Abdelkader Benabou

• PhD - Habilitation
• Professor (Associate) - Hab. at University of Lille Nord de France

High-power electrical machines often utilize clamping structures composed of various materials with specific geometric dimensions to secure the stator laminations. These structures are exposed to end-region magnetic flux, which induces eddy currents, leading to significant power losses that reduce the machine’s efficiency. This study systematically...

This paper explores the implications of nonlinear anisotropic behavior models on the simulation of magnetic losses in a toroidal core made of a conventional Grain-Oriented Electrical Steel (GOES) within a finite element method (FEM) simulation environment. GO laminations are commonly used to improve the efficiency of electrical machines, but their...

Magnetostrictive thin films, exhibit significant utility as functionalization materials for Surface acoustic wave sensors designed for magnetic field measurements. This research investigates the influence of annealing under vacuum and magnetic field at various temperatures on the magnetic properties of the FeCo/TbCo2 thin film and therefore on the...

The aim of this study is to introduce a new technique for characterizing the magnetostrictive behavior of non-oriented ferromagnetic steel sheets using miniaturized wireless surface acoustic wave sensors (SAW). Unlike conventional optical and electromechanical techniques, this type of sensor offers advantages such as on-board capability, high-tempe...

Surface Acoustic Wave (SAW) sensors represent a prominent technological avenue for quantifying mechanical stress-induced deformations. Nonetheless, the integration of these Micro-Electro-Mechanical Systems (MEMS) sensors remains an complex challenge. Consequently, a common approach within a multitude of research involves the utilization of a adhesi...

The load cell is an indispensable component of many engineering machinery and industrial automation for measuring and sensing force and torque. In this paper, we propose to investigate a force sensor design combining Surface Acoustic Wave (SAW) strain sensor with binocular load cell structure. For this purpose, we use a binocular test body instrume...

In this study, we conduct a comprehensive investigation to enhance the performance of shear surface acoustic wave (SAW) magnetic sensors. We explore the interaction between SAW and a nickel film deposited on ST-cut quartz in a delay line configuration. The nickel film, measuring 2 mm in width and 100 nm in thickness, undergoes vacuum annealing at...

This paper deals with a combined experimental/numerical approach to identify the degradation profile of the magnetic properties at the cutting edge of mechanically cut electrical steels. Using a dedicated magnetic measurement device combined with a specific magnetic characterization protocol and mechanical hardness measurements, the impacted distan...

Grain-Oriented Electrical Steels (GOES) are widely used in transformers to increase energy efficiency while reducing the volume and weight of such transformers. These GOES are characterized by their strong anisotropy, which leads to different magnetic properties (behavior law and iron losses) depending on the strength and the direction of the appli...

Surface Acoustic Wave (SAW) sensors represent a prominent technological avenue for quantifying mechanical stress-induced deformations. Nonetheless, the integration of these Micro-Electro-Mechanical Systems (MEMS) sensors remains an complex challenge. Consequently, a common approach within a multitude of research involves the utilization of a adhesi...

This paper deals with the temperature-dependent modelling of iron losses in the context of magnetic ageing of electricals steel used in high power electrical machines. First, two electrical steel sheet grades were heat treated at three temperatures in order to study the ageing effect evolution as a function of temperature. Results show a significan...

The performance and energy efficiency of electro-mechanical converters are strongly bound to the properties of their magnetic cores. The latter are mostly made from stacked laminations of soft magnetic materials, such as Fe3%Si, which limits the core geometry design. However, when complex geometries are required, usually forging processes may be em...

The manufacturing processes of electrical machines may lead to significant degradation of the magnetic properties of their magnetic core (stator, rotor) performances and, as a consequence, to a decrease of their energy efficiency. While the effects of some processes (cutting, welding …) are widely discussed in the literature, this is not the case w...

The magnetic behavior of a lamination stack made of grain-oriented electrical steel (GOES) is investigated under non-conventional 3D magnetic flux excitations. An experimental demonstrator has been designed to study a normal orientation of the magnetic flux path, with regard to the lamination plane, combined with different in-plane orientations of...

