CN117002478A - Control method, controller, system and vehicle for distributed driving electric automobile - Google Patents

Abstract

The invention provides a control method, a controller, a system and a vehicle for a distributed driving electric automobile, which comprise the following steps: determining the basic torque of each wheel according to the opening degree of an accelerator pedal and the fault level of the vehicle; determining an additional anti-skid torque and/or an additional yaw torque of the vehicle; adjusting each basic torque based on the additional anti-skid torque and/or the additional yaw torque, and outputting the required torque of each wheel; determining a driving control strategy according to the required torque of the wheels and the maximum output torque of each hub motor; thus, when the vehicle is integrated with the distributed driving system and the traditional chassis integrated control system, after the required torque of each wheel is determined, a corresponding control strategy can be determined based on the maximum output torque of each wheel hub motor, and if the maximum output torque is insufficient, the chassis integrated control system provides compensation; therefore, overall coordination of function control of the distributed driving system and the chassis integrated control system is realized, the control resource utilization rate is improved, and the whole vehicle control effect is ensured.

Description

Control method, controller, system and vehicle for distributed driving electric automobile

Technical Field

The application relates to the technical field of distributed driving whole vehicle control, in particular to a control method, a controller, a system and a vehicle of a distributed driving electric vehicle.

Background

With the continuous and deep research of electric automobile technology, the arrangement structure of a driving system of an electric automobile gradually develops from a centralized driving system with a single power source to a distributed driving system with multiple power sources.

However, when the distributed driving system and the traditional chassis integrated control system are integrated in the vehicle, the functions of the distributed driving system and the chassis integrated control system overlap, for example, the distributed driving system and the chassis integrated control system can realize longitudinal driving anti-skid and yaw stability control on the vehicle.

Aiming at the aim of improving the operability and the running stability of the vehicle, the function control of the distributed driving system and the chassis integrated control system cannot be coordinated in an overall way in the prior art, so that the control resource waste is caused, and the control effect of the whole vehicle is also influenced.

Disclosure of Invention

Aiming at the problems existing in the prior art, the embodiment of the application provides a control method, a controller, a system and a vehicle for a distributed driving electric automobile, which are used for solving or partially solving the technical problems that the prior art cannot comprehensively coordinate the function control of the distributed driving system and the chassis integrated control system, so that the control resource waste is caused, and the control effect of the whole automobile is affected.

In a first aspect of the present invention, a control method for a distributed driving electric vehicle is provided, and the method is applied to a power chassis domain controller, and includes:

acquiring an accelerator pedal opening and a vehicle fault level of a vehicle, and determining the basic torque of each wheel according to the accelerator pedal opening and the vehicle fault level;

determining an additional anti-skid torque of the wheels and/or an additional yaw torque of the vehicle;

adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels;

and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

In the above scheme, determining the base torque of each wheel according to the opening of the accelerator pedal and the fault level of the vehicle comprises:

determining a first total base torque of the vehicle according to the opening degree of the accelerator pedal;

adjusting the first total basic torque based on the fault level to obtain a corresponding total required torque;

the total required torque is distributed into a front axle basic torque and a rear axle basic torque according to a torque distribution mode;

and determining the average value of the front axle basic torques as the basic torques of the left front wheel and the right front wheel, and determining the average value of the rear axle basic torques as the basic torques of the left rear wheel and the right rear wheel.

In the above aspect, the determining the additional anti-skid torque of the vehicle includes:

determining, for any wheel, an actual slip rate of the wheel;

determining the actual slip rate of the wheels and the ideal slip rate of the wheels as input values of an additional anti-slip torque PID algorithm based on the PID algorithm of the additional anti-slip torque, and correspondingly obtaining a first output value; the first output value is the additional anti-skid torque.

In the above aspect, the determining the additional yaw torque of the vehicle includes:

when the steering wheel angle of the vehicle is not 0, acquiring the actual yaw rate of the vehicle;

determining an angular velocity difference between the actual yaw rate and an ideal yaw rate;

taking the angular velocity difference value as an input value of the PID control algorithm of the additional yaw torque based on the PID control algorithm of the additional yaw torque, and correspondingly obtaining a second output value; the second output value is an additional yaw torque of the vehicle.

In the above aspect, the adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting the required torque of each of the wheels, includes:

determining a torque adjustment for any wheel according to the additional anti-skid torque and/or the additional yaw torque;

Adjusting the basic torque according to the torque adjustment quantity to obtain the required torque of the corresponding wheel; wherein,

the required torque of the wheel is the sum of the base torque required by the wheel and the torque of the torque adjustment amount.

In the above-mentioned scheme, determining the driving control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor includes:

for any wheel, if the maximum output torque of the hub motor is greater than or equal to the required torque of the corresponding wheel, determining the control strategy as follows: the required torque of the wheel is provided by the in-wheel motor.

In the above-mentioned scheme, determining the driving control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor includes:

and if the maximum output torque of the hub motor is smaller than the required torque of the corresponding wheel, determining the control strategy as follows: controlling the hub motor to output maximum torque, and compensating target braking torque through a hydraulic loop; the target braking torque is a difference of the wheel demand torque minus a maximum output torque of the in-wheel motor.

