than the second preset angle for the second preset duration, i.e., the driver has already reached a balance state by counter-steering but continues to turn the steering wheel, excessive counter-steering will also cause the electric vehicle 10 to exit the drift state. Therefore, the speed of the left front motor driving the left front wheel is decreased while the speed of the right front motor driving the right front wheel is increased, so that the steering wheel generates a force to turn to the left, prompting the driver to reach a balance state. At time t6, the steering wheel turns to the right at an angle less than the third preset angle. The speeds of both the right and left rear motors are decreased, and the difference between the speeds of the right and left rear motors is reduced, causing the electric vehicle 10 to exit the drift state.

[0116] According to this embodiment, the front axle distributed drive assists the driver in drift counter-driving, reducing the difficulty of drifting operations and the risk of drift loss of control.

[0117] Figure 8 and Figure 9 This is a schematic diagram of the auxiliary drift control architecture and process provided in the embodiments of this application.

[0118] like Figure 8 As shown, the electric vehicle 10 calculates the elliptical safety boundaries of the vehicle's yaw rate and sideslip angle offline based on vehicle speed. It then sends the calculated preset yaw rate or sideslip angle to the vehicle controller. The yaw rate and sideslip angle safety boundaries are stored in the ROM. During drifting, the current safety boundaries are obtained in real-time based on the vehicle speed. After entering drift mode, the vehicle controller converts the driver's desired torque into an increment of motor speed according to the dynamic equation. It determines whether to drift based on the accelerator pedal opening and steering wheel angle. After recognizing the driver's drift intention, it obtains real-time vehicle status information, including real-time vehicle speed, yaw rate, and sideslip angle. By correcting the front and rear axle motor speeds, it maintains vehicle drift and prevents loss of control. The target motor speed is sent to the lower-level motor controller's near-loop control.

[0119] By recognizing the driver's drift intention, the target motor speed is corrected, and the target speed is simultaneously sent to the lower-level motor controller for near-end closed-loop control. This reduces latency and the probability of driver error causing the vehicle to lose control or exit the drift, enabling the electric vehicle 10 to drift stably. The vehicle controller transmits the calculated four-motor speed commands to the motor controller, which uses resolver sensor information for closed-loop control of the motor speed.

[0120] like Figure 9As shown, after the electric vehicle 10 activates drift mode, it determines whether it has entered drift mode. Upon entering drift mode, the motor controller enters a closed-loop speed control mode. The electric vehicle 10 identifies whether the driver intends to drift. If the driver intends to drift, the electric vehicle 10 actively adjusts the motor speed to quickly enter the slip threshold state. Once the electric vehicle 10 enters the drift state, it adjusts the rear axle speed to maintain the drift, while simultaneously adjusting the front axle motor to generate steering wheel force. When drifting to the left in a circle, upon detecting the driver's drift intention, it appropriately increases the right rear motor speed and appropriately decreases the left rear motor speed to quickly bring the electric vehicle 10 into the tail-swing threshold state. Upon reaching the drift equilibrium point, the left front motor speed increases, and the right front motor speed decreases, generating steering wheel force to assist the driver in timely counter-steering.

[0121] During drifting, if the electric vehicle 10 shows signs of losing control, the speed of the four motors is reduced to stabilize the vehicle. If the vehicle shows signs of fishtailing, the differential speed of the four motors is adjusted to generate a reverse yaw to help the driver avoid losing control. The system identifies whether the driver wants to exit the drift. If the driver does not want to exit the drift, and the driver releases the accelerator pedal to a degree less than a threshold, indicating a tendency for the electric vehicle 10 to exit the drift, the speed of the rear axle motor is increased to maintain the drift. If the driver counter-steering excessively and to a degree less than a threshold, indicating a tendency for the electric vehicle 10 to exit the drift, the differential speed of the front axle motor helps the driver reduce the probability of exiting the drift.

[0122] According to the solution of this application, when the electric vehicle 10 is drifting, the driver's drifting intention is identified by the accelerator pedal and steering wheel and the vehicle is controlled to enter the drift state. The torque expected by the driver is converted into an increment of the motor speed, and the target speed of the rear axle motor is corrected, making it easier for the electric vehicle 10 to drift. This reduces the probability of the vehicle losing control or exiting the drift due to driver misoperation, enabling the vehicle to drift stably. It also reduces the skill requirements of the driver for drifting operations and improves the driving experience and safety of the vehicle.

