Braking method and system based on four-motor independent drive electric automobile and automobile

Abstract

The invention relates to the technical field of vehicle braking, in particular to a braking method and system based on an electric vehicle independently driven by four motors and the vehicle. The braking method comprises the steps that the total braking torque needed by the four driving motors is periodically obtained based on received braking intention signals; based on the total braking torque and the state information of the whole vehicle, the braking target torque of each driving motor is determined; and correcting the braking target torque of each driving motor at least based on the braking target torque of each driving motor, the corresponding maximum torque limit value, the rotating speed information and the actually output first braking torque, and controlling each driving motor to realize service braking. The driving braking is realized by controlling each driving motor, and a hydraulic braking system does not need to be configured for the automobile, so that the number of parts of the braking system is reduced, the cost and weight of the whole automobile are reduced, the energy consumption of the whole automobile is reduced, and the endurance of the whole automobile can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of vehicle braking technology, and in particular to a braking method, system and vehicle based on a four-motor independently driven electric vehicle. Background Art

[0002] In the prior art, the braking system of electric vehicles mostly uses a combination of hydraulic braking and motor braking to achieve braking.

[0003] However, for electric vehicles with four independent motors, many functions of hydraulic braking can be achieved by motor braking. If a separate hydraulic braking system is arranged, it will not only increase the cost of the whole vehicle, but also increase the weight of the whole vehicle, thereby increasing energy consumption. This is contrary to the vehicle manufacturers' pursuit of reducing vehicle costs and reducing vehicle energy consumption. Summary of the invention

[0004] Based on the above technical problems, the present disclosure provides a braking method, system and vehicle based on four-motor independently driven electric vehicle.

[0005] According to one aspect of the present disclosure, a braking method for an electric vehicle independently driven by four motors is provided, comprising: periodically obtaining the total braking torque required by the four drive motors based on a received braking intention signal; determining the braking target torque of each drive motor based on the total braking torque and status information of the entire vehicle; determining whether to correct the braking target torque of each drive motor based on the braking target torque of each drive motor and its corresponding maximum torque limit and speed information, and controlling each drive motor to achieve service braking.

[0006] In addition, according to one aspect of the present disclosure, a braking method for an electric vehicle independently driven by four motors periodically obtains the total braking torque required by the four drive motors based on a received braking intention signal, including: periodically obtaining pedal opening information based on the received braking intention signal; and obtaining the total braking torque required by the four drive motors based on the pedal opening information.

[0007] In addition, according to an aspect of the present disclosure, in a braking method for an electric vehicle independently driven by four motors, the status information of the whole vehicle includes the load information of the whole vehicle; based on the total braking torque and the status information of the whole vehicle, the braking target torque of each drive motor is determined, including: based on the load information of the whole vehicle, the front axle load and the rear axle load of the whole vehicle are determined; based on the total braking torque, the front axle load and the rear axle load, the braking target torque of each drive motor is determined.

[0008] In addition, according to an aspect of the present disclosure, in a braking method for an electric vehicle independently driven by four motors, the braking target torque of each drive motor is corrected, including a first correction operation and a second correction operation; the first correction operation is: if the braking target torque of at least one drive motor is greater than its corresponding maximum torque limit, the braking target torque of at least one drive motor is replaced by the maximum torque limit; or, if the braking target torque of each drive motor is not greater than its corresponding maximum torque limit, the braking target torque of each drive motor is not corrected; the second correction operation is: if, based on the speed information of each drive motor, it is determined that the wheel corresponding to at least one drive motor is in a slipping state, based on the first braking torque actually outputted by the at least one drive motor and the anti-skid correction coefficient, the braking target torque of the at least one drive motor is adjusted; or, if, based on the speed information of each drive motor, it is determined that the wheels corresponding to each drive motor are not in a slipping state, the braking target torque of each drive motor is not adjusted.

