Abstract:

This article investigates real-time fast charging for lithium-ion batteries at high C-rates. First, an electrochemical- thermal-inspired battery model is presented to capture key dynamics accurately. The model is validated through hardware experiments, showing small modeling errors across a wide range of charging (up to 4 C) and discharging (up to 14.5 C) currents. A fast-charging framework is then proposed, consisting of two components: an offline trajectory optimization and an online current reshaping algorithm. First, the offline component solves a time-optimal charging trajectory optimization problem once at the start of the charging process. This generates an optimal reference trajectory for battery states and controls, which is then used by the online component. Second, the online component continually reshapes the reference charging current in real time. Operating at a higher frequency, it adjusts the current based on the present state and the reference current for the next time instance, ensuring compliance with charging constraints. Numerical experiments confirm the effectiveness and computational efficiency of the proposed framework.