Battery Simulation Using the NTGK Model: Effects of Model Parameters and Implementation under Dynamic Current Profiles

Abstract

With the growth in electric powertrain vehicles, the demand for batteries is increasing. Therefore, it is crucial to operate the battery system within an optimum range in terms of performance, life, and safety. In this regard, battery thermal management systems have garnered significant attention for their crucial role in maintaining a battery system within predetermined thermal conditions. The current study focuses on battery simulation using the Newman, Tiedemann, Gu, and Kim (NTGK) model, which is widely applied in the literature. However, the accuracy of this model strongly depends on the empirical parameters U and Y, and existing fitting-based methods often lead to limited reliability. Thus, the effects of the parameters on the temperature evolution of a battery cell were investigated by comparing simulation results with manufacturer data at different discharge rates. This study presents a structured solution scheme to determine the U and Y parameters (for DoD < 0.83). The battery model with the calculated parameters was also simulated under a dynamic current profile representing the Worldwide Harmonized Light Vehicle Test Cycle (WLTC), which is used in approval tests of electric vehicles, at different convective heat transfer coefficients. The results show that temperature prediction with the solution scheme is in good agreement with the battery data obtained from its datasheet. The Y parameter in the NTGK model is of great importance for the development of heat generation characteristics, which in turn affects temperature development. The maximum temperature increase under WLTC was found to be 3.08°C at 20 W/m2K and 8.87°C at 5 W/m2K, while the absolute temperature prediction errors remained below 2.67 K. The temperature rise under dynamic load is consistent with the literature, supporting the validity of the proposed solution scheme.