Vehicle brake energy recovery control method, vehicle and storage medium

Abstract

The application discloses a kind of vehicle braking energy recovery control methods, this method is applied to the vehicle equipped with electronic hydraulic brake system, vehicle controller and drive motor, by obtaining brake pedal signal identification driver intent and calculating target total braking torque.First, the system is based on vehicle parameter calculation current safety regenerative braking torque threshold, and preferentially request drive motor output electric brake torque.Then, by comparing target total braking torque with actual regenerative torque, real-time calculation required hydraulic compensation torque is accurately output by electronic hydraulic brake system, so as to form the closed-loop control of total braking force.The method realizes the dynamic optimization distribution and cooperation of electro-hydraulic braking force, maximizes the energy recovery efficiency on the basis of ensuring braking safety and pedal sense, effectively prolongs the vehicle cruising range.The application also discloses a kind of vehicle and storage medium.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology. Specifically, this invention relates to a vehicle braking energy recovery control method, a vehicle, and a storage medium. Background Technology

[0002] Most existing pure electric vehicles use vacuum-assisted hydraulic braking systems, which are technically mature, but their braking energy recovery efficiency needs to be optimized. In this system, the total braking force of the vehicle is a simple superposition of the regenerative braking force of the motor and the hydraulic braking force. The two are usually in an open-loop control state, lacking coordination and active distribution.

[0003] Vehicle controllers often rely on fixed vehicle speed and throttle opening to map torque, making it impossible to dynamically adjust and optimize electro- and hydraulic braking forces based on real-time operating conditions. This results in the system being unable to prioritize efficient electric braking to maximize energy recovery, while also tending towards conservatism due to concerns about excessive recovery causing vehicle instability. Ultimately, this restricts the simultaneous improvement of vehicle braking performance and driving range.

[0004] This invention provides a method for controlling vehicle braking energy recovery, particularly concerning how to achieve reasonable braking force distribution to improve the overall vehicle braking performance and energy recovery efficiency. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a vehicle braking energy recovery control method, the purpose of which is to achieve reasonable braking force distribution and improve the overall vehicle braking performance and energy recovery efficiency.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a vehicle braking energy recovery control method, applied to a pure electric vehicle equipped with an electro-hydraulic braking system, a vehicle controller, and a drive motor, comprising: Acquire the travel signal and pedal force signal of the brake pedal, identify the driver's braking intention based on the signals, and calculate the total target braking torque of the vehicle. Based on the inherent parameters of the vehicle and the real-time status parameters of the vehicle, calculate the permissible regenerative braking torque threshold under the current working conditions; The target regenerative braking torque is determined with the permitted regenerative braking torque threshold as the upper limit. The target regenerative braking torque request command is sent to the vehicle controller first, and the drive motor is controlled to output electric braking torque to meet the braking requirements. The system acquires the actual regenerative torque value of the drive motor in real time, calculates the torque difference between the target total braking torque and the actual regenerative torque value, determines the target hydraulic compensation braking torque based on the torque difference, and controls the electronic hydraulic braking system to output the corresponding hydraulic braking torque, so that the actual total braking torque of the vehicle matches the target total braking torque, forming a closed-loop control of the total braking force.

[0007] The inherent parameters of the vehicle include the vehicle's center of gravity position, vehicle curb weight, full load weight, wheel braking radius, and drive shaft configuration. The handling and stability limitation model is preset with a first permissible regenerative torque threshold curve corresponding to the no-load condition and a second permissible regenerative torque threshold curve corresponding to the full load condition. Both the first and second permissible regenerative torque threshold curves are characteristic curves in which the permissible regenerative torque decreases linearly with the increase of the master cylinder pressure.

[0008] When determining the target regenerative braking torque, the method also includes acquiring the current coasting regenerative torque value of the vehicle in real time and calculating the target regenerative braking torque based on a preset energy recovery control mode; the energy recovery control mode includes a coordinated energy recovery mode and a superimposed energy recovery mode.

[0009] When the energy recovery control mode is the coordinated energy recovery mode, the maximum value between the basic regenerative torque value corresponding to the braking demand and the current coasting regenerative torque value is taken as the target regenerative braking torque, and the basic regenerative torque value and the current coasting regenerative torque value are not superimposed.

[0010] When the energy recovery control mode is the superimposed energy recovery mode, the sum of the basic regenerative torque value corresponding to the braking demand and the current coasting regenerative torque value is used as the target regenerative braking torque.

[0011] When determining the target regenerative braking torque, the initial target regenerative braking torque is first calculated based on the road surface condition with a high coefficient of adhesion; the wheel slip ratio signal output by the electronic brake force distribution system (EBD) of the anti-lock braking system (ABS) is acquired in real time; when the wheel slip ratio exceeds the preset slip ratio threshold, the target regenerative braking torque is dynamically reduced based on the wheel slip ratio signal.

[0012] When the target regenerative braking torque can completely cover the target total braking torque, the electro-hydraulic braking system is controlled not to output hydraulic braking torque, and the vehicle enters the pure electric braking stage; when the target regenerative braking torque cannot completely cover the target total braking torque, the vehicle enters the hybrid braking stage, and the torque difference is supplemented by hydraulic braking torque; when the regenerative braking force is completely withdrawn, the vehicle enters the pure hydraulic braking stage, and the electro-hydraulic braking system outputs the full target total braking torque.

