WO2022048267A1

WO2022048267A1 - Acceleration slip regulation method for electric vehicle, and dual-motor four-wheel drive electric vehicle

Info

Publication number: WO2022048267A1
Application number: PCT/CN2021/102836
Authority: WO
Inventors: 吴爱彬; 张天强; 刘元治; 崔金龙; 周泽慧; 赵洋
Original assignee: 中国第一汽车股份有限公司
Priority date: 2020-09-07
Filing date: 2021-06-28
Publication date: 2022-03-10
Also published as: CN112026536A; CN112026536B

Abstract

An acceleration slip regulation method for an electric vehicle, comprising: obtaining actual wheel speeds of vehicle wheels, vehicle wheel steering angles, and yaw rate, lateral acceleration, and longitudinal acceleration of the vehicle; calculating vehicle target front and rear axle speeds according to the above parameters; calculating vehicle actual front and rear axle speeds according to the actual wheel speeds; and according to the vehicle target front and rear axle speeds and the vehicle actual front and rear axle speeds, calculating motor output anti-slip target torques to regulate axle speed deviations between the vehicle target front and rear axle speeds and the vehicle actual front and rear axle speeds. Also disclosed is a dual-motor four-wheel drive electric vehicle.

Description

Driving anti-skid control method of electric vehicle and dual-motor four-wheel drive electric vehicle

This disclosure claims the priority of a Chinese patent application with application number 202010929971.X filed with the China Patent Office on September 7, 2020, the entire contents of the above application are incorporated into this disclosure by reference.

technical field

The embodiments of the present application relate to a driving anti-skid control technology, for example, a driving anti-skid control method for an electric vehicle and a dual-motor four-wheel drive electric vehicle.

Background technique

Acceleration slip regulation (ASR) is an active safety system that can improve vehicle acceleration performance and ensure vehicle stability during vehicle driving. To ensure good adhesion between the tire and the ground, so as to obtain good driving performance and handling stability. The four-wheel drive electric vehicle in the related art controls the braking torque of the driving wheel through the driving anti-skid system or performs torque reduction control on the engine to prevent the driving wheel from excessively slipping during the acceleration process of the vehicle, which will affect the power output of the vehicle. , there are also problems such as poor starting driving stability and poor driving experience of the vehicle driver.

SUMMARY OF THE INVENTION

The present application provides a driving anti-skid control method for an electric vehicle and a dual-motor four-wheel-drive electric vehicle. By performing driving anti-skid control on the front and rear axle motors respectively, so as to coordinately limit the torque of the front and rear axle motors, and perform torque distribution on the front and rear axle motors, so that the whole The power output of the car remains unchanged, which improves the driving experience.

In a first aspect, an embodiment of the present application provides a driving anti-skid control method for an electric vehicle, the method comprising:

Obtain the actual wheel speed, wheel angle, vehicle yaw rate, vehicle lateral acceleration and vehicle longitudinal acceleration;

According to the actual wheel speed, the wheel angle, the yaw rate of the vehicle, the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle, calculate the front and rear target axle speeds of the vehicle;

Calculate the actual front and rear axle speeds of the vehicle according to the actual wheel speed;

According to the target front and rear axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle, the motor output anti-skid target torque is calculated to control the axle speed deviation between the front and rear target axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle.

Optionally, the anti-skid target torque includes a front-axle anti-skid target torque and a rear-axle anti-skid target torque; the method further includes:

Limiting the front axle demand torque according to the front axle anti-skid target torque so that the motor front axle outputs the first demand anti-skid target torque;

Calculate the torque distribution coefficient of the front and rear axles according to the first required anti-skid target torque and the limited total required torque of the front and rear axles;

Calculate the required torque of the rear axle according to the torque distribution coefficient of the front and rear axles and the total required torque of the front and rear axles, the rear axle of the motor outputs the required torque of the rear axle, and the front axle of the motor outputs the first required anti-skid target torque;

Limiting the rear axle demand torque according to the rear axle anti-skid target torque so that the motor rear axle outputs a second demand anti-skid target torque;

Calculate front and rear axle torque distribution coefficients according to the second required anti-skid target torque and the limited front and rear axle required torques;

The front axle required torque is calculated according to the front and rear axle torque distribution coefficient and the front and rear axle total required torque, the motor front axle outputs the front axle required torque, and the motor rear axle outputs the second required anti-skid target torque.

