Study On The Torque Distribution Of Four In-wheel Motor Pure Electric Vehicle

With the energy and environmental problems of human society having become increasingly prominent,high-efficiency,pollution-free pure electric vehicles are becoming a research topic around the world.Compared with conventional internal combustion engine vehicles or centralized driving electric vehicles,the drive and brake torque of four in-wheel motors pure electric vehicles is independent and controllable,which benefits to the control of vehicle dynamics,facilitates the integrated control of the chassis and meet the development trend of intelligent cars.Therefore,this paper is focused on the study of drive torque of four in-wheel motors pure electric vehicle through controlling and distributing the drive torque to improve the stability and economy of the vehicle.The project supported by Natural Science Basic Research Plan in Shaanxi Province of China“Research of Braking Stability for Four-wheel Independent Actuated Electric Vehicle”(Program No.2017JM5139).The study of torque distribution control of four in-wheel motor electric vehicle is based on the longitudinal dynamics of vehicle and combined with the relevant theories and basic algorithms of torque distribution control.Then the drive torque control strategy of whole vehicle was proposed.At first,the actual slip ratio of the wheel and the adhesion coefficient of the road surface are obtained according to the dynamic parameters of the vehicle model.Then,The optimal slip rate was obtained through the road recognition controller which was based on the T-S fuzzy model.What’s more,whether the anti-slip controller is involved in the control is determined by the slip state judgment module.The anti-slip controller controlled the wheel slip rate near the optimal slip rate by outputting the adjustment torque.In order to improve the economic efficiency of the entire vehicle when it does not slip,an optimal function of the entire vehicle drive efficiency was established.The vehicle entire torque is distributed according to the optimal distribution coefficient.Finally,a co-simulation platform suitable for four in-wheel motors pure electric vehicles is established through the CarSim and Simulink software.The designed control strategy was verified by co-simulation.The consequence of the simulation showed that the designed control strategy couldcontrol the slip ratio of the wheel near the optimal slip ratio when the wheel slipped,which effectively improved the stability of the vehicle;When the vehicle does not slip,through the ECE and JPN-1015 cycle conditions,compared with the average distribution,the designed optimal torque distribution algorithm can reduces energy consumption by 6.29% and 4.67%respectively.It is showed that the designed optimal distribution efficiency can improve the economy of the vehicle to a certain extent.