Control method and controller for non-inductive braking of electric vehicle and electric vehicle

Abstract

The invention provides a control method for non-inductive braking of an electric vehicle, a controller and the electric vehicle, and is applied to the technical field of electric vehicles so as to improve the comfort of the electric vehicle at the end of braking. According to the control method, before the speed of the electric vehicle is equal to the preset speed, the braking system is controlled to continuously brake the four wheels of the electric vehicle, and the torque output by the driving motor is controlled to be zero. And then, before the travel of the brake pedal is reduced to be smaller than the preset travel, a brake system is controlled to brake four wheels, and meanwhile, a driving motor is controlled to output compensation torque in the same rotating speed direction as the wheels. And then, before the brake pedal stroke is reduced to zero, the compensation torque output by the driving motor is controlled to be reduced along with reduction of the brake pedal stroke. On the basis, forward movement of the vehicle caused by overlarge compensation torque when the braking force of the wheels is reduced can be avoided, and the driving experience is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicles, and in particular to a control method for a sensorless braking of an electric vehicle, a controller and an electric vehicle. Background Art

[0002] In recent years, with the popularity of electric vehicles, in order to improve the user experience, the functions of electric vehicles have become more and more perfect. Among them, at the end of the braking of the electric vehicle, the electric vehicle will rebound due to the action of the tires and suspension after stopping, causing the electric vehicle to falter and cause discomfort. In order to achieve the effect of comfortable braking, during the braking process of the electric vehicle, the more common method is to deliberately reduce the braking force at the end of braking through the comfort braking algorithm or to control the deceleration of the electric vehicle through the comfort braking algorithm constructed by the wheel's rotary sensor signal. However, the above scheme is prone to the problem of the electric vehicle rushing forward when the brake pedal stroke changes, affecting the user's driving experience. Summary of the invention

[0003] The embodiments of the present application provide a control method, a controller and an electric vehicle for the sensorless braking of an electric vehicle, so as to control the drive motor to adjust the output compensation torque during the comfortable braking process of the electric vehicle, thereby preventing the electric vehicle from rushing forward while achieving comfortable braking and improving the driving experience of the user.

[0004] In order to achieve the above objectives, the embodiments of the present application provide the following technical solutions.

[0005] In the first aspect, the embodiment of the present application provides a control method for the senseless braking of an electric vehicle, wherein the control method is used to control the drive motor to output a compensating torque during the braking process of the electric vehicle to reduce the setback of the electric vehicle during the braking process, wherein the control method includes: after the first moment when the brake pedal stroke increases from zero and before the second moment when the brake system brakes to the speed of the electric vehicle equal to the preset speed, the brake system is controlled to continuously brake the four wheels of the electric vehicle and the torque output by the drive motor is controlled to be zero. After the second moment and before the third moment when the brake pedal stroke is reduced to equal to the preset stroke, the brake system is controlled to continue braking the four wheels and the drive motor is controlled to output a compensating torque in the same direction as the rotation speed of the four wheels. After the third moment and before the fourth moment when the brake pedal stroke is reduced to zero, the braking force output by the brake system to the four wheels is controlled to decrease as the brake pedal stroke decreases and the compensating torque output by the drive motor is controlled to begin to decrease.

[0006] During the braking process, before the braking system brakes until the speed of the electric vehicle equals the preset speed, it indicates that the electric vehicle is not yet in the final stage of braking. At this time, the electric vehicle can normally brake the four wheels through the braking system, and the drive motor does not need to output torque. When the speed of the electric vehicle equals the preset speed and the braking pedal travel is greater than the preset travel, it indicates that the deceleration of the electric vehicle is too large. While the braking system brakes the four wheels, controlling the drive motor to output a compensation torque in the same direction as the rotational speed of the wheels can provide driving force for the electric vehicle to reduce the deceleration of the electric vehicle, so that the electric vehicle decelerates more smoothly and improves the comfort during braking in the final stage of braking. Then, when the braking pedal travel decreases, it indicates that the driver is releasing the braking pedal. At this time, keeping the drive torque output by the drive motor unchanged will cause the difference between the driving force provided by the drive motor and the braking force provided by the braking system to increase, resulting in a rapid decrease in the deceleration of the electric vehicle and causing the electric vehicle to lunge forward. In the embodiment of the present application, the compensation torque output by the drive motor also decreases when the braking pedal travel decreases in the final stage of braking. Based on this, it is possible to avoid the vehicle lunging forward due to excessive compensation torque when the braking force of the wheels decreases, and further improve the driving and riding experience.

[0007] In one embodiment, the above control method further includes: after the third moment and before the fourth moment, controlling the compensation torque output by the drive motor to decrease to zero.

[0008] In the above embodiment, the compensation torque output by the drive motor decreases to zero before the fourth moment when the braking pedal travel decreases to zero, which can enable the electric vehicle to be quickly braked by the braking system when approaching a stop, and avoid the electric vehicle having too long a braking distance.

[0009] In one embodiment, the above control method further includes: before the speed of the electric vehicle decreases to zero, controlling the compensation torque output by the drive motor to decrease to zero.

[0010] In the above embodiment, before the speed of the electric vehicle decreases to zero, the compensation torque output by the drive motor decreases to zero can also enable the electric vehicle to be quickly braked by the braking force output by the braking system, and avoid the electric vehicle having too long a braking distance.

[0011] In one embodiment, after the third moment and before the fourth moment, the decreasing rate of the braking pedal travel is greater than the preset decreasing rate.

[0012] When the reduction rate of the brake pedal stroke is greater than the preset reduction rate, it indicates that the driver is quickly releasing the brake pedal. At this time, when the braking force output by the braking system to the four wheels decreases and the compensation torque output by the drive motor remains unchanged, the deceleration of the electric vehicle will decrease too quickly, causing the electric vehicle to lurch forward. Through the above implementation manner, the reduction of the compensation torque output by the drive motor when the braking force output by the braking system to the four wheels decreases can avoid the too rapid decrease of the deceleration, so that the electric vehicle can decelerate more smoothly.

[0013] In one implementation manner, the above control method further includes: after the third moment and before the fourth moment, controlling the compensation torque output by the drive motor to decrease as the brake pedal stroke decreases.

[0014] In the above implementation, the compensation torque output by the drive motor decreasing as the brake pedal stroke decreases can make the braking force output by the braking system to the four wheels and the driving force provided by the compensation torque output by the drive motor remain balanced, so that the electric vehicle can decelerate more smoothly.

[0015] In one implementation manner, the above control method further includes: during the process of controlling the compensation torque output by the drive motor to decrease as the brake pedal stroke decreases, the greater the reduction rate of the brake pedal stroke, the greater the reduction rate of the compensation torque output by the drive motor.

[0016] When the reduction rate of the brake pedal stroke is greater, the reduction rate of the braking force output by the braking system to the four wheels is faster. At this time, if the reduction rate of the compensation torque output by the drive motor is too slow, it will still cause the deceleration of the electric vehicle to decrease too quickly, resulting in the vehicle lurching forward. In the above implementation, the greater the reduction rate of the brake pedal stroke, the greater the reduction rate of the compensation torque output by the drive motor can make the braking force output by the braking system to the four wheels and the compensation torque output by the drive motor remain balanced, so that the electric vehicle can decelerate more smoothly and avoid the electric vehicle from lurching forward.

[0017] In one implementation manner, the above control method further includes: after the second moment, when the gear of the electric vehicle is switched from the forward gear to the reverse gear or the parking gear, controlling the compensation torque output by the drive motor to decrease.

[0018] When the gear of the electric vehicle is switched from the forward gear to the reverse gear or the parking gear after the second moment, the electric vehicle has not come to a complete stop yet. At this time, the compensation torque output by the drive motor will cause an impact on the electric vehicle, resulting in the electric vehicle being unable to respond to the operations after shifting gears in a timely manner. In the above implementation, when the gear of the electric vehicle is switched from the forward gear to the reverse gear or the parking gear, the compensation torque output by the drive motor needs to decrease quickly, which can avoid causing an impact on the electric vehicle and enable the electric vehicle to respond to the operations after shifting gears in a timely manner.

[0019] In one embodiment, the above control method further includes: after the second moment and before the third moment, controlling the compensation torque output by the drive motor to change with the deceleration of the electric vehicle.

[0020] When the deceleration of the electric vehicle changes, keeping the compensation torque output by the drive motor unchanged will cause the electric vehicle to decelerate unevenly. Therefore, when controlling the compensation torque output by the drive motor at the end of braking, the compensation torque output by the drive motor needs to change with the change of the deceleration of the electric vehicle to ensure that the electric vehicle can decelerate smoothly.

