A Reduced-Component-Count Centralized Equalization System for Series-Connected Battery Packs Based on a Novel Integrated Cascade Topology

Abstract

In this article, a reduced-component-count centralized equalization system based on a novel integrated cascade equalization topology is proposed to achieve the equalizing of series-connected battery packs. The proposed converter topology is the integration of the polarity switches and the bidirectional converter in traditional centralized battery equalization systems, and can also be regarded as a cascade structure composed of a bidirectional buck-boost and a bidirectional flyback converter. Compared with existing centralized equalizers, the number of components applied on the proposed scheme is significantly reduced, which obtains higher cost performance and reliability, and is more suitable for the equalization of large-capacity battery packs. Meanwhile, this integrated cascade structure enables the proposed topology to achieve an ultra-high voltage conversion ratio; hence, the efficiency can be significantly enhanced by employing a transformer with a smaller turns ratio and reduced leakage inductance. Furthermore, the operating principles, design considerations, and comparative analysis are presented in detail. Finally, an experimental prototype based on a 13-cell lithium-ion battery pack is established to verify the superior performance of the proposed equalization system.