A Novel Soft-Switching Full-Bridge Converter

Inserting an auxiliary switch to the conventional hard-switch full-bridge topology, a novel soft-switching full-bridge converter is proposed. Instead of the main switches, the auxiliary switch is pulse-width modulated to regulate the output voltage and soft-switching operation of the main switches can be easily achieved over full line and load ranges. Consequently, the reduced switching losses can be compensated for the auxiliary switch's losses and its efficiency approximates to that of the phase-shift full-bridge converter. It makes the proposed converter to be an alternative approach for high frequency high efficiency power conversion applications. In addition to the circuit analysis and operation principle, a 100 kHz, 300-400 V input and a 12 V, 300 W output prototype is implemented to demonstrate its feasibility.