Diagnosis of LIB Degradation using Estimating Cell Resistance for Hybrid Electric Vehicles

Abstract

-To get computationally efficient algorithm which can diagnose the cell degradation by estimating the cell resistance in a battery management system (BMS), the ordinary least squares estimator (LMS filter) is employed to identify the parameter in the simple resistance model in the form of a first-order polynomial. As a result, the determined parameter estimate, the slope in the model, can be adapted to changes in the battery resistance. The devised algorithm is validated by using the cells with different state-of-health. These cells are aged at the elevated temperature over 24 weeks and tested at every four weeks to monitor changes in the cell resistance. Consequently, the devised algorithm can distinguish between the cell resistances which increase by 2 to 4% at every month.