An improved distributed electro-thermal coupled model for liquid-cooled battery pack based on thermal resistance network

Abstract

This study develops a computationally efficient distributed electro-thermal model for predicting voltage and temperature distributions in a liquid-cooled battery pack, with potential for real-time application. A pipe network model calculates the coolant flow distribution and local convective heat-transfer coefficients, while a three-dimensional thermal resistance network predicts the internal temperature field at low computational cost. The electrical and thermal models are coupled by updating cell resistance and polarization capacitance according to local cell temperature and state of charge (SOC). The model therefore quantifies the effect of cooling-induced temperature non-uniformity on cell-to-cell voltage inconsistency. Experimental validation shows that the model accurately predicts pack terminal voltage and temperatures at the available sensor locations while providing additional internal temperature information. The maximum terminal-voltage error is 6.77 V (1.85%), and the maximum temperature root-mean-square error is 0.71 °C. Under 40 °C/1C discharge, the temperature difference measured by the top-mounted BMS sensors is 3.6 °C, whereas the predicted three-dimensional temperature difference is 10.26 °C, indicating that the model provides temperature information beyond the BMS measurement coverage. Under the same condition, the maximum predicted cell-to-cell voltage difference at the end of discharge is 0.011 V.