Study On Regenerative Braking System Of Four In-wheel-motor Actuated Electric Vehicle

Electric Vehicle(EV)were hot topics that appeals to very strong research interests around the world,with the increasingly serious problem of environmental pollution and energy crisis.The four in-wheel-motor actuated EV simplifies conventional mechanical transmission system,and each in-wheel-motor can be arbitrarily matched according to requirements.The driving and braking torque of each in-wheel-motor can be controlled quickly,accurately and independently.Besides,in the aspect of vehicle chassis layout,energy-saving optimization,dynamics control and so on,four in-wheel-motor actuated EV have many advantages.However,constrained by battery technology,the EV's battery charging speed is slow and the driving range is short,it is therefore an urgent problem to be solved is increasing energy utilization rate.There is more braking energy are consumed when EV is working under urban traffic condition,and Regenerative Braking System(RBS)have been developed to enable recuperation of EV's kinetic energy during deceleration or braking condition,and increases energy utilization rate.At the same time,the wear of friction brakes is reduced and vehicle dynamics control performance is improved.Certainly,the energy recovery advantages of four in-wheel-motor actuated EV than conventional EV,since the regeneration energy can be recycled by four in-wheel-motor.Therefore,it is important to research the RBS for four in-wheel-motor actuated EV.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).In this paper,the structural features of four in-wheel-motor actuated EV,the influencing factors of RBS,the operating performance of motor,battery and hydraulic brakes are analyzed.Thus,a matching method of EV power-train system is proposed that focused on maximizing regeneration energy,and a new RBS control strategy is designed which can be used to improve energy recovery rate and braking smoothness performance.Based on the experimental development circuit board for brushless DC motor,the working principle of motor,the motor control theory of RBS and so on.,a motor control scheme for RBS is proposed,and a hardware circuit of RBS controller is modified and designed.Moreover,the RBS control program is written in MPLAB X IDE environment.The RBS simulation model of four in-wheel-motor actuated EV is designed based on MATLAB/Simulink,Isight and CarSim,next the matching method and RBS control strategy are studied,verified and optimized by this model.The simulation results show that the designed matching method is suitable for four in-wheel-motor actuated EV,the four in-wheel-motor and battery are selected that can realize maximize regeneration energy,and the effect of regeneration energy rate and braking smoothness is obvious when designed RBS control strategy is actuated.In addition,the RBS controller and program are tested on test bench of small EV transmission experiment bench.The experiment results show that the design objectives are realized and the control performance is effective for RBS.