A control method for an electromechanical braking system suitable for electric vehicles

Abstract

This invention discloses a control method for an electromechanical braking system suitable for electric vehicles, including a driving state acquisition module, an electromechanical braking evaluation and calculation module, a braking force calculation and allocation module, and an electromechanical braking state division module. The purpose of this invention is to accurately control the electromechanical braking process of electric vehicles through the driving state acquisition module, the electromechanical braking evaluation and calculation module, the braking force calculation and allocation module, and the electromechanical braking state division module.

Description

Technical Field

[0001] This invention relates to a control method for an electromechanical braking system suitable for electric vehicles. Background Technology

[0002] With the development of automotive electrification and intelligent technology, a novel braking system based on electromechanical braking, as a type of drive-by-wire decoupled braking system, not only meets the requirements of brake pedal feel but also achieves continuous and precise control of braking force, effectively balancing braking economy, braking safety, and braking comfort. However, current research on electromechanical braking systems mostly focuses on clamping force estimation and precise clamping force control, neglecting the impact of brake disc temperature on the electromechanical braking system, which is crucial for clamping force control. Therefore, to address the aforementioned issues, this invention proposes a control method for an electromechanical braking system suitable for electric vehicles. Summary of the Invention

[0003] The purpose of this invention is to provide a control method for an electromechanical braking system suitable for electric vehicles, so as to solve the problems faced in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a control method for an electromechanical braking system suitable for electric vehicles, comprising a driving state acquisition module, an electromechanical braking evaluation and calculation module, a braking force calculation and allocation module, and an electromechanical braking state division module;

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

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

[0007] Calculate the driver's operational awareness evaluation factor K1 using the following formula:

[0008]

[0009] Where α1, α2, α3, α4, and α5 represent weighting coefficients;

[0010] k 11 This represents the driving style coefficient, reflecting the driver's overall tendency in vehicle operation during driving. When the driving style is conservative, k... 11 =0.7, indicating relatively smooth and cautious operation, reducing sudden acceleration and braking. When the driving style is that of a standard driver, k 11 =1.0, the operation is relatively balanced, neither too aggressive nor too conservative. When the driving style is aggressive, k 11 =1.5, aggressive driving, frequent rapid acceleration and braking;

[0011] k 12 k represents the driving mode coefficient, reflecting the vehicle driving mode selected by the driver. When the mode is economy mode, k 12 =0.5, the driver's operation is relatively smooth and energy-efficient, and the driver's awareness of operation is strong. When the mode is standard mode, k 12 =1.0, the driver's operation is relatively balanced, adapting to various driving environments. When the mode is Sport mode, k 12 =1.5, the driver tends to accelerate and brake aggressively, and may have low operational awareness;

[0012] k 13 k represents the environmental complexity coefficient, reflecting the complexity of the environment in which the driver is driving. When in a simple environment, k... 13 =0.2, smooth traffic, good weather, simple road conditions, when in a moderate environment, k 13 =0.5, traffic is relatively congested or the weather is unstable, the driving environment is complex, and when in a complex environment, k 13 =1.0, heavy traffic, congested roads, and inclement weather greatly increase the stress on drivers;

[0013] k 14 k represents the risk perception coefficient, reflecting the driver's sensitivity to potential risks. When the risk perception is low, k... 14 =0.2, the driver pays less attention to surrounding risks and may ignore potential dangers. When the driver is in a state of moderate risk perception, k 14 =0.5, the driver is able to identify and deal with certain risks, high risk perception, k 14 =1.0, the driver is highly alert and reacts quickly to surrounding risks;

[0014] k 15 k represents the fatigue level coefficient, reflecting the driver's level of physical fatigue. When the driver is in a state of low fatigue, k... 15 =0.2, the driver is energetic and reacts quickly; when under moderate fatigue, k 15 =0.5, the driver is somewhat fatigued, and the reaction speed is reduced. When under high fatigue, k 25 =1.0, the driver is very tired, which may affect operational awareness and reaction ability.

