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

Abstract

The present disclosure relates to the technical field of vehicle braking, in particular to a braking method, system and vehicle based on four-motor independent driving electric vehicle. The braking method comprises: periodically obtaining total braking torque required by four driving motors based on received braking intention signal; determining braking target torque of each driving motor based on total braking torque and state information of the vehicle; correcting braking target torque of each driving motor based on braking target torque of each driving motor, corresponding maximum torque limit value, speed information and actual output first braking torque, and controlling each driving motor to realize service braking. The present disclosure controls each driving motor to realize service braking, without configuring hydraulic braking system for the vehicle, thereby not only reducing the number of braking system components, reducing the cost and weight of the vehicle, reducing the energy consumption of the vehicle, but also improving the endurance of the vehicle.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle braking technology, and more particularly to a braking method, system, and vehicle based on a four-motor independently driven electric vehicle. Background Technology

[0002] In the existing technology, the braking system of electric vehicles mostly adopts a combination of hydraulic braking and electric motor braking to achieve braking.

[0003] However, for electric vehicles with four independent motor drives, many functions of hydraulic braking can be achieved by electric motor braking. If a separate hydraulic braking system is installed, it will not only increase the cost of the vehicle, but also increase the weight of the vehicle, thus increasing energy consumption. This contradicts the goal of OEMs to reduce vehicle cost and energy consumption. Summary of the Invention

[0004] In view of the above-mentioned technical problems, this disclosure provides a braking method, system and vehicle based on a four-motor independently driven electric vehicle.

[0005] According to one aspect of this disclosure, a braking method for a four-motor independently driven electric vehicle is provided, comprising: periodically acquiring 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 the vehicle's state information; determining whether to correct the braking target torque of each drive motor based on the braking target torque of each drive motor, its corresponding maximum torque limit, and speed information, and controlling each drive motor to achieve service braking.

[0006] Furthermore, according to one aspect of the present disclosure, a braking method for a four-motor independently driven electric vehicle 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] Furthermore, according to one aspect of the present disclosure, the braking method for a four-motor independently driven electric vehicle includes vehicle state information including vehicle load information; determining the target braking torque for each drive motor based on the total braking torque and the vehicle state information includes: determining the front axle load and rear axle load of the vehicle based on the vehicle load information; and determining the target braking torque for each drive motor based on the total braking torque, the front axle load, and the rear axle load.

[0008] Furthermore, according to one aspect of the braking method for a four-motor independently driven electric vehicle, 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 as follows: if the braking target torque of at least one drive motor is greater than its corresponding maximum torque limit, then the braking target torque of at least one drive motor is replaced with the maximum torque limit; or, if the braking target torque of each drive motor is not greater than its corresponding maximum torque limit, then the braking target torque of each drive motor is not corrected. The second correction operation is as follows: if, based on the rotational speed information of each drive motor, it is determined 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 output by at least one drive motor and the anti-slip correction coefficient; or, if, based on the rotational speed information of each drive motor, it is determined that the wheel corresponding to each drive motor is not in a slipping state, then the braking target torque of each drive motor is not adjusted.

[0009] Furthermore, according to one aspect of the present disclosure, a braking method for a four-motor independently driven electric vehicle further includes ensuring that, during the first and second correction operations of the braking target torque of each drive motor, the braking target torque of each drive motor does not exceed its corresponding maximum torque limit.

[0010] Furthermore, according to one aspect of the present disclosure, a braking method for a four-motor independently driven electric vehicle further includes: when the vehicle is stopped and braked, keeping the vehicle stationary based on the left rear brake and the right rear brake.

[0011] According to another aspect of this disclosure, a braking system for a four-motor independently driven electric vehicle is provided, characterized in that it includes a first controller module, the first controller module being configured to: periodically acquire the total braking torque required by the four drive motors based on a received braking intention signal; determine the braking target torque of each drive motor based on the total braking torque and the vehicle's state information; and determine whether to correct the braking target torque of each drive motor based at least on the braking target torque of each drive motor, its corresponding maximum torque limit, speed information, and the actual output first braking torque, thereby controlling each drive motor to achieve service braking.

[0012] Furthermore, according to another aspect of this disclosure, a braking system for a four-motor independently driven electric vehicle further includes: a second controller module for keeping the vehicle stationary based on the left and right rear brakes when the vehicle is stopped by braking.