This study proposes the complete design of a dynamic measurement system of mechanical deformation. The final objective concerns the remote monitoring of mechanical stresses in electrical machines in order to address the issues of Industry 4.0 and predictive maintenance. The work carried out in this study concerns the design, fabrication and charact...

Nondestructive testing (NDT) of industrial steel products is commonly used to detect defects such as cracks using among other methods, electromagnetic techniques. When properly calibrated, these NDT can be adapted to evaluate the mechanical properties of steels. It is especially of prime importance when rigorous quality control must be achieved for...

This paper deals with the analysis of the magnetic properties degradation following an industrial impregnation process of electrical steels employed in stators of large generators. First, the impregnation process is studied directly on industrial stators to emphasize the significance of the process effect. Then, to have a controlled approach of the...

This paper describes the relations between microstructure, mechanical properties, and electromagnetic behavior of carbon steel wires submitted to different thermomechanical treatments. The electrical resistivity and bulk magnetic properties are determined through resistivity measurements down to 2 K and magnetic hysteresis loop measurements. In add...

Nowadays, additive manufacturing of metallic materials is most often carried out using expensive and complex tools that leave the user with limited control and no possibility of modification. In order to make the printing of metal parts more accessible to small structures but also better suited for academic research, the use of a mixture of thermop...

The need for electrical machines is growing in a wide range of applications nowadays, such as for energy production, automotive, marine, and medical equipment, etc. The reliability, efficiency, performance and operational safety are always critical issues, which implies that the monitoring and analysis during the operation of the equipment need to...

In high power electrical machines, the leakage magnetic flux due to end windings induces eddy currents in clamping devices. However, it is quite difficult to quantify these losses. In order to study the effect of different clamping materials and the impact of the magnetization direction, an experimental mock-up composed of a stator and a clamping p...

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 Epst...

This article deals with the modelling of iron losses due to the magnetic ageing of electrical steels used in energy conversion devices. This phenomenon is the consequence of irreversible mechanisms in the material which can be triggered by the operating temperature of electrical devices. At first, an experimental study is carried out at 180° C in o...

Regularly used in power transformers, grain-oriented (GO) steels are also usually chosen for the manufacturing of the stator cores of hydro and turbo-generators. These steels are renowned for their high magnetic performances in the rolling direction (high permeability and low magnetic losses). Nevertheless, in a turbo-generator where GO steels are...

Robustness and reliability of modern synchronous motors require an accurate design of the permanent magnets (PM) while accounting for the motor operating conditions (demagnetizing field, temperature). In this paper, the important attribute of a PM non-linear demagnetization model within a finite element method (FEM) simulation environment is clearl...

The quality of a local physical quantity obtained by the numerical method such as the finite element method (FEM) attracts more and more attention in computational electromagnetism. Inspired by the idea of goal-oriented error estimate given for the Laplace problem, this work is devoted to a guaranteed a posteriori error estimate adapted for the qua...

16MnCr5 steel parts were additively manufactured by laser powder bed fusion in order to investigate the effect of microstructure on electromagnetic properties. As process parameters have a direct impact on the obtained microstructure, different conditions were used to manufacture samples on which magnetic and electrical tests were conducted. The ob...

This paper deals with the experimental investigation of the effect of impregnation process on the normal magnetization curve and iron losses of electrical steels. To address this issue, several laminated toroidal magnetic circuits have been designed to characterize the magnetic properties with the flux metric method. The first configuration conside...

In this paper, a finite element (FE) modeling of the punching effect on the magnetic properties of electrical steel sheet is carried out. For that, the modified anhysteretic Sablik model is applied together with the plastic strain distribution obtained from a punching process simulation performed using the software ABAQUS. First, a synchronous elec...

In this paper, the magnetic ageing of a bulk forged non-annealed magnetic core, used in claw pole synchronous machine, is investigated. The study is carried out by characterizing the material properties of two groups of samples subjected to a thermal ageing at 180 °C that corresponds to the maximum operating temperature of the claw pole rotor. The...

