An Improved Transformerless Inverter Topology for Grid Connected Photovoltaic System

Abstract

Transformerless inverters are gaining importance in grid integration of PV power due to high efficiency, compact size and low cost. Leakage current is the major issue in these inverters which needs to be eliminated. The leakage current depends on common mode voltage (CMV), PV module parasitic capacitances and stray switches junction capacitances. In this paper, an improved common mode voltage clamped transformerless inverter topology has been proposed. Unlike H5 and HERIC topologies, the proposed topology generates constant CMV during both power transfer and freewheeling periods. As a result, leakage current is eliminated. Moreover, the proposed topology is compared with classic full bridge and H5 topologies. The analysis of the proposed topology is carried out in Matlab Simulink. A 2.7 kW grid connected inverter prototype was developed in Matlab Simulink environment.