Thermal Analysis And Structure Optimization Of A Hybrid Excited Axial Field Flux-switching Machine

Hybrid excitation axial field flux-switching(HEAFFS)machine is a novel hybrid excitation machine which inherited the merits of axial field machine,hybrid excitation machine and flux-switching machine.In this dissertation,some critical issues of a three phase 6/10-poles HEAFFS machine is investigated,including the operating principle,electromagnetic characteristics,temperature distribution,structure optimization and different topologies,by which a systematic and effective method is sought for the thermal management and structure design of HEAFFS machine.The research works of this dissertation mainly consists of the following aspects:1.The basic structure and operating principle of HEAFFS machine are analyzed in detail.The static electromagnetic characteristics of the machine are investigated by 3-D finite element analysis(FEA)method,including the flux linkage at no-load,back electromotive force(backEMF),cogging torque,output torque and flux regulation capacity.2.The heat transfer inside the HEAFFS machine is investigated.A 3-D equivalent thermal network is set up based on the theory of lumped-parameter thermal network(LPTN)model.The temperature distribution of HEAFFS machine can be obtained by calculating the thermal resistance between the nodes and the heating power of the heat source nodes.The temperature field distribution of HEAFFS machine is also calculated by fluid-temperature field coupled three-dimensional finite element analysis,and the result of both methods are in consistence.And the feasibility of both methods is verified by the thermal experiments of the HEAFFS machine.3.The influence of the HEAFFS machine design parameters,such as the stator yoke thickness,stator side tooth width,stator middle tooth width,PM thickness and rotor pole width,on the electromagnetic torque,cogging torque,flux regulation capacity,loss and efficiency is analyzed.In overall consideration of the THD of back-EMF,the ratio of electromagnetic torque and cogging torque and the highest steady temperature of the HEAFFS machine,the structure parameter are optimized based on the design of experiment(DOE)method and an optimized prototype is obtained.4.The electromagnetic torque,cogging torque,flux regulation capacity,loss and efficiency of the HEAFFS machine with twisted stators,segmented twisted rotor,fan-shaped rotor poles and different number of rotor poles are analyzed.In overall consideration of the THD of backEMF,the ratio of electromagnetic torque and cogging torque and the highest steady temperature,structure parameters and topology representation variable of the four structures of HEAFFS machine are optimized.The electromagnetic characteristics and temperature of the optimized structures are compared and the effectiveness of proposed structures in improving the performance of the HEAFFS machine is analyzed.