[0021] In one embodiment, during the process of controlling the compensation torque output by the drive motor to change with the deceleration of the electric vehicle, it is necessary to control the compensation torque output by the drive motor to increase with the increase of the deceleration of the electric vehicle and control the compensation torque output by the drive motor to decrease with the decrease of the deceleration of the electric vehicle.

[0022] Based on this, when the deceleration of the electric vehicle increases, increasing the compensation torque output by the drive motor can reduce the deceleration of the electric vehicle and prevent the deceleration of the electric vehicle from being too large, causing the passengers to lean forward. When the deceleration of the electric vehicle decreases, reducing the compensation torque output by the drive motor can prevent the deceleration of the electric vehicle from decreasing too quickly and prevent the electric vehicle from surging forward.

[0023] In one embodiment, the above control method further includes: after the second moment and before the third moment, when the difference between the deceleration of the electric vehicle indicated by the resolver sensor of the drive motor and the deceleration of the electric vehicle indicated by the acceleration sensor is greater than a preset difference, controlling the compensation torque output by the drive motor according to the deceleration of the electric vehicle indicated by the acceleration sensor.

[0024] After the second moment and before the third moment, the electric vehicle is in the end stage of braking. At this time, the difference between the deceleration of the electric vehicle indicated by the resolver sensor of the drive motor and the deceleration of the electric vehicle indicated by the acceleration sensor being greater than the preset difference indicates that the wheels of the electric vehicle are slipping. At this time, the deceleration of the electric vehicle indicated by the acceleration sensor is more accurate. Based on this, controlling the compensation torque output by the drive motor according to the deceleration of the electric vehicle indicated by the acceleration sensor can control the compensation torque output by the drive motor more accurately and prevent the electric vehicle from surging forward.

[0025] In one embodiment, the above control method further includes: after the second moment and before the third moment, when the braking system outputs a greater braking force to the two front wheels than to the two rear wheels, controlling the compensation torque output by the front drive motor to be greater than the compensation torque output by the rear drive motor.

[0026] The braking force output by the braking system to the two front wheels is greater than the braking force output to the two rear wheels, indicating that the electric vehicle is braking during forward travel. At this time, the center of gravity of the electric vehicle moves forward. Only when the braking force output by the two front wheels is greater than the braking force output to the two rear wheels can the electric vehicle decelerate more effectively. In this case, the compensation torque output by the front drive motor being greater than the compensation torque output by the rear drive motor can make the deceleration of the two front wheels and the two rear wheels consistent, thereby controlling the electric vehicle to decelerate more smoothly.

[0027] In one embodiment, the above control method further includes: after the third moment and before the fourth moment, controlling the front drive motor to reduce the output front drive compensation torque while controlling the rear drive motor to reduce the output rear drive compensation torque.

[0028] In the above implementation, controlling the front drive motor to reduce the output front drive compensation torque while controlling the rear drive motor to reduce the output rear drive compensation torque can make the deceleration of the two front wheels and the deceleration of the two rear wheels consistent, thereby controlling the electric vehicle to decelerate more smoothly.

[0029] In one embodiment, the above control method further includes: after the third moment and before the fourth moment, when the steering angle of the steering wheel of the electric vehicle turns left by more than a preset angle, controlling the compensation torque output by the drive motor on the left side of the electric vehicle to be less than the compensation torque output by the drive motor on the right side.

[0030] In the above implementation, after the third moment and before the fourth moment, the steering angle of the steering wheel of the electric vehicle turning left by more than a preset angle indicates that the electric vehicle needs to turn left. In this scenario, the rotational speed of the left wheel is less than the rotational speed of the right wheel. Therefore, when the wheels on both sides of the electric vehicle are driven by different drive motors, the compensation torque output by the drive motor on the left side needs to be less than the compensation torque output by the drive motor on the right side to ensure the vehicle can drive smoothly.

[0031] In a second aspect, an embodiment of the present application provides a controller for an electric vehicle, which is used to control the electric vehicle during the braking process of the electric vehicle to implement the control method in any one of the above first aspects.

[0032] In one embodiment, the above controller is further used to: after the second moment and before the third moment, when the difference between the deceleration indicated by the resolver sensor of the drive motor and the deceleration indicated by the acceleration sensor of the electric vehicle is greater than a preset difference, control the compensation torque output by the drive motor according to the deceleration indicated by the acceleration sensor of the electric vehicle.

[0033] In a third aspect, an embodiment of the present application provides an electric vehicle, which uses the control method in any one of the embodiments of the first aspect to control the output compensation torque of the driving motor of the electric vehicle during the braking process of the electric vehicle.

[0034] Based on the technical principles and beneficial effects of the first aspect, the controller of the second aspect and the electric vehicle of the third aspect can also prevent the electric vehicle from rushing forward while performing comfortable braking, thereby improving the user's driving experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0036] Figure 2 Another schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0037] Figure 3 Another schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0038] Figure 4 Another schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0039] Figure 5 Another schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0040] Figure 6 Another schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0041] Figure 7 Another schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0042] Figure 8 A schematic diagram of the braking process of an electric vehicle without a sense of braking provided in an embodiment of the present application;

[0043] Figure 9 Another schematic diagram of the braking process of the electric vehicle without a sense of braking provided in an embodiment of the present application;

[0044] Figure 10 Another schematic diagram of the braking process of the electric vehicle without a sense of braking provided in an embodiment of the present application;

[0045] Figure 11 Another schematic diagram of the braking process of the electric vehicle without a sense of braking provided in an embodiment of the present application;

[0046] Figure 12 Another schematic diagram of the braking process of the electric vehicle without a sense of braking provided in an embodiment of the present application;

[0047] Figure 13 Another schematic diagram of the braking process of an electric vehicle with a senseless brake provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0049] It should be noted that "in one embodiment" in this application is used to indicate an example, illustration or description. The solution described as "in one embodiment" in this application should not be interpreted as being more preferred or more advantageous than the solutions of other embodiments. Specifically, the use of "in one embodiment" is intended to present the inventive concept of this application in a specific way.

[0050] With the development of electric vehicles, the driving experience of electric vehicles has received more and more attention. Among them, the braking performance of electric vehicles is one of the key factors affecting the driving experience of electric vehicles. During the braking process of electric vehicles, the end of braking refers to the process in which the speed of the electric vehicle decreases from very small to zero, that is, the process in which the electric vehicle stops completely and has no relative movement with the ground. During the braking process of electric vehicles, the suspension of the car is compressed under the action of deceleration. After the braking of the car, although the vehicle has actually stopped, the body of the car will rebound under the action of the suspension, causing the car to jerk and affect the user's driving experience.

[0051] At the end of braking of an electric vehicle, in order to reduce the jerk of the electric vehicle and make the braking process more comfortable, some related technologies reduce the braking force of the braking device at the end of braking to control the deceleration of the electric vehicle to decrease smoothly to zero. However, the above scheme has a slow response speed. Other related technologies control the compensating torque output by the drive motor through the resolver sensor signal of the drive motor at the end of braking to control the deceleration of the electric vehicle to decrease more smoothly to zero. However, the above scheme needs to rely on the resolver sensor signal. When the driver quickly releases the brake, the resolver sensor signal of the drive motor cannot be represented in time, resulting in poor availability of comfortable braking.

[0052] During the comfortable braking process of an electric vehicle, if the driver releases the brake pedal at the end of braking, the brake pedal stroke will be reduced, thereby reducing the braking force of the electric vehicle. The reduction in the braking force of the electric vehicle will lead to a reduction in the deceleration of the electric vehicle, causing the electric vehicle to move forward and cause discomfort. Therefore, how to improve the comfort of the braking process when the brake pedal stroke changes during the comfortable braking process of the electric vehicle has become an urgent problem to be solved.

[0053] In order to solve the above problems, the embodiment of the present application provides a control method, a controller and an electric vehicle for the senseless braking of an electric vehicle. Among them, the control method for the senseless braking of an electric vehicle provided by the embodiment of the present application is used to control the drive motor to output a compensating torque during the braking process of the electric vehicle to reduce the setback of the electric vehicle during the braking process. The control method includes: after the first moment when the brake pedal stroke increases from zero and before the second moment when the brake system brakes to the speed of the electric vehicle equal to the preset speed, the brake system is controlled to continuously brake the four wheels and control the torque output by the drive motor to be zero. After the second moment and before the third moment when the brake pedal stroke is reduced to equal to the preset stroke, the brake system is controlled to continue to brake the four wheels and control the drive motor to output a compensating torque in the same direction as the rotation speed of the four wheels. After the third moment and before the fourth moment when the brake pedal stroke is reduced to zero, the braking force output by the brake system to the four wheels is controlled to decrease as the brake pedal stroke decreases and the compensating torque output by the drive motor is controlled to begin to decrease.

