Optimization Research And Design Of Synchronous Permanent Magnet Motor With Flux-Barrier Rotor

Permanent magnet synchronous motors produce the air gap magnetic fields by using permanent magnetic materials,without exciting windings,excitation powers and reactive excitation currents.Permanent magnet synchronous motors have advantages of high power factor,simple and reliable structure,low loss,high efficiency,energy saving and high power density.However,the air gap magnetic density waveforms produced by the traditional interior permanent magnet synchronous motors are generally rectangular waves.These rectangular waves contain a lot of harmonic contents and have large harmonic wave distortion rates.When driven by sinusoidal currents is,the traditional interior permanent magnet synchronous motors' torque ripples will be high.Some new structure rotors with special types of flux barriers are commonly used to improve the air gap magnetic density waveforms of interior permanent magnet synchronous motors.Such as the rotor with asymmetric distributed flux barriers,the rotor that is made up of laminations with different flux barriers and the rotor with flux barriers that shaped like a rib.These structures can improve the air gap magnetic density waveforms of interior permanent magnet synchronous motors in different degrees.But there are still many problems,such as complex structures,processing and assembling difficulties,and no guarantee of the laminations' mechanical strength when rotational speed is high.In this dissertation,a new structure rotor with flux barriers is proposed to improve the performance of conventional interior permanent magnet synchronous motors after analyzing their characteristics.Because this scheme only makes very small changes to the conventional interior permanent magnet synchronous motors,it has little influence on the structure,so it can effectively improve the air gap magnetic density to a certain extent,and also has the advantage of simple and stable structure,so as to ensure the reliability of the motor.Based on the design method of traditional permanent magnet motors,the main parameters of a prototype were designed.And the initial parameters of the flux barriers of the prototype were designed by using equivalent magnetic circuit model.Then the conventional permanent magnet motor without optimization,the optimized conventional permanent magnet motor and the initial design scheme with new flux barriers were analyzed and compared by the finite element method.The result proved the scientificity and rationality of the initial design.Then the Taguchi method was used to optimize the initial design parameters of the flux barriers.The maximize fundamental amplitude of the air gap magnetic density and theminimum harmonic distortion rate were set as optimal objects.The four parameters of the flux barriers were set as the optimal factors and then the orthogonal experiment was designed.Finally,the optimized conventional motor without new flux barriers,the initial design scheme with new flux barriers and the scheme optimized by Taguchi method were analyzed and compared.The result indicated that fundamental amplitude of the air gap magnetic density and the harmonic distortion rate the scheme optimized by Taguchi method were better than the optimized conventional scheme and the initial scheme.