A Novel MMC Circulation Suppression Control Strategy under Asymmetric Bridge Arm

Starting from the basic theory of Modular Multilevel Converter (MMC), this paper analyzes the basic structure of MMC and provides an analysis and explanation of the bridge arm circulating current and its suppression strategies. In practical applications, there is inevitably an asymmetry in the parameters of the upper and lower bridge arms of MMC, which makes the circulating current components more complex, with a DC component appearing in the circulation. Corresponding circulating current suppression strategies are proposed for both symmetric and asymmetric bridge arm situations, and simulation models have achieved good results in suppressing circulating currents.