Control method for comfort braking of electric vehicle, and vehicle controller and electric vehicle

Abstract

Provided in the present application are a control method for comfort braking of an electric vehicle, a vehicle controller and an electric vehicle, which are applied to the technical field of vehicles, so as to reduce the shaking of the electric vehicle during braking. The method comprises: at a first moment, when an opening degree of a brake pedal increases to be greater than a preset opening degree, controlling a driving electric motor to output a first braking force, and controlling a braking apparatus to output a second braking force; when a vehicle speed decreases to be less than or equal to a first preset vehicle speed, controlling one of the first braking force and the second braking force to decrease; and at a third moment after a second moment, controlling the other of the first braking force and the second braking force to decrease. In this way, during braking, braking forces output by a driving electric motor and a braking apparatus are coordinated, so that the energy recovery performance of the driving electric motor is effectively utilized to improve a vehicle cruising range, and the high braking precision of the driving electric motor is also effectively utilized to reduce the shaking of an electric vehicle during braking, thereby achieving comfort braking of the electric vehicle.

Description

Control methods for comfort braking of electric vehicles, vehicle controllers and electric vehicles

[0001] This application claims priority to Chinese Patent Application No. 202411999350.3, filed with the State Intellectual Property Office of China on December 31, 2024, entitled "Control Method for Comfort Braking of Electric Vehicle, Vehicle Controller and Electric Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of vehicle technology, and in particular to a control method for comfort braking of an electric vehicle, a vehicle controller, and an electric vehicle. Background Technology

[0003] With the development of electric vehicles, the driving experience of electric vehicles has received increasing attention. Among these factors, the braking performance of electric vehicles is a key factor affecting the driving experience. During the braking process of electric vehicles, especially at the end of braking, there is a noticeable swaying phenomenon.

[0004] To reduce vehicle sway during braking, a method is used to control the release of a certain amount of wheel-end braking force by appropriately reducing the hydraulic pressure of the braking device at the end of braking, thereby reducing the vehicle's deceleration. However, due to the low control precision of hydraulic control, there is a problem of insufficient control precision in the braking force output by the braking device during braking. As a result, it is difficult to effectively suppress the swaying phenomenon of electric vehicles during braking, affecting the user's driving experience. Summary of the Invention

[0005] This application provides a control method for comfortable braking of an electric vehicle, a vehicle controller, and an electric vehicle, used to control the drive motor and braking device of the electric vehicle during braking to reduce the swaying of the electric vehicle during braking and improve the user's driving experience.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions.

[0007] In a first aspect, this application provides a control method for comfortable braking of an electric vehicle. This control method is used to control a first braking force output by the drive motor of the electric vehicle or a second braking force output by the braking device during braking when the deceleration of the electric vehicle is less than a preset deceleration, thereby reducing the swaying of the electric vehicle during braking. The control method includes: at a first moment during the braking process of the electric vehicle, increasing the opening of the brake pedal to a value greater than a preset opening, controlling the drive motor to output the first braking force and controlling the braking device to output the second braking force; at a second moment after the first moment, decreasing the speed of the electric vehicle to a value less than or equal to a first preset speed, controlling a decrease in one of the first and second braking forces; and at a third moment after the second moment, controlling a decrease in the other of the first and second braking forces.

[0008] In this embodiment, during the braking process of the electric vehicle, the drive motor is controlled to output braking force. Since some of the drive motor's kinetic energy is recovered when outputting braking force, it can be used for subsequent vehicle movement or other onboard equipment, improving the energy efficiency of the electric vehicle. Furthermore, when the electric vehicle's speed decreases to less than or equal to a first preset speed, i.e., the electric vehicle enters the final stage of braking, the first braking force output by the drive motor or the second braking force output by the braking device is reduced. Because the braking control precision of the drive motor is higher than that of the braking device, the swaying phenomenon caused by the rapid change in vehicle speed and insufficient braking control precision during braking is reduced. Thus, by coordinating the braking forces output by the drive motor and the braking device during braking, not only is the energy recovery performance of the drive motor effectively utilized, increasing the vehicle's range, but the high braking precision of the drive motor is also effectively utilized, reducing the swaying phenomenon during braking and achieving comfortable braking, thereby improving the user's driving experience.

[0009] In one embodiment, the control method specifically includes: at a third time after the second time, reducing one of the first braking force and the second braking force to less than or equal to a preset braking force, and controlling the other of the first braking force and the second braking force to decrease.

[0010] In this embodiment, by coordinating the first braking force output by the drive motor and the second braking force output by the braking device, the deceleration of the electric vehicle can be stably reduced during braking, thereby reducing the swaying phenomenon caused by the rapid change in vehicle speed during braking and achieving comfortable braking of the electric vehicle.

[0011] In one embodiment, the control method specifically includes: controlling the second braking force to decrease at a second time after the first time; and controlling the first braking force to decrease at a third time after the second time.

[0012] In this embodiment, the higher the proportion of the first braking force in the total braking force, the higher the energy recovery efficiency of the electric vehicle during braking. By reducing the second braking force output by the braking device, and then reducing the first braking force output by the drive motor, the proportion of the first braking force output by the drive motor in the total braking force is ensured, maximizing the vehicle's driving range. Furthermore, since the braking control precision of the drive motor is higher than that of the braking device, reducing the first braking force output by the drive motor allows for effective utilization of the drive motor's high braking precision at the end of braking, reducing the swaying phenomenon of the electric vehicle during braking and achieving comfortable braking for the electric vehicle.

[0013] In one embodiment, the control method further includes: after the third moment, controlling the sum of the first braking force and the second braking force to decrease simultaneously with the speed of the electric vehicle to zero.

[0014] In this embodiment, as the speed of the electric vehicle gradually decreases during braking, the vehicle body will maintain a forward motion trend due to inertia. By controlling the sum of the first braking force and the second braking force to be reduced to zero in coordination with the vehicle speed, the deceleration of the electric vehicle can be reduced uniformly during braking, reducing the abruptness of the electric vehicle during braking and avoiding swaying caused by the mismatch between inertia and braking force, thereby improving the comfortable braking performance of the electric vehicle.

[0015] In one embodiment, the control method further includes: between the second and third time points, the greater the speed of the electric vehicle, the smaller the rate of decrease of either the first braking force or the second braking force.

[0016] In this embodiment, the rate of decrease of one of the first braking force and the second braking force decreases as the speed of the electric vehicle increases, ensuring that the deceleration and speed of the electric vehicle can gradually decrease to zero simultaneously. This avoids sudden changes in deceleration and speed during braking, thereby reducing the abruptness of the electric vehicle during braking, reducing the swaying phenomenon of the electric vehicle during braking, and improving the user's driving experience.

[0017] In one embodiment, the control method specifically includes: at a first moment during the braking process of the electric vehicle, the opening of the brake pedal is less than or equal to a preset opening, and the first braking force is controlled to increase as the opening of the brake pedal increases; at a first moment during the braking process of the electric vehicle, the opening of the brake pedal is greater than the preset opening, and the first braking force is controlled not to increase as the opening of the brake pedal increases.

[0018] In this embodiment, since the total braking force indicated by the brake pedal when the brake pedal opening is at a preset opening is the maximum permissible braking force provided to the electric vehicle when the drive motor outputs the maximum permissible negative torque, when the brake pedal opening is greater than the preset opening, the first braking force is controlled not to increase with the increase of the brake pedal opening, so that the braking force output by the drive motor is not higher than its maximum permissible braking force. This ensures the energy utilization efficiency of the electric vehicle while also ensuring the safe and effective operation of the drive motor during braking.

[0019] In one embodiment, the control method further includes: at a fourth time after the third time, the vehicle speed of the electric vehicle decreases to zero, and the second braking force output by the control braking device increases.

[0020] In this embodiment, by immediately increasing the second braking force output by the braking device after the electric vehicle stops, vehicle movement caused by gaps in the transmission system and components is avoided, thereby ensuring that the electric vehicle remains stationary.

[0021] In one embodiment, the control method specifically includes: at a fourth moment, controlling the second braking force output by the braking device to increase to be greater than the braking force output by the braking device at the first moment.

[0022] In this embodiment, at the fourth moment, when the second braking force output by the control braking device increases, the second braking force is controlled to be greater than the braking force output by the braking device at the first moment. This not only avoids vehicle movement caused by the gaps in the transmission system and components, but also avoids the phenomenon of the electric vehicle slipping due to the difficulty in overcoming the component of gravity along the slope direction when it is on a slope, thus ensuring that the electric vehicle is stationary.

[0023] In one embodiment, the control method further includes: at a fifth time after the fourth time, the opening of the brake pedal is reduced to zero, and the second braking force output by the control braking device is reduced to zero.

[0024] In this embodiment, the opening of the brake pedal is reduced to zero, and the second braking force output by the control braking device is reduced to zero. By increasing the braking force at the moment of stopping and controlling the second braking force to be reduced to zero after stopping, the electric vehicle can remain stable and stationary after stopping without swaying back and forth.

[0025] In one embodiment, the control method further includes: during braking when the deceleration of the electric vehicle is greater than or equal to a preset deceleration, controlling the first braking force output by the drive motor to increase or remain unchanged until the speed of the electric vehicle decreases to zero.

[0026] In this embodiment, when the deceleration of the electric vehicle is greater than or equal to the preset deceleration, the electric vehicle is in emergency braking mode. Therefore, at this time, the vehicle controller no longer controls the first braking force output by the drive motor to decrease, but controls the first braking force output by the drive motor to increase or remain unchanged until the speed of the electric vehicle decreases to zero, thereby ensuring the braking efficiency and braking safety of the electric vehicle during emergency braking.

[0027] Secondly, this application provides a control method for comfortable braking of an electric vehicle. The control method is used to control the first braking force output by the drive motor of the electric vehicle during braking when the deceleration of the electric vehicle is less than a preset deceleration, so as to reduce the swaying of the electric vehicle during braking. The control method includes: at a first moment during the braking process of the electric vehicle, increasing the opening of the brake pedal to less than or equal to a preset opening, and controlling the drive motor to output the first braking force; at a second moment after the first moment, decreasing the speed of the electric vehicle to less than or equal to a second preset speed, and controlling the first braking force to decrease.

[0028] In this embodiment, during the braking process of the electric vehicle, when the opening of the brake pedal increases to less than or equal to the preset opening, only the drive motor is controlled to output the first braking force and the first braking force is adjusted. This not only effectively utilizes the energy recovery performance of the drive motor and improves the overall vehicle range, but also effectively utilizes the high braking precision of the drive motor, reducing the swaying phenomenon of the electric vehicle during braking, achieving comfortable braking of the electric vehicle, and thus improving the user's driving experience.

[0029] In one embodiment, the control method specifically includes: after the second moment, controlling the first braking force and the speed of the electric vehicle to decrease simultaneously to zero.