[0009] In addition, according to one aspect of the present disclosure, a braking method for an electric vehicle based on four independent motors, the method also includes: when performing a first correction operation and a second correction operation on the braking target torque of each driving motor, ensuring that the braking target torque of each driving motor is not greater than its corresponding maximum torque limit.

[0010] In addition, according to an aspect of the present disclosure, a braking method for an electric vehicle based on four independent motor drives, the method also includes: when the whole vehicle is parked, based on the left rear brake and the right rear brake, the whole vehicle is kept stationary.

[0011] According to another aspect of the present disclosure, a braking system for a four-motor independently driven electric vehicle is provided, characterized in that it includes a first controller module, which is used to: periodically obtain the total braking torque required by the four drive motors based on the received braking intention signal; determine the braking target torque of each drive motor based on the total braking torque and the status information of the whole vehicle; determine whether to correct the braking target torque of each drive motor based on at least the braking target torque of each drive motor, its corresponding maximum torque limit, speed information and the first braking torque actually output, and control each drive motor to achieve service braking.

[0012] In addition, according to another aspect of the present disclosure, the braking system for a four-motor independently driven electric vehicle further includes: a second controller module, which is used to keep the entire vehicle stationary based on the left rear brake and the right rear brake when the entire vehicle is parked.

[0013] According to another aspect of the present disclosure, a four-motor independently driven electric vehicle is provided, and the four-motor independently driven electric vehicle is braked using the above-mentioned braking method based on the four-motor independently driven electric vehicle.

[0014] In addition, according to another aspect of the present disclosure, the four-motor independent drive electric vehicle has only a left rear brake and a right rear brake.

[0015] The braking method, system and vehicle based on four-motor independently driven electric vehicle provided by the present disclosure obtain the required total braking torque of the four drive motors by periodically receiving braking intention signals, and correct the second braking target torque of each drive motor according to the total braking torque, the maximum torque limit of each drive motor and the speed information, so as to realize driving braking by controlling the drive motors. Vehicle braking can be realized without configuring a hydraulic braking system for the vehicle, which not only reduces the number of braking system components, reduces the cost and weight of the whole vehicle, reduces the energy consumption of the whole vehicle, but also improves the cruising range of the whole vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present disclosure or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 1 is a flow chart illustrating a braking method based on a four-motor independently driven electric vehicle according to an embodiment of the present disclosure.

[0018] Figure 2 is a functional block diagram illustrating a braking system for a four-motor independently driven electric car wash according to an embodiment of the present disclosure.

[0019] Figure 3 is a functional block diagram further illustrating a braking system for a four-motor independently driven electric car wash according to an embodiment of the present disclosure.

[0020] Figure 4 is a schematic diagram illustrating a four-motor independently driven electric vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the technical solutions in the present disclosure will be clearly and completely described below in conjunction with the drawings in the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0022] At present, the braking system of electric vehicles generally adopts a combination of hydraulic braking and motor braking. There are two main ways to implement hydraulic braking. One of them is to combine a vacuum booster, a vacuum pump and a hydraulic braking system. This method not only has a poor driving experience, but also most of the braking energy is wasted by the brakes converted into heat energy; the other is to integrate the intelligent braking system iBooste with the hydraulic braking system. This method can achieve better braking energy recovery and help reduce the energy consumption of the whole vehicle. However, for electric vehicles with four independent motors, many functions of hydraulic braking can actually be replaced by motor braking. If a set of hydraulic braking systems is still configured independently, this will cause the functions of hydraulic braking and motor braking to overlap, resulting in redundancy of brake components such as brakes, wheel speed sensors, ESC actuators, iBooste, etc., which will not only increase the manufacturing cost of the whole vehicle, but also increase the weight of the whole vehicle, thereby increasing energy consumption. This runs counter to the current goal of vehicle manufacturers to reduce vehicle costs and energy consumption.

[0023] Based on the above technical problems, the present disclosure provides a braking method for an electric vehicle based on four independent motor drives.

[0024] Figure 1 1 is a flow chart illustrating a braking method based on a four-motor independently driven electric vehicle according to an embodiment of the present disclosure.

