In the field of ultra-high-speed maglev trains, the electromagnetic suspension system (EMS) based on the constant conductive excitation linear synchronous motor is a feasible technical solution. The EMS linear motor comprises multiple long stator segments where the activated segment is supplied by square-wave voltage under high-speed operating conditions. To investigate the electromagnetic performance of the motor, a small-scale unit model considering the circuit parameters of the stator segment and the traction power system needs to be built. In addition, the long transient time in the simulation process due to the voltage supply causes inconvenience. In this article, a simulation model of a unit motor is established based on the power supply system. According to the electromagnetic force requirements and the converter’s rated parameters, the appropriate system parameters are selected for the unit model. Then, an accelerated calculation method combining the finite element method (FEM) and recursive mathematical model is proposed to shorten the calculation time of the transient process. Finally, by comparing with the direct calculation method based on the finite element method (D-FEM), the rapidity and accuracy of the proposed method are verified.