Impedance Modelling of Common Mode Ferrite Chokes using Transmission Line Theory

An impedance model, based on transmission line (TL) theory, is introduced for common mode ferrite chokes. The proposed model takes into account the geometrical properties of the choke, the distribution of electromagnetic fields within the core material and the impact of the measurement setup. The validity of the model was tested through numerical simulations. As a practical application, the model was applied to estimate the complex permeability of MnZn and NiZn cores from impedance measurements, resulting in a range of values compatible with those reported in other works.