Study Of Line-start Reluctance Assisted Permanent Magnet Motor

Most of the current line-start permanent magnet synchronous motors(LSPMSM)use NdFeB permanent magnet materials,and these motors have a large amount of permanent magnets and high manufacturing cost.However the permanent magnet reluctance motors are evolved from the synchronous reluctance motor(SRM).Its salient ratio and the utilization of reluctance torque in the output torque is much larger than ordinary motors.Therefore,for the same size of the motor,it can save many permanent magnets.And it also has similar power density and efficiency with rare earth permanent magnet motors.This makes it has a lower manufacturing cost.But it can't start asynchronously.In view all of this,this paper proposes to replace the line-start permanent magnet synchronous motor(LSPMSM)with a line-start reluctance assisted permanent magnet motor.This paper first introduced the development and research status of line-start permanent magnet synchronous motor and permanent magnet assisted synchronous reluctance motor;and aiming at the problems existing in these two kinds of motors,it proposed to replace the line-start permanent magnet synchronous motor with line-start reluctance assisted permanent magnet motor.Secondly the principle of reluctance torque of line-start reluctance assisted permanent magnet motor is expounded.And it discussed the variation of the salient ratio and reluctance torque utilization of the motor under different permanent magnet layers and different permanent magnet thicknesses.It also discussed the variation of this motor when it has different number of rotor slots and slot width.Then it analyzed the situation when using ferrite permanent magnet materials.Thirdly,based on the above analyses it determined the rotor structure of the motor and designed a 3kW line-start reluctance assisted permanent magnet motor.Subsequently,this paper analyzed the process of line-start reluctance assisted permanent magnet motor theoretically.And it also calculated the stall current,stall torque and starting performance of the motor by finite element analysis method.Finally,by comparing with line-start permanent magnet synchronous motor,it summarized the advantages and disadvantages of the line-start reluctance assisted permanent magnet motor.In this paper,the variation law of salient ratio and reluctance torque utilization is obtained by simulation analysis of different rotor structures,which provided a reference for the further design of line-start reluctance assisted permanent magnet motors.