Abstract:

The module arrangement of passenger car power battery packs usually has three different forms： single-layer arrangement， duplex arrangement and local duplex arrangement. The local duplex arrangement， which combines the characteristics of the other two methods， is more widely used. However， the study of electric vehicle fire accidents shows that battery packs with local duplex arrangement account for a higher proportion of spontaneous combustion accidents， which indicates that this arrangement may adversely affect the thermal uniformity of the battery module. In view of this， in this paper taking an electric vehicle battery pack with local duplex arrangement as the research object， a three-dimensional numerical model of the battery pack is established and the accuracy of the model is verified by comparing the experimental data with the simulation results. Using the validated model， the module temperature distribution characteristics of the battery pack under fast charging and three discharge rates are analyzed by numerical calculation methods， revealing the thermal uniformity of the local duplex arrangement of the modules under these conditions， especially the with the temperature difference of the double-layer module in the local duplex module larger than that of the single-layer module. In addition， the effect of coolant inlet temperature and flow rate on the thermal uniformity of the modules is explored respectively. It is found that attempting to reduce the coolant inlet temperature to improve the thermal uniformity of the module has limited effect， while increasing the coolant inlet flow rate can only reduce the temperature difference of the module under high discharge rate conditions， without obvious effect under low discharge rate conditions. This study provides a meaningful reference for the development and design of the battery thermal management system with local duplex modules.

Key words: thermal uniformity, coolant inlet temperature, coolant inlet flow rate, module discharge rate