Design And Analysis Of A Novel Stator Flux-concentrating Permanent Magnet Memory Machine

Variable flux memory machine(VFMM)utilizes either stator armature windings or additional DC magnetizing coils to change the magnetization state(MS)of low coercive force permanent magnet(LCF PM)by temporary remagnetizing/demagnetizing current pulses.In this way,the air-gap flux can be flexibly adjusted,and the excitation loss during the MS adjustment process can be neglected,which well addresses the issue of the non-adjustable airgap magnetic field as well as limited speed range of the traditional permanent magnet synchronous machine(PMSM),realizing the globally high efficiency operation.Therefore,VFMM is promising for electric vehicle,rail transport,aerospace and other fields.This thesis comprehensively analyzes the current research of VFMM at home and abroad,and then a novel stator flux-concentrating permanent magnet memory machine(SFCPM-MM)is proposed,combining the principle of slot permanent magnet and doubly salient permanent magnet(DSPM)machine to resolve the shortcomings of the existing DC-magnetized VFMMs.In this thesis,SFCPM-MM is regarded as the research objective,and its topology evolution,operation mechanism,design optimization,electromagnetic characteristics and experimental validations are studied.The main research work of the thesis includes the following aspects:(1)Introduce the research background and significance of the subject,and summarize the current research of VFMM at home and abroad.In order to overcome the shortcomings of the current VFMM topologies,a novel SFCPM-MM is proposed to illustrate the novelty of this thesis.(2)Reveal the topology evolution of the novel SFCPM-MM,and choose the appropiate stator structure.Through the analysis of the hysteresis model of LCF PM,the flux regulation principle of VFMM is illustrated.The simplified magnetic circuit models of SFCPM-MM are built,and the operation principle as well as flux regulation mechanism of SFCPM-MM are analyzed.(3)After the parameter initialization of SFCPM-MM,the finite-element models of T-type and П-type SFCPM-MM are built.The slot-pole combination is subsequently analyzed,and the geometric parameters are optimized.(4)Based on the optimal design,the electromagnetic performance of T-type SFCPM-MM and П-type SFCPM-MM are compared and analyzed,confirming that the П-type structure has superior electromagnetic performance.(5)The П-type SFCPM-MM prototype is manufactured,and the test platform is set up.The experimental tests in terms of the remagnetizing/demagnetizing characteristics and other main electromagnetic performance of the prototype are carried out.The research work in this thesis provides a theoretical and technical basis for the further study of the hybrid PM VFMM with DC magnetizing coils.