In a second aspect of the present invention, there is provided a power chassis domain controller comprising:

The driving intention analysis module is used for acquiring the opening degree of an accelerator pedal of the vehicle;

the torque distribution module is used for determining the basic torque of each wheel according to the opening degree of the accelerator pedal;

a motor-driven anti-skid control module for determining an additional anti-skid torque for the wheel;

a motor torque vector control module for determining an additional yaw torque of the vehicle;

the driving arbitration module is used for adjusting each basic torque based on the additional anti-skid torque and/or the additional yaw torque and outputting the required torque of each wheel; and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

In a third aspect of the present invention, there is provided a control system for a distributed drive electric vehicle, the system comprising:

the vehicle control unit VCU is used for acquiring the vehicle fault grade;

the power chassis domain controller of the second aspect, configured to receive a failure level sent by the VCU, determine a base torque of each wheel based on an accelerator pedal opening of a vehicle and the vehicle failure level;

determining an additional anti-skid torque of the wheels and/or an additional yaw torque of the vehicle; adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels; and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

In a fourth aspect of the present invention, there is provided a vehicle including the control system of the distributed drive electric vehicle of the fourth aspect.

The invention provides a control method, a controller, a system and a vehicle for a distributed driving electric automobile, wherein the method comprises the following steps: acquiring an accelerator pedal opening and a vehicle fault level of a vehicle, and determining the basic torque of each wheel according to the accelerator pedal opening and the vehicle fault level; determining an additional anti-skid torque of the vehicle and/or an additional yaw torque of the vehicle; adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels; determining a driving control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor; thus, when the vehicle is integrated with the distributed driving system and the traditional chassis integrated control system, after the required torque of each wheel is determined, a corresponding control strategy can be determined based on the maximum output torque of each wheel hub motor, and if the maximum output torque is insufficient, the chassis integrated control system provides compensation; therefore, overall coordination of function control of the distributed driving system and the chassis integrated control system is realized, the utilization rate of the whole vehicle control resources is improved, and the whole vehicle control effect is ensured.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures.

In the drawings:

fig. 1 is a schematic diagram showing an overall structure of a control system of a distributed driving electric vehicle according to an embodiment of the present invention;

FIG. 2 illustrates a control logic diagram of a distributed drive electric vehicle according to one embodiment of the present invention;

FIG. 3 is a flow chart illustrating a control method of a distributed driving electric vehicle according to an embodiment of the present invention;

FIG. 4 illustrates a schematic diagram of a power chassis domain controller according to one embodiment of the invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In order to better understand the technical scheme of the application, a distributed driving system is introduced, wherein the distributed driving electric automobile drives respective wheels by two or more motors respectively, and the motors drive the wheels to move by controlling the torque and the rotating speed. The distributed driving system cancels the torque transmission of the middle differential, so the distributed driving system has the outstanding advantages of short driving transmission chain, high transmission efficiency, compact structure and the like.

The electric vehicle with the distributed driving has the characteristic of independent and controllable four wheels, and the pure electric vehicle can realize fine tire adhesion distribution by utilizing the characteristic of independent and controllable four wheels, so that the operability and the running stability of the vehicle are improved. The distributed driving system can also match the optimal efficiency range of the motor with the working condition of the vehicle, so that the driving efficiency and the energy utilization rate are improved.

However, when the distributed driving electric automobile runs on the road surface to approach to a unsteady state, the vehicle state can be effectively controlled through the distributed driving system and the chassis integrated control system, so that functions of the distributed driving system and the chassis integrated control system are overlapped.

In addition, the conventional chassis integrated control system generally improves the stability of the vehicle by reducing the torque of the engine or independently controlling the braking force applied to the wheels, and the control mode needs to reduce the vehicle speed at the cost of reducing the running capacity of the vehicle, and can bring obvious intervention feeling to the driver and generate driving interference to the driver.

Based on this, an embodiment of the present invention provides a control system for a distributed driving electric automobile, as shown in fig. 1, where the system includes: a whole vehicle controller (VCU, vehicle Control Unit), a power chassis domain controller (CDU, conversion & Distribution Unit), an integrated electronic brake control system (IBC, integrated brake control system), four in-wheel motors; wherein,

the vehicle control unit VCU is used for determining the vehicle fault level;

a power chassis domain Controller (CDU) for receiving the fault level sent by the VCU and determining the basic torque of each wheel based on the opening degree of an accelerator pedal of the vehicle and the fault level of the vehicle;

determining an additional anti-skid torque of the wheels and/or an additional yaw torque of the vehicle;

adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels; and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

And the IBC is used for controlling each hydraulic circuit to output corresponding target braking torque based on a control strategy and recovering braking energy according to the opening degree of a brake pedal.

Specifically, referring to FIG. 2, the power chassis domain controller CDU includes: the driving intention analysis module 21, the torque distribution module 22, the vehicle state determination module 23, the motor drive slip control module (ETC, electric Traction Control), the brake drive slip control module (BTC, brake Traction Control), the motor torque vector control module (TVC, torque Vector Control), the brake stability control module (VDC, vehicle Dynamics Control), the drive arbitration module 24, and the brake arbitration module 25.

The overall control logic of the control system of the distributed driving electric automobile is as follows:

generally, if the vehicle is in a good running state all the time, no slipping or instability occurs, and the CDU can directly drive according to the base torque of the wheels at this time, without adjusting the base torque of each wheel; wherein the base torque is positive at this time.

If the vehicle starts at full throttle on a road surface with a low adhesion coefficient (such as ice surface) or runs from a road surface with a high adhesion coefficient to a road surface with a low adhesion coefficient, a certain additional anti-skid torque needs to be provided at the moment to improve the adhesion of wheels and avoid the vehicle from skidding. Similarly, if the vehicle is unstable, some additional yaw torque is required to improve the stability of the vehicle. In this case, the base torque should be negative.

