Inherent clamp flyback-buck converter with winding cross-coupled inductors

An isolated interleaved buck-type converter is deduced by inserting a third winding of the coupled inductor to each phase of the interleaved flyback converter. By making some topology modifications and adding one small clamp capacitor, the existed power switches of the derived flyback-buck converter can serve as the clamp switches for the interleaved phase to absorb the leakage energy of the coupled inductor and to reduce the switch turn-off voltage stress, which simplifies the circuit configuration and improves the circuit reliability. Furthermore, the current falling rate of the output diodes is limited by the leakage inductance to alleviate the output diode reverse-recovery problem. Finally, a 160-W 200-V-input 15-V-output prototype is built and tested to verify the improved performance of the proposed converter.