Modeling and Increasing the High-Frequency Impedance of Single-Layer Mn-Zn Ferrite Toroidal Inductors With Electromagnetic Analysis
Yiming Li, Shuo Wang
Abstract
This article first investigates the equivalent parallel capacitance (EPC) and equivalent parallel resistance (EPR) due to the electromagnetic field inside the Mn-Zn ferrite toroidal cores of the inductors with a single-layer winding based on electromagnetic theory. From the investigation, the effects of core's cross-sectional shape and number of winding turns on the EPC and EPR are explored. A stacked core structure was studied to increase the inductor's high-frequency (HF) impedance for electromagnetic interference suppression. The article further investigated the EPC due to the electric field energy in the space between winding turns, and between the winding turns and the core. The effect of the number of winding turns on total EPC was also explored. The technique to achieve high HF impedance was proposed with an optimal number of winding turns. Both simulations and experiments were conducted to validate the developed theory and techniques.