A Fractional-Order Model-Based Method for Co-Estimating State-of-Charge and Core Temperature in Lithium-Ion Batteries

Accurate real-time estimation of a battery’s state of charge (SOC) and internal temperature is essential for improving the safety and reliability of battery systems. However, these states are difficult to measure directly in real time. To address this challenge, this paper develops a fractional-order electrothermal coupled model and integrates it with an extended Kalman filter (EKF) to jointly estimate SOC and internal temperature without additional sensors. Experimental results under various operating conditions show that the SOC estimation error is within ±0.01 and the internal temperature error is within ±2 °C. These results demonstrate the effectiveness and feasibility of the proposed joint estimation method.