Regenerative braking optimization method and system based on energy recovery trend decline judgment

Abstract

This invention discloses a regenerative braking optimization method and system based on energy recovery trend decline judgment, comprising: acquiring vehicle driving process state information using an in-vehicle sensor system and a state estimator; an energy recovery trend decline judgment module establishing an energy recovery trend model based on the received data, determining the energy recovery trend decline state, and sending a signal to the control module; if the trend decline state is not entered, the vehicle continues the normal regenerative braking control process; if the vehicle enters the trend decline state, without changing the existing electric motor power, the front and rear axle braking force distribution coefficients are adjusted, taking into account the vehicle state and making full use of ground adhesion conditions, so as to ensure braking performance while meeting recovery efficiency; the execution module executes according to the instructions of the control module. This invention enables an effective dynamic adjustment mechanism to be entered when the braking energy recovery trend declines, ensuring the stability of energy recovery efficiency and braking performance.

Description

Technical Field

[0001] This invention relates to the field of automotive energy recovery technology, and in particular to a regenerative braking optimization method and system based on the judgment of energy recovery trend decline. Background Technology

[0002] With the widespread application of electric vehicles, regenerative braking technology has become a key element in improving energy efficiency. During deceleration or braking, the electric motor converts the vehicle's kinetic energy into electrical energy and recharges the battery, thereby extending the vehicle's driving range. However, traditional regenerative braking control strategies are often relatively simple, making it difficult to fully utilize the maximum efficiency of regenerative braking under complex driving conditions. Furthermore, when the braking energy recovery trend weakens, there is a lack of effective dynamic adjustment mechanisms, resulting in limited energy recovery efficiency and insufficient braking performance stability. In this situation, the braking force originally provided by the energy recovery system will weaken, leading to problems such as increased braking distance and accelerated wear of the braking system. In addition, the insufficient braking performance stability caused by the weakening of the braking energy recovery trend makes the feel of the brake pedal unpredictable. A normal braking system should provide a linear braking feel, meaning that there is a stable correspondence between the force applied by the driver to the brake pedal and the vehicle's deceleration. However, when the energy recovery system malfunctions, especially when there is a lack of adjustment mechanisms near its limits, the feel of the brake pedal may become very "soft" or "hard." For example, during braking, the driver may feel a sudden change in pedal force, which is due to a problem with the coordination between the energy recovery system and the mechanical braking system. This abnormal pedal feel can interfere with the driver's judgment of braking operations, leading to untimely or excessive braking.

[0003] The current shortcomings in vehicle regenerative braking system control methods include:

[0004] 1. Limited vehicle energy recovery efficiency and insufficient exploitation of recovery potential. Actual driving conditions are complex and varied. As vehicle speed decreases, the motor power also decreases. When the vehicle speed drops below the motor output below the battery charging power limit, mechanical braking must intervene, resulting in insufficient utilization of kinetic energy and a significant reduction in energy recovery efficiency. Furthermore, the lack of accurate vehicle braking mathematical models makes it difficult to precisely assess and predict the braking energy recovery potential under different operating conditions, hindering more refined energy recovery control and causing some energy recovery opportunities to be overlooked.

[0005] 2. Poor braking comfort. Regenerative braking capability varies with vehicle speed and battery status. If it is not well coordinated with basic braking, it can cause fluctuations in deceleration during braking, affecting the comfort of the driver and passengers.

[0006] 3. Complex Braking Force Distribution and Coordination Control. During braking, precise coordination of braking force distribution between mechanical braking and regenerative braking is required to achieve optimal energy recovery and braking effect. However, due to the complexity of the vehicle's braking system, involving multiple components and control links, achieving perfect coordination between the two is not easy, and braking force distribution strategies under different operating conditions still need further optimization. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the aforementioned problems, this invention provides a regenerative braking optimization method and system based on energy recovery trend decline judgment, which solves the problem of limited energy recovery efficiency, insufficient braking performance stability, and abnormal brake pedal feel caused by the lack of an effective dynamic adjustment mechanism when the braking energy recovery trend declines.

