A Soft-Switching Synchronous Rectification Noninverting Buck–Boost Converter With a New Auxiliary Circuit

Abstract

In this article, a new soft-switching auxiliary circuit structure for the synchronous rectification noninverting buck-boost converter (NIBBC) is proposed. This new auxiliary circuit, which contains a fully coupled inductor (or a transformer), a snubber inductor, a capacitor, and a power diode, will provide zero voltage switching (ZVS) turn-ON conditions for all power transistors of the proposed NIBBC. In addition, waveform ripples in the auxiliary circuit of the output side are reduced, and then the output current ripple is also reduced. Meanwhile, the current across the main inductor is not affected by the auxiliary circuit. In order to analyze the proposed NIBBC, operating principles, soft-switching implementation conditions, and main characteristics of the proposed NIBBC are presented in this article. Finally through building a 400-W experimental prototype, key waveforms and measuring efficiency curves are obtained. Experiment result shows that all transistors of the new NIBBC operate under ZVS conditions. The efficiency of the proposed NIBBC is improved by comparing to the triangular current mode soft-switching NIBBC.