Experimental Study on Transformerless Grid-Connected PV Inverter

This thesis investigates transformerless grid-connected photovoltaic (PV) inverters, focusing on efficiency, leakage current reduction, and reactive power control. Transformerless inverters offer higher efficiency, lower cost, and compact size but suffer from leakage currents that impact total harmonic distortion (THD) and electromagnetic interference. Various inverter topologies, including H7, H8, and NPC-based designs, are analyzed for their performance in terms of common-mode voltage (CMV), power losses, and compliance with IEEE-1547 standards. A novel modulation strategy is proposed to mitigate leakage current while enhancing reactive power capability and low voltage ride-through (LVRT) performance. The study introduces an improved CMV clamped topology that eliminates the need for extra filters, reducing cost and complexity. Simulation and experimental results validate the effectiveness of the proposed techniques, demonstrating enhanced inverter performance. This research contributes to the development of next-generation, efficient, and reliable transformerless PV inverters for grid applications.