Design And Analysis Of Axial-flux Flux-modulation Permanent-magnet Machines

With the continuous development of Chinese urbanization,urban rail transit is becoming the backbone of urban public transport due to advantages such as large capacity,safety,punctuality and high speed,high efficiency and low carbon emission.Meanwhile,since the volume of urban rail transit is quite large,it is high energy consumed,which makes energy conservation and emissions reduction an important issue in the development of Chinese urban rail transit.In recent years,the permanent magnet direct-drive traction system has drawn more and more attention because of its low power consumption,high power density and low noise,which makes it have wide application prospect in railway transportation field.Based on the current condition and challenge of the permanent magnet direct drive traction system,this paper cooperates flux modulation machines with permanent magnet direct-drive traction system and proposes an axial-flux flux modulation machine for direct-drive traction system.Based on the current condition and challenge of the permanent magnet direct drive traction system,this paper cooperates flux modulation machines with permanent magnet direct-drive traction system and proposes an axial-flux flux modulation machine for direct-drive traction system.By reviewing existing flux modulation machines and axial-flux topologies,a multi-air-gap axial-flux flux modulation topology named triple-rotor axial-flux spoke-array vernier permanent magnet(TR-AFSAVPM)machine is proposed in this paper.For the theoretical analysis,equivalent magnetic circuit model of the proposed machine is firstly established.By cooperating with the winding function,analytical equations of the machine airgap permeance,back-EMF and torque are given.For the machine design,a set of primary main parameter specifications is determined based on design experiment and quasi-3D finite element analysis(FEA).After that,analytical equations,quasi-3D FEA and 3D FEA are applied to determine the machine performance.The relationship between machine pole ratio and performances are also investigated.Moreover,by comparing with several conventional vernier machines and another multi-air-gap axial-flux flux modulation topology called triple-stator axial-flux spoke-array vernier permanent magnet(TS-AFSAVPM)machine,advantages of the TR-AFSAVPM machine is revealed.For the optimization,this paper chooses multiobjective genetic algorithm for settling the final design.For experiment,a proper control strategy is determined firstly.A prototype is designed,manufactured and tested.The multi-air-gap axial-flux flux modulation topology proposed in this paper not only can improve the low power factor and long end-winding length issue in conventional vernier machines,but also enhances the machine torque density and lower its copper losses.Therefore,it is suitable for direct-drive traction applications.