Optimized perturbation technique for enhanced broadband impedance measurement in Lithium-ion batteries

Abstract

Battery impedance provides critical insights into the internal state and health of a battery, making accurate frequency-domain measurement essential for characterization and diagnostics. This paper addresses key challenges in battery impedance measurements and evaluates two existing perturbation approaches for broadband impedance measurements in lithium-ion batteries using the same perturbation signal for comparative analysis. A novel approach is proposed that divides the frequency range into multiple bands, each independently perturbed using optimized excitation signals tailored to the band. Statistical averaging is implemented to further enhance measurement precision. By concentrating perturbation energy within specific frequency regions, the method improves the signal-to-noise ratio and reduces variance and bias in the impedance response. Experimental results demonstrate that this technique extends the measurable frequency range and improves accuracy compared to conventional methods, offering significant advancements in battery diagnostics.