[0009] (II) Technical Solution

[0010] To address the aforementioned technical problems, this invention provides a regenerative braking optimization method based on energy recovery trend decline judgment, comprising:

[0011] S1. Obtain vehicle driving state information using in-vehicle sensor systems and state estimators, and transmit the state information to the energy recovery trend decline judgment module and control module. The state information includes motor speed n. r And vehicle acceleration a V ;

[0012] S2. The energy recovery trend decline judgment module establishes an energy recovery trend model based on the received data: calculating the regenerative braking power P at the current moment. r By analyzing consecutive N p Regenerative braking energy E within a time interval Δt r Perform curve fitting, calculate the slope k of the fitted energy recovery curve, set the trend decline threshold k0, if k≤k0, determine the energy recovery trend decline state, send a signal to the control module, and proceed to step S4; otherwise, proceed to step S3.

[0013] S3. The control module controls the vehicle to continue the normal regenerative braking control process and proceeds to step S5.

[0014] S4. When the vehicle enters a tendency to decelerate, the control module, without changing the existing electric motor's power, adjusts the front-to-rear axle braking force distribution coefficient, taking into account the vehicle's condition and fully utilizing ground adhesion conditions, to ensure braking performance while maintaining recovery efficiency. The constraints of the front-to-rear axle braking force distribution coefficient include:

[0015] ECE regulations:

[0016]

[0017] Constraints of the ideal braking force distribution curve:

[0018]

[0019] Constraints on the coefficient of adhesion of the road surface:

[0020]

[0021] Solve the braking performance optimization problem of an electric vehicle when its energy recovery is nearing a decline state, with the optimization objective being:

[0022]

[0023] Based on the calculated optimal braking force distribution coefficient, the rear axle braking force is calculated as follows:

[0024] F br =F reg +F hvd =(1-β)F Xb

[0025]

[0026] In the formula, β is the front axle braking force distribution coefficient, a and b are the horizontal distances from the front and rear axles to the center of gravity, respectively, L is the distance between the front and rear axles, and h is the horizontal distance between the front and rear axles. g Let z be the height from the ground to the center of mass, and z be the braking intensity, defined as the vehicle acceleration a. V The ratio of α to the gravitational acceleration g. m φ is a proportionality coefficient, representing a moderate amount of regenerative braking energy recovery while ensuring braking stability. f and φ r These are the coefficients of adhesion for the front and rear wheels, respectively, where μ is the road surface adhesion coefficient, and F is the coefficient of adhesion for the front and rear wheels. Xb For the total braking force, F br For rear axle braking force, F reg For regenerative braking force of the motor, F hvd For front axle hydraulic braking force, i g For the gear ratio of the transmission, i o The transmission ratio of the main reducer, η t Let r be the mechanical efficiency of the transmission system and the wheel radius.

[0027] S5. The execution module executes the instructions from the control module and continuously monitors the vehicle's status information.

[0028] Furthermore, in S2, the calculation of the regenerative braking power P at the current moment... rinclude:

[0029]

[0030] In the formula, η m T represents the power generation efficiency of the motor. m T is the regenerative braking torque of the motor. N P is the rated torque of the motor. n n is the power of the motor. r n is the actual speed of the motor. n This is the rated speed of the motor.

[0031] Furthermore, in S2, the regenerative braking energy E r for: The slope k is:

[0032] Furthermore, in S3, when the vehicle continues the normal regenerative braking control process, the vehicle braking force distribution coefficient is a fixed value set at the factory. The control module determines the appropriate ratio of regenerative braking to mechanical braking based on the current operating conditions and executes the braking operation through the execution module.

[0033] Furthermore, the status information also includes vehicle speed v and battery charge state of charge (SOC). When the battery charge state of charge exceeds a set threshold state of charge (SOC)... max When the vehicle speed v is below a set threshold v, regenerative braking will cease. min At that time, regenerative braking will not be performed.

