1007

Suspension electromagnet (SEM) is the energy conversion device of the low-speed maglev train. The system adjusts the winding current by the chopper to change the electromagnetic force to realize the contactless operation between the train and the track. The SEM winding is equivalent to a time-varying inductance, and the parasitic capacitance of the winding affects the transient performance of the chopper. This paper proposes an analytical method for calculating the inrush current of the winding. Firstly, the functional expression of the winding terminal voltage is derived by Fourier transform. Then, the SEM winding is equivalent to a black box impedance network composed of inductances, resistances, and capacitances. Finally, the transient response expression of the winding terminal inrush current is deduced according to the circuit superposition theorem. The analysis results show that the inrush current at the moment of chopper switching is the superposition result of the current components with different frequencies through the equivalent series resonant circuit. Finally, the results of the simulation and experiment show the correctness of the proposed method.