Optionally, according to the actual wheel speed, the wheel angle, the yaw rate of the vehicle, the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle, the calculation of the front and rear target axle speeds of the vehicle includes:

Calculate a reference vehicle speed according to the actual wheel speed, the wheel angle and the vehicle yaw rate;

Calculate the reference axle speeds of the front and rear axles according to the reference vehicle speed, the wheel angle and the vehicle yaw rate;

Calculate the road surface utilization adhesion coefficient of the front and rear axles according to the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle;

Determine the target slip rate of the front and rear axles according to the reference vehicle speed and the road surface utilization adhesion coefficient;

The target shaft speed is calculated from the target slip rate and the reference shaft speed.

Optionally, according to the actual wheel speed, the wheel angle and the vehicle yaw rate, in the calculation of the reference vehicle speed:

Normalize the actual wheel speed; the formula is as follows:

Among them, v1 is the left front wheel speed; v2 is the right front wheel speed; v3 is the left rear wheel speed; v4 is the right rear wheel speed; v10 is the normalized left front wheel speed; v20 is the normalized right front wheel speed ; v30 is the normalized left rear wheel speed; v40 is the normalized right rear wheel speed; L is the wheelbase of the vehicle, b is the wheel torque, δ is the wheel angle,

is the yaw rate;

The reference speed is:

vref=min(v10, _v20.v30.v40 )

Wherein, v _ref is the reference vehicle speed.

Optionally, according to the reference vehicle speed, the wheel angle and the vehicle yaw rate, in the calculation of the reference axle speeds of the front and rear axles:

The reference axis speed for the front axle is:

Wherein, w1 is the reference axle speed of the front axle; _vref is the reference vehicle speed;

is the yaw rate; L is the wheelbase of the vehicle; δ is the wheel angle;

The reference axis speed of the rear axle is:

w2= _vref

Wherein, w2 is the reference axle speed of the rear axle; v _ref is the reference vehicle speed.

Optionally, calculating the road surface utilization adhesion coefficient of the front and rear axles according to the lateral acceleration and the lateral acceleration;

The adhesion coefficient of the road surface is:

μ=a

Among them, a _x is the longitudinal acceleration; a _y is the lateral acceleration; a is the vehicle acceleration; μ is the road surface utilization adhesion coefficient.

Optionally, calculate the actual front and rear axle speeds of the vehicle according to the actual wheel speed:

ω10=(v1+v2)/2

ω20=(v3+v4)/2

Among them, v1 is the speed of the left front wheel; v2 is the speed of the right front wheel; v3 is the speed of the left rear wheel; v4 is the speed of the right rear wheel; ω10 is the actual axle speed of the front axle; ω20 is the actual axle speed of the rear axle.

Optionally, in determining the target slip ratio of the front and rear axles according to the reference vehicle speed and the road surface using the adhesion coefficient:

The front axle target slip rate is:

γ1=lookupTable1(v _ref , μ)

Wherein, μ is the adhesion coefficient of the road surface utilization; vref is the reference vehicle speed; _lookupTable1 is the simulation chart 1; γ1 is the target slip rate of the front axle;

γ2=lookupTabl+2(v _ref , μ)

Among them, μ is the adhesion coefficient of the road surface utilization; vref is the reference vehicle speed; _lookupTable2 is the simulation chart 2; γ2 is the target slip rate of the rear axle.

Optionally, in the calculation of the target shaft speed according to the target slip rate and the reference shaft speed:

ω _target1 =(1+γ1)·ω1

ω _target2 =(1+γ2)·ω2

Wherein, ω1 is the reference axis speed of the front axle; ω2 is the reference axis speed of the rear axle; γ1 is the target slip rate of the front axle; γ2 is the target slip rate of the rear axle; ω _target1 is the front axle ω _target2 is the target axle speed of the rear axle.

