Double-Layer Multiwinding Transformer-Based Modular-Integrated Equalizer for Extended Battery String

This article presents a double-layer-integrated charging equalizer based on magnetic coupling to address battery module imbalances. The proposed architecture consists of a main transformer and parallel transformers. The main transformer ensures the overall module balance, while the parallel transformers achieve individual cell balancing. The system eliminates the need for additional magnetic components and operates independently. The experimental results on a nine-cell (three modules) setup demonstrate its reduced voltage variation during charging mode, with an efficiency of 90.1% at 35-W output. The proposed solution offers an effective and practical approach to address battery module imbalances in a concise manner.