[0013] When the energy recovery operation meets the preset exit conditions, the regenerative braking torque output by the control drive motor gradually decreases, while the hydraulic braking torque output by the electronic hydraulic braking system increases accordingly, thus achieving a smooth transition from regenerative braking force to hydraulic braking force.

[0014] The present invention also provides a vehicle, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the vehicle braking energy recovery control method.

[0015] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the vehicle braking energy recovery control method described above.

[0016] The vehicle braking energy recovery control method of this invention constructs a closed-loop control system for the total braking force of the vehicle, solving the core defects of the open-loop distribution and inability to dynamically coordinate electro-hydraulic braking force in existing technologies, thus improving braking control accuracy and pedal feel consistency. It establishes a regenerative braking force handling and stability limitation model and adopts an electric braking priority distribution strategy to achieve reasonable braking force distribution, maximizing the conversion of braking kinetic energy into electrical energy for recharge, significantly improving energy recovery efficiency and effectively extending the driving range of pure electric vehicles. Based on the dual signals of pedal travel and pedal force to identify braking intent, it ensures a high degree of matching between braking force output and driver needs, further improving the accuracy of braking control. Attached Figure Description

[0017] Figure 1 This is a flowchart of the vehicle braking energy recovery control method of the present invention; Figure 2 This is a logic diagram of the braking system torque distribution enhancement energy recovery device of the present invention; Figure 3 This is a schematic diagram of the signal interaction of the braking system torque distribution enhancement energy recovery device of the present invention; Figure 4 This is a schematic diagram illustrating the model of the present invention; Figure 5 This is a flowchart illustrating the working state of the energy recovery (CRBS) system of this invention. Figure 6 The permissible regenerative torque corresponding to the target pressure under no-load conditions; Figure 7 The permissible regenerative torque corresponding to the target pressure under full load conditions; Figure 8 This is a flowchart of the braking energy recovery control strategy for a vacuum-assisted hydraulic braking system in the prior art. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0019] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," and similar expressions used in this document are for illustrative purposes only.

[0020] It should be noted that in the following embodiments, the terms "first," "second," and "third" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution; they are merely for the convenience of description.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] The technical concept of this invention includes: In the overall energy-saving technology system of pure electric vehicles, regenerative braking technology is one of the energy-saving means. This technology converts the kinetic energy of the vehicle during braking into electrical energy and stores it in the power battery through the regenerative braking condition of the motor, which can effectively reduce the energy consumption of the vehicle and increase the driving range. Currently, most pure electric vehicles still use traditional vacuum-assisted hydraulic braking systems. This system mainly provides the vacuum source required for braking assistance through a vacuum booster and a matching electric vacuum pump, and finally applies braking force to the wheels through a hydraulic braking circuit to achieve the vehicle's braking function. The above technical solution has the advantages of high technical maturity, a complete industrial supporting system, and controllable mass production costs, and therefore has been widely used in existing pure electric vehicle models. However, the inventors of this application have discovered through long-term research that the above-mentioned vacuum-assisted hydraulic braking system has many insurmountable technical defects when applied to pure electric vehicles, specifically as follows: First, under the architecture of this traditional braking system, the energy recovery torque output of the regenerative braking system is entirely limited by the constraints of the vehicle's handling stability. There is no unified closed-loop coordination and distribution mechanism between the hydraulic braking force and the regenerative braking force of the motor to meet the driver's braking needs. Their distribution is in an open-loop control state, unable to dynamically adjust the distribution ratio according to real-time braking conditions. This deficiency, on the one hand, prevents the braking system from fully utilizing its braking efficiency, limiting further improvements in vehicle braking performance; on the other hand, it fails to maximize the utilization of the motor's regenerative braking capability, resulting in insufficient recovery of recyclable energy during braking, leading to low energy recovery efficiency and hindering the improvement of the vehicle's driving range.

[0023] Secondly, in existing models equipped with vacuum-assisted hydraulic braking systems, the vehicle controller's braking energy recovery control strategy can only output a fixed motor recovery torque value based on different vehicle speeds and accelerator pedal openings. The total braking force of the vehicle is still in an open-loop control state. The vehicle controller cannot dynamically allocate and replace hydraulic braking force and motor regenerative braking force, and cannot objectively and accurately define and adjust the energy recovery intensity according to real-time braking conditions.

[0024] Third, for rear-wheel-drive pure electric vehicles, when the vehicle is within a preset speed range and the driver releases the accelerator pedal while simultaneously operating the brake pedal to regenerate braking energy, excessive braking energy recovery can lead to an excessively high proportion of rear axle braking force from the rear drive motor. This can easily cause vehicle skidding and other instability risks. Existing open-loop control solutions cannot maximize braking energy recovery capabilities and braking system efficiency while ensuring overall vehicle braking safety and handling stability; they cannot simultaneously balance braking safety, handling stability, and energy recovery efficiency.

