Leakage Current Elimination of Grid-Connected PV Panels Using an Improved Non-Isolated DC-AC Heric Converter

In this paper, an improved non-isolated DC-AC HERIC converter is presented to eliminate the leakage current of grid-connected PV panels. The improved topology comprises of high voltage gain four-output boost converter and a nine-level HERIC converter at the output side. The high voltage gain boost converter can provide equal voltage levels for used nine-level HERIC converter considering maximum power point tracking. The nine-level converter can provide nine-stepped voltage waveform at the output voltage waveform. In the proposed transformerless structure, there are parasitic capacitors between grid and PV panel which leads to the leakage current flowing through parasitic capacitors to the system. It causes safety problem, injection of harmonic current into the grid, increasing losses, and efficiency reduction. To eliminate the leakage current of proposed topology, the HERIC topology is used at the output side. In order to control the current of nine-level HERIC converter, model predictive control method is utilized. To confirm the operation of presented structure and theoretical analysis, PSCAD/EMTDC software is used.