[0030] In this embodiment, as the speed of the electric vehicle gradually decreases during braking, the vehicle body will maintain a forward motion trend due to inertia. By controlling the first braking force to be reduced to zero in coordination with the vehicle speed, the deceleration of the electric vehicle can be reduced uniformly during braking, reducing the abruptness of the electric vehicle during braking and avoiding swaying caused by the mismatch between inertia and braking force, thereby improving the comfortable braking performance of the electric vehicle.

[0031] Thirdly, embodiments of this application provide a vehicle controller for comfort braking control of an electric vehicle. This vehicle controller is used to control a first braking force output by the drive motor of the electric vehicle or a second braking force output by the braking device during braking when the deceleration of the electric vehicle is less than a preset deceleration. Specifically, during braking of the electric vehicle, in response to the brake pedal opening increasing to a value greater than a preset opening, the vehicle controller controls the drive motor to output the first braking force and controls the braking device to output the second braking force to brake the four wheels of the electric vehicle; in response to the electric vehicle speed decreasing to a value less than or equal to a first preset speed, the vehicle controller controls one of the first and second braking forces to decrease, and then controls the other of the first and second braking forces to decrease.

[0032] Fourthly, embodiments of this application provide a vehicle controller for comfort braking control of an electric vehicle. This vehicle controller controls the first braking force output by the drive motor of the electric vehicle during braking when the deceleration of the electric vehicle is less than a preset deceleration. Specifically, during braking, in response to the brake pedal opening increasing to less than or equal to a preset opening, the vehicle controller controls the drive motor to output the first braking force to brake the four wheels of the electric vehicle; and in response to the electric vehicle speed decreasing to less than or equal to a second preset speed, it controls the first braking force to decrease.

[0033] Fifthly, embodiments of this application provide an electric vehicle, which includes a drive motor, a braking device, and a vehicle controller provided in the third and fourth aspects. The vehicle controller is used to control the drive motor and the braking device to perform the control methods described in the first aspect, any possible implementation of the first aspect, the second aspect, or any possible implementation of the second aspect.

[0034] Understandably, the beneficial effects that the vehicle controller and electric vehicle provided above can achieve can be referred to in the beneficial effects of the electric vehicle comfort braking control method provided in the first and second aspects above, and will not be repeated here. Attached Figure Description

[0035] Figure 1 is a schematic diagram of an electric vehicle 1 provided in an embodiment of this application;

[0036] Figure 2 is a schematic diagram of an architecture of an electric vehicle 1 provided in an embodiment of this application;

[0037] Figure 3 is a schematic diagram of another architecture of the electric vehicle 1 provided in an embodiment of this application;

[0038] Figure 4 is a schematic diagram of the control process of the vehicle controller 410 of the electric vehicle 1 provided in the embodiment of this application;

[0039] Figure 5 is a schematic diagram of the control process of the motor controller 110 of the electric vehicle 1 provided in the embodiment of this application;

[0040] Figure 6 is a schematic diagram of the control process of the brake controller 210 of the electric vehicle 1 provided in the embodiment of this application;

[0041] Figure 7 is a schematic diagram of the braking control process of the electric vehicle 1 provided in an embodiment of this application;

[0042] Figure 8 is a schematic diagram of the braking control process of electric vehicle 1 shown in Figure 7.

[0043] Figure 9 is another schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application;

[0044] Figure 10 is a schematic diagram of the braking control process of electric vehicle 1 shown in Figure 9;

[0045] Figure 11 is another schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application;

[0046] Figure 12 is a schematic diagram of the braking control process of electric vehicle 1 shown in Figure 11;

[0047] Figure 13 is another schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application;

[0048] Figure 14 is a schematic diagram of the braking control process of electric vehicle 1 shown in Figure 13.

[0049] Figure 15 is a schematic diagram of the operation of the electric vehicle 1 in emergency braking mode according to an embodiment of this application;

[0050] Figure 16 is a schematic diagram of the braking control process of electric vehicle 1 provided in Figure 15.

[0051] Figure 17 is a flowchart illustrating a comfort braking control method for an electric vehicle 1 provided in an embodiment of this application. Detailed Implementation

[0052] The implementation and use of the various embodiments will be discussed in detail below. However, it should be understood that many applicable inventive concepts provided in this application can be implemented in a variety of specific environments. The specific embodiments discussed are merely illustrative of specific ways of implementing and using this application and technology, and do not limit the scope of this application.

[0053] With the development of electric vehicles, the driving experience has received increasing attention, among which braking performance is a key factor affecting the driving experience. During the braking process of an electric vehicle, the braking force output by the braking device is controlled to brake the four wheels. Furthermore, by reducing the braking force output by the braking device at the end of braking, the tendency of the electric vehicle's center of gravity to shift forward during braking and the vehicle's swaying after stopping can be mitigated, improving the comfort of the electric vehicle during braking. The end of braking refers to the process of the electric vehicle's speed decreasing from a very low level to zero, that is, the process from near stopping to complete stopping with no relative movement to the ground.

[0054] In one possible implementation, during the braking process of an electric vehicle, the braking device is controlled to release a certain amount of wheel-end braking force. This is achieved by reducing the hydraulic pressure of the braking device to decrease the output braking force, and then re-establishing the hydraulic pressure at the moment of stopping to bring the vehicle to a standstill. Adjusting the hydraulic pressure can mitigate the tendency of the vehicle's center of gravity to shift forward during braking and reduce vehicle swaying after stopping. However, due to the low precision of the hydraulic control of the braking device, fluctuations in the brake hydraulic pressure may occur during braking. These fluctuations in fluid pressure can cause instability in the output braking force, meaning the clamping force from the brake pads to the brake disc is unstable, resulting in vehicle swaying during braking and affecting the user's driving experience.

[0055] In one embodiment, the braking device suffers from a pressure build-up delay when the driver depresses the brake pedal. This delay in response time means the braking system cannot provide sufficient braking force promptly after the driver presses the brake pedal, potentially causing the driver to apply even more pressure and exacerbating the swaying during braking. The pressure build-up delay is the time delay between the driver pressing the brake pedal and the establishment of effective hydraulic pressure in the braking device. Furthermore, in low-speed, stop-and-go driving conditions, the electric vehicle's speed changes frequently and slightly. The braking device struggles to accurately provide appropriate braking force based on the vehicle's speed and the driver's intentions, making it prone to maintaining a large braking force, leading to excessive deceleration and swaying of the vehicle.

[0056] In one possible implementation, the braking force output by the braking device remains constant during the braking process of the electric vehicle, while the drive motor of the electric vehicle outputs a certain positive torque to reduce the deceleration of the entire vehicle, thereby suppressing the swaying phenomenon during the braking process. However, adjusting the deceleration of the electric vehicle will have a negative impact on its energy economy; that is, controlling the output of positive torque by the drive motor will additionally increase the energy consumption of the electric vehicle during braking, thus shortening the vehicle's driving range.

[0057] To address the aforementioned issues, this application provides a control method for comfortable braking of an electric vehicle and a vehicle controller for the electric vehicle. During the braking process of the electric vehicle, the drive motor and braking device are controlled to reduce the vehicle's swaying and improve the user's driving experience.

[0058] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0059] Referring to Figure 1, Figure 1 is a schematic diagram of an electric vehicle 1 provided in an embodiment of this application. As shown in Figure 1, the electric vehicle 1 includes a drive system 100, a braking system 200, and a power battery 300, which supplies power to the drive system 100 and the braking system 200.

[0060] The electric vehicle 1 operates in both a driving state and a braking state. When the electric vehicle 1 is in a driving state, the driving system 100 receives power from the power battery 300 and provides a driving force to the four wheels of the electric vehicle 1 in the same direction as the wheel rotation speed, so that the electric vehicle 1 moves under the driving force. When the electric vehicle 1 is in a braking state, the braking system 200 receives power from the power battery 300 and provides a braking force to the four wheels of the electric vehicle 1 in the opposite direction to the wheel rotation speed, so that the electric vehicle 1 decelerates or stops under the action of the braking force.

[0061] In some implementations, when the electric vehicle 1 is braking, the inverter in the drive system 100 adjusts the current in the stator windings, causing the stator magnetic field to interact with the rotor permanent magnet magnetic field to generate a negative torque opposite to the rotational speed of the wheels of the electric vehicle 1. This provides braking force to the electric vehicle 1, thereby achieving the braking effect. When the drive motor generates negative torque, the kinetic energy of the drive system 100 is converted into electrical energy. This electrical energy is fed back to the power battery 300 for storage through the circuit between the drive system 100 and the power battery 300. This achieves energy recovery of part of the kinetic energy of the electric vehicle 1 during braking, which can then be used for subsequent driving of the electric vehicle 1 or other onboard equipment. This improves the energy utilization efficiency of the electric vehicle 1 and allows the electric vehicle 1 to better utilize the energy that would otherwise be consumed during braking, thereby reducing the overall energy consumption of the electric vehicle 1 and increasing the vehicle's range.

[0062] Understandably, the electric vehicle 1 in this application embodiment can be any of different types of vehicles such as cars, trucks, and passenger buses, or it can be a tricycle, two-wheeled vehicle, train, or other transportation device for carrying people or goods, or other types of vehicles powered by the power battery 300, which are not limited here. Among them, vehicles include, but are not limited to, pure electric vehicles (pure electric vehicle / battery electric vehicle, pure EV / battery EV), hybrid electric vehicles (HEV), range-extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), and new energy vehicles (NEV).

[0063] It is understood that the power battery 300 in this embodiment can be a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-cadmium battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery, etc., and is not limited thereto. In terms of scale, the power battery 300 in this embodiment can be a single cell, a battery module, or a battery pack, and is not limited thereto. The power battery 300 can also supply power to other electrical devices in the electric vehicle 1, such as powering the in-vehicle air conditioner and in-vehicle media player.

[0064] Referring to Figure 2, which is a schematic diagram of the architecture of an electric vehicle 1 provided in an embodiment of this application, the drive system 100, the braking system 200, and the vehicle controller 410 are communicatively connected.

[0065] In one embodiment, the drive system 100 includes a motor controller 110 and a drive motor 120. The motor controller 110 can change the stator magnetic field strength and direction by adjusting the magnitude of the stator winding current and the phase of the three-phase current, thereby changing the interaction force between the stator and rotor of the drive motor 120. The motor controller 110 can be a microcontroller unit (MCU), or it can be a device integrating a microcontroller with a vehicle control unit (VCU), etc., without limitation.

[0066] In driving mode, the inverter circuit in the motor controller 110 converts the DC power output from the power battery 300 into three-phase AC power to supply the stator windings. The current flowing through the stator windings generates a rotating magnetic field. The three-phase currents flow sequentially in the stator windings according to their respective phases, and the magnetic fields generated by the three-phase stator windings combine to form a rotating magnetic field. The direction of the rotating magnetic field is consistent with the phase sequence of the current. The rotor of the drive motor 120 rotates in the direction of the magnetic field rotation, outputting a positive torque in the same direction as the wheel speed of the electric vehicle 1, providing driving force for the electric vehicle 1. In braking mode, the motor controller 110 changes the direction and magnitude of the current supplied to the stator windings. The change in the current flow sequence in the stator windings reverses the direction of the magnetic field rotation, causing the interaction between the stator magnetic field and the rotor magnetic field to become an obstacle to the rotation of the rotor of the drive motor 120, thereby generating a negative torque opposite to the wheel speed of the electric vehicle 1, providing braking force for the electric vehicle 1. The motor controller 110 collects the magnitude of the three-phase current in the inverter circuit through current sensors, which allows it to determine the magnitude of the positive or negative torque output by the drive motor 120.

