bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of ferromagnetic thin sheets magnetization
Authors: Cauffet G. , Coulomb J.L. , Guerin S. , Chadebec O. , Vuillermet Y. 
Published: January 2008

PurposeThis paper aims to present the use of magnetic gradient, and magnetic potential measurements in the specific case of magnetization identification for a thin sheet. Usually, induction measurements are only used.Design/methodology/approachAfter a brief description of the magnetic gradient and magnetic scalar potential notions, methods to calculate them are presented and validated. These two kinds of measurements are tested for a numerical identification case. Then, virtual measurements can be generated and used for inverse problem resolution. Advantages of using induction, magnetic gradient or magnetic potential measurements are then discussed.FindingsA previous method to solve inverse problem based on induction measurement has been increased by the capability of using other kind of measurements. A numerical approach has allowed to validate the use of magnetic gradient or magnetic scalar potential measurement as information sources.Originality/valueUsually, induction measurements are only used. Inversion resolution using other kind of measurements than the induction can be made. An experimental validation has been done for gradient measurements.
Coupling of analytical and numerical methods for the electromagnetic simulation of permanent magnet synchronous machines
Authors: Schöning M. , Hameyer K. 
Published: January 2008

PurposeTo reduce the computational costs for electromagnetic simulations of permanent magnet synchronous machines maintaining a high accuracy.Design/methodology/approachAn analytical model is introduced regarding multiple designs of permanent magnet synchronous machines. This electromagnetic model is coupled to a numerical simulation. Thereby, the advantages of both computational methods are combined by parameterizing the analytical model to the numerical solution. This results in a high‐efficient analytical model with the accuracy of the numerical simulation. The results of the analytical model are compared to measurements of a permanent magnet synchronous machine. Various machine modifications are simulated to evaluate possible limitations of the analytical model.FindingsIt can be stated, that a once parameterized analytical model achieves a high accuracy. Furthermore, geometric variations can be applied without the need of a new parameterization through a numerical simulation. Only changing the permanent magnet height or the air gap height results in a significant deviation and a new numerical simulation is recommended.Research limitations/implicationsOnly measurements for machines up to 5 kW were available. In consequence, the model is only validatet in this range.Practical implicationsWith the presented analytical model, an electromagnetic design of a permanent magnet synchronous machine can be performed very time efficient achieving accurate results. Furthermore, optimization studies can be performed with low‐computational costs.Originality/valueThe introduced analytical model can be parameterized by a numerical simulation. The numeric simulation process and the parameterization are performed automatically according to the data calculated by the analytical model. Measurements demonstrate the effectiveness and the limitations of the model.
On the use of PML for the computation of leaky modes
Authors: Ould Agha Y. , Zolla F. , Nicolet A. , Guenneau S. 
Published: January 2008

PurposeThe purpose of this paper is to present a complete analysis of leaky modes within a microstructured optical fibre (MOF). Some new numerical results illustrating the versatility and accuracy of our approach are to be given.Design/methodology/approachA method involving both finite elements and perfectly matched layer (PML) is proposed.FindingsA rigorous definition of the leaky modes is proposed that leads to a proof of the validity of the PML approach together with a rule for the choice of the PML parameters.Originality/valueThe choice of parameters associated with the PML are discussed in great detail. The accuracy of the constant of propagation (and especially the imaginary part) are highlighted.
Adaptive time integration for electromagnetic models with sinusoidal excitation
Authors: Benderskaya Galina , De Gersem Herbert , Ackermann Wolfgang , Weiland Thomas 
Published: January 2008

PurposeTo provide a reliable numerical technique for the time integration of the electromagnetic models with sinusoidal excitation.Design/methodology/approachThe numerical integration of an electrotechnical problem is commonly carried out using adaptive time stepping. For one particular selected time step, Runge‐Kutta (RK) adaptive integration methods deliver two approximations to the solution with different order of approximation. The difference between both is used to estimate the local error.FindingsStandard error‐controlled RK time integration fails for electromagnetic problems with sinusoidal excitation when the adaptive time step selection relies upon the comparison of a main solution and an embedded solution where the difference of orders is one. This problem is overcome when the embedded solution differs by two orders of approximations. Such embedded solution is efficiently constructed by putting appropriate order conditions on the coefficients of the Butcher table.Originality/valueUsing the technique proposed in the paper, electromagnetic problems with sinusoidal dynamics can also be effectively tackled.
Computational methods for modeling of complex sources
Authors: Johansson Markus , Nord Lovisa E. , Kopecký Rudolf , Fhager Andreas , Persson Mikael 
Published: January 2008

