Online Optimal Charging Strategy for Lithium-Ion Batteries Based on Model Predictive Control at Relatively High Temperatures

Conventional charging protocols of lithium-ion batteries (LIBs) are challenged with the balance between charging speed, battery safety, and cycle life, especially at relatively high temperatures. In this work, a novel online optimal charging method based on model predictive control (MPC) is addressed to handle the above issues. A new thermo-electric coupled equivalent circuit model which decomposes the cathode and the anode is constructed to precisely estimate the cell temperature and internal anode voltage. The model is then integrated into the MPC control framework to generate the optimum real-time applied current. The designed charging protocols consist of not only continuous current optimal charging (CCOC) but also pulsed current optimal charging (PCOC) which can moderate the cell heat generation and temperature rise. It can be concluded that the PCOC method significantly reduces the charging duration compared with the CCOC. Simulation results of the developed charge control algorithm under different initial SOCs and initial temperatures are also discussed, which verify the robustness of the proposed charging strategy.