Electronic mechanical braking system control method suitable for electric automobile

Abstract

The invention discloses an electronic mechanical braking system control method suitable for an electric vehicle. A driving state acquisition module, an electronic mechanical braking evaluation calculation module, a braking force calculation distribution module and an electronic mechanical braking state division module are included. The invention aims to accurately control the electronic mechanical braking process of the electric vehicle through a driving state acquisition module, an electronic mechanical braking evaluation calculation module, a braking force calculation distribution module and an electronic mechanical braking state division module.

Description

Technical Field

[0001] The invention relates to a control method of an electronic mechanical brake system suitable for an electric vehicle. Background Art

[0002] With the development of automobile electrification and intelligent technology, the new brake system based on electronic mechanical braking, as a wire-controlled decoupled braking system, can not only meet the demand for brake pedal feel, but also achieve continuous and precise control of braking force, and can effectively take into account braking economy, braking safety and braking comfort. However, most of the current research on electronic mechanical braking systems only involves aspects such as clamping force estimation and precise control of clamping force, ignoring the influence of brake disc temperature on the electronic mechanical braking system, but the brake disc temperature is crucial to the clamping force control of the electronic mechanical braking system. Therefore, in order to improve the above problems, the present invention proposes a control method for an electronic mechanical braking system suitable for electric vehicles. Summary of the invention

[0003] The purpose of the present invention is to provide an electronic mechanical brake system control method suitable for electric vehicles to solve the problems faced in the above-mentioned background technology.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solutions: A control method for an electronic mechanical brake system applicable to an electric vehicle comprises a driving state acquisition module, an electronic mechanical brake evaluation calculation module, a braking force calculation and distribution module and an electronic mechanical brake state division module;

[0005] The driving state acquisition module is used to collect basic information during the vehicle driving process, including the driver's brake pedal opening signal Z t , Brake pedal opening rate signal Z tv , the total mass of the electric vehicle m, the driving speed of the electric vehicle V, the road adhesion coefficient μ road , the longitudinal speed of each wheel of the vehicle V xi , i = fl, fr, rl, rr, respectively represents the left front wheel, right front wheel, left rear wheel and right rear wheel, the vehicle's wheel brake disc temperature Temp i , i=fl,fr,rl,rr、ambient temperature Temp e , Brake caliper contact point corresponding to the minimum clamping force F nmin , the contact point between the brake and the brake disc corresponds to the ball screw displacement S L , the displacement of the ball screw of each wheel brake of the vehicle S i , i = fl, fr, rl, rr;

[0006] The electronic mechanical brake evaluation calculation module is used to collect various data to calculate the corresponding influencing factors and the expected total braking force, including:

[0007] The driver's operating awareness evaluation factor K1 is calculated according to the following formula:

[0008]

[0009] Among them, α1, α2, α3, α4, and α5 represent weight coefficients;

[0010] k 11 It represents the driving style coefficient, which reflects the driver's overall tendency towards vehicle operation during driving. When the style is conservative, k 11 =0.7, the operation is relatively stable and cautious, and sudden acceleration and braking are reduced. When the driving style is standard, k 11 =1.0, the operation is relatively balanced, neither aggressive nor too conservative. When the driver's style is aggressive, k 11 =1.5, intense operation, frequent sudden acceleration and braking;

[0011] k 12 Indicates the driving mode coefficient, which reflects the vehicle driving mode selected by the driver. When the mode is economic mode, k 12 =0.5, the driver's operation is relatively stable, energy-saving, and the operating awareness is strong. When the mode is standard mode, k 12 =1.0, the driver's operation is relatively balanced and adaptable to various driving environments. When the mode is sports mode, k 12 =1.5, the driver tends to accelerate and brake aggressively, and the operating awareness may be low;

[0012] k 13 It represents the environmental complexity coefficient, which reflects the complexity of the environment in which the driver is in during driving. When the driver is in a simple environment, k 13 = 0.2, smooth traffic, good weather, simple road conditions, when in a medium environment, k 13 =0.5, the traffic is congested or the weather is unstable, and the driving environment is complex. When in a complex environment, k 13 =1.0, dense traffic, crowded roads, and bad weather greatly increase the stress on drivers;