[0067] The braking system 200 includes a brake controller 210, a braking device 220, and a brake pedal 230. The braking device 220 is used to brake the four wheels of the electric vehicle 1. When the user presses the brake pedal 230 of the electric vehicle 1, the vehicle controller 410 generates a braking signal based on the opening degree of the brake pedal 230. The drive motor 120 and / or the braking device 220 output braking force to the wheels of the electric vehicle 1 according to the braking value indicated by the braking signal, so as to reduce the speed of the electric vehicle 1. During the braking process of the electric vehicle 1, the larger the opening degree of the brake pedal 230, the larger the braking value indicated by the braking signal, the greater the braking force output by the drive motor 120 and / or the braking device 220, and the greater the deceleration of the electric vehicle 1, that is, the faster the speed of the electric vehicle 1 decreases. The brake controller 210 in the braking system 200 can be a microcontroller or the vehicle controller 410. The brake controller 210 can also be integrated with the motor controller 110 in the drive system 100 to form a domain control unit (DCU) in the electric vehicle 1, which is not limited here. The braking device 220 may be an electronic hydraulic brake (EHB), an electronic mechanical brake (EMB), or other types of braking devices 220, without limitation.

[0068] In embodiments of this application, the electric vehicle 1 further includes a battery controller 420, which is communicatively connected to the power battery 300. The battery controller 420 monitors the collected state information of the power battery 300, such as voltage, current, temperature, battery charge, and health status. The battery controller 420 also protects the power battery 300 when abnormal state information is detected, such as through overcharge protection, over-discharge protection, and overcurrent protection. In the electric vehicle 1, the battery controller 420 can also be communicatively connected to the vehicle controller 410. The battery controller 420 transmits the state information of the power battery 300 to the vehicle controller 410 of the electric vehicle 1 and receives control commands (such as charging power control) from the vehicle controller 410. The battery controller 420 can be a battery management system (BMS), which comprehensively manages and monitors the power battery 300 to ensure its safe, reliable, and efficient operation.

[0069] In one embodiment, the electric vehicle 1 further includes a brake pedal position sensor 510, which is used to detect the opening degree or pedal travel of the brake pedal 230. The brake pedal position sensor 510 can be a Hall effect type or a variable resistance type. The Hall effect type brake pedal position sensor 510 contains a permanent magnet and a Hall element. The movement of the brake pedal 230 causes the permanent magnet to be displaced, changing the magnetic field strength around the Hall element. The Hall element in the brake pedal position sensor 510 outputs different voltage signals according to the change in the magnetic field. For example, different pedal opening degrees result in different magnetic field changes and different output voltages, accurately reflecting the pedal position, thereby determining the opening degree or pedal travel of the brake pedal 230.

[0070] In one embodiment, the electric vehicle 1 further includes a speed measurement unit 520, which is used to detect the speed of the drive motor 120. The speed measurement unit 520 can be a resolver, a motor speed sensor, etc. The speed measurement unit 520 can be installed on the drive motor 120 (e.g., on the rotor of the motor). In this case, the motor controller 110 can receive the resolver signal and the speed signal of the drive motor 120 from the speed measurement unit 520. The speed signal can be indirectly obtained from the resolver signal. By processing the resolver signal and calculating the change in angle per unit time, the speed signal can be obtained. Furthermore, since the resolver signal can accurately reflect the motor speed, for the electric vehicle 1, the rotational motion of the motor is transmitted to the wheels through the transmission system, causing the electric vehicle 1 to move. Due to the existence of the transmission ratio, there is a fixed proportional relationship between the speed of the drive motor 120 and the speed of the wheels. Based on the transmission ratio of the drive motor 120 and the corresponding motor, the speed of the wheels can be calculated. The speed of the electric vehicle 1 is directly related to the speed of the wheels. The overall vehicle speed can be calculated using the wheel speed and related wheel parameters (such as the wheel radius).

[0071] In one embodiment, the electric vehicle 1 further includes an inertial measurement unit 530, which is used to detect the acceleration (or deceleration) of the electric vehicle 1. The inertial measurement unit 530 typically consists of an accelerometer and a gyroscope. When the inertial measurement unit 530 moves with the electric vehicle 1 and experiences acceleration, the mass block in the accelerometer is subjected to an inertial force. This force causes the elastic element connected to the mass block to deform. By detecting this deformation (which can be detected by means of capacitance, piezoelectricity, etc.), the magnitude and direction of the acceleration can be measured.

[0072] In some embodiments, the drive system 100, braking system 200, vehicle controller 410, and battery controller 420 in the electric vehicle 1 can communicate and exchange signals via a communication bus. The communication bus may include a controller area network (CAN) bus, a local interconnect network (LIN) bus, a high-speed fault-tolerant network protocol (FlexRay), or other types of buses, and is not limited thereto.

[0073] In one embodiment, the drive system 100, braking system 200, vehicle controller 410, battery controller 420, and at least one sensor of the electric vehicle 1 are connected via a communication bus. This method enables the transmission of multiple signals on the same communication line, greatly improving communication efficiency and reducing a large amount of individual wiring. For example, when the motor controller 110 is connected to the communication bus, the motor controller 110 may include a communication terminal that can be connected to the communication bus. The motor controller 110 can obtain signals from the communication bus through the communication terminal. Signals from numerous sensors in the electric vehicle 1, such as the speed measurement unit 520, the inertial measurement unit 530, and the brake pedal position sensor 510, can all be transmitted to the motor controller 110 via the bus. The motor controller 110 can obtain one or more signals from the communication bus, such as vehicle speed, vehicle acceleration, and braking signals; the motor controller 110 can also upload signals to the communication bus, such as one or more signals, such as the torque value and torque direction output by the drive motor 120.

[0074] Referring to Figure 3, Figure 3 is a schematic diagram of another architecture of the electric vehicle provided in the embodiment of this application. As shown in Figure 3, the electric vehicle 1 also includes four wheels 130, namely the left front wheel LF and the right front wheel RF corresponding to the front axle 140 of the electric vehicle 1, and the left rear wheel LR and the right rear wheel RR corresponding to the rear axle 150 of the electric vehicle 1.

[0075] In one embodiment, the drive system of the electric vehicle 1 can be a centralized drive motor architecture, where two drive motors for driving the two front wheels or two drive motors for driving the two rear wheels are arranged together. As shown in FIG3, the drive system includes a drive motor 121 for driving the two front wheels and a drive motor 122 for driving the two rear wheels. A motor controller 110 is used to control one or more drive motors to output positive torque to drive the electric vehicle 1. The motor controller 110 can also be used to control one or more drive motors to output negative torque to brake the electric vehicle 1. There can be one or more motor controllers 110, and a one-to-one correspondence can exist between the motor controller 110 and the drive motors; one motor controller 110 can also correspond to multiple drive motors.

[0076] In one embodiment, the drive system can also be a wheel-side four-drive motor drive architecture, that is, the drive system includes four drive motors, each drive motor corresponds one-to-one with one of the four wheels 130, and each drive motor is located at the wheel 130 driven by each drive motor. Furthermore, there can be one or more motor controllers 110, and the motor controller 110 can correspond one-to-one with the drive motors, or one motor controller 110 can correspond to multiple drive motors.

[0077] In one embodiment, as shown in Figure 3, the braking system can be a wheel-side braking architecture, where each wheel 130 is equipped with an independent braking device 220. The braking device 220 corresponding to each wheel 130 can be directly mounted near the wheel hub. During braking, after the driver depresses the brake pedal 230, the brake controller 210 independently controls the braking device 220 corresponding to each wheel 130 to output braking force according to the braking requirements of the electric vehicle 1. This causes the brake pads in the braking device 220 corresponding to each wheel 130 to output clamping force to the brake disc, thereby braking the electric vehicle 1. There can be one or more brake controllers 210. The brake controller 210 and the braking device 220 can be in one-to-one correspondence, or one brake controller 210 can correspond to multiple braking devices 220.

[0078] In one embodiment, the braking system can also be a centralized braking architecture. After the driver presses the brake pedal 230, the brake controller 210 controls the brake device 220 to generate hydraulic pressure according to the braking requirements of the electric vehicle 1. The pressure is then transmitted centrally to the brake wheel cylinders of each wheel 130 through the brake pipeline, pushing the brake pads of each wheel 130 to output clamping force to the brake disc to brake the electric vehicle 1.

[0079] The architecture of the embodiments of this application has been described above. The following is an exemplary description of the vehicle controller in the braking control process of the electric vehicle 1. In the embodiments of this application, after the comfort braking mode is activated, the vehicle controller used to implement the above-mentioned braking control process of the electric vehicle 1 can be the vehicle controller 410, the motor controller 110, or the brake controller 210, and no limitation is made here.

[0080] In some implementations, users can pre-select to enable a comfort braking mode. This can be achieved through various methods, including: selecting the comfort braking mode in the human-vehicle interaction system; pressing a comfort braking mode button; or selecting the comfort braking mode in a terminal device connected to the electric vehicle 1 via wired or wireless means. No specific method is limited in these cases. Whether the electric vehicle 1 enters comfort braking mode during braking is determined by the user's selection. Based on the user's pre-selection, the electric vehicle 1 automatically enters comfort braking mode when its driving conditions meet the comfort braking requirements. In some embodiments, after the user selects to enable comfort braking mode, the comfort braking mode is automatically activated upon subsequent startup of the electric vehicle 1, simplifying user operation and improving the user experience.

[0081] In one embodiment, when the vehicle controller used to implement the braking control process of the electric vehicle 1 provided in the present application embodiment is a vehicle controller 410, please refer to FIG4, which is a schematic diagram of the control process of the vehicle controller 410 of the electric vehicle 1 provided in the present application embodiment.

[0082] During the braking process of electric vehicle 1, after the driver presses the brake pedal, the vehicle controller 410 obtains the brake pedal opening signal from the brake pedal position sensor 510, wherein the pedal opening signal is used to indicate the opening of the brake pedal.

