Simultaneous State of Charge and Total Capacity Estimation of Lithium-ion Cells Using Multiple Model Adaptive Estimation

Accurate State of Charge (SOC) and cell capacity estimation are needed to ensure effective performance monitoring of Lithium-ion battery management systems. In this work, a Multiple Model Adaptive Estimation (MMAE) technique is implemented to estimate SOC and cell total capacity simultaneously with an Enhanced Self-Correcting (ESC) model. In MMAE technique, conditional probabilities of all possible capacity values are computed to find the most likely cell capacity estimate, and SOC estimate is then calculated based on the given probabilities. Simulation results for a LiFePO4 Lithium-ion cell demonstrate that MMAE technique provides smaller estimation error compared to Joint and Dual estimation techniques as well as robust estimation results under poor initial SOC and cell capacity choices.