A Novel Single-Probe Setup for Multifrequency Simultaneous Measurement of In-Circuit Impedance

The single-probe setup (SPS) based on the inductive coupling approach is a promising candidate for in-circuit impedance measurement of an energized electrical system due to its noncontact characteristics and simple configuration. However, the conventional SPS performs the measurement with a frequency-domain measuring instrument via stepped swept-sine excitation. It measures in-circuit impedance at only single frequency at a time while sweeping across frequencies of interest, which is not only inefficient but also not fast enough to capture in-circuit impedance with time-variant characteristics. To overcome these limitations, this article proposes a novel SPS with a time-domain measuring instrument via multisine excitation. The proposed SPS can perform multifrequency simultaneous measurement of in-circuit impedance without direct electrical contact. By combining it with a short-time Fourier transform algorithm, in-circuit impedance with time-variant characteristics can be captured. Experimental case studies validate the capability and accuracy of the proposed SPS.