Optimization Design And Performance Analysis On Three-Phase Switched Flux Permanent Magnet Machine

With the gradual development of electric vehicles become the trend of urban transportation tools,electric drive equipment has higher requirements for motor performance,permanent magnet synchronous(PMSM)machine with new topology has become a research hotspot.Switched flux permanent magnet(SFPM)machine combines the advantages of PMSM machine with high power density and high reliability of switched reluctance(SRM)machine at high speed.Moreover,the SFPM machine can be controlled by the traditional AC synchronous machine drive mode,there is no need of additional drive costs,it can meet the requirements of electric vehicle for its drive motor.In this paper,the development of permanent magnet machine at home and abroad is briefly introduced.The proposal and development of SFPM machine and its new topologies are mainly introduced.Then the research background of machine optimization design is introduced.The machine model of d-q axis coordinate is established,and the basic structure and working principle of SFPM machine are explained in detail.Secondly,by taking a 6/8 SFPM machine as example,the sensitivity of parameters is investigated to decide the optimized sequence.With the different constrains,such as light-load?rated?over-load conditions,the optimization of 6/8 SFPM machine is carried out at fixed copper loss?fixed current?fixed current density.By comparing the torque density,PM volume,losses and efficiency of the optimized designs,the effective constraint to optimize the SFPM machine will be obtained in this paper.Four SFPM machines with different combinations of stator and rotor pole numbers are presented,including 12/10,6/5,12/16 and 6/8 SFPM machines.With the optimization of the electromagnetic torque,the main design parameters are determined.The electromagnetic torque?cogging torque?flux-linkage?back-emf?loss?efficiency?flux weakening capability and permanent magnet volume of each machines are compared.It is shown that compared with 12 stator pole SFPM machines,the output torque per magnet volunes and efficiency of 6 stator pole SFPM machines is lower.However,,the flux weakening capability of 6 stator pole SFPM is better.Finally,two topologies of 6/8 pole hybrid excitation switched flux permanent magnet machines are proposed,and the magnetic modulation performance of these two motors is analyzed and compared.Firstly,the basic structures and main design parameters of the machines are introduced,and the principle of magnetic modulation is compared.By analyzing the fluxlinkage,torque and d-axis inductance in different direction and magnitude of excitation current density,the motor structure with better magnetic regulating performance is obtained.