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

[0016]

[0017]

[0018] Where, p i The wear coefficient of the brake disc is represented by i = fl, fr, rl, rr, which represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. V represents the speed of the electric vehicle. xi Representing the longitudinal velocities of each wheel of the vehicle, i = fl, fr, rl, rr, Temp i This represents the temperature of the brake discs of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e The ambient temperature is represented by C1, C2, C3, and C4, which represent weighting coefficients.

[0019] The electromechanical braking evaluation and calculation module establishes a braking deceleration model during vehicle braking, and the pedal braking intensity Z of the electric vehicle is calculated. x Satisfying the formula:

[0020]

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

[0022] The electromechanical braking evaluation and 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 due to gravity, and Z represents the acceleration due to gravity. xK1 represents the average wear factor of the brake disc, K2 represents the driver's operating awareness evaluation factor, and β1 and β2 represent weighting 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 based on the brake friction coefficient p of the brake. i i = fl, fr, rl, rr, the temperature of the brake discs of each wheel of the vehicle (Temp) i i = fl, fr, rl, rr and ambient temperature Temp e Calculate the friction coefficient μ of the brake friction pads i :

[0027]

[0028] Where, p i The wear coefficient of the brake disc is represented by i = fl, fr, rl, rr, which represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. i This represents the temperature of the brake discs of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e The ambient temperature is represented by D1 and D2, which represent weighting coefficients.

[0029] The four-wheel brake force distribution unit is used to distribute the braking force based on the friction coefficient μ of the brake pads. i And expected total braking force Fb Total Distribute braking force to all four wheels, including:

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

[0031]

[0032] Where m represents the total mass of the electric vehicle, g represents the acceleration due to gravity, and Z represents the acceleration due to gravity. x The values ​​represent the pedal braking intensity of an electric vehicle, where 'a' represents the distance between the front axle and the center of gravity, 'b' represents the distance between the rear axle and the center of gravity, 'L' represents the distance between the front and rear axles, and 'h' represents the distance between the front and rear axles. g Indicates the height of the center of mass;

[0033] Calculate the front-to-rear axle braking force distribution ratio β using the following formula. fr :

[0034]

[0035] Among them, F zfF represents the vertical load on the front axle. zr Z represents the vertical load on the rear axle, a represents the distance between the front axle and the center of gravity, b represents the distance between the rear axle and the center of gravity, and Z represents the vertical load on the rear axle. x h represents the pedal braking intensity of an electric vehicle. g Indicates the height of the center of mass;

[0036] Calculate the target braking torque T for each wheel using the following formula. bdi :

[0037]

[0038] Where, β fr Indicates the front and rear axle braking force distribution ratio, Fb Total R represents the desired total braking force, and μ represents the wheel rolling radius. road T represents the road surface adhesion coefficient. bdfl T bdfr T bdrl T bdrr These represent the target braking torque of the left front wheel, the target braking torque of the right front wheel, the target braking torque of the left rear wheel, and the target braking torque of the right rear wheel, respectively.

[0039] Calculate the target clamping force F of the electromechanical braking system for each wheel before and after using the following formula. cli :

[0040]

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

[0042] The electromechanical braking state division module specifically includes a brake disc contact detection unit and an electromechanical braking system control unit:

[0043] The brake disc contact detection unit is used to detect the ball screw displacement S corresponding to the contact point between the brake and the brake disc. L Displacement S of the ball screws of each wheel brake of the vehicle i i = fl, fr, rl, rr detect the state of the electromechanical braking system and calculate the brake clamping force F. ni :

[0044]

[0045] Where a1, a2, a3, a4, and a5 represent the fitting coefficients, and x iThis represents the lateral displacement after the brake caliper contacts the brake disc, i = fl, fr, rl, rr, when S... i ≤S L At that time, x i =0, when S is satisfied i >S L At that time, x i =S L -S i .

[0046] The electromechanical braking state division module, the electromechanical braking system control unit, is used to determine the minimum clamping force F corresponding to the brake caliper contact point. nmin Brake clamping force F ni Clamping force F with the target cli Determine the mode of the electromechanical braking 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 At this time, the electromechanical braking mode is in the brake gap elimination stage, and 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 At this time, the electromechanical braking mode is in the clamping force following stage, based on the brake clamping force F. ni Clamping force F with the target cli The PID controller is used to follow the clamping force of the target.

