Crosstalk compensation for a rapid, higher-resolution impedance spectrum measurement

Crosstalk Compensation is an approach that enables rapid, higher-resolution impedance spectra measurements of energy storage devices. The input signal consists of a sum-of-sines excitation current that has a known frequency spread. The advantage of Crosstalk Compensation is that high resolution spectra can be acquired within one period of the lowest frequency while also including non-harmonic frequencies. The crosstalk interference at a given frequency can be pre-determined and assigned to an error matrix. The real and imaginary impedance can then be calculated based on the inverse of the error matrix and captured response. Analytical validation of Crosstalk Compensation was performed using a battery equivalent circuit model. Two different frequency ranges were simulated, and both indicated that a minimum step factor between frequencies should be 1.25 to reduce the error in compensating the captured response signal. For a frequency range of 1638.4–0.1 Hz, for example, a maximum of 45 frequencies should be included within the excitation signal to accurately acquire the impedance spectra at high resolution. A simplified derivation of Crosstalk Compensation and its corresponding analytical validation studies are discussed.