A Practical Method to Eliminate the Common Mode Current of 3-level Active Neutral Point Clamped Inverters with Uncertain Parasitic Capacitance of Photovoltaic Panels

A feedback inductor can be added to suppress the common mode (CM) current for the 3-level neutral point clamped inverter. However, the method works well based on a before known parasitic capacitance of the photovoltaic (PV) panel C
_PV
, which is not practical for the real PV plant. Further, if the C
_PV
is large, the feedback inductor can be too small to implement. This paper proposes a practical method to eliminate the CM current of the 3-level active neutral point clamped (3L-ANPC) inverters with uncertain parasitic capacitance of PV panels. Firstly, the circuit model is built for the CM current for the 3L-ANPC inverters. Then the practical method is proposed that is just by adding an CM inductor and the principle is explained. Further, the design method is addressed. In the end, the method is validated by the simulated and experimental results.