Neutral Point Clamped Non-Isolated Three Phase Grid-Integrated PV Inverter Topologies for Leakage Current Reduction

This study analyses neutral point clamped-based non-isolated grid-connected inverter topologies. Transformerless inverters are widely used because of their higher efficiency, lower cost, and compatibility with grid integration. The main drawback of the non-isolation inverter is maintaining the Common Mode Voltage (CMV), eliminating the Leakage Current (LC) and galvanic isolation during the grid fault condition. Galvanic isolation and elimination of leakage current in non-isolated inverter topologies mainly depend on inverter configuration and pulse width modulation techniques used in the inverter topologies. Many single-phase non-isolated inverter topologies are configured and analysed based on these issues. However, only a few studies have been conducted on three-phase non-isolated inverter configurations. Hence, this paper examines different three-phase non-isolated inverter topologies based on neutral point clamping with modified discontinuous pulse width modulation technique on CMV, LC reduction, current total harmonic distortion, conduction losses and efficiency of the inverter structures. Simulations are carried out in MATLAB/Simulink for proposed inverter topologies, and experimental analysis has been done for validation.