Based on this, after determining the base torque of each wheel, the base torque needs to be adjusted according to the additional anti-skid torque and/or the additional yaw torque, so as to obtain the required torque of each wheel.

And determining a vehicle control strategy according to the required torque of each wheel and the maximum output torque of the hub motor.

Specifically, first, the VCU monitors the fault status of various components of the vehicle (such as the IBC, the power chassis domain controller, and various hub motors) in real time, and determines the fault level of the vehicle according to the fault status.

Then, the driving intention analysis module 21 analyzes the driving intention to obtain a corresponding accelerator pedal opening, and transmits the accelerator pedal opening to the torque distribution module 22.

The torque distribution module 22 distributes the torque of each wheel according to the opening degree of the accelerator pedal and the fault level of the vehicle, and determines the basic torque of each wheel; and sends the base torque for each wheel to the drive arbitration module 24.

The vehicle state determination module 23 then obtains current travel parameters of the vehicle and determines a current vehicle state based on the current travel parameters. Wherein the current driving parameters may include: steering wheel angle, vehicle speed, wheel speed, etc.

The vehicle conditions may include a slip condition and a destabilizing condition, but the vehicle may have only a slip condition, may have only a destabilizing condition, or both a slip condition and a destabilizing condition at a time.

Thus, if the vehicle state determination module 23 determines that the vehicle is currently in a slip state, the ETC module determines additional anti-skid torque required for the wheels and sends the additional anti-skid torque to the drive arbitration module 24.

If it is determined that the vehicle is currently in a unstable state, the TVC module determines an additional yaw torque required by the wheels and sends the additional yaw torque to the drive arbitration module 24.

If the vehicle is currently in both a slip state and a unstable state, the ETC module sends additional anti-slip torque to the drive arbitration module 24, while the TVC module also sends additional yaw torque to the drive arbitration module 24.

After receiving the additional anti-skid torque and/or the additional yaw torque, the drive arbitration module 24 adjusts each base torque based on the additional anti-skid torque and/or the additional yaw torque and outputs a required torque for each wheel; and then, carrying out drive arbitration according to the required torque of each wheel and the maximum output torque of each wheel hub motor, and determining a corresponding control strategy.

For example, if the maximum output torque of the in-wheel motor is greater than or equal to the required torque of the corresponding wheel, the control strategy is: providing a required torque of the wheel by the hub motor; the drive arbitration module 24 sends the torque demand for each wheel to the corresponding in-wheel motor for execution.

For example, consider a vehicle in both skid and destabilized states, with the left front wheel being illustrated:

assuming that the base torque of the front left wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the required torque of the front left wheel is: 30-50-50= -70n.m.

That is, the left front wheel requires a brake torque of 70n.m to suppress slip and instability of the vehicle.

If the maximum output torque of the hub motor of the front left wheel is-80 n.m, the required torque of the front left wheel is provided by the hub motor.

However, when the maximum output torque of the in-wheel motor is smaller than the corresponding required torque and the vehicle is currently in a slip state, the maximum output torque is preferentially provided by the in-wheel motor, the remaining insufficient torque is determined as the first remaining braking torque, and the first remaining braking torque is sent to the braking arbitration module 25 by the BTC module.

If the maximum output torque of the in-wheel motor is smaller than the corresponding required torque and the vehicle is currently in a unstable state, the maximum output torque is preferentially provided by the in-wheel motor, the remaining insufficient torque is determined to be the second remaining braking torque, and the second remaining braking torque is sent to the braking arbitration module 25 by the VDC module.

If the vehicle is currently in both a slip state and an unstable state, the BTC module will send a first residual brake torque to the brake arbitration module 25, while the VDC module will also send a second residual brake torque to the brake arbitration module 25.

The brake arbitration module 25 determines a final target brake torque based on the first residual brake torque and/or the second residual brake torque.

It is understood that the target braking torque is the first remaining braking torque if the vehicle is currently in a slip state. And if the vehicle is in the unstable state currently, the target braking torque is the second residual braking torque. And if the vehicle is in a slipping state and is in a destabilizing state at the same time, the target braking torque is the sum of the first residual braking torque and the second residual braking torque. The sum of the first and second residual braking torques can also be understood as the difference of the required torque minus the maximum output torque of the in-wheel motor.

The corresponding control strategy is: and controlling the hub motor to output maximum torque, and compensating the target braking torque through a braking hydraulic circuit.

The brake hydraulic circuit is controlled by the IBC, that is, after the brake arbitration module 25 determines the corresponding target brake torque, a torque request is sent to the IBC, and after the IBC receives the torque request, the IBC provides a corresponding braking force for the wheels based on the target brake torque, so as to inhibit the slip and/or instability of the vehicle.

Continuing with the above example, assuming the vehicle is in both skid and unstable conditions, the left front wheel is illustrated as an example:

assuming that the base torque of the front left wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the required torque of the front left wheel is: 30-50-50= -70n.m.

That is, the left front wheel requires a brake torque of 70n.m to suppress slip and instability of the vehicle.

If the maximum output torque of the wheel hub motor of the left front wheel is-60 N.m and the target braking torque is-10 N.m, the CDU sends a torque request to the IBC, and the IBC controls the corresponding braking hydraulic pipeline to provide 10N.m target braking torque compensation.

In this way, the embodiment can carry out unified overall and distribution on the torque provided by the distributed driving system and the braking torque provided by the chassis integrated control system based on the vehicle state, solves the problem of functional overlapping of distributed driving and chassis integrated control, realizes unified control of the distributed driving system and the chassis integrated control system, improves the control resource utilization rate, and ensures the whole vehicle control effect.