[0049] When F is satisfied cli =0 and F ni <F nmin At this time, the electromechanical braking mode is in the brake gap formation stage, and the maximum speed n that the output brake motor can provide is... max And based on the displacement S of the ball screws of the brakes of each wheel of the vehicle i Using a PID controller to control S i Return to the maximum braking gap point.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] 1. A control method for an electromechanical braking system suitable for electric vehicles includes a driving state acquisition module, an electromechanical braking evaluation and calculation module, a braking force calculation and allocation module, and an electromechanical 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 This allows for precise determination of the desired brake clamping force, thereby improving braking accuracy. Attached Figure Description

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

[0054] Figure 1 This is a framework diagram of an electromechanical braking system control method for electric vehicles proposed in this invention. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] like Figure 1 As shown, the present invention is a control method for an electromechanical braking system applicable to electric vehicles, including a driving state acquisition module, an electromechanical braking evaluation and calculation module, a braking force calculation and allocation module, and an electromechanical braking state division module;

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

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

[0059] Calculate the driver's operational awareness evaluation factor K1 using the following formula:

[0060]

[0061] Where α1, α2, α3, α4, and α5 represent weighting coefficients;

[0062] k 11 This represents the driving style coefficient, reflecting the driver's overall tendency in vehicle operation during driving. When the driving style is conservative, k... 11 =0.7, indicating relatively smooth and cautious operation, reducing sudden acceleration and braking. When the driving style is that of a standard driver, k 11 =1.0, the operation is relatively balanced, neither too aggressive nor too conservative. When the driving style is aggressive, k 11 =1.5, aggressive driving, frequent rapid acceleration and braking;

[0063] k 12 k represents the driving mode coefficient, reflecting the vehicle driving mode selected by the driver. When the mode is economy mode, k 12 =0.5, the driver's operation is relatively smooth and energy-efficient, and the driver's awareness of operation is strong. When the mode is standard mode, k 12 =1.0, the driver's operation is relatively balanced, adapting to various driving environments. When the mode is Sport mode, k 12 =1.5, the driver tends to accelerate and brake aggressively, and may have low operational awareness;

[0064] k 13 k represents the environmental complexity coefficient, reflecting the complexity of the environment in which the driver is driving. When in a simple environment, k... 13 =0.2, smooth traffic, good weather, simple road conditions, when in a moderate environment, k 13 =0.5, traffic is relatively congested or the weather is unstable, the driving environment is complex, and when in a complex environment, k 13 =1.0, heavy traffic, congested roads, and inclement weather greatly increase the stress on drivers;

[0065] k 14 k represents the risk perception coefficient, reflecting the driver's sensitivity to potential risks. When the risk perception is low, k... 14 =0.2, the driver pays less attention to surrounding risks and may ignore potential dangers. When the driver is in a state of moderate risk perception, k 14 =0.5, the driver is able to identify and deal with certain risks, high risk perception, k 14 =1.0, the driver is highly alert and reacts quickly to surrounding risks;

[0066] k 15 k represents the fatigue level coefficient, reflecting the driver's level of physical fatigue. When the driver is in a state of low fatigue, k... 15 =0.2, the driver is energetic and reacts quickly; when under moderate fatigue, k 15=0.5, the driver is somewhat fatigued, and the reaction speed is reduced. When under high fatigue, k 25 =1.0, the driver is very tired, which may affect operational awareness and reaction ability.

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

[0068]

[0069] Where, p i The wear coefficient of the brake disc is represented by i = fl, fr, rl, rr, which represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. V represents the speed of the electric vehicle. xi Representing the longitudinal velocities of each wheel of the vehicle, i = fl, fr, rl, rr, Temp i This represents the temperature of the brake discs of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e The ambient temperature is represented by C1, C2, C3, and C4, which represent weighting coefficients.