[0025] like Figure 1 As shown, according to the braking method of the electric vehicle based on four independent motor drives according to the embodiment of the present disclosure, the method specifically includes the following steps.

[0026] Step S101 , periodically obtaining the total braking torque required by four driving motors based on the received braking intention signal.

[0027] In one embodiment of the present disclosure, the braking intention signal is key information for identifying the driver's braking intention, which mainly comes from the driver's operating behavior and the state monitoring of the vehicle. These signals include but are not limited to the displacement and displacement change rate of the brake pedal, the release speed and displacement change of the accelerator pedal, the vehicle speed and gear information, and the vehicle dynamic response such as deceleration and wheel speed information. The total braking torque refers to the torque required for the vehicle to achieve driving braking by controlling the four drive motors during the driving braking process. By continuously monitoring the braking intention signal, the braking intention signal can be analyzed to determine the size of the braking force desired by the driver, and the total braking target torque required by the four drive motors can be specifically calculated based on this. For example, the driver expresses the braking intention by stepping on the brake pedal, and the displacement and displacement change rate of the brake pedal can be captured by the sensor and converted into an electrical signal. The size of the braking force desired by the driver can be determined by analyzing the electrical signal, and the total braking target torque can be calculated based on this.

[0028] Step S102: determining the braking target torque of each driving motor based on the total braking torque and the state information of the entire vehicle.

[0029] In one embodiment of the present disclosure, the vehicle state includes but is not limited to the vehicle's mass distribution, driving speed, wheel grip (e.g., affected by road conditions, tire conditions, etc.), and the vehicle's dynamic response. The braking target torque refers to the braking torque that the drive motor is expected to output in response to the received braking intention signal. After determining the total braking target torque, the total braking target torque and the adjustment of the vehicle's state information can be used to calculate the braking target torque of each drive motor.

[0030] Step S103, at least based on the braking target torque of each driving motor, its corresponding maximum torque limit, the speed information and the actually output first braking torque, the braking target torque of each driving motor is corrected, and each driving motor is controlled to achieve service braking.

[0031] In one embodiment of the present disclosure, the maximum torque limit refers to the maximum braking torque that the drive motor can provide without being damaged or overheated. The first braking torque actually output is the braking torque actually generated by the motor. During the braking process, the braking target torque, maximum torque limit, speed information and the first braking torque actually output of each motor are monitored in real time, and the braking target torque of each drive motor is adjusted according to the braking target torque of each motor and its corresponding maximum torque limit, speed information and the first braking torque actually output, so as to control each drive motor to work with its corresponding braking target torque as the target, and realize driving braking by controlling each drive motor.

[0032] In one embodiment of the present disclosure, after the above step S103 is completed, the braking of the entire vehicle will be subjected to the next round of braking control, that is, starting from step S101 again, to ensure the continuity and adaptability of the entire braking process.

[0033] In one embodiment of the present disclosure, the motor controller of each drive motor sends the collected maximum torque limit, speed information and the first braking torque data actually outputted by each drive motor to the main motor controller MCU1 (i.e., the main motor controller among the four drive motors) in real time through the vehicle controller area network (CAN) network. This communication method ensures the real-time and reliability of the data, which is essential for achieving precise vehicle control. Similarly, when adjusting the braking target torque of each drive motor, the main motor controller will also send the corrected braking target torque of the drive motor to the corresponding motor controller of each drive motor through the vehicle CAN network. Here, the motor controller of each drive motor respectively controls the corresponding drive motor to work with its own drive motor braking target torque as the target, and transmits the braking recovery energy to the battery module of the vehicle, and the battery module is charged during the process.

[0034] In summary, according to the technical solution provided in the embodiment of the present disclosure, the present disclosure obtains the required total braking torque of the four drive motors by periodically receiving the braking intention signal, and corrects the second braking target torque of each drive motor according to the total braking torque, the maximum torque limit of each drive motor and the speed information, and then realizes the driving braking by controlling the drive motor. There is no need to configure a hydraulic braking system for the car to achieve vehicle braking, which not only reduces the number of braking system components, reduces the cost and weight of the whole vehicle, and reduces the energy consumption of the whole vehicle, but also improves the vehicle's endurance.