Here, the power chassis domain controller CDU specific execution logic may refer to the following specific description of the power chassis domain controller side embodiment, so that the description is omitted here.

Based on the same inventive concept as the foregoing embodiment, the present embodiment further provides a control method of a distributed driving electric vehicle, which is applied to a power chassis domain controller CDU, as shown in fig. 3, and the method includes:

step S310, acquiring an accelerator pedal opening degree and a vehicle fault level of a vehicle, and determining the basic torque of each wheel according to the accelerator pedal opening degree and the vehicle fault level;

as described above, the VCU monitors the fault status of various components of the vehicle (such as IBC, power chassis domain controller, and various in-wheel motors) in real time, and determines the vehicle fault level based on the fault status. And transmits the vehicle fault level to the CDU.

For example, if all components inside the vehicle are fault-free, the vehicle fault class is 0; if the parts in the vehicle have 1-level faults and the fault level of all the parts does not exceed 1 level, the vehicle fault level is 1; if the parts in the vehicle have 2-level faults and the fault level of all the parts does not exceed 21-level, the vehicle fault level is 2; if there are components within the vehicle that fail at level 3, the vehicle failure level is level 3.

The CDU can collect the opening degree of the accelerator pedal of the vehicle in real time, receive the fault grade of the vehicle sent by the VCU, and determine the basic torque of each wheel according to the opening degree of the accelerator pedal and the fault grade of the vehicle.

In one embodiment, determining the base torque of each wheel based on the accelerator pedal opening and the vehicle failure level includes:

determining a first total base torque of the vehicle according to the opening degree of an accelerator pedal;

adjusting the first total basic torque based on the fault level to obtain a corresponding total required torque;

the total required torque is distributed into a front axle basic torque and a rear axle basic torque according to a torque distribution mode;

the average value of the front axle base torques is determined as the base torques of the left and right front wheels, and the average value of the rear axle base torques is determined as the base torques of the left and right rear wheels.

Specifically, a first total base torque expected by the vehicle is calculated according to the opening degree of an accelerator pedal and the vehicle state information. Wherein the vehicle state information includes: maximum output current I allowed by system _A Current I corresponding to current rotation speed of each hub motor and peak torque of each hub motor _a 。

Firstly, aiming at each hub motor, according to the current rotating speed, inquiring a motor rotating speed-moment external characteristic table to obtain a corresponding table-look-up maximum torque T _tmaxi (i=1, 2,3, 4), i being the number of the in-wheel motor. And further can determine the total torque T of the lookup table output of the system _outmax The method comprises the following steps:

T _outmax ＝T _tmax1 +T _tmax2 +T _tmax3 +T _tmax4 the method comprises the steps of carrying out a first treatment on the surface of the Wherein,

T _tmax1 Maximum torque, T, of the table look-up for the 1 st in-wheel motor _tmax2 Maximum torque, T, of the table look-up for the 2 nd in-wheel motor _tmax3 Maximum torque, T, of the table look-up for the 3 rd hub motor _tmax4 The maximum torque is looked up for the 4 th in-wheel motor.

Then judgeWhether or not is greater than 1, if yes>1 or more, determining that:

T _outmax ′＝T _outmax the method comprises the steps of carrying out a first treatment on the surface of the Wherein T is _outmax ' is the maximum output torque allowed by the system.

If it is determined thatLess than 1, then determine +.>

Can be according to formula T _outmax ″＝min(T _outmax ,T _outmax ') determining the final torque T _outmax ″；

Finally according to formula T _out ＝T _outmax Determining a first total base torque T }' Accopedal _out The method comprises the steps of carrying out a first treatment on the surface of the Wherein Accpedal is the accelerator pedal opening.

However, if the vehicle fails, the first total base torque needs to be adjusted according to the corresponding failure level. In practical application, the fault level and the torque adjustment coefficient have a corresponding relationship.

The vehicle failure level includes 4 stages (0 to 3 stages), and the torque adjustment coefficient includes 4 stages, 100%, 10%, and 0%, respectively.

For example, when the fault level is 0, the system operates normally, and the first total basic torque does not need to be adjusted; when the fault level is 1, the system gives an alarm, but the first total basic torque still operates normally without adjustment; when the fault level is 2, the first total basic torque is reduced to 0.1 times of the normal torque; when the system failure level is 3, the system does not output torque, and the torque is 0.

For example, assuming that the first total base torque is 1000n.m, the fault level is 2, and the corresponding torque adjustment coefficient is 10% (0.1), the total required torque obtained after the adjustment of the first total base torque is:

1000*10％＝100N.m。

after the total required torque is determined, the front and rear axle torque distribution proportion is determined by adopting a torque distribution mode proportional to the axle load based on the axle loads of the front and rear axles of the whole vehicle, and then the front axle torque and the rear axle torque are determined based on the front and rear axle torque distribution proportion.

For example, if the overall front-to-rear axle load ratio is 4:6, then the front-to-rear axle torque split ratio is also 4:6.

And determining the average value of the front axle base torques as the base torques of the left front wheel and the right front wheel, and determining the average value of the rear axle base torques as the base torques of the left rear wheel and the right rear wheel.

For example, assume a total demand torque of 800n.m, a front-to-rear axle torque split ratio of 4:6, then the front axle torque is 320n.m, the rear axle torque is 480n.m, the base torques of the left and right front wheels are 160n.m, respectively, and the base torques of the left and right rear wheels are 240n.m.