[0070] The electromechanical braking evaluation and calculation module establishes a braking deceleration model during vehicle braking, and the pedal braking intensity Z of the electric vehicle is calculated. x Satisfying the formula:

[0071]

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

[0073] The electromechanical braking evaluation and 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 due to gravity, and Z represents the acceleration due to gravity. x K1 represents the average wear factor of the brake disc, K2 represents the driver's operating awareness evaluation factor, and β1 and β2 represent weighting 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 based on the brake friction coefficient p of the brake. ii = fl, fr, rl, rr, the temperature of the brake discs of each wheel of the vehicle (Temp) i i = fl, fr, rl, rr and ambient temperature Temp e Calculate the friction coefficient μ of the brake friction pads i :

[0078]

[0079] Where, p i The wear coefficient of the brake disc is represented by i = fl, fr, rl, rr, which represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. i This represents the temperature of the brake discs of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e The ambient temperature is represented by D1 and D2, which represent weighting coefficients.

[0080] The four-wheel brake force distribution unit is used to distribute the braking force based on the friction coefficient μ of the brake pads. i And expected total braking force Fb Total Distribute braking force to all four wheels, including:

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

[0082]

[0083] Where m represents the total mass of the electric vehicle, g represents the acceleration due to gravity, and Z represents the acceleration due to gravity. x The values ​​represent the pedal braking intensity of an electric vehicle, where 'a' represents the distance between the front axle and the center of gravity, 'b' represents the distance between the rear axle and the center of gravity, 'L' represents the distance between the front and rear axles, and 'h' represents the distance between the front and rear axles. g Indicates the height of the center of mass;

[0084] Calculate the front-to-rear axle braking force distribution ratio β using the following formula. fr :

[0085]

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

[0087] Calculate the target braking torque T for each wheel using the following formula. bdi :

[0088]

[0089] Where, β fr Indicates the front and rear axle braking force distribution ratio, Fb Total R represents the desired total braking force, and μ represents the wheel rolling radius. road T represents the road surface adhesion coefficient. bdfl T bdfr T bdrl T bdrr These represent the target braking torque of the left front wheel, the target braking torque of the right front wheel, the target braking torque of the left rear wheel, and the target braking torque of the right rear wheel, respectively.

[0090] Calculate the target clamping force F of the electromechanical braking system for each wheel before and after using the following formula. cli :

[0091]

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

[0093] The electromechanical braking state division module specifically includes a brake disc contact detection unit and an electromechanical braking system control unit:

[0094] The brake disc contact detection unit is used to detect the ball screw displacement S corresponding to the contact point between the brake and the brake disc. L Displacement S of the ball screws of each wheel brake of the vehicle i i = fl, fr, rl, rr detect the state of the electromechanical braking system and calculate the brake clamping force F. ni :

[0095]

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

[0097] The electromechanical braking state division module, the electromechanical braking system control unit, is used to determine the minimum clamping force F corresponding to the brake caliper contact point. nmin Brake clamping force F ni Clamping force F with the target cli Determine the mode of the electromechanical braking 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 At this time, the electromechanical braking mode is in the brake gap elimination stage, and 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 At this time, the electromechanical braking mode is in the clamping force following stage, based on the brake clamping force F. ni Clamping force F with the target cli The PID controller is used to follow the clamping force of the target.

[0100] When F is satisfied cli =0 and F ni <F nmin At this time, the electromechanical braking mode is in the brake gap formation stage, and the maximum speed n that the output brake motor can provide is... max And based on the displacement S of the ball screws of the brakes of each wheel of the vehicle i Using a PID controller to control S i Return to the maximum braking gap point.

