Hierarchical MPC for optimal bidirectional charging of battery modules using modular multilevel converters

This paper presents a hierarchical model predictive control (MPC) strategy for optimal charging and discharging of battery modules in a modular multilevel converter (MMC) system. The proposed two-layer architecture consists of an offline optimization layer and an online predictive control layer. The offline layer determines upper bounds on the number of time slots per load factor that each battery module can be assigned. The online layer utilizes these bounds to regulate module currents online, ensuring correct converter functionality and compliance with the planned energy distribution. This coordinated framework enables state of charge (SoC) balancing, allowing all battery modules to reach their terminal SoC targets while minimizing degradation and improving overall charging efficiency. Simulation results illustrate the effectiveness of the approach compared to conventional charging.