Implementation of the ZVS converter with synchronous rectifier

The paper presents the system analysis and circuit design of a half-bridge zero-voltage-switching (ZVS) flyback converter with synchronous rectifier. The leakage inductance and output capacitance of active switches are used to realise ZVS operation during the transition state between two switches. The switching power loss of active switches can be reduced to a minimum due to the ZVS operation such that the high-efficiency circuit can be achieved. The circuit-operation principle, mathematical analysis and design example of a half-bridge ZVS flyback converter with synchronous rectifier are explained and analysed. The synchronous rectifier is used at the transformer-secondary side to reduce further the conduction loss and to increase the circuit efficiency. Finally the experimental results from a 24 V/7 A output load with 100 kHz switching-frequency prototype circuit are provided to verify the theoretical analysis.