Series Resonant DC-DC Converter with Single-Switch Full-Bridge Boost Rectifier Operating at Fixed Switching Frequency

In this paper, a PWM scheme is proposed for the series resonant converter (SRC) with a full-bridge boost rectifier at the output side. This rectifier is comprised of a switch and three diodes. It was previously presented with a static control switching between the modes of full-bridge and voltage doubler rectifiers. The proposed PWM scheme controls the voltage gain between these two modes arbitrary using the duty cycle of the switch. In addition, SRC is operating at a fixed switching frequency. The proposed PWM scheme forces the resonant current to have a roughly sinusoidal shape in the first half-cycle of the switching period. This could reduce the peak current at turning on/off of the semiconductors. Then, a boosting interval is applied to the rectifier switch, so that the resonant inductor charges similar to the boost converter to boost the input voltage. The primary side semiconductors achieve the zero voltage switching (ZVS) at the turn-on. At the same time, the rectifier diodes achieve zero current switching (ZCS) at the turn-off. Theoretical analysis and a 250 W prototype are provided to prove the feasibility of the proposed scheme. The converter achieves a peak efficiency of 95.9 %.