[0013] k 14 represents the risk perception coefficient, which reflects the driver's sensitivity to potential risks. When the risk perception is low, k 14 =0.2, the driver pays less attention to the surrounding risks and may ignore potential dangers. When the risk perception is medium, k 14 =0.5, the driver can identify and respond to certain risks, high risk perception, k 14 =1.0, the driver is highly alert and responds quickly to surrounding risks;

[0014] k 15 Indicates the fatigue coefficient, reflecting the driver's physical fatigue level. When the driver is in low fatigue, k 15 = 0.2, the driver is energetic and responsive, when in moderate fatigue, k 15 =0.5, the driver feels a certain degree of fatigue and his reaction speed decreases. When the driver is in a state of high fatigue, k 25 =1.0, the driver feels very tired, which may affect the operating awareness and reaction ability.

[0015] The electronic mechanical brake evaluation calculation module calculates the average wear factor K2 of the brake disc according to the following formula:

[0016]

[0017]

[0018] Among them, p i represents the brake disc wear coefficient, i = fl, fr, rl, rr, respectively representing the left front wheel, right front wheel, left rear wheel and right rear wheel, V represents the driving speed of the electric vehicle, V xi Indicates the longitudinal speed of each wheel of the vehicle, i = fl, fr, rl, rr, Temp i Indicates the temperature of the brake disc of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e represents the ambient temperature, and C1, C2, C3, and C4 represent weight coefficients.

[0019] The electronic mechanical brake evaluation calculation module establishes a brake deceleration model when the vehicle brakes, and the pedal brake intensity Z of the electric vehicle x Satisfy the formula:

[0020]

[0021] Among them, Z t Indicates the brake pedal opening signal, Z tv represents the brake pedal opening rate change signal, and w1, w2, w3, w4, and w5 represent weight coefficients.

[0022] The electronic mechanical brake evaluation calculation module calculates the expected total braking force Fb according to the following formula: Total :

[0023]

[0024] Where m represents the total mass of the electric vehicle, g represents the acceleration of gravity, and Z xrepresents the pedal braking strength of the electric vehicle, K1 represents the average wear factor of the brake disc, K2 represents the driver's operation awareness evaluation factor, and β1 and β2 represent weight coefficients.

[0025] The braking force calculation and distribution module specifically includes a brake friction coefficient calculation unit and a four-wheel braking force distribution unit:

[0026] The brake friction coefficient calculation unit is used to calculate the brake disc wear coefficient p according to the brake i , i = fl, fr, rl, rr, the vehicle's wheel brake disc temperature Temp i , i = fl, fr, rl, rr and ambient temperature Temp e Calculate the friction coefficient μ of the brake friction pad i :

[0027]

[0028] Among them, p i represents the brake disc wear coefficient, i = fl, fr, rl, rr, respectively representing the left front wheel, right front wheel, left rear wheel and right rear wheel, Temp i Indicates the temperature of the brake disc of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e represents the ambient temperature, D1 and D2 represent the weight coefficients;

[0029] Four-wheel brake force distribution unit is used to adjust the friction coefficient of the brake friction pad according to the i and the expected total braking force Fb Total Distributes four-wheel braking force, including:

[0030] Calculate the vertical load F on the front axle during braking according to the following formula: zf Vertical load F on the rear axle zr :

[0031]

[0032] Where m represents the total mass of the electric vehicle, g represents the acceleration of gravity, and Z x represents the pedal braking strength of the electric vehicle, a represents the distance between the front axle and the center of mass, b represents the distance between the rear axle and the center of mass, L represents the distance between the front axle and the rear axle, and h represents the distance between the front axle and the rear axle. g represents the height of the centroid;

[0033] Calculate the front and rear axle braking force distribution ratio β according to the following formula fr :

[0034]

[0035] Among them, F zfIndicates the vertical load on the front axle, F zr represents the vertical load on the rear axle, a represents the distance between the front axle and the center of mass, b represents the distance between the rear axle and the center of mass, and Z x Indicates the pedal braking strength of electric vehicles, h g represents the height of the centroid;

[0036] Calculate the target braking torque T of each front and rear wheel according to the following formula bdi :

[0037]

[0038] Among them, β fr Indicates the front and rear axle braking force distribution ratio, Fb Total represents the expected total braking force, R represents the wheel rolling radius, μ road Represents the road adhesion coefficient, T bdfl 、T bdfr 、T bdrl 、T bdrr Respectively represent the left front wheel target braking torque, the right front wheel target braking torque, the left rear wheel target braking torque and the right rear wheel target braking torque;

[0039] Calculate the target clamping force F of the front and rear wheel electromechanical brake system according to the following formula cli :

[0040]

[0041] Among them, T bdi represents the target braking torque, μ i Indicates the friction coefficient of the brake friction pad, i = fl, fr, rl, rr, R b Indicates the brake disc radius.

