Krzysztof Chwastek

Identification of a hysteresis model parameters with genetic algorithms

The paper is concerned about the application of genetic algorithms to the estimation of magnetic hysteresis model parameters, based on the description of magnetization process proposed by Jiles and Atherton. The genetic algorithm approach has been applied to estimation of model parameters for two magnetic materials - a conventional non-oriented steel and a modern amorphous material. The errors between the modelled and experimental data points on M-H plane have been determined. The results have been compared with the results obtained with the previously proposed approach, based on direct search method. It has been proved that the genetic algorithm approach results in lower percentage errors. tage errors.

Modelling of dynamic hysteresis loops using the Jiles--Atherton approach

The article deals with the modelling of dynamic hysteresis loops. The modelling is carried out within the framework proposed by D. Jiles and D. Atherton. The dynamic effect of eddy currents is taken into account using G. Bertottis approach. A satisfactory agreement between the measured and the modelled dynamic hysteresis loops as well as the corresponding loss densities is obtained.

Modelling dynamic hysteresis loops in steel sheets

Purpose – The aim of the paper is to present a simple approach to modelling minor hysteresis loops in grain‐oriented steel sheets under quasi‐static and dynamic conditions. The hysteresis phenomenon is described with a recently developed hybrid model, which combines ideas inherent in the product Preisach model and the Jiles‐Atherton description. The dynamic effects due to eddy currents are taken into account in the description using a lagged response with respect to the input.Design/methodology/approach – It is assumed that some model parameters might be dependent on the level of relative magnetization within the material. Their dependencies could be given as power laws. The values of scaling coefficients in power laws are determined.Findings – A satisfactory agreement of experimental and modelled quasi‐static and dynamic hysteresis loops is obtained.Research limitations/implications – The present study provides a starting point for further verification of the approach for other classes of soft magnetic m...

AC loss density component in electrical steel sheets

This article proposes a new approach to the loss separation issue. The conventional loss separation into three components is abandoned. The dependence of the dynamic component of loss density versus frequency is assumed to be a power law. The model is verified for selected samples of nonoriented and grain-oriented steel.

Modelling magnetic properties of MnZn ferrites with the modified Jiles–Atherton description

Consideration of temperature and anisotropy effects in hysteresis modelling allows for tailoring the operation point of magnetic circuits. The recently modified Jiles–Atherton model has been extended to describe the hysteresis loops in MnZn ferrites for two temperatures below the Curie point. Anisotropy is modelled by a proper choice of the value of the quantum number J in the Brillouin function.

Sensitivity Analysis and Modeling of Symmetric Minor Hysteresis Loops Using the GRUCAD Description

This paper presents a predictive and easily implementable hysteresis model for ferromagnetic laminations subjected to various quasi-static magnetic loads. In this model, the description of magnetic hysteresis is based on the decoupling of the magnetic field strength in a reversible and irreversible part, unlike in the Jiles-Atherton model. Thereby, the source of problems originating in the assumption that total magnetization could be split into the reversible and the irreversible component is bypassed. It should be stressed that models based on field separation principles are consistent with the laws of thermodynamics. The presented model allows for a systematic parameter identification based on standard magnetic measurements. In this paper, the variation of model parameters on the shape of the modeled hysteresis loop is presented. Furthermore, parameter identified from the major loop are applied to model symmetric minor loops that are evaluated by comparison with measurements. The structure of the model enables an inclusion of eddy-current effects, and is ready for a further exploitation in the FE modeling of macroscopic devices.

Hysteresis loop as the indicator of residual stress in drawn wires

The paper investigates the possibility of using the magnetic method for non-destructive determination of residual stress in drawn wires. The change in residual stress for different processing speeds is reflected in the shape of hysteresis loop. A simple model for stress-dependent hysteresis, based on the concept of the effective field, is proposed. The effective field includes an additional term related to stress, in accordance with previous Jiles’ and Sabliks results. The presented description may be useful for technologists seeking a simple tool for predicting residual stress.

The effects of excitation conditions and annealing temperature on power loss in SMC cores

The paper considers the effects of excitation conditions (maximum induction, frequency) and annealing temperature on power loss dissipated in cores made of commercially available soft magnetic composites. The study has confirmed that the choice of annealing temperature has a significant impact on the magnetic properties of ready-made cores. It has been found that Somaloy 500 cores annealed at 450° C feature the lowest loss density in a wide range of excitation frequencies. The dependencies: total power loss versus frequency have been described using four alternative descriptions. The results indicate that the considered dependencies are equivalent and may be approximately described with a two-term formula of the form: Ptotal = Whyst f + a f 2 . Streszczenie. W pracy przedstawiono wplyw parametrow wymuszenia (maksymalna indukcja, czestotliwośc) oraz temperatury wyzarzania na straty mocy rozpraszane w rdzeniach z komercyjnie dostepnych kompozytow magnetycznych SMC. Stwierdzono, ze wybor temperatury wyzarzania ma istotny wplyw na wlaściwości magnetyczne gotowych rdzeni. Zaobserwowano, ze rdzenie z materialu proszkowego Somaloy 500 wyzarzone w temperaturze 450° C wykazują najnizsze straty w szerokim zakresie czestotliwości magnesowania. Zaleznośc strat calkowitych od czestotliwości opisano za pomocą czterech alternatywnych formul. Wyniki badan wskazują na fakt, ze rozwazane zalezności mogą byc potraktowane jako rownowazne i opisane za pomocą formuly dwuskladnikowej w postaci Ptotal = Whyst f + a f 2 . Wplyw parametrow wymuszenia oraz temperatury wyzarzania na straty mocy rozpraszane w rdzeniach z kompozytow magnetycznych SMC .

Hysteresis curves of a resistance spot welding transformer

Purpose – The aim of the paper is to provide a simple and reliable hysteresis model for prediction of magnetization curves of a resistance spot welding transformer (RSWT) core, operating in a wide range of flux densities and excitation frequencies.Design/methodology/approach – The hysteresis model considered in the paper is the T(x) description advanced by J. Takacs. Three options to extend the model to the dynamic magnetization conditions are considered. The excitation conditions differ from those prescribed by international standards.Findings – The quasi‐static Takacs model combined with a fractional viscosity equation similar to that proposed by S.E. Zirka outperforms other considered options. The effect of eddy currents may be considered as a disturbance factor to the frequency‐independent quasi‐static hysteresis loop.Research limitations/implications – The combined approach yields in most cases a satisfactory agreement between theory and experiment. For highest frequency considered in the paper (1 kH...

Loss separation in chosen grades of grain-oriented steel

This paper is aimed at providing a review of the possible approaches to model the dependence of power losses vs. frequency in grain-oriented steels. Two models are compared using representative datasets for grades of different thickness.