This article presents a new MOS gate controlled thyristor-single-gate emitter controlled thyristor (SECT). Its operation is verified by two-dimensional numerical simulations and the operation mechanisms are analyzed. Simulation results obtained on a 2500 V SECT show that the SECT has an excellent high voltage current saturation capability and much wider FBSOA and RBSOA than those of the IGBT and the DC-EST, while at the same time offering lower conduction and switching losses than those of the IGBT.