[0042] The electronic mechanical brake state classification module specifically includes a brake disc contact detection unit and an electronic mechanical brake system control unit:

[0043] Brake disc contact detection unit, used to correspond the ball screw displacement S according to the contact point between the brake and the brake disc L , the displacement of the ball screw of each wheel brake of the vehicle S i , i = fl, fr, rl, rr detect the state of the electronic mechanical brake system and calculate the brake clamping force F ni :

[0044]

[0045] Among them, a1, a2, a3, a4, and a5 represent the fitting coefficients, and x irepresents the lateral displacement after the brake caliper contacts the brake disc, i = fl, fr, rl, rr, when S is satisfied i ≤S L When x i =0, when S i >S L When x i =S L -S i .

[0046] The electronic mechanical brake state classification module and the electronic mechanical brake system control unit are used to determine the minimum clamping force F corresponding to the contact point of the brake caliper. nmin , Brake clamping force F ni and target clamping force F cli , determine the mode of the electronic mechanical brake system, including the brake gap elimination stage, the clamping force following stage, and the brake gap formation stage;

[0047] When F is satisfied cli >0 and F ni <F nmin When the electronic mechanical braking mode is in the brake clearance elimination stage, the maximum speed n that the output brake motor can provide is max ;

[0048] When F is satisfied cli ≥0 and F ni >F nmin When the electronic mechanical braking mode is in the clamping force following stage, according to the brake clamping force F ni and target clamping force F cli , using the pid controller to follow the target clamping force;

[0049] When F is satisfied cli =0 and F ni <F nmin When the electronic mechanical braking mode is in the brake gap formation stage, the maximum speed n that the output brake motor can provide is max , and according to the displacement S of the ball screw of each wheel brake of the vehicle i , use pid controller to control S i Return to the point of maximum braking clearance.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. A control method for an electronic mechanical braking system suitable for an electric vehicle comprises a driving state acquisition module, an electronic mechanical braking evaluation calculation module, a braking force calculation and distribution module and an electronic mechanical braking state division module;

[0052] 2. The braking force calculation and distribution module of the present invention includes a brake friction pad friction coefficient calculation unit and a four-wheel braking force distribution unit, which calculates the brake friction pad friction coefficient μ i , to accurately determine the desired brake clamping force and improve braking precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention will be further described below in conjunction with the accompanying drawings:

[0054] Figure 1 This is a framework diagram of an electronic mechanical braking system control method suitable for electric vehicles proposed by the present invention. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below based on the accompanying drawings and specific embodiments.

[0056] like Figure 1 As shown, the present invention is an electronic mechanical brake system control method suitable for electric vehicles, including a driving state acquisition module, an electronic mechanical brake evaluation calculation module, a braking force calculation distribution module and an electronic mechanical brake state division module;

[0057] The driving state acquisition module is used to collect basic information during the vehicle driving process, including the driver's brake pedal opening signal Z t , Brake pedal opening rate signal Z tv , the total mass of the electric vehicle m, the driving speed of the electric vehicle V, the road adhesion coefficient μ road , the longitudinal speed of each wheel of the vehicle V xi , i = fl, fr, rl, rr, respectively represents the left front wheel, right front wheel, left rear wheel and right rear wheel, the vehicle's wheel brake disc temperature Temp i , i=fl,fr,rl,rr、ambient temperature Temp e , Brake caliper contact point corresponding to the minimum clamping force F nmin , the contact point between the brake and the brake disc corresponds to the ball screw displacement S L , the displacement of the ball screw of each wheel brake of the vehicle S i , i = fl, fr, rl, rr;

[0058] The electronic mechanical brake evaluation calculation module is used to collect various data to calculate the corresponding influencing factors and the expected total braking force, including:

[0059] The driver's operating awareness evaluation factor K1 is calculated according to the following formula:

[0060]

[0061] Among them, α1, α2, α3, α4, and α5 represent weight coefficients;

