A Wideband Modeling Method for Magnetic Components Considering Strong/Weak Near-Field Coupling Characteristics

Abstract

Magnetic components in switching power supplies generate severe leakage electromagnetic fields, which not only affect the filtering performance of EMI filters but also may disrupt the normal operation of circuits. This paper first analyzes the mechanism of near-field leakage generated by magnetic components. It investigates the effect of frequency-dependent permeability on the self-parameters of these components and further explores how the self-parameters influence mutual parameters. By integrating both effects on near-field coupling, a wideband near-field coupling model for magnetic components is established, which accounts for the transmission characteristics of both magnetic and electric field coupling. Insertion loss is measured using a network analyzer and converted into Z-parameters to extract the values of equivalent inductance, equivalent capacitance, and equivalent resistance in the self-parameter module and mutual-parameter module. The near-field transmission characteristics of magnetic components under both strong and weak coupling scenarios are tested to verify the accuracy of the proposed wideband near-field coupling model, which exhibits good conformity in the frequency range from 100 kHz to 60 MHz. The results indicate that magnetic field coupling and electric field coupling dominate the near-field transmission characteristics of magnetic components in different frequency bands.