Bidirectional Single Power-Conversion DC–AC Converter With Noncomplementary Active-Clamp Circuits

Abstract

This paper presents a bidirectional single power-conversion dc–ac converter with noncomplementary active-clamp circuits. The proposed converter comprises a bidirectional flyback converter and an unfolding bridge. In order to interface the grid with a low-voltage energy storage through only single power-conversion, the bidirectional flyback converter transforms the low voltage directly into the folded grid voltage and regulates the folded grid current. The proposed converter adopts noncomplementary operation strategy for the active-clamp circuits. By using this strategy, the bidirectional flyback converter not only avoids the voltage spike but also minimizes the power losses by the circulating energy. Thus, with single power-conversion and noncomplementary active-clamp circuits, the proposed converter obtains high power efficiency. To facilitate the bidirectional single power-conversion, a novel control algorithm is developed. With this control algorithm, the proposed converter ensures high grid power quality and seamless mode transition. The proposed bidirectional dc–ac converter is theoretically analyzed in detail. The experimental results based on a 250-W prototype are provided to evaluate its performance.