| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系碩士班 === 95 === This thesis presents the steady-state analysis and implementation of a ZVS forward-flyback converter with parallel-connected current-doubler rectifier. The voltage spike and switching losses of the switch devices are reduced by an active clamp circuit which consists a clamp capacitor and an auxiliary switch. The zero-voltage switching (ZVS) turn-on of the switch devices is due to the resonance based on the leakage inductor of the transformer and the parasitic capacitor of the switch devices. Since the switch devices turn on with zero voltage, the efficiency of the converter can be increased. The parallel-connected current-doubler rectifier is used at the converter secondary side in order to reduce the current stress of the transformer-secondary winding. In addition, the benefit of the current-doubler rectifier is ripple cancellation seen by the output filter capacitor. As a result, the output filter element value or capacity can be decreased. Finally, experimental results are obtained from a 150KHz 5V/40A prototype circuit which is used to show the validity of the analytic procedures.
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