An experimental validation of the adoption of dc-dc converters for the impedance measurement in Li-Ion batteries

Abstract

Electrochemical Impedance Spectroscopy (EIS) is one possible technique to determine the State of Health (SOH) in Li-Ion batteries. This article describes some challenges involved in the implementation of EIS analysis in a battery charger. As an application example, some design issues on the control of power converters that can be used to perform the EIS analysis are addressed. The description focuses on several aspects, from the development of the measurement channels for current and voltage to the design of the perturbation signal control system. The device performances are tested in several conditions such as to determine the impedance of a singular Li-ion cell having 3.63 V and 2.6 Ah , but also in a small-scale battery pack having 25.2 V and 11.2 Ah, using different perturbation signals.

A Multiport Converter for Flexible Active Balancing in Li-Ion Batteries

“…Smart diagnostic techniques, such as electrochemical impedance spectroscopy (EIS), can be implemented by the proposed structure by controlling the current injected into the cell (e.g., injecting a sinusoidal current perturbation). Usually, the measure of Li-ion battery impedance requires an external current source to provide the perturbation signal [29], [30]. The proposed solution can perform the EIS without external sources or dc biases thanks to the bidirectional capability of each HB module.…”