Step S311, determining an additional anti-skid torque of the wheels and/or an additional yaw torque of the vehicle;

as described above, if the vehicle is in a good running state all the time, no slip or instability occurs, and the CDU can directly drive according to the base torque of the wheels at this time, without adjusting the base torque of each wheel. At this time, slip and instability do not need to be suppressed, and therefore the base torque is a positive torque.

However, if the vehicle is running on a road surface with a low adhesion coefficient (such as ice surface) or running from a road surface with a high adhesion coefficient to a road surface with a low adhesion coefficient, a certain additional anti-slip torque needs to be provided at this time to improve the adhesion of the wheels and avoid the vehicle slipping.

Similarly, if the vehicle is unstable, some additional yaw torque is required to improve the stability of the vehicle.

The present embodiment therefore also requires determining additional anti-skid torque for the wheels and/or additional yaw torque for the vehicle.

In one embodiment, determining additional anti-skid torque for a vehicle includes:

determining an actual slip rate of the wheel for any of the wheels;

determining the actual slip rate of the wheels and the ideal slip rate of the wheels as input values of the PID algorithm of the additional anti-slip torque based on the PID algorithm of the additional anti-slip torque, and correspondingly obtaining a first output value; the first output value is the additional anti-slip torque.

Specifically, the actual slip rate S of each wheel may be determined according to equation (1) _x ：

In the formula (1), x is a wheel number, r is a wheel rolling radius, ω is a wheel rotation speed, and v is a current vehicle speed of the vehicle.

Then, the actual slip ratio of the wheels and the ideal slip ratio of the wheels are determined as input values of an additional anti-slip torque PID algorithm, and a first output value is correspondingly obtained, wherein the first output value is the additional anti-slip torque T. The PID algorithm of the additional anti-slip torque is shown in a formula (2):

In the formula (2), K _p 、K _i And K _d The scaling factor is determined based on empirical values and actual conditions of the vehicle, and is not limited herein. e (t) is the actual slip ratio of the wheel and the ideal slip ratio of the wheel.

In one embodiment, determining an additional yaw torque of the vehicle includes:

when the steering wheel angle of the vehicle is not 0, acquiring the actual yaw rate of the vehicle;

determining an angular velocity difference between the actual yaw rate and the ideal yaw rate;

based on a PID control algorithm of the additional yaw torque, taking the angular velocity difference value as an input value of the PID control algorithm of the additional yaw torque, and correspondingly obtaining a second output value; the second output value is an additional yaw torque of the vehicle.

Specifically, when the steering wheel angle is not 0, the ideal yaw rate of the vehicle may be determined using the two-degree-of-freedom vehicle reference model, the actual yaw rate of the vehicle may be determined using the gyroscope, and then the difference of the ideal yaw rate minus the actual yaw rate may be determined to obtain the corresponding angular velocity difference.

The angular velocity difference is taken as an input value of an additional yaw torque PID control algorithm, and the output value is taken as an additional yaw torque delta M required for inhibiting the instability of the vehicle _z . It should be noted that the accessory yaw torque of each wheel may be different, and the additional yaw torque of each wheel may be determined as follows:

since the additional yaw torque is achieved by left-right side differential torque adjustment with the longitudinal torque maintained, assuming that the left and right front wheels have diameters d1 and the left and right rear wheels have diameters d2, then:

front wheel torque adjustment amount Δf _f ：

Rear wheel torque adjustment amount Δf _r ：

The additional yaw torque of each wheel is as follows:

the additional yaw torque for the left front wheel is: - ΔF _f *R _FL The method comprises the steps of carrying out a first treatment on the surface of the The additional yaw torque for the right front wheel is: ΔF (delta F) _f *R _FR The method comprises the steps of carrying out a first treatment on the surface of the The additional yaw torque of the rear left wheel is- ΔF _r *R _RL The method comprises the steps of carrying out a first treatment on the surface of the The additional yaw torque of the right rear wheel is Δf _r *R _RR The method comprises the steps of carrying out a first treatment on the surface of the Wherein,

R _FL for the radius of the left front wheel, R _FR Radius of right front wheel, R _RL For the radius of the left rear wheel, R _RR Is the radius of the right rear wheel.

The additional yaw torque PID control algorithm can refer to the principle of the additional anti-slip torque PID algorithm, except that the additional yaw torque PID control algorithm is different from the input value of the additional anti-slip torque PID algorithm, and the proportionality coefficient is also different.

Step S312 of adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels;

After the additional anti-skid torque and the additional yaw torque of each wheel are determined, the base torque is adjusted based on the additional anti-skid torque and/or the additional yaw torque, and the required torque of each wheel is output.

In one embodiment, adjusting each base torque based on the additional anti-skid torque and/or the additional yaw torque and outputting a demand torque for each wheel includes:

determining a torque adjustment amount according to the additional anti-skid torque and/or the additional yaw torque for any wheel;

adjusting the basic torque according to the torque adjustment quantity to obtain the required torque of the corresponding wheel; wherein,

the required torque of the wheel is the sum of the base torque of the wheel and the torque of the torque adjustment amount.

As described above, the vehicle state may include a slip state and a destabilized state, but the vehicle may have only a slip condition, may have only a destabilized condition, or both the slip condition and the destabilized condition at a time.

For example, if the vehicle is currently in a skid state and in a unstable state, the left front wheel is taken as an example:

assuming that the base torque of the left front wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the torque adjustment amount is- (50n.m+50n.m) = -100n.m.

The required torque of the left front wheel is: 30-100= -70n.m.