[0025] Figure 8 The flowchart of the existing braking energy recovery control strategy is shown. This control process takes the vehicle being in motion as the sole prerequisite for entering the energy recovery mode. It divides the energy recovery mode into two mutually exclusive branches, coasting energy recovery and braking energy recovery, based solely on whether the brake pedal is depressed. It only sets a single exit condition to trigger the mode exit, lacking electro-hydraulic braking force coordination distribution, handling stability boundary verification, and smooth transition control logic. This clearly demonstrates the inherent defects of open-loop control in existing technologies. The technical solution of this invention is as follows: Firstly, such as Figures 1 to 7 As shown, this embodiment of the invention provides a vehicle braking energy recovery control method, applied to a pure electric vehicle equipped with an electro-hydraulic braking system, a vehicle controller, and a drive motor, comprising the following steps: S1. Acquire the travel signal and pedal force signal of the brake pedal, identify the driver's braking intention based on the signals, and calculate the total target braking torque of the vehicle. S2. Based on the inherent parameters of the vehicle and the real-time state parameters of the vehicle, establish a handling and stability limitation model for the regenerative braking force of the drive wheels, and calculate the permissible regenerative braking torque threshold under the current working conditions. S3. Determine the target regenerative braking torque with the permissible regenerative braking torque threshold as the upper limit, and send the target regenerative braking torque request command to the vehicle controller first, and control the drive motor to output electric braking torque to meet the braking requirements. S4. Real-time acquisition of the actual output regenerative torque value of the drive motor, calculation of the torque difference between the target total braking torque and the actual regenerative torque value, determination of the target hydraulic compensation braking torque based on the torque difference, control of the electronic hydraulic braking system to output the corresponding hydraulic braking torque, so that the actual total braking torque of the vehicle matches the target total braking torque, forming a closed-loop control of the total braking force.

[0026] In this embodiment of the invention, the vehicle is equipped with an electro-hydraulic braking system (EHB). The EHB system can identify the driver's braking intention based on the brake pedal input signal, calculate and control the output torque of the booster motor to achieve brake pedal assist. Simultaneously, by adjusting the booster motor's assist level, the assist characteristics of the EHB system can be altered to adapt to different driving styles such as standard, comfort, and sport. Furthermore, based on the energy recovery triggering conditions, during the braking process when the driver depresses the brake pedal, the EHB system's controller autonomously coordinates and distributes the ratio of regenerative braking force from the motor to hydraulic braking force, prioritizing regenerative braking force to meet braking needs. During the energy recovery exit phase, a smooth transition from regenerative braking force to hydraulic braking force is achieved. This significantly improves braking energy utilization and vehicle range while maintaining consistent brake pedal feel, overcoming some of the shortcomings of traditional vacuum-assisted braking systems and providing greater freedom in braking system control.

[0027] In this embodiment of the invention, the problem of the total braking force of the vehicle being in an open loop is solved. The vehicle controller cannot switch the hydraulic braking to electric braking, that is, the total braking force cannot be distributed. Excessive braking energy recovery intensity leads to vehicle instability and fishtailing, while insufficient intensity does not contribute much to the range.

[0028] In this embodiment of the invention, an electro-hydraulic control system can determine the driver's braking intention based on the brake pedal input and calculate the output torque of the motor to provide assistance to the brake pedal. By changing the amount of motor assistance, the assistance characteristics of the electro-hydraulic control system can be altered, thereby achieving different driving styles such as standard, comfort, and sport. Furthermore, while meeting the conditions for energy recovery, during the braking process when the driver depresses the pedal, the controller of the electro-hydraulic control system autonomously allocates the electro-hydraulic braking torque ratio, prioritizing the use of electric braking torque to complete braking. During the energy recovery exit phase, the electric braking torque smoothly transitions to hydraulic braking, ensuring a comfortable braking experience while maximizing energy efficiency and improving key parameters such as driving range.

[0029] The vehicle braking energy recovery control method provided in this embodiment of the invention mainly includes: Braking is applied based on pedal force and travel displacement; Real-time monitoring of the actual regenerative torque of the motor: This enables closed-loop regulation of the total braking torque, ensuring good response and smoothness; Establish a driver braking intention model: based on driver intention recognition and energy recovery intervention / exit permission conditions, ensure smooth energy recovery; In vehicle control, the control of energy recovery combined with coasting value is generally divided into two types: coordinated and superimposed. Coordinated energy recovery: The vehicle uses the larger of the braking energy recovery torque and coasting energy recovery torque when handling braking energy recovery torque, without superimposing them. The TBS (electric brake assist system) does not monitor the current coasting torque value of the vehicle. The advantage of this approach is that the braking feel is better when the opening is large. After the braking torque exceeds a certain target, it is equivalent to abandoning the coasting energy recovery torque that worsens the braking feel (this torque is generally looked up in a table based on the vehicle speed, and the feel is not good). Superimposed energy recovery: The vehicle uses the summation principle when dealing with braking energy recovery torque and coasting energy recovery torque. TBS needs to monitor the current coasting torque value of the vehicle and then apply for braking recovery torque based on this. The characteristic of this processing is that it is more biased towards the single-pedal mode of electric vehicles. In addition to the braking force generated by the person pressing the pedal, there is a coasting braking force that is not related to the braking intention, resulting in a poor user experience. Based on the vehicle parameters, such as center of gravity position, vehicle mass, braking radius, etc., the braking force of the vehicle's drive wheels is applied to limit handling stability. During energy recovery, the required braking force of the entire vehicle is calculated based on the pedal depth and then converted into the rear wheel braking torque. After consulting with the current recoverable torque limit and handling stability limit provided by the vehicle controller, the current target electric braking recovery torque is requested from the vehicle controller via the bus. The controller receives the torque value of the main drive motor and the coasting braking torque value from the vehicle controller, and calculates the current electric braking torque according to the vehicle energy recovery scheme (coordination, superposition). Based on the vehicle braking torque calculated according to the pedal depth, the electric braking torque generated by the motor reverse drag is subtracted, and hydraulic compensation is performed to meet the braking requirements. (At the same time, if the controller is a front and rear disc type, this section will additionally compensate for hydraulic braking to increase the decoupling stroke in order to meet the decoupling pedal feel.)

