Research On The Method Of Suppressing Torque Ripple For Switched Reluctance Motor

Switched Reluctance Motor(SRM)has developed rapidly since it has the advantages of simple structure,strong fault tolerance,large starting torque,and suitable for high-temperature and high-speed operation,etc.However,the special double salient structure of SRM causes its electromagnetic characteristics to have strong nonlinearity and strong coupling,which causes the problem of large instantaneous torque ripple in SRM.Excessive torque ripple will affect the speed regulation performance of SRM.Therefore,it is of great significance to study the torque ripple of SRM and propose effective methods to reduce the torque ripple.In this paper,a three-phase 12/8-pole switched reluctance motor is taken as the research object.The electromagnetic data of SRM is obtained by finite element software,the model of nonlinear ontology and control system of the motor are established.Then,the SRM control algorithm is researched.Firstly,considering the situation that the current chopping control is often used when the SRM is running below the base speed,aiming at the problems of weak current dynamic tracking ability and large torque ripple in commutation region in traditional current chopping control,a current soft chopping control strategy based on reference current compensation is adopted according to the change characteristics of inductance curve.The improved current chopping control strategy can enhance the torque output capability and dynamic response capability of the winding in the commutation process.Secondly,in order to further improve the operation performance of SRM,the direct instantaneous torque control method is applied.Based on the traditional direct instantaneous torque control,an optimization strategy of turn-on angle and turn-off angle is proposed.The turn-on angle and turn-off angle are dynamically adjusted online to change the turn-on interval of excitation phase to achieve the purpose of torque regulation.The improved direct instantaneous torque control strategy takes the output instantaneous torque to follow the reference torque as the target,and converts the torque ripple problem of SRM into the error control and switching angle adjustment problem between the instantaneous torque and the reference torque.While reducing the torque ripple of the motor,the current waveform is optimized and the efficiency of the motor is improved.Finally,a hardware-in-the-loop experimental platform based on RT BOX is built.Considering the operating conditions of the motor at different speeds and loads,the current chopping control and the direct instantaneous torque control are experimentally verified.In the experiment,the torque ripple coefficient index is applied for comparison.The simulation and experimental results show that the improved control method can effectively reduce the torque ripple of the switched reluctance motor and improve the performance of the motor.