A new transformerless inverter for grid connected photovoltaic system with low leakage current

Transformer-less inverters are more attractive for grid-tied photovoltaic (PV) system due to its higher efficiency and lower cost. But unfortunately, a leakage current flows through the system. So transformer-less PV inverter have to be tackled carefully. In this paper, a new transformerless PV inverter topology with low leakage current has been proposed. Proposed circuit structure and detail operation principle are presented in this paper. One additional switch with conventional full H-Bridge and a diode clamping branch make sure the disconnection of PV module from the grid at the freewheeling mode and clamp the short circuited output voltage at the half of DC input voltage. Therefore, the common mode (CM) leakage current is minimized. The relationship between H5 topology and proposed topology has been analyzed in this paper. The proposed inverter topology is simulated by MATLAB / Simulink software to validate the accuracy of the theoretical analysis. Finally, a 1kW prototype has been built and tested.