Analysis of Characteristics in Linear Synchronous Motor for High-Speed Maglev Trains with Irregular Air-Gap

High-speed maglev trains represent an innovative contactless ground transportation solution to inter-city rapid transit. The propulsion critically depends on linear synchronous motors, whose performance directly determines operational smoothness and safety. The unique decoupled structure of long-stator LSMs causes their air-gap length to be dynamically influenced by both train attitude and track condition. This configuration makes the three-dimensional electromagnetic forces particularly sensitive to these mechanical and geometric parameters. This paper investigates the impact of four operational conditions—sagging of long stator segments, inter-segment gaps, yaw, and transversal offset—on the air gap. Based on FEM, 2D/3D analytical models were established to compute and analyze thrust and levitation force of the long-stator linear synchronous motor, which shows the influence patterns of irregular air-gap on electromagnetic forces. It provides valuable references for the design and control of propulsion system for high-speed maglev trains.