SOC Estimation of Lithium-Ion Battery Pack Considering Balancing Current

The state-of-charge (SOC) estimation approaches based on the pack model can hardly provide precise estimation due to cell difference, while the approaches based on each cell cost high computation resource, which are not suitable for real-time application. The estimation error can be further enlarged...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2018-03, Vol.33 (3), p.2216-2226
Main Authors: Zhang, Zhiliang, Cheng, Xiang, Lu, Zhou-Yu, Gu, Dong-Jie
Format: Article
Language:English
Subjects:
Adaptive extended Kalman filter
balancing current
Batteries
battery pack
Charging
Discharges (electric)
Errors
Estimation
Integrated circuit modeling
Laplace equations
Lithium
Lithium-ion batteries
Mathematical models
Rechargeable batteries
Reduction
State of charge
state of charge (SOC)
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Summary:The state-of-charge (SOC) estimation approaches based on the pack model can hardly provide precise estimation due to cell difference, while the approaches based on each cell cost high computation resource, which are not suitable for real-time application. The estimation error can be further enlarged without considering balancing current. The SOC estimation approach of the battery pack considering balancing current is proposed, which dynamically searches for the cell with maximum or minimum voltage, and it only needs to calculate the selected cell in every estimation cycle. Compared to the approaches based on the pack model or each single cell, this approach can achieve precise pack SOC and cost less calculation time and resource. It has been verified with ten series-connected 200 Ah Li(NiCoMn)O2 batteries. The SOC estimation error is limited to 0.3% during the charging process, and a reduction of 2.5% is achieved compared to an error of 2.8% based on the pack model. A reduction of 1% is achieved compared to an error of 1.5% based on the pack model during the discharging process. Compared to an error of 1.7% without considering balancing current, a reduction of 1.4% is achieved during the charging process.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2017.2700324