High efficiency resonant converter based on MCT

The trend to reduce the weight and size of power converters resulted in an increase of switching frequency. The standard power device for medium and high power applications is the IGBT. Due to techniques to decrease switching losses, the space and weight limitation of modern converters are conduction losses. When switching losses are reduced, a further increase of efficiency with all its advantages is possible by the use of new power devices like MCTs (MOS controlled thyristors). The bad hardswitching behavior of the MCT practically eliminates the possibility of using it in a conventional high-frequency converter. All of the advantages of the MCT can be used in zero-current switching topologies (zero turn-on and off, ZCS). The paper presents an off-line (520 V DC-15 kW) resonant converter based on MCTs, operating at 100 kHz. A novel, advanced series-resonant converter topology with ZCS is also presented. It utilizes the advantages of low conduction losses of the MCT, promises eliminating turn-off losses and highly reducing turn-on losses. The full load efficiency of the converter is better than 98%. Design, simulation and practical results are discussed