Soft-Switching High Step-Up/Down Converter Using Coupled Inductors With Minimum Number of Components

Abstract

This article presents a soft-switching buck–boost converter with high step-up/down conversion ratio. The popular coupled inductors method is employed to achieve high step-up/down gain conversion. Moreover, a simple auxiliary circuit, including a small capacitor, active switch, and an extra winding on the coupled inductors, is utilized to provide soft-switching condition for the main switches in both operating states. This simple auxiliary circuit is a proper substitute for two essential active clamp circuits required in bidirectional converters with coupled inductors. Also, the added auxiliary winding is employed in the power flow path to increase the step-up/down voltage gain. All switches have zero current switching (ZCS) turn-on and zero voltage ZCS (ZVZCS) turn-off performance, which eliminates the reverse recovery problem of switches body diodes and improves converter efficiency. A 300-W prototype converter with 48–380\xa0V conversion ratio is realized to confirm the validity of theoretical analysis and the operation of the proposed converter.