Li-ion Batteries Parameter Estimation Using Converter Excitation and Fusion Methods

This paper proposes a fusion method to estimate the low frequency impedance of Lithium-Ion batteries by using excitation signals. The proposed excitation is delivered by the converter used for the interface of the battery. The fusion method is conducted in two steps. Firstly, the impedance is estimated by using a frequency method known as vector fitting. Despite its high accuracy, it has a moderate computational burden that makes it difficult to use in real-time application running on the embedded systems often used for battery and converter control. For that reason, in a second stage, recursive least squares algorithm will be used for the parameter estimation in real-time. The discussion includes not only the methods description and testing, but also the effects of the data used for the estimation (terminal current and voltage) as well as the discretization method used for the digital implementation. The proposal is validated by simulation and with preliminary experimental results.