Claims

1. A control method for an electromechanical braking system suitable for electric vehicles, characterized in that, This method Includes the following: The module includes a driving status acquisition module, an electromechanical braking evaluation and calculation module, a braking force calculation and allocation module, and an electromechanical braking status division module. The driving status acquisition module is used to collect basic information during vehicle driving, including the driver's brake pedal opening signal Z. t Brake pedal opening change rate signal Z tv The total mass of the electric vehicle (m), the driving speed of the electric vehicle (V), and the road adhesion coefficient (μ) road The longitudinal speed V of each wheel of the vehicle xi i = fl, fr, rl, rr, representing the brake disc temperatures (Temp) of the left front wheel, right front wheel, left rear wheel, right rear wheel, and each wheel of the vehicle, respectively. i i = fl, fr, rl, rr, ambient temperature Temp e The minimum clamping force F corresponding to the brake caliper contact point nmin The ball screw displacement S corresponding to the contact point between the brake and the brake disc L Displacement S of the ball screws of the brakes of each wheel of the vehicle i i = fl, fr, rl, rr; The electromechanical braking evaluation and calculation module is used to collect various data to calculate the corresponding influencing factors and expected total braking force, including: Calculate the driver's operational awareness evaluation factor K1 using the following formula: ， Where α1, α2, α3, α4, and α5 represent weighting coefficients; k 11 This represents the driving style coefficient, reflecting the driver's overall tendency in vehicle operation during driving. When the driving style is conservative, k... 11 =0.7, indicating relatively smooth and cautious operation, reducing sudden acceleration and braking. When the driving style is that of a standard driver, k 11 =1.0, the operation is relatively balanced, neither too aggressive nor too conservative. When the driving style is aggressive, k 11 =1.5, aggressive operation, frequent rapid acceleration and sudden braking; k 12 k represents the driving mode coefficient, reflecting the vehicle driving mode selected by the driver. When the mode is economy mode, k 12 =0.5, the driver's operation is relatively smooth and energy-efficient, and the driver's awareness is strong. When the mode is standard mode, k 12 =1.0, the driver's operation is relatively balanced, adapting to various driving environments. When the mode is Sport mode, k 12 =1.5, the driver tends to accelerate and brake aggressively, and may have low operational awareness; k 13 k represents the environmental complexity coefficient, reflecting the complexity of the environment in which the driver is driving. When in a simple environment, k... 13 =0.2, smooth traffic, good weather, simple road conditions, when in a medium environment, k 13 =0.5, traffic is relatively congested or the weather is unstable, the driving environment is complex, and when in a complex environment, k 13 =1.0, heavy traffic, congested roads, and inclement weather greatly increase the stress on drivers; k 14 k represents the risk perception coefficient, reflecting the driver's sensitivity to potential risks. When the risk perception is low, k... 14 =0.2, the driver pays less attention to surrounding risks and may ignore potential dangers. When the risk perception is moderate, k 14 =0.5, the driver is able to identify and deal with certain risks, high risk perception, k 14 =1.0, the driver is highly alert and reacts quickly to surrounding risks; k 15 k represents the fatigue level coefficient, reflecting the driver's level of physical fatigue. When the driver is in a state of low fatigue, k... 15 =0.2, the driver is energetic and reacts quickly; when under moderate fatigue, k 15 =0.5, the driver is somewhat fatigued and his reaction speed has decreased. When under high fatigue, k 25 =1.0, the driver is very fatigued, which may affect operational awareness and reaction ability.

2. The electromechanical braking system control method for electric vehicles according to claim 1, characterized in that, The electromechanical braking evaluation and calculation module calculates the average wear factor K2 of the brake disc according to the following formula: ， ， Where, p i The wear coefficient of the brake disc is represented by i = fl, fr, rl, rr, which represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. V represents the speed of the electric vehicle. xi Representing the longitudinal velocities of each wheel of the vehicle, i = fl, fr, rl, rr, Temp i This represents the temperature of the brake discs of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e The ambient temperature is represented by C1, C2, C3, and C4, which represent weighting coefficients.

3. The electromechanical braking system control method for electric vehicles according to claim 2, characterized in that, The electromechanical braking evaluation and calculation module establishes a braking deceleration model during vehicle braking, and the pedal braking intensity Z of the electric vehicle is calculated. x Satisfying the formula: ， Among them, Z t Z represents the brake pedal opening signal. tv This represents the rate of change of brake pedal opening, and w1, w2, w3, w4, and w5 represent weighting coefficients.

4. The electromechanical braking system control method for electric vehicles according to claim 3, characterized in that, The electromechanical braking evaluation and 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 due to gravity, and Z represents the acceleration due to gravity. x K1 represents the driver's operational awareness evaluation factor, K2 represents the brake disc average wear factor, and β1 and β2 represent weighting coefficients.

