Design And Analysis Of Pole Changing Memory Machine With Fractional Slot Concentrated Winding

Memory machine is a new type of permanent magnet machine capable of air-gap magnetic field modulation.It not only maintains the merits of traditional permanent magnet machine,such as high power density,high efficiency,and simple structure,but also enables magnetic flux adjustment more conveniently.Moreover,memory machine can be established as pole changing version to achieve wider speed regulation range.Therefore,it is potentially promising for the modern industry,transportation,military,etc.This dissertation proposes a novel fractional slot concentrated winding pole change memory machine(FSCW-PCMM)by combing the concepts of memory machine,pole-changing,and FSCW.The pole-changing mechanism,operation principle,design methodology,characteristic analysis and pole changing speed control technique of PCMM are studied in detail to provide a truly energy-efficient wide speed range permanent magnet machine for industry sectors.Therefore,the basic research work on PCMM is of great theoretical significance and engineering value.In this dissertation,based on the comprehensive review on research status of PCMM,the relevant issues of FSCW-PCMM are analyzed,including the pole changing mechanism,the pole-changing method of FSCW connection,cogging torque of hybrid permanent magnet PCMM and the slot-pole combination of FSCW-PCMM without winding connection variation.A 9 slots-6/2 poles(9s-6/2p)FSCW-PCMM topology is designed and the key parameters are optimized in order to minimize the cogging torque under different pole numbers.The rationality and reliability of the electromagnetic design are verified by employing multi-physical field coupling method.The main research work and achievements in this dissertation are as follows:(1)The research background and the significance of FSCW-PCMM are introduced,respectively.The research state-of-the-art of memory machine,PCMM and FSCW machines are comprehensively reviewed.(2)The pole changing mechanism and the operating principle of PCMM are investigated,respectively.This dissertation explores the winding connection of FSCW before and after pole changing,including the reverse method,phase shift method and hybrid method.The winding factor and magnetomotive force(MMF)of FSCW are analyzed for selecting the slot-pole combination for PCMMs.In addition,the cogging torque calculation formula of the hybrid PM PCMM is derived.(3)According to the variation law of pole changing ratio,the FSCW-PCMM with PM in rotor and stator are put forward respectively.The governing equation for the slot-pole combination of FSCW-PCMM without changing winding connection is presented.In addition,the electromagnetic characteristics of the 8/4 pole-changing machine configurations with different slot-pole combinations and armature winding connections are analyzed.The pole-phase modulation concept of PCMM is proposed,which can further expand the speed range of machine.(4)By comparing the magnetic circuit characteristics of traditional PMSM topologies before and after pole changing,the appropriate topologies of PCMM are summarized and provided.The sizing equations of PCMM are derived,and the electromagnetic design of 9s-6/2p FSCW-PCMM is carried out by using both magnetic circuit method and finite element method(FEM).By using Taguchi array,response surface method(RSM)and genetic algorithm(GA)combinationally,the cogging torques before and after the pole changing are optimized,and the machine parameters are determined.Based on the abovementioned design methodology,the electromagnetic characteristics of the machine can be precisely calculated.(5)The losses of 9s-6/2p FSCW-PCMM are calculated and analyzed.The temperature,stress and deformation distribution of the FSCW-PCMM are respectively calculated and analyzed.The rationality and reliability of electromagnetic design of the machine are verified through multi-physical field coupling method.(6)The mathematical models of PCMM in the stator and rotor coordinate systems are derived respectively.Based on MATLAB/Simulink,the simulation model of PCMM is established,by which the variation laws of the electromagnetic characteristics under constant speed or constant frequency operations are investigated.A prototype is manuficated and measured for experimental verification.