[0054] The control method provided in the embodiment of the present application can control the drive motor to output a compensating torque before the speed of the electric vehicle decreases to less than the preset speed and the brake pedal stroke decreases to the preset stroke, so as to reduce the deceleration of the electric vehicle by increasing the driving force, thereby performing comfortable braking on the electric vehicle. Then, during the comfortable braking process, when the brake pedal stroke of the electric vehicle decreases to the preset stroke and the brake pedal stroke continues to decrease, the compensating torque output by the drive motor is controlled to decrease, so as to avoid the electric vehicle from jumping forward due to excessive compensating torque, thereby improving the comfort of the electric vehicle during comfortable braking at the end of braking.

[0055] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0056] Figure 1 A schematic diagram of an electric vehicle provided in an embodiment of the present application. Figure 1 As shown, the electric vehicle 10 includes a drive system 100, a brake system 200, a power battery 300 and a controller 400. The drive system 100 is used to drive the wheels of the electric vehicle 10 to rotate so as to drive the electric vehicle 10 to travel. The brake system 200 is used to brake the four wheels of the electric vehicle 10 to decelerate the electric vehicle 10. The power battery 300 is used to power the drive system 100 and the brake system 200. The controller 400 is used to control the brake system 200 to brake the four wheels respectively and control the drive system 100 to output a compensation torque to drive the wheels to rotate.

[0057] Figure 2 Another schematic diagram of an electric vehicle provided in an embodiment of the present application. Figure 2As shown, in one embodiment, the drive system 100 includes a motor controller 110 (motor control unit, MCU), a drive motor 120, and a speed reducer 130. The motor controller 110 is configured to receive direct current output by the power battery 300 and output alternating current to control the torque output by the drive motor 120. The torque output by the drive motor 120 drives the wheels of the electric vehicle 10 to rotate through the speed reducer 130. The braking system 200 includes a plurality of wheel-end braking devices 210, and the plurality of wheel-end braking devices 210 are configured to brake the plurality of wheels of the electric vehicle 10 respectively.

[0058] After the user steps on the brake pedal to output a braking signal or the autonomous driving system outputs a braking signal, the controller 400 controls the wheel-end braking device 210 to brake the wheels according to the received braking signal, so that the electric vehicle 10 decelerates. Among them, when braking the electric vehicle 10, the braking of the electric vehicle 10 includes emergency braking and non-emergency braking. Emergency braking is a process of decelerating the electric vehicle 10 to a stop within the shortest distance in an extremely short time. During emergency braking, the deceleration of the electric vehicle 10 is relatively large, so that the electric vehicle 10 can be quickly braked to a stop within the shortest distance. The non-emergency braking process is a process of controlling the electric vehicle 10 to slowly decelerate to a stop over a longer period of time. During the non-emergency braking process, the deceleration of the electric vehicle 10 is relatively small, so that the electric vehicle 10 can be slowly braked to a stop through a longer braking distance.

[0059] In one embodiment, the wheel-end braking device 210 is an electromechanical brake (EMB), an electronic hydraulic brake (EHB), or other types of braking devices, and the embodiments of the present application do not make limitations.

[0060] After the user steps on the accelerator pedal of the electric vehicle 10 to output an acceleration indication signal, the controller 400 is further configured to control the motor controller 110 in the drive system 100 to adjust the torque output by the drive motor 120 according to the acceleration indication signal. At the end of the braking period of the non-emergency braking process, the controller 400 can also control the drive motor 120 to output a compensation torque in the same direction as the rotational speed of the wheels to perform comfortable braking on the electric vehicle 10.

[0061] In one embodiment, still as Figure 2 shown, the electric vehicle 10 further includes a vehicle speed measurement unit 140. The vehicle speed measurement unit 140 is configured to detect the vehicle speed of the electric vehicle 10. The controller 400 can detect the vehicle speed through the vehicle speed measurement unit 140 and control the drive motor 120 to output a compensation torque during braking to perform comfortable braking on the electric vehicle 10. Among them, the vehicle speed measurement unit 140 is a wheel speed sensor or a resolver sensor.

[0062] In one embodiment, still as Figure 2 shown, the electric vehicle 10 further includes an inertial measurement unit 150. Among them, the inertial measurement unit 150 can detect the deceleration of the electric vehicle 10. The controller 400 can adjust the compensation torque output by the drive motor 120 during the comfortable braking process by detecting the deceleration through the inertial measurement unit 150.

[0063] In one embodiment, the vehicle speed measurement unit 140 and the inertial measurement unit 150 are communicatively connected to the controller 400 through the braking system 200. Of course, the vehicle speed measurement unit 140 and the inertial measurement unit 150 can also be directly communicatively connected to the controller 400 through a communication bus or communicatively connected to the controller 400 through the drive system 100.

[0064] In one embodiment, the controller 400 is a central controller or a vehicle control unit (VCU) in the electric vehicle 10 or a domain control unit (DCU). In addition, the number of drive systems 100 in the electric vehicle 10 is arranged according to the driving mode of the electric vehicle 10.

[0065] Figure 3 Another schematic diagram of the electric vehicle provided by the embodiment of the present application. In one embodiment, the two wheels corresponding to the front axle 220 of the electric vehicle 10 are the left front wheel FL and the right front wheel FR, and the two wheels corresponding to the rear axle 230 of the electric vehicle 10 are the left rear wheel RL and the right rear wheel RR. As Figure 3 shown, the electric vehicle 10 includes a drive system 100, and the drive system 100 includes a drive motor 120 and a motor controller 110. Among them, when the electric vehicle 10 is a front-wheel drive vehicle, the drive system 100 is used to drive the left front wheel FL and the right front wheel FR on the front axle 220 of the electric vehicle 10. In addition, the electric vehicle 10 includes four wheel-end braking devices 210. Among them, two wheel-end braking devices 210 are respectively used to brake the left front wheel FL and the right front wheel FR of the electric vehicle 10. The other two wheel-end braking devices 210 are respectively used to brake the left rear wheel RL and the right rear wheel RR of the electric vehicle 10.

[0066] In one embodiment, when the electric vehicle 10 is a rear-wheel drive vehicle, the drive system 100 can also be used to drive the left rear wheel RL and the right rear wheel RR of the electric vehicle 10.

[0067] Figure 4 Another schematic diagram of the electric vehicle provided by the embodiment of the present application. In one embodiment, the electric vehicle 10 includes two drive systems 100, and each drive system 100 includes a drive motor 120 and a motor controller 110. Among them, as Figure 4As shown, the above two drive systems 100 are respectively used to drive the left front wheel FL and the right front wheel FR of the electric vehicle 10, so that the left front wheel FL and the right front wheel FR can be independently controlled.

[0068] In one embodiment, the above two drive systems 100 can also be respectively used to drive the left rear wheel RL and the right rear wheel RR of the electric vehicle 10, so that the left rear wheel RL and the right rear wheel RR can be independently controlled.

[0069] Figure 5 Another schematic diagram of the electric vehicle provided by the embodiment of the present application. In one embodiment, as Figure 5 shown, the electric vehicle 10 includes two drive systems 100, and each drive system 100 includes a drive motor 120 and a motor controller 110. Among them, one drive system 100 drives the left front wheel FL and the right front wheel FR of the electric vehicle 10, and the other drive system 100 drives the left rear wheel RL and the right rear wheel RR of the electric vehicle 10.

[0070] Figure 6 Another schematic diagram of the electric vehicle provided by the embodiment of the present application. In one embodiment, as Figure 6 shown, the electric vehicle 10 includes three drive systems 100. Among them, one drive system 100 is used to drive the left front wheel FL and the right front wheel FR of the electric vehicle 10. The other two drive systems 100 are respectively used to drive the left rear wheel RL and the right rear wheel RR of the electric vehicle 10.

[0071] In one embodiment, the electric vehicle 10 can also drive the left rear wheel RL and the right rear wheel RR through one drive system 100, and drive the left front wheel FL and the right front wheel FR of the electric vehicle 10 respectively through the other two drive systems 100.

[0072] Figure 7 Another schematic diagram of the electric vehicle provided by the embodiment of the present application. In one embodiment, as Figure 7 shown, the electric vehicle 10 includes four drive systems 100. Among them, the first drive system 100 is used to drive the left rear wheel RL of the electric vehicle 10, the second drive system 100 is used to drive the right rear wheel RR of the electric vehicle 10, the third drive system 100 is used to drive the left front wheel FL of the electric vehicle 10, and the fourth drive system 100 is used to drive the right front wheel FR of the electric vehicle 10.