During electrical machine manufacturing, the process may induce plastic mechanical strains, especially in the magnetic core. However, magnetic properties are highly sensitive to the material mechanical state. Thus, the performances of electrical machines, which also rely on the magnetic material properties, are often deteriorated. This paper propos...

In this paper, the vector extension of the Jiles-Atherton hysteresis model is modified to predict both alternating and rotational field strength variations observed in a nonoriented silicon steel sheet. The model parameters are changed to be functions of the magnitude and direction of flux density, and the anhysteretic magnetic characteristics are ide...

In this article, an experimental procedure is presented to handle magnetic measurements under uniaxial tensile stress reaching the plastic domain. The main advantage of the proposed procedure is that it does not require an additional magnetic core to close the magnetic flux path through the studied sample. The flux flows only in the sample, and no...

During the operation of Claw Pole (CP) machines, and for some operating loads, the magnetic core temperature can reach 180 °C in some hot spots. As a consequence, the core electromagnetic properties may considerably change, impacting the machine performances. In such a case, a deep knowledge of the electromagnetic behavior as a function of the temp...

In this paper, we propose a method to identify the magnetostrictive behavior of electrical steel sheet submitted to a mechanical loading. The technique relies on the use of a magneto-mechanical model including the magnetostrictive phenomenon, namely the anhysteretic Jiles-Atherton-Sablik (JAS) model, and experimental macroscopic stress dependent ma...

In this work, we investigate in Fe-Si laminations the core-loss coefficients variation with the flux density within the loss statistical approach framework. We find that the dynamical core-loss coefficients can be linked with the differential permeability defined from the low frequency normal curve. We interpret these variations as the fingerprint...

This paper presents a novel method for demagnetization fault detection in permanent magnet synchronous machine (PMSM). Demagnetization fault is a common problem existing in PMSM which deteriorates the machine performance and can lead to serious subsequential machine damages. Unlike the most popular method based on the analysis of the machine curren...

In this paper, the anhysteretic Sablik model is identified from measurements and implemented in a finite element code. The model takes into account the effect of the plastic deformation through the dislocation density and thus enables to account for the degradation of the magnetic properties. A new model for magnetostriction is proposed and impleme...

We investigate the effect of magneto-mechanical and magneto-crystalline anisotropy in a test application by coupling a multiscale magneto-mechanical model with a finite element method. This first application is composed of a cylindrical conductor surrounded by a ring composed of a non oriented FeSi3% steel sheet which contains 396 representative gr...

Magnetic parts are usually composed of a stack of electrical steel laminations to reduce the eddy current losses. However, for cost reasons or for specific applications the magnetic core can be made from massive steel and thus manufactured with adapted processes such as forging. Such process may lead to inhomogeneous and degraded magnetic propertie...

High operating temperatures modify the magnetic behavior of ferromagnetic cores which may affect the performance of electrical machines. Therefore, a temperature dependent material model is necessary to model the electrical machine behavior more accurately during the design process. Physics-inspired hysteresis models, such as the Jiles-Atherton (JA...

High operating temperatures modify the magnetic behavior of ferromagnetic cores which may affect the performance of electrical machines. Therefore, a temperature dependent material model is necessary to model the electrical machine behavior more accurately during the design process. Physics-inspired hysteresis models, such as the Jiles-Atherton (JA...

This paper reports on performances of high permeability grain oriented electrical steel when used in association with power electronic switching devices. Loss measurement results obtained from the Epstein test, using sinusoidal or various PWM voltages in medium frequency range, show that for both studied thicknesses (HGO 0.23mm and HGO 0.18mm), com...

The stray load losses in electrical machines represent a non-negligible contribution of the total losses and are a key point for an accurate evaluation of the energy efficiency of the considered device. In this paper, a methodology using the 3-D finite element (FE) modeling approach and a posteriori loss calculation is presented for the estimation...

This paper presents an efficient method to calculate the magnetic forces on bodies in contact. The forces are computed through local application of the Virtual Work principle on degenerated airgap elements. The results from this method are compared with those from another software and validated with measurements on a permanent magnet setup. Not onl...

