A Voltage-Based Charge Balancing Algorithm to Mitigate the Charge Recovery Effect of Li-ion Batteries

The design and control of the active charge balancing (ACB) architecture are essential functionalities performed by a battery management system (BMS) in lithium-ion battery (LiB) applications. In many applications, the charge balancing control of the battery packs is implemented using state of charge (SOC) estimation methods. A similar approach can be implemented for cell-level balancing operations. However, such SOC-based balancing control introduces the cost of additional hardware for the ACB circuit and more computational cost on the controller. Therefore, voltage-based charge balancing algorithms have been preferred in the literature to overcome the cost and complexity. A limitation is not considering the voltage recovery effect, a dominating phenomenon observed with a high charge rate of the balancing current. An efficient charge-balancing algorithm has been proposed in this study, considering the charge recovery effect of each series cell. The balancing operations are performed on a 4S8P battery pack configured using ICR 18650-26j commercial Li-ion cells. An experimental results are presented to validate the proposed balancing strategy.