[0013] According to another aspect of this disclosure, a four-motor independently driven electric vehicle is provided, which uses the above-described braking method based on the four-motor independently driven electric vehicle for braking.

[0014] Furthermore, according to another aspect of this disclosure, the four-motor independently driven electric vehicle has only a left rear brake and a right rear brake.

[0015] The braking method, system, and vehicle based on a four-motor independently driven electric vehicle disclosed herein obtain the required total braking torque of the four drive motors by periodically receiving braking intention signals. Based on the total braking torque, the maximum torque limit of each drive motor, and speed information, the second braking target torque of each drive motor is corrected, thereby achieving vehicle braking by controlling the drive motors. This eliminates the need for a hydraulic braking system, reducing the number of braking system components, lowering overall vehicle cost and weight, reducing overall vehicle energy consumption, and improving overall vehicle range. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart illustrating a braking method for a four-motor independently driven electric vehicle according to an embodiment of the present disclosure.

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

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

[0021] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0022] Currently, electric vehicle braking systems generally employ a combination of hydraulic braking and electric motor braking. There are two main methods for implementing hydraulic braking. One method combines a vacuum booster, vacuum pump, and hydraulic braking system. This method not only provides a poor driving experience but also wastes most of the braking energy by converting it into heat. The other method integrates the iBooste intelligent braking system with the hydraulic braking system. This approach achieves better braking energy recovery, helping to reduce overall vehicle energy consumption. However, for electric vehicles with four independently driven motors, many functions of hydraulic braking can actually be replaced by electric motor braking. If a separate hydraulic braking system is still configured, this will result in functional overlap between hydraulic and electric motor braking, leading to redundancy in braking components such as brakes, wheel speed sensors, ESC actuators, and iBooste. This will not only increase the manufacturing cost of the vehicle but also its weight, further increasing energy consumption. This contradicts the current goals of vehicle manufacturers to reduce overall vehicle costs and energy consumption.

[0023] To address the aforementioned technical issues, this disclosure provides a braking method for an electric vehicle based on four independently driven motors.

[0024] Figure 1 This is a schematic flowchart illustrating a braking method for a four-motor independently driven electric vehicle according to an embodiment of the present disclosure.

[0025] like Figure 1 As shown, the braking method for a four-motor independently driven electric vehicle according to an embodiment of this disclosure specifically includes the following steps.

[0026] Step S101: Periodically obtain the total braking torque required by the four drive motors based on the received braking intention signal.

[0027] In one embodiment of this disclosure, the braking intention signal is key information for identifying the driver's braking intention, primarily derived from the driver's operational behavior and vehicle status monitoring. These signals include, but are not limited to, the displacement and rate of change of the brake pedal, the release speed and displacement change of the accelerator pedal, vehicle speed and gear information, and vehicle dynamic responses such as deceleration and wheel speed information. Total braking torque refers to the torque required to achieve braking by controlling the four drive motors during vehicle braking. By continuously monitoring the braking intention signal, the desired braking force of the driver can be determined through analysis, and the total target braking torque required by the four drive motors can be calculated accordingly. For example, the driver expresses braking intention by pressing the brake pedal; the displacement and rate of change of the brake pedal can be captured by sensors and converted into electrical signals. By analyzing these electrical signals, the desired braking force of the driver can be determined, and the total target braking torque can be calculated accordingly.

[0028] Step S102: Based on the total braking torque and the vehicle's status information, determine the target braking torque for each drive motor.

[0029] In one embodiment of this 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 condition, etc.), and the vehicle's dynamic response. The target braking torque refers to the braking torque that the drive motor is expected to output in response to a received braking intention signal. After determining the total target braking torque, adjustments can be made based on the total target braking torque and the vehicle's state information to calculate the target braking torque for each drive motor.

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

[0031] In one embodiment of this disclosure, the maximum torque limit refers to the maximum braking torque that the drive motor can provide without damage or overheating. The actual output first braking torque is the actual braking torque generated by the motor. During braking, the target braking torque, maximum torque limit, speed information, and actual output first braking torque of each motor are monitored in real time. Based on the target braking torque of each motor, its corresponding maximum torque limit, speed information, and actual output first braking torque, the target braking torque of each drive motor is adjusted, thereby controlling each drive motor to operate with its corresponding target braking torque as the target, thus achieving vehicle braking by controlling each drive motor.