On the other hand, the embodiment of the present application also provides a dual-motor four-wheel drive electric vehicle, and the electric vehicle includes:

processor;

storage means for storing a plurality of programs,

When the program is executed by the processor, the processor implements the driving anti-skid control method of the electric vehicle as in the above-mentioned first aspect.

Description of drawings

1 is a flowchart of a driving anti-skid control method for an electric vehicle provided in Embodiment 1 of the present application;

FIG. 2 is a flowchart of another method for driving anti-skid control of an electric vehicle provided in Embodiment 1 of the present application;

FIG. 3 is a schematic structural diagram of a dual-motor four-wheel drive electric vehicle according to Embodiment 3 of the present application.

detailed description

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all the structures related to the present application.

Example 1

FIG. 1 is a flowchart of a driving anti-skid control method for an electric vehicle provided in Embodiment 1 of the present application. As shown in FIG. 1 , the method may include the following steps:

S110: Acquire the actual wheel speed, wheel angle, vehicle yaw rate, vehicle lateral acceleration and vehicle longitudinal acceleration of the wheel.

Among them, the actual wheel speed of the left front wheel, left rear wheel, right rear wheel and right front wheel of the car can be obtained by each wheel speed sensor; the wheel angle can be obtained by the car angle sensor; the car yaw rate can be obtained by the car yaw rate sensor . The lateral acceleration of the car can be obtained through the lateral acceleration sensor of the car; the longitudinal acceleration of the car can be obtained through the longitudinal acceleration sensor of the car.

S120: Calculate the front and rear target axle speeds of the vehicle according to the actual wheel speed, wheel angle, vehicle yaw rate, vehicle lateral acceleration and vehicle longitudinal acceleration.

In one embodiment, the actual vehicle speed of the vehicle can be calculated according to the actual wheel speed, the wheel angle and the vehicle yaw rate; the front and rear reference axis speeds of the vehicle can be calculated according to the actual vehicle speed, the wheel angle and the vehicle yaw rate; The vehicle's longitudinal acceleration calculates the vehicle's acceleration to calculate the road surface utilization adhesion coefficient; then calculates the vehicle's target slip rate according to the actual vehicle speed and road surface utilization adhesion coefficient; finally calculates the vehicle's front and rear targets through the vehicle's target slip rate and the vehicle's front and rear reference axis speeds axis speed.

S130. Calculate the actual front and rear axle speeds of the vehicle according to the actual wheel speeds.

Exemplarily, the actual axle speed of the front axle of the vehicle can be obtained by calculating the wheel speed of the left front wheel and the wheel speed of the left rear wheel; the actual axle speed of the rear axle of the automobile can be obtained by calculating the wheel speed of the right front wheel and the wheel speed of the right rear wheel. .

S140, according to the target front and rear axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle, calculate the anti-skid target torque output by the motor to control the axle speed deviation between the front and rear target axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle.

Wherein, when the speed of the front and rear target axles of the car is greater than the actual speed of the front and rear axles of the car, the traction controller of the car starts to drive the motor to perform anti-skid control; Target torque, control the motor to output the anti-skid target torque, under the anti-skid target torque, control the distribution of the vehicle's torque between the front and rear axles to make the vehicle's front and rear target axle speeds close to the car's actual front and rear axle speeds, so that the vehicle's slip rate is controlled at Near the target slip rate, so as to ensure good adhesion between the tire and the ground, so as to obtain good driving performance and handling stability. In the related art, in the driving anti-skid control technology, the braking torque of the driving wheel or the torque reduction control of the engine is controlled, which will affect the power output of the vehicle, and there are also poor starting driving stability and poor driving experience for the driver of the vehicle. And other issues.

Optionally, a modification is made on the basis of the above-mentioned embodiment. FIG. 2 is a flowchart of another method for driving anti-skid control of an electric vehicle provided in Embodiment 1 of the present application; as shown in FIG. 2 , the method may include:

S210. Calculate the reference vehicle speed according to the actual wheel speed, the wheel angle and the vehicle yaw rate.

