Design and Implementation of a Bidirectional DC-DC Forward/Flyback Converter with Leakage Energy Recycled

A bidirectional interleaved forward-flyback DC-DC converter with leakage energy recycled is proposed in this paper. The proposed converter uses two transformers to reduce the current stress on the power components to reduce the conduction loss and improve the efficiency. When the proposed converter is operated in the step-up mode, the voltage across switches is clamped at the input voltage, and the leakage energy is recycled to the voltage source. When the proposed converter is operated in the step-down mode, the voltage of switches is clamped at the input voltage, and the leakage energy is recycled to the clamping capacitor or the voltage source. As the proposed converter is based on flyback converter, it is characterized with simple structure. Since the leakage inductance energy is recycled, the conversion efficiency is improved compared to conventional flyback converter. Finally, a laboratory prototype circuit with 200 V/24 V and output power 500 W is implemented to verify the feasibility of the proposed converter. The highest efficiency in the step-up and step-down stage is 92.3% and 95.5% respectively.