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Article
Publication date: 12 November 2021

Leysmir Adriana Millan Mirabal, Oualid Messal, Abdelkader Benabou, Yvonnick Le Menach, Loic Chevallier, Jean-Yves Roger and Jean-Pierre Ducreux

The purpose of this study is to explore the effect of the demagnetizing field in the Epstein characterization of grain-oriented electrical steels through a finite element…

Abstract

Purpose

The purpose of this study is to explore the effect of the demagnetizing field in the Epstein characterization of grain-oriented electrical steels through a finite element method (FEM) simulations.

Design/methodology/approach

A 3D finite element simulation has been realized to represent the parallel and X-stacking configurations in the Epstein frame. The numerical results have been compared with experimental measures.

Findings

In a parallel configuration, the measured induction is actually the one in the material, whereas the resulting magnetic field differs from the applied one (in magnitude and angle) due to the shape anisotropy (demagnetizing field). In X-stacking configuration, the resulting magnetic field is close to the applied magnetic field (and then the supposed excitation field in the Epstein frame), whereas the magnetic induction has deviated from the axis of the strips.

Originality/value

Both stacking configurations (parallel and cross) of the Epstein frame are analyzed by three-dimensional finite element simulation.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 16 November 2010

Francisc Bölöni, Abdelkader Benabou and Abdelmounaïm Tounzi

Electrostatic microelectromechanical systems are characterized by the pull‐in instability, associated to a pull‐in voltage. A good design requires an accurate model of…

Abstract

Purpose

Electrostatic microelectromechanical systems are characterized by the pull‐in instability, associated to a pull‐in voltage. A good design requires an accurate model of this pull‐in phenomenon. The purpose of this paper is to present two approaches to building finite element method (FEM) based models.

Design/methodology/approach

Closed form expressions for the computation of the pull‐in voltage, can provide fast results within reliable accuracy, except when treating cases of extreme fringing fields. FEM‐based models come handy when high accuracy is needed. In the first model presented in this paper, the FEM is used to solve the electrostatic problem, while the mechanical problem is solved using a simplified Euler‐Bernoulli beam equation. The second model is a pure FEM model coupling the electrostatic and mechanical problems iteratively through the electrical force. Results for both scalar and vector potential formulations for the FEM models are presented.

Findings

In this paper a comparative study of simple pull‐in structures is presented, between analytical and 3D FEM‐based models. A comparison with analytical models and experimental results is also realized.

Research limitations/implications

The coupling between the electrostatic and mechanical problem in the presented approaches, is iterative. Therefore, to improve the accuracy of the presented model, a strong coupling is needed.

Originality/value

In the presented FEM‐analytical model, the electrostatic problem is solved in both, scalar and vector electric potential formulations. This allows defining an upper and a lower limit for the electrostatic force and consequently for the pull‐in voltage.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 8 May 2009

Jean‐Yves Roger, Emmanuel Vrignaud, Thomas Henneron, Abdelkader Benabou and Jean‐Pierre Ducreux

Coreplates in large generators may suffer from local short circuits. An accurate analysis is required to avoid these failures and detect them when occurring. The purpose…

Abstract

Purpose

Coreplates in large generators may suffer from local short circuits. An accurate analysis is required to avoid these failures and detect them when occurring. The purpose of this paper is to develop a lamination stack model compliant with interlamination default analysis.

Design/methodology/approach

An electromagnetic model should account for the eddy‐current in the lamination stack. To avoid the modelling of the insulation between the steel sheets, the authors propose to introduce a condition on the fields applied between each sheet. In the case of electric fault between several sheets, the conducting domain, i.e. the sheets, is not simply connected. Then, T‐Ω formulation must be adapted to solve such problem.

Findings

The model allows to account for thin plates, insulating layers and electrical faults in electromagnetic modeling of core plates. This study leads to a first evaluation of eddy current losses in steel laminations with defaults.

Research limitations/implications

The present study does not take into account thermal effects. The next step will consist in a magneto‐thermal computation. Thus, an electromagnetic finite element software must be coupled with a thermal one. An other improvement will rely on the study of actual situation in order to evaluate the accuracy of industrial sensors and to compare with measurements.