[0034] Furthermore, the present invention also discloses an electric vehicle regenerative braking optimization system based on energy recovery trend decline judgment, and the electric vehicle regenerative braking optimization method based on energy recovery trend decline judgment includes: an in-vehicle sensor system, a state estimator, an energy recovery trend decline judgment module, a control module, and an execution module.

[0035] Furthermore, the present invention also discloses a non-transitory computer-readable storage medium storing computer instructions that cause the computer to perform the method described thereon.

[0036] (III) Beneficial Effects

[0037] The above-described technical solution of the present invention has the following advantages:

[0038] (1) This invention achieves refined monitoring and prediction of the trend of regenerative braking energy recovery by judging whether the energy recovery of electric vehicles has reached the trend of decline. When the trend of decline is determined, the front and rear axle braking force distribution coefficients of electric vehicles will be dynamically adjusted, thereby maximizing the recovery of energy while ensuring the stability of braking performance. The execution module strictly follows the instructions of the control module to precisely control the braking hydraulic system and the power generation state of the motor, ensuring that the vehicle decelerates smoothly and the energy recovery process proceeds smoothly. During the entire braking process, the modules work together to effectively overcome the problems of existing electric vehicle regenerative braking in terms of energy recovery efficiency, braking comfort, braking force distribution and control. Attached Figure Description

[0039] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0040] Figure 1 This is a flowchart of the regenerative braking optimization method based on energy recovery trend decline according to an embodiment of the present invention;

[0041] Figure 2 This is a reference structural diagram of a rear-wheel drive electric vehicle according to an embodiment of the present invention;

[0042] Figure 3 This is a diagram illustrating the vehicle braking force analysis according to an embodiment of the present invention. Detailed Implementation

[0043] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0044] The overall process of this invention is as follows: Figure 1 As shown, this invention includes parts such as vehicle driving state information acquisition, establishing an energy recovery trend model, adjusting the front and rear axle braking force distribution coefficients, and braking execution and system monitoring. Taking a two-axle rear-wheel-drive electric vehicle as an example, as... Figure 2 As shown, the specific steps are as follows:

[0045] S1. Obtain vehicle driving state information using an in-vehicle sensor system and a state estimator. This state information includes vehicle speed v, motor speed n, battery charge (SOC), and vehicle acceleration a. V The system collects parameter information and transmits this status information to the energy recovery trend depletion judgment module and the control module.

[0046] S2. The energy recovery trend decline judgment module establishes an energy recovery trend model based on the received data: calculating the regenerative braking power P at the current moment. r By analyzing consecutive Np Regenerative braking energy E within a time interval Δt r Curve fitting is performed, the slope k of the fitted energy recovery curve is calculated, and a trend decline threshold k0 is set. If k ≤ k0, the energy recovery trend decline state is determined, and a signal is sent to the control module. Otherwise, the vehicle continues the normal regenerative braking control process.

[0047] S21. First, calculate the regenerative braking power P at the current moment. r The calculation formula is as follows:

[0048]

[0049] In the formula, η m T represents the power generation efficiency of the motor. m The regenerative braking torque of the motor is expressed as:

[0050]

[0051] In the formula, T N P is the rated torque of the motor. n n is the power of the motor. r n is the actual speed of the motor. n This is the rated speed of the motor.

[0052] S22, By analyzing continuous N p The regenerative braking energy E within a time interval Δt (e.g., data is collected every 0.1s) r Perform curve fitting, E r for

[0053]

[0054] The energy recovery curve can be obtained by fitting using the least squares method, and its slope can be calculated.

[0055] S23. Set the trend decline threshold k0. If |k|≤k0, it is determined to be an energy recovery trend decline state, and a signal is sent to the control module to proceed to step S4. Otherwise, the vehicle continues the normal regenerative braking control process and proceeds to step S3.

