Advanced MPC-Based Bidirectional Equalization for Energy Balancing in Series-Connected EV Battery Cells

Cell imbalance in series-connected battery packs, typically caused by repeated charge–discharge cycles, negatively impacts capacity, lifespan, and safety in electric vehicle (EV) applications. To address these issues, effective and reliable cell balancing is critical for maintaining battery performance and ensuring consistent energy delivery. Conventional balancing approaches often face drawbacks such as inefficient charge redistribution, limited control of energy flow, and slower response. Although bidirectional equalization strategies reduce the risks of overcharging and overdischarging, challenges remain in achieving high balancing speed, superior energy efficiency, and reduced circuit complexity. This study introduces an active bidirectional cell-to-cell equalization strategy based on a multi-winding transformer topology, where energy is directly transferred from higher-voltage to lower-voltage cells through flyback operation. A time-sharing control algorithm guided by initial state-of-charge (SoC) optimizes the sequence and prevents unnecessary transfers, while an advanced Model Predictive Control (MPC) scheme further enhances dynamic regulation, efficiency, and robustness of the balancing process. The proposed system is validated using MATLAB/Simulink 2019b and real-time hardware-in-the-loop testing with the OPAL-RT OP5700 platform, demonstrating superior equalization speed and energy utilization compared to conventional techniques.