Study On Handling Stability Of Electric Vehicle With Hub Motor Based On CARSIM

With the development of automobile industry,the global automobile production and sales is increasing year by year,which not only aggravate the global petroleum energy crisis,but also its exhaust emission becomes one of the important factors of city air pollution.As no need for fossil fuels,zero emissions and zero pollution,electric vehicles is gradually being recognized by the global automotive industry.The hub motor technology is an important direction of the development of electric vehicles,study on handling stability of electric vehicle with hub motor has very important theoretical significance and practical significance.Taking four wheel drive SUV as the prototype,two freedom degrees model for four wheel independent steering system of electric vehicle with hub motor is established;according to the feed forward control strategy of the front wheel steering angle,the relationship between rear wheel steering angle and front wheel steering angle is discussed and analyzed;programming by MATLAB,the relationship between the gain coefficient of the feed forward of the front wheel steering angle and vehicles longitudinal velocity is obtained.By Simulink of MATLAB,the rear wheel steering angle model based on the front wheel steering angle and vehicle’s longitudinal velocity is established,and the motor model based on the motors external characteristics is established too.Using S-Function of CARSIM,combined the four wheel steering model and motor model in Simulink with the traditional vehicle model,brake model,suspension model,tire model and driver model in CARSIM is simulated,a combined simulation model of four-wheel drive SUV electric vehicle with hub motor is established.Based on the simulated model,vehicle longitudinal speed,wheel motor output speed and torque are observed by constant acceleration test,vehicle yaw angular speed,lateral acceleration and vehicles four wheel steering angle are tracked by the fixed steering angle test,it is shown that the established hub motor model has high accuracy,and the established four wheel steering model has high feasibility.Using the established models,the double lane change test and the steady-state rotation test are done respectively,the important factors influenced the handling stability are analyzed,the handling stability of electric vehicle with hub motor and traditional central drive vehicle are compared,it is shown that,even the hub motor significantly increases the non-sprung mass and wheels inertia moment,the handling stability of electric vehicle with hub motor distribution drive has more advantage than traditional central drive vehicle.It is comprehensively shown that the established simulation models could study the handling stability of four wheel independent drive electric vehicle with hub motor.