Comparative Analysis of Capacitor-Based Active Cell Balancing Topologies for Lithium-Ion Battery Packs

With the rising demand for high-energy-density power sources, lithium-ion battery packs have become essential for powering electric vehicles, renewable energy systems, and numerous applications. However, imbalances in individual cells can reduce performance, lifespan, and yield safety concerns. Therefore, cell balancing becomes crucial to equalize battery packs. While passive balancing is common for its cost-efficiency and simplicity, this paper focuses on active cell balancing, specifically capacitor-based topologies, due to their low cost and ease of control. Two primary topologies were analyzed: the chain structure switched capacitor and the single switched capacitor configuration. These techniques were tested on a 6S1P battery pack of 18650 lithium-ion cells. From the software simulations, it was deduced that passive cell balancing resulted in the fastest balancing speed, followed by the two switched capacitor configurations. However, this came at the expense of wasting the excess energy into heat, with which the capacitor-based topologies optimized by cycling the charge. Nevertheless, considering the frequency of balancing throughout the battery lifespan, passive cell balancing proves to be more suitable for low- to mid-power applications, while the benefits of active cell balancing become more evident for high power applications.