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

[0033] In one embodiment of this disclosure, the motor controllers of each drive motor transmit the collected maximum torque limit, speed information, and actual output first braking torque data of each drive motor to the main motor controller MCU1 (i.e., the main motor controller among the four drive motors) in real time via the vehicle Controller Area Network (CAN) network. This communication method ensures the real-time performance and reliability of the data, which is crucial for achieving precise vehicle control. Similarly, when adjusting the braking target torque of each drive motor, the main motor controller also sends the corrected braking target torque of the drive motor to the corresponding motor controller of each drive motor via the vehicle CAN network. Here, each drive motor controller controls the corresponding drive motor to operate based on its own driving motor's braking target torque, delivering the regenerative braking energy to the vehicle's battery module, during which the battery module is charged.

[0034] In summary, according to the technical solution provided by the embodiments of this disclosure, this disclosure obtains the required total braking torque of the four drive motors by periodically receiving braking intention signals, and corrects the second braking target torque of each drive motor based on the total braking torque, the maximum torque limit of each drive motor and speed information, thereby achieving vehicle braking by controlling the drive motors. This eliminates the need to equip the car with a hydraulic braking system, which not only reduces the number of braking system components, lowers the overall vehicle cost and weight, and reduces the overall vehicle energy consumption, but also improves the overall vehicle range.

[0035] Furthermore, periodically obtaining the total braking torque required by the four drive motors based on the received braking intention signal includes: 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 presses the brake pedal, a brake pedal electrical signal is generated, which is the braking intention signal. Upon receiving the brake pedal electrical signal, the pedal opening information can be obtained by analyzing the signal, and based on the pedal opening information, the total target braking torque required to control the four drive motors to perform service braking can be calculated.

[0037] In one embodiment of this disclosure, the pedal opening information includes pedal opening and the rate of change of pedal opening. Pedal opening refers to the position of the brake pedal relative to its fully depressed (or fully released) state. Typically, pedal opening is measured as a percentage, where 0% indicates the brake pedal is not depressed at all, and 100% indicates the brake pedal is fully depressed. The rate of change of pedal opening refers to the rate at which the brake pedal opening changes over time. It indicates how quickly the driver depresses or releases the brake pedal. The rate of change can be positive (indicating the brake pedal is being depressed) or negative (indicating the brake pedal is being released), and its magnitude (absolute value) indicates the rate of change. By combining both pedal opening and the rate of change of pedal opening, the total target braking torque required by the vehicle's four drive motors can be calculated.

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

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

[0040] Specifically, load information refers to the weight distribution currently borne by the entire vehicle. Front axle load refers to the weight borne by the front axle of the vehicle, and rear axle load refers to the weight borne by the rear axle of the vehicle. By acquiring the vehicle's load information, the front and rear axle loads can be obtained through measurement or calculation. Using the total target braking torque, front axle load, and rear axle load, the target braking torque allocated to each drive motor can be calculated. For example, by acquiring the vehicle's load information, the front and rear axle loads can be determined, and the total target braking torque can be allocated proportionally to the front and rear axle loads. Initially, an average allocation is used for the drive motors corresponding to the left and right wheels of the front and rear axles, and a second target braking torque is allocated to each drive motor.

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

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

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

[0044] The second correction operation is as follows: if, based on the rotational speed information of each drive motor, it is determined 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 output by at least one drive motor and the anti-slip correction coefficient; or, if, based on the rotational speed information of each drive motor, it is determined that the wheel corresponding to each drive motor is not in a slipping state, the braking target torque of each drive motor is not adjusted.

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

[0046] The first correction operation involves checking the braking target torque of each drive motor to determine if it exceeds the maximum torque limit for that drive motor. This is to ensure that the motors are not damaged due to overload during braking. If, during the check, it is found that the braking target torque of at least one drive motor exceeds its maximum torque limit, then the braking target torque of that drive motor will be corrected and set to the maximum torque limit. For example, if, during the check, it is found that the braking target torque of at least one drive motor exceeds its maximum torque limit, the braking target torque of that drive motor will be modified to the maximum torque limit, and the reduced automatic target torque of that drive motor will be evenly distributed to the other drive motors.

[0047] In one embodiment of this disclosure, the first correction refers to the following: if the target braking torque of all drive motors does not exceed their respective maximum torque limits, then no correction is needed for the target braking torque of these drive motors. In this case, the calculated target braking torque is considered safe and can be directly applied to each motor.