[0056] When the slope k approaches zero, it indicates that the energy recovery trend is about to decline. Therefore, a trend decline threshold k0 is set. If |k|≤k0, the energy recovery trend decline is identified, and a signal is sent to the control module. If the threshold is not reached, the vehicle continues the normal regenerative braking control process.

[0057] During braking, the power battery, acting as an energy storage device, performs regenerative braking to recover energy. However, under the following circumstances, the regenerative braking control mode is not entered, and the determination of whether a trend of energy depletion has occurred is not performed:

[0058] If the battery's State of Charge (SOC) is already high, failing to exit regenerative braking mode will lead to overcharging, increasing battery heat and stress, and consequently affecting its safety and lifespan. To ensure the safety of the power battery and extend its lifespan, regenerative braking energy recovery will cease when the SOC exceeds a specific threshold. The threshold selected in this invention is the State of Charge (SOC). max =0.95, meaning that regenerative braking energy recovery stops when the State of Charge (SOC) reaches or exceeds 95%. Therefore, the regenerative braking torque correction is as follows:

[0059]

[0060] Furthermore, to ensure the stability and reliability of the braking effect, regenerative braking is not performed when the vehicle speed v is low; generally, v is set to a certain value. min =20km / h.

[0061] S3. The vehicle continues the normal regenerative braking control process and proceeds to step S5.

[0062] If the slope k does not reach the threshold, and the vehicle continues the normal regenerative braking control process, the vehicle's braking force distribution coefficient is a fixed value set at the factory. The control module determines the appropriate ratio of regenerative braking to mechanical braking based on the current operating conditions and executes the braking operation through the execution module. During the normal regenerative braking phase, based on the vehicle's speed and braking requirements, for example, when driving at low speeds and applying light braking, a larger proportion of regenerative braking is preferentially used.

[0063] S4. Entering the trend of brake failure state, by adjusting the front and rear axle braking force distribution coefficients of the vehicle, taking into account the vehicle status and making full use of the ground adhesion conditions, the braking performance is guaranteed while meeting the recovery efficiency.

[0064] When the vehicle enters a state of declining braking force, the braking force provided by the electric motor decreases. Blindly applying mechanical braking force can cause changes in the driver's brake pedal pressure, leading to misoperation. Directly cutting off the electric motor's power and using hydraulic braking force will reduce energy recovery efficiency. However, by adjusting the braking force distribution coefficient between the front and rear axles of the vehicle, considering the vehicle's condition, and making full use of ground adhesion conditions, it is possible to meet recovery efficiency while ensuring braking performance.

[0065] like Figure 3 As shown, during vehicle braking, the torque balance analysis of the entire vehicle and the front and rear wheel contact points yields the following results:

[0066]

[0067] In the formula, F Zf and F Zr ρ represents the normal force on the front and rear wheels, respectively; a and b represent the horizontal distances from the front and rear axles to the center of mass, respectively; L represents the distance between the front and rear axles; G represents the vehicle's weight; du / dt represents the vehicle's deceleration; h represents the vehicle's acceleration. g The height of the vehicle from the ground to its center of mass is z; the braking intensity is defined as the vehicle's deceleration a. V The ratio of the gravitational acceleration g to the acceleration due to gravity g, that is:

[0068]

[0069] During braking, if the braking force is large enough, both the front and rear wheels will lock up, resulting in a skidding phenomenon. At this time, the total braking force F Xb =Gμ, and du / dt = μg (μ is the road surface adhesion coefficient), then equations (4) and (5) can be written as follows:

[0070]

[0071] According to equations (4) to (8), as the braking intensity increases, the normal reaction force F of the front wheel increases. Zf Increase the normal reaction force F of the rear wheel Zr Reduced. When the braking intensity approaches the road surface adhesion coefficient, the front and rear wheels lock up and skid, and the vehicle can provide maximum braking force.