[0035] Furthermore, the total braking torque required by the four drive motors is periodically obtained based on the received braking intention signal, including: periodically obtaining pedal opening information based on the received braking intention signal; and obtaining the total braking torque required by the four drive motors based on the pedal opening information.

[0036] Specifically, during driving, when the driver steps on the brake pedal, a brake pedal electrical signal is generated, which is the braking intention signal. When the brake pedal electrical signal is received, the pedal opening information can be obtained by analyzing the brake pedal electrical signal, and the total braking target torque required to control the four drive motors to perform driving braking can be calculated based on the pedal opening information.

[0037] In one embodiment of the present disclosure, the pedal opening information includes the pedal opening and the rate of change of the pedal opening. The pedal opening refers to the position of the brake pedal relative to its completely unpressed (or completely released) state. Typically, the pedal opening is measured in percentages, where 0% means that the brake pedal is not pressed at all and 100% means that the brake pedal is fully pressed. The rate of change of the pedal opening refers to the speed at which the brake pedal opening changes over time. It indicates how quickly the driver presses or releases the brake pedal. The rate of change can be positive (indicating that the brake pedal is being pressed) or negative (indicating that the brake pedal is being released), and its magnitude (absolute value) indicates how fast the change is. By combining both the pedal opening and the rate of change of the pedal opening, the total braking target torque required for the four drive motors of the vehicle can be calculated.

[0038] In summary, according to the technical solution provided by the embodiment of the present disclosure, the driver's braking intention, including the pedal opening and the rate of change, is accurately captured to achieve dynamic adjustment of the braking torque, thereby improving the braking performance and safety of the four-motor independently driven electric vehicle and optimizing energy utilization efficiency.

[0039] Furthermore, the status information of the whole vehicle includes the load information of the whole vehicle; based on the total braking torque and the status information of the whole vehicle, the braking target torque of each drive motor is determined, including: based on the load information of the whole vehicle, the front axle load and the rear axle load of the whole vehicle are determined; based on the total braking torque, the front axle load and the rear axle load, the braking target torque of each drive motor is determined.

[0040] Specifically, the load information refers to the weight distribution currently carried by the vehicle. The front axle load refers to the weight borne by the front axle of the vehicle, and the rear axle load refers to the weight borne by the rear axle of the vehicle. By obtaining the load information of the vehicle, the front axle load and the rear axle load of the vehicle can be obtained through measurement or calculation. The braking target torque assigned to each drive motor can be calculated using the total braking target torque, the front axle load and the rear axle load. Exemplarily, by obtaining the load information of the vehicle, the front axle load and the rear axle load can be determined, and then the total braking target torque is distributed according to the ratio of the front axle load and the rear axle load, and the drive motors corresponding to the left and right wheels of the front and rear axles are initially distributed evenly, and a second braking target torque is allocated to each drive motor.

[0041] In summary, according to the technical solution provided in the embodiment of the present disclosure, the present disclosure can ensure that the braking force on each axle matches the weight it bears by distributing the braking torque according to the axle load ratio, thereby improving the stability of the vehicle during braking and achieving more precise and flexible braking control.

[0042] Furthermore, the braking target torque of each driving motor is corrected, including a first correction operation and a second correction operation.

[0043] The first correction operation is: if the braking target torque of at least one drive motor is greater than its corresponding maximum torque limit, the braking target torque of at least one drive motor is replaced by the maximum torque limit; or, if the braking target torque of each drive motor is not greater than its corresponding maximum torque limit, the braking target torque of each drive motor is not corrected.

[0044] The second correction operation is: if it is determined based on the speed information of each drive motor that the wheel corresponding to at least one drive motor is in a slipping state, the braking target torque of at least one drive motor is adjusted based on the first braking torque actually outputted corresponding to the at least one drive motor and the anti-skid correction coefficient; or, if it is determined based on the speed information of each drive motor that the wheels corresponding to each drive motor are not in a slipping state, the braking target torque of each drive motor is not adjusted.