[0048] In one embodiment of this disclosure, the second correction operation refers to: real-time monitoring of the rotational speed information of each drive motor to determine whether the wheel corresponding to each drive motor is slipping. Slipping is typically manifested as an increased difference between the wheel rotational speed and the actual vehicle speed. If at least one wheel corresponding to a drive motor is detected to be slipping, the braking target torque of that drive motor will be adjusted to reduce or eliminate slipping. The adjustment can be based on a new, lower braking target torque calculated from the actual output first braking torque of the drive motor and a preset anti-slip correction coefficient, to reduce the braking force on the slipping wheel, thereby helping the wheel regain traction. The preset anti-slip correction coefficient can be set according to the actual application. This disclosure does not limit this setting. For example, the preset anti-slip correction coefficient can be set to K, where K takes a value of 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-slip correction coefficient K.

[0049] In one embodiment of this disclosure, the second correction operation refers to: if it is detected that none of the wheels corresponding to all drive motors are slipping, then no adjustment is needed to the braking target torque of any drive motor. In this case, the current braking target torque is considered appropriate and can be maintained.

[0050] Furthermore, when performing the first correction operation and the second correction operation on the braking target torque of each drive motor, it is ensured that the braking target torque of each drive motor is not greater than its corresponding maximum torque limit.

[0051] Specifically, during the first and second correction operations for the braking target torque of each drive motor, it is crucial to ensure that the corrected braking target torque does not exceed the maximum torque limit of each motor. The "maximum torque limit" refers to the maximum braking torque that the motor can provide without damage. The primary purpose of the correction operation is to protect the drive motor from damage. Motors have a physical maximum torque capacity; exceeding this limit may lead to overheating, damage, or failure. By ensuring that the braking target torque does not exceed the maximum torque limit, the braking system can operate within a safe range, avoiding potential safety risks due to overload. Both the first and second correction operations are performed dynamically. After each calculation of the braking target torque, checks and necessary corrections are 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, then the braking target torque of that drive motor will be corrected to the maximum torque limit to ensure that it does not exceed the motor's maximum capacity. For the second correction operation: If wheel slippage is detected for a drive motor during monitoring, the target braking torque of that motor will be adjusted based on the actual output braking torque and the anti-slippage correction coefficient. However, the adjusted torque must still not exceed the maximum torque limit. These two correction operations need to be considered comprehensively, both to prevent motor overload and to address wheel slippage. This means that while adjusting the braking torque to prevent slippage, 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 target braking 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 during the second correction operation, it is necessary to check again whether the target braking torque of these motors exceeds their maximum torque limits.

[0052] This comprehensive correction strategy enables the provision of effective braking force while ensuring motor safety, thereby improving the braking performance and safety of electric vehicles. This method is particularly suitable for electric vehicles with four independently driven motors, as each motor can be controlled independently, resulting in more precise and flexible braking control.

[0053] In summary, according to the technical solution provided in this disclosure, the purpose of the first correction operation is to ensure that during braking, the target braking torque of each drive motor does not exceed its physical maximum bearing capacity, i.e., 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; after each calculation of the target braking torque, checks and necessary corrections are made to adapt to real-time changes in driving conditions and vehicle status. Through this first correction operation, effective braking force can be provided while ensuring the safety of the drive motor, thereby improving the braking performance and safety of the electric vehicle. Furthermore, the purpose of the second correction operation is to address wheel slippage that may occur during braking. Slippage reduces braking efficiency, increases braking distance, and may even lead to loss of vehicle control. Through the second correction operation, it is possible to better adapt to different road conditions and driving habits, providing safer and more effective braking performance, and helping to improve the safety and reliability of the vehicle under various operating conditions.

[0054] Furthermore, when the vehicle comes to a complete stop, the left and right rear brakes keep the vehicle stationary.

[0055] Specifically, when the vehicle is stopped and braked, the left and right rear brakes can be controlled to clamp the left and right rear wheels respectively, preventing the vehicle from moving and thus achieving vehicle braking.

[0056] Figure 2 This 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, the 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 vehicle's state information; and determine whether to correct the braking target torque of each drive motor based at least on the braking target torque of each drive motor, its corresponding maximum torque limit, speed information, and the actual 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 and right rear brakes when the vehicle is stopped and braked.