[0073] After the driver steps on the brake pedal to output a brake signal or the autonomous driving system actively outputs a brake signal, the controller 400 can control the four wheel-end braking devices 210 to output braking forces to the corresponding wheels to control the deceleration of the electric vehicle 10. During the braking process of the electric vehicle 10, the greater the brake pedal travel, the greater the braking forces output by the four wheel-end braking devices 210, and the faster the electric vehicle 10 decelerates.

[0074] In some embodiments, the electric vehicle 10 also has an energy recovery function. Energy recovery means that when the electric vehicle 10 is in a braking state, the wheels drive the drive motor 120 to rotate, the drive motor 120 operates in a power generation state and outputs a torque opposite to the rotational speed direction of the wheels, the drive motor 120 converts the kinetic energy of the electric vehicle 10 into electrical energy, and the drive motor 120 can also provide a braking force for the electric vehicle 10 while generating electricity.

[0075] The braking mode of the electric vehicle 10 is divided into emergency braking and non-emergency braking. Emergency braking can be understood as a braking process that quickly decelerates the electric vehicle 10. During the emergency braking process, the deceleration of the electric vehicle 10 is relatively large. Non-emergency braking can be understood as a braking process that slowly decelerates the electric vehicle 10. During the non-emergency braking process, the deceleration of the electric vehicle 10 is relatively small. Whether the braking of the electric vehicle 10 is emergency braking or non-emergency braking can be determined according to the deceleration of the electric vehicle 10, the brake pedal travel, etc.

[0076] In one embodiment, if the deceleration of the electric vehicle 10 during the braking process of the electric vehicle 10 is greater than a preset deceleration, the braking mode of the electric vehicle 10 is emergency braking. If the deceleration of the electric vehicle 10 during the braking process of the electric vehicle 10 is less than or equal to the preset deceleration, the braking mode of the electric vehicle 10 is non-emergency braking. Exemplarily, the preset deceleration is 5m / s 2 。

[0077] In one embodiment, if the brake pedal travel of the electric vehicle 10 during the braking process of the electric vehicle 10 is greater than a travel threshold, the braking mode of the electric vehicle 10 is emergency braking. If the pedal travel of the electric vehicle 10 during the braking process of the electric vehicle 10 is less than or equal to the travel threshold, the braking mode of the electric vehicle 10 is non-emergency braking. Exemplarily, the above travel threshold can be 40% of the maximum travel of the brake pedal.

[0078] If the braking mode of the electric vehicle 10 is emergency braking, the braking efficiency and braking safety of the electric vehicle 10 are prioritized, that is, when the braking mode of the electric vehicle 10 is emergency braking, the electric vehicle 10 is to be stopped quickly according to the braking force indicated by the controller 400. If the braking mode of the electric vehicle 10 is non-emergency braking, the braking comfort and driving experience of the electric vehicle 10 are to be considered, that is, the settling of the electric vehicle 10 at the end of braking is to be reduced as much as possible. The controller 400 provided in an embodiment of the present application controls the drive motor 120 to output a compensating torque at the end of braking of the electric vehicle 10 to reduce the total braking force of the electric vehicle 10, thereby reducing the deceleration of the electric vehicle and improving braking comfort. The control method for the senseless braking of an electric vehicle provided in the present application is suitable for non-emergency braking scenarios.

[0079] During the braking process of an electric vehicle, the terminal stage of braking refers to the process in which the speed of the electric vehicle 10 changes from very small to completely zero. In the early and middle stages of braking, the suspension and tires of the electric vehicle 10 are compressed under the action of the braking deceleration. At the end of braking, the suspension and tires will rebound, causing the electric vehicle to stall. In one embodiment, during the braking process of the electric vehicle 10, the speed of the electric vehicle 10 is less than or equal to the preset speed, and the electric vehicle 10 is at the terminal stage of braking. In one embodiment, during the braking process of the electric vehicle 10, the speed of the drive motor 120 is less than the preset speed, and the electric vehicle 10 is at the terminal stage of braking.

[0080] During the braking process of the electric vehicle 10, when the speed of the electric vehicle 10 decreases to less than or equal to the preset speed, it indicates that the electric vehicle 10 is at the end of non-emergency braking. At this time, the reduction in the brake pedal stroke of the electric vehicle 10 will cause the wheel-end brake device 210 to provide a reduced braking force for the wheel. If the compensation torque output by the drive motor 120 remains unchanged, the deceleration of the electric vehicle 10 will decrease too quickly, causing the electric vehicle 10 to rush forward. Therefore, it is necessary to reduce the compensation torque output by the drive motor 120 when the brake pedal stroke decreases at the end of braking to prevent the electric vehicle 10 from rushing forward, thereby improving the user's driving experience.

[0081] In the process of controlling the drive motor 120 to reduce the output compensation torque, the resistance of the electric vehicle 10 may change due to external factors such as the road slope, the road adhesion coefficient, and the rate at which the driver releases the brake pedal.

[0082] In one embodiment, in the process of controlling the compensating torque output by the drive motor 120 to be reduced to zero, the controller 400 can also adjust the compensating torque output by the drive motor 120 according to the brake pedal travel reduction rate, the road adhesion coefficient and the road slope, so that the electric vehicle 10 can decelerate to a stop more smoothly.

[0083] In the process of controlling the compensation torque output by the drive motor 120 to decrease to zero, if the gear position of the electric vehicle 10 does not change, the controller 400 controls the drive motor 120 to reduce the output compensation torque according to the preset torque reduction rate, thereby smoothly decelerating the electric vehicle 10 to a stop. However, when the gear position of the electric vehicle 10 changes, the compensation torque output by the drive motor 120 remains unchanged, which still causes the electric vehicle 10 to rush forward.

[0084] In one embodiment, the controller 400 can also control the drive motor 120 to reduce the output compensation torque at a rate greater than a preset torque reduction rate when the gear of the electric vehicle 10 changes, thereby reducing the compensation torque output by the drive motor 120 more quickly and preventing the electric vehicle 10 from rushing forward.

[0085] In order to facilitate understanding of the control method, controller and electric vehicle for the senseless braking of an electric vehicle provided in the embodiment of the present application, the control method, controller and electric vehicle for the senseless braking of an electric vehicle provided in the embodiment of the present application are described below in combination with the first moment t1, the second moment t2, the third moment t3 and the fourth moment t4 during the comfortable braking process of the electric vehicle 10. Among them, the first moment t1 indicates that the brake pedal stroke increases from zero, the second moment t2 indicates that the speed of the electric vehicle 10 decreases to a preset speed, the third moment t3 indicates that the brake pedal stroke decreases to a preset stroke, and the fourth moment t4 indicates that the brake pedal stroke decreases to zero.

[0086] Figure 8 A schematic diagram of the braking process of an electric vehicle with a senseless brake provided in an embodiment of the present application. Figure 9 A schematic diagram of a braking process of an electric vehicle without a sense of braking provided in an embodiment of the present application. Figure 8 and Figure 9 As shown, when the electric vehicle 10 performs non-emergency braking, at the first moment t1, the brake pedal stroke increases from zero, and the brake system 200 starts to output braking force to the four wheels. After the first moment t1, the brake pedal stroke gradually increases, the brake system 200 continues to brake the four wheels of the electric vehicle 10, the speed of the electric vehicle 10 continues to decrease, and the torque output by the drive motor 120 is zero.

[0087] At a second moment t2 after the first moment t1, when the vehicle speed of the electric vehicle 10 decreases to be less than or equal to a preset vehicle speed V1, it indicates that the electric vehicle 10 is in the late stage of braking. Subsequently, the driver releases the brake pedal in the late stage of braking. At a third moment t3 after the second moment t2, when the brake pedal travel decreases to be equal to a preset travel, it indicates that the deceleration of the electric vehicle 10 is small. Between the second moment t2 and the third moment t3, the vehicle speed of the electric vehicle 10 is low, that is, the electric vehicle 10 is already in the late stage of braking at this time. At this time, the controller 400 controls the braking system 200 to continue braking the four wheels and controls the drive motor 120 to output a compensation torque in the same rotation direction as the rotation speeds of the four wheels, so as to provide driving force for the electric vehicle 10 through the compensation torque output by the drive motor 120 to reduce the deceleration of the electric vehicle 10 and control the electric vehicle 10 to decelerate more smoothly. That is to say, in the late stage of braking, the compensation torque reduces the deceleration of the electric vehicle 10, thereby avoiding the "braking nod" phenomenon caused by the rebound of the suspension after compression due to a large deceleration in the late stage of braking, reducing the jerks generated in the late stage of braking, and improving the riding comfort.