Among them, according to the actual wheel speed, wheel angle and vehicle yaw rate, the calculation of the reference vehicle speed includes:

1) Normalize the actual wheel speed of each wheel at the center of the rear axle of the vehicle; the formula is as follows:

Among them, v1 is the left front wheel speed; v2 is the right front wheel speed; v3 is the left rear wheel speed; v4 is the right rear wheel speed; v10 is the normalized left front wheel speed; v20 is the normalized right front wheel speed ; v30 is the normalized left rear wheel speed; v40 is the normalized right rear wheel speed; L is the distance between the front and rear axles of the car, b is the wheel torque, δ is the wheel angle,

is the yaw angular velocity.

2) Select the minimum value of the normalized wheel speeds of each wheel as the reference speed:

vref=min(v10, _v20.v30.v40 )

Among them, _vref is the reference vehicle speed.

S220. Calculate the reference axle speeds of the front and rear axles according to the reference vehicle speed, the wheel angle, and the vehicle yaw rate.

Among them, according to the reference vehicle speed, wheel angle and vehicle yaw rate, when the vehicle is in the steering condition, the calculated reference axle speeds of the front and rear axles include:

1) Calculate the reference axle speed of the front axle of the vehicle as:

Among them, w1 is the reference axle speed of the front axle; _vref is the reference vehicle speed calculated in step 1; φ is the yaw rate; L is the wheelbase of the vehicle; δ is the wheel angle;

2) Calculate the reference axle speed of the rear axle of the vehicle as:

w2= _vref

Among them, w2 is the reference axle speed of the rear axle; v _ref is the reference vehicle speed.

S230: Calculate the road surface utilization adhesion coefficient of the front and rear axles according to the lateral acceleration and the longitudinal acceleration.

Among them, the road surface adhesion coefficient is an important parameter that affects the driving anti-skid control; its size mainly depends on factors such as the movement of the vehicle and the condition of the road surface. According to the situation of the vehicle movement, the calculation formula of the road adhesion coefficient is as follows:

μ=a

Among them, a _x is the lateral acceleration; a _y is the longitudinal acceleration; a is the vehicle acceleration; μ is the road surface utilization adhesion coefficient.

S240, determining the target slip rate of the front and rear axles according to the reference vehicle speed and the road surface adhesion coefficient;

Among them, the slip rate of the wheels will directly affect the stability of the vehicle. It can be understood that when the slip ratio of the wheel is larger in the process of driving the anti-skid control, the larger the proportion of the wheel slip component in the movement, the worse the stability of the vehicle. Therefore, the slip rate of the wheel is controlled near the target slip rate, which can ensure good adhesion between the tire and the ground, improve the stability of the vehicle, and also enable the vehicle to obtain good driving performance. The formula for calculating the target slip rate for the front and rear axles is:

1) Calculate the target slip rate of the front axle:

γ1=lookupTable1(v _ref , μ)

Among them, μ is the adhesion coefficient of road surface utilization; v _ref is the reference vehicle speed; lookupTable1 is the simulation chart 1; γ1 is the target slip rate of the front axle;

2) Calculate the target slip rate of the rear axle:

γ2=lookupTable2(v _ref , μ)

Among them, μ is the adhesion coefficient of road surface utilization; vref is the reference vehicle speed; _lookupTable2 is the simulation chart 2; γ2 is the target slip rate of the rear axle.

S250. Calculate the target shaft speed according to the target slip rate and the reference shaft speed.

Among them, the target shaft speed is calculated according to the target slip rate and the reference shaft speed, and the formula can be:

1) Calculate the target axis speed of the front axis as:

ω _target1 =(1+γ1)·ω1

Among them, ω1 is the reference axis speed of the front axle; γ1 is the target slip rate of the front axle; ω _target1 is the target axle speed of the front axle;

2) Calculate the target axis speed of the rear axis as:

ω _target2 =(1+γ2)·ω2

Among them, ω _target1 is the target axis speed of the front axle; ω2 is the reference axis speed of the rear axle; γ2 is the target slip rate of the rear axle;

S260. Calculate the actual front and rear axle speeds of the vehicle according to the actual wheel speed.

