Martin Petrun

Iron-Loss and Magnetic Hysteresis Under Arbitrary Waveforms in NO Electrical Steel: A Comparative Study of Hysteresis Models

This paper presents a comparative study of different static hysteresis models coupled to the parametric magneto-dynamic model of soft magnetic steel sheets. Both mathematical and behavioral as well as physically based approaches are discussed with respect to the ability to predict the dynamic hysteresis loop shape and iron loss under arbitrary excitation waveforms. Both current- as well as voltage-driven excitation cases are evaluated. The presented analysis discusses and points out advantages and limitations of the majority of the well-known static hysteresis models. In this way, it supports the selection of adequate hysteresis models for the specific application, i.e., smooth excitations, distorted flux waveforms, transients, or steady-state regimes. Comparisons against measurements for a M400-50A electrical steel over a wide range of magnetic flux density and frequencies for both sinusoidal and arbitrary excitations are analyzed. In the analysis hysteresis loop shapes, power losses as well as NRMS errors of individual loop sections are compared.

A Parametric Magneto-Dynamic Model of Soft Magnetic Steel Sheets

This paper deals with a new analytical parametric magneto-dynamic model of a thin soft magnetic steel sheet (SMSS). The interdependence of the magnetic field and eddy currents inside such an SMSS is calculated by dividing the sheets into an arbitrary number of slices. Using an adequate number of slices, the magnetic field and eddy currents are described piece-wise uniformly across the SMSS for a given excitation dynamics. Dynamic hysteresis loops for arbitrary excitations can be calculated using the proposed model. The calculated results are validated by the measurements on a non-oriented SMSS.

Power Loss Calculation Using the Parametric Magneto-Dynamic Model of Soft Magnetic Steel Sheets

This paper deals with the fundamental theoretical background of a 1-D parametric magneto-dynamic (PMD) model, which analytically solves the interdependence of the magnetic field and macroscopic eddy currents inside a thin soft magnetic steel sheet (SMSS). Furthermore, the loss calculation using the discussed model is presented, where instantaneous powers due to static hysteresis and induced eddy currents, as well as their power loss distributions across the SMSS thickness are calculated. The calculated results are validated by measurements on a non-oriented SMSS using sinusoidal excitations within wide frequency and magnetic flux density ranges.

1-D Lamination Models for Calculating the Magnetization Dynamics in Non-Oriented Soft Magnetic Steel Sheets

This paper presents 1-D dynamic magnetization models of non-oriented soft magnetic steel sheets that can be expressed as simple systems of ordinary differential equations. The discussed models take into account the dynamic effects on magnetization due to eddy currents and hysteresis inside such sheets and differ in the way the coupled Maxwell equations with hysteresis are solved. The presented modeling approaches include finite-difference schemes of different accuracies, various magnetic equivalent circuits (MECs), including a recent approach to eliminate the deficiencies of classical MECs, and a mesh-free approach. The different modeling approaches are analyzed and compared in terms of mathematical structure, implementation work, spatial discretization, and accuracy, where both voltage- and current-driven versions are investigated.

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.

Evaluation of Iron Core Quality for Resistance Spot Welding Transformers Using Current Controlled Supply

This paper reflects a newly developed method for evaluation of iron core quality for resistance spot welding (RSW) transformers. The classical methods for determination of the iron core quality are mostly based on a sinusoidal excitation. The proposed method is based on corresponding excitation by hysteresis controlled current in primary winding under no load operation, whereas consequently the primary current changes between its maximum and minimum value. Therefore, the operation point during the test is defined by the maximum magneto motive force (mmf) of the magnetic circuit. The tested iron core that reaches higher value of the magnetic flux density with the same maximum mmf, has lower average magnetic resistance and it is categorized as a better one, for the discussed RSW application. Furthermore, the value of the input reactive power is considered as an additional indicator for evaluation of the iron core quality. The proposed method is fully verified with numerical computations and laboratory measurements. The main advantage of the proposed method is that no extra equipment is required when testing the RSW systems.

Usage of a Simplified and Jiles–Atherton Model When Accounting for the Hysteresis Losses Within a Welding Transformer

The proposed paper deals with a nonlinear dynamic model of a welding transformer, where the effects of hysteresis losses are accounted for by the simplified method and by the inverse form of the Jiles-Atherton hysteresis model. Both models have been modified in such a way that they can be used when the magnetically nonlinear characteristic of the entire device is determined experimentally. The aforementioned characteristics are given in the form of approximation polynomials. For defining magnetically nonlinear characteristic and both the Jiles-Atherton hysteresis model and the simplified model, an optimization procedure based on the differential evolution is applied for obtaining the parameters of applied approximation polynomials. The main goal of this paper is to evaluate both discussed models regarding their suitability to be included into dynamic model of a welding transformer used in the optimization of the entire resistance spot welding system. The evaluation focuses on achieved accuracy and computational effort required to implement the discussed models.

Magnetization Dynamics and Power Loss Calculation in NO Soft Magnetic Steel Sheets Under Arbitrary Excitation

This paper deals with the analysis of a 1-D magneto-dynamic model (MDM) of soft magnetic steel sheets (SMSSs) under arbitrary excitation conditions. In the presented analysis, the MDM is coupled with the static hysteresis model proposed by Tellinen. The coupled model of SMSSs is evaluated using measured excitation voltages as well as measured excitation currents directly as the model input variables, where both excitation cases are compared and evaluated versus measurements. The calculated results show a good agreement with the measurements. Based on the presented analysis properties, advantages, and flexibility of the MDM model as well as the limitations of the presented coupled model are pointed out, where guidelines for an improved coupling are also given.

Effects of saturation and hysteresis on magnetisation dynamics: Analysis of different material models

Purpose – The purpose of this paper is to provide a comprehensive analysis of different material models when observing the magnetisation dynamics and power losses in non-oriented soft magnetic steel sheets (SMSSs). Design/methodology/approach – During the analysis four different magnetic material models were used for describing the static material characteristics, which characterised the materials’ magnetisation behaviour with increasing accuracies: linear material model, piecewise linear material model, non-linear H(B) characteristic and the static hysteresis material model proposed by Tellinen. The described material models were implemented within a parametric magneto-dynamic model (PMD) of SMSSs, where the dynamic responses as well as power loss calculations from the obtained models were analysed. Findings – The momentous influences of various levels of detail on the calculation of dynamic variables and power losses inside SMSS with non-uniform magnetic fields were elaborated, where various static mate...

Determining the Parameters of a Resistance Spot Welding Transformer Using Differential Evolution

This paper deals with determining the parameters of a resistance spot welding (RSW) transformer dynamic model. To obtain an efficient, accurate, and reliable dynamic model of an electromagnetic device, accurate determination of its models parameters is crucial. In regard to an RSW transformer, determining of the dynamic models parameters presents a big challenge. This paper presents a new methodology for determining such parameters, which can be used where other methods are not applicable or they give inaccurate results. It is based on a stochastic optimization algorithm called differential evolution (DE). Using the presented dynamic model of the device, the parameters of the model are determined by DE in such a way that the deviation between the measured and the calculated values is minimal.