A Multi-Layer Equalizer Based on Isolated Bidirectional Cuk Converter

To address the issue of energy imbalance among individual cells in a series-connected lithium-ion battery pack, this paper proposes a multi-layer balancing circuit based on Buck-Boost and isolated bidirectional Cuk converters. The internal structure of the equalizer employs a Buck-Boost topology for active parallel balancing of battery modules in its first and second layers, while utilizing an isolated bidirectional Cuk topology for chain equalization in the third layer. Firstly, a detailed analysis of the principle of the proposed equalizer circuit was conducted; secondly, the parameters of the proposed equalizer were designed based on the circuit analysis. Finally, an experimental platform for 12-cell battery storage was constructed to conduct balancing experiments under different conditions. The experimental results demonstrated the feasibility and advantages of the proposed equalizer, including its rapid balancing capability and feasibility of modular design, making it particularly suitable for large-scale energy storage battery systems.