[0060] To better describe the braking system for a four-motor independently driven electric vehicle provided in the embodiments of this disclosure, Figure 3 For example, a braking system for a four-motor independently driven electric vehicle 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 can be an electronic brake pedal, used to convert the signal of the driver pressing 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 four motor controllers (MCU1, MCU2, MCU3, MCU4), four drive motors (drive motor 1, drive motor 2, drive motor 3, drive motor 4), and a reduction mechanism connected to each drive motor. MCU1 is the master motor controller, and the other three MCUs (MCU2, MCU3, MCU4) are slave motor controllers.

[0064] During vehicle braking, MCU1 receives electrical signals from the brake pedal module, analyzes and extracts the brake pedal opening degree and the rate of change of the brake pedal opening degree, and generates the target braking torque for the motor (i.e., the total target braking torque mentioned above) based on the brake pedal opening degree and the rate of change of the opening degree. The total target braking torque is then distributed to the four drive motors. The four drive motors respond to their respective target braking torques and feed back the actual output torque (i.e., the first braking torque mentioned above), 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 target braking torque of each drive motor in real time.

[0065] Rear brake module 303: Employs a rear brake with electronic calipers, receiving braking control from the EPB controller to achieve parking braking.

[0066] EPB controller module 304: When parking, it provides control signals to the rear brakes (i.e., the aforementioned left and right rear brakes) to control the rear brakes to operate and achieve parking braking.

[0067] Among them, the drive motor module 302 is the first controller module mentioned above, and the rear brake module 303 and the EPB controller module 304 are the second controller modules mentioned above.

[0068] Furthermore, the braking system 300 also includes a battery module 305: it stores energy when the drive motor performs braking energy recovery; it provides energy when the motor is driven; and it provides energy to other high-voltage electrical components in the vehicle.

[0069] This disclosure also provides a four-motor independently driven electric vehicle, which is braked using the braking method described above for a four-motor independently driven electric vehicle.

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

[0071] like Figure 4 As shown, this four-motor independently driven electric vehicle includes drive motor 1, drive motor 2, drive motor 3, and drive motor 4. Each drive motor is equipped with a motor controller (MCU1, MCU2, MCU3, and MCU4 in the figure). Drive motor 1 drives the left front wheel, drive motor 2 controls the right front wheel, drive motor 3 controls the left rear wheel, and drive motor 4 controls the right rear wheel. This four-motor independently driven electric vehicle eliminates traditional front wheel brakes, wheel speed sensors, ABS actuators, ESC actuators, iBoosters, and other components, reducing vehicle weight and improving overall vehicle efficiency.

[0072] The aforementioned four-motor independently driven electric vehicle also includes a battery module and an EPB controller. The EPB controller achieves parking braking (i.e., parking brake) by separately controlling the left rear brake on the left rear wheel and the right rear brake on the right rear wheel.

[0073] The braking method, system, and vehicle based on a four-motor independently driven electric vehicle described above in detail with reference to the accompanying drawings, obtains the required total braking torque of the four drive motors by periodically receiving braking intention signals. Based on the total braking torque, the maximum torque limit of each drive motor, and speed information, the second braking target torque of each drive motor is corrected, and then the driving motors are controlled to achieve vehicle braking. This eliminates the need for a hydraulic braking system, thereby reducing the number of braking system components, lowering overall vehicle cost and weight, reducing overall vehicle energy consumption, and improving overall vehicle range. By utilizing the motor speed and its rate of change, it is possible to accurately determine whether the wheels are slipping, and adjust the braking target torque of each drive motor accordingly to achieve the function of the anti-lock braking system (ABS). When vehicle slippage is detected, the system effectively controls the vehicle trajectory and ensures driving stability by adjusting the braking target torque distribution of each drive motor. The service braking function is entirely achieved by the drive motor braking, thereby eliminating the need for the traditional iBooster device and further reducing the overall vehicle cost. The drive motor's fast response and high braking torque adjustment accuracy make the vehicle braking process more precise, improving braking efficiency and safety. Furthermore, since braking energy can be almost fully recovered, the system significantly reduces overall vehicle energy consumption and improves energy utilization efficiency. The four-motor independent drive system enables precise control of each wheel, enhancing the vehicle's stability and safety under complex road conditions. By eliminating components such as the traditional front brakes, wheel speed sensors, ABS actuators, ESC actuators, and iBooster, the system reduces vehicle weight and improves overall vehicle efficiency.

