The Efficiency Analysis for Three-level Grid-connected Photovoltaic Inverters

The grid-connected photovoltaic (PV) systems are an important part of renewable energy sources and their effect is getting more and more extensive. To improve the efficiency, small volume, and low prices of the PV systems, many kinds of new inverter topologies have been proposed to avoid using a grid isolation transformer, and the traditional three-level neutral-point-clamped (NPC) topology structure and T topology structure are presented and in-depth analyzed in this paper. Relative to conventional NPC topology, the T topology with fewer switching devices than before when producing the same number of output levels, which simplifies circuit and saves costs. Efficiency analysis results show that T topology have high efficiency, lower leakage current and EMI.