Abstract:In order to solve excessive inter phase circulating current that caused by modular multilevel converter (MMC) submodule voltage fluctuation, this paper proposes a new type of circulating current suppressor that combines a low-pass filter with multiple quasi-proportional resonant controllers (ZPR) connected in parallel on the basis of designing the voltage equalization of MMC submodules. This paper first introduces the basic topology of MMC and analyzes the relationship between the voltage fluctuation of MMC bridge arm sub module and the circulation of the bridge arm, then proposes the circulation control strategy based on MMC capacitor voltage sharing control, and finally verifies the effectiveness and feasibility of the scheme in Matlab/Simulink. The simulation results show that the fluctuation range of MMC sub module capacitance voltage is small and the circulation of MMC medium and low frequency is small All are within a reasonable range.