Leakage current reduction for transformerless three-level T-Type photovoltaic grid-connected inverter

This paper proposed the common mode model of three-level T-Type inverter. Then a kind of improved LCL filter, where the capacitor common point was linked to the DC neutral point, was used to eliminate the leakage current. However, this improved LCL filter changes the mechanism of the neutral-point potential. Traditional algorithms, such as the distribution factor algorithm, are no longer applicable. In order to control the neutral-point potential, a new general distribution factor algorithm was proposed in this paper. Experimental results demonstrate the availability and correctness of the theoretical analysis and algorithm.