[0062] k 11 It represents the driving style coefficient, which reflects the driver's overall tendency towards vehicle operation during driving. When the style is conservative, k 11 =0.7, the operation is relatively stable and cautious, and sudden acceleration and braking are reduced. When the driving style is standard, k 11 =1.0, the operation is relatively balanced, neither aggressive nor too conservative. When the driver's style is aggressive, k 11 =1.5, intense operation, frequent sudden acceleration and braking;

[0063] k 12 Indicates the driving mode coefficient, which reflects the vehicle driving mode selected by the driver. When the mode is economic mode, k 12 =0.5, the driver's operation is relatively stable, energy-saving, and the operating awareness is strong. When the mode is standard mode, k 12 =1.0, the driver's operation is relatively balanced and adaptable to various driving environments. When the mode is sports mode, k 12 =1.5, the driver tends to accelerate and brake aggressively, and the operating awareness may be low;

[0064] k 13 It represents the environmental complexity coefficient, which reflects the complexity of the environment in which the driver is in during driving. When the driver is in a simple environment, k 13 = 0.2, smooth traffic, good weather, simple road conditions, when in a medium environment, k 13 =0.5, the traffic is congested or the weather is unstable, and the driving environment is complex. When in a complex environment, k 13 =1.0, dense traffic, crowded roads, and bad weather greatly increase the stress on drivers;

[0065] k 14 represents the risk perception coefficient, which reflects the driver's sensitivity to potential risks. When the risk perception is low, k 14 =0.2, the driver pays less attention to the surrounding risks and may ignore potential dangers. When the risk perception is medium, k 14 =0.5, the driver can identify and respond to certain risks, high risk perception, k 14 =1.0, the driver is highly alert and responds quickly to surrounding risks;

[0066] k 15 Indicates the fatigue coefficient, reflecting the driver's physical fatigue level. When the driver is in low fatigue, k 15 = 0.2, the driver is energetic and responsive, when in moderate fatigue, k 15=0.5, the driver feels a certain degree of fatigue and his reaction speed decreases. When the driver is in a state of high fatigue, k 25 =1.0, the driver feels very tired, which may affect the operating awareness and reaction ability.

[0067] The electronic mechanical brake evaluation calculation module calculates the average wear factor K2 of the brake disc according to the following formula:

[0068]

[0069] Among them, p i represents the brake disc wear coefficient, i = fl, fr, rl, rr, respectively representing the left front wheel, right front wheel, left rear wheel and right rear wheel, V represents the driving speed of the electric vehicle, V xi Indicates the longitudinal speed of each wheel of the vehicle, i = fl, fr, rl, rr, Temp i Indicates the temperature of the brake disc of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e represents the ambient temperature, and C1, C2, C3, and C4 represent weight coefficients.

[0070] The electronic mechanical brake evaluation calculation module establishes a brake deceleration model when the vehicle brakes, and the pedal brake intensity Z of the electric vehicle x Satisfy the formula:

[0071]

[0072] Among them, Z t Indicates the brake pedal opening signal, Z tv represents the brake pedal opening rate change signal, and w1, w2, w3, w4, and w5 represent weight coefficients.

[0073] The electronic mechanical brake evaluation calculation module calculates the expected total braking force Fb according to the following formula: Total :

[0074]

[0075] Where m represents the total mass of the electric vehicle, g represents the acceleration of gravity, and Z x represents the pedal braking strength of the electric vehicle, K1 represents the average wear factor of the brake disc, K2 represents the driver's operation awareness evaluation factor, and β1 and β2 represent weight coefficients.

[0076] The braking force calculation and distribution module specifically includes a brake friction coefficient calculation unit and a four-wheel braking force distribution unit:

[0077] The brake friction coefficient calculation unit is used to calculate the brake disc wear coefficient p according to the brake i, i = fl, fr, rl, rr, the vehicle's wheel brake disc temperature Temp i , i = fl, fr, rl, rr and ambient temperature Temp e Calculate the friction coefficient μ of the brake friction pad i :

[0078]

[0079] Among them, p i represents the brake disc wear coefficient, i = fl, fr, rl, rr, respectively representing the left front wheel, right front wheel, left rear wheel and right rear wheel, Temp i Indicates the temperature of the brake disc of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e represents the ambient temperature, D1 and D2 represent the weight coefficients;

