Jan Szczygłowski

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.

Losses scaling in soft magnetic materials

Purpose – The paper presents an application of the scaling theory in a description of energy losses in soft magnetic materials in order to improve an agreement between measurements and theoretical models.Design/methodology/approach – The scaling theory allows the description of energy losses by a generalized homogenous function, which depends on scaling exponents α, β and amplitudes Γ(n). The values of the scaling exponents and amplitudes were estimated on the basis of measurement data of total energy losses.Findings – The main findings of the paper are: the linear relationships between the scaling exponents α and β, the data collapse of energy losses and the scaling laws for asymptotic exponents of energy losses derivatives.Research limitations/implications – The origin of the data collapse and the relationship between the scaling exponents will be the subject of further research with the aid of renormalization group methodPractical implications – The paper could be useful both for device designers and r...

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...

Energy losses in Fe-based and Co-based amorphous materials

Abstract It was shown in our experiments, that the dependence of excess losses on induction and frequency in amorphous materials (CoFeMnMo)77 (SiB)23 and in Fe78 (SiB)22 does not follow the dependencies resulted from Pry-Bean and Bertotti’s models. In this paper, the experimental results and their non-standard statistical analysis of the function describing the dependence of excess losses on frequency and induction are reported. The function was identified from a wide class of functions by means of an analysis of transformation of random variables, the so-called Box’s and Cox’s transformation. The function was so chosen, that the observation vector P, after Box–Cox transformation, had a normal distribution and its expected value was a linear function of B and f transformations, where B was the induction vector and f was the frequency vector. The logarithmic transformation for (CoFeMnMo)77 (SiB)23 material transforms P into Pexc=0.553·B1.51·f 1.41·e′ and for Fe78 (SiB)22 one into Pexc=1.23·B2·f1.25·e′. The results may be useful for the analysis of magnetic circuits during design and when in use in real electrical equipment.

Modeling Hysteresis Loops of SMC Cores

Hysteresis modeling plays an important role for the designers of magnetic circuits. The paper considers the effect of processing temperature on magnetic properties of SMC cores. The hysteresis loops of the SMC cores are described using two recent modifications of phenomenological models.

A correlation of magnetic properties with material density for soft magnetic composite cores

Purpose – The purpose of this paper is to examine the relationships between processing conditions and magnetic properties of cores made of Soft Magnetic Composite (SMC) Somaloy 500. Design/methodology/approach – The effects of compaction pressure and hardening temperature may be combined considering SMC density. This quantity may be chosen for optimization of properties of ready-made cores. In order to describe hysteresis loops the phenomenological model based on hyperbolic tangent transformation is applied. Findings – SMC density affects substantially the shape of hysteresis loop. The paper provides a number of charts useful for checking how the parameters of the hysteresis model are affected. Research limitations/implications – The present study considers just one composition of the SMC and one type of lubricant. Future research shall be devoted to verification of the approach on a wider class of SMCs. Practical implications – Material density may be a relevant quantity in optimization of magnetic prope...

Soft magnetic materials for energy-efficient electric motors

The paper presents different types of soft magnetic materials, which may be used for manufacturing of magnetic cores of energy-efficient electric motors. The properties of these materials are compared and their prospective influence on the efficiency of electric motors is discussed.

The Effect of Compacting Pressure on Power Loss in a SMC

The paper considers the effects of compacting pressure and the working parameters (maximum flux density, excitation frequency) on power loss dissipated in a soft magnetic composite core. The effects may be efficiently described with simple power laws . The description has been verified using commercial SMC cores. The proposed dependencies are in a good agreement with experiment.

Magnetic Composites in Electric Motors

Magnetic composites are manufactured as magnetic powder bonded by dielectric material, which bond and insulate powder grains. Magnetic composites are applied in electric machines due to their favorable magnetic and mechanical properties as well as possibility of tailoring their physical properties. The paper is a review of soft and hard magnetic composites, their internal structure, properties, and advantages resulted from their application on magnetic circuits of electric motors.

Scaling in Magnetic Materials

The chapter presents applications of the scaling in several problems of magnetic materials. Soft magnetic materials (SMMs) and soft magnetic composites (SMCs) are considered. Application of scaling in investigations of problems, such as power losses, losses separation, data collapse of the losses characteristics and modelling of the magnetic hysteresis, is presented. The symmetry group generated by scaling and gauge transformations enables us to introduce the classification of the hysteresis loops with respect to the equivalence classes. SMC materials require special treatment in the production process. Therefore, algorithms for optimization of the power losses are created. The algorithm for optimization processes is based on the scaling and the notion of the pseudo-equation of state. The scaling makes modelling and calculations easy; however, the data must obey the scaling. Checking procedure of statistical data to this respect is presented.