Development of a High-Voltage Battery Pack Thermal Model at Vehicle Level for Plug-in Hybrid Applications

The ongoing global demand for greater energy efficiency plays an essential role in the automotive industry, as the focus is moving from ICEs to hybrid (HEVs) and electric (EVs) vehicles. New virtual methodologies are necessary to reduce the development effort of these technologies. In this context, the thermal management of the vehicle high voltage battery pack is becoming increasingly important, with significant impact on the vehicle’s range in different environmental scenarios.

In this paper, an advanced method is proposed to compute 3D temperature distribution of the cells of a high voltage battery pack for Plug-in Hybrid (PHEV) or full electric (EV) applications. The thermal FE model of a complete PHEV vehicle was integrated with an electrical NTG equivalent circuit model of the HV battery to compute the heat loads of the cells. This model was then coupled with a CFD simulation of the complete vehicle, using a pseudo transient approach able to compute different transient load cases. The model was validated with specific wind tunnel tests performed in the climatic wind tunnel. Several drive cycles were tested to validate the virtual model. The temperature results obtained by the simulation on the battery modules and cells showed a good accuracy compared to the experimental data, both in hybrid and electric drive modes. The distribution of temperature inside the battery was accurately predicted. The developed model demonstrated to be able to characterize and predict the performance of a battery pack. This methodology will allow to easily and rapidly test different battery pack layouts and engineering solutions in the early stages of the vehicle development.