An improved three-phase transformerless photovoltaic inverter with reduced leakage currents

Without utilizing zero vectors, reduced common-mode voltage pulsewidth modulation (RCMV-PWM) have been proposed to reduce the common-mode voltage (CMV) and the leakage current in three-phase transformerless photovoltaic (PV) inverter. Nevertheless, the elimination of the zero vectors from RCMV-PWM methods have degraded the overall performance of the PV inverters such as cost, voltage linearity, dc-link current ripples and harmonic distortion. In order to solve these issues, H7 inverter with modified discontinuous pulsewidth modulation (MDPWM) is proposed recently. The leakage current is reduced without sacrificing the performance of the PV inverter. In this paper, a simple three-phase inverter topology with corresponding modulation technique is proposed. It is proven that the leakage current is reduced to comply with the standard requirement without sacrificing the performance of the PV inverter. The analysis and the performance are verified via simulation results.