Design of an embedded electrochemical impedance spectroscopy for real-time systems

Reliable battery state estimation is critical for the safety and longevity of energy storage systems, yet traditional Electrochemical Impedance Spectroscopy (EIS) remains largely confined to laboratory settings due to its high cost and hardware complexity. This paper presents a low-cost strategy for integrating EIS into battery chargers as an embedded solution for real-time battery parameterization. The proposed EIS method employs an adaptive sampling frequency, acquiring data over just two cycles per frequency to minimize acquisition time while effectively mitigating spectral leakage using conventional windowing. The sampling frequency’s adaptability enables synchronous detection of discrete Fourier transform (SD-DFT), ensuring the same number of samples per frequency. A complex order fractional proportional resonant (COFPR) controller supports the high-frequency EIS control tracking requirements, outperforming traditional controllers by offering superior high-frequency tracking, reduced excitation regions, and preserved DC controllability. Integrating the COFPR controller within the same power converter and simple DC bias compensation, enabled by the adaptive sampling frequency, streamlines the design, simplifies operation, reduces the computational burden, and eliminates the need for frequency-specific controller selection. This combination of COFPR and SD-DFT enables seamless EIS implementation within battery chargers without requiring complex or dedicated systems, leveraging the existing DC-link. Simulations, experimentals and computational burden validation confirm the practicality and effectiveness of the proposed approach, demonstrating its potential for enhanced battery diagnostics on real-time embedded solutions.