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This article focuses on a protection system from lightning indirect effects applicable to power converters for avionic applications. The case study considered in this article is a dc–dc pulsewidth modulation buck–boost converter protected by a metal oxide varistor and a series inductive blocking element. The converter is investigated when operated in normal operating conditions, under lightning indirect strokes without protection, and under lightning indirect strokes with protection. A numerical model of the system based on a finite-difference time-domain scheme is proposed. Validation of the system is performed through a comparison with experimental measurements and alternative numerical modeling techniques, showing the effectiveness of the blocking system and the accuracy of the proposed model. [ABSTRACT FROM AUTHOR]

The performance of ferrite core filters to suppress lightning induced fast transients in the avionic environment is discussed in this article. A dynamic model of a ferrite core filter has been formulated by the combination of a rate independent hysteresis model based on the Preisach theory, and a linear electrical network. The dynamic model is numerically implemented by a finite difference scheme in the time domain. The model is parametric with respect to the geometrical dimension of the ferrite core, which is useful in the design process. The combination of a ferrite core filter with a metal oxide varistor is considered in order to study the practical effect in terms of protection level, size of the core, and the lifetime of varistor. The pin injection tests procedure, reported in the specific standards for avionic diagnostic is simulated, and the predicted results are experimentally verified. [ABSTRACT FROM AUTHOR]

Rotational magnetizations of an Ni–Fe alloy are simulated using two different computer modeling approaches, physical and phenomenological. The first one is a model defined using a single hysteron operator based on the Stoner and Wohlfarth theory and the second one is a model based on a suitable system of neural networks. The models are identified and validated using experimental data, and, finally, an example of their application for a finite-element analysis is given. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a dynamic model of the electrical transformer suitable for the numerical prediction of the inrush currents due to the arbitrary initial excitation of a transformer after a switch-OFF. In particular, the proposed model can be helpful to control strategies to avoid a transient current overshoot, based on the prediction of the residual magnetic flux. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A magnetic medium can have different hysteresis losses when subject to a rotating field. We discuss the pertinent parameters that determine these losses and a method of identifying them. We discuss the effect of particle interaction, and isotropic and anisotropic media. [ABSTRACT FROM PUBLISHER]

The magnetic modeling of Si-Fe magnetic steels is presented in this paper. The modeling is based on a class of vector hysteresis operators recently introduced. The vector approach works without the additional manipulations and the corrections of the scalar case. The distribution of the probability function of the vector hysteresis operators is identified by a suitable set of magnetic measurements. Experimental verifications about the prediction of the model of some magnetization processes are presented. [ABSTRACT FROM AUTHOR]

This paper presents a micromagnetic study about the nonlinear properties exhibited by spin torque oscillators, implemented as nanoscale exchange biased spin-valves of elliptical cross-sectional area. The analysis is based on numerical simulations which also include the back-torque effect in the pinned layer. The external bias field is applied along the in-plane hard axis. Our results demonstrate that there exists a critical field at which the current dependence of the oscillation frequency changes passing from a "red shift" (typical of in-plane magnetization) to a "blue shift" (typical of out-of-plane magnetization). Such results are in qualitative agreement either with recent experiments and with an analytical non-linear theory which identifies the transition field as the field at which the non-linear frequency shift vanishes. In such condition, the generation linewidth exhibits a minimum, the phase noise is independent of the power noise, and the oscillation frequency is independent of both current and power. [ABSTRACT FROM AUTHOR]

A useful vector magnetic model must accurately simulate both the magnitude and direction of the magnetization when a magnetic medium is subjected to a linear or rotating applied field. Such a model has been recently presented as the Preisach-Stoner-Wohlfarth (PSW) model. The Preisach model computes the magnitude of the magnetization; the Stoner-Wohlfarth model computes the direction of the magnetization. These two models are combined into the PSW model. The PSW model is now initially implemented in a two-dimensional vector classical Preisach model. The model is computationally efficient since the magnetization angle is accessed for all applied fields from a single lookup table, which is generated by a one-time Stoner-Wohlfarth computation. [ABSTRACT FROM AUTHOR]

This paper deals with the diffusion of rotating electromagnetic fields into hysteretic materials. A simplified vector formulation based on a parallelogram hysteresis model has been investigated, in order to significantly reduce the computational effort. Vector saturation and loss properties are discussed. The whole simulation has been done by the use of a finite-element time-domain algorithm. [ABSTRACT FROM AUTHOR]

This paper introduces a simplified vector model based on the Preisach approach that intrinsically satisfies loss and saturation properties. It is able to reproduce isotropic and nonisotropic behavior. The main idea is to compute the magnetization vector in two steps independently, amplitude and phase. The first one is computed by means of a scalar Preisach model with a distribution depending on the angle of the applied field with respect to a fixed direction. The phase is computed by means of a phase diagram and a simple function that take into account the history of the angle between magnetization and applied field. The proposed formulation allows fast computation of rotational and alternative vector magnetization, the computational time is of the order of two times the scalar Preisach model. [ABSTRACT FROM AUTHOR]

