Study On Traction Control Algorithm For Four-wheel Drive Electric Vehicle Under Low Adhesion Conditions

With the energy crisis and environment pollution becoming more and more serious,Electric vehicle has become a development new subject of automobile industry because of its efficient use of renewable and clean energy,almost zero emission and centralized transfer treatment of its own pollution.Four-wheel drive electric vehicle has become a study hotspot in electric vehicle because of its high transmission efficiency,more energy-saving and more intelligent development foundation.Traction Control System(TCS)is the core technology of electric vehicle safety technology.Its main function is to enable vehicle to make full use of road adhesion and improve driving performance.Therefore,the development of TCS with excellent performance is of great significance to the development of electric vehicle.Aming at the excessive sliding problem of Electric Vehicle driving wheel in working conditions that snow and ice with Low adhesion coefficient,based on road surface fuzzy recognition,slip rate and adhesion coefficient are defined as piecewise approximate linear model,and TCS sliding mode controller is designed to improve vehicle driving performance,the main work is as follows:(1)The transmission characteristics of four-wheel drive electric vehicle were studied in detail.On this basis,the wheel skidding mechanism in vehicle driving was studied.Then,the TCS control way and common control algorithm of electric vehicle were studied in depth.On the basis of the above research,the vehicle system model is established in Trucksim as the application object.(2)A road surface fuzzy identification controller is designed by using real-time vehicle use adhesion and slip rate as input variables.By using the designed road surface fuzzy identification controller,the maximum adhesion and optimal slip rate of the current road surface can be accurately identifiy.(3)The adhesion coefficient and slip rate are defined a s piecewise approximate linearity.The TCS sliding mode controller is designed with the real-time slip rate as the target state variable and the driving motor torque as the control variable.Finally,union simulation experiment is carried out by connect the whole vehicle system model established in Trucksim.The simulation results illustrator that the designed road fuzzy recognition controller can accurately identify the maximum adhesion coefficient and the optimal slip rate of the current running road surface of vehicle.TCS sliding mode controller can control the actual slip rate of the vehicle near the optimal target slip rate by controlling the torque of the driving motor,which greatly improves the driving performance and stability of the vehicle under conditions that snow and ice with Low adhesion coefficient.