[0088] Among them, the above-mentioned compensation torque can be comprehensively determined according to various parameters such as the weight of the electric vehicle, the slope of the road surface, and the adhesion coefficient of the road surface. In the embodiment of the present application, between the second moment t2 and the third moment t3 during the braking process of the electric vehicle 10, the controller 400 can provide driving force for the wheels by actively controlling the drive motor 120 to output a compensation torque, so as to reduce the deceleration of the electric vehicle 10 in the late stage of non-emergency braking to perform comfortable braking on the electric vehicle 10.

[0089] At a fourth moment t4 after the third moment t3, when the brake pedal travel decreases to zero, it indicates that the braking force output by the braking system 200 is zero. Between the third moment t3 and before the fourth moment t4, the controller 400 controls the braking force output by the braking system 200 to the four wheels to decrease as the brake pedal travel decreases and controls the compensation torque output by the drive motor 120 to start decreasing. Among them, the controller 400 can control the drive motor 120 to decrease the output compensation torque according to a preset torque decrease rate.

[0090] In the embodiment of the present application, before the electric vehicle 10 reaches the end stage of braking, the controller 400 controls the braking system 200 to continuously brake the four wheels of the electric vehicle 10 to reduce the speed of the electric vehicle 10. When the travel of the brake pedal is greater than the preset travel after the electric vehicle 10 reaches the end stage of braking, the deceleration of the electric vehicle 10 is greater than the preset deceleration. At this time, the controller 400 controls the drive motor 120 to output a compensation torque in the same rotational speed direction as the four wheels to provide a driving force for the electric vehicle 10, thereby reducing the deceleration of the electric vehicle 10 and enabling the electric vehicle 10 to decelerate more smoothly. Finally, when the travel of the brake pedal decreases after the travel of the brake pedal is less than or equal to the preset travel after the end stage of braking, the compensation torque output by the drive motor starts to decrease. Based on this, it is possible to avoid the driving torque output by the drive motor 120 being too large when the travel of the brake pedal decreases, resulting in a further decrease in the deceleration of the electric vehicle 10 and causing the electric vehicle 10 to lurch forward.

[0091] In one embodiment, after the third moment t3 and before the fourth moment t4, the controller 400 can calculate the target deceleration of the electric vehicle 10 according to the vehicle speed detected by the vehicle speed measurement unit 140 and the actual deceleration of the electric vehicle 10 detected by the inertial measurement unit 150. Then, the controller 400 corrects the target deceleration according to the deviation between the target deceleration of the electric vehicle 10 and the actual deceleration. Next, the controller 400 calculates the torque reduction value according to the deviation between the corrected target deceleration and the actual deceleration. Finally, the controller 400 obtains the compensation torque at the current moment according to the compensation torque at the previous moment and the above torque reduction value.

[0092] In one embodiment, the vehicle speed of the electric vehicle 10 can be obtained based on the resolver signal of the resolver sensor. The actual deceleration of the electric vehicle can also be obtained by differentiating the vehicle speed. In addition, because the resistance received by the electric vehicle 10 varies under different road conditions, the calculation method of the target deceleration can be obtained through the experimental method. For example, by performing multiple tests, a comfortable braking deceleration curve of the electric vehicle 10 under different vehicle speeds, different weights, and different road surface adhesion coefficients is plotted. During the braking process, the target deceleration of the electric vehicle 10 is obtained based on the comfortable braking deceleration curve, and the compensation torque of the drive motor 120 is reduced according to the target deceleration.

[0093] Through the above method, when there is a deviation between the target deceleration and the actual deceleration, by correcting the target deceleration of the electric vehicle 10, it is possible to ensure that the compensation torque output by the drive motor 120 better meets the requirements of comfortable braking and further improves the driving experience of users.

[0094] After the third moment t3, as the brake pedal travel decreases, the compensation torque output by the drive motor 120 also decreases. However, when the brake pedal travel decreases to zero, if the compensation torque output by the drive motor 120 does not decrease to zero, it will cause the electric vehicle 10 to continue moving forward under the driving force provided by the compensation torque, resulting in an excessive braking distance of the electric vehicle 10.

[0095] In one embodiment, still as Figure 8 shown, after the third moment t3 and before the fourth moment t4, the controller 400 controls the compensation torque output by the drive motor to decrease to zero.

[0096] In the embodiment of the present application, before the brake pedal travel decreases to zero, the controller 400 actively reduces the compensation torque output by the drive motor 120 to zero first, which can make full use of the braking force output by the wheel-end braking device 210 in the braking system 200 to brake the electric vehicle 10, thereby reducing the braking distance of the electric vehicle 10.

[0097] In one embodiment, the controller 400 can also control the compensation torque output by the drive motor 120 to decrease to zero before the vehicle speed of the electric vehicle 10 decreases to zero.

[0098] Still as Figure 8 shown, at the fourth moment t4, the compensation torque output by the drive motor 120 decreases to zero, and the brake pedal travel decreases to zero. However, the vehicle speed of the electric vehicle 10 is not zero. At this time, the controller 400 can actively control the braking force output by the wheel-end braking device 210 in the braking system 200 to gradually decrease from a small value to zero. Based on this, when the vehicle speed of the electric vehicle 10 is small (for example, 3 km / h), the electric vehicle 10 can be gradually decelerated to a stop by the braking force output by the wheel-end braking device 210 and the road surface resistance, thereby improving the comfort of the braking process.

[0099] In the embodiment of the present application, before the vehicle speed of the electric vehicle 10 decreases to zero, the controller 400 actively reduces the compensation torque output by the drive motor 120 to zero first, which can avoid the driving force provided by the compensation torque from increasing the braking distance of the electric vehicle 10.

[0100] In one embodiment, when the vehicle speed of the electric vehicle 10 is small, the electric vehicle 10 can also be gradually decelerated to a stop only by the deceleration provided by the road surface resistance. Among them, because the road surface resistance is only affected by the weight of the electric vehicle 10 and the road surface friction coefficient. Therefore, the deceleration of the electric vehicle 10 remains basically unchanged.

[0101] In the embodiments of the present application, when the travel of the brake pedal decreases to zero and the vehicle speed is very low, the electric vehicle 10 can be decelerated to a stop by controlling the road surface resistance, which can further reduce the deceleration of the electric vehicle 10, thereby further improving the comfort of braking.

[0102] It should be understood that the method of decelerating the electric vehicle 10 to a stop by controlling the road surface resistance when the vehicle speed of the electric vehicle 10 is very low is only applicable to the case where the vehicle speed is very low and the road surface adhesion coefficient is relatively high. When the braking distance in front of the electric vehicle 10 is limited or the road surface adhesion coefficient is relatively low, when the travel of the brake pedal decreases to zero, the vehicle speed of the electric vehicle 10 should decrease to zero to improve the safety of braking while improving the comfort at the end of braking.

[0103] In one embodiment, after the third moment t3 and before the fourth moment t4, when the decreasing rate of the brake pedal travel is greater than the preset decreasing rate, the controller 400 controls the braking force output by the braking system 200 to the four wheels to decrease as the brake pedal travel decreases and controls the compensation torque output by the drive motor 120 to start decreasing.

[0104] The fact that the decreasing rate of the brake pedal travel is greater than the preset decreasing rate indicates that the driver quickly releases the brake pedal. At this time, the rapid decrease in the braking force output by the braking system 200 to the four wheels will cause the deceleration of the electric vehicle 10 to decrease too quickly, thereby causing the electric vehicle 10 to lunge forward. Based on this, the compensation torque output by the drive motor 120 needs to decrease quickly to keep the driving force and braking force of the electric vehicle 10 balanced, so as to control the electric vehicle 10 to decelerate smoothly to a stop.

[0105] In one embodiment, still as Figure 8 shown, after the third moment t3 and before the fourth moment t4, the controller 400 controls the compensation torque output by the drive motor 120 to decrease as the brake pedal travel decreases.

[0106] The decrease in the brake pedal travel after the third moment t3 and before the fourth moment t4 indicates that the braking force of the braking system 200 braking the four wheels decreases. At this time, the compensation torque output by the drive motor 120 decreases accordingly, which can make the deceleration provided by the electric vehicle 10 decrease smoothly, so that the electric vehicle 10 can continue to be braked comfortably when the brake pedal travel decreases.

[0107] In one embodiment, during the process that the controller 400 controls the compensation torque output by the drive motor 120 to decrease as the brake pedal travel decreases, the greater the decreasing rate of the brake pedal travel, the greater the decreasing rate of the compensation torque output by the controller 400 to control the drive motor 120.