This paper discusses the numerical implementation of a new vector hysteresis model, the radial vector model, introduced as general hysteresis vector model for both isotropic and anisotropic magnetic materials. The present implementation is a 2-D one that uses ellipses as critical surfaces. The results computed by the model, applied to some basic vector hysteresis configurations, are in agreement with experimental behavior. [ABSTRACT FROM AUTHOR]

In this paper, we present and discuss the use of a reduced Preisach vector model (RVPM) as a numerical tool for the analysis of the influence of the cut angle in the magnetic behavior of laminated Fe-Si steels. The model parameters can be deduced by measurements along the easy and hard axis, and the families of hysteresis loops and virgin curves for the same Si-Fe sheet, cut at different angles with respect to the rolling direction can be derived. In particular, we present a simplified identification procedure based on the assumption that the material is single-quadrant medium along the principal axes. Results seem to indicate that the hypothesis of factorizable Preisach function is not compatible with the real magnetic materials. [ABSTRACT FROM AUTHOR]

This paper deals with the characterization of dynamic loops shapes and losses in soft magnetic materials. An experimental and theoretical analysis has been done in order to describe static and dynamic hysteresis on soft ferrite cores. A parallelogram-loop-based hysteresis modeling is described and discussed. The possibility of the model to include vector hysteresis and the related properties are then discussed, with particular attention to the case of a rotating magnetic field into an isotropic and anisotropic medium. [ABSTRACT FROM AUTHOR]

Proposes an approach to examine magnetic losses of cylindrical cores of isotropic materials in a frequency domain. Identification of scalar parameters of the modified Preisach scalar model; Computation of the magnetic field-magnetic induction distribution; Remarks on the analysis of eddy currents losses versus frequency and computational accuracy.

Presents a numerical procedure capable of analyzing a nonlinear diffusion of an electromagnetic field into a hysteretic magnetic conductor half-space. Evaluation of surface impedance of hysteretic materials; Formulation of nonlinear impedance boundary conditions; Description of hysteretic behavior through a modified scalar Preisach model.

Discusses a technique for estimating the Preisach function of a soft magnetic material from symmetrical magnetizing process. Identification of the Preisach function; Complications in computing the Preisach function for soft magnetic materials; Use of symmetric remanence curve to obtain the Preisach function.

Proposes a method for identifying the parameters of the probability function of Preisach-based models for soft magnetic materials. Overview of the proposed identification procedure; Validation of the method; Conclusions.

Presents information on a study which described the Modified Scalar Preisach Model for modeling of the magnetic hysteresis in soft ferromagnetic materials. Identification of the modeling parameters; Numerical results; Conclusions.

Discusses the electro-thermal behavior of solid armatures in railguns. Integral approach in studying the behavior of solid armatures; Electro-thermal behavior of the armature derived by the numerical simulation.

Investigates the efficiency of equipotential and grounding systems with respect to an electrostatic discharge (ESD) event. Information on Finite-Difference in Time-Domain (FDTD) approaches; Three dimensional electromagnetic modeling of an ESD event; Numerical simulations and comparisons.

Presents a numerical model for the computation of the electromagnetic field produced by an Electrostatic Discharge(ESD), occuring in the vicinity of a system of conducting objects. Simplification model of the ESD; Numerical calculation of electromagnetic field based on the finite difference time-domain algorithm of Yee's space-time mesh; Numerical validation; Conclusions.

Discusses the proposed approach to the numerical analysis of the electromagnetic interferences(EMI) radiated by metallic grids, like the Faraday's cages, hit by a lightning stroke. Geometry of the problem and main assumptions; Numerical modeling for current density distribution computation inside the metallic grid; Computation of the electromagnetic fields radiated; Results of the computation; Conclusions.

Deals with the numerical analysis of the behavior of diffracting perforated shields, and in particular of honeycomb structures. Geometrical description and modelling of the perforated shield; Numerical algorithm; Computed results on the effectiveness and accuracy of the method; Conclusions.

Discusses the testing of an integral approach to numerically solve the equations of magnetohydrodynamics (MHD) flow of electromagnetic railgun plasma armatures, by comparison with a known and well tested differential approach. Analysis on differential approach; Three sets of dividing the MHD equations; Two computer codes of simulating the test; Results of the simulation; Conclusions.

Presents two different numerical analysis of the electromagnetic environment near railguns operating with plasma armatures. Modeling of the electromagnetic fields produced during the plasma arc ignition; Modeling of the electric and magnetic fields produced during the shot; Results of numerical analysis; Conclusions.