Filter-Clamped Two-Level Three-Phase Transformerless Grid-Connected Photovoltaic Inverter for Leakage Current Reduction

Transformerless Photovoltaic (PV) grid-connected systems benefit from improved cost, size, weight, and efficiency compared to the isolated alternatives. A drawback of the trasnsformerless PV inverters is the leakage current that flows through the parasitic capacitance formed between the PV cells and panel metal frame connected to the earth. The leakage current increases the current harmonics injected into the utility grid, the radiated and conducted electromagnetic interference (EMI), and losses. In this paper, a two-stage three-phase Filter-Clamped (FC) transformerless PV system is employed that reduces the leakage current and output current THD compared to the conventional three-phase inverters. Unlike other transformerless PV inverters, the FC inverter does not require any additional component. The FC transformerless PV inverter is analyzed mathematically and its excellence is compared to the conventional three-phase inverter through simulation results.