Permeability Macromodels for Magnetic Powder Materials Under DC Bias

Magnetic powder materials are often considered for inductors used in high-current applications due to their high saturation flux densities and good high-frequency performance. For the design and optimization of powder-based high-frequency inductors, it is important to consider permeability spectra with superimposed DC bias. To include those properties in system-level circuit simulations, compact macromodels are required. Therefore, this work proposes a black-box model and a phenomenological model, providing equivalent circuits for the permeability of magnetic material under DC bias. The accuracy of both models is investigated using measured permeability spectra of commercial powder core materials. Application examples are outlined to illustrate the benefits of those macromodels. It is demonstrated that the black-box model provides very accurate results over the entire range of parameters for all materials, while the phenomenological model in its present, simple form and gives satisfactory results only for selected magnetic materials, in the frequency range of interest.