Abstract
The ongoing activities in the electrification of the conventional vehicle technology offer a great chance for an important contribution to the protection of the environment by helping to reduce and keep CO2 emissions low. A crucial step for developing innovative electrical vehicles is the successful exploitation of new technologies. Due to the need for a convenient range for electric vehicles (EV), lithium-ion technologies are very attractive for such systems. As they provide proper operating characteristics such as high energy density, cycle stability etc. they are often used in battery systems for automotive applications. Thus also a growing demand in special simulation software for lithium-ion battery cells has been recognized in recent years.
In this contribution the development, modeling and validation of multiphysical battery models using the description language Modelica will be presented in order to embrace the need for simulation models for electric energy storages. Modelica is a modern, object-oriented modeling language which is specialized on modeling complex multiphysical systems. The battery models developed in this work are provided in the Electric Energy Storages (EES) library which allows simulating the operating behavior of lithium-ion batteries on cell and stack level considering the mutual influence of electric, thermal and aging effects on each other.
The electric parameters of one particular battery cell are estimated on the basis of measurement data, generated at AIT’s battery testing laboratory. For validation, an FTP-72 load cycle is applied to the configured battery model and the real battery in order to compare the simulated and the measured operating behavior.
The developed EES library allows simulating a wide range of different battery technologies for various practical user applications such as vehicle to grid scenarios or function development of a battery management system. Thereby key aspects like electric, thermal and aging effects can be considered and evaluated with respect to the operating mode of the battery.
KEYWORDS – Electric Energy Storages (EES), Equivalent Circuit Model, Multiphysical Modeling and Validation, Parameter Estimation, Aging