Development of dynamic battery thermal model integrated with driving cycles for EV applications

Abstract

Accurate thermal analysis of batteries for realistic operating conditions is a key requirement to develop an effective battery thermal management system of electric vehicles (EV), which ensures battery safety. In this context, a dynamic battery thermal model is developed to investigate the thermal characteristics of the battery module under dynamic EV operating conditions. The comprehensive modeling on EV dynamics is firstly conducted to determine the power demands with driving cycle applications. The efficiencies of components within the EV powertrain are closely considered, and the power consumed or regenerated in traction or brake mode is estimated. The battery thermal model considering both the joule and entropic heats is developed to predict the heat generation rates and temperature profiles following the dynamic battery loads. The developed models are validated within 3.98% for the EV dynamics model and 0.76% for the battery thermal model in relative error, respectively, allowing precise power and thermal simulation under the realistic operating conditions of the EV battery. A comparative analysis between the dynamic and steady modes for the same power loads to confirm the effects of the dynamic patterns is conducted for ten continuous cycles. As a result, the maximum differences between steady and dynamic modes are discovered about 3.57 times in heat generation, and 4.58 degrees C in temperature. These differences remain significant even with the thermal management, turning out more active cooling is required for normal operation under dynamic operating conditions.