Common Mode Reduction of Transformer less Inverter for Grid Connected PV System

Abstract

Smaller size, lower cost and more efficient transformerless inverter connected for PV system, are highly in demand. If the PV inverter has not galvanic isolation, leakage current will appear and the common mode voltage (CMV) will increase. Because of the lack of isolation, the strong ground currents may appear in system which are depending on the parasitic capacitances to ground. The CMV should be reduced to block adverse events resulting of the leakage current. Furthermore, the loss of switching should be least in order to reach more efficient. In this paper, a modified topology based on the H6 topology is proposed and analyzed.  Performance of the proposed topology is compared to other several topologies using the MATLAB/Simulink. The performances of the pulse width modulation (PWM) topologies are discussed and results are then compared based on CMV and the leakage current. The simulation results show that using diode clamped to dc voltage, leakage current is reduced and generated CMV is approximately constant.