The calculation of the actual front and rear axle speeds of the vehicle according to the actual wheel speeds may include:

1) Calculate the actual axle speed of the front axle as:

ω10=(v1+v2)/2

Among them, v1 is the speed of the left front wheel; v2 is the speed of the right front wheel; ω10 is the actual axle speed of the front axle;

2) Calculate the actual axis speed of the rear axle as:

ω20=(v3+v4)/2

Among them, v3 is the left rear wheel speed; v4 is the right rear wheel speed; ω20 is the actual axle speed of the rear axle.

S270 , according to the target front and rear axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle, calculate the anti-skid target torque output by the motor to control the axle speed deviation between the front and rear target axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle.

Among them, the anti-skid target torque includes the front axle anti-skid target torque and the rear axle anti-skid target torque;

1) The calculation formula of the anti-skid target torque of the front axle is:

Wherein, K _P , K _l , and K _D are the control parameters of the controller; ω ₁₀ is the actual axle speed of the front axle; ω _target1 is the target axle speed of the front axle; T _target1 is the anti-skid target torque of the front axle;

2) The formula for calculating the anti-skid target torque of the rear axle is:

Wherein, K _P , K _l , and K _D are the control parameters of the controller; ω ₂₀ is the actual axle speed of the rear axle; ω _target2 is the target axle speed of the rear axle; T _target2 is the anti-skid target torque of the rear axle;

Exemplarily, when the actual axle speed ω ₁₀ of the front axle of the vehicle is greater than the target axle speed ω _target1 of the front axle of the vehicle, the vehicle traction controller starts to drive the anti-skid control of the front axle of the motor, the front axle of the motor outputs the anti-skid target torque T _target1 , and the front axle of the motor outputs the anti-skid target torque T target1 . Under the anti-skid target torque, the actual speed of the vehicle is controlled so that the slip rate of the vehicle is controlled near the target slip rate, so as to ensure good adhesion between the tire and the ground, so as to obtain good driving performance and handling stability.

When the actual axle speed ω ₂₀ of the rear axle of the vehicle is greater than the target axle speed ω _target2 of the rear axle of the vehicle, the vehicle traction controller starts to drive the anti-skid control of the rear axle of the motor, the rear axle of the motor outputs the anti-skid target torque T _target2 , and the rear axle of the motor is at the anti-skid target torque The actual speed of the vehicle is controlled so that the slip rate of the vehicle is controlled near the target slip rate, so as to ensure good adhesion between the tire and the ground, so as to obtain good driving performance and handling stability.

S280. Limit the front axle demand torque according to the front axle anti-skid target torque, so that the motor front axle outputs the first demand anti-skid target torque.

The torque required for the front axle is:

T _front =min(T _target1 ,T _front )

Among them, T _front is the front axle demand torque; T _target1 front axle anti-skid target torque;

In the actual vehicle driving process, the driver's front axle demand torque is greater than the front axle anti-skid target torque, and the driver's front axle demand torque is limited so that the motor front axle outputs the first anti-skid target torque T _target1 . Exemplarily, when the driver's front axle demand torque is 300N.m and the front axle anti-skid target torque is 200N.m, the front axle demand torque is limited so that the motor front axle outputs the first demand anti-skid target torque of 200N.m, so as to The front axle of the vehicle performs drive anti-skid control.

S290. Calculate the front and rear axle torque distribution coefficient according to the first required anti-skid target torque and the limited total front and rear axle required torques.

Among them, the torque distribution coefficient of the front and rear axles can be calculated as:

Among them, T _target1 is the output first demand anti-skid target torque of the front axle; T _rear is the demand torque of the rear axle; i is the torque distribution coefficient of the front axle; (1-i) is the torque distribution coefficient of the rear axle; the difference between T _target1 and T _rear and is the total required torque of the front and rear axles after the limitation.

S300: Calculate the required torque of the rear axle according to the torque distribution coefficient of the front and rear axles and the total required torque of the front and rear axles, the rear axle of the motor outputs the required torque of the rear axle, and the front axle of the motor outputs the first required anti-skid target torque.

