Control of N87 Mn-Zn Ferrite Permeability Using Externally Applied Static Magnetic Field

This paper reports measurement results of N87 Mn-Zn ferrite's permeability response to externally applied static magnetic field. The measurements were conducted by applying magnetic field of a permanent magnet to a test magnetic component during usual ac excitation. Frequency dependencies of the complex initial permeability and respective loss tangent, as well as large signal square wave excited BH loops at single frequency, were taken under various configurations of the positioning between the magnet, the core under test and the excitation winding. The obtained results demonstrate strong dependency of both the real and imaginary parts of the initial permeability. At high frequencies the loss tangent gets lower. Control of the ferrite complex permeability and the usable frequency range of ferrites is achievable by variation of the strength of the external static magnetic field.