Model Predictive Control of Modular Multilevel Converters with Independent Arm-Balancing Control

The model predictive control (MPC) for modular multilevel converter (MMC) has drawn attention among researchers in recent years due to its straightforward implementation, ability to control multiple objectives in a single cost functions, and excellent dynamics response. The AC-side current, circulating current and arm voltage are the three key control objectives for MMC. In most of the existing papers, the three objectives are direct added into a single cost function without considering the couplings within them. The circulating current and arm voltage depend on each other, so they are hard be controlled to the reference value at the same time in a single cost function. In this paper, a MPC of MMC with an independent arm-balancing control is proposed. The proposed strategy decouples the circulating current and arm voltage with an arm-balancing control. The performance of the proposed strategy for a 21-level MMC is evaluated based on the simulation studies.