Research On Regenerative Braking Control Strategy Of Switched Reluctance Motor For Electric Vehicle

Environmental pollution and energy shortage have accelerated the transformation of the automobile industry.Electric vehicles(EVs)have become the research focus of the automobile industry because of the advantages such as non-pollution and high energy utilization.Compared with traditional cars,EVs can recover braking energy,which can effectively improve the range,so the regenerative braking technology of EVs has become a research hotspot.As the core part of regenerative braking of EVs,how to choose the proper motor is the most important part.Switched reluctance generator(SRG)is considered to be one of the best choice for the electric car energy recovery.Therefore,this paper focuses on four aspects of the 8/6 SRG to make the investigation which are respectively electromagnetic field characteristics analysis,dynamic modeling,multi-objective optimization and simulation analysis of EVs regenerative braking system.Firstly,the finite element model of SRG is established by Maxwell software,and the characteristics of electromagnetic field are analyzed.The experimental scheme of static electromagnetic field of SRG is designed by indirect method.The values of flux linkage and torque are obtained by numerical analysis,and the accuracy of electromagnetic characteristics obtained by finite element analysis is verified.Secondly,the nonlinear dynamic model of SRG drive system is established under MATLAB/Simulink environment.Based on analysis of waveforms from the SRG phase currents,and two control models of low speed current hysteresis loop and high speed single pulse are established.Furthermore,in order to improve the ride comfort,range and battery life of EVs,three optimization indicators are proposed which are torque smoothness coefficient,output power and current smoothness coefficient.By off-line data collection,the effects of the control parameters of the SRG on the optimization indicators under the two operating conditions of low speed and high speed is analyzed respectively.In order to improve the comprehensive performance of SRG drive system for EVs,a multi-objective synchronous optimization control strategy is proposed,a multi-objective optimization function is constructed,and a multi-objective optimization controller based on variable turn-on angle and turn-off angle is designed.Through comparison and analysis with the output power optimization control strategy,the feasibility of the multi-objective optimization control strategy proposed in this paper is verified.Finally,the dynamic model is established based on parameters of EV.The front and rear wheel braking force distribution scheme is designed based on the braking intensity;A strategy of regenerative power distribution based on maximum energy recovery is proposed;Based on the EV braking system model,three kinds of conventional braking conditions are studied and the braking energy recovery characteristics of the optimized SRG in regenerative braking system is tested.