WO2022222035A1

WO2022222035A1 - Vehicle braking method and apparatus, and electronic device

Info

Publication number: WO2022222035A1
Application number: PCT/CN2021/088430
Authority: WO
Inventors: 朱飞白; 靳彪; 张永生; 杨维妙
Original assignee: 华为技术有限公司
Priority date: 2021-04-20
Filing date: 2021-04-20
Publication date: 2022-10-27
Also published as: CN113302078A; CN113302078B

Abstract

A vehicle braking method and apparatus (800; 1100), and an electronic device. The method comprises: acquiring a state of charge (SOC) of a traction battery (B1) on a vehicle; if the SOC is greater than a preset SOC threshold value, controlling the vehicle to perform braking; and if the SOC is less than or equal to the SOC threshold value, controlling the vehicle to perform braking and enable braking energy recovery. According to a state of charge (SOC) of a traction battery (B1) on a vehicle, whether to control the vehicle to only perform braking, or to control the vehicle to perform braking and enable braking energy recovery can be determined.

Description

Vehicle braking method, device and electronic device

technical field

The present application relates to the technical field of vehicles, and more particularly, to a vehicle braking method, device and electronic device.

Background technique

With the development of society, vehicles (such as automobiles) have been widely used. With the improvement of human environmental protection concept, new energy vehicles (such as pure electric vehicles or hybrid vehicles) have shown a mainstream development trend. However, due to the limited maximum capacity of power batteries on new energy vehicles, it is difficult to improve the battery life of new energy vehicles. Therefore, how to improve the battery life of new energy vehicles has become a key concern.

During the braking process of new energy vehicles, the drive motor can be used as a motor to generate electricity, that is, the drive motor can convert kinetic energy (that is, braking force) into energy and store it in the power battery on the new energy vehicle, which can effectively improve new energy vehicles. of endurance. Therefore, while controlling the braking of new energy vehicles, turning on braking energy recovery has become one of the key technologies of electric vehicles.

However, there is currently a lack of a solution that can control the new energy vehicle to only brake according to a certain state node of the new energy vehicle, or simultaneously control the new energy vehicle to brake and enable braking energy recovery.

SUMMARY OF THE INVENTION

The present application provides a vehicle braking method, device and electronic device, which can only control the vehicle to brake, or control the vehicle to brake and turn on the vehicle according to the state of charge SOC (state of charge) of the power battery on the vehicle. Braking energy recovery.

In a first aspect, the present application provides a vehicle braking method, including: acquiring a state of charge SOC of a power battery on a vehicle; if the state of charge SOC is greater than a preset state of charge threshold, controlling the vehicle to brake; The electrical state SOC is less than or equal to the state of charge threshold, control the vehicle to brake and turn on the braking energy recovery (the braking energy here is the energy generated by the following motor according to the braking process of the braking system, including the energy generated by the first motor. the first energy and/or the second energy produced by the second motor).

It can be understood that the state of charge SOC of the power battery represents the ratio of the remaining capacity of the power battery to the rated capacity under the same conditions under a constant discharge current, and is usually expressed as a percentage.

In an example, according to the external characteristics of the power battery (such as the internal resistance, open circuit voltage, temperature, current and other parameters of the power battery), the discharge experiment method, the open circuit voltage method, the ampere-hour integration method, the Kalman filter method, the neural The remaining capacity of the power battery is obtained by methods such as the network method. Further, according to the definition of the remaining capacity of the power battery and the state of charge SOC, the state of charge SOC of the power battery is obtained.

Optionally, the state-of-charge threshold may be set according to the rated capacity of the power battery. The state of charge threshold can also be set according to the usage time of the power battery.

When the vehicle needs to be braked, the vehicle braking method provided by the present application determines whether it is necessary to control the vehicle to turn on the braking energy recovery while controlling the vehicle to perform the braking in combination with the obtained state of charge SOC of the power battery, so as to realize the energy control and reuse, and the recovered energy can effectively increase the battery life of vehicles (such as electric vehicles) and achieve energy conservation and emission reduction.

Based on the first aspect, in a possible implementation manner, after acquiring the state of charge SOC of the power battery on the vehicle, the vehicle braking method provided by the present application further includes: acquiring the state information of the motor on the vehicle and the state information of the vehicle .

Further, the state information of the motor includes electrical angular velocity of the motor and/or current information of the motor.

For example, the electrical angular velocity of a motor is obtained from the angular velocity of the motor and the number of pole pairs of the motor. Wherein, the angular velocity of the motor can be collected by a rotation angle sensor arranged on the motor.

For another example, the current information of the motor is obtained by coordinate transformation of the three-phase current of the motor. Among them, the three-phase current of the motor can be collected by the current sensor.

Further, the state information of the vehicle includes the vehicle speed and/or the reference braking deceleration.

For example, the vehicle speed can be collected by a vehicle speed sensor provided on the vehicle.

As another example, the reference brake deceleration is derived based on the brake pedal travel and the vehicle longitudinal dynamics equation. Wherein, the stroke of the brake pedal can be collected by a stroke sensor.

Based on the first aspect, in a possible implementation manner, controlling the vehicle to brake and enabling braking energy recovery includes: inputting the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solving to obtain the motor Based on the voltage information of the motor, determine the torque output by the motor and the energy generated by the motor (that is, the braking energy above); The generated energy is stored in the power battery.

Based on the first aspect, in a possible implementation manner, controlling the vehicle to brake (that is, only controlling the vehicle to brake, and not controlling the vehicle to enable braking energy recovery) includes: combining the state information of the motor with the state information of the vehicle Input the pre-built energy recovery control model, and solve the voltage information of the motor; determine the torque output by the motor based on the voltage information of the motor; based on the torque output by the motor, control the vehicle to brake through the vehicle's braking system.

Based on the first aspect, in a possible implementation manner, after acquiring the state of charge SOC of the power battery on the vehicle, the vehicle braking method provided by the present application further includes constructing an energy recovery control model through the following process: The torque equation, the mechanical equation of the motor, and the state equation of the braking system determine the relationship between the torque of the wheels on the vehicle and the current information of the motor; based on the relationship between the torque of the wheel and the current information of the motor, the longitudinal dynamics equation of the vehicle and the voltage equation of the motor to determine the state equation of the vehicle; based on the state equation of the vehicle and the current information of the motor to determine the actual braking deceleration of the vehicle and the torque of the wheels; based on the actual braking deceleration of the vehicle to determine the first energy recovery control model The objective function is to determine the second objective function and the third objective function of the energy recovery control model based on the torque of the wheels. The distribution ratio of the braking force of the brake and the braking force of the brake of the rear wheel meets the preset distribution ratio as the goal, and the third objective function takes the minimum braking power of the braking system as the goal; based on the first objective function, the second objective function and the third objective function determine the objective function of the energy recovery control model, and determine the constraints of the energy recovery control model.

Based on the first aspect, in a possible implementation manner, the motor includes at least one of a first motor, a second motor, and a third motor; the relationship between the torque of the wheel and the current information of the motor satisfies the following formula:

In the formula, T _hf is the braking torque of the front wheel, T _hr is the braking torque of the rear wheel, T _mf is the feedback torque of the front wheel, T _mr is the feedback torque of the rear wheel, and r ₁ is the braking torque in the braking system. The piston diameter of the master cylinder, _r2 represents the piston diameter of the brake wheel cylinder in the front wheel brake, _r3 represents the piston diameter of the brake wheel cylinder in the rear wheel brake, and _μf represents the front wheel brake in the brake disc. Friction coefficient, μr is the friction coefficient of the brake disc in the brake of the rear wheel, _Re is the _radius of the front/rear wheel, N _P1 is the number of pole pairs of the first motor, N _P2 is the number of pole pairs of the second motor , N _P3 represents the number of magnetic pole pairs of the third motor, ψ _f1 represents the rotor flux linkage of the first motor, ψ _f2 represents the rotor flux linkage of the second motor, ψ _f3 represents the rotor flux linkage of the third motor, and i _q1 represents the first motor flux linkage The quadrature axis current of the motor, i _q2 is the quadrature axis current of the second motor, i _q3 is the quadrature axis current of the third motor, η ₁ is the transmission coefficient between the third motor and the piston push rod of the brake master cylinder, n _f represents the transmission coefficient from the first motor to the front wheels, and n _r represents the transmission coefficient from the second motor to the rear wheels.

Based on the first aspect, in a possible implementation manner, the state equation of the above vehicle is:

In the formula,

represents the first derivative of the direct axis current of the first motor,

represents the first derivative of the quadrature axis current of the first motor,

represents the first derivative of the direct axis current of the second motor,

represents the first derivative of the quadrature axis current of the second motor,

represents the first derivative of the direct axis current of the third motor,

represents the first derivative of the quadrature axis current of the third motor, a represents the braking deceleration of the vehicle,

Represents the first-order differential of the vehicle speed, i _d1 represents the direct-axis current of the first motor, i _q1 represents the quadrature-axis current of the first motor, _id2 represents the direct-axis current of the second motor, and i _q2 represents the quadrature-axis current of the second motor , i _d3 represents the direct-axis current of the third motor, i _q3 represents the quadrature-axis current of the third motor, R _s1 represents the internal resistance of the first motor, R _s2 represents the internal resistance of the second motor, and R _s3 represents the third motor’s internal resistance Internal resistance, L _d1 represents the direct axis inductance of the first motor, L _q1 represents the quadrature axis inductance of the first motor, L _d2 represents the direct axis inductance of the second motor, L _q2 represents the quadrature axis inductance of the second motor, L _d3 represents the The direct-axis inductance of the third motor, L _q3 represents the quadrature-axis inductance of the third motor, ω _r1 represents the electrical angular velocity of the first motor, ω _r2 represents the electrical angular velocity of the second motor, ω _r3 represents the electrical angular velocity of the third motor, u _d1 represents the direct axis voltage of the first motor, u _q1 represents the quadrature axis voltage of the first motor, u _d2 represents the direct axis voltage of the second motor, u _q2 represents the quadrature axis voltage of the second motor, and u _d3 represents the third motor Direct axis voltage, u _q3 represents the quadrature axis voltage of the third motor, ψ _f1 represents the rotor flux linkage of the first motor, ψ _f2 represents the rotor flux linkage of the second motor, ψ _f3 represents the rotor flux linkage of the third motor, T _hf Represents the braking torque of the front wheel, T _hr represents the braking torque of the rear wheel, T _mf represents the feedback torque of the front wheel, T _mr represents the feedback torque of the rear wheel, m _veh represents the mass of the vehicle, and _Re represents the front wheel/rear wheel The radius of the wheel, F _air represents the air resistance of the vehicle, and F _roll represents the rolling resistance of the vehicle.

Based on the first aspect, in a possible implementation manner, the above-mentioned first objective function is:

In the formula, J ₁ represents the function value of the first objective function, a(k+i) represents the actual braking deceleration of the vehicle at the k+ith time, and a _ref (k+i) represents the vehicle at the k+ith time The reference braking deceleration, P represents the total number of steps.

a(k+i)-a _ref (k+i) in the first objective function represents the deviation between the actual braking deceleration and the reference braking deceleration at the k+i-th moment of the vehicle (the deviation can be a positive value, can also be negative). Taking the vehicle's ability to track the reference braking deceleration as the goal means that the absolute value of the deviation between the actual braking deceleration and the reference braking deceleration of the vehicle is as small as possible, which can ensure the smoothness of the vehicle's braking and improve the driving experience. .

Based on the first aspect, in another possible implementation manner, the above-mentioned second objective function is:

In the formula, J ₂ represents the function value of the second objective function, T _mf (k+i) represents the feedback torque of the front wheel at the k+i th time, and T _hf (k+i) represents the front wheel at the k+i th time. , T _mr (k+i) represents the feedback torque of the rear wheel at the k+i th time, T _hr (k+i) represents the rear wheel braking torque at the k+i th time, and _Re represents the wheel The radius of , CF represents the preset distribution ratio, and _P represents the total number of steps.

It can be understood that the second objective function takes the actual front and rear wheel braking force distribution ratio to meet the ideal front and rear wheel braking force distribution ratio as the goal, and it is hoped that the actual front and rear wheel braking force distribution ratio The deviation between the ideal front and rear wheel braking force distribution ratio is The smaller the absolute value of , the better, that is, to make the actual front and rear wheel braking force distribution ratio meet the requirements of ECE regulations as much as possible to ensure the safety of vehicle braking.

Based on the first aspect, in yet another possible implementation manner, the above-mentioned third objective function is:

In the formula, J ₃ represents the function value of the third objective function, T _hf (k+i) represents the braking torque of the front wheel at the k+i th time, and T _hr (k+i) represents the rear wheel at the k+i th time. The braking torque at the moment, ω _f (k+i) represents the angular velocity of the front wheel at the k+i th moment, ω _r (k+i) represents the angular velocity of the rear wheel at the k+i th moment, and P _target represents the braking system The target braking power of , P represents the total number of steps.

T _hf (k+i)ω _f (k+i)+T _hr (k+i)ω _r (k+i) in the third objective function above represents the actual braking power of the braking system, T _hf (k +i)ω _f (k+i)+T _hr (k+i)ω _r (k+i)-P _target represents the deviation between the actual braking power and the target braking power (the deviation can be positive, or can be negative). Taking the minimum braking power of the braking system as the goal can indicate that the absolute value of the deviation between the actual braking power and the target braking power is as small as possible, so that the front-drive motor M1 and the rear-drive motor M2 are generated during the regenerative braking process. The energy will be more, and then the maximum energy recovery can be achieved.

Based on the first aspect, in a possible implementation manner, determining the objective function of the energy recovery control model based on the first objective function, the second objective function, and the third objective function includes: assigning the first objective function, the second objective function and the third objective function are weighted, and the objective function of the energy recovery control model is determined with the minimum value of the weighted function as the objective, and the weighting coefficient includes the first weighting coefficient of the first objective function, the second objective The second weighting coefficient of the function and the third weighting coefficient of the third objective function.

The objective function of the above energy recovery control model takes the vehicle's reference braking deceleration and the ideal front and rear wheel braking force distribution ratio as the tracking target, and takes the actual braking power output by the braking system as 0 as the optimization target, which not only improves the braking performance. The smoothness and safety of the movement are realized, and the maximum energy recovery is realized.

Based on the first aspect, in a possible implementation manner, the constraints of the energy recovery control model include voltage constraints and/or voltage increment constraints.

Based on the first aspect, in a possible implementation manner, the above voltage constraints are:

In the formula, u _min1 represents the minimum voltage of the first motor, u _max1 represents the maximum voltage of the first motor, u _min2 represents the minimum voltage of the second motor, u _max3 represents the maximum voltage of the second motor, u _min3 represents The minimum voltage of the third motor, u _max3 represents the maximum voltage of the third motor, u _d1 represents the direct axis voltage of the first motor, u _q1 represents the quadrature axis voltage of the first motor, and u _d2 represents the direct axis voltage of the second motor voltage, u _q2 represents the quadrature axis voltage of the second motor, u _d3 represents the direct axis voltage of the third motor, and u _q3 represents the quadrature axis voltage of the third motor;

The voltage increment constraint is:

In the formula, ‖Δu _d1 ‖ represents the direct-axis voltage increment of the first motor, ‖Δu _q1 ‖ represents the quadrature-axis voltage increment of the first motor, ‖Δu _d1max ‖ represents the maximum value of the direct-axis voltage increment of the first motor, ‖Δu _q1max ‖ represents the maximum value of quadrature-axis voltage increment of the first motor, ‖Δu _d2 ‖ represents the direct-axis voltage increment of the second motor, ‖Δu _q2 ‖ represents the quadrature-axis voltage increment of the second motor, ‖Δu _d2max ‖ represents the maximum value of the direct-axis voltage increment of the second motor, ‖Δu _q2max ‖ represents the maximum value of the quadrature-axis voltage increment of the second motor, ‖Δu _d3 ‖ represents the direct-axis voltage increment of the third motor, ‖Δu _q3 ‖ represents the quadrature-axis voltage increment of the third motor, ‖Δu _d3max ‖ represents the maximum value of the direct-axis voltage increment of the third motor, and ‖Δu _q3max ‖ represents the maximum value of the quadrature-axis voltage increment of the third motor.

Based on the determination of the energy recovery control model, the obtained electrical angular velocity of the motor, the current information of the motor, the speed of the vehicle and the reference braking deceleration of the vehicle can be combined to control the vehicle to brake and enable braking energy recovery.

Therefore, based on the first aspect, in a possible implementation manner, determining the torque output by the motor and the energy generated by the motor based on the voltage information of the motor includes: determining the first motor based on the direct-axis voltage and the quadrature-axis voltage of the first motor For the output first torque, the second torque output by the second motor is determined based on the direct axis voltage and the quadrature axis voltage of the second motor, and the third torque output by the third motor is determined based on the direct axis voltage and the quadrature axis voltage of the third motor. ; determining the first energy generated by the first motor based on the first torque output by the first motor, and determining the second energy generated by the second motor based on the second torque output by the second motor.

