A Novel Lithium-Ion Battery Impedance Fast Measurement Method With Enhanced Excitation Signal

Online battery impedance acquisition is of increasing interest due to its valuable information for state estimation and fault diagnosis. The pseudorandom sequence (PRS) can significantly mitigate the required time cost, yet suffers from an insufficient signal-to-noise ratio. Motivated by this, this article proposes a novel series-connected dual pseudorandom sequence for enhancing the signal power content in all frequency ranges, which notably improves the robustness of broadband impedance acquisition against interference. A weighted bilateral impedance filter is further carried out on a semilogarithm scale to process the measurement data, which effectively compensates for the noise-induced biases and enables a nearly unbiased result. Experimental studies verify the proposed framework by comparing it with the conventional PRS method in terms of accuracy and robustness under various states of charges, ambient temperatures, and aging status of the batteries.