The required torque for all wheels can be determined in the same way.

Step S313, determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

Since the maximum output torque of the in-wheel motor is limited, it is necessary to determine a control strategy based on the required torque of each wheel and the maximum output torque of each in-wheel motor.

In one embodiment, the drive control strategy is determined by the required torque of each wheel and the maximum output torque of each in-wheel motor, comprising:

for any wheel, if the maximum output torque of the hub motor is greater than or equal to the required torque of the corresponding wheel, determining the control strategy as follows: providing a required torque of the wheel by the hub motor;

if the maximum output torque of the hub motor is smaller than the required torque of the corresponding wheel, determining a control strategy as follows: controlling the hub motor to output maximum torque, and compensating target braking torque through a hydraulic loop; the target braking torque is the difference of the wheel demand torque minus the maximum output torque of the in-wheel motor.

For example, consider a vehicle in both skid and destabilized states, with the left front wheel being illustrated:

Assuming that the base torque of the front left wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the required torque of the front left wheel is: 30-50-50= -70n.m.

That is, the left front wheel requires a brake torque of 70n.m to suppress slip and instability of the vehicle.

If the maximum output torque of the hub motor of the front left wheel is 80n.m, the required torque of the front left wheel is provided by the hub motor.

If the maximum output torque of the hub motor is smaller than the corresponding required torque and the vehicle is in a slipping state currently, the maximum output torque is preferentially provided by the hub motor, and the residual insufficient torque is determined as the first residual braking torque.

If the maximum output torque of the hub motor is smaller than the corresponding required torque and the vehicle is in a unstable state currently, the maximum output torque is preferentially provided by the hub motor, and the residual insufficient torque is determined to be the second residual braking torque.

If the vehicle is currently in both a slip state and an unstable state, the CDU determines a final target brake torque based on the first and/or second residual brake torques.

It is understood that the target braking torque is the first remaining braking torque if the vehicle is currently in a slip state. And if the vehicle is in the unstable state currently, the target braking torque is the second residual braking torque. If the vehicle is in a slipping state and in an unstable state at the same time, the target braking torque is the sum of the first residual braking torque and the second residual braking torque; the sum of the first and second residual braking torques can also be understood as the difference of the required torque minus the maximum output torque of the in-wheel motor.

The corresponding control strategy is: and controlling the hub motor to output maximum torque, and compensating the target braking torque through a braking hydraulic circuit.

The brake hydraulic circuit is controlled by the IBC, namely, after the CDU determines the corresponding target brake torque, a torque request is sent to the IBC, and after the IBC receives the torque request, the IBC provides corresponding braking force for the wheels based on the target brake torque so as to inhibit slipping and/or instability of the vehicle.

Continuing with the above example, assuming the vehicle is in both skid and unstable conditions, the left front wheel is illustrated as an example:

assuming that the base torque of the front left wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the required torque of the front left wheel is: 30-50-50= -70n.m.

That is, the left front wheel requires a brake torque of 70n.m to suppress slip and instability of the vehicle.

If the maximum output torque of the wheel hub motor of the left front wheel is-60 N.m and the target braking torque is-10 N.m, the CDU sends a torque request to the IBC, and the IBC controls the corresponding braking hydraulic pipeline to provide 10N.m target braking torque compensation.

Therefore, the maximum output torque provided by the distributed driving system and the braking torque provided by the chassis integrated control system can be uniformly and comprehensively distributed based on the vehicle state, the problem of functional overlapping of the distributed driving and the chassis integrated control is solved, the uniform control of the distributed driving system and the chassis integrated control system is realized, and the control resource utilization rate is improved. And when the vehicle is in a unstable state, the instability is restrained without reducing the torque of the engine, so that the limit over-bending speed of the vehicle is improved, and the operability and the running stability of the vehicle are improved.

Based on the same inventive concept as the previous embodiments, this embodiment also provides a power domain chassis controller, as shown in fig. 4, the power domain chassis controller CDU includes:

a driving intention analysis module 21 for acquiring an accelerator pedal opening of the vehicle;

a torque distribution module 22 for determining a base torque of each wheel according to the accelerator pedal opening;

a motor-driven anti-skid control module ETC for determining an additional anti-skid torque for the wheel;

a motor torque vector control module TVC for determining an additional yaw torque of the vehicle;

a drive arbitration module 24 for adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels; and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

With continued reference to fig. 4, the power domain chassis controller CDU further includes: a vehicle state determination module 23, a brake drive slip control module BTC, a brake stability control module VDC, and a brake arbitration module 25;

specifically, first, the VCU monitors the fault status of various components of the vehicle (such as the IBC, the power chassis domain controller, and various hub motors) in real time, and determines the fault level of the vehicle according to the fault status.

Then, the driving intention analysis module 21 analyzes the driving intention to obtain a corresponding accelerator pedal opening, and transmits the accelerator pedal opening to the torque distribution module 22.

The torque distribution module 22 distributes the torque of each wheel according to the opening degree of the accelerator pedal and the fault level of the vehicle, and determines the basic torque of each wheel; and sends the base torque for each wheel to the drive arbitration module 24.

The vehicle state determination module 23 then obtains current travel parameters of the vehicle and determines a current vehicle state based on the current travel parameters. Wherein the current driving parameters may include: steering wheel angle, vehicle speed, wheel speed, etc.

The vehicle conditions may include a slip condition and a destabilizing condition, but the vehicle may have only a slip condition, may have only a destabilizing condition, or both a slip condition and a destabilizing condition at a time.

