Zero-Voltage and Zero-Current-Switching Full-Bridge PWM Converter Using Secondary Active Clamp

A new zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulsewidth modulation (PWM) converter is proposed to improve the performance of the previously presented ZVZCS FB PWM converters. By adding a secondary active clamp and controlling the clamp switch moderately, ZVS (for leading-leg switches) and ZCS (for lagging-leg switches) are achieved without adding any lossy components or the saturable reactor. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high-voltage and high-power (>10 kW) applications. The principle of operation is explained and analyzed. The features and design considerations of the new converter are also illustrated and verified on a 1.8-kW 100-kHz insulated gate bipolar transistor (IGBT)-based experimental circuit.