A circuit-equivalent battery model accounting for the dependency on load frequency

Circuit-equivalent battery models are considered defacto standard for modeling and simulation of digital systems due to many practical advantages. In spite of the many variants of models proposed in the literature, none of them accounts for one important feature of the battery dynamics, namely, the dependency on the frequency of current load profile. For a given average current value, current loads with different spectral distributions may have quite different impacts on the battery discharge. This is a very well-know issue in the design of hybrid energy storage systems, where different types of storages devices are used, each with different storage efficiency for different load frequency ranges. We propose a basic modification to a state-of-the-art model that incorporates this load frequency dependency, as well as a methodology to identify the frequency-sensitive parameters of the model from publicly available data (e.g., datasheets). The results show that frequency-agnostic models can significantly overestimate the battery state-of-charge, and that this effect is far from being negligible.