Based on the first aspect, in a possible implementation manner, based on the torque output by the motor, the vehicle is controlled to brake through the braking system of the vehicle, and the energy generated by the motor is stored in the power battery, including: based on the first motor The output first torque determines the feedback torque of the front wheel, and the feedback torque of the rear wheel is determined based on the second torque output by the second motor; Brake wheel cylinder and rear wheel brake The brake wheel cylinder determines the braking torque of the front wheel and the braking torque of the rear wheel; based on the feedback torque of the front wheel and the braking torque of the front wheel, the front wheel is controlled to perform braking, and The rear wheels are controlled to perform braking based on the feedback torque of the rear wheels and the braking torque of the rear wheels; the first energy generated by the first motor and the second energy generated by the second motor are stored in the power battery.

In the above process of simultaneous braking and energy recovery, the direct-axis voltage and quadrature-axis voltage of the motor output by the energy recovery control model are directly applied to the motor, and then the vehicle braking and braking energy recovery are realized through the motor. Compared with the indirect braking scheme using the lower-level controller (including the braking control unit and the motor control unit), it not only reduces the control link, shortens the braking time of the vehicle, but also reduces the control cost.

Based on the first aspect, in a possible implementation manner, determining the torque output by the motor based on the voltage information of the motor includes: determining the third torque output by the third motor based on the direct axis voltage and the quadrature axis voltage of the third motor.

Based on the first aspect, in a possible implementation manner, based on the torque output by the motor, controlling the vehicle to perform braking through the braking system of the vehicle includes: based on the third torque output by the third motor, using the brake master cylinder, The brake wheel cylinder in the brake of the front wheel and the brake wheel cylinder in the brake of the rear wheel determine the braking torque of the front wheel and the braking torque of the rear wheel; control the front wheel to brake based on the braking torque of the front wheel, and based on the braking torque of the front wheel The braking torque of the rear wheels controls the braking of the rear wheels.

Based on the first aspect, in a possible implementation manner, the above-mentioned vehicle is an electric vehicle.

Based on the first aspect, in a possible implementation manner, the above electric vehicle is an electric vehicle.

In a second aspect, the present application provides a vehicle braking device, including: an acquisition module for acquiring a state of charge SOC of a power battery on a vehicle; a control module for when the state of charge SOC is greater than a preset state of charge When the threshold is reached, the vehicle is controlled to brake; it is also used to control the vehicle to brake and turn on the braking energy recovery when the state of charge SOC is less than or equal to the state of charge threshold (the braking energy here is the motor according to the braking system. The energy generated during the braking process includes the first energy generated by the first motor and/or the second energy generated by the second motor).

The vehicle braking device provided by the second aspect above can determine whether it is necessary to control the vehicle to brake while controlling the vehicle to turn on the braking energy recovery through the state of charge SOC of the power battery, that is, according to the state of charge SOC, the vehicle can only perform braking. The control of braking, or the control of braking the vehicle and turning on the braking energy recovery, realizes the control and reuse of energy, and the recovered energy can effectively increase the battery life of the vehicle and achieve energy saving and emission reduction. In addition, when it is necessary to control the vehicle to brake, it is possible to switch between controlling the vehicle to brake only and to control the vehicle to brake and turn on the braking energy recovery, which can effectively increase the number of vehicles without affecting the braking of the vehicle. of endurance.

Optionally, the vehicle braking device provided in the second aspect above may include a judgment module configured to judge whether the acquired state of charge SOC is greater than a preset state of charge threshold.

Based on the second aspect, in a possible implementation manner, the obtaining module is further configured to: obtain the state information of the motor on the vehicle and the state information of the vehicle; the state information of the motor includes the electrical angular velocity of the motor and/or the current information of the motor; The state information of the vehicle includes the vehicle speed and/or the reference braking deceleration.

It should be noted that the state information of the motor and the state information of the vehicle acquired by the acquisition module are used in the following modeling module to construct an energy recovery control model.

Based on the second aspect, in a possible implementation manner, the control module is used to: input the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solve to obtain the voltage information of the motor; based on the voltage information of the motor Determine the torque output by the motor and the energy generated by the motor; based on the torque output by the motor, control the vehicle to brake through the vehicle's braking system, and store the energy generated by the motor (ie, braking energy) into the power battery.

Based on the second aspect, in a possible implementation manner, the control module is used to: input the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solve to obtain the voltage information of the motor; based on the voltage information of the motor Determine the torque output by the motor; based on the torque output by the motor, control the vehicle to brake through the braking system of the vehicle.

Based on the second aspect, in a possible implementation manner, the vehicle braking device provided by the present application further includes a modeling module, where the modeling module is used for: based on the electromagnetic torque equation of the motor, the mechanical equation of the motor, and the braking system The state equation determines the relationship between the torque of the wheel on the vehicle and the current information of the motor; the state equation of the vehicle is determined based on the relationship between the torque of the wheel and the current information of the motor, the longitudinal dynamics equation of the vehicle and the voltage equation of the motor; The state equation of the vehicle and the current information of the motor determine the actual braking deceleration of the vehicle and the torque of the wheels; determine the first objective function of the energy recovery control model based on the actual braking deceleration of the vehicle, and determine the energy recovery control based on the torque of the wheels The second objective function and the third objective function of the model, the first objective function takes the vehicle to be able to track the reference braking deceleration as the target, and the second objective function takes the braking force of the front wheel brake and the braking force of the rear wheel brake on the vehicle. The distribution ratio of the system satisfies the preset distribution ratio as the goal, and the third objective function takes the minimum braking power of the braking system as the goal; based on the first objective function, the second objective function and the third objective function Determine the objective of the energy recovery control model function, and determine the constraints of the energy recovery control model.

The motor includes at least one of a first motor, a second motor, and a third motor.

The relationship between the torque of the wheel and the current information of the motor satisfies the following formula:

The state equation of the vehicle is:

In the formula,

represents the first derivative of the direct axis current of the first motor,

represents the first derivative of the direct axis current of the second motor,

represents the first derivative of the direct axis current of the third motor,

The first objective function above is:

The first objective function is based on the vehicle's ability to track the reference braking deceleration, which can ensure the smoothness of the vehicle's braking and improve the driving experience.

The second objective function above is:

The second objective function takes the actual front and rear wheel braking force distribution ratio to meet the ideal front and rear wheel braking force distribution ratio as the goal, indicating that the absolute value of the deviation between the actual front and rear wheel braking force distribution ratio and the ideal front and rear wheel braking force distribution ratio is smaller. The better, that is, to make the actual front and rear wheel braking force distribution ratio meet the requirements of ECE regulations as much as possible to ensure the safety of vehicle braking.

The third objective function above is:

In the formula, J ₃ represents the function value of the third objective function, T _hf (k+i) represents the braking torque of the front wheel at the k+ith moment, and _{Th hr} (k+i) represents the rear wheel at the k+ith time. The braking torque at the moment, ω _f (k+i) represents the angular velocity of the front wheel at the k+i th moment, ω _r (k+i) represents the angular velocity of the rear wheel at the k+i th moment, and P _target represents the braking system The target braking power of , P represents the total number of steps.

The third objective function takes the minimum braking power of the braking system as the goal, which can indicate that the absolute value of the deviation between the actual braking power and the target braking power is as small as possible, so that the front-drive motor M1 and the rear-drive motor M2 are in the regenerative braking The more energy is generated in the process, the maximum energy recovery can be achieved.

The constraints of the above energy recovery control model include voltage constraints and/or voltage increment constraints.

The above voltage constraints are:

The above voltage increment constraints are:

Based on the second aspect, in a possible implementation manner, the above-mentioned modeling module is used to: weight the first objective function, the second objective function and the third objective function based on a preset weighting coefficient, and use the weighted The minimum function value is the target, and the objective function of the energy recovery control model is determined. The weighting coefficient includes the first weighting coefficient of the first objective function, the second weighting coefficient of the second objective function and the third weighting coefficient of the third objective function.

The modeling module takes the vehicle's reference braking deceleration and the ideal front and rear wheel braking force distribution ratio as the tracking target, and takes the actual braking power output by the braking system as 0 as the optimization target, which not only improves the braking smoothness and stability. Safety and maximum energy recovery. In a possible implementation manner, the above-mentioned control module is used to: determine the first torque output by the first motor based on the direct-axis voltage and the quadrature-axis voltage of the first motor, and determine the first torque output by the first motor based on the direct-axis voltage and the quadrature-axis voltage of the second motor. the second torque output by the second motor, and the third torque output by the third motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the third motor; the first energy generated by the first motor is determined based on the first torque output by the first motor , and the second energy generated by the second motor is determined based on the second torque output by the second motor.

Based on the second aspect, in a possible implementation manner, the control module is configured to: determine the feedback torque of the front wheels based on the first torque output by the first motor, and determine the feedback torque of the rear wheels based on the second torque output by the second motor Torque; based on the third torque output by the third motor, the braking torque of the front wheel and the braking of the rear wheel are determined by the brake master cylinder, the brake wheel cylinder of the front wheel brake and the brake wheel cylinder of the rear wheel brake torque; control the front wheel to brake based on the feedback torque of the front wheel and the braking torque of the front wheel, and control the rear wheel to brake based on the feedback torque of the rear wheel and the braking torque of the rear wheel; An energy and a second energy generated by the second motor are stored in the power battery.

Based on the second aspect, in a possible implementation manner, the above-mentioned control module is configured to: determine the third torque output by the third motor based on the direct-axis voltage and the quadrature-axis voltage of the third motor.

Based on the second aspect, in a possible implementation manner, the above-mentioned control module is used to: based on the third torque output by the third motor, through the brake master cylinder, the brake of the front wheel, the brake wheel cylinder and the rear wheel The brake wheel cylinder in the brake determines the braking torque of the front wheel and the braking torque of the rear wheel; controls the front wheel to brake based on the braking torque of the front wheel, and controls the rear wheel to brake based on the braking torque of the rear wheel.

Based on the second aspect, in a possible implementation manner, the above-mentioned vehicle is an electric vehicle.

Based on the second aspect, in a possible implementation manner, the above-mentioned electric vehicle is an electric vehicle.

In a third aspect, the present application provides a vehicle braking device, comprising: an acquisition module for acquiring a state of charge SOC of a power battery on a vehicle; a braking system for when the state of charge SOC is greater than a preset charge When the state of charge SOC is less than or equal to the state of charge threshold, braking is performed; and when the state of charge SOC is less than or equal to the state of charge threshold, the vehicle is controlled to brake and the braking energy recovery is turned on.

Based on the third aspect, in a possible implementation manner, the vehicle braking device provided by the third aspect of the present application further includes an energy recovery controller, where the energy recovery controller is coupled to the acquisition module and the braking system ;

The acquisition module is further configured to: acquire the state information of the motor on the vehicle and the state information of the vehicle;

The energy recovery controller is used for: determining the voltage of the motor according to the state information of the motor and the state information of the vehicle.

The braking system is further used for: controlling the vehicle to perform braking according to the voltage of the motor, or controlling the vehicle to perform braking and enabling braking energy recovery.

The vehicle braking device provided by the third aspect inputs the state information of the motor on the vehicle and the state information of the vehicle obtained by the acquisition module into the energy recovery controller, and outputs the voltage of the motor through the energy recovery controller, and the braking system Control the vehicle to brake, or control the vehicle to brake and turn on the braking energy recovery. Compared with the scheme using the indirect braking of the lower controller, it not only reduces the control link, shortens the braking time of the vehicle, but also reduces the control cost.

Based on the third aspect, in a possible implementation manner, the acquisition module may include at least one sensor. In this embodiment of the present application, a plurality of sensors may be provided.

For example, the acquisition module can set the current sensor. The current sensor is used to collect the three-phase currents of the front-drive motor M1, the rear-drive motor M2 and the booster motor M3 (the three-phase current is subjected to coordinate transformation (such as Parker transformation), and the respective direct-axis current and quadrature-axis current of the three motors can be obtained. ). It should be noted that the three-phase currents of the three motors can be collected through one current sensor, and the three-phase currents of the three motors can also be collected through three sensors respectively.

For another example, the collection module may be provided with a vehicle speed sensor. The vehicle speed sensor is used to collect the vehicle speed.

For another example, the collection module may be provided with a travel sensor. The travel sensor is used to collect the brake pedal travel (the reference braking deceleration of the vehicle can be obtained through the brake pedal travel and the longitudinal dynamics equation of the vehicle).

In a fourth aspect, the present application provides an electronic device, comprising: at least one processor; a memory for storing one or more programs; when the one or more programs are executed by at least one processor, the first Aspects and methods in their possible implementations.

In a fifth aspect, the present application provides a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and when the instructions are run on a computer, are used to execute the aforementioned first aspect and possible implementations thereof. method.

In a sixth aspect, the present application provides a computer program product, the computer program product contains instructions, and when the instructions are run on a computer or a processor, the computer or processor can be implemented as described in the first aspect and possible implementations thereof. Methods.

It should be understood that the second to sixth aspects of the present application are consistent with the technical solutions of the first aspect of the present application, and the beneficial effects obtained by each aspect and the corresponding feasible implementation manner are similar, and will not be repeated.

Description of drawings

1 is a schematic structural diagram of an electric vehicle provided by an embodiment of the present application;

2 is a schematic flowchart of a vehicle braking method provided by an embodiment of the present application;

3 is a schematic flowchart of a vehicle braking method provided by an embodiment of the present application;

FIG. 4 is a schematic flowchart of controlling an electric vehicle to brake and turn on braking energy recovery in an embodiment of the application;

5 is a schematic flowchart of controlling an electric vehicle to brake in an embodiment of the application;

6 is another schematic flowchart of a vehicle braking method provided by an embodiment of the present application;

FIG. 7 is a schematic flowchart of constructing an energy recovery control model in an embodiment of the application;

FIG. 8 is a schematic structural diagram of a vehicle braking device provided by an embodiment of the present application;

9 is a schematic structural diagram of a vehicle braking device provided by an embodiment of the present application;

10 is a schematic structural diagram of a vehicle braking device provided by an embodiment of the application;

11 is a schematic structural diagram of a vehicle braking device provided by an embodiment of the application;

FIG. 12 is a schematic structural diagram of a vehicle braking device provided by an embodiment of the application.

Detailed ways

The technical solutions in the present application will be described below with reference to the accompanying drawings.

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the accompanying drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application. , not all examples. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

The terms "first", "second", etc. in the description, embodiments and claims of the present application and the drawings are only used for the purpose of distinguishing and describing, and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implied order. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, eg, comprising a series of steps or elements. A method, system, product or device is not necessarily limited to those steps or units expressly listed, but may include other steps or units not expressly listed or inherent to the process, method, product or device.

It should be understood that, in this application, "at least one (item)" refers to one or more, and "a plurality" refers to two or more. "And/or" is used to describe the relationship between related objects, indicating that there can be three kinds of relationships, for example, "A and/or B" can mean: only A, only B, and both A and B exist , where A and B can be singular or plural. The character "/" generally indicates that the associated objects are an "or" relationship. "At least one item(s) below" or similar expressions thereof refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (a) of a, b or c, can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and" , where a, b, c can be single or multiple.

The automotive industry is prospering with the ever-increasing demand for vehicles such as automobiles in society. Especially new energy vehicles (such as pure electric vehicles or hybrid vehicles) have been widely used. When the new energy vehicle is braking, the drive motor used to drive the wheels to rotate can also act as a generator to generate electricity while generating feedback torque (the feedback torque acts on the wheels to brake the vehicle). The generated energy is stored in the power battery, which can effectively improve the battery life of new energy vehicles, and can achieve energy saving and emission reduction. Therefore, in the process of controlling the vehicle to brake, simultaneously controlling the vehicle to turn on the braking energy recovery has become one of the key technologies of the new energy vehicle.

In order to control the vehicle to brake and enable the braking energy recovery, the embodiment of the present application first obtains the braking torque of the braking system and the feedback torque of the driving motor in the new energy vehicle by optimizing the energy recovery controller; The brake control unit of the braking system executes the braking torque of the braking system (that is, the braking control unit controls the braking system to execute the braking torque), and also executes the feedback of the drive motor through the motor control unit for controlling the drive motor Torque (that is, the motor control unit controls the drive motor to perform feedback torque). It should be noted that the drive motor will generate energy while executing the feedback torque. Through the above process, the braking force generated by the braking torque and the feedback force generated by the feedback torque can be coordinated and distributed to the wheels, so as to ensure the smoothness of the vehicle braking. More importantly, energy recovery can be achieved during the braking process of the vehicle.