[0072] To achieve the required braking force, the braking system applies braking force to both the front and rear axles simultaneously. The distribution ratio is typically determined by comparing the braking force applied to the front axle with the total braking force, denoted by β.

[0073]

[0074] In the formula, F μ F is the total braking force of the vehicle's brakes. μ1 For the braking force of the front axle brake; F μ2 This provides braking force for the rear axle brake.

[0075] When the driver applies the brakes, if the front wheels are close to locking up, or if both the front and rear wheels are close to locking up, the braking force applied by the front wheel brakes is equal to the braking force F provided by the road surface to the front wheels. Xb1 Therefore, the following relationship holds:

[0076]

[0077] Similarly, when the rear wheels are close to locking or both the front and rear wheels are close to locking, the braking force F provided by the road surface to the rear wheels can be calculated. Xb2 :

[0078]

[0079] When a car applies braking force to produce a certain deceleration, the key to preventing wheel lock-up is that the braking force must not exceed the adhesion provided by the wheels. If the braking force exceeds the road adhesion, the wheels may lock up, leading to loss of control. Therefore, when the coefficient of adhesion between the car and the road surface is close to or greater than the braking intensity, it means that the road surface provides sufficient grip to support the braking force, thus preventing wheel lock-up. At this point, the road surface adhesion conditions are fully utilized, and the car's braking force distribution is more rational. To quantify the degree of utilization of road surface adhesion conditions, the concept of the coefficient of adhesion φ is introduced. i

[0080]

[0081] In the formula, F Xbi Let F be the ground braking force acting on the i-th axis of the car. Zi Let be the normal reaction force exerted by the ground on the i-th axis.

[0082] The following are the coefficients of adhesion for the front and rear wheels when either the front or rear wheels lock up prematurely or when both wheels lock up simultaneously:

[0083]

[0084] In the formula, φ f and φ r These are the coefficients of adhesion for the front and rear wheels, respectively. When the coefficient of adhesion is close to the braking intensity, the road surface adhesion conditions can be utilized more effectively, thereby achieving a more reasonable distribution of braking force.

[0085] To ensure the safety of vehicle braking, the brake force distribution must meet ECE regulations:

[0086] (1) Within the braking intensity range of z = 0.15 to 0.8, the front axle should utilize a greater coefficient of adhesion than the rear axle.

[0087] (2) Within the range of road surface adhesion coefficient of 0.2 to 0.8, the braking strength satisfies: z≥0.1+0.85(μ-0.2);

[0088] In the ECE regulations, clause (1) restricts the stability of the braking direction during vehicle braking, and clause (2) imposes certain constraints on vehicle braking efficiency. The following inequality constraint conditions can be obtained. Substituting μ = 0.2 and μ = 0.8 into z ≥ 0.1 + 0.85(μ - 0.2), we obtain that the range of z is 0.1 ≤ z ≤ 0.61. At this point, the coefficient of friction for the front and rear wheels is:

[0089]

[0090] When the braking intensity is 0.15≤z≤0.8, the utilization coefficient of the front and rear wheels meets the following condition:

[0091] φ f ≥φ r (16)

[0092] Substituting equations (13) to (14) into equations (15) and (16), we obtain a system of inequalities:

[0093]

[0094] Under ECE regulations, the traction utilization factor of the front wheels is always greater than that of the rear wheels, thus ensuring braking stability.

[0095] For ideal braking force distribution, both the front and rear wheels reach their lock-up limits simultaneously, resulting in the front and rear wheels having the same coefficient of friction. Therefore, the braking force distribution between the front and rear wheels follows the following relationship:

[0096]

[0097] The braking force distribution curve described by equation (18) is the I-curve, representing the ideal braking force distribution curve. During vehicle braking, it is unsafe for the rear wheels to lock up first. If the braking force distribution is within the range above the I-curve, the rear wheels will lock up first. Therefore, the braking force should be distributed within the range below the I-curve to ensure braking safety.