[0108] During the braking process of the electric vehicle 10, the greater the rate of decrease in the braking pedal travel indicates that the driver releases the braking pedal faster. At this time, keeping the rate of decrease in the compensation torque unchanged will cause the driving force provided by the drive motor 120 to be too large, resulting in too fast a lateral deceleration of the electric vehicle 10 and causing the electric vehicle 10 to lurch forward.

[0109] In an embodiment of the present application, the greater the rate of decrease in the braking pedal travel, the greater the rate of decrease in the compensation torque output by the controller 400 to control the drive motor 120. Based on this, when the braking pedal travel decreases, the braking force provided by the wheel-end braking device 210 of the electric vehicle 10 and the driving force provided by the drive motor 120 can be kept balanced, so as to more smoothly control the electric vehicle 10 to decelerate to a stop.

[0110] In one embodiment, after the second moment t2 and before the third moment t3, the controller 400 can control the compensation torque output by the drive motor 120 to change with the deceleration of the electric vehicle. For example, still as Figure 8 shown, the controller 400 controls the compensation torque output by the drive motor 120 to decrease as the deceleration of the electric vehicle 10 decreases.

[0111] Based on this, adjusting the compensation torque output by the drive motor 120 according to the deceleration of the electric vehicle 10 can more accurately control the deceleration of the electric vehicle 10, so that the electric vehicle 10 decelerates to a stop more smoothly.

[0112] It should be understood that when the deceleration of the electric vehicle 10 increases, the controller 400 can also control the compensation torque output by the drive motor 120 to increase as the deceleration of the electric vehicle increases. This is not elaborated in the embodiments of the present application.

[0113] In one embodiment, after the second moment t2 and before the third moment t3, the controller 400 can control the compensation torque output by the drive motor 120 according to the deceleration of the electric vehicle 10 indicated by the resolver sensor. Since the resolver sensor can detect the rotational speed of the wheel more quickly and accurately, the controller 400 can quickly and accurately calculate the deceleration of the electric vehicle 10 based on the rotational speed detected by the resolver sensor, thereby reducing the time delay of the entire control process.

[0114] In one embodiment, after the second moment t2 and before the third moment t3, when the difference between the deceleration of the electric vehicle 10 indicated by the resolver sensor of the drive motor 120 and the deceleration of the electric vehicle 10 indicated by the acceleration sensor is greater than a preset difference, the compensation torque output by the drive motor 120 is controlled according to the deceleration of the electric vehicle 10 indicated by the acceleration sensor.

[0115] In the embodiment of the present application, the difference between the deceleration of the electric vehicle 10 indicated by the resolver sensor and the deceleration of the electric vehicle 10 indicated by the acceleration sensor is greater than the preset difference, indicating that the wheel corresponding to the drive motor 120 is slipping. At this time, the deceleration calculated based on the rotation speed detected by the resolver sensor cannot accurately represent the deceleration of the electric vehicle 10, resulting in the inability to continue to control the electric vehicle 10 to perform comfort braking. At this time, the compensation torque output by the drive motor 120 controlled by the deceleration of the electric vehicle 10 indicated by the acceleration sensor can continue to perform comfort braking on the electric vehicle 10, thereby expanding the applicable scenarios of comfort braking.

[0116] When the slope of the road changes during the comfort braking of the electric vehicle 10, the resistance encountered by the electric vehicle 10 will also change. When the resistance encountered by the electric vehicle 10 changes, the drive motor 120 may cause the electric vehicle 10 to decelerate to zero too quickly or fail to stop in time if the compensation torque output by the drive motor 120 remains unchanged. For example, during the uphill driving of the electric vehicle 10, the weight of the electric vehicle 10 itself will provide the electric vehicle 10 with a gravity component opposite to the driving direction, thereby increasing the resistance of the electric vehicle 10. Among them, the greater the slope of the road, the greater the resistance generated by the load of the electric vehicle 10 itself. Correspondingly, the greater the resistance generated by the load of the electric vehicle 10 itself, the greater the deceleration of the electric vehicle 10, causing the electric vehicle 10 to stop too quickly and cause a setback.

[0117] In one embodiment, between the second moment t2 and the third moment t3, when the resistance of the electric vehicle 10 increases and the increase rate of the deceleration of the electric vehicle 10 is greater than the preset increase rate, the controller 400 controls the compensation torque output by the drive motor 120 to increase.

[0118] Figure 10 Another schematic diagram of a control process of a non-sensing brake of an electric vehicle provided in an embodiment of the present application. Figure 10 As shown, at time t21 between the second time t2 and the third time t3, the electric vehicle 10 changes from flat road driving to uphill driving, so that the increase rate of the deceleration of the electric vehicle 10 is greater than the preset increase rate (for example, the preset increase rate is 0.5 m / S 2 ), the controller 400 controls the compensation torque output by the drive motor 120 to increase. The increase value of the compensation torque is positively correlated with the weight of the electric vehicle 10 and the slope of the road surface.

[0119] In the embodiment of the present application, when the resistance of the electric vehicle 10 increases during the comfort braking process, the controller can actively increase the compensation torque output by the drive motor 120, thereby reducing the deceleration of the electric vehicle 10, and preventing the electric vehicle 10 from stopping too quickly due to the increase in resistance of the electric vehicle 10, causing the vehicle to stall. In addition, increasing the compensation torque output by the drive motor 120 can also offset the influence of the gravity of the electric vehicle 10 during the uphill process, and prevent the electric vehicle 10 from sliding down the slope.

[0120] In one embodiment, after the deceleration of the electric vehicle 10 increases to the maximum after the time t21 and before the third time t3, the brake pedal travel decreases, and the controller 400 controls the compensation torque output by the drive motor 120 to decrease. Figure 10 As shown, after time t22, the controller 400 can refer to Figure 8 The corresponding technical principle in the embodiment of the present application is used to control the compensation torque output by the drive motor 120, which will not be described in detail here.

[0121] When the electric vehicle 10 is traveling downhill, the weight of the electric vehicle 10 itself will provide the electric vehicle 10 with a gravity component in the same direction of travel, thereby increasing the acceleration of the electric vehicle 10 and reducing the deceleration of the electric vehicle 10, causing the electric vehicle 10 to be unable to stop in time.

[0122] In one embodiment, between the second moment t2 and the third moment t3, when the resistance of the electric vehicle 10 decreases and the reduction rate of the deceleration of the electric vehicle 10 is greater than the preset reduction rate, the controller 400 controls the compensation torque output by the drive motor 120 to decrease at a rate greater than the preset reduction rate.

[0123] Figure 11 Another schematic diagram of a control process of a non-sensing brake of an electric vehicle provided in an embodiment of the present application. Figure 11 As shown, at time t21 between the second time t2 and the third time t3, the electric vehicle 10 changes from driving on a flat road to driving downhill, so that the reduction rate of the deceleration of the electric vehicle 10 is greater than the preset reduction rate (i.e., the slope of the preset deceleration corresponding to the dotted line after time t21), and the controller 400 controls the compensation torque output by the drive motor 120 to decrease. The reduction value of the compensation torque is positively correlated with the weight of the electric vehicle 10 and the slope of the road surface.

[0124] In an embodiment of the present application, when the resistance encountered by the electric vehicle 10 is reduced during comfort braking, the controller 400 can actively reduce the compensating torque output by the drive motor 120, thereby increasing the deceleration of the electric vehicle 10 and avoiding the electric vehicle 10 being unable to stop in time due to the reduction in resistance of the electric vehicle 10.

[0125] In one embodiment, after time t21 and before the third time t3, the rate of decrease of the deceleration of the electric vehicle 10 is less than or equal to the preset rate of decrease, the brake pedal stroke decreases, and the controller 400 controls the compensation torque output by the drive motor 120 to decrease. Figure 11 As shown, after time t22, the controller 400 can refer to Figure 8 The corresponding technical principle in the embodiment of the present application is used to control the compensation torque output by the drive motor 120, which will not be described in detail here.

[0126] In one embodiment, when the electric vehicle 10 is driving on a bumpy road or other road conditions that may cause the resistance of the electric vehicle 10 to change during the comfort braking process, the compensation torque output by the drive motor 120 may also refer to Figure 10 and Figure 11 The technical principle is to adjust in real time according to the change of the resistance of the electric vehicle 10, so as to ensure that the electric vehicle 10 can still achieve comfortable braking when driving on bumpy roads. In addition, when the resistance of the electric vehicle 10 changes after time t22, it can also refer to Figure 10 or Figure 11 The technical principle of the drive motor 120 is used to adjust the output compensation torque, which will not be described in detail in the embodiment of the present application.

