A novel soft-switching bidirectional DC-DC converter with coupled inductors

This paper presents a novel topology for a non-isolated bidirectional dc-dc converter with soft-switching capability, which usually operates at a zero-voltage-switching (ZVS) condition. A non-isolated dc-dc converter combines a buck converter and a backwards boost converter into one circuit, which consists of a half-bridge power switch, an inductor, and capacitors. In order to realize ZVS conditions, the proposed converter utilizes an additional inductor coupled with the main inductor, a small inductor, and auxiliary switches and diodes. Due to ZVS, switching stress on switch components is reduced, and the reverse recovery problem of MOSFET anti-parallel body diodes is also solved. Moreover, the proposed converter can arbitrarily select the operating modes between ZVS and conventional hard-switching, so the converter can obtain the highest efficiency at almost all load ranges. The detailed theoretical analyses in each mode are presented, and a 1kW prototype is also built to verify the principles.