From H4, H5 to H6 —Standardization of full-bridge single phase photovoltaic inverter topologies without ground leakage current issue

Abstract

Leakage current (common mode current) appears through the stray capacitance between the PV array and the grid in transformer-less grid-connected photovoltaic (PV) inverters. The seriousness of the effect has been an area of concern over the past years. Detailed review, investigation, classification and evaluation of full-bridge (H4) single phase PV inverter topologies without this problem are presented in this paper, such as H4, H5 and H6 circuits. Based on the analysis and comparison, some novel H6 topologies with high efficiency and ground leakage current issue eliminated are also proposed, which are also selected as candidate topologies for the standardized inverter topology. Simulation and experimental results are provided for the topology verification, 98.5%maximum efficiency of the prototype is achieved.