Using Virtual Voltage Vectors in Predictive Control of Three-Phase Inverters for Fixing Common-Mode Voltage

In transformerless photovoltaic systems, common-mode voltage (CMV) fluctuations causes high-frequency harmonics, and leakage current flow. This paper proposes a strategy for finite control set model predictive control (FCS-MPC) with virtual voltage vectors (VVVs) to fix this issue. Only odd vectors are utilized to reduce CMV fluctuations and total harmonic distortion of the output current load. Using the proposed method, the fluctuations and high-frequency harmonics of the common-mode voltage are reduced. Also, using the virtual voltage vectors in the proposed method, the possible number of switching stats increases. This leads to the reduction of discrepancy between the measured and reference currents in cost function and also THD output current. The results of the proposed theory are evaluated through the simulation of a two-level voltage source inverter.