A. Faba

A General Vector Hysteresis Operator: Extension to the 3-D Case

This paper deals with the mathematical definition of a general vector hysteresis operator in 3-D, as an extension of previous papers where the theory has been limited to the 2-D case. Although the paper is mainly focused on magnetic hysteresis, the definitions and the results reported can be applied to any general physical phenomenon that exhibits hysteresis. We show here the main general properties of the general hysteresis operator in 3-D.

A Benchmark Problem of Vector Magnetic Hysteresis for Numerical Models

In this paper, we present a benchmark problem for the validation of numerical models of vector magnetic hysteresis. The problem geometry and the measurement system are described. The materials considered are both oriented grain (OG) and not OG Si-Fe steels. A series of experimental data about magnetic field and magnetic induction loci under rotational magnetization are presented with the corresponding magnetic losses. The measured data can be useful as a reference for the numerical models testing, comparison, and development. In addition, we propose here a comparison of the experimental data with the numerical results computed using a vector hysteresis model based on the extension of the Preisach model in 2-D.

Surface field measurements in vector characterization of Si-Fe magnetic steel samples

In this work we discuss some procedures to increase the accuracy in the measurement of the magnetic field strength using Round Rotational Single Sheet Tester RRSST frames. The procedures are discussed jointly with the use of different magnetic field probes, such as flat coils and Hall sensors, and with a suitable shielding geometry. Experimental comparison between different methods and a discussion about the results is presented.

Numerical Modeling of Hysteresis in Si-Fe Steels

In this paper, we discuss the numerical modeling of hysteresis in magnetic steels with oriented and nonoriented grain. The modeling is fully 3-D, but it is applied here to typical 2-D magnetic problems. Starting from a vector generalization of the Preisach model, we introduce here the concept of an operative magnetic field, function of the state of magnetization of the material. This operative field is introduced to reproduce with more accuracy the peculiar behavior of Si-Fe steels approaching the saturation state. The properties of the model are discussed and some examples are reported.

Energy and Losses in Vector Thermal Aftereffect Model

This work deals with some energy properties of a vector thermal aftereffect model, recently presented. The model can compute magnetization and magnetic losses using an extension in 2-D of a Preisach-type approach. Some properties of the model are presented and discussed. An experimental validation is also included.

Numerical Implementation of the DPC Model

This paper discusses the numerical implementation of a new vector hysteresis model, called the Della Torre, Pinzaglia and Cardelli (DPC) model, introduced as general hysteresis vector model for both isotropic and anisotropic magnetic materials. The present implementation is a 2-D one that uses any kind of hysteron described by the DPC formulation. Here some examples of numerical computation using Stoner-Wohlfarth-type hysterons are presented. The results computed by the model, applied to some basic vector hysteresis configurations, are in agreement with experimental behavior and model properties.

Analysis of a Unit Magnetic Particle Via the DPC Model

This paper presents a discussion of the properties and the behavior of an unit magnetic particle as calculated by the DPC (Della Torre, Pinzaglia and Cardelli) model. The general mathematical expressions of the vector field generated by the unit magnetic particle are derived in a special regular parametric coordinates system. It is shown that, in a special case, the DPC model leads to the same results as in the Stoner-Wohlfarth dealing with the physics of an ellipsoidal, single-domain, uniaxial magnetic particle. Some numerical examples for a possible use of the DPC model in the analysis of nanomagnetic samples are presented.

Theoretical Considerations of Magnetic Hysteresis and Transformer Inrush Current

This paper presents an application of a hysteresis model that is coupled to an equivalent network for the calculation of the inrush current due to an arbitrary excitation of a transformer after a fault. The approach proposed, although using several simplifying assumptions, seems promising in order to calculate the optimal time to close the circuit after a fault.

Magnetization dependent vector model and single domain nanostructures

In this paper we present a phenomenological approach computing the behavior of a cobalt particle by the Della Torre–Pinzaglia–Cardelli (DPC) model. The identification of the model is realized using a suitable numerical procedure and a set of data obtained using a micromagnetic numerical model based on Brown’s equations. In order to simplify the identification, a class of hysterons, which describes the magnetization process of a single domain in agreement with the Stoner and Wohlfarth theory, is used. The accuracy of the reconstructed magnetization cycles using the DPC model and the save of the computation time with respect to the micromagnetic numerical model are shown.

Mathematical Modelling of Magnetic Hysteresis in Exchange-Bias Spin Valves

In this work we present a physical-related model of vector hysteresis for magnetic simulation of nanometric structures. The mathematical formulation, based on a generalization of the Preisach and Stoner-Wohlfarth models, is very simple and elegant. The numerical implementation is very easy and the computation time required for the simulations is extremely fast. However the accuracy is not comparable with the codes based on the micromagnetic theory, but it is sufficient for the use as preprocessing of more accurate and more complex methods, in order to speed up the convergence. In this paper the model identification is performed for a nanoscale spin valve using the data generated by a 3D micromagnetic code.