A study on MMC model and its current control strategies

Modular multilevel is a new type of topological structure. The voltage source converter that adopts this type is named as Modular Multilevel Converter-MMC. In this paper, the operating principle of MMC is analysed and the mathematical model based on switching function is presented, and then average value model of MMC in DQ coordinates is deduced in order to meet the requirements of MMC control system design. The non-linear current decoupling control strategy is proposed. Computer simulation is performed to verify the MMC model and the efficiency of current control strategy. In addition, the simulation results show good performance and the quick response ability of the proposed controller.