Torque Ripple Reduction Method Of Switched Reluctance Motor Based On Torque Compensation

Switched Reluctance Motor(SRM)speed control system is a new type of mechanical and electrical integration speed control system which integrate modern power electronics technology and microcomputer technology.Because SRM has simple and strong structure,good performance,good reliability,high efficiency,low cost,it has has a great attraction in the field of industry and research.But its double salient pole structure that cause large torque ripple,to a certain extent,hinder its wide application.The traditional Torque Sharing Function(TSF)has a short commutation time at high speed,which makes the actual current hard to track the reference current.The torque ripple is caused by imperfect current in high speed.Torque ripple mainly occurs in three phases which is early stage,late stage of commutation and freewheeling current after commutation.In the early stage,rising phase's tracking performance is too bad while falling phase has the ability to track the reference,which causes torque insufficient in rising phase.On the contrary,falling phase has a perfect performance of tracking in late stage while rising phase has the ability to track the reference current,which makes the falling phase's torque can not decline rapidly like the reference.Because of these shortcomings mentioned above,torque ripples occur.This paper presents a new TSF method based on torque compensation of the three phase mentioned above.In the early stage,falling phase has a strong ability of tracking while rising phase does not.To have a stable sum torque,a corresponding torque is compensated to the falling phase to require it to output a bigger torque.On the contrary,we should compensate the rising phase in the late stage.For the torque caused by the freewheeling current,it can be inhibited by compensate an appropriate torque to another phase.A appropriate difference compesation to the three phase will make the total torque as a constant.The simulation model of switched reluctance motor based on Matlab/simulink is built to verify its effectiveness.The results show that the method can effectively suppress the torque ripple of the SRM.In order to obtain the actual torque,a SRM torque observer is designed for the relationship of current,rotor position and torque is nonlineared.The method of quadratic curve fitting is used in this paper.A standard curve should be getton at first and the others can be derived by the model.The results of Matlab analysis show that the torque observer has accuracy of torque estimation.Finally,a 15kW three-phase 6/4 pole SRM is used as a prototype.The algorithm is written and experimented on the ARM test platform based on TMS320F28335.The correctness of the proposed method is verified.