Energy storage devices have become an important part of many mobile applications, such as conventional, electric or hybrid electric vehicles. For an optimal and efficient system design, simulation models have become an inevitable tool. Accuracy over a wide range of operating conditions is very important. However, electrochemical storage devices are strongly nonlinear and often show inhomogeneous current distribution leading to performance and lifetime limitations.
Keywords -Battery model, electric vehicle, electric drive train, impedance-based model, lithium-ion battery.
I. INTRODUCTIONVarious simulation models for batteries and other electrochemical storage systems exist for a wide range of applications. Typical applications are the design and dimensioning of battery driven or supported systems, battery development or battery and energy management systems. In the first case, the simulation model is an important tool e.g. to evaluate suitable battery technologies, to find suitable dimensions in volume, weight and electrical properties, to test if system and battery are compatible in all operating conditions, to test charge procedures or resulting current profiles from drive cycles and to predict the lifetime of a battery in a certain application. For battery and energy managements, a battery model is necessary to predict the condition of the battery, e.g. state of charge (SOC) or state of health (SOH), and if the battery will be able to deliver the power for a certain operation, state of function (SOF). Depending on aims and requirements of use, different kinds of models are needed. The realisation of a model is always a compromise between precision and computation time.In this paper, a lithium-ion battery model is used to evaluate the suitable size of a pack for an electric-vehicle drive train.