Efficient Transformerless MOSFET Inverter for Grid-Tied Photovoltaic System

Abstract: The grid tied photovoltaic system suffers a great loss because the perormance of the transformer present in the inverter. The cost of the transformr is high and the maintaince cost is also high.Therefore transformerless inverter are widely used in grid tied photovoltaic system,due to the benefits of achieving high efficiency and low cost. The sinusoidal pulse width modulation of full bridge transformerless inverters can achieve high effeciency by using metal oxide semiconductor field effect transistor. Various topology has been implemented for transformerless inverter, but in that there is a problem of losse and reverse recovery characteristics. In our paper we are going to implement the centre tapped H bridge transformerless inverter topology for grid tied photovoltaic system to avoid the losses and leakage current. A clamped branch is added in the transformerless inverter. The added clamping branch clamps the freewheeling voltage at the freewheeling period. As the common mode voltage is kept constant for the whole grid period that reduce the leakage current. The splitting structure of inductor at the region of grid side avoids reverse recovery voltage and this improves the effeciency of the system. The detailed analysis of our topology with the operational modes, leakage current analysis and design consideration were implemented.

Keywords: Transformerless; Photovoltaic; Grid connected; Efficiency.