Among them, the required torque of the rear axle is:

T _rear = i·T _drv

T _front =(1-i)·T _drv

Among them, T _drv is the total required torque of the front and rear axles, here refers to the total required torque of the front and rear axles of the driver; i is the torque distribution coefficient of the front axle; T _rear is the required torque of the rear axle; T _front is the required torque of the front axle;

What needs to be explained here is that when the traction controller of the vehicle starts to perform driving anti-skid control on the front axle of the motor, for example, when the driver's front axle demand torque is 300N.m, the rear axle demand torque is 200N.m, and the front and rear axles The total required torque is 500N.m; the anti-skid target torque of the front axle is 200N.m, the output torque of the front axle is limited to 200N.m, and the rear axle still outputs the required torque of 200N.m; Calculate the required torque of the rear axle according to the torque distribution coefficient of the front and rear axles and the total required torque of the front and rear axles; at this time, the torque distribution coefficient of the rear axle is 1/2, and the torque distribution coefficient of the front axle is 1/2. The corresponding calculation results in the required torque output by the rear axle. It is 250N.m, and the calculated output torque of the front axle and the rear axle is 250N.m; since the front axle anti-skid target torque is 200N.m, the front axle outputs the first anti-skid target torque of 200N.m, and the rear axle outputs the rear axle demand. Torque is 250N.m. In this way, the rear axle output demand torque of 250N.m is compared with the rear axle output demand torque 200N.m before the calculation of the torque distribution coefficient, the rear axle demand torque increases, and the torque of the front axle is transferred to the rear axle torque; It is understood that the first demand anti-skid target torque output from the current axle is 200N.m; the output torque of the rear axle is 250N.m, and then the torque distribution of the front and rear axles is carried out; the torque distribution of the rear axle continues to increase. The torque of the front axle is transferred to the required torque of the rear axle. On the basis of realizing the anti-skid control of the front axle of the vehicle, the solution also keeps the basic power output of the vehicle unchanged, which improves the driving experience.

Optionally, limiting the rear axle demand torque according to the rear axle anti-skid target torque so that the motor rear axle outputs the second required anti-skid target torque;

Among them, when the vehicle traction controller starts to drive the anti-skid control of the rear axle of the motor, it also re-calculates the torque distribution coefficient of the front and rear axles, and combines the total required torque of the front and rear axles of the driver to calculate the required torque of the front and rear axles. The torque is transferred to the required torque of the front axle, so that the power output of the whole vehicle is basically unchanged, and the driving experience is improved.

Embodiment 2

The driving anti-skid control device for an electric vehicle provided by the embodiments of the present application can execute the driving anti-skid control method for an electric vehicle provided by the above-mentioned embodiments of the present application, and has functional modules and beneficial effects corresponding to the execution method. The control device includes:

Vehicle information acquisition module: used to acquire the actual wheel speed, wheel angle, vehicle yaw rate, vehicle lateral acceleration and vehicle longitudinal acceleration;

Vehicle front and rear target axis speed calculation module: used to calculate the vehicle front and rear target axis speed according to the actual wheel speed, the wheel angle, the vehicle yaw rate, the vehicle lateral acceleration and the vehicle longitudinal acceleration;

The vehicle front and rear actual axle speed calculation module: used to calculate the actual front and rear axle speeds of the vehicle according to the actual wheel speed;

Anti-skid target torque output module: an axis used to calculate the motor output anti-skid target torque to control the target front and rear axle speeds of the car and the actual front and rear axle speeds of the car according to the target front and rear axle speeds of the car and the actual front and rear axle speeds of the car speed deviation.

Embodiment 3

FIG. 3 is a schematic structural diagram of a dual-motor four-wheel drive electric vehicle provided in Embodiment 3 of the application. As shown in FIG. 3 , the electric vehicle includes a processor 70, a memory 71, an input device 72 and an output device 73; The number of processors 70 may be one or more, and one processor 70 is taken as an example in FIG. 3 ; the processor 70, the memory 71, the input device 72 and the output device 73 in the electric vehicle may be connected by a bus or other means, as shown in FIG. 3 takes the connection through the bus as an example.

