Performance Analysis of R-int Approximation in Battery Equivalent Circuit Models

Document Type

Conference Proceeding

Publication Date


Publication Title

1st IEEE Industrial Electronics Society Annual On-Line Conference, ONCON 2022


battery equivalent circuit model, Battery management system, Cramer-Rao lower bound, ECM parameter esti-mation, performance analysis of ECM parameter estimation


Battery management systems are crucial for the safety and efficiency of a battery pack. Equivalent circuit modelling of a battery is widely used by battery management systems to estimate the state of charge, state of health and available power. However, equivalent circuit model parameter es-timation is computationally intensive and can be suboptimal when higher-order non-linear models are selected. Implementation of advanced system identification techniques is nearly impossible in many practical applications due to computational and power constraints for battery management. Due to this, simplified, reduced-order equivalent circuit models are widely adopted in battery management systems. In this paper, we propose an efficient approach to estimate the parameters of the R-int reduced order equivalent circuit model. Theoretical performance analysis is presented by deriving the Cramer-Rao lower bound on the estimation error variance. Using this, detailed performance analysis and insights into the R-int model approximation are presented. It is noted that the R-int approximation yields a highly accurate estimation of combined series resistance, in terms of the normalized mean squares error, when the time constant is low.