Improving Efficiency of an Asymmetrical Half-Bridge PWM Converter with Synchronous Rectification by a Modified Design Process

Abstract

High efficiency calls for soft switching and high frequency converters. Correctly designed asymmetric half-bridge PWM converters employing ZVS represent an attractive candidate. For low output voltage applications, synchronous rectification should allow efficient operation. However, since simple replacement shows promising results through simulation, a test setup reveals a great discrepancy. Massive oscillations during the turn-off transition of the synchronous rectifier causes enormous losses. Therefore, a second synchronous rectifier design is investigated, which uses an alternative design method. This design confirms the improved efficiency achieved by simulation.