It should be noted that the above-mentioned braking control unit and motor control unit are both execution units, and the braking torque executed by the braking control unit and the feedback torque executed by the motor control unit are both obtained through the energy recovery controller, so this application Embodiments may define an energy recovery controller as an upper-level controller, and may also define a brake control unit and a motor control unit as a lower-level controller.

However, because the lower-level controller cannot ideally track the braking torque of the braking system and the feedback torque of the drive motor, the braking effect and energy recovery effect of the vehicle are both poor. Moreover, the above-mentioned braking and energy recovery require an upper-level controller and a lower-level controller during the execution process, so the cost will be relatively high.

Then, in order to solve the above technical problem, the embodiments of the present application provide a vehicle braking method. The vehicle braking method provided in the embodiments of the present application can be applied to new energy vehicles such as electric vehicles (that is, pure electric vehicles) or hybrid vehicles, and of course, can also be applied to internal combustion engine vehicles such as gasoline engine vehicles, which are not specifically limited in the embodiments of the present application .

Exemplarily, electric vehicles can be classified into front-drive electric vehicles, rear-drive electric vehicles, and distributed-drive electric vehicles according to different driving modes. Among them, the front-drive electric vehicle drives the front wheel to rotate through the front-drive motor (that is, the driving motor that drives the rotation of the front wheel), and realizes the braking through the braking system. The rear-drive electric vehicle drives the rear wheel to rotate through the rear-drive drive motor (the drive motor that drives the rear wheel to rotate), and realizes braking through the braking system. It should be noted that the distributed drive electric vehicle is driven by the front-drive motor and the rear-drive motor together. Since this type of electric vehicle includes a front-drive motor and a rear-drive motor, it is called a distributed drive electric vehicle. The embodiments of the present application take a distributed drive electric vehicle (hereinafter referred to as an electric vehicle for short) as an example to illustrate the braking method of an electric vehicle.

FIG. 1 is a schematic structural diagram of an electric vehicle according to an embodiment of the present application. As shown in FIG. 1 , the structure 100 includes a wheel (including a front wheel (ie, the front wheel W(wheel) 1 and the front wheel W(wheel) 2 in FIG. 1 ) and a rear wheel (ie, the rear wheel W(wheel) in FIG. 1 ) )3 and rear wheel W(wheel)4)), motor (including drive motor (including front drive motor M(motor)1 and rear drive motor M(motor)2) and booster motor M(motor)3), power battery B (batter) 1, electronic control unit ECU (electronic control unit, also known as energy recovery controller) and braking system B (brake) 2. Wherein, the braking system B2 may adopt a mechanical linear braking system, a hydraulic linear braking system, a pneumatic linear braking system or an electromagnetic braking-by-wire system, and the embodiment of the present application adopts a hydraulic linear braking system to realize electric vehicle brake.

Further, referring to FIG. 1 , the front drive motor M1 is connected to the two front wheels (front wheel W1 and the front wheel W2) through the transmission mechanism G(gear) 1, and the rear drive motor M2 is connected to the two rear wheels through the transmission mechanism G(gear) 2. The wheels (rear wheel W3 and rear wheel W4) are connected, and the booster motor M3 is coupled to the braking system B2 through the transmission mechanism G(gear) 3, and the braking system B2 is connected to the four wheels. The braking system B2 has a brake caliper C (caliper) 1 arranged near the front wheel W1, a brake caliper C (caliper) 2 arranged near the front wheel W2, and a brake caliper C (caliper) 2 arranged near the rear wheel W3. ) 3 and the brake caliper C (caliper) 4 arranged near the rear wheel W4 are coupled to control the actions of the brake caliper C1 , the brake caliper C2 , the brake caliper C3 and the brake caliper C4 . At the same time, the ECU is electrically connected to the front-drive motor M1, the rear-drive motor M2 and the booster motor M3, and is used to send the obtained direct-axis voltage of the front-drive motor M1 and the quadrature-axis voltage of the front-drive motor M1 to the front-drive motor M1, and send the obtained rear-drive motor M1. The direct-axis voltage of the drive motor M2 and the quadrature-axis voltage of the rear-drive motor M2 are sent to the rear-drive motor M2, and the obtained direct-axis voltage of the booster motor M3 and the quadrature-axis voltage of the booster motor M3 are also sent to the booster motor M3. The power battery B1 is coupled to the front drive motor M1, the rear drive motor M2, the assist motor M3 and the ECU.

FIG. 2 is a schematic flowchart of a vehicle braking method provided by an embodiment of the present application. As shown in FIG. 2, process 200 may be implemented by the following steps.

Step S201: Obtain the state of charge SOC of the power battery on the electric vehicle.

It is understandable that the power battery set on the electric vehicle, as the energy source of the electric vehicle, determines the battery life of the electric vehicle. Power batteries have a rated capacity in ampere-hours. If the power battery is partially or fully discharged, the remaining capacity of the power battery will be less than the rated capacity of the power battery. The state of charge (SOC) of the power battery represents the ratio of the remaining capacity of the power battery to the rated capacity under the same conditions under a constant discharge current, usually expressed as a percentage. The state of charge SOC can be expressed as:

In the formula, Q _m -Q(I _n ) represents the remaining capacity of the power battery after discharging according to the constant discharge current I _n in the time t; I _n represents the discharge current of the power battery; Q _m represents the power battery according to the discharge current. The maximum discharge capacity when In _is discharging, that _is , the rated capacity of the power battery; Q(In) represents the capacity released by the power battery when the power battery is discharged at a constant discharge current In during time _t .

Based on the above definition of the state of charge SOC, it can be understood that the value range of the state of charge SOC is 0-1. When the state of charge SOC=0, it means that the power battery is fully discharged, and when the state of charge SOC=0.5, it means that the remaining capacity of the power battery is half of the rated capacity. When the state of charge SOC=1, it means that the power battery is fully charged.

Due to the complexity of the structure of the power battery itself, the state of charge (SOC) of the power battery cannot be obtained by direct measurement, but the power battery can be obtained according to the external characteristics of the power battery (such as the internal resistance, open circuit voltage, temperature, current and other parameters of the power battery) remaining capacity.

In a possible implementation manner, according to the external characteristics of the power battery, in the embodiment of the present application, the discharge experiment method, the open circuit voltage method, the ampere-hour integration method, the Kalman filter method, the neural network method and other methods can be used to obtain the remaining power of the power battery. capacity. After that, the state of charge SOC of the power battery is obtained according to the definitions of the remaining capacity of the power battery and the state of charge SOC.

Step S202: if the obtained state of charge SOC is greater than the preset state of charge threshold, control the vehicle to brake (that is, control the vehicle to only brake without turning on braking energy recovery); if the obtained state of charge SOC is less than or equal to State-of-charge threshold, control the vehicle to brake and turn on braking energy recovery (the braking energy here is the energy generated by the motor according to the braking process of the braking system, including the first energy P M1 generated by the first motor _M1 and /or the second energy P _M2 ) generated by the second motor M2.

Optionally, according to the rated capacity of the power battery, different state-of-charge thresholds can be set. Of course, different state-of-charge thresholds can also be set according to the usage time of the power battery.

Exemplarily, the embodiments of the present application are described by taking the state-of-charge threshold of the power battery as 0.90 as an example.

Further, according to the state of charge SOC obtained in step S201, how to control the electric vehicle to only brake, or control the electric vehicle to brake and turn on braking energy recovery, is described in the following two cases.

Case 1: The obtained state of charge SOC is 0.95. Since 0.95 is greater than 0.90, it can be determined that the remaining capacity of the power battery can provide strong endurance for the electric vehicle (that is, the remaining capacity of the power battery can also support the electric vehicle to drive longer. long mileage). In this case, it is only necessary to control the electric vehicle to brake, and it is not necessary to control the electric vehicle to activate the braking energy recovery.

Case 2: The obtained state of charge SOC is 0.85. Since 0.85 is less than 0.90, it can be determined that the remaining capacity of the power battery cannot provide strong endurance for the electric vehicle (that is, the remaining capacity of the power battery cannot support the electric vehicle for a long mileage). ). In this case, it is necessary to control the electric vehicle to brake and turn on the braking energy recovery.

It should be noted that when the obtained state of charge SOC is 0.90 (that is, the obtained state of charge SOC is equal to the preset state of charge threshold), it is the same as the above case 2, and it is also necessary to control the electric vehicle to brake and turn on the brake. Energy recovery.

It can be understood that if the electric vehicle is controlled to brake and the braking energy recovery is enabled, the recovered energy is used to charge the power battery, so that the SOC of the power battery is greater than 0.90. When the state of charge SOC recovers to above 0.90 (that is, through charging, the state of charge SOC of the power battery is greater than 0.90), when the vehicle needs to be controlled to brake, the electric vehicle can be controlled to perform only braking and control the electric vehicle. Switching between braking and turning on braking energy recovery can effectively increase the battery life of the electric vehicle without affecting the braking of the electric vehicle.

The vehicle braking method provided by the embodiments of the present application determines whether it is necessary to control the vehicle to turn on the braking energy recovery while controlling the vehicle to brake by the state of charge SOC of the power battery. Braking, or controlling the electric vehicle to brake and turning on the braking energy recovery, realizes the control and reuse of energy, and the recovered energy can effectively increase the battery life of the electric vehicle, and realize energy saving and emission reduction.

In a possible implementation manner, after step S201, the vehicle braking method provided by the embodiment of the present application may further acquire the state information of the motor and the state information of the electric vehicle.

For example, the state information of the motors (which may include the front drive motor M1, the rear drive motor M2, and the assist motor M3) may include the electrical angular velocity of the front drive motor M1, the electrical angular velocity of the rear drive motor M2, and the electrical angular velocity of the assist motor M3, and may also include the electrical angular velocity of the front drive motor M1, the electrical angular velocity of the rear drive motor M2, and the electrical angular velocity of the assist motor M3 Current information of the motor M1, current information of the rear drive motor M2, and current information of the assist motor M3.

In an example, the electrical angular velocity (represented by ω _r1 ) of the front drive motor M1 is obtained by combining the angular velocity (represented by ω ₁ ) of the front drive motor M1 collected by the rotation angle sensor (set on the front drive motor M1 ) with the magnetic pole of the front drive motor M1 It is obtained by multiplying the logarithms (represented by N _P1 ), and is expressed by the formula as ω _r1 =ω ₁ ×N _P1 .

In another example, the electrical angular velocity (represented by ω _r2 ) of the rear drive motor M2 is obtained by combining the angular velocity (represented by ω ₂ ) of the rear drive motor M2 collected by the rotation angle sensor (disposed on the rear drive motor M2 ) with the rear drive motor M2 It is obtained by multiplying the number of pole pairs (represented by N _P2 ) of the driving motor M2 , and is represented by a formula as ω _r2 =ω ₂ ×N _P2 .

In yet another example, the electrical angular velocity (represented by ω _r3 ) of the assist motor M3 is obtained by combining the angular velocity (represented by ω ₃ ) of the assist motor M3 collected by the rotational angle sensor (disposed on the assist motor M3 ) with the angular velocity of the assist motor M3 The number of magnetic pole pairs (represented by N _P3 ) is multiplied, and it is expressed by the formula as ω _r3 =ω ₃ ×N _P3 .

It should also be noted that the current information of the front drive motor M1 may be obtained by performing coordinate transformation (such as Parker transformation) on the three-phase current of the front drive motor M1 collected by the current sensor, and the current information of the rear drive motor M2 may be obtained by converting the current sensor The collected three-phase current of the rear drive motor M2 is obtained by performing coordinate transformation (such as Parker transformation), and the current information of the booster motor M3 can be obtained by performing coordinate transformation (eg, Parker transformation) on the three-phase current of the booster motor M3 collected by the current sensor. )owned.

For another example, the state information of the electric vehicle may include the vehicle speed of the electric vehicle, and may also include the reference braking deceleration of the electric vehicle.

It should be noted that the vehicle speed of the electric vehicle can be acquired by a vehicle speed sensor provided on the electric vehicle.

It should also be noted that the reference braking deceleration of the electric vehicle may be based on the brake pedal stroke collected by the stroke sensor, and obtained through the longitudinal dynamic equation of the electric vehicle (for the expression, please refer to the introduction below).

In another possible implementation manner, in order to control the electric vehicle to only brake, or to control the electric vehicle to brake and turn on the braking energy recovery, after step S201, the vehicle braking method provided in this embodiment of the present application may also Build an energy recovery control model.

Further, the energy recovery control model may include objective functions and constraints. The objective function may include a first objective function, a second objective function, and a third objective function, and the constraints may include voltage constraints and/or voltage increment constraints. The embodiments of the present application take voltage constraints and voltage increment constraints as examples. Explain the constraints.

In a possible implementation manner, the front drive motor M1, the rear drive motor M2 and the booster motor M3 all use permanent magnet synchronous motors, so the voltage equation, electromagnetic torque equation and mechanical The equations are the same. In the embodiment of the present application, the front-drive motor M1 is taken as an example, and an energy recovery control model is constructed through the following steps S201a' to S201e'.

Step S201a': Determine the relationship between the torque of the wheel and the current information of the front-wheel motor M1 based on the electromagnetic torque equation of the front-wheel motor M1, the mechanical equation of the front-wheel motor M1, and the state equation of the braking system.

In a possible implementation, the electromagnetic torque equation of the front-drive motor M1 can be expressed as:

In the formula, T _e1 represents the electromagnetic torque of the front-drive motor M1, the unit is Nm; N _P1 represents the number of magnetic pole pairs of the front-wheel motor M1; ψ _f1 represents the rotor flux linkage of the front-wheel motor M1, the unit is Vs/rad; i _d1 represents the front-wheel motor M1 The direct-axis current of the motor is A, the unit is A; i _q1 is the quadrature-axis current of the front-drive motor M1, the unit is A; L _d1 is the direct-axis inductance of the motor, the unit is H; L _q is the quadrature-axis inductance of the motor, the unit is H.

Further, when L _d1 =L _q1 , the electromagnetic torque equation of the front-drive motor M1 can also be expressed as:

In another possible implementation manner, the mechanical equations of the front-drive motor M1 may be introduced in the two cases of the front-drive motor M1 as a motor and a generator.

When the front drive motor M1 is used as a motor, the mechanical equation of the front drive motor M1 can be expressed as:

In the formula, J ₁ represents the moment of inertia of the front drive motor M1, the unit is kg m^2, B ₁ represents the damping coefficient of the driving motor M1, the unit is Nm.s/rad; ω _m1 represents the mechanical speed of the front drive motor M1, the unit is rad/s; T _L1 represents the load torque of the front drive motor M1, in Nm.

When the front drive motor M1 is used as a generator, the mechanical equation of the front drive motor M1 can be expressed as:

It should be noted that, if the influence of J ₁ and B ₁ is ignored, the mechanical equation of the front-drive motor M1 can also be expressed as:

T _L = T _e

In yet another possible implementation, the state equation of the braking system can be expressed as:

In the formula, P _c represents the oil pressure output by the active master cylinder in the braking system, and it satisfies

T _m3 represents the third torque output by the booster motor M3.

Further, by combining the above-mentioned electromagnetic torque equation of the front drive motor M1, the mechanical equation of the front drive motor M1 and the state equation of the braking system, the relationship between the torque of the wheel and the current information of the motor can be obtained.

It should be noted that the moment of the wheel may include the moment of the front wheel and the moment of the rear wheel. The torque of the front wheel may include the braking torque of the front wheel and the feedback torque of the front wheel, and the torque of the rear wheel may include the braking torque of the rear wheel and the feedback torque of the rear wheel.

In an example, for the braking torque of the front wheel, since the braking torque of the front wheel is generated by the booster motor M3, the brake master cylinder of the braking system and the brake wheel cylinder of the front wheel brake, the motor The current information of can include the quadrature axis current of the booster motor M3. Regarding the feedback torque of the front wheel, since the feedback torque of the front wheel is generated by the front drive motor M1, the current information of the motor may include the quadrature axis current of the front drive motor M1.

In another example, for the braking torque of the rear wheel, since the braking torque of the rear wheel is generated by the booster motor M3, the brake master cylinder of the braking system and the brake wheel cylinder of the rear wheel brake, therefore The current information of the motor may include the quadrature axis current of the booster motor M3. Regarding the feedback torque of the rear wheel, since the feedback torque of the rear wheel is generated by the rear drive motor M2, the current information of the motor may include the quadrature axis current of the rear drive motor M2.