[0045] Specifically, the braking target torque of each driving motor is corrected, including a first correction operation and a second correction operation.

[0046] The first correction operation refers to: checking the braking target torque of each drive motor to determine whether it exceeds the maximum torque limit of the drive motor. This is to ensure that the motor will not be damaged due to overload during braking. If it is found during the inspection that the braking target torque of at least one drive motor exceeds its maximum torque limit, the braking target torque of the drive motor will be corrected and set to the maximum torque limit. Exemplarily, if it is found during the inspection that the braking target torque of at least one drive motor exceeds its maximum torque limit, the braking target torque of the drive motor is modified to the maximum torque limit, and at the same time, the reduced automatic target torque of the drive motor is evenly distributed to other drive motors.

[0047] In one embodiment of the present disclosure, the first correction means that if the braking target torques of all drive motors do not exceed their respective maximum torque limits, then no correction is required to the braking target torques of these drive motors. In this case, the calculated braking target torques are considered safe and can be directly applied to each motor.

[0048] In one embodiment of the present disclosure, the second correction operation refers to: real-time monitoring of the speed information of each drive motor to determine whether the wheel corresponding to each drive motor is in a slipping state. Slipping is usually manifested as an increase in the difference between the wheel speed and the actual speed of the vehicle. If it is detected that the wheel corresponding to at least one drive motor is in a slipping state, the braking target torque of the drive motor will be adjusted to reduce or eliminate slipping. The adjustment can be based on the actual output first braking torque corresponding to the drive motor and the preset anti-skid correction coefficient to calculate a new, lower braking target torque to reduce the braking force on the slipping wheel, thereby helping the wheel regain grip. The preset anti-skid correction coefficient can be set according to actual application. The present disclosure is not limited here. For example, the preset anti-skid correction coefficient can be set to K, and K is 0.9-0.99, then the adjusted braking target torque of the drive motor is the product of the actual output first braking torque of the drive motor and the preset anti-skid correction coefficient K.

[0049] In one embodiment of the present disclosure, the second correction operation means that if it is detected that the wheels corresponding to all the drive motors are not in a slipping state, then there is no need to adjust the braking target torque of any drive motor. In this case, the current braking target torque is considered appropriate and can be maintained.

[0050] Further, when the first correction operation and the second correction operation are performed on the braking target torque of each driving motor, it is ensured that the braking target torque of each driving motor is not greater than the corresponding maximum torque limit value.

[0051] Specifically, during the first correction operation and the second correction operation of the braking target torque of each drive motor, it is ensured that the corrected braking target torque does not exceed the maximum torque limit of each motor. The "maximum torque limit" here refers to the maximum braking torque that the motor can provide without being damaged. The main purpose of the correction operation is to protect the drive motor from damage. The motor has its physical maximum torque bearing capacity, and exceeding this limit may cause the motor to overheat, damage or fail. By ensuring that the braking target torque does not exceed the maximum torque limit, it can ensure that the braking system operates within a safe range and avoid potential safety risks caused by overload. The first correction operation and the second correction operation are both performed dynamically. After each calculation of the braking target torque, it will be checked and necessary corrections will be made based on real-time data to adapt to changes in driving conditions and vehicle status. For the first correction operation: If the braking target torque of any drive motor exceeds its maximum torque limit, the braking target torque of this drive motor will be corrected to the maximum torque limit to ensure that it does not exceed the maximum bearing capacity of the motor. For the second correction operation: If the wheel corresponding to a certain drive motor is found to be slipping during monitoring, the braking target torque of the motor will be adjusted according to the actual output braking torque and the anti-skid correction coefficient, but the adjusted torque still cannot exceed the maximum torque limit. These two correction operations need to be considered comprehensively, not only to prevent motor overload, but also to deal with wheel slip. This means that while adjusting the braking torque to prevent slipping, it is also necessary to ensure that the adjusted value does not cause the motor to exceed its maximum torque limit. For example, if the braking target torque of a motor is corrected to the maximum torque limit in the first correction operation, and the reduced torque is evenly distributed to other motors, then when performing the second correction operation, it is necessary to check again whether the braking target torque of these motors exceeds their maximum torque limit.

