Switchless Power Decoupling and Switchless Leakage Current Elimination in Grid-Tied Inverters

This paper presents a grid-tied single-phase transformerless inverter that eliminates simultaneously the leakage current issue and the double grid frequency power pulsation without additional active circuitry. The control scheme considers the full bridge inverter as two buck converters that are connected differentially with the utility grid. Thus, controlling the two converters modulation indices assures that the double frequency power pulsation is decoupled at the AC-side of the inverter and the current injected into the grid is sinusoidal with unity power factor. In other words, this configuration would improve the system reliability since the power decoupling allows the usage of film capacitors at the DC-side and the elimination of the leakage current improves the system safety.