[0123] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for electric vehicles, characterized in that, During the operation of the electric vehicle, the control method is used to assist the electric vehicle in drifting by controlling the distributed drive system and steering system of the electric vehicle after the drift mode of the electric vehicle is activated. The control method includes: After the accelerator pedal opening of the electric vehicle is greater than the first preset opening and the steering wheel turns to the left by a greater than the first preset angle, and before the steering wheel turns to the right by a greater than zero angle, the speed at which the right rear motor drives the right rear wheel is controlled to be greater than the speed at which the left rear motor drives the left rear wheel. When the steering wheel is turned to the right at an angle greater than zero and less than a second preset angle, the speed at which the right rear motor drives the right rear wheel is controlled to be less than the speed at which the left rear motor drives the left rear wheel.

2. The control method according to claim 1, characterized in that, The control method further includes: During the process of controlling the right rear motor to drive the right rear wheel to be faster than the left rear motor to drive the left rear wheel, before the steering wheel turns to the right at an angle greater than zero, the left front motor to drive the left front wheel is controlled to increase its speed and the right front motor to drive the right front wheel is controlled to decrease its speed.

3. The control method according to claim 1 or 2, characterized in that, The control method specifically includes: During the process of controlling the right rear motor to drive the right rear wheel to be faster than the left rear motor to drive the left rear wheel, when the accelerator pedal opening is reduced to a second preset opening, the speeds of both the right and left rear motors are reduced, and the difference between the speeds of the right and left rear motors is reduced.

4. The control method according to claim 3, characterized in that, The control method further includes: During the process of controlling the right rear motor to drive the right rear wheel to be faster than the left rear motor to drive the left rear wheel, when the opening of the accelerator pedal is greater than the third preset opening and less than the first preset opening for a first preset duration, the speeds of both the right rear motor and the left rear motor are actively increased. Wherein, the third preset opening is less than the first preset opening and greater than the second preset opening.

5. The control method according to any one of claims 1-4, characterized in that, The control method further includes: During the process of controlling the right rear motor to drive the right rear wheel to rotate at a speed greater than the left rear motor to drive the left rear wheel, when the steering wheel is turned to the right at an angle greater than the second preset angle, the difference in speed between the right rear motor and the left rear motor is reduced.

6. The control method according to claim 5, characterized in that, The control method further includes: During the process of controlling the right rear motor to drive the right rear wheel to be faster than the left rear motor to drive the left rear wheel, when the steering wheel turns to the right at an angle that continues to increase and is less than the second preset angle for a second preset duration, the left front motor to drive the left front wheel is controlled to decrease and the right front motor to drive the right front wheel is controlled to increase.

7. The control method according to claim 1, characterized in that, The control of the right rear motor to drive the right rear wheel at a speed greater than the left rear motor to drive the left rear wheel specifically includes: During the process of turning the steering wheel to the left, the rate of increase of the right rear motor is controlled to be greater than the rate of increase of the left rear motor.

8. The control method according to claim 1, characterized in that, The control method further includes: During the process of turning the steering wheel back to the right, the speed of both the right rear motor and the left rear motor is reduced.

9. The control method according to claim 1, characterized in that, The control of the right rear motor to drive the right rear wheel at a speed lower than that of the left rear motor to drive the left rear wheel specifically includes: The speed of the right rear motor is reduced, and the speed of the left rear motor is increased.

10. The control method according to claim 9, characterized in that, The control method specifically includes: The rate at which the speed of the right rear motor decreases is less than the rate at which the speed of the left rear motor increases.

11. The control method according to claim 1 or 2, characterized in that, The control method specifically includes: During the process of controlling the right rear motor to drive the right rear wheel to be faster than the left rear motor to drive the left rear wheel, before the steering wheel turns to the right at an angle greater than zero, when the yaw rate of the electric vehicle increases to a preset angular velocity, the left front motor to drive the left front wheel is controlled to increase and the right front motor to drive the right front wheel is controlled to decrease.

12. The control method according to claim 11, characterized in that, The control of increasing the speed of the left front motor driving the left front wheel and decreasing the speed of the right front motor driving the right front wheel specifically includes: The left front motor drives the left front wheel at an increased speed, while the right front motor drives the right front wheel at a decreased speed, so that the steering wheel generates a force to turn to the right.

13. The control method according to claim 5, characterized in that, The control method further includes: During the process of controlling the right rear motor to drive the right rear wheel to rotate at a speed greater than the left rear motor to drive the left rear wheel, when the steering wheel is turned to the right at an angle less than a third preset angle, the speeds of both the right and left rear motors are reduced, and the difference between the speeds of the right and left rear motors is reduced.

14. A vehicle controller for electric vehicles, characterized in that, The vehicle controller is used to implement the control method as described in any one of claims 1-13.

15. An electric vehicle, characterized in that, The electric vehicle includes a distributed drive system, an accelerator pedal, and a steering wheel. The distributed drive system is used to implement the control method as described in any one of claims 1-13. The accelerator pedal is used to instruct the distributed drive system to output torque to the four wheels of the electric vehicle, and the steering wheel is used to instruct the steering angle of the wheels of the electric vehicle.

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