According to the above description, the electromagnetic torque equation of the front drive motor M1, the mechanical equation of the front drive motor M1 and the state equation of the braking system can be combined to obtain the relationship between the braking torque of the front wheel and the quadrature axis current of the booster motor M3, the rear The relationship between the braking torque of the wheel and the quadrature axis current of the booster motor M3, the relationship between the feedback torque of the front wheel and the quadrature axis current of the front drive motor M1, and the feedback torque of the rear wheel and the quadrature axis current of the rear drive motor M2 The relationship between.

For example, the relationship between the braking torque of the front wheel and the quadrature axis current of the booster motor M3 can be expressed as:

For another example, the relationship between the braking torque of the rear wheel and the quadrature axis current of the booster motor M3 can be expressed as:

For another example, the relationship between the feedback torque of the front wheel and the quadrature axis current of the front drive motor M1 can be expressed as:

For another example, the relationship between the feedback torque of the rear wheels and the quadrature axis current of the rear drive motor M2 can be expressed as:

In the above four formulas, T _hf is the braking torque of the front wheel, T _hr is the braking torque of the rear wheel, T _mf is the feedback torque of the front wheel, T _mr is the feedback torque of the rear wheel, and r ₁ is the main braking torque. The piston diameter of the cylinder, r ₂ represents the piston diameter of the brake wheel cylinder in the brake of the front wheel, r ₃ represents the piston diameter of the brake wheel cylinder in the brake of the rear wheel, μ _f represents the friction of the brake disc in the brake of the front wheel Coefficient, μ _r represents the friction coefficient of the brake disc in the brake of the rear wheel, _Re represents the radius of the front wheel/rear wheel (in the embodiment of this application, four wheels (including two front wheels and two rear wheels) are used in the electric vehicle. The radius of the wheel) is the same as an example), _NP1 represents the number of magnetic pole pairs of the front drive motor M1, _{NP2 represents the number of magnetic pole pairs of the rear drive motor M2, NP3} _represents the number of magnetic pole pairs of the booster motor M3, ψ _f1 represents the number of magnetic pole pairs of the front drive motor M1 Rotor flux linkage, ψ _f2 denotes the rotor flux linkage of the rear drive motor M2, ψ _f3 denotes the rotor flux linkage of the booster motor M3, i _q1 denotes the quadrature axis current of the front drive motor M1, i _q2 denotes the quadrature axis current of the rear drive motor M2, i _q3 represents the quadrature axis current of the booster motor M3, η ₁ represents the transmission coefficient between the front drive motor M1 and the piston push rod of the brake master cylinder, n _f represents the transmission coefficient from the front drive motor M1 to the front wheel, and n _r represents the rear drive Transmission coefficient of motor M2 to rear wheels.

Step S201b': Determine the state equation of the electric vehicle based on the relationship between the torque of the wheel and the current information of the motor, the longitudinal dynamics equation of the electric vehicle, and the voltage equation of the motor.

In one possible implementation, the longitudinal dynamics equation of an electric vehicle can be formulated as:

In the formula, m _veh represents the mass of the electric vehicle, in kg; a represents the actual braking deceleration of the electric vehicle, in m/s^2; T _hf represents the braking torque of the front wheel, in Nm; T _hr Represents the braking torque of the rear wheel, the unit is Nm; T _mf represents the feedback torque of the front wheel, the unit is Nm; T _mr represents the feedback torque of the rear wheel, the unit is Nm; R _e represents the radius of the wheel, the unit is m; F _air represents the air resistance of the electric vehicle, the unit is N; F _roll represents the rolling resistance of the electric vehicle, the unit is N.

Further, F _air can be expressed as:

In the formula, ρ _air represents the air density in kg/m^3; C _x represents the air coefficient; S represents the windward area of the electric vehicle, in m^2; v represents the speed of the electric vehicle in m/s; v _wind represents the wind speed in m/s.

Further, F _roll can be formulated as:

F _roll = m _veh · g · Sin(arctan(0.01 · α)) ²

In the formula, g is the acceleration of gravity, in m/s^2; α is the road gradient.

In another possible implementation, taking the front drive motor M1 as an example, the voltage equation of the front drive motor M1 can be expressed as:

In the formula, u _d1 represents the direct axis voltage of the front drive motor M1, the unit is V; u _q1 represents the quadrature axis voltage of the front drive motor M1, the unit is V; i _d1 represents the direct axis current of the front drive motor M1, the unit is A; i _q1 Represents the quadrature axis current of the front drive motor M1, the unit is A; R _s1 represents the internal resistance of the front drive motor M1, the unit is Ω; L _d1 represents the direct axis inductance of the front drive motor M1, the unit is H; L _q1 represents the alternating current of the front drive motor M1 Shaft inductance, the unit is H; ω _r1 represents the electrical angular velocity of the front drive motor M1, the unit is rad/s; ψ _f1 represents the rotor flux linkage of the front drive motor M1, the unit is Vs/rad.

In yet another possible implementation, combined with the longitudinal dynamics equation of the electric vehicle and the voltage equation of the motor, the state equation of the electric vehicle can be expressed as:

In the formula, i _d1 represents the direct axis current of the front drive motor M1, i _q1 represents the quadrature axis current of the front drive motor M1, i _d2 represents the direct axis current of the rear drive motor M2, i _q2 represents the quadrature axis current of the rear drive motor M2, i _d3 represents the direct-axis current of the booster motor M3, i _q3 represents the quadrature-axis current of the booster motor M3,

represents the first derivative of the direct-axis current of the front-drive motor M1,

represents the first-order differential of the quadrature-axis current of the front-drive motor M1,

Represents the first-order derivative of the direct-axis current of the rear-drive motor M2,

represents the first-order differential of the quadrature-axis current of the rear-drive motor M2,

Represents the first derivative of the direct-axis current of the booster motor M3,

Represents the first-order differential of the quadrature-axis current of the booster motor M3,

Represents the first-order differential of the vehicle speed, a represents the braking deceleration of the electric vehicle (the unit is m/s^2, the first-order differential of the vehicle speed can be used to obtain the braking deceleration of the electric vehicle), and R _s1 represents the interior of the front-drive motor M1. resistance, R _s2 represents the internal resistance of the rear drive motor M2, R _s3 represents the internal resistance of the booster motor M3, L _d1 represents the direct axis inductance of the front drive motor M1, L _q1 represents the quadrature axis inductance of the front drive motor M1, and L _d2 represents the rear drive motor M1. The direct-axis inductance of the motor M2, L _q2 is the quadrature-axis inductance of the rear drive motor M2, L _d3 is the direct-axis inductance of the booster motor M3, L _q3 is the quadrature-axis inductance of the booster motor M3, and ω _r1 is the electrical angular velocity of the front-drive motor M1 , ω _r2 represents the electrical angular velocity of the rear drive motor M2, ω _r3 represents the electrical angular velocity of the booster motor M3, u _d1 represents the direct axis voltage of the front drive motor M1, u _q1 represents the quadrature axis voltage of the front drive motor M1, u _d2 represents the rear drive motor The direct axis voltage of M2, u _q2 is the quadrature axis voltage of the rear drive motor M2, u _d3 is the direct axis voltage of the booster motor M3, u _q3 is the quadrature axis voltage of the booster motor M3, ψ _f1 is the rotor flux linkage of the front drive motor M1 , ψ _f2 represents the rotor flux linkage of the rear drive motor M2, ψ _f3 represents the rotor flux linkage of the booster motor M3, m _veh represents the mass of the electric vehicle, and _Re represents the radius of the front/rear wheels. _Thf represents the braking torque of the front wheel, T _hr represents the braking torque of the rear wheel, T _mf represents the feedback torque of the front wheel, T _mr represents the feedback torque of the rear wheel; F _air represents the air resistance of the electric vehicle, and F _roll represents the Rolling resistance of the vehicle.

Further, the relationship between T _hf and i _q3 , the relationship between T _hr and i _q3 , the relationship between T _mf and i _q1 , the relationship between T _mr and i _q2 , the expression of F _air , and the F For the expressions of _roll , reference may be made to the foregoing description, and details are not repeated in this embodiment of the present application.

Step S201c': Determine the actual braking deceleration and wheel torque of the electric vehicle based on the state equation of the electric vehicle and the current information of the motor.

Exemplarily, after obtaining the direct-axis current _{id1 of the front-drive motor M1, the quadrature-axis current i q1 of the front-drive motor M1, the direct-axis current id2 of the rear-drive motor M2, the quadrature-axis current i q2} _of _the _rear -drive motor M2, the power assist On the basis of the direct-axis current _{id3 of the motor M3 and the quadrature-axis current i q3} _of the booster motor M3 (that is, the current information of the motor is obtained), _id1 , i _q1 , _id2 , i _q2 , _id3 and i _{q3 are} brought into The equation of state for the above electric vehicle, combined with the relationship between _Thf and i _q3 , the relationship between Th _hr and i _q3 , the relationship between T _mf and i _q1 , the relationship between T _mr and i _q2 , the relationship between T mr and i q2, the The expression of _air and the expression of F _roll can obtain the actual braking deceleration of the electric vehicle and the torque of the wheel (including the braking torque of the front wheel, the braking torque of the rear wheel, the feedback torque of the front wheel and the torque of the rear wheel. feedback torque).

Step S201d': Based on the actual braking deceleration of the electric vehicle and the torque of the wheels, three objective functions (including the first objective function, the second objective function and the third objective function) of the energy recovery control model are determined.

The following describes the determination process of the three objective functions:

1) A first objective function is determined based on the actual braking deceleration of the electric vehicle, taking the trackable reference braking deceleration of the electric vehicle as the target.

Exemplarily, the first objective function can be expressed as:

In the formula, J ₁ represents the function value of the first objective function, a(k+i) represents the actual braking deceleration of the electric vehicle at the k+ith moment, and a _ref (k+i) represents the electric vehicle at the k+th time. The reference braking deceleration at time i, k represents the time, i represents the index of the step, and i=1,2,...,P, P represents the total number of steps.

It should be noted that a(k+i)-a _ref (k+i) in the first objective function represents the deviation between the actual braking deceleration and the reference braking deceleration ( Bias can be positive or negative). Taking the electric vehicle's ability to track the reference braking deceleration as the goal, it means that the absolute value of the deviation between the actual braking deceleration of the electric vehicle and the reference braking deceleration is as small as possible, which can ensure the smoothness of the electric vehicle braking. Improve the driving experience.

2) The distribution ratio of the braking force of the front wheel brake and the braking force of the rear wheel brake on the electric vehicle (that is, the actual front and rear wheel braking force distribution ratio) satisfies the preset distribution ratio (ideal front and rear wheel braking force distribution ratio) ) as the target, and the second objective function is determined based on the torque of the wheel.

In an example, the ideal front-to-rear braking force distribution ratio represents: when the front and rear wheels are locked at the same time, the braking force of the front wheel brake (that is, the brake used to brake the front wheel) in the braking system and the braking system The relationship curve of the braking force of the middle rear wheel brake (ie the brake used to brake the rear wheel). The ideal front and rear brake force distribution ratio can be obtained by the United Nations Economic Commission for Europe (the united nations economic commission for europe, abbreviated UNECE or ECE) regulations.

Further, the second objective function can be expressed as:

In the formula, J ₂ represents the function value of the second objective function, T _mf (k+i) represents the feedback torque of the front wheel at the k+i th time, and T _hf (k+i) represents the front wheel at the k+i th time. , T _mr (k+i) represents the feedback torque of the rear wheel at the k+i th time, T _hr (k+i) represents the rear wheel braking torque at the k+i th time, and _Re represents the wheel The radius of , P represents the total number of steps. _CF represents the preset distribution ratio, _CF can be expressed as:

In the formula, _db represents the distance from the center of mass of the electric vehicle to the rear axle (the rear axle is located between the two rear wheels and is used to connect the two rear wheels), and d _a represents the center of mass of the electric vehicle to the front axle (the front axle is located between the two rear wheels). The distance between the two front wheels is used to connect the two front wheels), z represents the braking strength of the electric vehicle, and h _g represents the height of the center of mass of the electric vehicle.

It should be noted that, according to the relationship between the braking torque and the braking force, (T _mf (k+i)+T _hf (k+i)) _Re in the second objective function represents the braking force of the front wheel brake, the second (T _mr (k+i)+T _hr (k+i)) _Re in the objective function represents the braking force of the rear wheel brake. then,

Indicates the distribution ratio of the braking force of the front wheel brake to the braking force of the rear wheel brake (ie, the actual front and rear wheel braking force distribution ratio). and then,

Indicates the deviation between the actual front and rear wheel braking force distribution ratio and the ideal front and rear wheel braking force distribution ratio (the deviation can be a positive value or a negative value).

In the embodiment of the present application, the absolute value of the deviation between the actual front and rear wheel braking force distribution ratio and the ideal front and rear wheel braking force distribution ratio is expressed as the goal that the actual front and rear wheel braking force distribution ratio satisfies the ideal front and rear wheel braking force distribution ratio The smaller the better, that is, the actual front-to-rear brake force distribution ratio meets the requirements of ECE regulations as much as possible to ensure the safety of electric vehicle braking.

3) The third objective function is determined based on the torque of the wheel with the minimum braking power of the braking system as the goal.

Exemplarily, the third objective function can be expressed as:

It should be noted that T _hf (k+i)ω _f (k+i)+T _hr (k+i)ω _r (k+i) in the third objective function above represents the actual braking power of the braking system , T _hf (k+i)ω _f (k+i)+T _hr (k+i)ω _r (k+i)-P _target represents the deviation between the actual braking power and the target braking power (the deviation can be positive or negative). Taking the minimum braking power of the braking system as the goal can indicate that the absolute value of the deviation between the actual braking power and the target braking power is as small as possible, so that the front-drive motor M1 and the rear-drive motor M2 are generated during the regenerative braking process. The energy will be more, and then the maximum energy recovery can be achieved.

Further, in the embodiment of the present application, the third objective function is described by taking the target braking power of the braking system as 0 (ie, P _target =0) as an example. When P _target =0, the third objective function can be expressed as:

Therefore, aiming at the minimum braking power of the braking system can indicate that the absolute value of the actual braking power is as small as possible, which can also make the front-drive motor M1 and the rear-drive motor M2 generate more power in the process of regenerative braking. energy, so as to achieve maximum energy recovery.

Step S201e': Determine the objective function of the energy recovery control model according to the first objective function, the second objective function and the third objective function, and determine the constraints of the energy recovery control model.

In a possible implementation manner, the weighting coefficients (including the first weighting coefficient (represented by Γ ₁ ) of the first objective function, the second weighting coefficient (represented by Γ ₂ ) of the second objective function, and the third weighting coefficient of the second objective function are set first. _The _third weighting coefficient of the objective function (represented by Γ ₃ ) _; objective function. The objective function of the energy recovery control model can be expressed as:

min J=Γ ₁ ·J ₁ +Γ ₂ ·J ₂ +Γ ₃ ·J ₃

In the formula, J represents the weighted function value, and min J represents the minimum value of J.

In the embodiment of the present application, the reference braking deceleration of the electric vehicle and the ideal front and rear wheel braking force distribution ratio are used as the tracking targets, and the actual braking power output by the braking system is 0 as the optimization target, which not only improves the smoothness of braking Safety and security, and achieve maximum energy recovery.

To obtain min J, the constraints of the energy recovery control model can include voltage constraints and/or voltage increment constraints. The embodiments of the present application describe voltage constraints and voltage increment constraints as constraints.

When determining the constraints, it is necessary to ensure that the direct-axis voltage u _d1 and the quadrature-axis voltage u _q1 of the front-drive motor M1 are smaller than the maximum values u _d1 and u _q1 can reach, and the direct-axis voltage u _d2 and the quadrature-axis voltage u of the rear-drive motor M2 _q2 is smaller than the maximum values that u _d2 and u _q2 can reach, and it is also necessary to ensure that the direct-axis voltage u _d3 and the quadrature-axis voltage u _q3 of the assisting power M3 can be smaller than the maximum values that u _d3 and u _q3 can reach. When the vehicle speed v is lower than the vehicle speed lower limit value v _min (ie v<v _min ), the energy generated by the regenerative braking during the process of generating the feedback torque of the front wheel by the front-wheel drive motor M1 is less than the loss during the charging process of the power battery. In this case, if the electric vehicle performs braking and energy recovery at the same time, the energy recovery needs to be terminated and only braking is performed. The braking force required for braking is provided by the braking system. At this time, the direct axis voltage u _d1 and the quadrature axis voltage u _q1 of the front drive motor M1 can be the minimum values that u _d1 and u _q1 can reach, and the direct axis voltage u d1 of the rear drive motor M2 can be reached. The axial voltage u _d2 and the quadrature axis voltage u _q2 can be the minimum values that u _d2 and u _q2 can achieve, and the direct axis voltage u _d3 and the quadrature axis voltage u _q3 of the assisting power M3 can be the minimum values that u _d3 and u _q3 can achieve minimum value.

