A new technique to achieve zero voltage switching in resonant reset single switch forward converter

Zero voltage switching (ZVS) or soft switching is gaining prominence for a variety of reasons. The benefits and the limitations of ZVS are well documented in the literature. Though the true ZVS is possible in full bridge converters, special design considerations need to be addressed in forward converters to achieve true ZVS. In this paper a new technique is proposed to achieve true ZVS without the loss of duty cycle or increased primary circulating currents in a single switch forward converter. Resonant reset technique is adapted for the transformer reset and the same is extended to achieve ZVS .This principle is demonstrated by developing a practical 240 watts DC to DC converter operating at 250 KHz and from a high voltage 400 V DC bus. The measured data depict an improvement in the converter efficiency.