Improved Zero Voltage and Zero Current Switching Full Bridge PWM Converter with Active Clamp

An improved zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to solve the problems of the previously presented ZVZCS-FB-PWM converter with secondary active clamp such as narrow ZVS range of leading-leg switches [6]. By adding an auxiliary inductor in between the leading-leg and separated input source voltages, the ZVS of leading leg switches can be extended to the whole line and load ranges, which eliminates unwanted hard switching of clamp switch and simplifies its control. The principle of operation is explained and analyzed. The features and design considerations of the proposed converter are also illustrated and verified on a 3 kW, 100 kHz IGBT based experimental circuit.