Title: Design and control of bidirectional active balancing model for lithium-ion battery pack

Authors: Qiuting Wang; Wei Qi

Addresses: Department of Electrical and Information Engineering, Zhejiang University City College, 51 Huzhou Road, Hangzhou, 310015, China ' Department of Electrical and Information Engineering, Zhejiang University City College, 51 Huzhou Road, Hangzhou, 310015, China

Abstract: The performance of battery cells and serial/parallel pack will be inconsistent, because of the deviation of production process and the different application environment. The overall capacity of lithium-ion battery pack will easily decline. In our study, an efficient bidirectional balancing method based on least squares algorithm and optimal control strategy is proposed. The bidirectional DC/DC converter is designed to transfer the energy between one cell and the adjacent cell. The predictive control (PC) algorithm based on cell state of charge (SOC) value is established. The experimental results indicate that bidirectional active balancing model can effectively reduce the voltage difference between battery cells. The optimal control strategy can overcome the shortcomings of traditional strategy such as low energy transfer efficiency, long equalisation time and unsuitable for large capacity. Besides, it can avoid unnecessary energy loss and reduce the balancing time by 28%.

Keywords: lithium-ion battery; serial/parallel pack; bidirectional balancing circuit; predictive control; DC/DC converter; SOC; state of charge.

DOI: 10.1504/IJMIC.2020.116910

International Journal of Modelling, Identification and Control, 2020 Vol.36 No.3, pp.240 - 247

Received: 07 Jun 2020
Accepted: 19 Sep 2020

Published online: 02 Aug 2021 *

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