Attractive Ellipsoid Sliding Mode Observer Design for State of Charge Estimation of Lithium-ion Cells

TL;DR

This paper introduces a novel attractive ellipsoid sliding-mode observer for real-time state-of-charge estimation of Lithium-ion batteries, enhancing accuracy and robustness under uncertainties and disturbances.

Contribution

It proposes a new AESMO algorithm that improves SoC estimation accuracy and robustness, applicable to nonlinear systems with uncertainties.

Findings

Effective real-time SoC estimation demonstrated on test data

Robustness against parameter uncertainties and disturbances

Fast and optimal estimation performance

Abstract

This work investigates the real-time estimation of the state-of-charge (SoC) of Lithium-ion (Li-ion) cells for reliable, safe and efficient utilization. A novel attractive ellipsoid based sliding-mode observer (AESMO) algorithm is designed to estimate the SoC in real-time. The algorithm utilizes standard equivalent circuit model of a Li-ion cell and provides reliable and efficient SoC estimate in the presence of bounded uncertainties in the battery parameters as well as exogenous disturbances. The theoretical framework of the observer design is not limited to the SoC estimation problem of Li-ion cell but applicable to a wider class of nonlinear systems with both matched and mismatched uncertainties. The main advantage of the proposed observer is to provide a fast and optimal SoC estimate based on minimization over the uncertainty bound. The proposed method is experimentally tested and evaluated using the hybrid pulse power characterization test (HPPC)and urban dynamometer driving schedule (UDDS) test data, which demonstrate its effectiveness and feasibility.