Load- and Source-Based Impedance Measuring Methods: Comparing Concepts and Structural Limitations in a Laboratory Environment

The time- and frequency-variant impedance is gaining importance as a necessary parameter to describe and determine systems and devices. There is a multitude of use-cases ranging from structural health monitoring to PLC applications. Many measuring concepts have been developed and were implemented in prototypes and first commercial solutions. In regard to the power-flow, all active concepts may be divided into either source-based systems, which actively feed a current into a measuring setup, or load-based approaches, which switch passive loads and therefore draw a current from the setup. The main objective of this paper is to compare and distinguish the two basic concepts within a controlled laboratory environment by switching between a constant and a sub-periodically influenced load scenario.