[0127] During the comfort braking of the electric vehicle 10, the brake pedal travel reduction rate may change when the driver releases the brake pedal. When the brake pedal travel reduction rate changes, the compensation torque output by the drive motor 120 remains unchanged, which may still cause the deceleration of the electric vehicle 10 to decrease too quickly, causing the electric vehicle 10 to rush forward.

[0128] In one embodiment, between the second time t2 and the third time t3, the brake pedal stroke decreases at a first stroke reduction rate, and the compensating torque output by the control drive motor 120 decreases at a first rate. The brake pedal stroke decreases at a second stroke reduction rate greater than the first stroke reduction rate, and the compensating torque output by the control drive motor 120 decreases at a second rate greater than the first rate.

[0129] Figure 12 Another schematic diagram of a control process of a non-sensing brake of an electric vehicle provided in an embodiment of the present application. Figure 12As shown, at time t5 between the second time t2 and the third time t3, the brake pedal stroke decreases at a first stroke decreasing rate, and the compensation torque output by the control drive motor 120 decreases at a first rate. At time t6 between time t5 and the third time t3, the brake pedal stroke decreases at a second stroke decreasing rate, and the compensation torque output by the control drive motor 120 decreases at a second rate greater than the first rate. After time t6, the compensation torque output by the control drive motor 120 gradually decreases to zero as the brake pedal stroke decreases. Among them, the greater the slope between the brake pedal stroke reduction process and the time axis, the greater the brake pedal stroke reduction rate.

[0130] In the embodiment of the present application, between the second time t2 and the third time t3, the controller 400 actively adjusts the reduction rate of the compensation torque output by the drive motor 120 according to the reduction rate of the brake pedal stroke, so that the braking force output by the braking device and the deceleration provided by the compensation torque output by the drive motor 120 for the electric vehicle 10 can be stably reduced, avoiding the electric vehicle 10 from surging forward.

[0131] During the comfort braking process of the electric vehicle 10, when the gear of the electric vehicle 10 changes, the compensation torque output by the drive motor 120 will also impact the electric vehicle 10, affecting the riding experience.

[0132] In one embodiment, after the second time t2, when the gear of the electric vehicle 10 is switched from the forward gear to the reverse gear or the parking gear, the controller 400 controls the compensation torque output by the drive motor 120 to decrease.

[0133] When the gear of the electric vehicle 10 is switched from the forward gear to the reverse gear or the parking gear, if the compensation torque output by the drive motor 120 remains unchanged, the electric vehicle 10 will continue to move forward, resulting in the electric vehicle 10 being unable to respond to the operation after shifting gears in a timely manner.

[0134] In the embodiment of the present application, after the gear of the electric vehicle 10 is switched from the forward gear to the reverse gear or the parking gear, the controller 400 actively controls the reduction of the compensation torque output by the drive motor, which can brake the vehicle in time, so that the electric vehicle 10 can respond to the operation after shifting gears more timely.

[0135] In the above implementation process, when the gear of the electric vehicle 10 changes during the comfort braking process of the electric vehicle 10, the controller 400 can actively increase the reduction rate of the compensation torque output by the drive motor 120, so that the driving force provided by the compensation torque output by the drive motor 120 for the electric vehicle 10 decreases faster, avoiding the compensation torque output by the drive motor 120 after the gear shift of the electric vehicle 10 from affecting the electric vehicle 10 to perform subsequent operations.

[0136] During the braking process of the electric vehicle 10, the controller 400 controls the four wheel-end braking devices 210 of the braking system 200 to brake the four wheels of the electric vehicle 10 respectively. Among them, the controller 400 distributes the braking forces of the four wheels to enable the electric vehicle 10 to brake more smoothly during the braking process. For example, when braking while the electric vehicle 10 is moving forward, since the center of gravity of the electric vehicle 10 will shift forward, the braking forces of the two front wheels are greater than those of the two rear wheels, preventing the two front wheels from slipping.

[0137] During the braking process of the electric vehicle 10, when the braking forces of the two front wheels are greater than those of the two rear wheels and both the two front wheels and the two rear wheels of the electric vehicle 10 are driven by the drive motors 120, the same front-wheel compensation torque output by the front-wheel drive motors corresponding to the two front wheels and the rear-wheel compensation torque output by the rear-wheel drive motors corresponding to the two rear wheels will cause the deceleration of the two front wheels to be greater than that of the two rear wheels, resulting in vehicle body jerks.

[0138] In one embodiment, in order to further improve the driving and riding experience during comfortable braking of the electric vehicle 10, after the second moment t2 and before the third moment t3, when the braking forces of the braking system 200 on the two front wheels are greater than those on the two rear wheels, the controller 400 actively controls the front-wheel compensation torque output by the front-wheel drive motors corresponding to the two front wheels of the electric vehicle 10 to be greater than the rear-wheel compensation torque output by the rear-wheel drive motors corresponding to the two rear wheels.

[0139] Figure 13 Another schematic diagram of the control process for the electric vehicle to achieve seamless braking provided by the embodiments of the present application. As Figure 13 shown, when braking during the forward movement of the electric vehicle 10, after the second moment t2 and before the third moment t3, the braking force F1 of the left front wheel FL and the braking force F2 of the right front wheel FR are greater than the braking force F3 of the left rear wheel RL and the braking force F4 of the right rear wheel.

[0140] In one embodiment, after the second moment t2 and before the third moment t3, the compensation torque T1 output by the drive motor 120 of the left front wheel FL and the compensation torque T2 output by the drive motor 120 of the right front wheel FR are greater than the compensation torque T3 output by the drive motor 120 of the left rear wheel RL and the compensation torque T4 output by the drive motor 120 of the right rear wheel RR. Among them, the left front wheel FL and the right front wheel FR are driven by one drive motor 120, and the left rear wheel RL and the right rear wheel RR are driven by another drive motor 120. Alternatively, the left front wheel FL, the right front wheel FR, the left rear wheel RL, and the right rear wheel RR are each driven by one drive motor 120.

[0141] Based on this, when braking during the forward movement of the electric vehicle 10, the controller 400 can control the deceleration of the two front wheels and the two rear wheels to be basically the same, so as to perform a comfortable braking on the electric vehicle 10 more smoothly.

[0142] In one embodiment, after the third moment t3 and before the fourth moment t4, when the braking pedal travel of the electric vehicle 10 decreases, the controller 400 controls the front-wheel compensation torque output by the front-wheel drive motor and the rear-wheel compensation torque output by the rear-wheel drive motor to decrease, and the front-wheel compensation torque output by the front-wheel drive motor is always greater than the rear-wheel compensation torque output by the rear-wheel drive motor.

[0143] In one embodiment, after the third moment t3 and before the fourth moment t4, the controller 400 controls the compensation torque T1 output by the drive motor 120 corresponding to the left front wheel FL, the compensation torque T2 output by the drive motor 120 corresponding to the right front wheel FR, the compensation torque T3 output by the drive motor 120 corresponding to the left rear wheel RL, and the compensation torque T4 output by the drive motor 120 corresponding to the right rear wheel RR to decrease.

[0144] In the embodiment of the present application, when the braking pedal travel of the electric vehicle 10 decreases, the controller 400 actively controls the front-wheel compensation torque output by the front-wheel drive motor and the compensation torque output by the rear-wheel drive motor to decrease, which can increase the deceleration of the electric vehicle 10, so as to ensure that the electric vehicle 10 stops more quickly during the execution of comfortable braking and improve the safety during comfortable braking.

[0145] When performing comfortable braking during the process of the decrease of the braking pedal travel of the electric vehicle 10 and the distance between the electric vehicle 10 and the obstacle is small, the slower decrease of the deceleration of the electric vehicle 10 will increase the braking distance of the electric vehicle 10, posing a safety hazard.

[0146] In one embodiment, after the third moment t3 and before the fourth moment t4, the controller 400 controls the front-wheel drive motor to reduce the output front-wheel compensation torque while controlling the rear-wheel drive motor to reduce the output rear-wheel compensation torque.

[0147] Still as Figure 13 shown, after the third moment t3 and before the fourth moment t4, the controller 400 controls the compensation torque T1 output by the drive motor 120 corresponding to the left front wheel FL, the compensation torque T2 output by the drive motor 120 corresponding to the right front wheel FR, the compensation torque T3 output by the drive motor 120 corresponding to the left rear wheel RL, and the compensation torque T4 output by the drive motor 120 corresponding to the right rear wheel RR to synchronously decrease to zero.