Thus, if the vehicle state determination module 23 determines that the vehicle is currently in a slip state, the ETC module determines additional anti-skid torque required for the wheels and sends the additional anti-skid torque to the drive arbitration module 24.

If it is determined that the vehicle is currently in a unstable state, the TVC module determines an additional yaw torque required by the wheels and sends the additional yaw torque to the drive arbitration module 24.

If the vehicle is currently in both a slip state and a unstable state, the ETC module sends additional anti-slip torque to the drive arbitration module 24, while the TVC module also sends additional yaw torque to the drive arbitration module 24.

After receiving the additional anti-skid torque and/or the additional yaw torque, the drive arbitration module 24 adjusts each base torque based on the additional anti-skid torque and/or the additional yaw torque and outputs a required torque for each wheel; and then, carrying out drive arbitration according to the required torque of each wheel and the maximum output torque of each wheel hub motor, and determining a corresponding control strategy.

For example, if the maximum output torque of the in-wheel motor is greater than or equal to the required torque of the corresponding wheel, the control strategy is: providing a required torque of the wheel by the hub motor; the drive arbitration module 24 sends the torque demand for each wheel to the corresponding in-wheel motor for execution.

For example, consider a vehicle in both skid and destabilized states, with the left front wheel being illustrated:

assuming that the base torque of the front left wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the required torque of the front left wheel is: 30-50-50= -70n.m.

That is, the left front wheel requires a brake torque of 70n.m to suppress slip and instability of the vehicle.

If the maximum output torque of the hub motor of the front left wheel is 80n.m, the required torque of the front left wheel is provided by the hub motor.

However, when the maximum output torque of the in-wheel motor is smaller than the corresponding required torque and the vehicle is currently in a slip state, the maximum output torque is preferentially provided by the in-wheel motor, the remaining insufficient torque is determined as the first remaining braking torque, and the first remaining braking torque is sent to the braking arbitration module 25 by the BTC module.

If the maximum output torque of the in-wheel motor is smaller than the corresponding required torque and the vehicle is currently in a unstable state, the maximum output torque is preferentially provided by the in-wheel motor, the remaining insufficient torque is determined to be the second remaining braking torque, and the second remaining braking torque is sent to the braking arbitration module 25 by the VDC module.

If the vehicle is currently in both a slip state and an unstable state, the BTC module will send a first residual brake torque to the brake arbitration module 25, while the VDC module will also send a second residual brake torque to the brake arbitration module 25.

The brake arbitration module 25 determines a final target brake torque based on the first residual brake torque and/or the second residual brake torque.

It is understood that the target braking torque is the first remaining braking torque if the vehicle is currently in a slip state.

And if the vehicle is in the unstable state currently, the target braking torque is the second residual braking torque.

And if the vehicle is in a slipping state and is in a destabilizing state at the same time, the target braking torque is the sum of the first residual braking torque and the second residual braking torque. In this state, the sum of the first and second remaining braking torques can also be understood as the difference of the required torque minus the maximum output torque of the in-wheel motor.

The corresponding control strategy is: and controlling the hub motor to output maximum torque, and compensating the target braking torque through a braking hydraulic circuit.

The brake hydraulic circuit is controlled by the IBC, that is, after the brake arbitration module 25 determines the corresponding target brake torque, a torque request is sent to the IBC, and after the IBC receives the torque request, the IBC provides a corresponding braking force for the wheels based on the target brake torque, so as to inhibit the slip and/or instability of the vehicle.

Continuing with the above example, assuming the vehicle is in both skid and unstable conditions, the left front wheel is illustrated as an example:

assuming that the base torque of the front left wheel is 30n.m, the additional anti-skid torque is-50 n.m, and the additional yaw torque is-50 n.m, the required torque of the front left wheel is: 30-50-50= -70n.m.

That is, the left front wheel requires a brake torque of 70n.m to suppress slip and instability of the vehicle.

If the maximum output torque of the wheel hub motor of the front left wheel is-60 n.m and the target brake torque is-10 n.m, the brake arbitration module 25 sends a torque request to the IBC, which controls the corresponding brake hydraulic line to provide the target brake torque compensation of 10 n.m.

Because the power chassis domain controller described in the embodiments of the present invention is a controller used for implementing the control method of the distributed driving electric vehicle in the embodiments of the present invention, based on the method described in the embodiments of the present invention, a person skilled in the art can understand the specific structure and deformation of the controller, and therefore, the description thereof is omitted herein. All controllers used in the method of the embodiment of the invention belong to the scope of the invention to be protected.

Based on the same inventive concept as the foregoing embodiments, the present invention further provides a vehicle, which includes the above-mentioned control system and power chassis domain controller of the distributed driving electric vehicle, and the control system and power chassis domain controller of the distributed driving electric vehicle may refer to the corresponding descriptions above, so that the description is omitted herein.

The control method, the controller, the system and the vehicle for the distributed driving electric vehicle have the advantages that:

the invention provides a control method, a controller, a system and a vehicle for a distributed driving electric automobile, wherein the method comprises the following steps: acquiring an accelerator pedal opening and a vehicle fault level of a vehicle, and determining the basic torque of each wheel according to the accelerator pedal opening and the vehicle fault level; determining an additional anti-skid torque for the vehicle; determining an additional yaw torque of the vehicle; adjusting each of the base torques based on the additional anti-skid torque and the additional yaw torque, and outputting a required torque of each of the wheels; determining a driving control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor; thus, when the vehicle is integrated with the distributed driving system and the traditional chassis integrated control system, after the required torque of each wheel is determined, a corresponding control strategy can be determined based on the maximum output torque of each wheel hub motor, and if the maximum output torque is insufficient, the chassis integrated control system provides compensation; therefore, overall coordination of function control of the distributed driving system and the chassis integrated control system is realized, the utilization rate of the whole vehicle control resources is improved, and the whole vehicle control effect is ensured.