5. A control method for an electromechanical braking system suitable for electric vehicles according to claim 4, 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 based on the brake friction coefficient p of the brake. i i = fl, fr, rl, rr, the temperature of the brake discs of each wheel of the vehicle (Temp) i i = fl, fr, rl, rr and ambient temperature Temp e Calculate the friction coefficient μ of the brake friction pads i : ， Where, p i The wear coefficient of the brake disc is represented by i = fl, fr, rl, rr, which represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. i This represents the temperature of the brake discs of each wheel of the vehicle, i = fl, fr, rl, rr, Temp e The ambient temperature is represented by D1 and D2, which represent weighting coefficients. The four-wheel brake force distribution unit is used to distribute the braking force based on the friction coefficient μ of the brake pads. i And expected total braking force Fb Total Distribute braking force to all four wheels, including: Calculate the vertical load F on the front axle during braking using the following formula. zf Vertical load F of the rear axle zr : ， Where m represents the total mass of the electric vehicle, g represents the acceleration due to gravity, and Z represents the acceleration due to gravity. x The values ​​represent the pedal braking intensity of an electric vehicle, where 'a' represents the distance between the front axle and the center of gravity, 'b' represents the distance between the rear axle and the center of gravity, 'L' represents the distance between the front and rear axles, and 'h' represents the distance between the front and rear axles. g Indicates the height of the center of mass; Calculate the front-to-rear axle braking force distribution ratio β using the following formula. fr : ， Among them, F zf F represents the vertical load on the front axle. zr Z represents the vertical load on the rear axle, a represents the distance between the front axle and the center of gravity, b represents the distance between the rear axle and the center of gravity, and Z represents the vertical load on the rear axle. x h represents the pedal braking intensity of an electric vehicle. g Indicates the height of the center of mass; Calculate the target braking torque T for each wheel using the following formula. bdi : ， Where, β fr Indicates the front and rear axle braking force distribution ratio, Fb Total R represents the desired total braking force, and μ represents the wheel rolling radius. road T represents the road surface adhesion coefficient. bdfl T bdfr T bdrl T bdrr These represent the target braking torque of the left front wheel, the target braking torque of the right front wheel, the target braking torque of the left rear wheel, and the target braking torque of the right rear wheel, respectively. Calculate the target clamping force F of the electromechanical braking system for each wheel before and after using the following formula. cli : ， Among them, T bdi μ represents the target braking torque. i The friction coefficient of the brake pads is represented by i = fl, fr, rl, rr, R. b Indicates the radius of the brake disc.

6. The electromechanical braking system control method for electric vehicles according to claim 5, characterized in that, The electromechanical braking state division module specifically includes a brake disc contact detection unit and an electromechanical braking system control unit: The brake disc contact detection unit is used to detect the ball screw displacement S corresponding to the contact point between the brake and the brake disc. L Displacement S of the ball screws of the brakes of each wheel of the vehicle i i = fl, fr, rl, rr detect the state of the electromechanical braking system and calculate the brake clamping force F. ni : ， Where a1, a2, a3, a4, and a5 represent the fitting coefficients, and x i This represents the lateral displacement after the brake caliper contacts the brake disc, i = fl, fr, rl, rr, when S... i ≤ S L At that time, x i =0, when S is satisfied i > S L At that time, x i = S L -S i .

7. A control method for an electromechanical braking system suitable for electric vehicles according to claim 6, characterized in that, The electromechanical braking state division module, the electromechanical braking system control unit, is used to determine the minimum clamping force F corresponding to the brake caliper contact point. nmin Brake clamping force F ni Clamping force F with the target cli Determine the mode of the electromechanical braking 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 At this time, the electromechanical braking mode is in the brake gap elimination stage, and the maximum speed n that the output brake motor can provide is... max ; When F is satisfied cli ≥ 0 and F ni > F nmin At this time, the electromechanical braking mode is in the clamping force following stage, based on the brake clamping force F. ni Clamping force F with the target cli The PID controller is used to follow the clamping force of the target. When F is satisfied cli = 0 and F ni < F nmin At this time, the electromechanical braking mode is in the brake gap formation stage, and the maximum speed n that the output brake motor can provide is... max And based on the displacement S of the ball screws of the brakes of each wheel of the vehicle i Using a PID controller to control S i Return to the maximum braking gap point.

Images