Individual Cell Equalization for Series Connected Lithium-Ion Batteries

Yuang-Shung LEE  Ming-Wang CHENG  Shun-Ching YANG  Co-Lin HSU  

IEICE TRANSACTIONS on Communications   Vol.E89-B   No.9   pp.2596-2607
Publication Date: 2006/09/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.9.2596
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Energy in Electronics Communications
bi-directional converter,  DCVM Cuk converter,  lithium-ion battery,  individual cell equalizer,  ZVS,  

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A systematic approach to the analysis and design of a bi-directional Cuk converter for the cell voltage balancing control of a series-connected lithium-ion battery string is presented in this paper. The proposed individual cell equalizers (ICE) are designed to operate at discontinuous-capacitor-voltage mode (DCVM) to achieve the zero-voltage switching (ZVS) for reducing the switching loss of the bi-directional DC/DC converters. Simulation and experimental results show that the proposed battery equalization scheme can not only enhance the bi-directional battery equalization performance, but also can reduce the switching loss during the equalization period. Two designed examples are demonstrated, the switch power losses are significantly reduced by 52.8% from the MOSFETs and the equalization efficiency can be improved by 68-86.9% using the proposed DCVM ZVS battery equalizer under the specified cell equalization process. The charged/discharged capacity of the lithium-ion battery string is increased by using the proposed ICEs equipped in the battery string.