Grid Filter Reduction of Single-Phase Inverters using 3-Leg Topology

Single-phase grid-connected inverters have been widely used in distribution power systems to regulate the behavior of various distributed energy resources and to support the operation of distribution grids. In a typical single-phase inverter system, the grid filter is used as an essential component in minimizing total harmonics distortion as well as electromagnetic interference in order to satisfy modern grid interconnection standards. However, all these grid filters use passive components and have their performance tradeoffs between their filtering performance and their size and weight criteria. In this paper, a 3-leg inverter topology, which features a switching-based active power filtering technique, is proposed for single-phase grid-connected inverters to perform passive filter reduction so that the power density of the inverter system can be improved. The effectiveness of the proposed topology is verified by theoretical analysis, detailed circuit analysis, and simulation and experimental results on a MATLAB/SIMULINK simulation platform and on a 3-leg inverter prototype.