Control And Structure Parameter Optimization Of Unipolar Sinusoidal Excitation Switch Reluctance Motor

Switched reluctance motor(SRM)is a new type of motor with simple structure,stable performance,low maintenance cost and high operating efficiency.The traditional square wave current excited switched reluctance motor has strong output torque capacity,simple control and easy maintenance,but the torque fluctuates greatly,and the operation at medium and low speed will produce large vibration noise.In view of these problems existing in traditional excitation methods,scholars at home and abroad have carried out many researches on reducing torque ripple and vibration noise.Starting from the body structure of switched reluctance motor,this paper first introduced the electromagnetic design process of the basic structural parameters of switched reluctance motor,and then conducted finite element analysis of the static electromagnetic characteristics of the motor through Maxwell software,including the key magnetic field characteristics of the motor such as magnetic linkage characteristics,inductance characteristics and moment Angle characteristics.Second,the principle of single-polarity sine excitation of switched reluctance motor with three-phase 12/8 structure is analyzed.Under the excitation of single-pole current,dc component generates(virtual)rotor flux,while ac component generates rotating stator magnetic field,the interaction between the rotor flux and the stator magnetic field produces electromagnetic force.Thirdly,the mathematical model of switched reluctance motor under unipolar sinusoidal excitation is derived,and the output equations of voltage and torque of three-phase and four-phase switched reluctance motors in stator coordinate system and rotor coordinate system are obtained.The paper focuses on the quantitative analysis of the average torque generated by the three-phase switched reluctance motor under unipolar sinusoidal excitation.By means of finite element analysis and Fourier analysis,the function equations of the mean torque,the AC/DC component of the excitation current and the pole arc of the three-phase switched reluctance motor are established,and the optimal rotor pole arc and other structural parameters corresponding to the maximum average torque are obtained.The vector control strategy of three-phase switched reluctance motor based on maximum torque current ratio control is studied.The advantages of the proposed control strategy in suppressing torque ripple and vibration noise are verified by multisoftware co-simulation.Finally,the control algorithm of four-phase switched reluctance motor is studied,and the instantaneous electromagnetic torque equation shows that the four-phase switched reluctance motor does not generate reluctance torque when the unipolar sinusoidal current is excited,thus greatly reducing the torque ripple.A new vector control for four-phase switched reluctance motor is adopted.The switched reluctance motor asymmetrical half-bridge power converter is equivalent to two inverters,which control the torque component and the excitation component respectively.On the experimental platform of four-phase switched reluctance motor,vector control experiments are carried out.Finally,the vibration noise of four-phase SRM under unipolar sinusoidal excitation is analyzed.There are 83 figures,8 tables and 82 references in this paper.