[0030] Figure 1 This diagram illustrates the hierarchical control architecture of the braking energy recovery control method of the present invention, which consists of three levels: upper, middle, and lower. The upper level is the braking intent recognition and demand analysis layer. Using brake pedal displacement and vehicle status as inputs, it identifies the driver's braking intent and analyzes the braking intensity and braking force requirements, establishing a driver braking intent model. The middle level is the braking force distribution and coordination control layer. Based on the braking force requirements output from the upper level, it coordinates the distribution of hydraulic and electric braking forces, dividing it into three control modes: pure electric braking, hybrid braking, and pure hydraulic braking, and outputs corresponding pressure and torque control commands. The lower level is the actuator and vehicle feedback layer, including the drive motor, anti-lock braking system, and hydraulic braking system. It receives control commands from the middle level, executes braking actions, and feeds back the execution status and vehicle motion status to the upper and middle levels, forming a closed-loop control.

[0031] Specifically, in this embodiment of the invention, the electro-hydraulic braking system communicates bidirectionally with the vehicle controller, drive motor controller, and anti-lock braking system via the vehicle CAN bus. Step S1 is the requirement analysis stage for braking control, as detailed in the appendix to the specification. Figure 1 The upper-level control logic of the hierarchical control architecture shown is used to identify and output the driver's braking needs. In step S1 above, the brake pedal travel signal and pedal force signal are collected in real time through the vehicle's pedal displacement sensor and pedal force sensor. Based on the preprocessed pedal travel signal and pedal force signal, feature parameters such as pedal travel percentage, pedal travel change rate, pedal force, and pedal force change rate are extracted to identify the driver's braking intention and calculate the total target braking torque of the vehicle. In this embodiment of the invention, three typical braking intentions are predefined: light braking, normal braking, and emergency braking.

[0032] Figure 2This diagram illustrates the braking force distribution logic of the present invention, with the horizontal axis representing braking intensity and the vertical axis representing braking force output value. The diagram clearly shows that the total braking force of the vehicle is composed of the superposition of hydraulic and electric braking forces, and clearly presents the core distribution logic of prioritizing electric braking in this invention: within the entire range of increasing braking intensity, electric braking force is prioritized to meet braking requirements. When the electric braking force reaches its permissible upper limit, hydraulic braking force is used to supplement the remaining braking force gap, thereby maximizing the proportion of electric braking and improving braking energy recovery efficiency.

[0033] In this embodiment of the invention, the real-time load quality signal of the vehicle sent by the vehicle controller is obtained in real time through the vehicle CAN bus, and the permissible regenerative torque threshold under the current operating condition is dynamically updated based on the matching of the corresponding permissible regenerative torque threshold curve according to the real-time load quality signal of the vehicle.

[0034] In this embodiment of the invention, the real-time vehicle status parameters include drive motor speed, current actual motor torque, maximum allowable motor recovery torque of the vehicle controller, current gear, vehicle Ready status, ABS handling and stability association activation flag, vehicle speed, four-wheel wheel speed, and ABS fault information.

[0035] In this embodiment of the invention, the inherent parameters of the vehicle include the vehicle's center of gravity position, vehicle's curb weight, full load weight, wheel braking radius, and drive shaft configuration. Based on parameters such as the vehicle's center of gravity position, vehicle weight, and braking radius, the vehicle's drive wheels are subjected to handling and stability restrictions to calculate and limit the electric braking value. Energy recovery is generally calculated based on no-load conditions to cover all vehicle weight ranges.

[0036] Step S2 in this embodiment of the invention is a safety boundary limiting step for braking control, corresponding to Figure 4 The control model shown establishes logic, Figure 6 and Figure 7 The empty and fully loaded permissible regenerative torque characteristic curves shown are used to maximize the release of the regenerative braking capability of the drive motor while ensuring the vehicle's handling stability.

