Comparison Between Linear Induction Motor and Linear Flux-switching Permanent-Magnet Motor for Railway Transportation

Linear induction motors (LIMs) have been extensively adopted in urban railway transportation given their non-adhesion thrust and simple stator structure. However, these LIMs undergo unfavorable power factor and efficiency considering the copper and eddy losses of them. Recently, linear flux-switching permanent-magnet motors (LFSPMs) have attracted the attention of researchers due to their high power density, simple structure, easy heat dissipation, high efficiency and high power factor. However, so far, no quantitative comparison exists between LFSPMs and LIMs in the size of 1:1 to prove the feasibility for LFSPMs to be used in railway transit systems. Therefore, a comparative analysis between the two motors is also conducted. First, this study investigates the LIMs for railway transit using finite element method (FEM). Second, the LFSPMs for railway transit is designed and optimized. Third, the electromagnetic performance of the two motors are compared and analyzed through the FEM. Finally, a prototype of the LFSPMs is constructed in a small size to validate the FEM results. It is concluded that LFSPMs offer a favorable thrust force, have high efficiency, and high power factor but have large normal force and force ripple. Therefore, applying LFSPM requires reliable supporting device and shock absorber.