[0052] This comprehensive correction strategy can provide effective braking force while ensuring the safety of the motor, thereby improving the braking performance and safety of electric vehicles. This method is particularly suitable for electric vehicles with four independent motors, because each motor can be controlled independently, thus achieving more precise and flexible braking control.

[0053] In summary, according to the technical solution provided by the embodiment of the present disclosure, the purpose of the first correction operation is to ensure that during the braking process, the braking target torque of each drive motor does not exceed its maximum physical bearing capacity, that is, the maximum torque limit. This correction operation is to protect the motor from damage while ensuring the effectiveness and safety of the braking system. The first correction operation is performed dynamically, and each time the braking target torque is calculated, an inspection and necessary correction will be performed to adapt to the real-time changing driving conditions and vehicle status. Through this first correction operation, it is possible to provide effective braking force while ensuring the safety of the drive motor, thereby improving the braking performance and safety of the electric vehicle. Further, the purpose of the second correction operation is to deal with the wheel slippage that may occur during the braking process. Slippage will reduce braking efficiency, increase braking distance, and may even cause the vehicle to lose control. Through the second correction operation, it is possible to better adapt to different road conditions and driving habits, provide safer and more effective braking performance, and help improve the safety and reliability of the vehicle under various working conditions.

[0054] Furthermore, when the vehicle is parked, the vehicle is kept stationary based on the left rear brake and the right rear brake.

[0055] Specifically, when the vehicle is parked, the left rear brake and the right rear brake can be controlled to clamp the left rear wheel and the right rear wheel respectively to prevent the vehicle from moving, thereby achieving braking of the vehicle.

[0056] Figure 2 It is a functional block diagram of a braking system for a four-motor independently driven electric vehicle provided according to an embodiment of the present disclosure.

[0057] like Figure 2 As shown, a braking system 200 for a four-motor independently driven electric vehicle provided according to an embodiment of the present disclosure includes a first controller module 201 and a second controller module 202 .

[0058] Specifically, the first controller module 201 is used to periodically obtain the total braking torque required by the four drive motors based on the received braking intention signal; determine the braking target torque of each drive motor based on the total braking torque and the status information of the whole vehicle; determine whether to correct the braking target torque of each drive motor based on at least the braking target torque of each drive motor, its corresponding maximum torque limit, speed information and the actually output first braking torque, and control each drive motor to achieve service braking.

[0059] Specifically, the second controller module 202 is used to keep the vehicle stationary based on the left rear brake and the right rear brake when the vehicle is parked.

[0060] In order to better describe the braking system for a four-motor independently driven electric vehicle provided by the embodiment of the present disclosure, Figure 3 Taking a four-motor independently driven electric vehicle as an example, a braking system is described in detail.

[0061] like Figure 3 As shown, a braking system 300 for a four-motor independently driven electric vehicle provided according to an embodiment of the present disclosure includes a brake pedal module 301 , a drive motor module 302 , a rear brake module 303 , and an EPB controller module 304 .

[0062] Specifically, the brake pedal module 301 may be an electronic brake pedal, which is used to convert a signal generated by a driver stepping on the electronic brake pedal into an electrical signal and transmit it to the drive motor module 302 .

[0063] Specifically, the drive motor module 302 includes 4 motor controllers (MCU1, MCU2, MCU3, MCU4), 4 drive motors (drive motor 1, drive motor 2, drive motor 3, drive motor 4), and a reduction mechanism connected to each drive motor, among which MCU1 is the master motor controller, and the remaining MCU2, MCU3, and MCU4 are slave motor controllers.