[0037] In step S2 of this embodiment, the input parameters of the handling and stability limiting model are divided into two categories: inherent vehicle parameters and real-time vehicle state parameters. The inherent vehicle parameters are fixed parameters calibrated during the vehicle design phase and pre-stored in the controller's storage unit. These include the vehicle's curb weight, full load weight, vehicle center of gravity height, horizontal distance from the center of gravity to the front axle, horizontal distance from the center of gravity to the rear axle, wheel rolling radius, drive shaft configuration, and tire reference adhesion coefficient. The real-time vehicle state parameters are acquired in real-time via the CAN bus. Figure 3 The CAN signal interaction link shown includes real-time vehicle speed, four-wheel speed, real-time vehicle load mass, brake master cylinder pressure, ABS system activation flag, wheel slip ratio signal, ABS fault information, and the maximum allowable regenerative torque of the motor issued by the vehicle controller.

[0038] Furthermore, in embodiments of the present invention, such as Figure 6 and Figure 7 As shown, the handling and stability limiting model pre-sets a first permissible regenerative torque threshold curve for no-load conditions and a second permissible regenerative torque threshold curve for full-load conditions. Both the first and second permissible regenerative torque threshold curves exhibit a linear decrease in permissible regenerative torque as the master cylinder pressure increases. The goodness of fit R between the first and second permissible regenerative torque threshold curves is... 2 =1, all exhibiting the characteristic of linearly decreasing permissible regenerative torque as the master cylinder pressure increases.

[0039] The first permissible regenerative torque threshold curve defines the upper limit of the maximum permissible regenerative braking torque under unloaded vehicle conditions to ensure driving stability under various possible road adhesion conditions. For example... Figure 6 As shown, the fitting formula for the first permissible regenerative torque threshold curve under no-load conditions is y1 = -22.013x + 1612.4, where y1 is the permissible regenerative torque threshold under no-load conditions, x is the current brake master cylinder pressure, the horizontal axis is the master cylinder pressure (unit: bar), and the vertical axis is the rear axle regenerative torque (unit: N•m). The maximum permissible regenerative torque is 1612.4 N•m when the master cylinder pressure is 0. This threshold curve indicates that as the driver's braking demand increases, the intensity of energy recovery (i.e., regenerative torque) allowed by the system through the motor needs to be reduced accordingly to prevent drive wheel lock-up or instability. In the control strategy, when the actual vehicle mass cannot be accurately known, this curve will be used by default to limit the load to ensure the most basic safety margin.

[0040] The second permissible regeneration torque threshold curve corresponds to the ideal recycling condition where the vehicle is fully loaded and the system determines the road surface to be of high adhesion. For example... Figure 7 As shown, the fitting formula for the second permissible regenerative torque threshold curve under full load conditions is y2 = -22.013x + 3224.9, where y2 is the permissible regenerative torque threshold under full load conditions, x is the current brake master cylinder pressure, the horizontal axis is the master cylinder pressure (unit: bar), and the vertical axis is the rear axle regenerative torque (unit: N•m). The maximum permissible regenerative torque is 3224.9 N•m when the master cylinder pressure is 0. The upper limit of the regenerative torque allowed by this threshold curve is significantly higher than that of the second permissible regenerative torque threshold curve. When it is confirmed that the vehicle is under full load, the control system can safely switch to this threshold curve. This can significantly broaden the application range of electric braking force while ensuring handling stability and safety, thereby greatly improving the depth and total amount of energy recovery in most braking scenarios for the driver, directly contributing to the improvement of driving range.

[0041] The two sets of curves mentioned above serve as the quantitative basis for the handling stability limitation model in this embodiment of the invention, and are used to dynamically match the safe upper limit of regenerative torque under different load conditions. Based on the acquired real-time load mass signal of the vehicle, the corresponding characteristic curve is matched, and the permissible regenerative torque threshold under the current condition is dynamically updated, thereby achieving dynamic adaptation that prioritizes handling stability safety under no-load conditions and maximizes energy recovery efficiency under full-load conditions.

[0042] Step S2 ultimately outputs the permissible regenerative braking torque threshold of the drive wheels under the current operating conditions. This threshold is the upper limit of the subsequent target regenerative braking torque, ensuring that the regenerative braking control is always within the safe handling boundary.

[0043] The aforementioned preset curve limitation will be combined with the real-time wheel slip ratio feedback provided by the electronic brake force distribution (EBD) function of the anti-lock braking system (ABS) to form a dual guarantee of feedforward preset and feedback correction, further optimizing control accuracy and safety.

[0044] In this embodiment of the invention, step S3 uses the permissible regenerative torque threshold calculated in step S2 as the upper limit to determine the target regenerative braking torque. The initial value of the target regenerative braking torque is calibrated and calculated based on the permissible regenerative torque threshold under high adhesion coefficient road conditions to maximize the braking energy recovery depth under normal paved road conditions. In this step, when determining the target regenerative braking torque, the initial target regenerative braking torque is first calculated based on the high adhesion coefficient road conditions; the wheel slip ratio signal output by the electronic brake force distribution function of the anti-lock braking system is acquired in real time through the vehicle CAN bus; when the wheel slip ratio exceeds the preset slip ratio threshold, the target regenerative braking torque is dynamically reduced based on the wheel slip ratio signal.

