A novel dual topology modes cascaded neutral-point-clamped gird-connected inverter

This paper proposes a dual topology modes neutral-point-clamped grid-connected inverter (DTM-NPCI) suitable for the photovoltaic generation system. Two bidirectional power switches are plugged into the single-phase cascaded NPC inverter (CNPCI) to connect the positive poles and negative poles of the two NPC inverters (NPCI) respectively to achieve the switching between the CNPCI and the single NPCI. The system works in CNPCI or NPCI according to the actual output power and voltage of the PV array to achieve a wide operational range and high European efficiency. Taking that the grid current THD meets the specific grid-connected standard in the entire operational range as the requirement, the operational ranges of the two topology modes are determined. The experimental results of the proposed DTM-NPCI are shown to validate the accuracy and feasibility.