A single-phase transformer-less inverter with active decoupling

This paper presents a novel inverter topology that is applied to single-phase grid-connected photovoltaic systems. The proposed topology has an active decoupling function, which not only eliminates the double line frequency ripple power in the dc-link but also accepts large voltage ripple across the decoupling capacitor in order to reduce the requirement of the decoupling capacitance. Traditionally, bulky electrolytic capacitors are employed in passive decoupling of power, which limits the system lifespan. The reduction of the decoupling capacitance makes it possible for using long life film capacitors in photovoltaic systems. The simulation results verify the operation of the proposed topology and its control strategy.