[0045] If the preset slip ratio threshold is 20%, when the wheel slip ratio is detected to exceed the preset slip ratio threshold, it is determined that the vehicle is in a low-adhesion coefficient road surface condition. Based on the extent to which the wheel slip ratio exceeds the threshold, the target regenerative braking torque is linearly reduced until the wheel slip ratio falls back to the preset threshold range. This achieves adaptive control that maximizes energy recovery on high-adhesion coefficient roads and prioritizes handling stability on low-adhesion coefficient roads.

[0046] In this embodiment of the invention, determining the target regenerative braking torque further includes real-time acquisition of the vehicle's current coasting regenerative torque value. In step S3, when determining the target regenerative braking torque, the vehicle's current coasting regenerative torque value issued by the vehicle controller is acquired in real-time via the vehicle's CAN bus, and the target regenerative braking torque is calculated based on a preset energy recovery control mode; the energy recovery control mode includes a coordinated energy recovery mode and a superimposed energy recovery mode.

[0047] Furthermore, when the energy recovery control mode is the coordinated energy recovery mode, the maximum value between the basic regenerative torque value corresponding to the braking demand and the current coasting regenerative torque value is taken as the final target regenerative braking torque, without superimposing the basic regenerative torque value and the current coasting regenerative torque value. In this mode, when the basic regenerative torque value corresponding to the braking demand is greater than the coasting regenerative torque value, the coasting regenerative torque is discarded to avoid the deterioration of braking feel caused by the superposition of coasting torque and braking recovery torque, and to ensure the smoothness of brake pedal operation.

[0048] Furthermore, when the energy recovery control mode is the superimposed energy recovery mode, the sum of the basic regenerative torque value corresponding to the braking demand and the current coasting regenerative torque value is used as the final target regenerative braking torque. In this mode, the total amount of energy recovered during braking can be maximized, adapting to the usage requirements of one-pedal driving mode.

[0049] The aforementioned basic regenerative torque value corresponding to the braking demand refers to the regenerative torque benchmark value calculated solely based on the braking demand generated by the driver pressing the brake pedal, which is conventionally referred to in the art as the braking energy recovery torque, i.e., the electric braking torque. This value is independent of the coasting regenerative torque value under the vehicle coasting energy recovery condition and does not include the coasting regenerative torque component.

[0050] The aforementioned coasting regenerative torque value refers to the regenerative torque value calculated and controlled by the vehicle controller based on the vehicle's operating state when the vehicle is in motion and the brake pedal is not depressed, which is conventionally referred to in the art as coasting energy recovery torque.

[0051] In this embodiment of the invention, in step S4 above, when the target regenerative braking torque can completely cover the target total braking torque, the electronic hydraulic braking system is controlled not to output hydraulic braking torque, and the vehicle enters the pure electric braking stage; when the target regenerative braking torque cannot completely cover the target total braking torque, the vehicle enters the hybrid braking stage, and the torque difference is supplemented by hydraulic braking torque; when the regenerative braking force is completely withdrawn, the vehicle enters the pure hydraulic braking stage, and the electronic hydraulic braking system outputs the full target total braking torque.

[0052] Specifically, step S4, based on the target total braking torque of the vehicle obtained in step S1 and the target regenerative braking torque determined in step S3, executes a braking force coordination and distribution strategy that prioritizes electric braking, which is divided into three consecutive control stages: 1. Pure electric braking phase: When the target regenerative braking torque can completely cover the total target braking torque of the vehicle, that is, when the value of the target regenerative braking torque is greater than or equal to the total target braking torque of the vehicle corresponding to the driver's braking demand, a regenerative braking request command matching the total target braking torque of the vehicle is sent to the vehicle controller, controlling the drive motor to output the corresponding electric braking torque; at the same time, the electro-hydraulic braking system is controlled not to output hydraulic braking torque, and the vehicle enters the pure electric braking phase, maximizing the kinetic energy recovery efficiency during the braking process.

[0053] 2. Hybrid Braking Phase: When the target regenerative braking torque cannot fully cover the total target braking torque of the vehicle, a regenerative braking request command is sent to the vehicle controller with the target regenerative braking torque as the upper limit, controlling the drive motor to output the corresponding electric braking torque; at the same time, the torque difference between the total target braking torque of the vehicle and the actual regenerative torque value output by the drive motor is calculated, and the target hydraulic compensation braking torque is determined based on the torque difference, controlling the electro-hydraulic braking system to output the corresponding hydraulic braking torque, and the vehicle enters the hybrid braking phase, which fully matches the driver's braking needs while ensuring braking energy recovery efficiency.

[0054] 3. Pure hydraulic braking stage: When the regenerative braking force meets the preset exit conditions and completely exits, the regenerative braking request command sent to the vehicle controller is stopped, and the electronic hydraulic braking system is controlled to output all hydraulic braking torque that matches the total target braking torque of the vehicle. The vehicle enters the pure hydraulic braking stage to ensure the safety and reliability of the braking function under extreme conditions.

