Magnetic Materials and Components
Technical Dialogue Session
Devices and Components II
EMI filter design, frequency-dependent permeability, imaginary permeability
Compared with the flat permeability curve of ferrite cores up to several MHz, the permeability of nanocrystalline cores with a high initial value drops at only around 100 kHz. In addition, the imaginary permeability of nanocrystalline can provide a considerable impedance to achieve the noise attenuation compared with ferrite, being neglected in the inductance-oriented design approach. To achieve a more accurate design result, the paper proposes an impedance-based design approach with considering both frequency-dependent and imaginary permeability of nanocrystalline cores. The required impedance of a CM inductor is derived by the equivalent circuits at a specific frequency.