[0148] In the embodiment of the present application, by first simultaneously controlling the compensation torque of the wheel to decrease to zero and then controlling the rotational speed of the wheel to decrease to zero, the braking distance of the electric vehicle 10 can be reduced, thereby improving the safety during the comfort braking process.

[0149] During the braking process of the electric vehicle 10, when the wheels of the electric vehicle 10 slip, if the compensation torque of the slipping wheel is too large, it will increase the slipping tendency of the electric vehicle 10.

[0150] In one embodiment, after the third moment t3 and before the fourth moment t4, if the rotational speed of the left front wheel of the electric vehicle 10 is greater than the preset rotational speed, indicating that the left front wheel slips, the controller 400 can actively control the compensation torque T1 output by the drive motor 120 corresponding to the left front wheel FL to be less than the compensation torque T2 output by the drive motor 120 corresponding to the right front wheel FR. Based on this, the controller can ensure that the electric vehicle 10 can still perform comfortable braking relatively smoothly when the wheels slip by actively reducing the compensation torque of the slipping wheel.

[0151] In one embodiment, when the distance between the electric vehicle 10 and the obstacle is relatively large during the comfort braking process of the electric vehicle 10, after the third moment t3 and before the fourth moment t4, the controller 400 can first control the front drive motor to reduce the output front drive compensation torque. Then, the controller controls the rear drive motor to reduce the output rear drive compensation torque.

[0152] In the embodiment of the present application, the controller can more gently reduce the deceleration of the electric vehicle 10 by actively controlling the front drive motor to first reduce the output front drive compensation torque and then controlling the rear drive motor to reduce the output rear drive compensation torque, further improving the comfort during the comfort braking process.

[0153] It should be understood that when the compensation torque output by the drive motor 120 decreases as the braking pedal stroke decreases after the third moment t3 and before the fourth moment t4, the controller 400 can also first control the rear drive motor to reduce the output rear drive compensation torque. Then, it controls the front drive motor to reduce the output front drive compensation torque.

[0154] Based on the same technical principle, when the electric vehicle 10 brakes while moving backward, since the center of gravity of the electric vehicle 10 will shift backward, the braking force of the two rear wheels is greater than that of the two front wheels. At this time, during the comfort braking process, the controller controls the compensation torque T1 of the left front wheel FL and the compensation torque T2 of the right front wheel FR to be less than the compensation torque T3 of the left rear wheel RL and the compensation torque T4 of the right rear wheel RR. In addition, the controller 400 can also reduce the compensation torque output by the drive motor 120 with reference to the Figure 13 method, which will not be elaborated in this embodiment of the present application.

[0155] When the electric vehicle 10 is in a turning state during braking, the braking force of the wheel on the turning side is greater than the braking force of the vehicle on the other side. When the electric vehicle 10 is comfortably braked under this condition, the compensation torque output by the drive motor 120 to the wheel on the turning side is greater than the compensation torque on the other side, which may cause the electric vehicle 10 to understeer.

[0156] In one embodiment, when each of the four wheels of the electric vehicle 10 is driven by a drive motor 120, after the third moment t3 and before the fourth moment t4, the steering angle of the steering wheel of the electric vehicle 10 turning left is greater than the preset angle, and the controller 400 can also control the compensation torque output by the drive motor 120 on the right side of the electric vehicle 10 to be greater than the compensation torque output by the drive motor 120 on the left side. That is, the compensation torque T2 of the right front wheel FR is controlled to be greater than the compensation torque T1 of the left front wheel FL, and the compensation torque T3 of the right rear wheel RR is controlled to be greater than the compensation torque T4 of the left rear wheel RL. Based on this, the controller 400 can actively adjust the compensation torque of the vehicles on both sides during the steering process of the electric vehicle 10 to perform comfortable braking on the electric vehicle 10.

[0157] It should be understood that when the electric vehicle 10 turns right, the compensation torque output by the drive motor 120 corresponding to the left wheel can be controlled to be greater than or equal to the compensation torque output by the drive motor 120 corresponding to the right wheel based on the above technical principles.

[0158] In summary, the embodiments of the present application provide a control method, a controller and an electric vehicle for a senseless braking of an electric vehicle. The control method can actively reduce the compensating torque output by the drive motor 120 when the brake pedal travel is reduced during the comfortable braking of the electric vehicle, thereby preventing the electric vehicle from rushing forward, thereby further improving the comfort of the electric vehicle during the comfortable braking process.

[0159] 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 control method for electric vehicle non-sensing braking, characterized in that: The control method is used to control the drive motor to output a compensation torque during the braking process of the electric vehicle to reduce the setback of the electric vehicle during the braking process, and the control method includes: After a first moment when the brake pedal stroke increases from zero and before a second moment when the brake system brakes to a speed of the electric vehicle equal to a preset speed, controlling the brake system to continuously brake the four wheels of the electric vehicle and controlling the torque output by the drive motor to be zero; After the second moment and before a third moment when the brake pedal stroke is reduced to be equal to the preset stroke, controlling the brake system to continue braking the four wheels and controlling the drive motor to output a compensation torque in the same direction as the rotation speed of the four wheels; After the third moment and before the fourth moment when the brake pedal stroke is reduced to zero, the braking force output by the braking system to the four wheels is controlled to decrease as the brake pedal stroke decreases and the compensation torque output by the drive motor is controlled to start decreasing.

2. The control method according to claim 1, characterized in that: The control method further comprises: After the third moment and before the fourth moment, the compensation torque output by the driving motor is controlled to decrease to zero.

3. The control method according to claim 1, characterized in that: The control method further comprises: Before the vehicle speed of the electric vehicle decreases to zero, the compensation torque output by the driving motor is controlled to decrease to zero.

4. The control method according to claim 1, characterized in that: After the third moment and before the fourth moment, the brake pedal stroke reduction rate is greater than a preset reduction rate.

5. The control method according to any one of claims 1 to 4, characterized in that: The control method further comprises: After the third moment and before the fourth moment, the compensation torque output by the driving motor is controlled to decrease as the brake pedal stroke decreases.

6. The control method according to claim 5, characterized in that: The control method further comprises: In the process of controlling the compensating torque output by the drive motor to decrease as the brake pedal stroke decreases, the greater the brake pedal stroke reduction rate is, the greater the reduction rate of the compensating torque output by the drive motor is.

7. The control method according to claim 1, characterized in that: The control method further comprises: After the second moment, when the gear position of the electric vehicle is switched from a forward gear to a reverse gear or a parking gear, the compensation torque output by the driving motor is controlled to decrease.

8. The control method according to any one of claims 1 to 7, characterized in that: The control method further comprises: After the second moment and before the third moment, the compensation torque output by the driving motor is controlled to change with the change of the deceleration of the electric vehicle.

9. The control method according to claim 8, characterized in that: Controlling the compensation torque output by the drive motor to change with the change of the deceleration of the electric vehicle specifically includes: The compensating torque output by the driving motor is controlled to increase as the deceleration of the electric vehicle increases, and the compensating torque output by the driving motor is controlled to decrease as the deceleration of the electric vehicle decreases.

10. The control method according to claim 1, characterized in that: The control method further comprises: After the second moment and before the third moment, the difference between the deceleration of the electric vehicle indicated by the rotary sensor of the drive motor and the deceleration of the electric vehicle indicated by the acceleration sensor is greater than a preset difference, and the compensation torque output by the drive motor is controlled according to the deceleration of the electric vehicle indicated by the acceleration sensor.

11. The control method according to claim 1, characterized in that: The control method further comprises: After the second moment and before the third moment, when the braking force output by the braking system to the two front wheels is greater than the braking force output to the two rear wheels, the compensation torque output by the front drive motor is controlled to be greater than the compensation torque output by the rear drive motor.

12. The control method according to claim 1, characterized in that: The control method further comprises: After the third moment and before the fourth moment, the front drive motor is controlled to reduce the output front drive compensation torque, and the rear drive motor is controlled to reduce the output rear drive compensation torque.

13. The control method according to claim 1, characterized in that: The control method further comprises: After the third moment and before the fourth moment, the steering wheel of the electric vehicle turns left at a greater angle than a preset angle, and the compensation torque output by the drive motor on the left side of the electric vehicle is controlled to be smaller than the compensation torque output by the drive motor on the right side.

14. A controller for an electric vehicle, characterized in that: The controller is used to control the electric vehicle during the braking process of the electric vehicle to implement the control method described in any one of claims 1-13.

15. An electric vehicle, characterized in that: The electric vehicle uses the control method described in any one of claims 1 to 13 to control the drive motor of the electric vehicle to output a compensation torque during the braking process of the electric vehicle.

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