On-line equalization for lithium-ion battery packs based on charging cell voltages: Part 1. Equalization based on remaining charging capacity estimation

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• 作者：Yuejiu Zheng ; Minggao Ouyang ; Languang Lu ; Jianqiu Li ; Xuebing Han ; Liangfei Xu
• 关键词：Electric vehicle ; Battery pack ; Cell variations ; Cell equalization ; Capacity estimation ; Charging voltage
• 刊名：Journal of Power Sources
• 出版年：1 February, 2014
• 年：2014
• 卷：247
• 期：Complete
• 页码：676-686
• 全文大小：1462 K

文摘

Because of the inevitable inconsistency during manufacture and use of battery cells, cell variations in battery packs have significant impacts on battery pack capacities, durability and safety for electric vehicles (EVs). To reduce cell variations and increase pack capacity, cell equalization is essentially required. In the series of two papers, we discover that dissipative cell equalization (DCE) using dissipative resistances is a feasible on-line equalization method for battery packs in EVs. We subsequently propose on-line equalization algorithms for lithium-ion battery packs based on charging cell voltage curves (CCVCs). The objective of these algorithms is to maximize pack capacities by conditioning CCVCs.

As the first paper of the series, we first briefly review equalization topologies and algorithms. We discover cell remaining charging capacity (RCC) can be on-line estimated and further propose DCE algorithm based on remaining charging capacity estimation (RCCE). We establish a pack model with 8 cells in series and simulate 4 scenes with different cell variations. RCCE-DCE algorithm is proved to be effective by comparing pack capacities with/without RCCE-DCE algorithm. The equalization capability and over-equalization prevention are further examined, and the result shows that RCCE-DCE algorithm is suitable for on-line equalization in EVs.