Research On Control Algorithm And Design Of Power Convertere Of Switched Reluctance Motor For Electric Vehicle

With the aggravation of environmental pollution and energy crisis,the concept of green travel has been deeply rooted in people's mind,and electric cars have attracted more and more attention.Switched reluctance motor has the advantages of simple structure,large output torque,small starting current and good controllability.It is very suitable for electric vehicles.In view of the problem of large current ripple when current soft chopper control is applied to switched reluctance motor,this paper improves the control algorithm to reduce the current ripple.At the same time,in order to improve the reliability of the drive system of switched reluctance motor,a five-level power converter is designed and the corresponding fault-tolerant control strategy is proposed.In this paper,the reason of large current ripple when using traditional current chopper control method is analyzed.Combined with pulse width modulation(PWM)and piecewise control,a subsection PWM variable duty cycle control of switched reluctance motor based on current soft chopping is proposed.Different duty cycles of excitation and demagnetization are adopted according to the motor speed,rotor position and reference current to achieve better current tracking effect.Through simulation,the optimal duty cycle at different speeds and reference currents is obtained,and the duty cycle-speedcurrent function is fitted,which achieves better dynamic results.Because the commonly used asymmetric half-bridge power converter has fewer switching devices,it can not meet the requirements of excitation and demagnetization voltage of switched reluctance motors under different working conditions,especially when the power converter has open-circuit fault,it is difficult to carry out fault-tolerant control.In this paper,a five-level power converter is designed,which has a variety of working modes.It can not only meet the different requirements of excitation and demagnetization voltage of motor at low speed and high speed,but also has good faulttolerant control ability for open-circuit faults of power converter.Finally,the proposed control algorithm and topology are verified by simulation and experiment.