A Novel ZCS Full-Bridge PWM Converter with Simple Auxiliary Circuits

Classical full-bridge converters with zero-voltage and zero-current-switching (ZVZCS) mainly achieve the zero-voltage-switching (ZVS) in leading leg and the zero-current-switching (ZCS) in lagging leg. However, when IGBTs are used in high-voltage high-power applications, the great turn-off loss of the leading leg cannot be ignored due to the current tailing. Therefore, the conditions of ZCS for PWM full-bridge converters are analyzed in this paper. And a general strategy which embraces topology design and control method is presented to realize the ZCS for main switches. On this basis, a novel ZCS method with simple auxiliary circuit for PWM full-bridge converter is proposed and tested. This proposed method can realize the ZCS both for full-bridge converter switches and the auxiliary switch, thus high efficiency can be achieved. Specific operation principle and design procedure of this proposed ZCS method are presented. Finally, the theoretical analysis of proposed method is verified by a 600 V/2.5kW experimental prototype.