Predictive Control of Modular Multilevel Converters: Adaptive Hybrid Framework for Circulating Current and Capacitor Voltage Fluctuation Suppression

Modular multilevel converters (MMCs) are widely used in voltage-sourced, converter-based high-voltage DC systems due to their modular design, scalability, and fault tolerance capabilities. In MMCs, multi-variable control objectives can be employed by using model predictive (MPC) its fast dynamic response ease of implementation. Nonetheless, conventional MPC techniques for MMCs have shortcomings, including high computational requirements, poor circulating current, capacitor voltage fluctuation suppression. First, this study proposes an adaptive technique that adapts the number candidate combinations steady transient states, significantly reducing burden. Second, improved hybrid combination with a proportional-resonance (PR) controller enhances current suppression performance. According phase difference between voltage, suppressed at different times changing reference PR controller. The switching frequency reduced controller’s output adjust input submodule instead duty cycle. proposed were validated simulations experimental case studies three-phase grid-connected MMC.