Battery Internal Temperature Estimation for LiFePO 4 Battery Based on Impedance Phase Shift under Operating Conditions

Jiangong Zhu, Zechang Sun, Xuezhe Wei and Haifeng Dai
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Jiangong Zhu: Clean Energy Automotive Engineering Center, Tongji University, Shanghai 201804, China
Zechang Sun: Clean Energy Automotive Engineering Center, Tongji University, Shanghai 201804, China
Xuezhe Wei: Clean Energy Automotive Engineering Center, Tongji University, Shanghai 201804, China
Haifeng Dai: Clean Energy Automotive Engineering Center, Tongji University, Shanghai 201804, China

Energies, 2017, vol. 10, issue 1, 1-17

Abstract: An impedance-based temperature estimation method is investigated considering the electrochemical non-equilibrium with short-term relaxation time for facilitating the vehicular application. Generally, sufficient relaxation time is required for battery electrochemical equilibrium before the impedance measurement. A detailed experiment is performed to investigate the regularity of the battery impedance in short-term relaxation time after switch-off current excitation, which indicates that the impedance can be measured and also has systematical decrement with the relaxation time growth. Based on the discussion of impedance variation in electrochemical perspective, as well as the monotonic relationship between impedance phase shift and battery internal temperature in the electrochemical equilibrium state, an exponential equation that accounts for both measured phase shift and relaxation time is established to correct the measuring deviation caused by electrochemical non-equilibrium. Then, a multivariate linear equation coupled with ambient temperature is derived considering the temperature gradients between the active part and battery surface. Equations stated above are all identified with the embedded thermocouple experimentally. In conclusion, the temperature estimation method can be a valuable alternative for temperature monitoring during cell operating, and serve the functionality as an efficient implementation in battery thermal management system for electric vehicles (EVs) and hybrid electric vehicles (HEVs).

Keywords: lithium-ion battery; internal temperature estimation; impedance; phase shift; electric vehicles (EVs) (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: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (6)

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