High-frequency behavior of power inductor windings using an accurate multiconductor transmission line model: Input impedance evaluation

This research and tutorial paper is the second part of a work dedicated to the analysis and computation of the electromagnetic behavior of inductor windings operating at high-frequency regimes-a critical issue for very fast transient overvoltage studies. The inductor winding, Wound around a ferromagnetic core, containing a total number of N dielectric coated cylindrical turns. is modeled by using a multiconductor transmission line (MTL) approach (proximity effects being accounted) whose constitution and characterization was presented in a former paper. In the present work, we make use of the R, G, L, and C Constitutive matrices of the structure in order to develop a modal analysis technique-based formulation aimed Lit the evaluation of the winding's input impedance in the frequency-domain. Results obtained show that the input impedance critically depends not only on the number of layers of the winding but also, and, more importantly, on the frequency, where resonance phenomena play a key role. Frequency-domain analysis is complemented with simulation results in the time-domain that clearly illustrate how critical and sensitive the system response can be under minute changes of the winding's excitation Current. Copyright (c) 2007 John Wiley & Sons, Ltd.