IEEE Access, DOI: 10.1109/ACCESS.2022.3148528.

Dynamic Equivalent Circuit Model to Estimate State-Of-Health of Lithium-Ion Batteries

S. Amir2, M. Gulzar2, M. O. Tarar2, I. H. Naqvi2, N. A. Zaffar 2 and M. Pecht1

1 Center for Advanced Life Cycle Engineering (CALCE), University of Maryland, College Park, MD, USA
2 Department of Electrical Engineering at Lahore University of Management Sciences (LUMS), Lahore, Pakistan 54792.


Lithium-ion (Li-ion) batteries have increasingly been used in diverse applications. Accurate estimation of the state of health (SOH) of the Li-ion batteries is vital for all stakeholders and critical in various applications such as electric vehicles (EVs). The electrical equivalent circuit (EEC) 2-RC model is often used to model the battery operation but has not been used to capture the degradation of battery cells over time. This paper uses the 2-RC model to capture the degradation of the Li-ion battery. The proposed model is not only time-dependent but also captures the effect of temperature on battery degradation. The proposed approach estimates the SOH accurately and is also considerably flexible for diverse cells of different chemistry. We further generalize an N-RC model approach to evaluate the SOH of the battery. We compare the proposed model (2-RC) with the 1-RC model, and through numerical results, we show that the 2-RC model outperforms 1-RC and reduces the computational cost significantly. Similarly, the 2-RC model outperforms 3-RC and higher-order circuits. We also show that the proposed approach can capture the battery dynamics better for specific smaller orders of the polynomial (associated with Arrhenius equation) when compared with the 1-RC approach with considerably reduced (up to 60%) root mean square error (RMSE). Lastly, the average testing RMSE for 2-RC is 52.4%.

This article is available online here for free.

[Home Page] [Articles Page]
Copyright © 2021 by CALCE and the University of Maryland, All Rights Reserved