Nonparametric analysis of the short-term electrical response of Li-ion battery cells

In order to develop a complete dynamic model of a lithium ion (Li-ion) battery's electrical behaviour, which is suitable for virtual-prototyping of battery-powered systems, accurate estimation of the state of charge (SoC) and state of health (SoH) is required. This in-turn depends on the quality of the models which are used for the estimation of these quantities. Hence, even before proceeding towards the modelling step, it is important to fully characterize and understand the electrical behaviour of the battery over its full operating range, so that a flexible and accurate dynamic model can be developed. In this paper, a novel frequency domain non-parametric methodology is proposed to characterize the battery short-term electrical behaviour, in terms of: Presence of the non-linearities as well as the time-variations (non-stationary behaviour) over its full operating range. This information can later be used by battery modeller to decide on the modelling methodology.