Online impedance measurement of operational batteries utilizing Sinc function signal injection via DC-DC power converter

This paper presents a novel method for the online impedance measurement of operational batteries that utilizes Sinc function signal injection via a DC-DC power converter. The Sinc function perturbation signal, with its multiple frequency components, enables simultaneous impedance measurement of the battery at various frequencies, thus ensuring high measurement efficiency. Additionally, the generation and injection processes for this perturbation signal are simple and straightforward. Its power spectrum, characterized by a uniform distribution and relatively high power content, enables precise measurements across the entire frequency range of interest. The paper extensively discusses the measurement principle and properties using the perturbation signal, followed by an analysis of the circuit topology to derive the transfer functions, and a simulation to examine the battery's responses under the perturbation signal. Finally, a case study using a 2.8 Ah 883860-size lithium polymer battery demonstrates the feasibility and accuracy of the proposed method.