Harmonic Modeling of Armature Field of Air-cored Linear Synchronous Motor with Racetrack Coil

High speed Maglev trains assembled with onboard superconducting magnets (SCM) have drawn wide attention in recent years, wherein, the air-cored linear synchronous motor (LSM), served as the power source for propulsion, is a core component. In this paper, a novel equivalent method to deal with irregular distributed currents is proposed and an analytical model of armature magnetic field is established for the air-cored LSM via 3-D magnetic vector potential method. Based on that, the harmonic field suppression mechanism of double-layer winding configuration of the LSM is revealed. Meanwhile, the formulas to calculate the interactive electromagnetic forces from the perspective of armature magnetic field are deduced, therein, the longitudinal end effect of the air-cored LSM has been inherently considered. Finally, both the finite element analysis and experimental results are employed to verify the validity of theoretical predictions. The proposed method can calculate the armature magnetic field distribution with arbitrary coil shape with high accuracy, hence, provide a reliable approach to investigate the electromagnetic force and electromagnetic disturbance from ground coils in electrodynamic suspension (EDS) system.