PurposeThe purpose of this study is to develop and compare two methods of determining the total field, including phase information, when only field amplitudes have been measured on a set of planes in the near field of a complex electromagnetic source.Design/methodology/approachThe first method is a gradient‐based optimization algorithm, based on the adjoint fields. The second method employs an optimization algorithm based on the phase angle gradients of a functional.FindingsThe first method, the adjoint field method, is functioning well for a 2D test case. The second method, the phase angle gradient method, gives very good results for 3D test cases.Research limitations/implicationsThe next step is to test the methods with results from real measurement data.Practical implicationsThe developed methods are intended for use in dosimetry studies and other applications, where the field distribution from electromagnetic sources are needed.Originality/valueThe methods extend previously made constant phase approximations. The present methods are useful in situations where the electromagnetic source is hard to model.
Fundamental investigation of 3D optimal design of open type magnetic circuit producing uniform field
Authors: Takahashi Norio , Akiyama Koji , Kato Hirokazu , Kishi Kanji 
Published: January 2008

PurposeTo provide an approach to design the optimal open type magnetic circuit of permanent magnet producing uniform field.Design/methodology/approachThe Biot‐Savart's law and evolution strategy are used for the initial design of permanent magnet configuration. In order to improve the uniformity, the ON/OFF method, which is the topology optimization method, is used for determining the shape of magnetic material which is set around the permanent magnet.FindingsThe optimal topology of permanent magnet and shape of magnetic material around it, which can produce nearly uniform field of about 0.15T, is obtained. The obtained uniformity is 3,583 ppm. More work for improving the uniformity is necessary.Originality/valueA new approach for obtaining the optimal shape of open type magnetic circuit which may be used for magnetic resonance imaging is carried out.
Design of a double‐sided tubular permanent‐magnet linear synchronous generator for wave‐energy conversion
Authors: Joseph Danson M. , Cronje Willem A. 
Published: January 2008

PurposeThe purpose of this paper is to present a double‐sided tubular linear machine layout direct‐drive applications, with particular focus on wave‐energy conversion. The paper documents both the computational and mathematical analysis of this novel machine layout.Design/methodology/approachThe selection and finite‐element optimisation of the permanent‐magnet array is presented. The machine is then modelled using magnetic circuit theory. By simultaneously solving the system of equations, a demonstrative design is developed and simulated so as to validate the mathematical model and compare the performance of the new layout with a traditional layout.FindingsA surface‐mounted magnetic array, with unshaped‐poles, is most suitable for the proposed layout. The mathematical model exhibits a suitable level of accuracy for design and analysis purposes. The calculated resultant force differs from the FEA calculation by 1.85 per cent. A higher force‐density is exhibited by the proposed layout, when compared with flat layouts, with a reduction of 36.5 per cent in the spatial footprint and magnetic material of the machine.Research limitations/implicationsAlthough the research is focused on the application of wave‐energy conversion, the techniques are application‐independent. However, certain design decisions should be reviewed for other applications.Practical implicationsThe practical implementation of such a machine poses many mechanical obstacles. These have been solved in theory, and are being implemented at the time of writing.Originality/valueThe combination of a double‐sided and a tubular layout has not previously been researched. This research fills that void and provides designers with the technical background and a mathematical model for development of such devices.
Improved AC‐resistance of multiple foil windings by varying foil thickness of successive layers
Authors: Pentz D.C. , Hofsajer I.W. 
Published: January 2008

PurposeThis paper aims to introduce a technique for optimizing conductor dimensions for construction of helical planar inductor windings with reduced ac‐ and dc‐resistance. The loss reduction is evaluated on simulation and experimental level.Design/methodology/approachHelical planar windings are currently manufactured by forming each conductive and insulating layer individually. The conductive layers are only interconnected later to form the winding. This process allows greater freedom in selecting the optimum conductor dimensions on a per‐layer basis. Methods are proposed for sinusoidal and non‐sinusoidal current excitation waveforms and shaped windings are introduced for further loss reduction where conductors are in close proximity to air gaps in magnetic cores.FindingsTraditional optimization of the conductor thickness used for foil wound inductors renders one single value used for each of the respective layers in the winding. This is a result of the manufacturing process involved in making traditional “barrel” windings. This optimization technique has simply been applied in planar inductors for the lack of alternatives up to now. It will be shown that large loss reduction may be achieved by manipulating the conductor dimensions of each layer individually.Originality/valueA new approach to optimization problems verified experimentally offers more efficient inductors.
Influence of the magnetic model accuracy on the optimal design of a car alternator
Authors: Cros J. , Radaorozandry L. , Figueroa J. , Viarouge P. 
Published: January 2008

