Multi-purpose controllable electrochemical impedance spectroscopy using bidirectional DC–DC converter

In this paper, we propose a multi-purpose controllable electrochemical impedance spectroscopy (MP-cEIS) device for online and offline battery monitoring and testing during charge and discharge processes. The proposed MP-cEIS device is based on the widely used synchronous buck converter, with a low-cost and simple input filter to provide the bidirectional operation. It also includes a closed-loop feedback system to control the injection of the EIS excitation signal. For the control system design, an average model of the proposed MP-cEIS is derived. Two methods, based on H∞ and quantitative feedback theory (QFT), are presented for the design of a robust controller, which guarantees the stability and tracking of the excitation signal despite model uncertainties. The excitation signal in the proposed MP-cEIS is programmable. The performance of the proposed MP-cEIS is evaluated experimentally, with multi-sine and swept-sine signals, and the results are shown.