Originality/value

The paper develops a lamination stack model compliant with interlamination default analysis. As far as the authors know, this is the first study on 3D electromagnetic modeling.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 September 2004

Abdelkader Benabou, Stéphane Clénet and Francis Piriou

In this communication, the Preisach and Jiles‐Atherton models are studied to take hysteresis phenomenon into account in finite element analysis. First, the models and…

Abstract

In this communication, the Preisach and Jiles‐Atherton models are studied to take hysteresis phenomenon into account in finite element analysis. First, the models and their identification procedure are briefly developed. Then, their implementation in the finite element code is presented. Finally, their performances are compared with an electromagnetic system made of soft magnetic composite. Current and iron losses are calculated and compared with the experimental results.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 July 2013

Mircea Fratila, Abdelkader Benabou, Abdelmonaïm Tounzi and Maxime Dessoude

Pulse width modulated (PWM) inverters are widely used to feed induction motors for variable speed applications. The use of PWM power supplies induces additional magnetic…

Abstract

Purpose

Pulse width modulated (PWM) inverters are widely used to feed induction motors for variable speed applications. The use of PWM power supplies induces additional magnetic losses in the magnetic circuit of the electrical machine. The aim of this paper is to present a novel analytical approach to account for these losses.

Design/methodology/approach

The methodology proposed here consists in identifying the analytical method with a static Preisach hysteresis model. The Preisach model was validated by comparing it with measurements obtained from an Epstein frame. Then, the results obtained with this approach were compared with a basic analytical method that is widely used.

Findings

The authors' model provides a fast way for estimating the minor loop iron losses introduced by static convertors. They compared the proposed model with another analytical model (J. Lavers model) for different wave forms. One can observe that the J. Lavers model overestimates the iron losses introduced by the non‐centred minor loops.

Originality/value

In this paper, an improved analytical model is presented which estimates the non‐centred minor loop iron losses. In order to do a precise estimation of the iron loss introduced by the minor loops, the authors' model takes into account the position and the size of the minor loop. The proposed model is identified from a static Preisach model.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 July 2013

Mircea Fratila, Rindra Ramarotafika, Abdelkader Benabou, Stéphane Clénet and Abdelmonaïm Tounzi

To take account of the uncertainties introduced on the magnetic properties during the manufacturing process, the present work aims to focus on the stochastic modelling of…

Abstract

Purpose

To take account of the uncertainties introduced on the magnetic properties during the manufacturing process, the present work aims to focus on the stochastic modelling of iron losses in electrical machine stators.

Design/methodology/approach

The investigated samples are composed of 28 slinky stators, coming from the same production chain. The stochastic modelling approach is first described. Thereafter, the Monte‐Carlo sampling method is used to calculate, in post‐processing, the iron loss density in a PMSM that is modelled by the finite element method.

Findings

The interest of such an approach is emphasized by calculating the main statistical characteristics associated to the losses variability, which are Gaussian distributed for A and Ω formulations.

Originality/value

The originality of the approach is due to the fact that the global influence of the manufacturing process (cutting, assembly, …) on magnetic properties of the considered samples is taken into account in the way of computing the iron losses.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 14 August 2007

Jean V. Leite, Abdelkader Benabou, P.A. da Silva, N. Sadowski, Thomas Henneron, Stéphane Clénet, P. Kuo‐Peng, Francis Piriou and N.J. Batistela

The magnetic field strength measurement in a rotational single sheet tester (RSST) is quite difficult to achieve. In fact, flux leakage perturbs the field sensors as well…

Abstract

Purpose

The magnetic field strength measurement in a rotational single sheet tester (RSST) is quite difficult to achieve. In fact, flux leakage perturbs the field sensors as well as the homogeneity in the sample area. This paper seeks to present a 3D finite element (FE) model of an RSST taking into account a vector hysteresis model. The use of such model allows analyzing with accuracy the magnetic behavior of the system.

Design/methodology/approach

A vector hysteresis model, which is based on a general vectorization of the scalar Jiles‐Atherton model, is incorporated in a 3D FE code, with vector potential formulation.

Findings

The vector hysteresis model is validated by comparison with rotational experimental results. A good agreement is observed between calculations and measurements.

