Modeling of a direct liquid thermal management system for electric vehicle batteries

In recent years, concern about climate change has been increasing due to its increasingly evident effects and electrification is the most relevant alternative to the traditional combustion engine. The battery pack is the heart of the system and Li-ion cells are the most used. Weight and thermal management are the main factors affecting EV performance and efficiency. A scaled-down version of an innovative battery pack designed for high-voltage applications on BEVs, which adopts an immersion cooling system while implementing cell-to-pack integration, is the subject of this thesis. The work carried out is divided into two parallel activities. On one hand, the development of the electrical model of the 48V battery pack with a capacity of 20 Ah. The battery model integrated in the thermal management system model which is used to develop an effective control logic that can ensure the optimal temperature of the cells, thus improving the performance and lifespan of the battery pack. The second activity involves the physical implementation of a test bench to test and validate the developed logic. This requires the design and creation of an experimental system capable of simulating the real operating conditions of the battery pack, allowing the evaluation of the control logic's effectiveness in various scenarios and conditions. The model that represents the thermal behavior of the battery pack and the heat exchange between cells and coolant, has been implemented using MATLAB and Simulink environment. The results obtained from the model provide preliminary information for the development of the first prototype, whose experimental data will be used to validate the model and optimize the design and performance of the cooling system. The results confirm the effectiveness of the cooling strategies adopted. This work provides a solid foundation for the development of advanced thermal management technologies for lithium batteries.