[0055] like Figure 4 As shown, during the entire braking control process, the relative displacement signal of the brake input push rod is acquired in real time through the displacement sensor built into the electro-hydraulic braking system. Based on the relative displacement signal, the decoupling gap of the braking system is determined. When the decoupling gap is lower than the preset design threshold, the brake master cylinder of the electro-hydraulic braking system is controlled to start working and output hydraulic braking torque, thereby ensuring the linear correspondence between the brake pedal stroke and the braking force output and ensuring the stability of the brake pedal feel.

[0056] When a vehicle is equipped with a front and rear disc brake system, while outputting a hydraulic braking torque corresponding to the target hydraulic compensation braking torque, the electronic hydraulic braking system is controlled to output additional compensation hydraulic braking force to increase the decoupling stroke of the brake pedal, further optimize the operation feedback of the brake pedal, and improve the consistency of pedal feel under different braking conditions.

[0057] In this embodiment of the invention, when the energy recovery condition meets the preset exit conditions, the regenerative braking torque output by the control drive motor gradually decreases, and the hydraulic braking torque output by the electronic hydraulic braking system increases accordingly, so as to achieve a smooth transition from regenerative braking force to hydraulic braking force.

[0058] like Figure 5 As shown, the preset CRBS coordinated regenerative braking system has a working state machine, which includes CRBS inactive state, CRBS active state, CRBS working state, and CRBS deactivated state. It detects fault signals and ABS deactivated signals in real time. When a preset fault signal or ABS deactivated signal is detected, it controls the CRBS to switch from the working state to the deactivated state and terminates the regenerative braking control.

[0059] Specifically, when the energy recovery condition meets the preset exit conditions, the regenerative braking smooth exit control is executed. The regenerative braking torque output by the drive motor is controlled to gradually decrease according to the preset slope, and the hydraulic braking torque output by the electro-hydraulic braking system is simultaneously controlled to increase according to the corresponding slope. This ensures that the total braking torque of the vehicle is always consistent with the target total braking torque required by the driver, achieving a smooth transition from regenerative braking force to hydraulic braking force without impact. This avoids braking jerking during the regenerative braking exit process and ensures the consistency of the brake pedal feel.

[0060] When the vehicle is in the Ready state, the vehicle's motion status and brake pedal status signals are monitored in real time, and the identification and switching control of energy recovery conditions are executed: When the vehicle speed is detected to be greater than the preset minimum energy recovery speed threshold, the vehicle is in motion, and the brake pedal is not depressed, the vehicle is controlled to enter the coasting energy recovery mode. The vehicle controller controls the drive motor to output the corresponding coasting regeneration torque to realize the recovery of kinetic energy during the vehicle's coasting process. When the vehicle is detected to be in motion and the brake pedal is depressed and the pedal travel exceeds the preset brake free travel threshold, the vehicle is controlled to enter the brake energy recovery mode and the aforementioned electro-hydraulic brake force coordination distribution and brake energy recovery control are executed. When the energy recovery condition meets the preset exit conditions, the vehicle is controlled to exit the energy recovery condition. The preset exit conditions include any one or more combinations of the following: the vehicle speed is lower than the preset minimum energy recovery speed threshold, the anti-lock braking system (ABS) is activated, the braking system malfunctions, and the driver releases the brake pedal to any point within the free travel range.

[0061] In this embodiment of the invention, the vehicle has three preset driving modes: comfort mode, standard mode, and sport mode. Different driving modes correspond to different assist characteristic curves of the electro-hydraulic braking system. The currently selected driving mode is obtained in real time, and the corresponding assist characteristic curve is matched. The braking assist is adjusted by adjusting the output torque of the assist motor of the electro-hydraulic braking system.

[0062] Throughout the braking control process, the vehicle CAN bus receives the signal of the currently selected driving mode from the vehicle controller or body domain controller in real time, and matches it with the assist characteristic curve corresponding to the driving mode. Based on the matched assist characteristic curve and the real-time collected brake pedal force signal, the output torque of the assist motor of the electro-hydraulic braking system is adjusted to achieve dynamic adjustment of the braking assist magnitude, thereby adapting to the driving style needs of different drivers.

[0063] The vehicle braking energy recovery control method of the present invention has the following technical effects and advantages: 1. During energy recovery control, the vehicle's drive wheels are subjected to handling and stability restrictions based on vehicle parameters, road surface parameters, center of gravity position, vehicle mass, braking radius, and other parameters, thereby limiting the electric braking value.

[0064] 2. The sub-hydraulic braking system itself cannot obtain the overall vehicle mass status. Therefore, in order to consider handling stability, energy recovery is generally calculated based on no-load conditions to cover all vehicle weight ranges. The sub-hydraulic braking system can obtain the mass / weight signal sent by the vehicle controller from the CAN bus to switch the braking curve in real time, which greatly improves the energy recovery depth under full load while ensuring no-load handling stability.

[0065] Fully loaded high-adhesion braking can maximize the depth of energy recovery, increase the proportion of electric braking at the same opening degree, and broaden the opening degree that can be used for electric braking. The actual energy recovery value is limited by the assist curve and the permissible regenerative torque, and is calibrated according to the actual vehicle.

