Predictive Control Using Virtual Voltage Vectors for Three-Level Neutral-Point Clamped Inverters With Constant Common-Mode Voltage

There is a substantial problem caused by the common-mode voltage (CMV) that is generated by PWM approaches. CMV fluctuations are responsible for the generation of harmonics with high-frequency range and leakage current flow in transformer-less photovoltaic systems. In this paper, a model predictive current control (MPCC) method employing virtual voltage vectors (VVVs) to solve aforementioned the problem in three-phase three-level neutral-point clamped (3P3L-NPC) inverters. In order to reduce CMV fluctuations, only some switching vectors are used, in which case the number of switching states is reduced and the THD of the output current of the 3P3L-NPC inverter increases. The increase in the functional area of the 3P3L-NPC inverters and the decrease in the THD of the output current has a direct relationship with the increase in the number of voltage vectors of the switching, which is realized using virtual voltage vectors. The simulation of a three-level NPC inverter is used to assess the suggested theory’s outcomes.