[0083] In one embodiment, since the maximum permissible negative torque that the drive motor 120 can output is dynamically changing during the operation of the electric vehicle 1, the maximum permissible negative torque of the drive motor 120 is limited by the state of the drive motor 120 and the state of the power battery 300. That is, when the braking force of the drive motor 120 gradually increases, it is necessary to consider whether the energy recovery power of the drive motor 120 will exceed the charging power limit of the electric battery and whether the drive motor 120 itself can withstand it. Therefore, the vehicle controller 410 is also used to obtain the motor state signal from the motor controller 110 and the battery state signal from the battery controller 420 to determine the maximum permissible negative torque of the drive motor 120, and then determine the preset opening degree corresponding to the current brake pedal. Among them, the maximum permissible negative torque of the drive motor 120 is the maximum negative torque that the drive motor 120 can output during safe and stable operation, and the total braking force indicated by the braking signal generated by the vehicle controller 410 when the brake pedal opening degree increases to the preset opening degree is the maximum permissible braking force provided to the electric vehicle 1 when the drive motor 120 outputs the maximum permissible negative torque.

[0084] The motor status signal is used to indicate at least the peak torque and temperature of the drive motor 120. The peak torque is the maximum torque value that the drive motor 120 can output within a short period, reflecting the power performance limit of the drive motor 120. The maximum permissible negative torque of the drive motor 120 is less than or equal to the peak torque. Furthermore, since the drive motor 120 generates heat during operation, excessively high temperatures can affect its performance and lifespan. To protect the drive motor 120, its current temperature must be considered when determining the maximum permissible negative torque. When the motor temperature approaches or exceeds its maximum permissible temperature, the maximum permissible negative torque should be reduced accordingly.

[0085] The battery status signal is used to indicate at least the battery charge, battery temperature, and maximum charge / discharge power of the power battery 300. Specifically, the energy recovery power of the drive motor 120 when outputting negative torque must not exceed the maximum charging power of the power battery 300; otherwise, it will lead to overcharging of the power battery 300. Firstly, when the battery charge is high, to ensure the lifespan of the power battery 300, the energy recovery power of the drive motor 120 needs to be limited, thereby reducing the maximum permissible negative torque. When the battery charge is low, the power battery 300 may allow for higher charging power, so the energy recovery power of the drive motor 120 can be appropriately increased, increasing the maximum permissible negative torque of the drive motor 120. Furthermore, in low-temperature environments, the internal resistance of the power battery 300 will increase, leading to a decrease in its charge / discharge capacity; in this case, the maximum permissible negative torque of the drive motor 120 should be limited. Conversely, in high-temperature environments, the lifespan of the power battery 300 will be shortened; to protect the power battery 300, the maximum permissible negative torque of the drive motor 120 also needs to be appropriately reduced.

[0086] In one embodiment, if the vehicle controller 410 detects that the opening of the brake pedal has increased to a value greater than a preset opening, the vehicle controller 410 outputs a first braking control command to the motor controller 110 and a second braking control command to the brake controller 210. The first braking control command instructs the motor controller 110 to control the first braking force output by the drive motor 120, and the second braking control command instructs the brake controller 210 to control the second braking force output by the braking device 220.

[0087] The vehicle controller 410 is used to determine the total braking force of the electric vehicle 1 when braking based on the detected opening of the brake pedal. The total braking force is the sum of the first braking force indicated by the first braking control command output by the vehicle controller 410 and the second braking force indicated by the second braking control command. The vehicle controller 410 controls the total braking force to increase as the opening of the brake pedal increases. The vehicle controller 410 controls the first braking force output by the drive motor 120 to be less than or equal to the maximum permissible braking force provided when the drive motor 120 outputs the maximum permissible negative torque.

[0088] In one implementation, in a manual driving scenario, the vehicle controller 410 determines the total braking force of the electric vehicle 1 when braking based on the detected opening of the brake pedal. In an intelligent driving scenario, the vehicle controller 410 obtains the total braking force of the electric vehicle 1 when braking from the advanced driver assistance systems (ADAS) of the electric vehicle 1.

[0089] Advanced driver assistance systems (ADAS) determine the appropriate total braking force by integrating information from multiple sensors, combining vehicle dynamics models, and considering driving strategies and objectives. ADAS uses data collected from millimeter-wave radar, cameras, lidar, and wheel speed sensors to understand the vehicle's surrounding environment, the state of target objects, and its own driving status. Simultaneously, based on vehicle dynamics models, it calculates the total braking force required by braking, taking into account current vehicle speed, steering angle, and road surface adhesion coefficient.

[0090] Because the greater the first braking force output by the drive motor 120 during braking, the higher the energy recovery efficiency of the electric vehicle 1 during braking, when the vehicle controller 410 detects that the opening of the brake pedal increases to a value greater than the preset opening, it controls the first braking force output by the drive motor 120 to be the maximum allowable braking force of the drive motor 120, and controls the second braking force output by the braking device 220 to be the difference between the total braking force corresponding to the opening of the brake pedal and the maximum allowable braking force of the drive motor 120, which greatly improves the energy recovery rate of the drive motor 120 during braking, thereby reducing the overall energy consumption of the electric vehicle 1.

[0091] In this embodiment, the motor controller 110 is used to output a negative torque control signal to the drive motor 120 based on a first braking control command, controlling the drive motor 120 to output a negative torque opposite to the rotational speed of the wheels of the electric vehicle 1, so that the drive motor 120 provides a first braking force to the electric vehicle 1. The motor controller 110 is also used to feed back a torque signal and a speed signal to the vehicle controller 410, wherein the torque signal is used to indicate the actual negative torque output by the drive motor 120, and the vehicle controller 410 is used to determine the actual first braking force provided by the drive motor 120 to the electric vehicle 1 based on the actual negative torque; the speed signal is used to indicate the speed of the drive motor 120, and the vehicle controller 410 is used to determine the vehicle speed of the electric vehicle 1 based on the speed of the drive motor 120 and the transmission ratio parameter.

[0092] The brake controller 210 is used to output a braking force control signal to the braking device 220 based on a second braking control command, so that the braking device 220 outputs a second braking force to brake the four wheels of the electric vehicle 1. The brake controller 210 is also used to feed back a braking force signal to the vehicle controller 410, which indicates the actual braking force output by the braking device 220. The vehicle controller 410 is used to determine the actual second braking force provided by the braking device 220 to the electric vehicle 1 based on the actual braking force.

[0093] In one embodiment, after the driver depresses the brake pedal, when the vehicle controller 410 obtains the brake pedal opening signal from the brake pedal position sensor 510, the vehicle controller 410 also obtains an acceleration signal from the inertial measurement unit 530. The acceleration signal is used to indicate the acceleration (or deceleration) of the electric vehicle 1. Braking of the electric vehicle 1 includes emergency braking and non-emergency braking. Emergency braking is the braking process that rapidly decelerates the electric vehicle 1 to a stop; during emergency braking, the deceleration of the electric vehicle 1 is relatively large. Non-emergency braking is the braking process that slowly decelerates the electric vehicle 1 to a stop; during non-emergency braking, the deceleration of the electric vehicle 1 is relatively small. Whether the braking mode of the electric vehicle 1 is emergency braking mode or non-emergency braking mode can be determined based on the deceleration of the electric vehicle 1, the brake pedal opening, etc.

[0094] In one embodiment, if the deceleration of electric vehicle 1 during braking is greater than or equal to a preset deceleration, then the braking mode of electric vehicle 1 is an emergency braking mode. If the deceleration of electric vehicle 1 during braking is less than the preset deceleration, then the braking mode of electric vehicle 1 is a non-emergency braking mode.

[0095] In one embodiment, if the brake pedal opening is greater than or equal to the emergency braking opening during braking of the electric vehicle 1, then the braking mode of the electric vehicle 1 is the emergency braking mode. If the brake pedal opening is less than the emergency braking opening during braking of the electric vehicle 1, then the braking mode of the electric vehicle 1 is the non-emergency braking mode.

[0096] Since the braking mode of electric vehicle 1 is emergency braking mode, it is necessary to ensure that electric vehicle 1 stops moving within the shortest possible distance to avoid dangerous situations such as collisions or loss of control. Therefore, in emergency braking mode, it is necessary to ensure the braking efficiency and braking safety of electric vehicle 1. If the vehicle controller 410 determines, based on the acquired acceleration signal, that the deceleration of electric vehicle 1 is greater than or equal to a preset deceleration, the vehicle controller 410 controls the drive motor 120 to output a first braking force and controls the braking device 220 to output a second braking force. Furthermore, during braking, the first braking force output by the drive motor 120 may increase or remain unchanged; or the second braking force output by the braking device 220 may increase or remain unchanged; or both the first braking force output by the drive motor 120 and the second braking force output by the braking device 220 may increase or remain unchanged, until the speed of electric vehicle 1 decreases to zero, without any restrictions.

[0097] When the braking mode of electric vehicle 1 is non-emergency braking mode, in addition to considering the braking efficiency and safety of electric vehicle 1, the braking comfort and user driving experience of electric vehicle 1 can also be considered. If the vehicle controller 410 determines that the deceleration of electric vehicle 1 is less than the preset deceleration based on the acquired acceleration signal, the vehicle controller 410 controls the drive motor 120 to output a first braking force and controls the braking device 220 to output a second braking force. Furthermore, when the vehicle controller 410 determines that the speed of electric vehicle 1 has decreased to less than or equal to the first preset speed based on the acquired rotational speed signal, that is, when it determines that electric vehicle 1 has entered the final stage of braking, the vehicle controller 410 also controls the reduction of one of the first braking force output by the drive motor 120 and the second braking force output by the braking device 220, and controls the reduction of the other of the first and second braking forces when one of the first and second braking forces has decreased to less than or equal to the preset braking force, thereby reducing the deceleration of electric vehicle 1 during braking and thus reducing the swaying phenomenon caused by the rapid change rate of vehicle speed during braking.

[0098] In one embodiment, if the speed of electric vehicle 1 is less than a preset speed during the braking process of electric vehicle 1, or if the rotational speed of drive motor 120 is less than a preset rotational speed during the braking process of electric vehicle 1, then electric vehicle 1 enters the final braking phase.

[0099] In one embodiment, if the vehicle controller 410 detects that the opening of the brake pedal has increased to less than or equal to a preset opening, the vehicle controller 410 outputs a first braking control signal to the drive motor 120, and the motor controller 110 outputs a negative torque control signal to the drive motor 120 based on the acquired first braking control command, controlling the drive motor 120 to output a negative torque opposite to the rotational speed of the wheels of the electric vehicle 1, so that the drive motor 120 provides a first braking force to the electric vehicle 1.

[0100] Because the higher the first braking force output by the drive motor 120 during braking, the higher the energy recovery efficiency of the electric vehicle 1 during braking, when the vehicle controller 410 detects that the opening of the brake pedal increases to less than or equal to the preset opening, it controls the second braking force output by the braking device 220 to be zero, and only controls the drive motor 120 to output the first braking force to brake the four wheels of the electric vehicle 1, which can ensure the energy recovery efficiency of the electric vehicle 1 during braking, thereby reducing the overall energy consumption of the electric vehicle 1.

[0101] In one embodiment, when the vehicle controller that implements the braking control process of the electric vehicle 1 described above is a motor controller 110, please refer to FIG5, which is a schematic diagram of the control process of the motor controller 110 of the electric vehicle 1 provided in the embodiment of this application.

