Simon Steentjes

Advanced Iron-Loss Estimation for Nonlinear Material Behavior

The aim of an optimal design of electrical machines requires the accurate prediction of iron losses for various operating points. For this purpose different iron-loss models have been proposed which intent to describe the loss inducing effects. The most used iron-loss prediction formulas are either physically based, but nevertheless only valid for linear material behavior at low frequencies and low magnetic flux densities, or grounded on a pure mathematical description of the material behavior, that is not more than interpolated measurements. This paper presents a modified loss equation with semi-physically based parameters as well as a first try to explain the nonlinear loss component.

Iron-Loss Model With Consideration of Minor Loops Applied to FE-Simulations of Electrical Machines

The accurate prediction of iron losses in soft magnetic materials for various frequencies and magnetic flux densities is eminent for an enhanced design of electrical machines in automotive applications. For this purpose different phenomenological iron-loss models have been proposed describing the loss generating effects. Most of these suffer from poor accuracy for high frequencies as well as high values of magnetic flux densities. This paper presents an advanced iron-loss formula, the IEM-Formula, which resolves the limitation of the common iron-loss models by introducing a high order term of the magnetic flux density. Furthermore the IEM-Formula is extended in order to include the influence of higher harmonics as well as minor loops. In line with this a detailed study of minor loop loss behavior is presented. Exemplarily, the iron-loss formula is utilized to calculate the iron losses of a permanent magnet synchronous machine for the drive train of a full electric vehicle.

Advanced iron-loss calculation as a basis for efficiency improvement of electrical machines in automotive application

The accurate prediction of iron losses of soft magnetic materials for various frequencies and magnetic flux densities is eminent for an enhanced design of electrical machines in automotive applications. For this purpose different phenomeno-logical iron-loss models have been proposed describing the loss generating effects. Most of these suffer from poor accuracy for high frequencies as well as high values of magnetic flux densities. This paper presents a comparison of the common iron-loss models to an advanced iron-loss formula. The proposed IEM-Formula resolves the limitation of the common iron-loss models by introducing a high order term of the magnetic flux density. Exemplarily, the iron-loss formula is utilized to calculate the iron losses of an induction machine for the drive train of a full electric vehicle.

Iron Loss Calculation in Steel Laminations at High Frequencies

This paper proposes a model for the computation of iron losses in steel laminations accounting simultaneously for magnetic hysteresis and eddy currents. The proposed model is well suited for finite element implementation and relies on a consistent thermodynamic background. The focus of this paper is particularly set on a systematic and accurate identification of material parameters from standard dc measurements (Epstein frame, single-sheet tester). Once identified, those material parameters can be used to obtain quantitative predictions of iron losses at higher frequencies and in the presence of higher harmonics. The model and the identification process are validated against measurements for a M235-35 A electrical steel over a wide range of field intensity and frequencies.

An Application-Oriented Approach for Consideration of Material Degradation Effects Due to Cutting on Iron Losses and Magnetizability

The decrease in magnetic permeability and increase of local hysteresis loss in the vicinity of lamination edges originating from the cutting process need to be accounted for during the design of electrical machines. A flexible method is needed, which is able to account for different degradation profiles due to different cutting techniques. This paper presents a quantitative analysis of the impact of material degradation on iron losses and magnetizability due to guillotine shear and CO2 laser cutting for non-oriented electrical steels.

Semi-physical parameter identification for an iron-loss formula allowing loss-separation

This paper presents a semi-physical parameter identification for a recently proposed enhanced iron-loss formula, the IEM-Formula. Measurements are performed on a standardized Epstein frame by the conventional field-metric method under sinusoidal magnetic flux densities up to high magnitudes and frequencies. Quasi-static losses are identified on the one hand by point-by-point dc-measurements using a flux-meter and on the other hand by extrapolating higher frequency measurements to dc magnetization using the statistical loss-separation theory (Jacobs et al., “Magnetic material optimization for hybrid vehicle PMSM drives,” in Inductica Conference, CD-Rom, Chicago/USA, 2009). Utilizing this material information, possibilities to identify the parameter of the IEM-Formula are analyzed. Along with this, the importance of excess losses in present-day non-grain oriented Fe-Si laminations is investigated. In conclusion, the calculated losses are compared to the measured losses.

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.