Bidirectional ZVS Buck–Boost Converter With Single Auxiliary Switch and Continuous Current at Low Voltage Source

Abstract

In this article, a bidirectional zero voltage switching buck–boost dc–dc converter with a simple auxiliary circuit is presented. The auxiliary circuit employs only a single switch and a pair of coupled inductors to provide soft switching condition in both power flow directions. Moreover, the soft switching condition is independent of the load variation and duty cycle. Energy storage devices such as batteries and super capacitors are commonly utilized in systems using bidirectional converters as the low voltage source. Batteries require continuous current to prolong their life time and overall system efficiency. The proposed converter has continuous current at low voltage side in both operating modes, unlike the similar converters, which utilize coupled inductors in order to provide soft switching condition. Fully soft switching operation including the zero current switching condition of all diodes at turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> has significantly contributed to the converter overall efficiency. Operating principles, mathematical derivations and the soft switching conditions of the proposed converter are analyzed in both boost and buck operating modes. Furthermore, to confirm the main converter features and the theoretical analysis, a prototype of the proposed converter is implemented at 100 W–100 kHz and the experimental results are presented.