Originality/value

This paper shows that a classical scalar hysteresis model can be extended to take into account the magnetic vector behaviour and can be included in a 3D FE code. The methodology for the hysteresis including in the FE formulation is shown. This is useful for the design and analysis of an RSST prototype, improving the measurement techniques.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 8 May 2009

Jean V. Leite, Abdelkader Benabou and Nelson Sadowski

Although the original Jiles‐Atherton (J‐A) hysteresis model is able to represent a wide range of major hysteresis loops, in particular those of soft magnetic materials, it…

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Abstract

Purpose

Although the original Jiles‐Atherton (J‐A) hysteresis model is able to represent a wide range of major hysteresis loops, in particular those of soft magnetic materials, it can produces non‐physical minor loops with its classical equations. The purpose of this paper is to show a modification in the J‐A hysteresis model in order to improve the minor and inner loops representation. The proposed technique allows the J‐A model representing non‐centred minor loops with accuracy as well as improving the symmetric inner loops representation.

Design/methodology/approach

Only the irreversible magnetization component is slightly modified keeping unchanged the other model equations and the model simplicity. The high‐variation rate of the irreversible magnetization, which causes the non‐physical behaviour of minor loops, is limited by introducing a new physical parameter linked to the losses. Contrarily to other modifications of the original model found in the literature, the previously knowledge of the magnetic field waveform is not needed in this case.

Findings

The modified hysteresis model is validated by comparison with experimental results. A good agreement is observed between calculations and measurements. The modified model retains the low‐computational effort and numerical simplicity of the original one.

Originality/value

This paper shows that a classical scalar hysteresis model can be suitably used to take into account the minor loops behaviour and be included in a finite element code. The methodology is useful for the design and analysis of electromagnetic devices under distorted flux patterns.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 7 September 2012

Juliana Luísa Müller, Raphaël Romary, Abdelkader Benabou, Thomas Henneron, Francis Piriou, João Pedro Assumpção Bastos and Jean‐Yves Roger

Interlaminar short circuits in turbo generator stators can lead to local damage of the iron core. The purpose of this paper is to model an interlaminar short circuit…

Abstract

Purpose

Interlaminar short circuits in turbo generator stators can lead to local damage of the iron core. The purpose of this paper is to model an interlaminar short circuit diagnosis test on an existing structure.

Design/methodology/approach

This work presents the modeling of short‐circuited laminations in a stator yoke of a turbo‐generator. A 3D finite element model, associated to a homogenization technique, is used to calculate the short‐circuit current. The diagnosis test known as El Cid has been modelled as well.

Findings

Calculation results are compared with the experiment. The same tendency has been observed both in experimental and numerical results.

Research limitations/implications

Additional calculations may be performed (parametric studies) in order to investigate El Cid measuring under different conditions (different material properties, fault position, size), which may lead to a better interpretation of the results.

Practical implications

Modelling of short circuit diagnosis tests under different conditions may help with the interpretation of measuring results, predicting the fault size/seriousness and location. So, only the concerned parts of the stator have to be disassembled and repaired/rebuilt.

Originality/value

It is not easy to model numerically a structure with a short circuit inside, since different dimensions are involved: the fault and the varnish between laminations are much smaller than the stator itself. Thus, homogenization techniques have been used to model the lamination stack region. The combination of this technique with the modelling of the El Cid test constitutes a tool to study this kind of fault and calculate its severity and location in a stator.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 9 September 2013

Rindra Ramarotafika, Abdelkader Benabou and Stéphane Clénet

Classically the magnetic material models are considered with a deterministic approach. Nevertheless, when submitted to the fabrication process, the magnetic core…

Abstract

Purpose

Classically the magnetic material models are considered with a deterministic approach. Nevertheless, when submitted to the fabrication process, the magnetic core properties are negatively impacted and may be subject to variability during the process. This variability can be of such importance that the performances of the final device (electrical machine) will also present a noticeable variability. The aim of this research is to develop a stochastic model of the magnetic behaviour law of slinky stators used in claw pole generators. The proposed methodology is general and can be applied to other physical properties of electrical devices.

Design/methodology/approach

The approach is based on a methodology that uses experimental data and a statistical description of the magnetic properties. To that end, a set of samples issued from the same chain of assembly is considered. The hysteresis model is then developed by accounting for the parameter correlation structure.

Findings

It is found that the magnetic hysteresis properties of the studied samples can be modelled by means of statistical tools applied to the parameters of the hysteresis model. The dependency of the parameters can also be accounted for a more accurate modelling.

Originality/value

The paper proposes a statistical approach and a methodology that are applied to the hysteresis modelling accounting for the variability of the magnetic properties. The developed model can be further used in a numerical tool to represent the impact on the performances of electrical devices that are subject to the fabrication process variability.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 5
Type: Research Article
ISSN: 0332-1649

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