[0102] During the braking process of electric vehicle 1, after the driver presses the brake pedal, the motor controller 110 obtains the brake pedal opening signal from the brake pedal position sensor 510 and the acceleration signal from the inertial measurement unit 530 to determine the opening of the brake pedal and the deceleration of electric vehicle 1.

[0103] In one embodiment, the vehicle controller 410 is used to obtain a battery status signal from the battery controller 420 and transmit the battery status signal directly to the motor controller 110. The transmission means that after receiving the battery status signal, the vehicle controller 410 does not perform complex signal processing (such as modifying the signal content) but directly transmits the battery status signal to the motor controller 110.

[0104] In one embodiment, the motor controller 110 is used to directly obtain the battery status signal from the battery controller 420 in order to reduce signal transmission delay and improve signal transmission rate.

[0105] The motor controller 110 determines the maximum permissible negative torque of the drive motor 120 based on the battery status signal and the status information of the drive motor 120 obtained from the drive motor 120 and the vehicle's sensors. The maximum permissible negative torque of the drive motor 120 is the maximum negative torque that the drive motor 120 can output during safe and stable operation.

[0106] In one embodiment, if the motor controller 110 determines, based on the acquired acceleration signal, that the deceleration of the electric vehicle 1 is less than a preset deceleration, and based on the acquired pedal opening signal, determines that the opening of the brake pedal increases to a value greater than a preset opening, the motor controller 110 is used to output a negative torque control signal to the drive motor 120 and a second braking control command to the brake controller 210, wherein the negative torque control signal is used to indicate the first braking force output by the drive motor 120, and the second braking control command is used to indicate the brake controller 210 to control the second braking force output by the braking device 220.

[0107] In one embodiment, the motor controller 110 may send the second braking control command to the brake controller 210 by sending the second braking control command to the vehicle controller 410, and the vehicle controller 410 may then transmit the second braking control command to the brake controller 210.

[0108] In this embodiment, the motor controller 110 controls the drive motor 120 to output a negative torque opposite to the rotational speed of the wheels of the electric vehicle 1 based on a negative torque control signal, so that the drive motor 120 provides a first braking force to the electric vehicle 1. The motor controller 110 is also used to acquire the torque signal and speed signal fed back by the drive motor 120. The control method of the motor controller 110 over the drive motor 120 and the braking device 220 during braking can also be referred to the relevant description of the vehicle controller 410 in the embodiment provided in FIG4, which will not be repeated here.

[0109] The brake controller 210 is used to output a braking force control signal to the braking device 220 based on a second braking control command, so that the braking device 220 outputs a second braking force to brake the four wheels of the electric vehicle 1. The brake controller 210 is also used to feed back the braking force signal to the motor controller 110, or to feed back the braking force signal to the motor controller 110 through the vehicle controller 410, which is not limited here.

[0110] In one embodiment, when the vehicle controller that implements the braking control process of the electric vehicle 1 is a brake controller 210, please refer to FIG6, which is a schematic diagram of the control process of the brake controller 210 of the electric vehicle 1 provided in the embodiment of this application.

[0111] During the braking process of electric vehicle 1, after the driver presses the brake pedal, the brake controller 210 obtains the brake pedal opening signal from the brake pedal position sensor 510 and the acceleration signal from the inertial measurement unit 530 to determine the opening of the brake pedal and the deceleration of electric vehicle 1.

[0112] In one embodiment, the vehicle controller 410 is used to obtain a battery status signal from the battery controller 420 and a motor status signal from the motor controller 110, and determine the maximum permissible negative torque of the drive motor 120 based on the battery status signal and the motor status signal, and output the maximum permissible negative torque signal to the brake controller 210. The maximum permissible negative torque signal is used to indicate the maximum permissible negative torque of the drive motor 120.

[0113] In one embodiment, if the brake controller 210 determines, based on the acquired acceleration signal, that the deceleration of the electric vehicle 1 is less than a preset deceleration, and based on the acquired pedal opening signal, determines that the opening of the brake pedal increases to a value greater than a preset opening, the brake controller 210 is used to output a first brake control command to the motor controller 110 and a brake force control signal to the brake device 220, wherein the first brake control command is used to instruct the motor controller 110 to control the first braking force output by the drive motor 120, and the brake force control signal is used to instruct the brake device 220 to output a second braking force.

[0114] In one embodiment, the brake controller 210 may send the first brake control command to the motor controller 110 by sending the first brake control command to the vehicle controller 410, and the vehicle controller 410 may then transmit the first brake control command to the motor controller 110.

[0115] In this embodiment, the motor controller 110 is used to output a negative torque control signal to the drive motor 120 based on a first braking control command, controlling the drive motor 120 to output a negative torque in the opposite direction to the rotational speed of the wheels of the electric vehicle 1, so that the drive motor 120 provides a first braking force to the electric vehicle 1. The motor controller 110 is also used to feed back torque and speed signals to the brake controller 210, or, through a pass-through method of the vehicle controller 410, feed back the torque and speed signals to the brake controller 210, which is not limited here.

[0116] The brake controller 210 is used to control the braking device 220 to output a second braking force based on the braking force control signal to brake the four wheels of the electric vehicle 1. The brake controller 210 is also used to receive the braking force signal fed back by the braking device 220. The control method of the brake controller 210 over the drive motor 120 and the braking device 220 during braking can be referred to the relevant description of the vehicle controller 410 in the embodiment provided in Figure 4, and will not be repeated here.

[0117] The following, with reference to Figures 7 to 14, provides an exemplary description of how to consider multiple factors to coordinate the control of the drive motor 120 and the braking device 220 to achieve comfortable braking.

[0118] As shown in Figures 7 and 8, Figure 7 is a schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application, and Figure 8 is a schematic diagram of the scene of the braking control process of the electric vehicle 1 provided in Figure 7.

[0119] At the first moment t1 during the braking process of electric vehicle 1, after the driver depresses the brake pedal 230, the vehicle controller can obtain the pedal opening signal of the brake pedal 230 from the brake pedal position sensor 510 and the acceleration signal from the inertial measurement unit 530. If the deceleration a of electric vehicle 1 is detected to be less than the preset deceleration a1, or if the opening A of the brake pedal 230 is detected to be less than the emergency braking opening, the vehicle controller controls electric vehicle 1 to enter a non-emergency braking state, and controls the first braking force F1 output by the drive motor 120 or the second braking force F2 output by the braking device 220 to reduce the swaying of electric vehicle 1 during braking.

[0120] The vehicle controller is also used to determine the maximum permissible negative torque of the drive motor 120 based on the motor status signal of the drive motor 120 and the battery status signal of the power battery 300, so as to determine the preset opening A1 of the brake pedal 230 during braking. That is, when the opening A of the brake pedal 230 is the preset opening A1, the total braking force F0 indicated by the brake pedal 230 is the maximum permissible braking force Fmax provided to the electric vehicle 1 when the drive motor 120 outputs the maximum permissible negative torque.

[0121] At the first moment t1, if the vehicle controller detects that the opening A of the brake pedal 230 has increased to a value greater than the preset opening A1, the vehicle controller controls the drive motor 120 to output the first braking force F1 and controls the braking device 220 to output the second braking force F2.

[0122] In one embodiment, at the first moment t1 during the braking process of electric vehicle 1, when the opening A of brake pedal 230 is greater than the preset opening A1, the vehicle controller controls the first braking force F1 output by drive motor 120 to be the maximum permissible braking force Fmax of drive motor 120. Since the maximum permissible negative torque of drive motor 120 is the maximum negative torque that drive motor 120 can output during safe and stable operation, if the first braking force F1 output by drive motor 120 is greater than the maximum permissible braking force Fmax provided to electric vehicle 1 when drive motor 120 outputs the maximum permissible negative torque, it may cause overcharging of power battery 300 or affect the performance and lifespan of drive motor 120.

[0123] At the first moment t1, if the vehicle controller detects that the opening A of the brake pedal 230 is less than or equal to the preset opening A1, the vehicle controller controls the first braking force F1 output by the drive motor 120 to increase as the opening A of the brake pedal 230 increases; if the vehicle controller detects that the opening A of the brake pedal 230 is greater than the preset opening A1, and the first braking force F1 output by the drive motor 120 is the maximum allowable braking force Fmax of the drive motor 120, the vehicle controller controls the first braking force F1 output by the drive motor 120 not to increase as the opening A of the brake pedal 230 increases, and controls the second braking force F2 output by the braking device 220 to increase as the opening A of the brake pedal 230 increases.

[0124] In one embodiment, as shown in Figure 7, at a first time t1, the vehicle controller determines the vehicle speed v of electric vehicle 1 based on the rotational speed signal of electric vehicle 1. If the vehicle speed v of electric vehicle 1 is detected to be greater than a first preset speed v1, it is determined that electric vehicle 1 has not entered the final stage of braking. To ensure the braking efficiency of electric vehicle 1 during braking, the vehicle controller controls the first braking force F1 and the second braking force F2 to remain constant, so that the deceleration a of electric vehicle 1 remains constant for a period of time. For example, the first preset speed v1 is 8 km / h.

[0125] At the second time t2 after the first time t1, if the vehicle controller detects that the speed v of electric vehicle 1 decreases to less than or equal to the first preset speed v1, it determines that electric vehicle 1 has entered the final stage of braking. The vehicle controller controls the total braking force F0 of electric vehicle 1 to decrease, so as to reduce the deceleration a of electric vehicle 1, thereby reducing the swaying phenomenon caused by the rapid change rate of speed v of electric vehicle 1 at the final stage of braking.

[0126] At the second moment t2, the vehicle controller controls the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to reduce one of them, so as to reduce the total braking force F0 of the electric vehicle 1.

[0127] At the third time t3 after the second time t2, when the vehicle controller controls one of the first braking force F1 and the second braking force F2 to decrease to less than or equal to the preset braking force F3, the vehicle controller controls the other of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to decrease.

[0128] In one embodiment, when the preset braking force F3 is greater than zero, and one of the first braking force F1 and the second braking force F2 decreases to less than or equal to the preset braking force F3, the vehicle controller controls the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to decrease simultaneously.

[0129] In one embodiment, when one of the first braking force F1 and the second braking force F2 is reduced to zero, the vehicle controller controls the other of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to decrease.

[0130] When the drive motor 120 generates braking force, the kinetic energy of the drive system 100 is converted into electrical energy. This electrical energy is fed back to the power battery 300 for storage through the circuit between the drive motor 120 and the power battery 300, realizing the energy recovery of part of the kinetic energy of the electric vehicle 1 during braking. Therefore, the greater the first braking force F1 output by the drive motor 120 during braking, that is, the higher the proportion of the first braking force F1 in the total braking force F0, the higher the energy recovery efficiency of the electric vehicle 1 during braking.

