Power losses minimization for modular multilevel converters with second-order and fourth-order harmonic circulating current injection

摘要

Modular multilevel converters (MMCs) are regarded as promising topologies in medium/high-voltage and high-power applications. The reduction of power losses is an important issue for MMCs. This paper proposes a power loss minimization control (PLMC) by injecting optimal second- and fourth-order harmonic circulating current into the arm current of MMCs. The proposed control can further reduce the power loss in comparison with the conventional control by only injecting the second-order harmonic circulating current. In addition, the proposed control not only reduces the peak value of the arm current, but also improves the reliability of MMCs. Simulation with the PSCAD/EMTDC and experiment with 1-kW MMC prototype are also conducted and their results confirm the validity of the proposed PLMC for MMCs.