Investigation on High Temperature Superconducting Linear Flux-Switching Motors with Different Mover and Stator Pole Pitch Ratios for Urban Railway Transit System

Linear Induction Motors (LIMs) are popular as driving motors in urban railway transit systems due to their simple and robust stator structures. However, the efficiency and power factor of LIM are lowered because of its eddy effect. As a promising alternative, Linear Flux Switching Permanent Magnet (LFSPM) motor offers high electromagnetic performance while keeping its stator simple. Despite these merits, the adoption of Permanent Magnets (PMs) of LFSPM motors influences their flux-weakening ability, thus leading to narrow speed range. To solve this problem, it is feasible to use High Temperature Superconducting (HTS) coils to replace PMs, forming HTS Linear Flix Switching Motor (HTS-LFSM). Among various parameters that influence the performance of HTS-LFSM, ratio of primary and secondary pole pitches is a leading parameter. Aim at investigating the relationship between pole pitch ratios and electromagnetic performance, different typical pole pitch ratios are compared against each other based on several common principles. The merits and drawbacks are analyzed with the help of Finite Element Method (FEM), and some conclusions are drawn.