PurposeThe machine design with optimization method using analytical models is efficient to evaluate a large number of variables because these models are faster to solve. Nevertheless, the validation of the final optimal solution by FE simulation often shows that some specification constraints are not verified. To solve the problem, it is possible to apply a hybrid approach for the design method while combining analytical methods and 3D FE simulations to compensate analytical model errors. The paper addresses this.Design/methodology/approachEach intermediate optimal solution is evaluated by FE simulation to quantify the analytical model errors. Correction coefficients are derived from this evaluation and another optimization process is performed. With this method, the convergence of the hybrid optimal design process is obtained with a limited number of FE simulations.FindingsThis study shows that it is possible to compensate errors of analytical models with a limited number of 3D field calculations during a global optimization design process. The 3D FE software validates the optimal solution but this solution is also a function of the sensitivity of analytical models that is not improved by the correction method.Practical implicationsThis error compensation of analytical models using FE simulations can be applied for the design of a wide range of electromagnetic devices with optimization methods.Originality/valueThis paper presents a correction method that guaranteed the validity of the solution after the optimization process when analyzed with a FE software.
Modeling of a beam structure with piezoelectric materials: introduction to SSD techniques
Authors: Corcolle Romain , Salaün Erwan , Bouillault Frédéric , Bernard Yves , Richard Claude , Badel Adrien , Guyomar Daniel 
Published: January 2008

PurposeTo provide a model that allows testing and understanding special damping techniques.Design/methodology/approachThe finite element modeling takes into account the piezoelectric coupling. It is used with a non linear electrical circuit. The approach leads to an accurate tool to observe the behavior of the non linear damping techniques such as synchronized switch damping.FindingsThe model has been validated by comparison with Ansys® but the CPU time required for the model is around one hundred times shorter.Research limitations/implicationsThe proposed model is 1D and the assumptions to use it are not verified for all structures.Practical implicationsThe authors obtain a useful tool for the design of damping structures (for example to find the best localisation of the piezoelectric patches and to test electrical circuits).Originality/valueThe model is used for the design and conception of damping as well as for harvesting structures.
Analysis of the stray magnetic field created by faulty electrical machines
Authors: Bui V.P. , Chadebec O. , Rouve L‐L. , Coulomb J‐L. 
Published: January 2008

PurposeThis paper aims to compute the magnetic stray field created by faulty electrical machines.Design/methodology/approachThis paper proposes two approaches to compute the magnetic stray field created by faulty electrical machines. The first one presents a homogenized FEM method. The second one is based on a combination of an analytical expression for the magnetic field in the machine air gap with an integral method.FindingsThe studies show good agreement and demonstrate the reliability of the approach.Originality/valueTwo models developed in this paper originally used to compute the stray magnetic field of electrical machines. They can contribute to develop new tools for fault monitoring.
Analysis of the structure‐dynamic behaviour of an induction machine with balancing kerfs
Authors: Schlensok C. , Hameyer K. 
Published: January 2008

PurposeTo present results of research closely linked with real life applications. It resumes work of a period of about two years.Design/methodology/approachApplying the finite‐element method (FEM) the impact of balancing kerfs in the bars of squirrel‐cage rotors of a small scale, mass series induction machine (IM) is studied. For the analysis and design optimization of the IM both, 2D electromagnetic, multi‐slice and 3D structure‐dynamic models are considered. Introducing and applying a novel 2D‐3D force‐transformation scheme, all possible balancing variants of the IM are studied in terms of electromagnetic and mechanical behaviour.FindingsThe obtained results lead to a significant improvement of the studied IM. In fact, it is found, that the method of balancing the rotor by carving the rotor bars results in higher unbalanced pull rather than reducing it. This is due to electromagnetic unbalance caused by balancing. Hence, the IM is no longer balanced in series production. This again leads to a major economic benefit.Research limitations/implicationsUsing the FEM for simulation of structure dynamic problems is often limited to how the boundary layers are handled. In real life materials are not “connected” but glued or clamped. Therefore, the behaviour can only be adopted by manipulating the material parameters derived from iterative parameter adoption by measurement.Practical implicationsOwing to the findings the IM is no longer balanced in series production, leading to a significant reduction of costs. In general, the applied methods can be used for the analysis and optimization of any kind of manufacturing or tolerance problem of electrical machines such as various kinds of eccentricity, punching kerfs, broken bars, magnetization errors in permanent‐magnet machines, etc.Originality/valueThis contribution gives a close insight of how to study the impact of manufacturing and tolerance problems of electric machinery, applying the method to an IM with balancing kerfs.
Wound magnetic core consequences on false residual currents
Authors: Colin B. , Kedous‐Lebouc A. , Chillet C. , Mas P. 
Published: January 2008

