New nanocrystalline materials for power electronics applications

New nanocrystalline materials for the applications in the power electronics systems are developed and tested. These materials are intended to be used in the magnetic circuits of switching-mode power supplies (SMPS). The aim was to achieve extremely low hysteresis and non-linearity in operating region resulting in increased efficiency and decreased weight and size whilst keeping low price of the high-power frequency converters for SMPS

Combined influence of shape and magnetocrystalline anisotropy on measured magnetisation curves of SiFe sheets

From the comparison of B(H) curves measured in SST and RSST on grain-oriented SiFe sheets with high anisotropy follows that the correlation between them is doubtful. It is mainly due to strong influence of the shape anisotropy in the case of SST interacting in complicated way, owing to nonlincarity, with the magnetocrystalline anisotropy. The results obtained in RSST which provides the possibility of controling VB are closer to the real situation in such magnetic circuits where the vectors B and H are deviated from the rolling direction. The aim of presented paper is to answer the question to which extend correlate the SST and RSST experimental results and to prove the assumption about the reason of discrepancies

An optimization of experimental data processing for the MAT method application

Magnetic adaptive testing (MAT) is a new method of magnetic non-destructive inspection of structural mechanical properties of magnetic construction materials. Principle of MAT consists in analysis of several magnetic properties I a wide range of input variables and to find the degeneration function with optimum correlation to inspected degeneration physical process. This involves processing of large amounts of experimental data. We present a new software tool for data processing based on application of various digital filters. A novel approach of statistical analysis and thresholding using masks was introduced to data analysis and thus qualitatively improving MAT optimisation process

The influence of particle size and substituent contents on the magnetic properties of Be or Cu substituted NiZn ferrites

Polycrystalline NiZn ferrites with the chemical formula (Ni0.3Zn0.7)1−xMexFe2O4 where Me being Be or Cu and x=0.05, 0.1 and 0.25 have been prepared by a ceramic method. Certain magnetic properties such as the coercivity Hc, initial permeability m i, real part of the complex permeability m’ and saturation magnetization Ms of the ferrites have been measured and discussed from the point of view of the substituting element type and contents as well as the average particle size

Structural and Magnetic Properties of Nano-Sized NiZn Ferrites

Structural and magnetic properties (such as e.g. size of crystallites, lattice parameter, magnetic susceptibility, Curie temperature, etc.) of nano-sized $Ni_{0.33}Zn_{0.67}Fe_{2}O_{4}$ ferrites have been studied. The obtained results demonstrated that the sintering temperature is an efficient and simple tool for controlling the size of crystallite particles, thus affecting the resulting magnetic properties. Straightforward relationship between the sintering temperature and the size of crystallites was found, meanwhile no other crystalline phases than the spinel one were detected by two independent analytic methods

Magnetic Properties of Ni0.3Zn0.7Fe2O4Ni_{0.3}Zn_{0.7}Fe_2O_4 Ferrites with Iron Ions Partly Substituted by Europium

This work is devoted to the study of the impact of the substitution of iron by Eu on the properties of magnetically soft $Ni_{0.3}Zn_{0.7}Eu_{x}Fe_{2-x}O_4$ ferrites aimed at enhancement of the knowledge related to the behavior of such materials in dependence on the amount of iron substitution. Our latest studies focused on the materials having similar chemical composition gave a hint of some possible approaches to manage the resulting magnetic properties in a precisely controlled way by the combination of several factors; choice of initial chemical composition of non-substituted ferrite, selection of substituted and substituting element, variations of final chemical composition, modifications of fabrication technology (sintering temperature and time), etc

Magnetic Properties of Yttrium-Substituted NiZn Ferrites

Polycrystalline NiZn ferrite doped with a small amount of $Y^{3+}$ ions and having the composition of $Ni_{0.42}Zn_{0.58}Y_{x}Fe_{2-x}O_{4}$, where x=0.00, 0.01, 0.02, 0.04, 0.06, 0.08 and 0.10, was analyzed. Specimens were prepared by the ceramic method. Thermo-magnetic analysis and evaluation of hysteresis loops parameters were chosen as main examination methods in this study. Various parameters, such as Curie temperature $T_{C}$, coercive field $H_{c}$, remanent magnetic flux density $B_{r}$, hysteresis loop area and amplitude/initial permeability were studied at low frequencies

Modelling of complex permeability in cores

In the numerical field analysis a problem that still remains is the development of magnetic parameter models that accurately represents the effect of magnetic anisotropy under complex magnetic conditions. Two modified approaches have been used for the calculation of complex permeability in oriented FeSi lamination. In the first approach pure relaxation processes have been accepted in model approximation and the hysteresis effects have been taken into account separately neglecting the relaxation. In the second approach, besides separated pure irreversible processes also mixed processes, i.e. relaxation and hysteresis mutually influenced are considered. In weak alternating field these irreversible processes have been represented by Rayleigh loop