A Novel Control Strategy for Circulating Current Suppression of Modular Multilevel Converter

Modular Multilevel Converter (MMC) is widely used in high-voltage and high-power applications. However, MMC faces challenges like circulating current suppression. This paper proposes a circulating current suppression strategy based on super twisting sliding mode control (SMC) with precise decoupling to suppress the second-order component of circulating current. It incorporates super twisting control algorithm into the traditional SMC structure, which solves the chattering problem in SMC. Besides, the model of circulating current is precisely decoupled by exact feedback linearization method, which improves system's rapidity and anti-interference ability. The validity of the proposed strategy is confirmed by MATLAB/Simulink simulation results.