Long stator linear synchronous motor（LS-LSM） is used to drive high speed maglev train. Change-step is an important operating mode of maglev vehicle. In order to simulate the change-step process, this paper established a simulation system for LS-LSM, the change of motor parameters during the process of step changing is introduced into the mathematical model of LS-LSM to approach the real condition. On this basis, this paper proposed an optimal time to switch current and a method of thrust compensation to reduce the thrust loss. Finally, the correctness of the theoretical analysis is verified by simulation results.

LS-LSM， high speed maglev， change-step， mathematic model