[0098]

[0099] The constraints on the braking force distribution ratio are:

[0100]

[0101] Simultaneously, during braking, the utilization coefficient of the wheels must be lower than the road surface adhesion coefficient. Furthermore, according to equation (19), the utilization coefficient of the front wheels should be greater than that of the rear wheels. Therefore, the following only considers the constraint of the front wheel utilization coefficient, i.e., the front wheel utilization coefficient should be less than the road surface adhesion coefficient.

[0102] φ f <μ (21)

[0103] The constraints for obtaining the braking force distribution ratio are as follows:

[0104]

[0105] Therefore, in order to optimize the braking force distribution ratio, equations (17), (20), and (22) are used as constraints to solve the braking performance optimization problem when the energy recovery of the electric vehicle is in a state of near-fading. The optimization objectives are as follows:

[0106] F target =min{(φ f -α m z) 2 +(φ r -α m z) 2} (twenty three)

[0107] Where, α m This is a proportionality coefficient, indicating that partial braking energy recovery is carried out to a certain extent while ensuring braking stability.

[0108] During braking, the total braking force in an electric vehicle is:

[0109]

[0110] Among them, F Xb For the total braking force, F bf For front axle braking force, F br For rear axle braking force, F reg For regenerative braking force of the motor, F hvd Provides hydraulic braking force for the front axle.

[0111] Based on the calculated optimal braking force distribution ratio, the rear axle braking force is calculated according to equation (4) as follows:

[0112] F br =F reg +F hvd =(1-β)F Xb (25)

[0113]

[0114] Among them, i g For the gear ratio of the transmission, i o The transmission ratio of the main reducer, η t Let r be the mechanical efficiency of the transmission system and the wheel radius.

[0115] Therefore, when the energy recovery of an electric vehicle is in a state of declining trend, the braking safety problem caused by the reduction in braking force can be avoided by adjusting the braking force distribution coefficient between the front and rear axles of the vehicle without changing the existing electric motor power.

[0116] S5. Braking Execution and System Monitoring: The execution module executes the instructions from the control module and continuously monitors the vehicle's status information.

[0117] The execution module precisely controls the braking hydraulic system and the generator state of the motor according to the instructions of the control module, ensuring smooth vehicle deceleration and successful energy recovery. Throughout the braking process, various vehicle parameters are continuously monitored, and the control strategy is adjusted promptly if any abnormalities are detected. This ensures that electric vehicles can more effectively utilize regenerative braking under different braking conditions, improving energy efficiency and ensuring the stability of braking performance.

[0118] Finally, it should be noted that the above control method can be converted into software program instructions. It can be implemented using a control system including a processor and memory, or it can be implemented using computer instructions stored in a non-transitory computer-readable storage medium. The integrated unit implemented as a software functional unit can be stored in a computer-readable storage medium. This software functional unit, stored in a storage medium, includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0119] In summary, the regenerative braking optimization method and system based on the judgment of energy recovery trend decline, as described above, has the following beneficial effects:

[0120] (1) This invention achieves refined monitoring and prediction of the trend of regenerative braking energy recovery by judging whether the energy recovery of electric vehicles has reached the trend of decline. When the trend of decline is determined, the front and rear axle braking force distribution coefficients of electric vehicles will be dynamically adjusted, thereby maximizing the recovery of energy while ensuring the stability of braking performance. The execution module strictly follows the instructions of the control module to precisely control the braking hydraulic system and the power generation state of the motor, ensuring that the vehicle decelerates smoothly and the energy recovery process proceeds smoothly. During the entire braking process, the modules work together to effectively overcome the problems of existing electric vehicle regenerative braking in terms of energy recovery efficiency, braking comfort, braking force distribution and control.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit it; although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A regenerative braking optimization method based on energy recovery trend decline judgment, characterized in that, include: S1. Obtain vehicle driving state information using in-vehicle sensor systems and state estimators, and transmit the state information to the energy recovery trend decline judgment module and control module. The state information includes motor speed n. r And vehicle acceleration a V ; S2. The energy recovery trend decline judgment module establishes an energy recovery trend model based on the received data: calculating the regenerative braking power P at the current moment. r By analyzing consecutive N p Regenerative braking energy E within a time interval Δt r Perform curve fitting, calculate the slope k of the fitted energy recovery curve, set the trend decline threshold k0, if k≤k0, determine the energy recovery trend decline state, send a signal to the control module, and proceed to step S4; otherwise, proceed to step S3. S3. The control module controls the vehicle to continue the normal regenerative braking control process and proceeds to step S5. S4. When the vehicle enters a tendency to decelerate, the control module, without changing the existing electric motor's power, adjusts the front-to-rear axle braking force distribution coefficient, taking into account the vehicle's condition and fully utilizing ground adhesion conditions, to ensure braking performance while maintaining recovery efficiency. The constraints of the front-to-rear axle braking force distribution coefficient include: ECE regulations: Constraints of the ideal braking force distribution curve: Constraints on the coefficient of adhesion of the road surface: Solve the braking performance optimization problem of an electric vehicle when its energy recovery is nearing a decline state, with the optimization objective being: Based on the calculated optimal braking force distribution coefficient, the rear axle braking force is calculated as follows: F br =F reg +F hvd =(1-β)F Xb In the formula, β is the front axle braking force distribution coefficient, a and b are the horizontal distances from the front and rear axles to the center of gravity, respectively, L is the distance between the front and rear axles, and h is the horizontal distance between the front and rear axles. g Let z be the height from the ground to the center of mass, and z be the braking intensity, defined as the vehicle acceleration a. V The ratio of α to the gravitational acceleration g. m φ is a proportionality coefficient, representing a moderate amount of regenerative braking energy recovery while ensuring braking stability. f and φ r These are the coefficients of adhesion for the front and rear wheels, respectively, where μ is the road surface adhesion coefficient, and F is the coefficient of adhesion for the front and rear wheels. Xb For the total braking force, F br For rear axle braking force, F reg For regenerative braking force of the motor, F hvd For front axle hydraulic braking force, i g For the gear ratio of the transmission, i o The transmission ratio of the main reducer, η t Let r be the mechanical efficiency of the transmission system and the wheel radius. S5. The execution module executes the instructions from the control module and continuously monitors the vehicle's status information.

2. The regenerative braking optimization method based on energy recovery trend depletion judgment according to claim 1, characterized in that, In S2, the calculation of the regenerative braking power P at the current moment... r include: In the formula, η m T represents the power generation efficiency of the motor. m T is the regenerative braking torque of the motor. N P is the rated torque of the motor. n n is the power of the motor. r n is the actual speed of the motor. n This is the rated speed of the motor.

3. The regenerative braking optimization method based on energy recovery trend decline judgment according to claim 1, characterized in that, In S2, the regenerative braking energy E r for: The slope k is:

4. The regenerative braking optimization method based on energy recovery trend decline judgment according to claim 1, characterized in that, In S3, when the vehicle continues the normal regenerative braking control process, the vehicle braking force distribution coefficient is a fixed value set at the factory. The control module determines the appropriate ratio of regenerative braking to mechanical braking based on the current operating conditions and executes the braking operation through the execution module.

5. The regenerative braking optimization method based on energy recovery trend depletion judgment according to claim 1, characterized in that, The status information also includes vehicle speed v and battery charge state of charge (SOC). When the battery charge SOC exceeds a set threshold SOC... max When the vehicle speed v is below a set threshold v, regenerative braking will cease. min At that time, regenerative braking will not be performed.

6. A regenerative braking optimization system based on energy recovery trend decline judgment, characterized in that, The regenerative braking optimization method based on energy recovery trend decline judgment as described in any one of claims 1-5 includes: an in-vehicle sensor system, a state estimator, an energy recovery trend decline judgment module, a control module, and an execution module.

7. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to perform the method as described in any one of claims 1 to 5.

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