Study On Torque Ripple Suppression Of Switched Reluctance Motor Based On Unipolar Sinusoidal Excitation

With the rapid development of modern power electronics and high-power transistors,SRM has been widely studied by many domestic and international scholars.And SRM has the advantages of simple structure and strong,low cost,high reliability,wide speed range,large starting torque and good dynamic response,etc.However,the torque ripple of SRM is large and its application range is limited,because of the double salient structure and power supply in switch form.Therefore,how to reduce the torque ripple of SRM has become the research focus.In this paper,a torque ripple suppression method based on current vector decomposition is proposed to realize SRM torque ripple suppression.Firstly,this paper introduces the research status of SRM torque ripple suppression from three aspects:SRM body structure,SRM precise modeling and SRM control strategy.Then,the finite element model of SRM is established by Maxwell software,and the electromagnetic and static characteristics of SRM are analyzed.The mathematical expressions of flux,inductance and torque are given through analysis.In order to improve the accuracy of SRM drive system simulation model,the parametric analysis of phase current and rotor position angle is carried out.And the nonlinear flux and torque characteristic data of SRM can be obtained.Then the nonlinear motor model is established by Matlab/Simulink.Finally,the SRM current chopper control simulation is built to verify the correctness of the model.Then,according to the SRM mathematical model in the static coordinate system and coordinate transformation principle,the voltage,current and torque mathematical model in the rotating coordinate system is derived.By analyzing the torque formula in the rotating coordinate system,it can be known that the torque ripple can be reduced by injecting the third harmonic current into the DC bias current4)₀.The feasibility of the control strategy and the correctness of the theoretical analysis are verified by simulation.In addition,the DC bias current4)₀ of unipolar sinusoidal current is optimized.The results show that the copper consumption and torque ratio is the best when4)₀=4).In order to further reduce the torque ripple and the negative torque generated by SRM under unipolar sinusoidal excitation,two methods of constant4)unipolar excitation control and variable4)unipolar excitation control based on current vector decomposition are proposed in this paper.And a new SRM torque model satisfying the magnetic saturation is established so that variable4)unipolar excitation control method can satisfy the magnetic saturation.Finally,the feasibility of the control strategy and the correctness of the theoretical analysis are verified by simulation.At the last part,this paper introduces the soft and hard structure of the experiment platform of the SRM.And the proposed optimal control strategy of torque ripple is verified by experiments.The experiment results show that the torque ripple minimization control strategy proposed by this paper is feasible and effective.There are 67 figures,6 tables and 84 references in this paper...