This paper deals with the calculation of iron losses in a turgenerator using a magnetodynamic Finite Element (F.E.) Analysis accounting for the eddy currents in the damper bars. Two iron loss models, based on the Berttoti’s decomposition approach, are compared in the post-processing step of a F.E. calculation. The numerical model of the studied sys...

This paper presents an efficient method to calculate the magnetic forces on bodies in contact. The forces are computed through local application of the virtual work principle on degenerated airgap elements. These results are compared with those from different models and validated with measurements on a permanent magnet setup. Not only is this techn...

The stray load losses in electrical machines represent a non-negligible contribution of the total losses and are a key point for an accurate evaluation of the energy efficiency of the considered device. In this paper, a methodology using the 3-D finite element (FE) modeling approach and a posteriori loss calculation is presented for the estimation...

The performances of electrical machines depend highly on the behavior of ferromagnetic materials. In some applications, these materials operate under DC polarization, i.e. when the magnetic field oscillates around a DC bias. In that condition, it is required to know the incremental permeability which characterizes the magnetic behavior of the mater...

For electromagnetic applications the microstructure and the final mechanical state are key parameters. These can be obtained by a judicious choice of the material, a particular design like laminated steels but also through the determination and the mastering of the fabrication process. This present paper contains a brief introduction to electromagn...

The magnetic properties of the ferromagnetic cores and the resistance of conductors are severely affected by the high operating temperatures in modern electrical machines. These temperature effects must be taken into account in the electrical machine design process to predict their performance, accurately. In this work, we have proposed a simple mo...

A physics based approach is presented to predict the magnetic behavior of electrical steels under different temperatures. The approach is applied for the temperature range experienced by ferromagnetic materials in an electrical machine during its operation. The B-H loops were measured for 35WW300 non-oriented electrical steel at different values of...

An improved dynamic hysteresis model is proposed for the prediction of hysteresis loop of electrical steel up to mean frequencies, taking into account the skin effect. In previous works, the analytical solution of the diffusion equation for low frequency (DELF) was coupled with the inverse static Jiles-Atherton (JA) model in order to represent the...

This paper deals with the iron loss estimation in a 1MVA hybrid excitation synchronous generator, using finite element analysis. The iron loss computation is performed with a post-processing method using the Fourier transform of the flux density waveforms. The magnetic state of the numerical model is validated with an instrumented prototype. An exp...

In electrical machines, knowing the electrical conductivity is of importance for the eddy current calculation, especially when massive iron parts are involved. Generally the conductivity is measured on samples of raw materials with simple geometries. Indeed, a simple geometry is suitable for applying an analytical approach to deduce the electrical...

The stray load losses (SLLs) in electrical machines represent a nonnegligible contribution of the total losses and a key point for an accurate evaluation of the energy efficiency of considered device. In this paper, one aspect of these SLLs, the end-region leakage fluxes and losses, is investigated and considered for the case of a high-power cage i...

The switching of the power semiconductors in static converters is the main source of electromagnetic interferences (EMI). To meet with electromagnetic compatibility standards, it is necessary to reduce the level of the conducted emissions. This reduction can be achieved by different techniques including the EMI filters whose design is mainly based...

A framework for the finite element implementation of the formulas of local and global electromagnetic forces is presented. The theoretical framework, based on the Lie derivative, is applicable to 2-D and 3-D problems in the presence of arbitrary materials. The numerical properties of the proposed implementation, in terms of accuracy and convergence...

Two current probes are designed with the appropriate magnetic material in order to make impedance measurements in High Frequency (HF) using the Current Injection Method (CIM). These probes are then used to measure the commonmode impedance of power converters in real-operating conditions. The characterization of this impedance is required for a corr...

The magnetic material when designing EMI filter determines the inductance value and the parasitic elements that influence the insertion loss effectiveness of the filter. Moreover, the EMI filter characterization is usually realized at low power levels (low current and low voltage). When the EMI filter is subjected to higher currents through its coi...

