Performance Evaluation of Inductive and Capacitive Couplers for Pulsed Current Injection

Pulsed current injection (PCI), as an important conducted susceptibility testing method, has been introduced in several standards. However, the selection of couplers for PCI tests has not been clearly specified, which leads to the fact that the injected electrical quantities by different couplers might be rather different and it is inadequate to inject the proper disturbance at the testing ports. So, it is of significance to evaluate their performance quantitatively and determine the usage scenarios for couplers. This article focuses on the quantitative performance evaluation of inductive and capacitive couplers including inductive ferrite-core clamps and capacitive coupling clamps. A distributed-parameter multiconductor transmission line (MTL) model has been proposed for couplers clamped on N wires. The validation test confirms the accuracy of the model in the bandwidth of PCI tests. The performances of an inductive coupler and a capacitive coupler are analyzed and compared based on MTL models. The selection criterion of the couplers is concluded as that a proper coupler should lead to higher time-waveform norms, which indicate possible nonlinear effects of the tested objects, such as the overcurrent, the turn-to-turn breakdown, and the component burnout.