[0131] As shown in Figure 7, in one embodiment, at the first moment t1, if the opening A of the brake pedal 230 increases to a value greater than the preset opening A1, the vehicle controller determines the total braking force F0 of the electric vehicle 1 based on the opening A of the brake pedal 230, controls the first braking force F1 output by the drive motor 120 to be the maximum permissible braking force Fmax of the drive motor 120, and controls the second braking force F2 output by the braking device 220 to be the difference between the total braking force F0 and the maximum permissible braking force Fmax of the drive motor 120.

[0132] At the second moment t2, the speed v of electric vehicle 1 decreases to less than or equal to the first preset speed v1. During the process of reducing the total braking force F0 of electric vehicle 1, in order to ensure that the first braking force F1 output by drive motor 120 accounts for a certain proportion of the total braking force F0, the vehicle controller controls the second braking force F2 output by braking device 220 to decrease first, and controls the first braking force F1 output by drive motor 120 to remain unchanged.

[0133] At the third time t3 after the second time t2, if the second braking force F2 output by the braking device 220 decreases to zero, the vehicle controller controls the first braking force F1 output by the drive motor 120 to decrease until the first braking force F1 decreases to zero.

[0134] Between the second time point t2 and the third time point t3, the greater the speed v of electric vehicle 1, the smaller the rate of decrease k of controlling one of the first braking force F1 and the second braking force F2.

[0135] In one embodiment, after the third time t3, the sum of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220, controlled by the vehicle controller, is simultaneously reduced to zero along with the vehicle speed v of the electric vehicle 1. When the electric vehicle 1 brakes, its speed gradually decreases, and the vehicle body maintains a forward motion tendency due to inertia. The braking force and vehicle speed v working together to reduce to zero helps the electric vehicle 1 smoothly overcome inertia during braking, avoiding swaying caused by the mismatch between inertia and braking force. Furthermore, the suspension system of the electric vehicle 1 plays a buffering and supporting role during braking. Sudden changes in braking force can cause the suspension system to withstand significant impact forces. The coordinated reduction of the braking force and vehicle speed v to zero ensures that the suspension system of the electric vehicle 1 always operates in a relatively stable state, thereby further reducing the swaying of the electric vehicle 1 during braking.

[0136] After the second time t2, the vehicle controller controls the first braking force F1 and / or the second braking force F2 to decrease until the total braking force F0 of the electric vehicle 1 and the vehicle speed v of the electric vehicle 1 decrease to zero simultaneously. During this process, the rate of decrease k of the total braking force F0 of the electric vehicle 1 remains unchanged.

[0137] In one embodiment, the rate of decrease k of the total braking force F0 can be calculated as follows:

[0138] Using the acceleration formula: a = ak + kt. Where, ak is the deceleration a of electric vehicle 1 at the moment when the total braking force F0 begins to decrease, Fk is the total braking force F0 of electric vehicle 1 at the moment when the total braking force F0 begins to decrease, and m is the mass of electric vehicle 1.

[0139] Using the velocity formula: Finally obtained Where vk is the speed v of electric vehicle 1 at the moment when the total braking force F0 begins to decrease.

[0140] In one embodiment, when the total braking force F0 begins to decrease at the second time t2, the greater the total braking force F0 of the electric vehicle 1 at the second time t2, the greater the rate of decrease k of the total braking force F0; or, the greater the vehicle speed v of the electric vehicle 1 at the second time t2, the smaller the rate of decrease k of the total braking force F0.

[0141] In one embodiment, after the second time t2, the rate of decrease k of the total braking force F0 of electric vehicle 1 remains constant, so that the total braking force F0 decreases to zero while the speed v of electric vehicle 1 decreases to zero. For example, after the second time t2, the vehicle controller controls the second braking force F2 to decrease at a certain rate k until it decreases to zero at the third time t3. After the third time t3, the vehicle controller controls the first braking force F1 to decrease at the same rate k until the first braking force F1 decreases to zero at the fourth time t4 and the speed v of electric vehicle 1 decreases to zero. In this way, the deceleration a of electric vehicle 1 can decrease uniformly during braking, thereby reducing the abruptness of electric vehicle 1 during braking, reducing the swaying phenomenon of electric vehicle 1 during braking, achieving comfortable braking of electric vehicle 1, and improving the user's driving experience.

[0142] In one embodiment, when the electric vehicle 1 is in a low-speed, stop-and-go condition, the vehicle speed v of the electric vehicle 1 changes frequently and with small amplitude. Since the braking control precision of the drive motor 120 is higher than that of the braking device 220, during the process of reducing the total braking force F0, the second braking force F2 is reduced, and then the first braking force F1 is reduced. This effectively utilizes the high braking precision of the drive motor 120 during the process of reducing the deceleration a of the electric vehicle 1 at the end of the braking process. This allows the electric vehicle 1 to accurately provide appropriate braking force in a timely manner according to the vehicle speed v and the driver's intention, reducing the swaying phenomenon of the electric vehicle 1 during the braking process and achieving comfortable braking of the electric vehicle 1.

[0143] At the fourth time t4 after the third time t3, the speed v of electric vehicle 1 decreases to zero. The vehicle controller is also used to immediately control the increase of the second braking force F2 output by the braking device 220 after electric vehicle 1 stops, so as to avoid vehicle movement caused by the gap between the transmission system and components, or the vehicle slippage caused by the component force of gravity along the slope due to the slope, thereby ensuring that electric vehicle 1 is stationary.

[0144] In one embodiment, at the fourth time t4, the vehicle controller controls the second braking force F2 output by the braking device 220 to increase to a level greater than the braking force output by the braking device 220 at the first time t1. Furthermore, at the fifth time t5 after the fourth time t4, the opening A of the brake pedal 230 decreases to zero, and the second braking force F2 output by the braking device 220 decreases to zero. Thus, by increasing the braking force at the moment of stopping, it is ensured that the electric vehicle 1 remains stable and stationary after stopping, without any back-and-forth swaying.

[0145] In this embodiment, during the braking process of electric vehicle 1, when the opening A of brake pedal 230 increases to a value greater than the preset opening A1, since the total braking force F0 indicated by brake pedal 230 when the opening A of brake pedal 230 is the preset opening A1 is the maximum permissible braking force Fmax provided to electric vehicle 1 when drive motor 120 outputs the maximum permissible negative torque, the first braking force F1 output by drive motor 120 is controlled to be the maximum permissible negative torque, and the second braking force F2 output by brake motor is controlled to be the difference between total braking force F0 and first braking force F1. At the same time, during the process of controlling the total braking force F0 to decrease, the second braking force F2 is controlled to decrease first and then the first braking force F1 is controlled to decrease, ensuring that the proportion of the first braking force F1 output by drive motor 120 in the total braking force F0 is maintained, thereby improving the overall vehicle range. Furthermore, by coordinating the control of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220, the deceleration a and vehicle speed v of the electric vehicle 1 can be stably reduced to zero during braking. This reduces the swaying phenomenon caused by the rapid change of vehicle speed v during braking, achieving comfortable braking of the electric vehicle 1 and improving the user's driving experience.

[0146] As shown in Figures 9 and 10, Figure 9 is another schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application, and Figure 10 is a schematic diagram of the scenario of the braking control process of the electric vehicle 1 provided in Figure 9.

[0147] During the braking process of electric vehicle 1, the vehicle controller is used to determine the maximum permissible negative torque of drive motor 120 based on the motor status signal of drive motor 120 and the battery status signal of power battery 300, so as to determine the preset opening degree A1 of brake pedal 230 during the braking process.

[0148] At the first moment t1 during the braking process of electric vehicle 1, after the driver presses the brake pedal 230, if the vehicle controller determines that the opening A of the brake pedal 230 has increased to a level greater than the preset opening A1 based on the pedal opening signal of the brake pedal 230 obtained from the brake pedal position sensor 510, and determines that the deceleration a of electric vehicle 1 is less than the preset deceleration a1 based on the acceleration signal obtained from the inertial measurement unit 530, the vehicle controller controls the drive motor 120 to output the first braking force F1 and controls the braking device 220 to output the second braking force F2.

[0149] In one embodiment, as shown in FIG9, at a first time t1, if the opening A of the brake pedal 230 increases to a value greater than a preset opening A1, the vehicle controller determines the total braking force F0 of the electric vehicle 1 based on the opening A of the brake pedal 230, controls the first braking force F1 output by the drive motor 120 to be the maximum permissible braking force Fmax of the drive motor 120, and controls the second braking force F2 output by the braking device 220 to be the difference between the total braking force F0 and the maximum permissible braking force Fmax of the drive motor 120.

[0150] At the first moment t1, the vehicle controller is also used to determine the vehicle speed v of the electric vehicle 1 based on the rotation speed signal of the electric vehicle 1. If the vehicle speed v of the electric vehicle 1 is detected to be less than or equal to the first preset vehicle speed v1, it is determined that the electric vehicle 1 is in the final stage of braking. The vehicle controller controls the total braking force F0 of the electric vehicle 1 to decrease, so as to reduce the deceleration a of the electric vehicle 1.

[0151] At a first time t1, after the vehicle controller controls the drive motor 120 to output a first braking force F1 and the braking device 220 to output a second braking force F2, it controls one of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to decrease, thereby reducing the total braking force F0 of the electric vehicle 1. At a second time t2 after the first time t1, when the vehicle controller controls one of the first braking force F1 and the second braking force F2 to decrease to less than or equal to a preset braking force F3, the vehicle controller controls the other of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to decrease.

[0152] As the first braking force F1 output by the drive motor 120 increases during braking, i.e., the higher the proportion of the first braking force F1 in the total braking force F0, the higher the energy recovery efficiency of the electric vehicle 1 during braking. As shown in Figure 9, at the first moment t1, the vehicle controller controls the second braking force F2 output by the braking device 220 to decrease first, while keeping the first braking force F1 output by the drive motor 120 unchanged. At the second moment t2 after the first moment t1, if the second braking force F2 output by the braking device 220 decreases to zero, the vehicle controller controls the first braking force F1 output by the drive motor 120 to decrease until the first braking force F1 decreases to zero.

[0153] In one embodiment, after the second time t2, the vehicle controller controls the sum of the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220 to simultaneously reduce the vehicle speed v of the electric vehicle 1 to zero. By controlling the total braking force F0 of the electric vehicle 1 to decrease to zero in tandem with the vehicle speed v, the swaying of the electric vehicle 1 during braking or due to inertia and mismatch of braking force can be avoided, and the suspension system of the electric vehicle 1 can always operate in a relatively stable state, thereby further reducing the swaying of the electric vehicle 1 during braking.

[0154] At the third time t3, following the second time t2, the first braking force F1 output by the drive motor 120 decreases to zero, meaning the total braking force F0 of the electric vehicle 1 decreases to zero, and the vehicle speed v of the electric vehicle 1 decreases to zero. The vehicle controller also controls the increase of the second braking force F2 output by the braking device 220 immediately after the electric vehicle 1 stops. Furthermore, at the fourth time t4, following the third time t3, the opening A of the brake pedal 230 decreases to zero, controlling the second braking force F2 output by the braking device 220 to decrease to zero. Thus, by increasing the braking force at the moment of stopping, it ensures that the electric vehicle 1 remains stable and stationary after stopping, without any back-and-forth swaying.

