Design and analysis of a new HTS modular flux-switching linear machine for rail transit

摘要

This study proposes a new high-temperature superconductor (HTS) modular flux-switching linear machine for rail transit, in which the armature windings and HTS field windings are placed on the short mover, while the long stator is only made of segmented low-cost iron. The key is to adopt a modular mover consisting of three separate phase modules whose positions are mutually 120° electrical degrees apart to greatly offset the cogging force for suppressing the thrust force ripple, accompanied with the features of high-fault tolerance. Also, the HTS excitation can produce stronger magnetic field than permanent magnet excitation to obtain a high force density; meanwhile, it easily regulates the air-gap flux density for achieving flexible high-speed constant-power operation. The operation principle and general design method of the proposed machine with concerning the HTS-excitation pattern are described in details. By using the finite element analysis, the machine performances are comparatively analysed with its counterpart without using modular mover to verify its validity. The results show that the proposed machine can offer more sinusoidal back electromotive force, better fault tolerance, higher thrust force and smaller force ripple.