[0080] Four-wheel brake force distribution unit is used to adjust the friction coefficient of the brake friction pad according to the i and the expected total braking force Fb Total Distributes four-wheel braking force, including:

[0081] Calculate the vertical load F on the front axle during braking according to the following formula: zf Vertical load F on the rear axle zr :

[0082]

[0083] Where m represents the total mass of the electric vehicle, g represents the acceleration of gravity, and Z x represents the pedal braking strength of the electric vehicle, a represents the distance between the front axle and the center of mass, b represents the distance between the rear axle and the center of mass, L represents the distance between the front axle and the rear axle, and h represents the distance between the front axle and the rear axle. g represents the height of the centroid;

[0084] Calculate the front and rear axle braking force distribution ratio β according to the following formula fr :

[0085]

[0086] Among them, F zf Indicates the vertical load on the front axle, F zr represents the vertical load on the rear axle, a represents the distance between the front axle and the center of mass, b represents the distance between the rear axle and the center of mass, and Z x Indicates the pedal braking strength of electric vehicles, h g represents the height of the centroid;

[0087] Calculate the target braking torque T of each front and rear wheel according to the following formula bdi :

[0088]

[0089] Among them, β fr Indicates the front and rear axle braking force distribution ratio, Fb Total represents the expected total braking force, R represents the wheel rolling radius, μ road Represents the road adhesion coefficient, T bdfl 、T bdfr 、T bdrl 、T bdrr Respectively represent the left front wheel target braking torque, the right front wheel target braking torque, the left rear wheel target braking torque and the right rear wheel target braking torque;

[0090] Calculate the target clamping force F of the front and rear wheel electromechanical brake system according to the following formula cli :

[0091]

[0092] Among them, T bdi represents the target braking torque, μ i Indicates the friction coefficient of the brake friction pad, i = fl, fr, rl, rr, R b Indicates the brake disc radius.

[0093] The electronic mechanical brake state classification module specifically includes a brake disc contact detection unit and an electronic mechanical brake system control unit:

[0094] Brake disc contact detection unit, used to correspond the ball screw displacement S according to the contact point between the brake and the brake disc L , the displacement of the ball screw of each wheel brake of the vehicle S i , i = fl, fr, rl, rr detect the state of the electronic mechanical brake system and calculate the brake clamping force F ni :

[0095]

[0096] Among them, a1, a2, a3, a4, and a5 represent the fitting coefficients, and x i represents the lateral displacement after the brake caliper contacts the brake disc, i = fl, fr, rl, rr, when S is satisfied i ≤S L When x i =0, when S i >S L When x i =S L -S i .

[0097] The electronic mechanical brake state classification module and the electronic mechanical brake system control unit are used to determine the minimum clamping force F corresponding to the contact point of the brake caliper. nmin , Brake clamping force F ni and target clamping force F cli , determine the mode of the electronic mechanical brake system, including the brake gap elimination stage, the clamping force following stage, and the brake gap formation stage;

[0098] When F is satisfied cli >0 and F ni <F nmin When the electronic mechanical braking mode is in the brake clearance elimination stage, the maximum speed n that the output brake motor can provide is max ;

[0099] When F is satisfied cli ≥0 and F ni >F nmin When the electronic mechanical braking mode is in the clamping force following stage, according to the brake clamping force F ni and target clamping force F cli , using the pid controller to follow the target clamping force;

[0100] When F is satisfied cli =0 and F ni <F nmin When the electronic mechanical braking mode is in the brake gap formation stage, the maximum speed n that the output brake motor can provide is max , and according to the displacement S of the ball screw of each wheel brake of the vehicle i , use pid controller to control S i Return to the point of maximum braking clearance.