Thus, the voltage constraint can be formulated as:

In the formula, u _min1 represents the minimum voltage of the front drive motor M1, u _max1 represents the maximum voltage of the front drive motor M1, u _min2 represents the minimum voltage of the rear drive motor M2, u _max3 represents the maximum voltage of the rear drive motor M2, u _min3 represents the minimum voltage of the booster motor M3, u _max3 represents the maximum voltage of the booster motor M3, u _d1 represents the direct axis voltage of the front drive motor M1, u _q1 represents the quadrature axis voltage of the front drive motor M1, and u _d2 represents the rear drive motor M2 , u _q2 represents the quadrature axis voltage of the rear drive motor M2, u _d3 represents the direct axis voltage of the booster motor M3, and u _q3 represents the quadrature axis voltage of the booster motor M3.

On the basis of the above voltage constraints, the voltage increment constraints also need to be satisfied. The voltage increment constraint can be that the direct-axis voltage increment of the front-drive motor M1 is less than the maximum value that can be achieved by the direct-axis voltage increment of the front-drive motor M1 (that is, the maximum value of the direct-axis voltage increment of the front-drive motor M1), and that of the rear-drive motor M2. The direct-axis voltage increment is smaller than the maximum value of the direct-axis voltage increment of the rear drive motor M2 (that is, the maximum value of the direct-axis voltage increment of the rear-drive motor M2), and the direct-axis voltage increment of the booster motor M3 is smaller than that of the booster motor M3 The maximum value of the direct-axis voltage increment that can be reached (that is, the maximum value of the direct-axis voltage increment of the booster motor M3).

Further, the voltage increment constraint can be formulated as:

In the formula, ‖Δu _d1 ‖ represents the direct-axis voltage increment of the front-wheel motor M1, ‖Δu _q1 ‖ represents the quadrature-axis voltage increment of the front-wheel motor M1, and ‖Δu _d1max ‖ represents the maximum value of the direct-axis voltage increment of the front-wheel motor M1 , ‖Δu _q1max ‖ represents the maximum value of the quadrature-axis voltage increment of the front-drive motor M1, ‖Δu _d2 ‖ represents the direct-axis voltage increment of the rear-drive motor M2, ‖Δu _q2 ‖ represents the quadrature-axis voltage increment of the rear-drive motor M2, ‖Δu _d2max ‖ represents the maximum value of the direct-axis voltage increment of the rear-drive motor M2, ‖Δu _q2max ‖ represents the maximum value of the quadrature-axis voltage increment of the rear-drive motor M2, ‖Δu _d3 ‖ represents the direct-axis voltage of the booster motor M3 Increment, ‖Δu _q3 ‖ represents the quadrature-axis voltage increment of the booster motor M3, ‖Δu _d3max ‖ represents the maximum value of the direct-axis voltage increment of the booster motor M3, ‖Δu _q3max ‖ represents the maximum quadrature-axis voltage increment of the booster motor M3 value.

It should be noted that, in this embodiment of the present application, the electrical angular velocity ω _r1 of the front-drive motor M1, the electrical angular velocity ω _r2 of the rear-drive motor M2, the electrical angular velocity ω _r3 of the assist motor M3, and the i of the front-drive motor M1 are input into the energy recovery control model. _d1 and i _q1 , i _d2 and i _q2 of the rear drive motor M2 , i _d3 and i _q3 of the booster motor M3 , the vehicle speed v of the electric vehicle and the reference braking deceleration a _ref as state variables, will be output from the energy recovery control model The direct axis voltage u _d1 and quadrature axis voltage u _q1 of the front drive motor M1, the direct axis voltage u _d2 and quadrature axis voltage u _q2 of the rear drive motor M2, and the direct axis voltage u _d3 and quadrature axis voltage u _q3 of the booster motor M3 are taken as The control variables are based on the actual braking deceleration of the electric vehicle, the actual front and rear wheel braking force distribution ratio and the actual braking power of the braking system (with the reference braking deceleration of the electric vehicle and the ideal front and rear wheel braking force distribution). ratio as the tracking target, and taking the actual braking power output by the braking system as 0 as the optimization target), an energy recovery control model is constructed.

Based on the determination of the energy recovery control model, the obtained electrical angular velocity of the front drive motor M1, the electrical angular velocity of the rear drive motor M2, the electrical angular velocity of the assist motor M3, the current information of the front drive motor M1, and the current of the rear drive motor M2 can be combined. information, the current information of the booster motor M3, the vehicle speed of the electric vehicle, and the reference braking deceleration of the electric vehicle, so as to control the electric vehicle to brake and turn on the braking energy recovery.

FIG. 3 shows a schematic flowchart of a vehicle braking method provided by an embodiment of the present application. The following steps S202a1 to 202a3 and steps 202b1 to 202b3 can all be implemented with reference to FIG. 3 .

In an example, the process 400 (as shown in FIG. 4 ) of controlling the electric vehicle to brake and turn on the braking energy recovery can be implemented through the following steps S202a1 to S202a3.

Step S202a1: Referring to FIG. 3 and FIG. 4, compare the electrical angular velocity ω _r1 of the front drive motor M1, the electrical angular velocity ω _r2 of the rear drive motor M2, the electrical angular velocity ω _r3 of the assist motor M3, and the current information of the front drive motor M1 (including _id1 and i _q1 ), the current information of the rear drive motor M2 (including _id2 and i _q2 ), the current information of the booster motor M3 (including _id3 and i _q3 ), the vehicle speed v of the electric vehicle, and the reference braking deceleration a of the electric vehicle _ref is input to the above-mentioned energy recovery control model (implemented by the ECU in Figure 1), and the voltage information of the motor is obtained by solving. It should be noted that the obtained voltage information of the motor includes the direct-axis voltage u _d1 and the quadrature-axis voltage u _q1 of the front drive motor M1 , the direct-axis voltage u _d2 and the quadrature-axis voltage u _q2 of the rear drive motor M2 , and the booster motor M3 The direct axis voltage u _d3 and the quadrature axis voltage u _q3 .

Step S202a2: Referring to FIG. 3 and FIG. 4, determine the first torque T _m1 output by the front drive motor M1 based on the direct axis voltage u _d1 and the quadrature axis voltage u _q1 of the front drive motor M1, based on the direct axis voltage u _d2 of the rear drive motor M2 and The quadrature axis voltage u _q2 determines the second torque T _m2 output by the rear drive motor M2, and determines the third torque T _m3 output by the assist motor M3 based on the direct axis voltage u _d3 and the quadrature axis voltage u _q3 of the assist motor M3.

Furthermore, while the first torque T _m1 is output by the front drive motor M1, the front drive motor M1 can also generate the first energy P _M1 . Similarly, while the rear drive motor M2 outputs the second torque T _m2 , the rear drive motor M3 can also generate the second energy P _M1 . It should be noted that the front-drive motor M1 and the rear-drive motor M2 belong to drive motors, and the motors will generate energy (ie, the first energy P _M1 and the second torque T _m2 ) while outputting torque (ie, the first torque T _m1 and the second torque T m2 ). Two energy P _M2 ). The booster motor M3 is coupled with the braking system, so the booster motor M3 only outputs torque (ie, the third torque T _m3 ), and does not generate energy.

Step S202a3: Based on the torque output by the motor, control the vehicle to brake through the braking system of the electric vehicle, and store the energy generated by the motor into the power battery.

Further, referring to FIGS. 3 and 4 , according to the first torque T _m1 output by the front-drive motor M1 , the feedback torque T _mf of the front wheels is generated by the first transmission mechanism G(gear) 1 . At the same time, according to the second torque T _m2 output by the rear drive motor M3 , the feedback torque T _mr of the rear wheels is generated through the second transmission mechanism G(gear) 2 .

Still further, referring to FIG. 3 and FIG. 4 , the third torque T _m3 output by the booster motor M3 pushes the piston of the master cylinder MC (master cylinder) in the braking system B2 to build up pressure (that is, the output of the master cylinder MC). Master cylinder oil pressure P _c ). Then the master cylinder oil pressure P _c pushes the brake wheel cylinder FC (front cylinder) in the front wheel brake to generate the braking torque T _hf of the front wheel, and the master cylinder oil pressure P _c pushes the brake wheel cylinder RC in the rear wheel brake (rear cylinder) produces a rear wheel braking torque T _hr .

Further, the front wheel is controlled to brake by the feedback torque T _mf of the front wheel and the braking torque T _hf of the front wheel, and the rear wheel is controlled according to the feedback torque T _mr of the rear wheel and the braking torque T _hr of the rear wheel. brake. At the same time, the above-mentioned first energy P _M1 and second energy P _M2 are stored in the power battery.

It can be understood that the feedback torque T _mf of the front wheel and the braking torque T _hf of the front wheel are used to control the front wheel to brake, and the rear wheel is controlled to perform braking according to the feedback torque T _mr of the rear wheel and the braking torque T _hr of the rear wheel. Braking, that is, controlling the electric vehicle EV (electric vehicle) in Figure 3 to brake.

It should be noted that the torque T _f of the front wheel can be obtained by superimposing the feedback torque T _mf of the front wheel and the braking torque T _hf of the front wheel, and then according to the torque T _f of the front wheel and the radius of the front wheel (that is, the preceding The radius _Re ) of the wheel obtains the braking force F _f1 applied by the front wheel brake to the front wheel, and then controls the front wheel to brake through the braking force F _f applied by the front wheel brake to the front wheel. It is also possible to superimpose the feedback torque T _mr of the rear wheel and the braking torque T _hr of the rear wheel to obtain the torque _T _r of the rear wheel. _Re ) obtains the braking force _Fr1 applied by the rear wheel brake to the rear wheel, and then controls the rear wheel to brake through the braking force _Fr applied to the rear wheel by the rear wheel brake.

In the embodiment of the present application, the direct-axis voltage u _d1 and the quadrature-axis voltage u _q1 of the front-drive motor M1 obtained through the energy recovery controller directly act on the front-drive motor M1, and the direct-axis voltage u _d2 and the quadrature-axis voltage u of the rear-drive motor M2 _q2 directly acts on the rear drive motor M2, and the direct axis voltage u _d3 and the quadrature axis voltage u _q3 of the assist motor M3 directly act on the assist motor M3, that is to say, the embodiment of the present application directly controls the front drive motor M1 and the rear drive motor M2 And the booster motor M3, and then through the front drive motor M1, the rear drive motor M2 and the booster motor M3, the electric vehicle can only be braked, or the electric vehicle can be braked and the braking energy recovery can be enabled. Compared with the indirect braking scheme using the lower-level controller (including the braking control unit and the motor control unit), it not only reduces the control link, shortens the braking time of the electric vehicle, but also reduces the control cost.

In another example, in the process of controlling the electric vehicle to brake (only controlling the electric vehicle to brake, not controlling the electric vehicle to turn on the braking energy recovery), the front drive motor M1 and the rear drive motor M2 do not rotate, and only power assist Motor M3 rotates. Therefore, the current information of the front drive motor M1 (including _id1 and i _q1 ), the electrical angular velocity ω _r1 of the front drive motor M1 , the current information of the rear drive motor M2 (including _id2 and i _q2 ), and the electrical angular velocity ω of the rear drive motor M2 _{Both r2} are 0, and the current information (including i _d3 and i _q3 ) and the electrical angular velocity ω _r3 of the booster motor M3 are not 0.

As shown in FIG. 5 , the process 500 of controlling the electric vehicle to brake (only controlling the electric vehicle to brake, not controlling the electric vehicle to enable braking energy recovery) can be implemented through the following steps S202b1 to S202b3.

Step S202b1: Referring to FIG. 3 and FIG. 5, compare the electrical angular velocity ω _r1 of the front drive motor M1, the electrical angular velocity ω _r2 of the rear drive motor M2, the electrical angular velocity ω _r3 of the assist motor M3, and the current information of the front drive motor M1 (including _id1 and i _q1 ), the current information of the rear drive motor M2 (including _id2 and i _q2 ), the current information of the booster motor M3 (including _id3 and i _q3 ), the vehicle speed v of the electric vehicle, and the reference braking deceleration a of the electric vehicle _ref inputs the energy recovery control model and solves to obtain the voltage information of the motor.

It should be noted that, because only during the braking process, the front drive motor M1 and the rear drive motor M2 do not rotate, and the booster motor M3 rotates, the current information of the front drive motor M1 (including _id1 and i _q1 ), the electrical angular velocity ω of the front drive motor M1 _r1 , the current information of the rear drive motor M2 (including _id2 and i _q2 ) and the electrical angular velocity ω _r2 of the rear drive motor M2 are all 0, and the current information of the assist motor M3 (including _id3 and i _q3 ) and the electrical angular velocity ω _r3 not 0. Therefore, it can be considered that the direct-axis current i _d3 , the quadrature-axis current i _q3 and the electrical angular velocity ω _r3 of the booster motor M3 , the vehicle speed v of the electric vehicle, and the reference braking deceleration a _ref of the electric vehicle are input to the energy recovery control model.

It should also be noted that the obtained voltage information of the motor includes the direct axis voltage u _d1 and the quadrature axis voltage u _q1 of the front drive motor M1 , the direct axis voltage u _d2 and the quadrature axis voltage u _q2 of the rear drive motor M2 , and the booster motor The direct axis voltage u _d3 and the quadrature axis voltage u _q3 of M3. However, due to the current information of the front drive motor M1 (including _id1 and i _q1 ), the electrical angular velocity ω _r1 of the front drive motor M1, the current information of the rear drive motor M2 (including _id2 and i _q2 ) and the electrical angular velocity ω of the rear drive motor M2 _r2 is all 0, so the direct-axis voltage u _d1 and quadrature-axis voltage u _q1 of the front-drive motor and the direct-axis voltage u _d2 and quadrature-axis voltage u _q2 of the rear-drive motor M2 are all 0, and the direct-axis voltage of the booster motor M3 is 0. The voltage u _d3 and the quadrature axis voltage u _q3 are not zero. Therefore, it can be considered that the voltage information of the motor obtained by the solution is only the direct-axis voltage u _d3 and the quadrature-axis voltage u _q3 of the booster motor M3 .

Step S202b2: Referring to FIG. 3 and FIG. 5 , determine the third torque T _m3 output by the assisting motor M3 according to the direct-axis voltage u _d3 and the quadrature-axis voltage u _q3 of the assisting motor M3.

It should be noted that since the direct axis voltage u _d1 of the front drive motor, the quadrature axis voltage u _q1 of the front drive motor, the direct axis voltage u _d2 of the rear drive motor M2 and the quadrature axis voltage u _q2 of the rear drive motor M2 are all 0, the power assist The direct-axis voltage u _d3 and the quadrature-axis voltage u _q3 of the motor M3 are not 0, so the first torque T _m1 output by the front drive motor M1 and the second torque T _m2 output by the rear drive motor M2 are both 0. The third moment T _m3 is not zero.

Step S202b3 : Referring to FIG. 3 and FIG. 5 , based on the third torque T _m3 output by the booster motor M3 , the braking system of the electric vehicle is used to control the vehicle to brake.

Further, still referring to FIG. 3 and FIG. 5 , the third torque T _m3 output by the booster motor M3 pushes the piston of the master cylinder DAP in the braking system B2 to build up pressure (ie, the DAP outputs the master cylinder oil pressure P _c ). Then the master cylinder oil pressure P _c pushes the brake wheel cylinder FC in the front wheel brake to generate the braking torque T _hf of the front wheel, and the master cylinder oil pressure P _c pushes the brake wheel cylinder RC in the rear wheel brake to generate the braking torque T hf of the rear wheel braking torque T _hr .

Furthermore, the front wheels are controlled to perform braking according to the braking torque T _hf of the front wheels, and the rear wheels are controlled to be braked based on the braking torque T _hr of the rear wheels.

It should be noted that the braking force F _f2 applied by the front wheel brake to the front wheel is obtained according to the braking torque T _hf of the front wheel and the radius of the front wheel (ie, the radius _Re of the wheel above), and then applied to the front wheel through the front wheel brake. The braking force F _f2 of the front wheel controls the braking of the front wheel. The braking force F _r2 applied by the rear wheel brake to the rear wheel can also be obtained according to the braking torque T _hr of the rear wheel and the radius of the rear wheel (ie, the radius _Re of the wheel above), and then applied to the rear wheel through the rear wheel brake. The braking force F _r2 controls the rear wheels to brake.

It can be understood that, in the process of realizing the simultaneous braking and energy recovery of the electric vehicle from steps 202a1 to 202a3, the front-drive motor M1, the rear-drive motor M2, the booster motor M3 and the ECU are powered by the power battery B1. M1 and the rear drive motor M2 can generate energy, and the generated energy will be stored in the power battery B1.