The stray load losses represent a non-negligible contribution to the total losses in electrical machines. This paper investigates a contribution to these losses in the case of a non-skewed squirrel cage induction motor, namely the zig-zag flux. The study is performed at no-load, locked-rotor and load conditions for an induction machine with differe...

p>La mesure de la conductivité électrique est classiquement réalisée sur des échantillons de géométrie simple à partir desquelles la grandeur d'intérêt peut être aisément déduite. Lorsqu'il n'est pas possible d'extraire des échantillons respectant ces critères géométriques, dans le cadre d'une étude non-intrusive par exemple, d'autres approches doi...

NdFeB permanent magnets (PMs) are widely used in high performance electrical machines, but their relatively high conductivity subjects them to eddy current losses that can lead to magnetization loss. The Finite Element (FE) method is generally used to quantify the eddy current loss of PMs, but it remains quite difficult to validate the accuracy of...

This paper presents a study on iron loss estimation for a solid rotor induction motor fed by pulsewidth modulated supply. The iron losses are often determined using an a posteriori method that can lead to more or less important deviations, compared with measurements, depending on the used models and implementation techniques. The methodology propos...

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 (ele...

Two current probes, based on the current injection method, are designed with appropriated high frequency magnetic material. These probes are used to measure the common-mode impedance of power converters in real-operating conditions. The characterization of this impedance is of importance for the EMI filter design. In this paper, a simple formulatio...

When modeling a system subject to uncertainties, a fundamental aspect is the stochastic modeling of the input parameters of the model. Several calculation and analysis steps have to be considered, and can be found in the literature. In this paper, after presenting such steps, these are applied for the modeling of the variability of the magnetic beh...

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 chai...

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/a...

This paper discusses the reliability of a novel constitutive approach to model the magnetically assisted dry cutting of steel. The magnetic force combined with the mechanical force components, was found to be responsible for the perturbation observed in the primary shear angle. This perturbation is considered the basis of the analytical development...

Permanent magnets are commonly used in electromechanical energy conversion devices, especially in permanent magnet synchronous machines (PMSM). When designing such devices, it is necessary to take account for the operating conditions of the permanent magnets. Ideally, the operating point of the magnet lies on a linear reversible demagnetization cha...

Improvement of the magnetic performances of soft magnetic composites (SMC) materials requires to link the microstructure to the macroscopic magnetic behavior law. This can be achieved with the finite-element method using the geometry reconstruction from images of the microstructure. Nevertheless, it can lead to large computational times. In that co...

To take account of the uncertainties introduced on the soft magnetic materials properties (magnetic behavior law, iron losses) during the manufacturing process, the present work deals with the stochastic modeling of the magnetic behavior law B-H and iron losses of claw pole stator generator. Twenty-eight samples of slinky stator (SS) coming from th...

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...

The passive magnetic ferrite components used in EMI filters have a complex magnetic permeability (CMP) which varies with frequency. The CMP in frequency range from 150 kHz to 30MHz is not given by manufactures. Moreover, measurement techniques require some specific size and shape of sample to measure CMP of ferrites. Common application of these pas...

Manufacturing processes may introduce a significant variability on the magnetic properties of claw pole generator stators. The present work deals with the analysis of two groups of stator samples. The first group is composed of 28 slinky stators (SS) and the second group is composed of 5 stators, manufactured using laser cut stacked laminations (SL...

Manufacturing processes may introduce a significant variability on the magnetic properties of claw pole generator stators. The present work deals with the analysis of two groups of stator samples. The first group is composed of 28 slinky stators (SS) and the second group is composed of 5 stators, manufactured using laser cut stacked laminations (SL...

The Non-Intrusive Spectral Projection (NISP) method is widely used for uncertainty quantification in stochastic models. The determination of the expansion of the solution on the polynomial chaos requires the computation of multidimensional integrals. An automatic adaptive algorithm based on nested sparse grids has been developed to evaluate those i...

This paper deals with a stochastic approach to model the pull-in voltage in a microelectromechanical system (MEMS) beam structure. Two nonintrusive stochastic techniques are used: a sampling method, based on Monte-Carlo simulations and a polynomial chaos expansion (PCE) approach. The deterministic model solves an electro-mechanical problem using a...

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...