Claims

1. A control method for an electronic mechanical brake system of an electric vehicle, characterized in that: The Method Includes the following: Driving state acquisition module, electronic mechanical brake evaluation calculation module, braking force calculation distribution module and electronic mechanical brake state division module; The driving state acquisition module is used to collect basic information during the vehicle driving process, including the driver's brake pedal opening signal Z t , Brake pedal opening rate signal Z tv , the total mass of the electric vehicle m, the driving speed of the electric vehicle V, the road adhesion coefficient μ road , the longitudinal speed of each wheel of the vehicle V xi , i = fl, fr, rl, rr, respectively represents the left front wheel, right front wheel, left rear wheel and right rear wheel, the vehicle's wheel brake disc temperature Temp i , i=fl,fr,rl,rr、ambient temperature Temp e , Brake caliper contact point corresponding to the minimum clamping force F nmin , the contact point between the brake and the brake disc corresponds to the ball screw displacement S L , the displacement of the ball screw of each wheel brake of the vehicle S i , i = fl, fr, rl, rr; The electronic mechanical brake evaluation calculation module is used to collect various data to calculate the corresponding influencing factors and the expected total braking force, including: The driver's operating awareness evaluation factor K1 is calculated according to the following formula: Among them, α1, α2, α3, α4, and α5 represent weight coefficients; k 11 It represents the driving style coefficient, which reflects the driver's overall tendency towards vehicle operation during driving. When the style is conservative, k 11 =0.7, the operation is relatively stable and cautious, and sudden acceleration and braking are reduced. When the driving style is standard, k 11 =1.0, the operation is relatively balanced, neither aggressive nor too conservative. When the driver's style is aggressive, k 11 =1.5, intense operation, frequent sudden acceleration and braking; k 12 Indicates the driving mode coefficient, which reflects the vehicle driving mode selected by the driver. When the mode is economic mode, k 12 =0.5, the driver's operation is relatively stable, energy-saving, and the operating awareness is strong. When the mode is standard mode, k 12 =1.0, the driver's operation is relatively balanced and adaptable to various driving environments. When the mode is sports mode, k 12 =1.5, the driver tends to accelerate and brake aggressively, and the operating awareness may be low; k 13 It represents the environmental complexity coefficient, which reflects the complexity of the environment in which the driver is in during driving. When the driver is in a simple environment, k 13 = 0.2, smooth traffic, good weather, simple road conditions, when in a medium environment, k 13 =0.5, the traffic is congested or the weather is unstable, and the driving environment is complex. When in a complex environment, k 13 =1.0, dense traffic, crowded roads, and bad weather greatly increase the stress on drivers; k 14 represents the risk perception coefficient, which reflects the driver's sensitivity to potential risks. When the risk perception is low, k 14 =0.2, the driver pays less attention to the surrounding risks and may ignore potential dangers. When the risk perception is medium, k 14 =0.5, the driver can identify and respond to certain risks, high risk perception, k 14 =1.0, the driver is highly alert and responds quickly to surrounding risks; k 15 Indicates the fatigue coefficient, reflecting the driver's physical fatigue level. When the driver is in low fatigue, k 15 = 0.2, the driver is energetic and responsive, when in moderate fatigue, k 15 =0.5, the driver feels a certain degree of fatigue and his reaction speed decreases. When the driver is in a state of high fatigue, k 25 =1.0, the driver feels very tired, which may affect the operating awareness and reaction ability.

2. The method for controlling an electronic mechanical brake system of an electric vehicle according to claim 1, characterized in that: The electronic mechanical brake evaluation calculation module calculates the average wear factor K2 of the brake disc according to the following formula: Among them, p i represents the brake disc wear coefficient, i = fl, fr, rl, rr, respectively representing the left front wheel, right front wheel, left rear wheel and right rear wheel, V represents the driving speed of the electric vehicle, V xi Indicates the longitudinal speed of each wheel of the vehicle, i = fl, fr, rl, rr, Temp i Indicates the temperature of the brake disc of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e represents the ambient temperature, and C1, C2, C3, and C4 represent weight coefficients.

3. The method for controlling an electronic mechanical brake system of an electric vehicle according to claim 1, characterized in that: The electronic mechanical brake evaluation calculation module establishes a brake deceleration model when the vehicle brakes, and the pedal brake intensity Z of the electric vehicle x Satisfy the formula: Among them, Z t Indicates the brake pedal opening signal, Z tv represents the brake pedal opening rate change signal, and w1, w2, w3, w4, and w5 represent weight coefficients.

4. The method for controlling an electronic mechanical brake system of an electric vehicle according to claim 1, characterized in that: The electronic mechanical brake evaluation calculation module calculates the expected total braking force Fb according to the following formula: Total : Where m represents the total mass of the electric vehicle, g represents the acceleration of gravity, and Z x represents the pedal braking strength of the electric vehicle, K1 represents the average wear factor of the brake disc, K2 represents the driver's operation awareness evaluation factor, and β1 and β2 represent weight coefficients.

