Evaluation of Active Injection to Characterize Common-mode Equivalent Circuits

<p dir="ltr">Recently, researchers have proposed using Thévenin equivalent circuits to model the common-mode (CM) behavior of power converters. A convenience offered by Thévenin circuits is that they can be characterized using only terminal measurements and thus do not require evaluation of internal parasitic paths. In this research, the use of an active line impedance stabilization network (ALISN) is considered to perform circuit characterization. Within the ALISN, a bulk current injection (BCI) probe is placed on a shunt line connected to a converter under test. The probe is then used to provide an excitation to the converter wherein measurements within the ALISN can be used to establish differential- and common-mode impedances of the converter. An evaluation of a commercial BCI probe and matching injection source is performed to estimate the range of impedance that can be accurately characterized. For cases in which an ALISN is needed for high-power and high-voltage applications, approaches to test converters in a de-energized state are proposed.</p>