(75b) Estimation Methods for Battery State of Charge Determination

Battery systems do not explicitly indicate the existing state of charge. Parameters such as capacity change with time, temperature, and usage characteristics. Using available measurements along with high-fidelity models, online estimation routines can be applied to determine the state of health of the battery system.

Various methods have been used in the past to examine this problem. These methods include Moving Horizon Estimation (MHE), Extended Kalman Filter (EKF), and Unscented Kalman Filter (UKF). Past applications examined only tracking of the existing instantaneous parameter values related to the state of charge. It is proposed to examine online determination of the rate of change for various battery system parameters.