Transformerless Three Level Diode Clamped Inverter for Single Phase Grid Connected Photovoltaic System

The traditional grid-connected PV inverter includes either a line frequency or a high frequency transformer between the inverter and grid. The transformer provides galvanic isolation between the grid and the PV panels. In order to increase the efficiency, to reduce the size and cost, the effective solution is to remove the isolation transformer. It leads to appearance of common mode (CM) ground leakage current due to parasitic capacitance between the PV panels and the ground. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in transformerless PV system, split-inductor neutral point clamped three level inverter (SI-NPCTLI) with neutral line of the grid connected to the midpoint of capacitor’s bridge leg of the inverter is proposed in this paper. The simulation result of the proposed topology using MATLAB/SIMULINK is presented.