[0066] 3. This method first analyzes the driver's braking demand based on the brake pedal status and obtains the required braking torque. Then, it calculates the maximum braking power of the motor based on the battery and motor status. On this basis, it positively distributes the braking torque between the motor system and the hydraulic system. By adjusting the braking torque generated by the motor system, the braking force output by the hydraulic system is compensated, ensuring that the final braking torque acting on the vehicle is consistent with the driver's demand, thus solving the problems of underutilization of braking intensity and insufficient energy recovery.

[0067] Secondly, embodiments of the present invention also provide a vehicle, which is a pure electric vehicle, comprising: a memory, a communication interface, a processor, and a computer program stored in the memory and executable on the processor. The processor, the communication interface, and the memory communicate with each other via a communication bus. When the processor executes the program, it implements the vehicle braking energy recovery control method provided in the above embodiments.

[0068] The aforementioned communication bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc.

[0069] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0070] The processor can be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0071] Thirdly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the vehicle braking energy recovery control method provided in the above embodiments.

[0072] According to embodiments of the present invention, the computer-readable storage medium may be a non-volatile computer-readable storage medium, such as including, but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the present invention, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0073] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A vehicle braking energy recovery control method, including: Acquire the travel signal and pedal force signal of the brake pedal, identify the driver's braking intention, and calculate the total target braking torque of the vehicle; Based on the inherent parameters of the vehicle and the real-time status parameters of the vehicle, calculate the permissible regenerative braking torque threshold under the current working conditions; The target regenerative braking torque is determined with the permitted regenerative braking torque threshold as the upper limit. The target regenerative braking torque request command is sent to the vehicle controller first, and the drive motor is controlled to output electric braking torque to meet the braking requirements. The system acquires the actual regenerative torque value of the drive motor in real time, calculates the torque difference between the target total braking torque and the actual regenerative torque value, determines the target hydraulic compensation braking torque based on the torque difference, and controls the electronic hydraulic braking system to output the corresponding hydraulic braking torque, so that the actual total braking torque of the vehicle matches the target total braking torque, forming a closed-loop control of the total braking force.

2. The vehicle braking energy recovery control method according to claim 1, characterized in that, The inherent parameters of the vehicle include the vehicle's center of gravity position, vehicle curb weight, full load weight, wheel braking radius, and drive shaft configuration. The handling and stability limitation model is preset with a first permissible regenerative torque threshold curve corresponding to the no-load condition and a second permissible regenerative torque threshold curve corresponding to the full load condition. Both the first and second permissible regenerative torque threshold curves are characteristic curves in which the permissible regenerative torque decreases linearly with the increase of the master cylinder pressure.

3. The vehicle braking energy recovery control method according to claim 1, characterized in that, When determining the target regenerative braking torque, the method also includes acquiring the current coasting regenerative torque value of the vehicle in real time and calculating the target regenerative braking torque based on a preset energy recovery control mode; the energy recovery control mode includes a coordinated energy recovery mode and a superimposed energy recovery mode.

4. The vehicle braking energy recovery control method according to claim 3, characterized in that, When the energy recovery control mode is the coordinated energy recovery mode, the maximum value between the basic regenerative torque value corresponding to the braking demand and the current coasting regenerative torque value is taken as the target regenerative braking torque, and the basic regenerative torque value and the current coasting regenerative torque value are not superimposed.

5. The vehicle braking energy recovery control method according to claim 3, characterized in that, When the energy recovery control mode is the superimposed energy recovery mode, the sum of the basic regenerative torque value corresponding to the braking demand and the current coasting regenerative torque value is used as the target regenerative braking torque.

6. The vehicle braking energy recovery control method according to claim 1, characterized in that, When determining the target regenerative braking torque, the initial target regenerative braking torque is first calculated based on the road surface condition with a high coefficient of adhesion; the wheel slip ratio signal output by the electronic brake force distribution function of the anti-lock braking system is acquired in real time; when the wheel slip ratio exceeds the preset slip ratio threshold, the target regenerative braking torque is dynamically reduced based on the wheel slip ratio signal.

7. The vehicle braking energy recovery control method according to claim 1, characterized in that, When the target regenerative braking torque can completely cover the target total braking torque, the electro-hydraulic braking system is controlled not to output hydraulic braking torque, and the vehicle enters the pure electric braking stage; when the target regenerative braking torque cannot completely cover the target total braking torque, the vehicle enters the hybrid braking stage, and the torque difference is supplemented by hydraulic braking torque; when the regenerative braking force is completely withdrawn, the vehicle enters the pure hydraulic braking stage, and the electro-hydraulic braking system outputs the full target total braking torque.

8. The vehicle braking energy recovery control method according to claim 1, characterized in that, When the energy recovery operation meets the preset exit conditions, the regenerative braking torque output by the control drive motor gradually decreases, while the hydraulic braking torque output by the electronic hydraulic braking system increases accordingly, thus achieving a smooth transition from regenerative braking force to hydraulic braking force.

9. A vehicle, characterized in that, include: The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the vehicle braking energy recovery control method as described in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the vehicle braking energy recovery control method as described in any one of claims 1 to 8.

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