Buck‐boost‐flyback integrated converter with single switch to achieve high voltage gain for PV or fuel‐cell applications

Abstract

This study presents a buck-boost-flyback integrated converter (BBFIC), which can step up the voltage of photovoltaic (PV) module or fuel cell to a much higher level for grid-tied applications. The converter combines two buck-boost converters and one flyback converter into a single-stage structure with single power switch. In the power stage, an inductor and a coupled inductor are adopted to feature buck-boost and flyback behaviours, and three capacitors are connected in series to stack up output voltage. Even though it possesses the characteristics of buck-boost and flyback converters, the problem of reversed voltage polarity is avoided and the energy stored in leakage inductor can be recycled without additional active clamp circuits. The structure of BBFIC can be easily expanded to obtain an extra-high voltage gain by stacking buck-boost cells or flyback cells. Voltage gain derivation and theoretical analysis are detailed in this study. Simulations and practical results measured from a prototype have validated the proposed BBFIC.