Non-isolation Soft-switching Buck Converter with Tapped-Inductor for Wide-input Extreme Step-down applications

In this paper, a new zero-voltage switching (ZVS) buck converter with a tapped-inductor is proposed. This converter improves the conventional tapped inductor critical conduction mode (CRM) buck converters that have the ZVS operation range determined by the tapped-inductor turn ratios. It includes another soft switching range extension method, the current injection (CI) method, which gives an additional design freedom for the selection of the turn-ratios and enables the optimal design of the winding ratio of the tapped-inductor so that both the switching loss and the conduction loss may be minimized. This soft-switching buck converter is suitable for extremely low step-down ratio applications. The principle of the proposed scheme, analysis of the operation, and design guidelines are included. Finally, the experimental result of the 100 W prototype DC/DC converter is given for hardware verification