Novel low-complexity model development for Li-ion cells using online impedance measurement

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Modeling of Li-ion cells is used in battery management systems (BMS) to determine key states such as state-of-charge (SoC), state-of-health (SoH), etc. Accurate models are also useful in developing a cell-level digital-twin that can be used for protection and diagnostics in the BMS. In this paper, a low-complexity model development is proposed based on the equivalent circuit model (ECM) of the Li-ion cells. The proposed approach uses online impedance measurement at discrete frequencies to derive the ECM that matches closely with the results from the electro-impedance spectroscopy (EIS). The proposed method is suitable to be implemented in a microcontroller with low-computational power, typically used in BMS. Practical design guidelines are proposed to ensure fast and accurate model development. Using the proposed method to enhance the functions of a typical automotive BMS is described. Experimental validation is performed using large prismatic cells and small-capacity cylindrical cells. Root-mean-square error (RMSE) of less than 3% is observed for a wide variation of operating conditions.

Original languageEnglish
Article number112029
JournalJournal of Energy Storage
Volume91
ISSN2352-152X
DOIs
Publication statusAccepted/In press - 2024

Keywords

  • Battery impedance
  • Digital-twin
  • Equivalent circuit model
  • Li-ion batteries

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