An Open Circuit Voltage Model Fusion Method for State of Charge Estimation of Lithium-Ion Batteries

Quanqing Yu, Changjiang Wan, Junfu Li, Lixin E, Xin Zhang, Yonghe Huang and Tao Liu
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Quanqing Yu: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Changjiang Wan: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Junfu Li: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Lixin E: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Xin Zhang: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Yonghe Huang: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Tao Liu: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China

Energies, 2021, vol. 14, issue 7, 1-22

Abstract: The mapping between open circuit voltage (OCV) and state of charge (SOC) is critical to the lithium-ion battery management system (BMS) for electric vehicles. In order to solve the poor accuracy in the local SOC range of most OCV models, an OCV model fusion method for SOC estimation is proposed. According to the characteristics of the experimental OCV–SOC curve, the method divides SOC interval (0, 100%) into several sub-intervals, and respectively fits the OCV curve segments in each sub-interval to obtain a corresponding number of OCV sub-models with local high precision. After that, the OCV sub-models are fused through the continuous weight function to obtain fusional OCV model. Regarding the OCV curve obtained from low-current OCV test as the criterion, the fusional OCV models of LiNiMnCoO 2 (NMC) and LiFePO 4 (LFP) are compared separately with the conventional OCV models. The comparison shows great fitting accuracy of the fusional OCV model. Furthermore, the adaptive cubature Kalman filter (ACKF) is utilized to estimate SOC and capacity under a dynamic stress test (DST) at different temperatures. The experimental results show that the fusional OCV model can effectively track the performance of the OCV–SOC curve model.

Keywords: electric vehicles; lithium-ion batteries; open circuit voltage; state of charge; model fusion; adaptive cubature Kalman filter (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (15)

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