[0064] During vehicle braking, MCU1 receives the electrical signal transmitted from the brake pedal module, analyzes and extracts the brake pedal opening and the brake pedal opening change rate, and generates the motor braking target torque (i.e. the above-mentioned total braking target torque) according to the brake pedal opening and the opening change rate, and distributes the total braking target torque to the four drive motors. The four drive motors respond to their respective braking target torques respectively, and feed back the output actual torque (i.e. the above-mentioned first braking torque), the maximum torque limit and the motor speed to the main motor controller MCU1 through their respective MCUs, so as to adjust the distribution of the braking target torque of each drive motor in real time.

[0065] Rear brake module 303: adopts rear brake with electronic caliper, receives brake control from EPB controller to realize parking brake.

[0066] EPB controller module 304: during parking brake, provides control signals to the rear brakes (i.e. the aforementioned left rear brake and right rear brake) to control the operation of the rear brakes to achieve parking brake.

[0067] The driving motor module 302 is the first controller module, and the rear brake module 303 and the EPB controller module 304 are the second controller modules.

[0068] Furthermore, the braking system 300 also includes a battery module 305: when the driving motor realizes braking energy recovery, it stores energy; when the motor is driving, it provides energy, and provides energy for other high-voltage electrical appliances of the vehicle.

[0069] The present disclosure also provides an electric vehicle with four independent motor drives, and the electric vehicle with four independent motor drives is braked by using the braking method based on the electric vehicle with four independent motor drives as described above.

[0070] Figure 4 is a schematic diagram illustrating a four-motor independently driven electric vehicle according to an embodiment of the present disclosure.

[0071] like Figure 4 As shown, the four-motor independently driven electric vehicle includes drive motor 1, drive motor 2, drive motor 3 and drive motor 4, and each drive motor is provided with a motor controller (such as MCU1, MCU2, MCU3, MCU4 in the figure). Among them, drive motor 1 is used to drive the left front wheel, drive motor 2 is used to control the right front wheel, drive motor 3 is used to control the left rear wheel, and drive motor 4 is used to control the right rear wheel. The four-motor independently driven electric vehicle eliminates the traditional brakes, wheel speed sensors, ABS actuators, ESC actuators, iBooster and other components of the front wheels. The system reduces the weight of the vehicle and improves the efficiency of the whole vehicle.

[0072] The above-mentioned four-motor independent drive electric vehicle also includes a battery module and an EPB controller. The EPB controller realizes parking brake (i.e. parking brake) by controlling the left rear brake on the left rear wheel and the right rear brake on the right rear wheel respectively.

[0073] As described above, according to the braking method, system and vehicle based on four-motor independently driven electric vehicle described in detail in the attached drawings, the required total braking torque of the four drive motors is obtained by periodically receiving the braking intention signal, and the second braking target torque of each drive motor is corrected according to the total braking torque, the maximum torque limit of each drive motor and the speed information, and then the driving motor is controlled to achieve driving braking. Vehicle braking can be achieved without configuring a hydraulic braking system for the vehicle, which not only reduces the number of braking system components, reduces the cost and weight of the whole vehicle, reduces the energy consumption of the whole vehicle, but also improves the vehicle endurance. By using the motor speed and its rate of change, it is possible to accurately determine whether the wheel is slipping, and adjust the braking target torque of each drive motor accordingly to realize the function of the anti-lock braking system (ABS); when the vehicle is detected to be slipping, the braking target torque distribution of each drive motor is adjusted to effectively control the vehicle trajectory and ensure driving stability; the driving braking function is completely realized by the drive motor braking, so the traditional iBooster device can be eliminated, further reducing the cost of the whole vehicle; the fast response and high braking torque adjustment accuracy of the drive motor make the vehicle braking process more precise, improve the braking efficiency and safety, and because the braking energy can be almost fully recovered, the system significantly reduces the energy consumption of the whole vehicle and improves energy utilization efficiency; the four-motor independent drive system can achieve precise control of each wheel, enhancing the stability and safety of the vehicle under complex road conditions; by eliminating the traditional brakes, wheel speed sensors, ABS actuators, ESC actuators, iBoosters and other components of the front wheels, the system reduces the weight of the vehicle and improves the efficiency of the whole vehicle.