It can also be understood that in the process of controlling the electric vehicle to brake in steps 202b1 to 202b3, the front-drive motor M1 and the rear-drive motor M2 do not generate energy, and the power battery B1 is used for the front-drive motor M1, the rear-drive motor M2, and the booster motor. M3 and ECU power supply.

FIG. 6 is a schematic flowchart of a vehicle braking method provided by an embodiment of the present application, and the process 600 may be implemented through the following steps S601 to S604.

Step S601: Obtain the state of charge SOC of the power battery on the electric vehicle.

In a possible implementation manner, according to the external characteristics of the power battery, in the embodiment of the present application, the discharge experiment method, the open circuit voltage method, the ampere-hour integration method, the Kalman filter method, the neural network method and other methods can be used to obtain the remaining power of the power battery. capacity. After that, according to the definition of the remaining capacity of the power battery and the state of charge SOC, the state of charge SOC of the power battery is obtained.

Step S602: Acquire state information of the motor and state information of the electric vehicle.

For example, obtain the electrical angular velocity of the front drive motor M1, the electrical angular velocity of the rear drive motor M2, the electrical angular velocity of the assist motor M3, the current information of the front drive motor M1, the current information of the rear drive motor M2, and the current information of the assist motor M3.

For another example, the vehicle speed of the electric vehicle and the reference braking deceleration of the electric vehicle are obtained.

Step S603: Build an energy recovery control model based on the state information of the motor and the state information of the electric vehicle.

In a possible implementation manner, as shown in FIG. 7 , the process 700 of constructing an energy recovery control model may be constructed according to the following steps S703a to S703e.

Step S703a: Determine the relationship between the torque of the wheel and the current information of the motor based on the electromagnetic torque equation of the motor, the mechanical equation of the motor, and the state equation of the braking system.

Step S703b: Determine the state equation of the electric vehicle based on the relationship between the torque of the wheel and the current information of the motor, the longitudinal dynamics equation of the electric vehicle, and the voltage equation of the motor.

Step S703c: Determine the actual braking deceleration and wheel torque of the electric vehicle based on the state equation of the electric vehicle and the current information of the motor.

Step S703d: Based on the actual braking deceleration of the electric vehicle and the torque of the wheels, three objective functions in total, the first objective function, the second objective function and the third objective function of the energy recovery control model are determined.

Wherein, the first objective function takes the trackable reference braking deceleration of the electric vehicle as the target, and is determined based on the actual braking deceleration of the electric vehicle. The second objective function takes the actual front and rear wheel braking force distribution ratio to meet the ideal front and rear wheel braking force distribution ratio as the goal, and is determined based on the torque of the wheels. The third objective function is to minimize the braking power of the braking system and is determined based on the torque of the wheels.

Step S703e: Determine the objective function of the energy recovery control model according to the first objective function, the second objective function and the third objective function, and determine the constraints of the energy recovery control model.

In a possible implementation manner, the first weighting coefficient of the first objective function, the second weighting coefficient of the second objective function, and the third weighting coefficient of the third objective function may be set first; then the first weighting coefficient, The second weighting coefficient and the third weighting coefficient weight the three objective functions, and take the minimum value of the weighted function as the goal to obtain the objective function of the energy recovery control model.

Exemplarily, in order to achieve the minimum weighted function value, the constraints of the energy recovery control model may include voltage constraints and voltage increment constraints.

It should be noted that in the above step S703a, the electromagnetic torque equation of the motor, the mechanical equation and the state equation of the braking system, the relationship between the torque of the wheel and the current information of the motor, the longitudinal dynamics equation of the electric vehicle, and the voltage equation of the motor , the state equation of the electric vehicle, the three objective functions, the objective function of the energy recovery control model, the voltage constraint and the voltage increment constraint can all be expressed by formulas, and the corresponding formulas can be found in the previous introduction, which is not repeated in the embodiments of this application.

Step S604: Determine whether the state of charge SOC obtained in step S601 is greater than the preset state of charge threshold (0.90 is taken as an example in the embodiment of this application). If the state of charge SOC obtained in step S601 is greater than 0.90, follow steps S605a to S605a to S605c controls the electric vehicle to brake (that is, only controls the electric vehicle to brake, and does not control the electric vehicle to turn on the braking energy recovery). The state of charge SOC obtained in step S601 is less than or equal to 0.90, and the electric vehicle is controlled to perform braking and turn on braking energy recovery according to the following steps S605a' to S605c'.

In a possible implementation manner, steps S605a to S605c may be implemented through the following processes.

Step S605a: Input the respective electrical angular velocities of the front drive motor M1, the rear drive motor M2 and the booster motor M3, the current information (direct axis current and quadrature axis current) of the three motors, the vehicle speed of the electric vehicle and the reference braking deceleration step The energy recovery control model constructed by 503 is solved to obtain the respective voltage information of the three motors (including the direct-axis voltage and the quadrature-axis voltage).

It should be noted that since the electric vehicle only performs braking, the front drive motor M1 and the rear drive motor M2 do not rotate, and only the booster motor M3 rotates. Therefore, only the electrical angular velocity of the booster motor M3 and the booster motor M3 are equivalent to the input energy recovery control model. The direct-axis current, the quadrature-axis current of the booster motor M3, the vehicle speed of the electric vehicle, and the reference braking deceleration of the electric vehicle. The voltage information obtained by solving the energy recovery control model is only the direct-axis voltage of the booster motor M3 and the quadrature-axis voltage of the booster motor M3.

Step S605b: Determine the third torque output by the assisting motor M3 based on the direct-axis voltage and the quadrature-axis voltage of the assisting motor M3.

Step 605c: Based on the third torque output by the booster motor M3, control the electric vehicle to perform braking through the braking system of the electric vehicle.

In another possible implementation manner, steps 605a' to 605c' can be implemented through the following processes.

Step S605a': Input the respective electrical angular velocities of the front drive motor M1, the rear drive motor M2 and the booster motor M3, the current information (direct-axis current and quadrature-axis current) of the three motors, the vehicle speed of the electric vehicle and the reference braking deceleration as input The energy recovery control model constructed in step S503 obtains the respective voltage information (including the direct-axis voltage and the quadrature-axis voltage) of the three motors.

Step S605b': Determine the respective torques of the three motors and the energy generated by the front drive motor M1 and the rear drive motor M2 according to the respective voltage information of the three motors.

Step S605c': Based on the torques output by the three motors (ie, the first torque, the second torque, and the third torque), the electric vehicle is controlled to brake through the braking system of the electric vehicle, and the front-drive motor M1 and the rear-drive motor are braked. The energy (ie, the first energy and the second energy) generated by the motor M2 is stored in the power battery.

FIG. 8 is a schematic structural diagram of a vehicle braking device provided by an embodiment of the present application. As shown in FIG. 8 , the vehicle braking device 800 provided in this embodiment of the present application may include an acquisition module 801 and a control module 802. The acquisition module 801 is used to acquire the state of charge SOC of the power battery on the electric vehicle; the control module 802 is used to control the electric vehicle to brake when the state of charge SOC is greater than a preset state of charge threshold; When the state of charge SOC is less than or equal to the state of charge threshold, the electric vehicle is controlled to perform braking and braking energy recovery is enabled.

The vehicle braking device 800 shown in FIG. 8 can determine whether it is necessary to control the vehicle to brake while controlling the vehicle to turn on the braking energy recovery through the state of charge SOC of the power battery, that is, according to the state of charge SOC, the electric vehicle can only be The control of braking, or the control of electric vehicle braking and opening of braking energy recovery, realizes the control and reuse of energy, and the recovered energy can effectively increase the battery life of the electric vehicle and realize energy saving and emission reduction. In addition, when the electric vehicle needs to be braked, the electric vehicle can switch between only braking and braking and energy recovery at the same time, which can effectively increase the battery life of the electric vehicle without affecting the braking of the electric vehicle. ability.

As shown in FIG. 9 , the vehicle braking device 800 may further include a determination module 803 for determining whether the acquired state of charge SOC is greater than a preset state of charge threshold.

It should be noted that the state of charge SOC of the power battery can be obtained according to the external characteristics of the power battery (such as parameters such as internal resistance, open circuit voltage, temperature, current, etc. of the power battery). For the detailed process of obtaining the state of charge SOC, please refer to the introduction in the preceding vehicle braking method, which is not repeated in this application.

In addition, the above-mentioned state-of-charge threshold can be set according to the rated capacity of the power battery. Of course, different state-of-charge thresholds can also be set according to the usage time of the power battery.

In an example, the above obtaining module 801 is further configured to: obtain the state information of the motors on the electric vehicle (that is, the three motors mentioned above) and the state information of the electric vehicle.

Further, the state information of the three motors includes electrical angular velocities of the three motors and/or current information of the three motors.

The electrical angular velocities of the three motors include the respective electrical angular velocities of the three single machines mentioned above, and may also include the respective direct-axis currents and quadrature-axis currents of the three motors.

Among them, the reference braking deceleration of the electric vehicle can be obtained according to the brake pedal stroke collected by the stroke sensor and through the longitudinal dynamics equation of the electric vehicle.

As shown in FIG. 10 , the vehicle braking device 800 further includes a modeling module 804 that can be used to construct an energy recovery control model.

Further, the energy recovery control model may include objective functions and constraints. The objective function may include a first objective function, a second objective function and a third objective function, and the constraints may include voltage constraints and/or voltage increment constraints.

In a possible implementation manner, the modeling module 804 constructs an energy recovery control model through the following steps S801a' to S801e'.

Step S801a': The modeling module determines the relationship between the torque of the wheel and the current information of the motor based on the electromagnetic torque equation of the motor, the mechanical equation of the motor, and the state equation of the braking system.

It should be explained that the electromagnetic torque equation, the mechanical equation and the state equation of the braking system can refer to the previous formulas. As described above, the relationship between the torque of the wheel and the current information of the three motors includes the relationship between the braking torque of the front wheel and the quadrature current of the booster motor M3, the braking torque of the rear wheel and the torque of the booster motor M3 The relationship between the quadrature axis current, the relationship between the feedback torque of the front wheel and the quadrature axis current of the front drive motor M1, and the relationship between the feedback torque of the rear wheel and the quadrature axis current of the rear drive motor M2. For these four relationships, reference may be made to the foregoing formulas, which will not be described in detail in this application.

Step S801b': Determine the state equation of the vehicle based on the relationship between the torque of the wheel and the current information of the three motors, the longitudinal dynamics equation of the electric vehicle, and the voltage equation of the motor.

It should be noted that the relationship between the torque of the wheel and the current information of the three motors in step S801b' is the four relationships in step S801a'. In addition, the longitudinal dynamics equation of the electric vehicle and the voltage equation of the motor can also refer to the previous formulas.

Step S801c': Determine the actual braking deceleration of the vehicle and the torque of the wheels based on the state equation of the vehicle and the current information of the motor.

In a possible implementation manner, the actual braking deceleration of the electric vehicle and the torque of the wheels (including the braking torque of the front wheels, the braking torque of the rear wheels, the feedback torque of the front wheels, and the feedback torque of the rear wheels) can be The direct-axis current and the quadrature-axis current of the three motors obtained by the obtaining module 701 are obtained by combining the state equation of the electric vehicle and the above four relationships.

Step S801d': According to the actual braking deceleration of the electric vehicle and the torque of the wheel, three objective functions in total, the first objective function, the second objective function and the third objective function of the energy recovery control model are obtained.

As described above, the first objective function is determined based on the actual braking deceleration of the electric vehicle, aiming at the trackable reference braking deceleration of the electric vehicle. The second objective function is determined based on the torque of the wheels, with the actual front and rear wheel braking force distribution ratio meeting the ideal front and rear wheel braking force distribution ratio as the goal. The third objective function takes the minimum braking power of the braking system as the goal, and is determined based on the torque of the wheels.

On the one hand, the above-mentioned first objective function is aimed at tracking the reference braking deceleration of the electric vehicle, which can ensure the smoothness of the braking of the electric vehicle and improve the driving experience. On the other hand, the above-mentioned second objective function expresses the difference between the actual front and rear wheel braking force distribution ratio and the ideal front and rear wheel braking force distribution ratio with the goal that the actual front and rear wheel braking force distribution ratio satisfies the ideal front and rear wheel braking force distribution ratio. The smaller the absolute value of the deviation, the better, that is, to make the actual front and rear wheel braking force distribution ratio meet the requirements of ECE regulations as much as possible to ensure the safety of electric vehicle braking. On the other hand, the third objective function takes the minimum braking power of the braking system as the goal, which can indicate that the absolute value of the deviation between the actual braking power and the target braking power is as small as possible, so that the front drive motor M1 and the rear drive motor M2 are better. In the process of regenerative braking, the more energy is generated, the maximum energy recovery can be achieved.

Step S801e': Determine the objective function of the energy recovery control model according to the first objective function, the second objective function and the third objective function, and determine the constraints of the energy recovery control model.

In a possible implementation manner, in the process of determining the objective function of the energy recovery control model through step 801e', the above-mentioned modeling module 804 may be based on a preset weighting coefficient (including the first weighting coefficient of the first objective function) , the second weighting coefficient of the second objective function and the 3rd weighting coefficient of the 3rd objective function) to the first objective function, the second objective function and the 3rd objective function are weighted, and take the function value after the weighting as the minimum target, The objective function of the energy recovery control model is obtained.

It is understandable that the modeling module takes the reference braking deceleration of the electric vehicle and the ideal front and rear wheel braking force distribution ratio as the tracking target, and takes the actual braking power output by the braking system as 0 as the optimization target, which not only improves the braking performance. The smoothness and safety of the movement, and the maximum energy recovery is achieved.

As described above, in order to achieve the goal of minimizing the weighted function value, the constraints of the energy recovery control model may include voltage constraints and/or voltage increment constraints.

It should be explained that the respective expressions of the three objective functions in the above-mentioned step S801d', the objective function and constraint conditions of the energy recovery control model in the step S801e' can all refer to the relevant formulas above, which are not repeated in this application.

On the basis that the modeling module 804 completes the modeling of the energy recovery control model, the control module 802 can combine the electrical angular velocities of the three motors obtained by the obtaining module 801 , the respective direct-axis and quadrature-axis currents of the three motors, and the electric vehicle The vehicle speed and the reference braking deceleration of the electric vehicle are used to control the electric vehicle to perform braking and enable braking energy recovery in the embodiment of the present application.

In an example, the control module 802 implements braking and energy recovery of the electric vehicle at the same time according to the following steps S802a1 to S802a3.

Step S802a1: Referring to FIG. 3, the control module 802 compares the electrical angular velocity ω r1 of the front drive motor M1, the electrical angular velocity ω _r2 of the rear drive motor M2, the electrical angular velocity ω _r3 of the assist motor M3, the _id1 and i _q1 of the _front drive motor M1, The _id2 and i _q2 of the rear drive motor M2, the _id3 and i _q3 of the booster motor M3, the vehicle speed v of the electric vehicle and the reference braking deceleration a _ref of the electric vehicle are input into the energy recovery control model, and the direct current of the front drive motor M1 is obtained by solving the The shaft voltage u _d1 and the quadrature axis voltage u _q1 , the direct axis voltage u _d2 and the quadrature axis voltage u _q2 of the rear drive motor M2, and the direct axis voltage u _d3 and the quadrature axis voltage u _q3 of the booster motor M3. .

Step S802a2: Continuing to refer to FIG. 3, the control module 802 determines the first torque T _m1 output by the front drive motor M1 based on u _d1 and u _q1 , and determines the second torque T _m2 output by the rear drive motor M2 based on u _d2 and u _q2 , and based on u d2 and u q2. u _d3 and u _q3 determine the third torque T _m3 output by the booster motor M3.

In addition to determining T _m1 , T _m2 and T _m3 by the control module 802 , the control module 802 also needs to determine the first energy P _M1 generated in the process of the first torque T _m1 output by the front-drive motor M1, and the rear-drive motor M2 is outputting the second energy P M1 . The second energy P _M2 generated during the torque T _m2 .

Step S802a3 : Still referring to FIG. 3 , the control module 802 generates the feedback torque T _mf of the front wheel through the first transmission mechanism G1 according to T _m1 . At the same time, the control module 802 generates the feedback torque T _mr of the rear wheel through the second transmission mechanism G2 according to T _m2 . The piston of the master cylinder DAP in the braking system B2 is pushed through T _m3 to build up the pressure (ie, the DAP outputs the master cylinder oil pressure P _c ). Then the master cylinder oil pressure P _c pushes the brake wheel cylinder FC in the front wheel brake to generate the braking torque T _hf of the front wheel, and the master cylinder oil pressure P _c pushes the brake wheel cylinder RC in the rear wheel brake to generate the braking torque T hf of the rear wheel braking torque T _hr .

