Interleaved soft-switching coupled-buck converter with active-clamp circuits

This paper presents a coupled-buck converter with active-clamp circuits. The active switches in the converter can sustain a long enough duty cycle while it operates with a high step-down voltage ratio, reducing current stress significantly. In the converter, the active-clamp circuits provided can have benefits of recycling the leakage energy, while minimum ringing voltage is across the active switches. Moreover, since both main and auxiliary switches can be turned on with zero-voltage switching (ZVS), switching loss can be reduced and conversion efficiency therefore can be improved significantly. A 240 W prototype of the proposed buck converter was built and experimental results have shown that efficiency can reach as high as 89%. It is relatively attractive for applications to hybrid electric vehicle on-board chargers.