Electro-Thermal Coupling Modeling Method Based on the Constant-Current External Characteristics of Lithium-Ion Battery

Battery management systems (BMS) are primarily based on battery models for state estimation and management of lithium-ion batteries. However, variables that affect battery parameters include current, state of charge (SOC), temperature, etc. These variables also exhibit nonlinear coupling effects, making it difficult to establish an accurate battery model. Therefore, this paper proposes an electro-thermal coupled modeling method for lithium-ion battery. The method involves constructing models based on external characteristics data such as battery voltage and temperature. Firstly, multiple sets of constant current operating condition experiments are designed to obtain experimental data that include current, SOC, and temperature information. Secondly, the Arrhenius equation is selected as the architecture for the battery voltage model to describe the nonlinear relationship between voltage and temperature, with the quantitative influence of current and SOC reflected in the parameters of the equation. Then, the Bernardi model is chosen as the battery thermal model to estimate real-time battery temperature. Finally, the accuracy of this electro-thermal coupled modeling method is validated through experimental voltage data. The experimental results show that the modeling method is feasible and has high accuracy.