It can be seen that the invention can cover the torque requirement of the whole scene (normal running state, slipping state and unsteady state) of the whole vehicle by analyzing the intention of the driver, distributing the torque, uniformly driving the anti-slip control and uniformly swaying control. The problem of functional overlapping of distributed driving and chassis integrated control is solved, unified control of a distributed driving system and a chassis unified integrated control system is realized, and the complexity of an algorithm is optimized; the stability boundary of the carrying distributed driving automobile is expanded, and in addition, when the automobile is in a unstable state, the instability is not required to be restrained in a mode of reducing the torque of the engine, so that the limit over-bending speed of the automobile is improved, and the operability and the running stability of the automobile are improved.

The above description is not intended to limit the scope of the invention, but is intended to cover any modifications, equivalents, and improvements within the spirit and principles of the invention.

Claims (10)

1. A control method for a distributed driving electric vehicle, which is applied to a power chassis domain controller, the method comprising:

acquiring an accelerator pedal opening and a vehicle fault level of a vehicle, and determining the basic torque of each wheel according to the accelerator pedal opening and the vehicle fault level;

Determining an additional anti-skid torque of the wheels and/or an additional yaw torque of the vehicle;

adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels;

and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

2. The method of claim 1, wherein determining the base torque for each wheel based on the accelerator pedal opening and the vehicle fault level comprises:

determining a first total base torque of the vehicle according to the opening degree of the accelerator pedal;

adjusting the first total basic torque based on the fault level to obtain a corresponding total required torque;

the total required torque is distributed into a front axle basic torque and a rear axle basic torque according to a torque distribution mode;

and determining the average value of the front axle basic torques as the basic torques of the left front wheel and the right front wheel, and determining the average value of the rear axle basic torques as the basic torques of the left rear wheel and the right rear wheel.

3. The method of claim 1, wherein the determining additional anti-skid torque for the vehicle comprises:

Determining, for any wheel, an actual slip rate of the wheel;

determining the actual slip rate of the wheels and the ideal slip rate of the wheels as input values of an additional anti-slip torque PID algorithm based on the PID algorithm of the additional anti-slip torque, and correspondingly obtaining a first output value; the first output value is the additional anti-skid torque.

4. The method of claim 1, wherein the determining the additional yaw torque of the vehicle comprises:

when the steering wheel angle of the vehicle is not 0, acquiring the actual yaw rate of the vehicle;

determining an angular velocity difference between the actual yaw rate and an ideal yaw rate;

taking the angular velocity difference value as an input value of the PID control algorithm of the additional yaw torque based on the PID control algorithm of the additional yaw torque, and correspondingly obtaining a second output value; the second output value is an additional yaw torque of the vehicle.

5. The method of claim 1, wherein said adjusting each of said base torques based on said additional anti-skid torque and/or said additional yaw torque and outputting a requested torque for each of said wheels comprises:

determining a torque adjustment for any wheel according to the additional anti-skid torque and/or the additional yaw torque;

Adjusting the basic torque according to the torque adjustment quantity to obtain the required torque of the corresponding wheel; wherein,

the required torque of the wheel is the sum of the base torque required by the wheel and the torque of the torque adjustment amount.

6. The method of claim 1, wherein determining a drive control strategy based on the required torque of each of the wheels and the maximum output torque of each of the in-wheel motors comprises:

for any wheel, if the maximum output torque of the hub motor is greater than or equal to the required torque of the corresponding wheel, determining the control strategy as follows: the required torque of the wheel is provided by the in-wheel motor.

7. The method of claim 1, wherein determining a drive control strategy based on the required torque of each of the wheels and the maximum output torque of each of the in-wheel motors comprises:

and if the maximum output torque of the hub motor is smaller than the required torque of the corresponding wheel, determining the control strategy as follows: controlling the hub motor to output maximum torque, and compensating target braking torque through a hydraulic loop; the target braking torque is a difference of the wheel demand torque minus a maximum output torque of the in-wheel motor.

8. A power chassis domain controller, the power chassis domain controller comprising:

the driving intention analysis module is used for acquiring the opening degree of an accelerator pedal of the vehicle;

the torque distribution module is used for determining the basic torque of each wheel according to the opening degree of the accelerator pedal;

a motor-driven anti-skid control module for determining an additional anti-skid torque for the wheel;

a motor torque vector control module for determining an additional yaw torque of the vehicle;

the driving arbitration module is used for adjusting each basic torque based on the additional anti-skid torque and/or the additional yaw torque and outputting the required torque of each wheel; and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

9. A control system for a distributed drive electric vehicle, the system comprising:

the vehicle control unit VCU is used for acquiring the vehicle fault grade;

the power chassis domain controller of claim 8, for receiving a failure level sent by the VCU, determining a base torque for each wheel based on an accelerator pedal opening of a vehicle and the vehicle failure level;

Determining an additional anti-skid torque of the wheels and/or an additional yaw torque of the vehicle; adjusting each of the base torques based on the additional anti-skid torque and/or the additional yaw torque, and outputting a required torque for each of the wheels; and determining a control strategy according to the required torque of each wheel and the maximum output torque of each wheel hub motor.

10. A vehicle comprising the control system of the distributed drive electric vehicle of claim 9.