A new modulation technique to eliminate leakage current in transformerless PV inverter

Abstract

In this paper a new modulation technique is proposed to eliminate the common mode leakage current in transformerless photovoltaic (PV) inverter topology. The proposed modulation technique uses third harmonic injection with multicarrier phase-shifted pulse width modulation. The modulation method is applied to the single-phase full-bridge five-level grid connected PV transformerless inverter topology. The PV based single phase five-level inverter composed of full bridge inverter with additional two switches at the input dc side. This paper also compares the investigation of conventional unipolar and bipolar sinusoidal pulse width modulations for the single-phase full-bridge inverter topology with the proposed modulation technique. The results confirm that the inverter topology provides safer limits for the ground current and low harmonic content in the grid current. Simulation studies are carried out using PSCAD/EMTDC environment which demonstrates the effectiveness of the proposed modulation technique.