Analysis of a Mn–Zn Ferrite Bundle EMI Suppressor Using Different Suppressing Principles and Configurations

A novel round cable electromagnetic interference (EMI) suppressor comprising a bundle of Mn-Zn ferrite tubes was realized using different principles of suppressing, such as direct suppressing, inverting/suppressing, transform/inverting suppressing, and transform/short circuited secondary suppressing. Different primary to secondary configurations were realized for each suppressing principle and characterized in the EMI frequency region. The results obtained for different bundle configurations were compared with known commercial round cable ferrite suppressors and the initial bundle configuration made of a half turn wire through the central ferrite tube of the bundle. The results obtained for different principles and configurations were correlated in order to optimize the electromagnetic coupling between primary and secondary circuits. The values such as maximums of impedance Z_m, frequency of maximum impedance Fm and suppressing range Δ_f around F_m calculated on 0.707 Z_m were defined as the main parameters for each configuration. Certain correlations were noticed between impedance Z_m and frequency F_m changes. Finally, the realized configurations were considered as devices suitable for EMI suppressing applications.