As a computer-readable storage medium, the memory 71 can be used to store software programs, computer-executable programs, and modules, such as program instructions corresponding to the driving anti-skid control method of the electric vehicle in the embodiment of the present application. The processor 70 executes various functional applications and data processing of the dual-motor four-wheel drive electric vehicle by running the software programs, instructions and modules stored in the memory 71, ie, realizes the above-mentioned driving anti-skid control method of the electric vehicle.

The memory 71 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal, and the like. In addition, the memory 71 may include high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid-state storage device. In some examples, memory 71 may include memory located remotely from processor 70, which may be connected to the electric vehicle via a network. Examples of such networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

The input device 72 may be used to receive input numerical or character information, and generate key signal input related to user settings and function control of the electric vehicle. The output device 73 may include a display device such as a display screen.

The driving anti-skid control method in the embodiment of the present application includes acquiring the actual wheel speed, wheel angle, vehicle yaw rate, vehicle lateral acceleration and vehicle longitudinal acceleration of the wheel; The swivel angular velocity, the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle are used to calculate the front and rear target axle speeds of the vehicle; the actual front and rear axle speeds of the vehicle are calculated according to the actual wheel speeds; The speed calculation motor outputs the anti-skid target torque to control the axle speed deviation between the front and rear target axle speeds of the vehicle and the actual axle speeds in the front and rear of the vehicle. The technical solution controls the driving of the front and rear axles respectively, and outputs the anti-skid target torque to coordinate and limit the motor torque of the front and rear axles, and distributes the torque of the front and rear axle motors, so that the power output of the whole vehicle remains unchanged, and the driving experience is improved. The invention solves the problem that in the driving anti-skid control technology in the related art, the braking torque of the driving wheel or the torque reduction control of the engine is used to prevent the excessive slip of the driving wheel during the starting acceleration process of the vehicle, which will affect the power output of the vehicle. There are problems such as poor starting driving stability and poor driving experience of the vehicle driver.

Claims

A driving anti-skid control method for an electric vehicle, comprising:

Get the actual wheel speed, wheel angle, vehicle yaw rate, vehicle lateral acceleration and vehicle longitudinal acceleration;

According to the actual wheel speed, the wheel angle, the yaw rate of the vehicle, the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle, calculate the front and rear target axle speeds of the vehicle;

Calculate the actual front and rear axle speeds of the vehicle according to the actual wheel speed;

According to the target front and rear axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle, the motor output anti-skid target torque is calculated to control the axle speed deviation between the front and rear target axle speeds of the vehicle and the actual front and rear axle speeds of the vehicle.
The driving anti-skid control method of an electric vehicle according to claim 1, wherein the anti-skid target torque includes a front-axle anti-skid target torque and a rear-axle anti-skid target torque; the method further comprises:

Limiting the front axle demand torque according to the front axle anti-skid target torque so that the motor front axle outputs the first demand anti-skid target torque;

Calculate the torque distribution coefficient of the front and rear axles according to the first required anti-skid target torque and the limited total required torque of the front and rear axles;

Calculate the required torque of the rear axle according to the torque distribution coefficient of the front and rear axles and the total required torque of the front and rear axles, the rear axle of the motor outputs the required torque of the rear axle, and the front axle of the motor outputs the first required anti-skid target torque;

Limiting the rear axle demand torque according to the rear axle anti-skid target torque so that the motor rear axle outputs a second demand anti-skid target torque;

Calculate front and rear axle torque distribution coefficients according to the second required anti-skid target torque and the limited front and rear axle required torques;

The front axle required torque is calculated according to the front and rear axle torque distribution coefficient and the front and rear axle total required torque, the motor front axle outputs the front axle required torque, and the motor rear axle outputs the second required anti-skid target torque.
The driving anti-skid control method of an electric vehicle according to claim 1, wherein the method is based on the actual wheel speed, the wheel angle, the yaw rate of the vehicle, the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle, Calculate the vehicle's front and rear target axle speeds, including:

Calculate a reference vehicle speed according to the actual wheel speed, the wheel angle and the vehicle yaw rate;

