Acceleration Slip Regulation And Torque Distribution Coordination Control For Distributed Drive Electric Vehicle

With the increasing energy shortage and environmental pollution,the development of new energy vehicles can improve the environment and energy structure.The pure electric vehicle has the advantages of zero emission during driving,simple structure and low noise.Besides the advantages of pure electric vehicle,the distributed drive electric vehicle has the characteristics of accurate control and rapid response in dynamics control.How to improve the dynamic performance and stability of the distributed drive electric vehicle has become the main research direction.This paper takes the distributed drive electric vehicle as the research object,takes the acceleration slip regulation and torque coordinated control as entry point,and makes a more in-depth study on the wheel slip ratio control,road identification and torque coordinated control of the vehicle.The main works are as follows:According to the real vehicle parameters,the structural parameters and drive system of traditional vehicle model in CarSim are modified,the input and output interfaces are configured,and combined with the driving motor and driver model established based on MATLAB/Simulink,then the distributed driving electric vehicle model is established.The simulation experiments of straight uniform acceleration and step input of steering wheel angle are carried out to verify the accuracy and effectiveness of the established model.In view of the wheel slip phenomenon of the distributed drive electric vehicle in the driving acceleration condition,an acceleration slip regulation robust controller based on sliding mode control is established,and the simulation experiment is carried out.Simulation results show that the chattering phenomenon of the acceleration slip regulation robust controller is obvious.In order to reduce the chattering phenomenon,an acceleration slip regulation controller based on new sliding surface is proposed,and the acceleration simulation on joint road is carried out.The simulation results show that the acceleration slip regulation controller based on the new sliding surface can reduce the chattering phenomenon of slip ratio sliding mode control,but it needs further optimization.The dynamics of single wheel is analyzed,and a road identification algorithm is designed based on Burckhardt tire model to identify the current driving road conditions,to improve the self-adaptive of acceleration slip regulation for distributed drive electric vehicle.The effectiveness of the road identification algorithm is verified by the acceleration on low,medium and high friction coefficient road.In order to reduce the chattering of wheel slip ratio at low speed acceleration stage,the control variable is redesigned,and the integral sliding mode controller based on the wheel speed is designed,which is combined with the road identification algorithm,so the wheel slip ratio can be adjusted according to the optimal slip ratio of the current driving road.The simulation experiments of driving acceleration of single road,docking road and split road are carried out.The simulation results show that the slip ratio adaptive controller based on wheel speed can maintain the wheel slip ratio near the optimal slip ratio,and the chattering of wheel slip ratio and motor torque is small.The torque coordinated control strategy for the distributed drive electric vehicle is designed based on the idea of hierarchical control,and a yaw moment sliding mode controller based on the joint control of yaw rate and sideslip angle is designed.Aiming at the problem that it is difficult to measure the sideslip angle,the yaw rate and the sideslip angle are estimated based on the Extended Kalman Filter algorithm,and the validity and accuracy of Extended Kalman Filter algorithm is verified according the simulations of double lane change and sinusoidal input.Based on the optimization target and constraint conditions,the calculated expected driving torque and expected yaw torque are distributed to each wheel.Finally,the slip ratio controller corrects the driving torque of each wheel,the final driving torque of each wheel is obtained,and the redistribution of driving torque is completed.The simulation results of double lane change and snake cornering show that compared with the control method,which only uses the yaw rate as the control variable and without control,the designed torque coordinated control can effectively improve the vehicle stability.