Improving battery thermal behavior and consistency by optimizing structure and working parameter

Abstract Improving battery consistency is the one of the main goals of battery management system (BMS). As its subsystem, the battery thermal management system (BTMS) should try to accomplish this aim. However, the traditional design of the BTMS considers only the battery temperature and temperature difference, and does not considers their influence on the battery consistency. This study establishes an electro-thermal model for an air-cooled pack. The coupled model can accurately predict the electrical and thermal behavior of the pack. At the pack level, the maximum prediction error of the terminal voltage is 0.58 V, and the maximum average relative error of temperature is only 1.73%. The coupled model is used to optimize the air channel and air speed. In order to improve consistency of the battery, the difference of state of charge (SOC) is added as the evaluation parameter in the optimization of the air channel and air velocity. The optimization process of the structure is divided into two phase and the dual DOEs (design of experiment) are applied. The DOE results are analyzed by the range and variance to select the structure with the best comprehensive performance. Compared with the original air channel and air velocity, the optimized air channel with the new air velocity reduces the maximum cell temperature and temperature difference by 2.67 °C and 1.11 °C respectively, makes the SOC difference falls from 0.37% to 0.29% in a discharging process, under the severest design condition. Moreover, the optimized pack is proved to have a better performance under other conditions.