Estimation of ripple and inductance roll off when using powdered iron core inductors

Magnetic cores like powdered iron cores have a variable permeability, which is dependent on the magnetic motive force of the inductor windings. When inductors are designed using such materials, the inductance varies as a function of the inductor current. This causes a non-linear current to flow through the inductor. In this paper, mathematical derivation of the inductancecurrent relationship is derived for such inductors. The model is applied for a KoolMmu(r) powdered iron core and the results are verified experimentally using an interleaved boost converter.