[0074] The system and device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A braking method for an electric vehicle based on four independently driven motors, characterized in that, include: The total braking torque required by the four drive motors is periodically obtained based on the received braking intention signal; Based on the total braking torque and the vehicle's status information, the target braking torque for each drive motor is determined. Based at least on the braking target torque of each drive motor, its corresponding maximum torque limit, speed information and actual output first braking torque, the braking target torque of each drive motor is corrected to control each drive motor to achieve service braking; The correction of the braking target torque for each of the drive motors includes a first correction operation and a second correction operation. The first correction operation is as follows: if the braking target torque of at least one of the drive motors is greater than its corresponding maximum torque limit, then the braking target torque of at least one of the drive motors is replaced with the maximum torque limit. Alternatively, if the target braking torque of each of the drive motors is not greater than its corresponding maximum torque limit, then the target braking torque of each of the drive motors is not corrected. The second correction operation is as follows: if, based on the rotation speed information of each drive motor, it is determined 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 output by at least one drive motor and the anti-slip correction coefficient. Alternatively, if it is determined, based on the rotational speed information of each drive motor, that none of the wheels corresponding to each drive motor are slipping, then the braking target torque of each drive motor is not adjusted.

2. The braking method for an electric vehicle based on four independently driven motors according to claim 1, characterized in that, The process of periodically obtaining the total braking torque required by the four drive motors based on the received braking intention signal includes: Periodically acquire pedal opening information based on the received braking intention signal; Based on the pedal opening information, the total braking torque required by the four drive motors is obtained.

3. The braking method for an electric vehicle based on four independently driven motors according to claim 1, characterized in that, The vehicle's status information includes the vehicle's load information; The step of determining the target braking torque for each drive motor based on the total braking torque and the vehicle's state information includes: Based on the vehicle's load information, the front axle load and rear axle load of the vehicle are determined. The target braking torque for each of the drive motors is determined based on the total braking torque, the front axle load, and the rear axle load.

4. The braking method for a four-motor independently driven electric vehicle according to claim 1, the method further includes: When performing the first correction operation and the second correction operation on the braking target torque of each drive motor, ensure that the braking target torque of each drive motor is not greater than its corresponding maximum torque limit.

5. The braking method for an electric vehicle based on four independently driven motors according to claim 1, characterized in that, The method further includes: When the vehicle comes to a stop, the vehicle remains stationary based on the left and right rear brakes.

6. A braking system for a four-motor independently driven electric vehicle, characterized in that, Includes a first controller module, the first controller module being used for: The total braking torque required by the four drive motors is periodically obtained based on the received braking intention signal; Based on the total braking torque and the vehicle's status information, the target braking torque for each drive motor is determined. Based at least on the braking target torque of each drive motor, its corresponding maximum torque limit, speed information and actual output first braking torque, it is determined whether to correct the braking target torque of each drive motor and control each drive motor to achieve service braking. The braking target torque of each of the drive motors is corrected, including a first correction operation and a second correction operation; The first correction operation is as follows: if the braking target torque of at least one of the drive motors is greater than its corresponding maximum torque limit, then the braking target torque of at least one of the drive motors is replaced with the maximum torque limit. Alternatively, if the target braking torque of each of the drive motors is not greater than its corresponding maximum torque limit, then the target braking torque of each of the drive motors is not corrected. The second correction operation is as follows: if, based on the rotation speed information of each drive motor, it is determined 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 output by at least one drive motor and the anti-slip correction coefficient. Alternatively, if it is determined, based on the rotational speed information of each drive motor, that none of the wheels corresponding to each drive motor are slipping, then the braking target torque of each drive motor is not adjusted.

7. The braking system for a four-motor independently driven electric vehicle according to claim 6, characterized in that, The braking system also includes: The second controller module is used to keep the vehicle stationary based on the left and right rear brakes when the vehicle is stopped and braked.

8. A four-motor independently driven electric vehicle, characterized in that, The four-motor independently driven electric vehicle is braked using the braking method for a four-motor independently driven electric vehicle as described in any one of claims 1-5.

9. The four-motor independently driven electric vehicle according to claim 8, characterized in that, The four-motor independently driven electric vehicle only has a left rear brake and a right rear brake.

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