Topology Optimization And Magnetic Field Analysis Of Permanent Magnet Synchronous Traction Motor For Urban Rail Train

Permanent magnet synchronous motor(PMSM)has the advantages of high power density,high power factor and high efficiency.Compared with asynchronous motor,it simplifies the mechanical transmission structure,and is convenient to adopt various new energy technologies.It is an ideal choice for urban rail train traction system.The advantages of PMSM in the traction system of urban rail trains are mainly reflected in the realization of the quantitative design and fully enclosed design of traction motors,which can reduce the unsprung weight of bogies ang effectively isolate noise.However,PMSM has some problems,such as temperature rise,large torque ripple,air gap magnetic density distortion and demagnetization fault.Therefore,according to the operation requirements of urban rail trains,it is very important to develop permanent magnet synchronous traction motors with high power density,high reliability and low emission(including low energy consumption,low vibration noise and low electromagnetic interference)from the ontology optimization design of PMSM.The research contents include:(1)According to the structure and operational performance requirements of urban rail trains,a model PMSM with rated power of 30 k W,rated speed of 1500 rpm and rated torque of191N·m is preliminarily designed.The finite element model of the model motor is constructed for preliminary simulation,and the rationality of the design and the electromagnetic performance of the motor are analyzed.(2)Aiming at the key technical problems of PMSM,starting from the optimization of magnetic pole topology,a central segment magnetic pole structure is proposed.Taking the segmented Halbach PMSM in the cross center as an example,the vector magnetic potential of each subdomain of the motor under no-load,armature reaction and load is solved by the exact subdomain model method,and then the analytical expressions of air-gap magnetic field distribution,cogging torque and electromagnetic torque of the motor under no-load and load are derived.The analytical solution is compared with the finite element simulation results to verify the correctness of the analytical method.At the same time,a hierarchical multi-variable multi-objective optimization algorithm is proposed to optimize the magnetic pole topology of Halbach PMSM with cross-shaped central section,and the electromagnetic performance of other eight magnetic pole structures is compared and analyzed,which verifies the superiority of Halbach PMSM with segmented magnetic pole central section.(3)On the basis of pole topology optimization,aiming at the problems of permanent magnet synchronous traction motor,such as difficult adjustment of excitation field and irreversible demagnetization of permanent magnet.Starting from optimizing the overall topology of the motor,based on the principle of magnetic field modulation and hybrid excitation,a flux-concentrating hybrid excitation field-modulated permanent magnet(FCHEFMPM)traction motor with external rotor is obtained.After optimization,it is compared with surface-mounted hybrid excitation field-modulated permanent magnet(SMHEFMPM)traction motor.On the basis of simulation optimization,the electromagnetic performance and mechanical characteristics of FCHEFMPM traction motor with outer rotor under different working conditions are analyzed.