A soft-switched, full-bridge pulse-width-modulated converter and its variations provide zero-voltage-switching conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this invention achieve ZVS with a substantially reduced duty cycle...http://www.google.com/patents/US6992902?utm_source=gb-gplus-sharePatent US6992902 - Full bridge converter with ZVS via AC feedback