[0155] As shown in Figures 11 and 12, Figure 11 is another schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application; Figure 12 is a schematic diagram of the scenario of the braking control process of the electric vehicle 1 provided in Figure 11.

[0156] During the braking process of electric vehicle 1, the vehicle controller is used to determine the maximum permissible negative torque of drive motor 120 based on the motor status signal of drive motor 120 and the battery status signal of power battery 300, so as to determine the preset opening degree A1 of brake pedal 230 during the braking process.

[0157] At the first moment t1 during the braking process of electric vehicle 1, after the driver depresses the brake pedal 230, if the vehicle controller determines that the opening A of the brake pedal 230 has increased to less than or equal to a preset opening A1 based on the pedal opening signal of the brake pedal 230 obtained from the brake pedal position sensor 510, and determines that the deceleration a of electric vehicle 1 is less than the preset deceleration a1 based on the acceleration signal obtained from the inertial measurement unit 530, the vehicle controller controls the drive motor 120 to output a first braking force F1. The first braking force F1 output by the drive motor 120 controlled by the vehicle controller increases as the opening A of the brake pedal 230 increases.

[0158] When the drive motor 120 generates braking force, the kinetic energy of the drive system 100 is converted into electrical energy for storage. When the opening degree A of the brake pedal 230 is less than or equal to the preset opening degree A1, the vehicle controller determines that the total braking force F0 of the electric vehicle 1 is less than or equal to the maximum allowable braking force Fmax of the drive motor 120. During the braking process, the vehicle controller controls the drive motor 120 to output the first braking force F1 and controls the second braking force F2 output by the braking device 220 to be zero, so as to ensure the energy recovery efficiency of the electric vehicle 1 during the braking process.

[0159] In one embodiment, as shown in FIG11, at a first time t1, the vehicle controller determines the vehicle speed v of electric vehicle 1 based on the rotational speed signal of electric vehicle 1. If the vehicle speed v of electric vehicle 1 is detected to be greater than a second preset speed v2, it is determined that electric vehicle 1 has not entered the final stage of braking. To ensure the braking efficiency of electric vehicle 1 during the braking process, the vehicle controller controls the first braking force F1 output by the drive motor 120 to remain constant, so that the deceleration a of electric vehicle 1 remains constant for a period of time. For example, the second preset speed v2 is 4 km / h.

[0160] In one embodiment, both the first preset vehicle speed v1 and the second preset vehicle speed v2 are preset speeds determined by the vehicle controller for the electric vehicle 1 to enter the final stage of braking. When the vehicle speed v of the electric vehicle 1 is lower than the preset speed, the vehicle controller controls the total braking force F0 output by the drive motor 120 to decrease, thereby reducing the swaying phenomenon caused by the rapid change rate of vehicle speed v during the final stage of braking. To reduce the swaying phenomenon of the electric vehicle 1 during braking and to ensure braking efficiency, when the total braking force F0 output by the electric vehicle 1 is different (i.e., the electric vehicle 1 simultaneously outputs the first braking force F1 and the second braking force F2), the threshold for the vehicle controller to determine the preset speed for the electric vehicle 1 to enter the final stage of braking is different from the case where the electric vehicle 1 only outputs the first braking force F1. The larger the total braking force F0 of the electric vehicle 1, the larger the preset speed for the electric vehicle 1 to enter the final stage of braking.

[0161] At the second time t2 after the first time t1, if the vehicle controller detects that the speed v of electric vehicle 1 decreases to less than or equal to the second preset speed v2, it determines that electric vehicle 1 has entered the final stage of braking. The vehicle controller controls the total braking force F0 of electric vehicle 1 to decrease, that is, controls the first braking force F1 output by drive motor 120 to decrease, so as to reduce the deceleration a of electric vehicle 1, thereby reducing the swaying phenomenon caused by the rapid change rate of speed v of electric vehicle 1 at the final stage of braking.

[0162] In one embodiment, after the second time t2, the vehicle controller controls the first braking force F1 output by the drive motor 120 and the vehicle speed v of the electric vehicle 1 to decrease simultaneously to zero. By controlling the total braking force F0 of the electric vehicle 1 to decrease to zero in tandem with the vehicle speed v, the swaying of the electric vehicle 1 during braking or due to inertia and mismatch of braking force can be avoided, and the suspension system of the electric vehicle 1 can always operate in a relatively stable state, thereby further reducing the swaying of the electric vehicle 1 during braking.

[0163] At the third time t3, following the second time t2, the first braking force F1 output by the drive motor 120 decreases to zero, meaning the total braking force F0 of the electric vehicle 1 decreases to zero, and the vehicle speed v of the electric vehicle 1 decreases to zero. The vehicle controller also controls the increase of the second braking force F2 output by the braking device 220 immediately after the electric vehicle 1 stops. Furthermore, at the fourth time t4, following the third time t3, the opening A of the brake pedal 230 decreases to zero, controlling the second braking force F2 output by the braking device 220 to decrease to zero. Thus, by increasing the braking force at the moment of stopping, it ensures that the electric vehicle 1 remains stable and stationary after stopping, without any back-and-forth swaying.

[0164] In this embodiment, during the braking process of electric vehicle 1, when the opening A of brake pedal 230 increases to less than or equal to the preset opening A1, since the total braking force F0 indicated by brake pedal 230 when the opening A of brake pedal 230 is the preset opening A1 is the maximum permissible braking force Fmax provided to electric vehicle 1 when drive motor 120 outputs the maximum permissible negative torque, the vehicle controller only controls drive motor 120 to output the first braking force F1, ensuring the energy recovery efficiency of electric vehicle 1 during braking and improving the overall vehicle range. Simultaneously, since the braking control precision of drive motor 120 is higher than that of braking device 220, in the process of controlling the reduction of the first braking force F1 to reduce the deceleration a of electric vehicle 1, the high braking precision of drive motor 120 is effectively utilized, reducing the swaying phenomenon of electric vehicle 1 during braking and achieving comfortable braking of electric vehicle 1.

[0165] As shown in Figures 13 and 14, Figure 13 is another schematic diagram of the braking control process of the electric vehicle 1 provided in the embodiment of this application, and Figure 14 is a schematic diagram of the scenario of the braking control process of the electric vehicle 1 provided in Figure 13.

[0166] During the braking process of electric vehicle 1, the vehicle controller is used to determine the maximum permissible negative torque of drive motor 120 based on the motor status signal of drive motor 120 and the battery status signal of power battery 300, so as to determine the preset opening degree A1 of brake pedal 230 during the braking process.

[0167] At the first moment t1 during the braking process of electric vehicle 1, after the driver depresses the brake pedal 230, if the vehicle controller determines that the opening A of the brake pedal 230 has increased to less than or equal to a preset opening A1 based on the pedal opening signal of the brake pedal 230 obtained from the brake pedal position sensor 510, and determines that the deceleration a of electric vehicle 1 is less than the preset deceleration a1 based on the acceleration signal obtained from the inertial measurement unit 530, the vehicle controller controls the drive motor 120 to output a first braking force F1. The first braking force F1 output by the drive motor 120 controlled by the vehicle controller increases as the opening A of the brake pedal 230 increases.

[0168] In one embodiment, as shown in FIG13, at a first time t1, the vehicle controller determines the vehicle speed v of the electric vehicle 1 based on the rotation speed signal of the electric vehicle 1. If the vehicle speed v of the electric vehicle 1 is detected to be less than the second preset vehicle speed v2, it is determined that the electric vehicle 1 has entered the final stage of braking. The vehicle controller controls the total braking force F0 of the electric vehicle 1 to decrease, that is, controls the first braking force F1 output by the drive motor 120 to decrease, so as to reduce the deceleration a of the electric vehicle 1, thereby reducing the shaking phenomenon caused by the rapid change rate of vehicle speed v in the final stage of braking.

[0169] In one embodiment, after the first moment t1, the vehicle controller controls the first braking force F1 output by the drive motor 120 and the vehicle speed v of the electric vehicle 1 to decrease simultaneously to zero. By controlling the total braking force F0 of the electric vehicle 1 to decrease to zero in tandem with the vehicle speed v, the swaying of the electric vehicle 1 during braking or due to inertia and mismatch of braking force can be avoided, and the suspension system of the electric vehicle 1 can always operate in a relatively stable state, thereby further reducing the swaying of the electric vehicle 1 during braking.

[0170] At the second time t2, following the first time t1, the first braking force F1 output by the drive motor 120 decreases to zero, meaning the total braking force F0 of the electric vehicle 1 decreases to zero, and the vehicle speed v of the electric vehicle 1 decreases to zero. The vehicle controller also controls the increase of the second braking force F2 output by the braking device 220 immediately after the electric vehicle 1 stops. Furthermore, at the third time t3, following the second time t2, the opening A of the brake pedal 230 decreases to zero, controlling the decrease of the second braking force F2 output by the braking device 220 to zero. Thus, by increasing the braking force at the moment of stopping, it ensures that the electric vehicle 1 remains stable and stationary after stopping, without any back-and-forth swaying.

[0171] In this embodiment, during the braking process of electric vehicle 1, when the opening A of brake pedal 230 increases to less than or equal to the preset opening A1, only the drive motor 120 is controlled to output the first braking force F1 and the first braking force F1 is adjusted. This not only effectively utilizes the energy recovery performance of drive motor 120 and improves the overall vehicle range, but also effectively utilizes the high braking precision of drive motor 120, reducing the shaking phenomenon of electric vehicle 1 during braking, achieving comfortable braking of electric vehicle 1, and thus improving the user's driving experience.

[0172] As shown in Figures 15 and 16, Figure 15 is a schematic diagram of the operation of the electric vehicle 1 in emergency braking mode according to the embodiment of this application, and Figure 16 is a schematic diagram of the braking control process of the electric vehicle 1 shown in Figure 15.

[0173] During the braking process of electric vehicle 1, after the driver depresses the brake pedal 230, the vehicle controller can obtain the pedal opening signal of the brake pedal 230 from the brake pedal position sensor 510 and the acceleration signal from the inertial measurement unit 530. When the deceleration a of electric vehicle 1 is detected to be greater than or equal to the preset deceleration a1, or when the opening A of the brake pedal 230 is detected to be greater than or equal to the emergency braking opening A2, the vehicle controller controls electric vehicle 1 to enter an emergency braking state, and controls the first braking force F1 output by the drive motor 120 or the second braking force F2 output by the braking device 220 to reduce the swaying of electric vehicle 1 during braking.

[0174] At the first moment t1, if the vehicle controller detects that the opening A of the brake pedal 230 increases to be greater than or equal to the emergency braking opening A2, or the deceleration a of the electric vehicle 1 is greater than or equal to the preset deceleration a1, the vehicle controller controls the first braking force F1 output by the drive motor 120 and the second braking force F2 output by the braking device 220.

