Simple zero voltage switching full-bridge DC bus converters

A simple method to achieve zero voltage switching (ZVS) In a 50% duty cycle full-bridge DC bus converter is presented. The ZVS is obtained by increasing the transformer magnetizing current. During the small dead time between conductions of the two bridge legs, the increased magnetizing current supports the output inductor current, and resonates with MOSFET output capacitance, resulting in ZVS operation. By adopting the ZVS operation, the body diode conduction and voltage spikes across the secondary synchronous rectifiers are eliminated, full load efficiency is increased, and transformer flux balance is guaranteed. ZVS advantages and tradeoffs are demonstrated with a practical 240 W DC bus converter