Improved SEM Current Ringing Suppressor for Maglev Trains

Abstract

In electromagnetic suspension (EMS) systems, the air gap between the suspension electromagnet (SEM) and steel track is adjusted by changing the electromagnetic attraction force, which is accomplished by controlling the maglev chopper (MC). When switching the power electronic devices of the MC, SEM current ringing tends to occur, which is harmful to the whole EMS system. A conventional current ringing suppressor (CRS) deteriorates the SEM port voltage ringing, which may accelerate the aging process of SEM insulation or even directly result in a breakdown fault. Herein, to explore the generation mechanism of SEM current ringing, a third-order equivalent circuit model of the suspension electromagnet-maglev chopper (SEM-MC) system is established by using the field-circuit coupling analysis technique. A series of simulations and experiments have been undertaken to verify the validity of the built circuit model, and the deviation between the simulation and experimental results is acceptable. As the influencing factors of SEM current ringing are analyzed based on this third-order equivalent circuit model, an improved CRS, i.e., hybrid inductor-resistor CRS, is proposed to avoid deteriorating the SEM port voltage ringing and protect the SEM insulation. Finally, the feasibility of the proposed hybrid inductor-resistor CRS is verified by corresponding experiments.