[0175] After the first moment t1, during the emergency braking of electric vehicle 1, the vehicle controller controls the first braking force F1 output by drive motor 120 to increase or remain constant, and the first braking force F1 of drive motor 120 is less than or equal to the maximum permissible braking force Fmax, until the vehicle speed v of electric vehicle 1 decreases to zero. During braking, the vehicle controller controls the first braking force F1 output by drive motor 120 to be less than or equal to the maximum permissible braking force Fmax.

[0176] In one embodiment, during emergency braking of the electric vehicle 1, the vehicle controller controls the first braking force F1 output by the drive motor 120 and / or the second braking force F2 output by the braking device 220 to increase or remain unchanged until the vehicle speed v of the electric vehicle 1 decreases to zero. When the electric vehicle 1 is in emergency braking mode, to ensure the braking efficiency and safety of the electric vehicle 1, the total braking force F0 output by the electric vehicle 1 is no longer controlled to decrease, so that the total braking force F0 of the electric vehicle 1 during braking always remains at the braking value indicated by the brake controller 210. That is, in emergency braking mode, the braking scheme provided in this application for reducing the swaying phenomenon of the electric vehicle 1 during braking will not take effect.

[0177] At the second time t2, following the first time t1, the total braking force F0 of electric vehicle 1 remains unchanged, and the speed v of electric vehicle 1 decreases to zero. The vehicle controller also controls the second braking force F2 output by the braking device 220 to increase immediately after electric vehicle 1 stops. Furthermore, at the third time t3, following the second time t2, the opening A of the brake pedal 230 decreases to zero, and the second braking force F2 output by the braking device 220 decreases to zero. Thus, by increasing the braking force at the moment of stopping, it is ensured that electric vehicle 1 remains stable and stationary after stopping, without any back-and-forth swaying.

[0178] In this embodiment, since the electric vehicle 1 needs to stop moving within the shortest possible distance in the emergency braking mode to avoid dangerous situations such as collision or loss of control of the electric vehicle 1, the vehicle controller will not control the first braking force F1 output by the drive motor 120 and / or the second braking force F2 output by the braking device 220 to decrease at this time, thereby ensuring the braking efficiency and braking safety of the electric vehicle 1.

[0179] It should be understood that the numerical changes in Figures 7 to 16 are merely illustrative and do not represent specific values, and may contain certain deviations. The trends are only used to illustrate the method and flow of the scheme in this application, and do not limit the deviations in the actual control process.

[0180] In the embodiments provided in this application, each functional module can be integrated into one device, or each module can exist physically separately, or two or more modules can be integrated into one device.

[0181] As shown in Figure 17, Figure 17 is a schematic flowchart of a comfort braking control method for an electric vehicle provided in an embodiment of this application. This control method is used to control the drive motor and braking device of the electric vehicle during braking to reduce the swaying of the electric vehicle during braking, and includes the following steps:

[0182] S1. Determine whether the electric vehicle is in comfort braking mode.

[0183] If it is determined that the electric vehicle is in comfort braking mode, proceed to step S2; otherwise, terminate comfort braking control.

[0184] S2. Determine whether the electric vehicle is in forward gear.

[0185] If it is determined that the electric vehicle is in forward gear, proceed to step S3; otherwise, terminate comfort braking control.

[0186] S3. Determine whether the deceleration of the electric vehicle is less than the preset deceleration.

[0187] If it is determined that the electric vehicle is at a deceleration less than the preset value, then the electric vehicle is determined to be in non-emergency braking mode, and step S4 is executed; otherwise, the electric vehicle is determined to be in emergency braking mode, and comfort braking control is terminated.

[0188] S4. Determine whether the brake pedal opening is greater than the preset opening.

[0189] If it is determined that the opening degree of the brake pedal is greater than the preset opening degree, then it is determined that the total braking force indicated by the brake pedal is greater than the maximum allowable braking force provided to the electric vehicle when the drive motor outputs the maximum allowable negative torque, and step S5 is executed; otherwise, step S10 is executed.

[0190] S5. Control the drive motor to output the first braking force and control the braking device to output the second braking force. The first braking force is the maximum permissible braking force of the drive motor.

[0191] S6. Determine whether the vehicle speed is less than or equal to the first preset vehicle speed.

[0192] If the vehicle speed is determined to be less than or equal to the first preset vehicle speed, then the electric vehicle is determined to be entering the final stage of braking, the total braking force is reduced, and step S7 is executed.

[0193] S7. Control the second braking force to reduce to zero.

[0194] S8: Control the first braking force and vehicle speed to decrease to zero simultaneously.

[0195] S9. Control the brake pedal to output a second braking force until the brake pedal opening is reduced to zero.

[0196] S10, control the drive motor to output the first braking force.

[0197] If it is determined that the opening of the brake pedal is less than or equal to the preset opening, then it is determined that the total braking force indicated by the brake pedal is less than or equal to the maximum permissible braking force provided to the electric vehicle when the drive motor outputs the maximum permissible negative torque, and only the drive motor is controlled to output the first braking force.

[0198] S11. Determine whether the vehicle speed is less than or equal to the second preset vehicle speed.

[0199] If the vehicle speed is determined to be less than or equal to the second preset vehicle speed, then the electric vehicle is determined to be entering the final stage of braking, the total braking force is reduced, and step S12 is executed.

[0200] S12, control the first braking force and vehicle speed to decrease to zero simultaneously.

[0201] In another embodiment of this application, a vehicle controller for an electric vehicle is also provided, which is used to control the electric vehicle to achieve a comfort braking function.

[0202] In another embodiment of this application, an electric vehicle is also provided, which includes a drive motor, a braking device, and a vehicle controller provided in the above embodiments. The vehicle controller is used to control the drive motor and the braking device to realize the comfort braking function of the electric vehicle.

[0203] It is understood that all relevant content of each step involved in the above method embodiments can be referenced in the above vehicle controller embodiments and the electric vehicle embodiments, and the embodiments of this application will not be repeated here.

[0204] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for comfort braking of an electric vehicle, characterized in that, The control method is used to control the first braking force output by the drive motor of the electric vehicle or the second braking force output by the braking device during braking when the deceleration of the electric vehicle is less than a preset deceleration, so as to reduce the swaying of the electric vehicle during braking. The control method includes: At the first moment during the braking process of the electric vehicle, the opening of the brake pedal is increased to a value greater than the preset opening, and the drive motor is controlled to output the first braking force and the braking device is controlled to output the second braking force. At a second moment after the first moment, the speed of the electric vehicle is reduced to less than or equal to a first preset speed, and one of the first braking force and the second braking force is reduced. At a third moment following the second moment, control the reduction of the other of the first braking force and the second braking force.

2. The control method according to claim 1, characterized in that, The control method specifically includes: At a third moment following the second moment, one of the first braking force and the second braking force is reduced to less than or equal to a preset braking force, and the other of the first braking force and the second braking force is controlled to decrease.

3. The control method according to claim 1 or 2, characterized in that, The control method specifically includes: At a second moment following the first moment, the second braking force is reduced. At a third moment following the second moment, the first braking force is reduced.

4. The control method according to any one of claims 1 to 3, characterized in that, The control method further includes: After the third moment, the sum of the first braking force and the second braking force is controlled to decrease to zero simultaneously with the speed of the electric vehicle.

5. The control method according to any one of claims 1 to 3, characterized in that, The control method further includes: Between the second and third time points, the greater the speed of the electric vehicle, the smaller the rate of reduction of either the first or the second braking force.

6. The control method according to claim 1, characterized in that, The control method specifically includes: At the first moment during the braking process of the electric vehicle, the opening degree of the brake pedal is less than or equal to the preset opening degree, and the first braking force is controlled to increase as the opening degree of the brake pedal increases; At the first moment during the braking process of the electric vehicle, the opening degree of the brake pedal is greater than the preset opening degree, so that the first braking force does not increase as the opening degree of the brake pedal increases.

7. The control method according to any one of claims 1 to 6, characterized in that, The control method further includes: At the fourth moment following the third moment, the vehicle speed of the electric vehicle decreases to zero, and the second braking force output by the braking device increases.

8. The control method according to claim 7, characterized in that, The control method specifically includes: At the fourth moment, the second braking force output by the braking device is increased to be greater than the braking force output by the braking device at the first moment.

9. The control method according to claim 7 or 8, characterized in that, The control method further includes: At the fifth moment following the fourth moment, the opening of the brake pedal is reduced to zero, and the second braking force output by the braking device is reduced to zero.

10. The control method according to claim 1, characterized in that, The control method further includes: During the braking process where the deceleration of the electric vehicle is greater than or equal to the preset deceleration, the first braking force output by the drive motor is increased or kept constant until the speed of the electric vehicle decreases to zero.

11. A control method for comfort braking of an electric vehicle, characterized in that, The control method is used to control the first braking force output by the drive motor of the electric vehicle during braking when the deceleration of the electric vehicle is less than a preset deceleration, so as to reduce the swaying of the electric vehicle during braking. The control method includes: At the first moment during the braking process of the electric vehicle, the opening of the brake pedal is increased to be less than or equal to a preset opening, and the drive motor is controlled to output the first braking force. At a second moment after the first moment, the speed of the electric vehicle is reduced to less than or equal to a second preset speed, and the first braking force is reduced.

12. The control method according to claim 11, characterized in that, The control method specifically includes: After the second moment, the first braking force and the speed of the electric vehicle are simultaneously reduced to zero.

13. A vehicle controller for comfort braking control of electric vehicles, characterized in that, The vehicle controller is used to implement the control method as described in any one of claims 1 to 10, wherein the vehicle controller is used to control the first braking force output by the drive motor of the electric vehicle or control the second braking force output by the braking device during the braking process when the deceleration of the electric vehicle is less than a preset deceleration, and the vehicle controller is specifically used for: During the braking process of the electric vehicle, in response to the brake pedal opening increasing to a value greater than a preset opening, the drive motor is controlled to output the first braking force and the braking device is controlled to output the second braking force to brake the four wheels of the electric vehicle. In response to the electric vehicle's speed decreasing to less than or equal to a first preset speed, the first braking force and the second braking force are reduced, and then the other of the first braking force and the second braking force are reduced.

14. A vehicle controller for comfort braking control of electric vehicles, characterized in that, The vehicle controller is used to implement the control method as described in any one of claims 11 to 12, wherein the vehicle controller is used to control the first braking force output by the drive motor of the electric vehicle during braking when the deceleration of the electric vehicle is less than a preset deceleration, and the vehicle controller is specifically used for: During the braking process of the electric vehicle, in response to the brake pedal opening increasing to less than or equal to a preset opening, the drive motor is controlled to output the first braking force to brake the four wheels of the electric vehicle. In response to the electric vehicle's speed decreasing to less than or equal to a second preset speed, the first braking force is controlled to decrease.

15. An electric vehicle, characterized in that, The electric vehicle includes a drive motor, a braking device, and a vehicle controller as described in any one of claims 13 to 14, the vehicle controller being used to control the drive motor and the braking device to perform the control method as described in any one of claims 1 to 12.

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