Analysis of volume distribution of power loss in ferrite cores

We present a technique to estimate the inhomogeneities of magnetic loss across the section of ferrite cores under ac excitation. The technique is based on two distinct calorimetric methods that we presented elsewhere. Both methods are based on the measurement of the rate of increase of the sample temperature under adiabatic condition. The temperature ramp is recorded either measuring the sample bulk resistivity or using a platinum probe pasted on the sample surface. As an example we apply the procedure to an industrial sample of Mn-Zn ferrite under controlled sinusoidal excitation with a peak induction of 50 mT in the range between 100 kHz and 2 MHz. The results are discussed by comparison with simulations of the dissipation field profile through the sample, calculated using a finite element method (FEM) code. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3536792]