Tampere University of Technology

TUTCRIS Research Portal

Novel online fitting algorithm for impedance-based state estimation of Li-ion batteries

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


Original languageEnglish
Title of host publicationIECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society
Number of pages6
ISBN (Electronic)978-1-7281-4878-6
ISBN (Print)978-1-7281-4879-3
Publication statusPublished - Oct 2019
Publication typeA4 Article in a conference publication
EventAnnual Conference of the IEEE Industrial Electronics Society -
Duration: 1 Jan 1900 → …

Publication series

NameAnnual Conference of the IEEE Industrial Electronics Society
ISSN (Print)1553-572X
ISSN (Electronic)2577-1647


ConferenceAnnual Conference of the IEEE Industrial Electronics Society
Period1/01/00 → …


The impedance of a Li-ion battery is an important parameter for the battery's state-of-charge (SOC) and state-of-health (SOH) estimation. Battery impedance is typically modeled by an equivalent-circuit-model (ECM) in which the variations in the specific model parameters can be used for estimating the SOC and the SOH. However, the fact that the battery impedance is highly non-linear complicates the parameterization of the model. The model is traditionally obtained by a complex non-linear least-squares fitting algorithm which comes with high complexity. This paper proposes a novel approach to extract all the ECM parameters of the battery impedance obtained with online-capable pseudo-random-sequence (PRS) measurements. Although the algorithm has low complexity, it still captures the desired variations in the ECM parameters as a function of SOC. The algorithm is validated for the impedance data from a lithium-iron-phosphate cell.


  • Impedance, Batteries, Computed tomography, Battery charge measurement, Impedance measurement, Electronic countermeasures, Frequency measurement, Li-ion batteries, PRS, Online impedance measurements, SOC, SOH, State-estimation

Publication forum classification