OBSERVER-BASED ESTIMATION OF SOC OF LI-ION BATTERY

Abstract

Lithium-ion batteries are becoming an essential energy storage technology, from electric cars to portable devices. For lithium-ion batteries to operate as efficiently and last as long as possible, accurate state of charge (SOC) measurement is key. This paper explores the latest Sliding Mode Observer (SMO) technique for lithium-ion battery SOC estimation. The SMO method improves the resilience and accuracy of SOC estimates by combining the advantages of ellipsoid-based techniques and sliding mode control. In the context of lithium-ion batteries, this paper examines the theoretical underpinnings, modeling concerns, simulation findings, and possible applications of the SMO approach. The underlying theory of the observer design extends beyond estimating the state of charge (SOC) in lithium-ion cells. It can be applied to a broader range of nonlinear systems encompassing matched and mismatched uncertainties. The primary benefit of the proposed observer is its ability to provide a rapid and optimal SOC estimate through minimization over the uncertainty bound. In the field of lithium-ion battery SOC estimation, this work developed an improved sliding mode observer strategy that effectively addresses the issue of high-frequency chattering in conventional observation techniques. The approach is based on the state equation matching the second-order RC equivalent circuit model, created in constrained uncertainties and external disturbances. The response of the simulation model under the complex charge-discharge conditions is used to test the upgraded SMO algorithm, demonstrating its robustness and efficacy.