5. The method for controlling an electronic mechanical brake system of an electric vehicle according to claim 1, characterized in that: The braking force calculation and distribution module specifically includes a brake friction coefficient calculation unit and a four-wheel braking force distribution unit: The brake friction coefficient calculation unit is used to calculate the brake disc wear coefficient p according to the brake i , i = fl, fr, rl, rr, the vehicle's wheel brake disc temperature Temp i , i = fl, fr, rl, rr and ambient temperature Temp e Calculate the friction coefficient μ of the brake friction pad i : Among them, p i represents the brake disc wear coefficient, i = fl, fr, rl, rr, respectively representing the left front wheel, right front wheel, left rear wheel and right rear wheel, Temp i Indicates the temperature of the brake disc of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e represents the ambient temperature, D1 and D2 represent the weight coefficients; Four-wheel brake force distribution unit is used to adjust the friction coefficient of the brake friction pad according to the i and the expected total braking force Fb Total Distributes four-wheel braking force, including: Calculate the vertical load F on the front axle during braking according to the following formula: zf Vertical load F on the rear axle zr : Where m represents the total mass of the electric vehicle, g represents the acceleration of gravity, and Z x represents the pedal braking strength of the electric vehicle, a represents the distance between the front axle and the center of mass, b represents the distance between the rear axle and the center of mass, L represents the distance between the front axle and the rear axle, and h represents the distance between the front axle and the rear axle. g represents the height of the centroid; Calculate the front and rear axle braking force distribution ratio β according to the following formula fr : Among them, F zf Indicates the vertical load on the front axle, F zr represents the vertical load on the rear axle, a represents the distance between the front axle and the center of mass, b represents the distance between the rear axle and the center of mass, and Z x Indicates the pedal braking strength of electric vehicles, h g represents the height of the centroid; Calculate the target braking torque T of each front and rear wheel according to the following formula bdi : Among them, β fr Indicates the front and rear axle braking force distribution ratio, Fb Total represents the expected total braking force, R represents the wheel rolling radius, μ road Represents the road adhesion coefficient, T bdfl 、T bdfr 、T bdrl 、T bdrr Respectively represent the left front wheel target braking torque, the right front wheel target braking torque, the left rear wheel target braking torque and the right rear wheel target braking torque; Calculate the target clamping force F of the front and rear wheel electromechanical brake system according to the following formula cli : Among them, T bdi represents the target braking torque, μ i Indicates the friction coefficient of the brake friction pad, i = fl, fr, rl, rr, R b Indicates the brake disc radius.

6. The method for controlling an electronic mechanical brake system of an electric vehicle according to claim 1, characterized in that: The electronic mechanical brake state classification module specifically includes a brake disc contact detection unit and an electronic mechanical brake system control unit: Brake disc contact detection unit, used to correspond the ball screw displacement S according to the contact point between the brake and the brake disc L , the displacement of the ball screw of each wheel brake of the vehicle S i , i = fl, fr, rl, rr detect the state of the electronic mechanical brake system and calculate the brake clamping force F ni : Among them, a1, a2, a3, a4, and a5 represent the fitting coefficients, and x i represents the lateral displacement after the brake caliper contacts the brake disc, i = fl, fr, rl, rr, when S is satisfied i ≤S L When x i =0, when S i >S L When x i =S L -S i .

7. The method for controlling an electronic mechanical brake system of an electric vehicle according to claim 1, characterized in that: The electronic mechanical brake state classification module and the electronic mechanical brake system control unit are used to determine the minimum clamping force F corresponding to the contact point of the brake caliper. nmin , Brake clamping force F ni and target clamping force F cli , determine the mode of the electronic mechanical brake system, including the brake gap elimination stage, the clamping force following stage, and the brake gap formation stage; When F is satisfied cli >0 and F ni <F nmin When the electronic mechanical braking mode is in the brake clearance elimination stage, the maximum speed n that the output brake motor can provide is max ; When F is satisfied cli ≥0 and F ni >F nmin When the electronic mechanical braking mode is in the clamping force following stage, according to the brake clamping force F ni and target clamping force F cli , using the pid controller to follow the target clamping force; When F is satisfied cli =0 and F ni <F nmin When the electronic mechanical braking mode is in the brake gap formation stage, the maximum speed n that the output brake motor can provide max , and according to the displacement S of the ball screw of each wheel brake of the vehicle i , use pid controller to control S i Return to the point of maximum braking clearance.

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