Soft switching resonant converter with flying capacitor and two series half-bridge legs

A new soft switching resonant converter is presented in this study to reduce the switching losses on power metal oxide semiconductor field effect transistors (MOSFETs) and overcome the reverse recovery losses on rectifier diodes. Two half-bridge legs connected in series and two split capacitors are adopted to limit the voltage stress of each MOSFET at half-input voltage and to reduce the current rating of transformer windings and passive components at output side. A flying capacitor is connected between two half-bridge legs in order to automatically balance two input capacitor voltages. Therefore MOSFETs with low-voltage stress can be used at high-input voltage applications. The resonant converter is adopted in each half-bridge circuit to reduce the switching losses of active devices. Finally, experiments based on a laboratory prototype are provided to verify the circuit performance.