Further, the control module 802 realizes the control of braking the front wheel by superimposing T _mf and T _hf , and the control module 802 realizes the control of braking the rear wheel by superimposing T _mr and T _hr . At the same time, the control module 802 stores the above-mentioned _PM1 and _PM2 into the power battery.

The above-mentioned control module 802 directly acts on u _d1 and u _q1 on the front drive motor M1, directly acts on u _d2 and u _q2 on the rear drive motor M2, and acts on u _d3 and u _q3 directly on the booster motor M3, that is to say, the vehicle system The driving device 700 directly controls the front-drive motor M1, the rear-drive motor M2, and the booster motor M3, and then realizes the control that the electric vehicle only performs braking through the front-drive motor M1, the rear-drive motor M2, and the booster motor M3, or realizes that the electric vehicle performs braking and Control of braking energy recovery. Compared with the indirect braking scheme using the lower-level controller, it not only reduces the control link, shortens the braking time of the electric vehicle, but also reduces the control cost.

In another example, the control module 802 implements the braking of the electric vehicle according to the following steps S802b1 to S802b3.

Step S802b1: The control module 802 inputs the electrical angular velocity ω _r3 of the booster motor M3, the direct-axis current _id3 and quadrature-axis current i _q3 of the booster motor M3, the vehicle speed v of the electric vehicle, and the reference braking deceleration a _ref of the electric vehicle into energy The recovery control model is solved, and the direct-axis voltage u _d3 and the quadrature-axis voltage u _q3 of the booster motor M3 are obtained. .

Step S802b2: The control module 802 determines the third torque T _m3 output by the assisting motor M3 according to u _d3 and u _q3 .

Step S802b3: Based on T _m3 , the control module 802 controls the electric vehicle to brake through the braking system of the electric vehicle.

Further, the piston of the master cylinder DAP in the braking system B2 is pushed to build up pressure through T _m3 (ie, the DAP outputs the master cylinder oil pressure P _c ). Then the master cylinder oil pressure P _c pushes the brake wheel cylinder FC in the front wheel brake to generate the braking torque T _hf of the front wheel, and the master cylinder oil pressure P _c pushes the brake wheel cylinder RC in the rear wheel brake to generate the braking torque T hf of the rear wheel braking torque T _hr .

Further, the front wheels are controlled for braking according to _Thf , and the rear wheels are controlled for braking based on _Th .

It should be noted that, since the front drive motor M1 and the rear drive motor M2 do not rotate and the booster motor M3 rotates only during the braking process, it can be considered that only the direct-axis current of the booster motor M3 is input to the energy recovery control model in step S802b1. i _d3 , quadrature axis current i _q3 and electrical angular velocity ω _r3 , vehicle speed v of the electric vehicle, and reference braking deceleration a _ref of the electric vehicle.

It can be understood that the direct-axis voltage u _d1 and the quadrature-axis voltage u _q1 of the front drive motor and the direct-axis voltage u _d2 and the quadrature-axis voltage u _q2 of the rear drive motor M2 obtained by the solution in step S802b1 are all 0, and the direct-axis voltage of the assist motor M3 is 0. The voltage u _d3 and the quadrature axis voltage u _q3 are not zero. Therefore, it can be considered that the voltage information of the motor obtained by the solution is only the direct-axis voltage u _d3 and the quadrature-axis voltage u _q3 of the booster motor M3 .

It can also be understood that, in the process of realizing that the electric vehicle only brakes in steps S802b1 to S802b3, the front drive motor M1 and the rear drive motor M2 will not generate energy, and the power battery B1 is used for the front drive motor M1, the rear drive motor M2, and the power assist. Motor M3 and ECU power supply.

Referring to FIG. 11 , the vehicle braking device 1100 provided in this embodiment of the present application may include a collection module 1101 and a braking system 1102 , and the collection module 1101 is coupled to the braking system 1102 . The acquisition module 1101 is used to acquire the state of charge SOC of the power battery on the vehicle. The braking system 1102 is used to control the electric vehicle to brake when the state of charge SOC is greater than a preset state of charge threshold; and is also used to control the electric vehicle to brake when the state of charge SOC is less than or equal to the state of charge threshold And turn on the braking energy recovery.

Further, as shown in FIG. 12 , the vehicle braking device 1100 further includes an energy recovery controller 1103 . The energy recovery controller 1103 is coupled to the harvesting module 1101 and the braking system 1102 . Wherein, the acquisition module 1101 is further used for: acquiring the state information of the motor on the electric vehicle and the state information of the electric vehicle; the energy recovery controller 1103 is used for: determining the voltage of the motor according to the state information of the motor and the state information of the electric vehicle. The braking system 1102 is also used to: control the electric vehicle to perform braking according to the voltage of the motor, or control the electric vehicle to perform braking and enable braking energy recovery.

In a possible implementation, the acquisition module 1101 may include at least one sensor. In the embodiment of the present application, multiple sensors are provided.

For example, the acquisition module 1101 may be provided with a current sensor. The current sensor is used to collect the three-phase currents of the front-drive motor M1, the rear-drive motor M2 and the booster motor M3 (the three-phase current is subjected to coordinate transformation (such as Parker transformation), and the respective direct-axis current and quadrature-axis current of the three motors can be obtained. ). It should be noted that the three-phase currents of the three motors can be collected through one current sensor, and the three-phase currents of the three motors can also be collected through three sensors respectively.

For another example, the collection module 1101 may be provided with a vehicle speed sensor. The vehicle speed sensor is used to collect the vehicle speed of the electric vehicle.

For another example, the collection module 1101 may be provided with a travel sensor. The travel sensor is used to collect the travel of the brake pedal (the reference braking deceleration of the electric vehicle can be obtained through the travel of the brake pedal and the longitudinal dynamics equation of the electric vehicle).

In a possible implementation manner, an embodiment of the present application provides an electronic device, and the electronic device may include at least one processor and a memory. At least one processor can call all or part of the computer program in the memory to control and manage the actions of the vehicle braking device 800 or the vehicle braking device 1100, for example, can be used to support the vehicle braking device 800 or the vehicle braking device 1100 to execute The steps performed by each of the above modules. The memory may be used to support the execution of the vehicle braking device 800 or the vehicle braking device 1100 in the above-described embodiments to store one or more stored program codes, data, and the like. The processor may implement or execute various exemplary logic modules described in conjunction with the embodiments of the present application, which may be a combination of one or more microprocessors that realize computing functions, such as including but not limited to a central processing unit and a controller, etc. . In addition, the processor may also include other programmable logic devices, transistor logic devices, or discrete hardware components, or the like. The memory may include random access memory (RAM), read only memory ROM, and the like. The random access memory may include volatile memory (such as SRAM, DRAM, DDR (Double Data Rate SDRAM, Double Data Rate SDRAM) or SDRAM, etc.) and non-volatile memory. Data (such as the state of charge SOC of the power battery, etc.) and parameters required for the operation of the vehicle braking device 800 or the vehicle braking device 1100 and parameters generated by the operation of the vehicle braking device 700 or the vehicle braking device 1100 can be stored in the RAM. Intermediate data, output results of the vehicle braking device 800 or the vehicle braking device 1100 after operation, and the like. The read-only memory ROM may store an executable program of the vehicle braking device 800 or the vehicle braking device 1100 . Each of the above components can perform their own work by loading an executable program. The executable program stored in the memory may execute the vehicle braking method as shown in FIGS. 2 , 4 , 5 and 6 .

In another possible implementation manner, an embodiment of the present application provides a computer-readable storage medium, where an instruction is stored in the computer-readable storage medium, and when the instruction is run on a computer, it is used to execute and implement the above-mentioned embodiments. The vehicle braking method of the vehicle braking device 800 in the above, or the vehicle braking method of the vehicle braking device 1100 in the above-mentioned embodiment is implemented.

In yet another possible implementation manner, the embodiment of the present application provides a computer program product, and the computer program product contains instructions, when the instructions are executed on a computer or a processor, the computer or the processor is made to implement the above-mentioned embodiments. The vehicle braking method of the vehicle braking device 800, or the vehicle braking method implementing the vehicle braking device 1100 in the above embodiment.

It should be understood that, in various embodiments of the present application, the size of the sequence numbers of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its functions and internal logic, and should not be dealt with in the embodiments of the present application. implementation constitutes any limitation.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of this application.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described systems, devices and units may refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, which may be electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution, and the computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read only memory (Read Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited to this. should be covered within the scope of protection of this application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

A vehicle braking method, comprising:

Obtain the state of charge SOC of the power battery on the vehicle;

If the state of charge SOC is greater than a preset state of charge threshold, controlling the vehicle to perform braking;

If the state of charge SOC is less than or equal to the state of charge threshold, control the vehicle to perform braking and enable braking energy recovery.
The vehicle braking method according to claim 1, wherein after acquiring the state of charge (SOC) of the power battery on the vehicle, the method further comprises:

Obtain the state information of the motor on the vehicle and the state information of the vehicle;

The state information of the motor includes electrical angular velocity of the motor and/or current information of the motor;

The state information of the vehicle includes a vehicle speed and/or a reference braking deceleration of the vehicle.
The vehicle braking method according to claim 2, wherein the controlling the vehicle to perform braking and enabling braking energy recovery comprises:

Inputting the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solving to obtain the voltage information of the motor;

Determine the torque output by the motor and the energy generated by the motor based on the voltage information of the motor;

Based on the torque output by the electric motor, the vehicle is controlled to perform braking through the braking system of the vehicle, and the energy generated by the electric motor is stored in the power battery.
The vehicle braking method according to claim 2 or 3, wherein the controlling the vehicle to brake comprises:

Inputting the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solving to obtain the voltage information of the motor;

determining the torque output by the motor based on the voltage information of the motor;

Based on the torque output by the electric motor, the vehicle is controlled to perform braking through the braking system of the vehicle.
The vehicle braking method according to claim 3 or 4, wherein after acquiring the state of charge SOC of the power battery on the vehicle, the method further comprises:

determining the relationship between the torque of the wheels on the vehicle and the current information of the electric machine based on the electromagnetic torque equation of the electric machine, the mechanical equation of the electric machine and the state equation of the braking system;

determining a state equation of the vehicle based on the relationship between the torque of the wheel and the current information of the electric machine, the longitudinal dynamics equation of the vehicle, and the voltage equation of the electric machine;

determining the actual braking deceleration of the vehicle and the torque of the wheels based on the state equation of the vehicle and current information of the electric machine;

The first objective function of the energy recovery control model is determined based on the actual braking deceleration of the vehicle, and the second objective function and the third objective function of the energy recovery control model are determined based on the torque of the wheel, the The first objective function is that the vehicle can track the reference braking deceleration, and the second objective function is based on the distribution ratio of the braking force of the front wheel brake and the braking force of the rear wheel brake on the vehicle. The preset distribution ratio is the goal, and the third objective function is aimed at the minimum braking power of the braking system;

An objective function of the energy recovery control model is determined based on the first objective function, the second objective function and the third objective function, and constraints of the energy recovery control model are determined.
The vehicle braking method according to claim 5, wherein the motor comprises at least one of a first motor, a second motor and a third motor;

The relationship between the torque of the wheel and the current information of the motor satisfies the following formula:

In the formula, T hf represents the braking torque of the front wheel, T hr represents the braking torque of the rear wheel, T mf represents the feedback torque of the front wheel, T mr represents the feedback torque of the rear wheel, r 1 represents the piston diameter of the brake master cylinder in the braking system, r 2 represents the piston diameter of the brake wheel cylinder in the front wheel brake, r 3 represents the piston diameter of the brake wheel cylinder in the rear wheel brake diameter, μf is the friction coefficient of the brake disc in the brake of the front wheel, μr is the friction coefficient of the brake disc in the brake of the rear wheel, Re is the radius of the front wheel/rear wheel, N P1 is the The number of pole pairs of the first motor, N P2 represents the number of pole pairs of the second motor, N P3 represents the number of pole pairs of the third motor, ψ f1 represents the rotor flux linkage of the first motor, ψ f2 represents the rotor flux linkage of the second motor, ψ f3 represents the rotor flux linkage of the third motor, i q1 represents the quadrature axis current of the first motor, i q2 represents the quadrature axis current of the second motor , i q3 represents the quadrature axis current of the third motor, η 1 represents the transmission coefficient between the third motor and the piston push rod of the master cylinder, n f represents the first motor to the The transmission coefficient of the front wheel, n r represents the transmission coefficient of the second motor to the rear wheel.
The vehicle braking method according to claim 5 or 6, wherein the state equation of the vehicle is:

In the formula,
represents the first derivative of the direct axis current of the first motor,
represents the first derivative of the quadrature axis current of the first motor,
represents the first derivative of the direct axis current of the second motor,
represents the first derivative of the quadrature axis current of the second motor,
represents the first derivative of the direct axis current of the third motor,
represents the first derivative of the quadrature axis current of the third motor, a represents the braking deceleration of the vehicle,
represents the first-order differential of the vehicle speed, i d1 represents the direct-axis current of the first motor, i q1 represents the quadrature-axis current of the first motor, id2 represents the direct-axis current of the second motor, and i q2 represents the quadrature axis current of the second motor, i d3 represents the direct axis current of the third motor, i q3 represents the quadrature axis current of the third motor, R s1 represents the internal resistance of the first motor, R s2 represents the internal resistance of the second motor, R s3 represents the internal resistance of the third motor, L d1 represents the direct axis inductance of the first motor, L q1 represents the quadrature axis inductance of the first motor, L d2 represents the direct axis inductance of the second motor, L q2 represents the quadrature axis inductance of the second motor, L d3 represents the direct axis inductance of the third motor, and L q3 represents the quadrature axis inductance of the third motor , ω r1 represents the electrical angular velocity of the first motor, ω r2 represents the electrical angular velocity of the second motor, ω r3 represents the electrical angular velocity of the third motor, u d1 represents the direct axis voltage of the first motor, u q1 represents the quadrature axis voltage of the first motor, u d2 represents the direct axis voltage of the second motor, u q2 represents the quadrature axis voltage of the second motor, and u d3 represents the direct axis voltage of the third motor voltage, u q3 represents the quadrature axis voltage of the third motor, ψ f1 represents the rotor flux linkage of the first motor, ψ f2 represents the rotor flux linkage of the second motor, and ψ f3 represents the third motor. Rotor flux linkage, T hf represents the braking torque of the front wheel, T hr represents the braking torque of the rear wheel, T mf represents the feedback torque of the front wheel, T mr represents the feedback torque of the rear wheel, m veh represents the mass of the vehicle, Re represents the radius of the front/rear wheels, F air represents the air resistance of the vehicle, and F roll represents the rolling resistance of the vehicle.
The vehicle braking method according to any one of claims 5 to 7, wherein the first objective function is:

In the formula, J 1 represents the function value of the first objective function, a(k+i) represents the actual braking deceleration of the vehicle at the k+i th time, and a ref (k+i) represents the vehicle The reference braking deceleration at time k+i, P represents the total number of steps.
The vehicle braking method according to any one of claims 5 to 8, wherein the second objective function is:

In the formula, J 2 represents the function value of the second objective function, T mf (k+i) represents the feedback torque of the front wheel at the k+ith moment, and T hf (k+i) represents the front wheel The braking torque at the k+ith moment, T mr (k+i) represents the feedback torque of the rear wheel at the k+ith moment, T hr (k+i) represents the rear wheel at the k+ith moment The braking torque at the moment, Re represents the radius of the wheel, CF represents the preset distribution ratio, and P represents the total number of steps.
The vehicle braking method according to any one of claims 5 to 9, wherein the third objective function is:

In the formula, J 3 represents the function value of the third objective function, T hf (k+i) represents the braking torque of the front wheel at the k+i th time, T hr (k+i) represents the rear is the braking torque of the wheel at the k +ith moment, ωf (k+i) represents the angular velocity of the front wheel at the k+ith moment, and ωr (k+i) represents the rear wheel at the k+ith moment The angular velocity at the moment, P target represents the target braking power of the braking system, and P represents the total number of steps.
The vehicle braking method according to any one of claims 5 to 10, wherein the energy recovery is determined based on the first objective function, the second objective function and the third objective function The objective function of the control model, including:

The first objective function, the second objective function and the third objective function are weighted based on a preset weighting coefficient, and the objective of the energy recovery control model is determined with the minimum weighted function value as the objective function, the weighting coefficients include a first weighting coefficient of the first objective function, a second weighting coefficient of the second objective function, and a third weighting coefficient of the third objective function.
The vehicle braking method according to any one of claims 5 to 11, wherein the constraints of the energy recovery control model include voltage constraints and/or voltage increment constraints.
The vehicle braking method according to claim 12, wherein the voltage constraint is:

In the formula, u min1 represents the minimum voltage of the first motor, u max1 represents the maximum voltage of the first motor, u min2 represents the minimum voltage of the second motor, and u max3 represents the second motor. u min3 represents the minimum voltage of the third motor, u max3 represents the maximum voltage of the third motor, u d1 represents the direct axis voltage of the first motor, and u q1 represents the voltage of the first motor The quadrature axis voltage of a motor, u d2 represents the direct axis voltage of the second motor, u q2 represents the quadrature axis voltage of the second motor, u d3 represents the direct axis voltage of the third motor, and u q3 represents the the quadrature axis voltage of the third motor;

The voltage increment constraint is:

In the formula, ‖Δu d1 ‖ represents the direct-axis voltage increment of the first motor, ‖Δu q1 ‖ represents the quadrature-axis voltage increment of the first motor, and ‖Δu d1max ‖ represents the direct-axis voltage of the first motor The maximum value of the voltage increment, ‖Δu q1max ‖ represents the maximum value of the quadrature-axis voltage increment of the first motor, ‖Δu d2 ‖ represents the direct-axis voltage increment of the second motor, and ‖Δu q2 ‖ represents the The quadrature axis voltage increment of the two motors, ‖Δu d2max ‖ represents the maximum value of the direct axis voltage increment of the second motor, ‖Δu q2max ‖ represents the maximum value of the quadrature axis voltage increment of the second motor, ‖Δu d3 ‖ represents the direct-axis voltage increment of the third motor, ‖Δu q3 ‖ represents the quadrature-axis voltage increment of the third motor, ‖Δu d3max ‖ represents the maximum value of the direct-axis voltage increment of the third motor, ‖Δu q3max ‖ represents the maximum value of the quadrature axis voltage increment of the third motor.
The vehicle braking method according to any one of claims 6 to 13, wherein the determining the torque output by the motor and the energy generated by the motor based on the voltage information of the motor comprises:

The first torque output by the first motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the first motor, and the second torque output by the second motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the second motor. torque, and determine the third torque output by the third motor based on the direct-axis voltage and the quadrature-axis voltage of the third motor;

The first energy generated by the first motor is determined based on the first torque output by the first motor, and the second energy generated by the second motor is determined based on the second torque output by the second motor.
The vehicle braking method according to claim 14, characterized in that, based on the torque output by the motor, the vehicle is controlled to perform braking through the braking system of the vehicle, and the energy generated by the motor is used for braking. Stored in the power battery, including:

Determine the feedback torque of the front wheel based on the first torque output by the first motor, and determine the feedback torque of the rear wheel based on the second torque output by the second motor;

Based on the third torque output by the third motor, the braking of the front wheel is determined by the master brake cylinder, the brake wheel cylinder of the front wheel brake and the brake wheel cylinder of the rear wheel brake. the dynamic torque and the braking torque of the rear wheel;

The front wheels are controlled to perform braking based on the feedback torque of the front wheels and the braking torque of the front wheels, and the rear wheels are controlled to perform braking based on the feedback torque of the rear wheels and the braking torque of the rear wheels. brake;

The first energy generated by the first motor and the second energy generated by the second motor are stored in the power battery.
The vehicle braking method according to any one of claims 6 to 15, wherein the determining the torque output by the motor based on the voltage information of the motor comprises:

A third torque output by the third motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the third motor.
The vehicle braking method according to claim 16, wherein the controlling the vehicle to perform braking through the braking system of the vehicle based on the torque output by the motor comprises:

Based on the third torque output by the third motor, the braking of the front wheel is determined by the master brake cylinder, the brake wheel cylinder of the front wheel brake and the brake wheel cylinder of the rear wheel brake. the dynamic torque and the braking torque of the rear wheel;

The front wheels are controlled to be braked based on the braking torque of the front wheels, and the rear wheels are controlled to be braked based on the braking torque of the rear wheels.
The vehicle braking method according to any one of claims 1 to 17, wherein the vehicle is an electric vehicle.
The vehicle braking method according to claim 18, wherein the electric vehicle is an electric vehicle.
A vehicle braking device, comprising:

an acquisition module for acquiring the state of charge SOC of the power battery on the vehicle;

a control module, configured to control the vehicle to perform braking when the state-of-charge SOC is greater than a preset state-of-charge threshold; further configured to, when the state-of-charge SOC is less than or equal to the state-of-charge threshold, The vehicle is controlled to brake and brake energy recovery is turned on.
The vehicle braking device according to claim 20, wherein the acquisition module is further configured to:

Obtain the state information of the motor on the vehicle and the state information of the vehicle;

The state information of the motor includes electrical angular velocity of the motor and/or current information of the motor;

The state information of the vehicle includes a vehicle speed and/or a reference braking deceleration of the vehicle.
The vehicle braking device of claim 21, wherein the control module is configured to:

Inputting the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solving to obtain the voltage information of the motor;

Determine the torque output by the motor and the energy generated by the motor based on the voltage information of the motor;

Based on the torque output by the electric motor, the braking system of the vehicle is used to control the vehicle to perform braking, and the energy generated by the electric motor is stored in the power battery.
The vehicle braking device according to claim 21 or 22, wherein the control module is used for:

Inputting the state information of the motor and the state information of the vehicle into a pre-built energy recovery control model, and solving to obtain the voltage information of the motor;

determining the torque output by the motor based on the voltage information of the motor;

Based on the torque output by the electric motor, the vehicle is controlled to perform braking through the braking system of the vehicle.
The vehicle braking device according to claim 22 or 23, wherein the device further comprises a modeling module for:

determining the relationship between the torque of the wheels on the vehicle and the current information of the electric machine based on the electromagnetic torque equation of the electric machine, the mechanical equation of the electric machine and the state equation of the braking system;

determining a state equation of the vehicle based on the relationship between the torque of the wheel and the current information of the electric machine, the longitudinal dynamics equation of the vehicle, and the voltage equation of the electric machine;

determining the actual braking deceleration of the vehicle and the torque of the wheels based on the state equation of the vehicle and current information of the electric machine;

The first objective function of the energy recovery control model is determined based on the actual braking deceleration of the vehicle, and the second objective function and the third objective function of the energy recovery control model are determined based on the torque of the wheel, the The first objective function is that the vehicle can track the reference braking deceleration, and the second objective function is based on the distribution ratio of the braking force of the front wheel brake and the braking force of the rear wheel brake on the vehicle. The preset distribution ratio is the goal, and the third objective function is aimed at the minimum braking power of the braking system;

Determine the objective function of the energy recovery control model based on the first objective function, the second objective function and the third objective function, and determine the constraints of the energy recovery control model;

The motor includes at least one of a first motor, a second motor, and a third motor;

The relationship between the torque of the wheel and the current information of the motor satisfies the following formula:

In the formula, T hf represents the braking torque of the front wheel, T hr represents the braking torque of the rear wheel, T mf represents the feedback torque of the front wheel, T mr represents the feedback torque of the rear wheel, r 1 represents the piston diameter of the brake master cylinder in the braking system, r 2 represents the piston diameter of the brake wheel cylinder in the brake of the front wheel, r 3 represents the diameter of the brake wheel cylinder in the brake of the rear wheel Piston diameter, μf is the friction coefficient of the brake disc in the brake of the front wheel, μr is the friction coefficient of the brake disc in the brake of the rear wheel, Re is the radius of the front/rear wheel, N P1 represents the number of pole pairs of the first motor, N P2 represents the number of pole pairs of the second motor, N P3 represents the number of pole pairs of the third motor, ψ f1 represents the rotor flux linkage of the first motor, ψ f2 represents the rotor flux linkage of the second motor, ψ f3 represents the rotor flux linkage of the third motor, i q1 represents the quadrature axis current of the first motor, and i q2 represents the quadrature axis of the second motor Current, i q3 represents the quadrature axis current of the third motor, η 1 represents the transmission coefficient between the third motor and the piston push rod of the master cylinder, n f represents the first motor to the the transmission coefficient of the front wheel, n r represents the transmission coefficient of the second motor to the rear wheel;

The state equation of the vehicle is:

In the formula,
represents the first derivative of the direct axis current of the first motor,
represents the first derivative of the quadrature axis current of the first motor,
represents the first derivative of the direct axis current of the second motor,
represents the first derivative of the quadrature axis current of the second motor,
represents the first derivative of the direct axis current of the third motor,
represents the first derivative of the quadrature axis current of the third motor, a represents the braking deceleration of the vehicle,
represents the first-order differential of the vehicle speed, i d1 represents the direct-axis current of the first motor, i q1 represents the quadrature-axis current of the first motor, id2 represents the direct-axis current of the second motor, and i q2 represents the quadrature axis current of the second motor, i d3 represents the direct axis current of the third motor, i q3 represents the quadrature axis current of the third motor, R s1 represents the internal resistance of the first motor, R s2 represents the internal resistance of the second motor, R s3 represents the internal resistance of the third motor, L d1 represents the direct axis inductance of the first motor, L q1 represents the quadrature axis inductance of the first motor, L d2 represents the direct axis inductance of the second motor, L q2 represents the quadrature axis inductance of the second motor, L d3 represents the direct axis inductance of the third motor, and L q3 represents the quadrature axis inductance of the third motor , ω r1 represents the electrical angular velocity of the first motor, ω r2 represents the electrical angular velocity of the second motor, ω r3 represents the electrical angular velocity of the third motor, u d1 represents the direct axis voltage of the first motor, u q1 represents the quadrature axis voltage of the first motor, u d2 represents the direct axis voltage of the second motor, u q2 represents the quadrature axis voltage of the second motor, and u d3 represents the direct axis voltage of the third motor voltage, u q3 represents the quadrature axis voltage of the third motor, ψ f1 represents the rotor flux linkage of the first motor, ψ f2 represents the rotor flux linkage of the second motor, and ψ f3 represents the third motor. Rotor flux linkage, T hf represents the braking torque of the front wheel, T hr represents the braking torque of the rear wheel, T mf represents the feedback torque of the front wheel, T mr represents the feedback torque of the rear wheel, m veh represents the mass of the vehicle, Re represents the radius of the front wheel/rear wheel, F air represents the air resistance of the vehicle, and F roll represents the rolling resistance of the vehicle;

The first objective function is:

In the formula, J 1 represents the function value of the first objective function, a(k+i) represents the actual braking deceleration of the vehicle at the k+i th time, and a ref (k+i) represents the vehicle The reference braking deceleration at the k+ith moment, P represents the total number of steps;

The second objective function is:

In the formula, J 2 represents the function value of the second objective function, T mf (k+i) represents the feedback torque of the front wheel at the k+ith moment, and T hf (k+i) represents the front wheel The braking torque at the k+ith moment, T mr (k+i) represents the feedback torque of the rear wheel at the k+ith moment, T hr (k+i) represents the rear wheel at the k+ith moment the braking torque at the moment, Re represents the radius of the wheel, CF represents the preset distribution ratio, and P represents the total number of steps;

The third objective function is:

In the formula, J 3 represents the function value of the third objective function, T hf (k+i) represents the braking torque of the front wheel at the k+i th time, T hr (k+i) represents the rear is the braking torque of the wheel at the k +ith moment, ωf (k+i) represents the angular velocity of the front wheel at the k+ith moment, and ωr (k+i) represents the rear wheel at the k+ith moment the angular velocity at the moment, P target represents the target braking power of the braking system, and P represents the total number of steps;

The constraints of the energy recovery control model include voltage constraints and/or voltage increment constraints;

The voltage constraints are:

In the formula, u min1 represents the minimum voltage of the first motor, u max1 represents the maximum voltage of the first motor, u min2 represents the minimum voltage of the second motor, and u max3 represents the second motor. u min3 represents the minimum voltage of the third motor, u max3 represents the maximum voltage of the third motor, u d1 represents the direct axis voltage of the first motor, and u q1 represents the voltage of the first motor The quadrature axis voltage of a motor, u d2 represents the direct axis voltage of the second motor, u q2 represents the quadrature axis voltage of the second motor, u d3 represents the direct axis voltage of the third motor, and u q3 represents the the quadrature axis voltage of the third motor;

The voltage increment constraint is:

In the formula, ‖Δu d1 ‖ represents the direct-axis voltage increment of the first motor, ‖Δu q1 ‖ represents the quadrature-axis voltage increment of the first motor, and ‖Δu d1max ‖ represents the direct-axis voltage of the first motor The maximum value of the voltage increment, ‖Δu q1max ‖ represents the maximum value of the quadrature-axis voltage increment of the first motor, ‖Δu d2 ‖ represents the direct-axis voltage increment of the second motor, and ‖Δu q2 ‖ represents the The quadrature axis voltage increment of the two motors, ‖Δu d2max ‖ represents the maximum value of the direct axis voltage increment of the second motor, ‖Δu q2max ‖ represents the maximum value of the quadrature axis voltage increment of the second motor, ‖Δu d3 ‖ represents the direct-axis voltage increment of the third motor, ‖Δu q3 ‖ represents the quadrature-axis voltage increment of the third motor, ‖Δu d3max ‖ represents the maximum value of the direct-axis voltage increment of the third motor, ‖Δu q3max ‖ represents the maximum value of the quadrature axis voltage increment of the third motor.
The vehicle braking device of claim 24, wherein the modeling module is used to:

The first objective function, the second objective function and the third objective function are weighted based on a preset weighting coefficient, and the objective of the energy recovery control model is determined with the minimum weighted function value as the objective function, the weighting coefficients include a first weighting coefficient of the first objective function, a second weighting coefficient of the second objective function, and a third weighting coefficient of the third objective function.
The vehicle braking device according to claim 24 or 25, wherein the control module is used to:

The first torque output by the first motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the first motor, and the second torque output by the second motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the second motor. torque, and determine the third torque output by the third motor based on the direct-axis voltage and the quadrature-axis voltage of the third motor;

The first energy generated by the first motor is determined based on the first torque output by the first motor, and the second energy generated by the second motor is determined based on the second torque output by the second motor.
The vehicle braking device of claim 26, wherein the control module is configured to:

Determine the feedback torque of the front wheel based on the first torque output by the first motor, and determine the feedback torque of the rear wheel based on the second torque output by the second motor;

Based on the third torque output by the third motor, the braking of the front wheel is determined by the master brake cylinder, the brake wheel cylinder of the front wheel brake and the brake wheel cylinder of the rear wheel brake. the dynamic torque and the braking torque of the rear wheel;

The front wheels are controlled to perform braking based on the feedback torque of the front wheels and the braking torque of the front wheels, and the rear wheels are controlled to perform braking based on the feedback torque of the rear wheels and the braking torque of the rear wheels. brake;

The first energy generated by the first motor and the second energy generated by the second motor are stored in the power battery.
The vehicle braking device according to any one of claims 24 to 27, wherein the control module is configured to:

A third torque output by the third motor is determined based on the direct-axis voltage and the quadrature-axis voltage of the third motor.
The vehicle braking device of claim 28, wherein the control module is configured to:

Based on the third torque output by the third motor, the braking of the front wheel is determined by the master brake cylinder, the brake wheel cylinder of the front wheel brake and the brake wheel cylinder of the rear wheel brake. the dynamic torque and the braking torque of the rear wheel;

The front wheels are controlled to be braked based on the braking torque of the front wheels, and the rear wheels are controlled to be braked based on the braking torque of the rear wheels.
The vehicle braking device according to any one of claims 20 to 29, wherein the vehicle is an electric vehicle.
The vehicle braking device according to claim 30, wherein the electric vehicle is an electric vehicle.
A vehicle braking device, comprising:

The acquisition module is used to obtain the state of charge SOC of the power battery on the vehicle;

a braking system, configured to control the vehicle to perform braking when the state of charge SOC is greater than a preset state of charge threshold; further configured to control the vehicle to brake when the state of charge SOC is less than or equal to the state of charge threshold , control the vehicle to brake and turn on the braking energy recovery.
The vehicle braking device of claim 32, wherein the device further comprises an energy recovery controller coupled to the harvesting module and the braking system;

The acquisition module is further configured to: acquire the state information of the motor on the vehicle and the state information of the vehicle;

The energy recovery controller is used for: determining the voltage of the motor according to the state information of the motor and the state information of the vehicle;

The braking system is further used for: controlling the vehicle to perform braking according to the voltage of the electric motor, or controlling the vehicle to perform braking and enabling braking energy recovery.
An electronic device, comprising:

at least one processor;

memory for storing one or more programs;

The method as claimed in any one of claims 1 to 19 is implemented when the one or more programs are executed by the at least one processor.
A computer-readable storage medium storing instructions in the computer-readable storage medium, characterized in that, when the instructions are executed on a computer, they are used to execute the method described in any one of claims 1 to 19. method.
A computer program product comprising instructions, characterized in that, when the instructions are executed on a computer or a processor, the computer or the processor is made to implement any one of claims 1 to 19. one of the methods described.