PurposeGeometric or magnetic anomalies in the wound magnetic core of a residual current circuit breaker can be responsible of its abnormal tripping. The purpose of this paper is to analyse the core shape contribution to false residual currents (FRCs).Design/methodology/approachTo study precisely the core shape contribution, FEM simulations are investigated. First a 2D multilayer geometry is described thanks to linear regions. Then an apparent anisotropic bulk core is developed and validated in 2D and in 3D.FindingsThe air gaps between the magnetic layers develop a shielding effect responsible of the core high sensibility to primary conductors eccentricity. This effect can be easily represented using an anisotropic bulk core model.Research limitations/implicationsThe anisotropic material model is basic and has known limitations. Future research should see the development of a new model.Originality/valueFRCs can considerably disturb operation of residual current device. This paper provides new hypothesis on the origin of theses currents and proposes an anisotropic magnetic material model that simplifies FRC study.
Finite element formalism for micromagnetism
Authors: Szambolics H. , Buda‐Prejbeanu L.D. , Toussaint J.C. , Fruchart O. 
Published: January 2008

PurposeThe aim of this work is to present the details of the finite element approach that was developed for solving the Landau‐Lifschitz‐Gilbert (LLG) equations in order to be able to treat problems involving complex geometries.Design/methodology/approachThere are several possibilities to solve the complex LLG equations numerically. The method is based on a Galerkin‐type finite element approach. The authors start with the dynamic LLG equations, the associated boundary condition and the constraint on the magnetization norm. They derive the weak form required by the finite element method. This weak form is afterwards integrated on the domain of calculus.FindingsThe authors compared the results obtained with our finite element approach with the ones obtained by a finite difference method. The results being in very good agreement, it can be stated that the approach is well adapted for 2D micromagnetic systems.Research limitations/implicationsThe future work implies the generalization of the method to 3D systems. To optimize the approach spatial transformations for the treatment of the magnetostatic problem will be implemented.Originality/valueThe paper presents a special way of solving the LLG equations. The time integration a backward Euler method has been used, the time derivative being calculated as a function of the solutions at times n and n+1. The presence of the constraint on the magnetization norm induced a special two‐step procedure for the calculation of the magnetization at instant n+1.
A 3D electric vector potential formulation for dynamic hysteresis and losses
Authors: Maloberti O. , Mazauric V. , Meunier G. , Kedous‐Lebouc A. 
Published: January 2008

PurposeThe purpose of this paper is to introduce the dynamic hysteresis and losses of soft magnetic materials in numerical computation of high‐sensitive devices.Design/methodology/approachSo as to do this, the authors propose to lump all the microscopic dynamic effects due to averaging and smoothing techniques that lead to the definition of a dynamic field as proposed by other contributions. In this paper, the method to implement the modified field diffusion process in finite element computations is investigated, explained, detailed and put to the test.FindingsIn order to take microscopic magnetization reversal processes and eddy currents that damp the field at the mesoscopic scale, the authors have been led to define a new dynamic property Λ representative of the magnetic structure and its easiness to change. It is involved in an additional term in both the magnetic behaviour law and the bulk and surface coupling formulations describing the physical problem in iron and at the borders.Research limitations/implicationsThis model can only be used for macroscopic pieces for which each dimension is bigger than at least four times the characteristic length of magnetic domains.Originality/valueThe originality of the paper comes from the need to investigate the possibility to predict iron losses and the corresponding dynamic hysteresis during the processing computation of power electrical devices such as accurate sensors and high‐sensitive actuators of earth leakage circuit breaker for example.
New discretisation scheme based on splines for volume integral method
Authors: Reboud Christophe , Prémel Denis , Lesselier Dominique , Bisiaux Bernard 
Published: January 2008

PurposeA numerical model dedicated to external eddy current inspection of tubes has been developed using the volume integral method (VIM). The purpose of this paper is to suggest new discretization schemes based on non‐uniform B‐splines for the solution of the state equation with the method of moments (MoM).Design/methodology/approachVIM is a semi‐analytical approach providing fast and accurate results for the simulation of eddy current testing (ECT) of pieces with canonical geometries. The state equation derived with this formalism is solved using the Galerkin variant of the well‐known MoM.FindingsThis paper shows that an accuracy improvement is achieved in MoM by using B‐splines with degree 1 or 2 as projection functions in MoM instead of pulse functions. Moreover, comparisons between simulation results show that, for all ECT configurations tested, the use of degree 1 B‐splines is sufficient to get this improvement.Originality/valueThe use of B‐splines functions has already been proposed for MoM in the literature, but not in the framework of the Galerkin variant of MoM. This paper also shows quantitative comparisons between experiment and simulation as well as a study of the minimal degree required to get an accuracy improvement in MoM.