Active Balancing of Lithium-Ion Batteries Using Graph Theory and A-Star Search Algorithm
Journal article, 2021

The heterogeneity of cells in a battery pack is inevitable but brings high risks of premature failure and even safety hazards. Accordingly, for safe and long-life operation, it is necessary to adjust the state of charge (SOC) of all in-pack cells to the same level. To address this problem, this article first proposes a battery SOC observer and analyzes its stability and convergence analysis using the Lyapunov direct method. Different to most available estimators is that the proposed method does not require the information of cell capacities. Then, after modeling the equalization system as a directed graph, the equalization problem is cast as a path searching problem. Finally, an A-star algorithm subject to balancing constraints is proposed to find the shortest path in this graph, corresponding to the most efficient SOC equalization. Experimental results show that the steady-state error of the proposed observer is less than 2%. It also demonstrates that the A-star algorithm can decrease the balancing time and energy loss during the balancing process by 9.59% and 19.5%, respectively, relative to the mean-difference-average method.

parallel operation

power converter

state estimation

Cell balancing

lithium-ion battery


Guangzhong Dong

City University of Hong Kong

Fangfang Yang

City University of Hong Kong

Kwok-Leung Tsui

City University of Hong Kong

Changfu Zou

Chalmers, Electrical Engineering, Systems and control

IEEE Transactions on Industrial Informatics

1551-3203 (ISSN) 19410050 (eISSN)

Vol. 17 4 2587-2599 9099954

Subject Categories

Computational Mathematics

Biomedical Laboratory Science/Technology

Control Engineering



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Latest update

4/5/2022 6