Research On Torque Ripple Suppression Strategy Based On Vehicle Permanent Magnet BLDCM Regenerative Braking Control

The report of the 19th National Congress pointed out that Chinese socialism has entered a new era.In the new era,people have an urgent desire and need for a better life.Among them,"green mountains and green mountains".However,environmental problems have become increasingly serious in recent years,especially in urban smog,mainly because of the large amount of exhaust gas emitted by automobiles.Traditional cars burn oil to provide power,and a large amount of exhaust gas emits severe urban haze.In this context,electric vehicles came into being.During the regenerative braking process of the electric vehicle,the motor provides the braking current.At this time,the braking current generates the braking torque,and the electric vehicle performs the deceleration braking.At the same time,the power is fed back to the battery,which is economical and environmentally friendly,and can extend battery life.Therefore,research on regenerative braking is very valuable.On the basis of the predecessors,this paper firstly introduces the working principle of the BLDCM.According to the common two-way conduction method,the different modulation modes of the current BLDCM electric operation are simply compared and analyzed,and the motor’s mathematical model is established.Secondly,it is pointed out that the basic principle of BLDCM realize regenerative braking is the boost chopper circuit.Based on this,the reasons for the regenerative braking torque ripple and how to suppress the torque ripple are studied.Then the controller of the motor is designed.This paper mainly analyzes the two types of regenerative braking torque ripple,one is the non-commutated torque ripple caused by non-conducting phase continuous flow,and the other is the commutated torque ripple caused by non-commutated current fluctuation during regenerative braking commutation.For the non-commutated torque ripple,this paper compares and analyzes the current flow path and the motor state equation of the ordinary half-bridge feedback PWM-OFF and H＿OFF-L＿PWM modulation methods,the full-bridge modulation method,and finds the problems of these modulation methods.In short,a new half-bridge PWM-OFF-PWM modulation method is proposed,which can solve the problem of non-commutated torque ripple caused by non-conducting phase flow and energy not being fully fed back.For the commutation torque ripple,the qualitative and quantitative analysis of the commutation torque ripple is carried out.Based on the traditional overlapping commutation control strategy,an overlapping commutation control strategy with dynamic adjustment and precise determination of commutation time is proposed to suppress the commutation torque ripple.Finally,based on the PLECS simulation software,a simulation model is built to verify the proposed torque ripple suppression strategy.Based on theoretical analysis and simulation verification,a hardware platform for regenerative braking control system of permanent magnet BLDCM is established.Finally,through simulation and experiments,it is concluded that the new PWM-OFF-PWM modulation method combined with the commutation time can dynamically adjust the accurately determined overlap commutation control strategy can suppress the non-commutated torque ripple,achieve full energy feedback and suppress the commutated torque ripple,the motor’s current square wave characteristics are good.