An improved transformerless grid-connected photovoltaic inverter with reduced leakage current and increasing number of output voltage level

Abstract

Transformerless inverters are most preferred for grid connected photovoltaic (PV) generation system due to higher efficiency and lower cost. Low leakage current and high efficiency are two key indexes for transformerless PV grid-connected inverter. Nevertheless, to observe the safety regulations, the leakage current which reduces the power quality and generates electro-magnetic interference in transformerless PV inverter, has to be addressed carefully. In this paper presents a multilevel transformerless single-phase inverter, which is composed of one H-bridge, one bidirectional switch and one damper circuit to reduce the ground leakage current. Comparison of the proposed inverter configuration and the transformerless single-phase inverters is given based on the power circuit component count. Moreover, analysis of the power losses in the power semiconductor switches of the proposed and several existing topology is given. Finally, proposed topology is simulated by MATLAB/ Simulink software to validate the accuracy of the theoretical analysis.