[0074] The system and device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A braking method based on four-motor independently driven electric vehicle, characterized in that: include: periodically obtaining a total braking torque required by four drive motors based on the received braking intention signal; Determining a braking target torque of each of the driving motors based on the total braking torque and the state information of the entire vehicle; At least based on the braking target torque of each driving motor, its corresponding maximum torque limit, speed information and the actually output first braking torque, the braking target torque of each driving motor is corrected, and each driving motor is controlled to achieve service braking.

2. The braking method based on four-motor independent drive electric vehicle according to claim 1 is characterized in that: The step of periodically obtaining the total braking torque required by the four drive motors based on the received braking intention signal includes: periodically acquiring pedal opening information based on the received braking intention signal; The total braking torque required by the four driving motors is obtained based on the pedal opening information.

3. The braking method based on four-motor independent drive electric vehicle according to claim 1 is characterized in that: The vehicle status information includes vehicle load information; The step of determining the braking target torque of each of the driving motors based on the total braking torque and the state information of the entire vehicle includes: Determine the front axle load and the rear axle load of the vehicle based on the load information of the vehicle; The braking target torque of each of the driving motors is determined based on the total braking torque, the front axle load, and the rear axle load.

4. The braking method based on four-motor independent drive electric vehicle according to claim 1, characterized in that: The correcting of the braking target torque of each of the driving motors includes a first correcting operation and a second correcting operation; The first correction operation is: if the braking target torque of at least one of the driving motors is greater than its corresponding maximum torque limit, replacing the braking target torque of at least one of the driving motors with the maximum torque limit; Alternatively, if the braking target torque of each of the driving motors is not greater than its corresponding maximum torque limit, then the braking target torque of each of the driving motors is not corrected; The second correction operation is: if it is determined based on the rotation speed information of each of the drive motors that the wheel corresponding to at least one of the drive motors is in a slipping state, based on the first braking torque actually outputted by at least one of the drive motors and the anti-skid correction coefficient, adjusting the braking target torque of at least one of the drive motors; Alternatively, if it is determined based on the rotation speed information of each of the driving motors that the wheels corresponding to each of the driving motors are not in a slipping state, the braking target torque of each of the driving motors is not adjusted.

5. The braking method based on four-motor independently driven electric vehicle according to claim 4, the method further comprising: When the first correction operation and the second correction operation are performed on the braking target torque of each driving motor, it is ensured that the braking target torque of each driving motor is not greater than the corresponding maximum torque limit value.

6. The braking method based on four-motor independent drive electric vehicle according to claim 1, characterized in that: The method further comprises: When the vehicle is parked, the vehicle is kept stationary based on the left rear brake and the right rear brake.

7. A braking system for a four-motor independently driven electric vehicle, characterized in that: The invention comprises a first controller module, wherein the first controller module is used for: periodically obtaining a total braking torque required by four drive motors based on the received braking intention signal; Determining a braking target torque of each of the driving motors based on the total braking torque and the state information of the entire vehicle; At least based on the braking target torque of each drive motor, its corresponding maximum torque limit, speed information and the actually output first braking torque, determine whether to correct the braking target torque of each drive motor, and control each drive motor to achieve service braking.

8. The braking system for a four-motor independently driven electric vehicle according to claim 7, characterized in that: The braking system further comprises: The second controller module is used to keep the whole vehicle stationary based on the left rear brake and the right rear brake when the whole vehicle is parked.

9. A four-motor independently driven electric vehicle, characterized in that: The four-motor independently driven electric vehicle is braked using the braking method based on the four-motor independently driven electric vehicle according to any one of claims 1 to 6.

10. The four-motor independently driven electric vehicle according to claim 9, characterized in that: The four-motor independently driven electric vehicle has only a left rear brake and a right rear brake.

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