Investigation of Broadband Excitation Signals for Online Battery Impedance Spectroscopy and Model Identification

Electrochemical impedance spectroscopy (EIS) is a particularly useful tool in modelling and characterization of battery cells, which in turn helps monitor the battery condition and estimate its state-of-health. In this work, a number of broadband excitation signals for fast, online battery EIS are investigated and compared. A DC/DC boost converter is then utilized in order to inject the battery with the different types of excitation signals, and the measured impedance spectra are then fitted into a fractional-order equivalent circuit model (ECM) of the lithium-ion battery. Superior performance is seen with the discrete-interval binary sequence (DIBS) signal which produces the best model fit, resulting in a 0.27mΩ root mean square error between the measured results and the fitted ECM.