Model Predictive PI Circulating Current Control for Modular Multilevel Converter

Significant circulating currents in the modular multilevel converter (MMC) increase system losses and complicate heat-sink design. Conventional PI PR controllers can achieve steady-state error adjustment, but are sensitive to parameter changes model uncertainty, heavily relying on coordinate transformations careful design of parameters. Model predictive control (MPC) has characteristics simple design, good robustness, excellent dynamic response; however, it encountered complexity adjusting weighting factors. This paper proposed current proportional integral (MPPIC) method abc reference frame. hybrid solution utilized traditional algorithm combine advantages nonlinear linear control. Compared with existing suppression methods, this avoided complex mathematical operations a selection weight coefficients, was easy implement, effectively suppress under different modulation ratios. Simulations were conducted MATLAB/Simulink verify effectiveness strategy. MPPIC not only distinctly currents, also reduce overall voltage fluctuation sub-modules capacitors ratios, had almost no any adverse effect performance MMC.