Calculate the reference axle speeds of the front and rear axles according to the reference vehicle speed, the wheel angle and the vehicle yaw rate;

Calculate the road surface utilization adhesion coefficient of the front and rear axles according to the lateral acceleration of the vehicle and the longitudinal acceleration of the vehicle;

Determine the target slip rate of the front and rear axles according to the reference vehicle speed and the road surface utilization adhesion coefficient;

The target shaft speed is calculated from the target slip rate and the reference shaft speed.
The driving anti-skid control method for an electric vehicle according to claim 3, wherein, according to the actual wheel speed, the wheel angle and the vehicle yaw rate, in calculating the reference vehicle speed:

Normalize the actual wheel speed; the formula is as follows:

Among them, v1 is the left front wheel speed; v2 is the right front wheel speed; v3 is the left rear wheel speed; v4 is the right rear wheel speed; v10 is the normalized left front wheel speed; v20 is the normalized right front wheel speed ; v30 is the normalized left rear wheel speed; v40 is the normalized right rear wheel speed; L is the wheelbase of the vehicle, b is the wheel torque, δ is the wheel angle,
is the yaw rate;

The reference speed is:

vref=min(v10, v20.v30.v40 )

Wherein, v ref is the reference vehicle speed.
The driving anti-skid control method of an electric vehicle according to claim 4, wherein, in calculating the reference axis speed of the front and rear axles according to the reference vehicle speed, the wheel angle and the vehicle yaw rate:

The reference axis speed for the front axle is:

Wherein, w1 is the reference axle speed of the front axle; vref is the reference vehicle speed;
is the yaw rate; L is the wheelbase of the vehicle; δ is the wheel angle;

The reference axis speed of the rear axle is:

w2= vref

Wherein, w2 is the reference axle speed of the rear axle; v ref is the reference vehicle speed.
The driving anti-skid control method of an electric vehicle according to claim 3, wherein the road surface utilization adhesion coefficient of the front and rear axles is calculated according to the lateral acceleration and the lateral acceleration;

The adhesion coefficient of the road surface is:

μ=a

Among them, a x is the longitudinal acceleration; a y is the lateral acceleration; a is the vehicle acceleration; μ is the road surface utilization adhesion coefficient.
The driving anti-skid control method of an electric vehicle according to claim 1, wherein, in calculating the actual front and rear axle speeds of the vehicle according to the actual wheel speed:

ω10=(v1+v2)/2

ω20=(v3+v4)/2

Among them, v1 is the speed of the left front wheel; v2 is the speed of the right front wheel; v3 is the speed of the left rear wheel; v4 is the speed of the right rear wheel; ω10 is the actual axle speed of the front axle; ω20 is the actual axle speed of the rear axle.
The driving anti-skid control method of an electric vehicle according to claim 3, wherein the target slip ratio of the front and rear axles is determined according to the reference vehicle speed and the road surface adhesion coefficient:

The front axle target slip rate is:

γ1=lookupTable1(v ref , μ)

Wherein, μ is the adhesion coefficient of the road surface utilization; vref is the reference vehicle speed; lookupTable1 is the simulation chart 1; γ1 is the target slip rate of the front axle;

γ2=lookupTable2(v ref , μ)

Among them, μ is the adhesion coefficient of the road surface utilization; vref is the reference vehicle speed; lookupTable2 is the simulation chart 2; γ2 is the target slip rate of the rear axle.
The driving anti-skid control method of an electric vehicle according to claim 3, wherein, in the calculation of the target shaft speed according to the target slip rate and the reference shaft speed:

ω target1 =(1+γ1)·ω1

ω target2 =(1+γ2)·ω2

Wherein, ω1 is the reference axis speed of the front axle; ω2 is the reference axis speed of the rear axle; γ1 is the target slip rate of the front axle; γ2 is the target slip rate of the rear axle; ω target1 is the front axle ω target2 is the target axle speed of the rear axle.
A dual-motor four-wheel drive electric vehicle, the electric vehicle comprises:

processor;

storage device for storing programs,

When the program is executed by the processor, the processor implements the driving anti-skid control method for an electric vehicle according to any one of claims 1-9.