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See detailComparison of Nonlinear Domain Decomposition Schemes for Coupled Electromechanical Problems
Halbach, Alexandre ULg; Dular, Patrick ULg; Geuzaine, Christophe ULg

in IEEE Transactions on Magnetics (2016), 52(3),

The aim of this paper is to compare several domain decomposition schemes for nonlinear, coupled electromechanical problems. Both staggered and monolithic electrostatic/elastic formulations are considered ... [more ▼]

The aim of this paper is to compare several domain decomposition schemes for nonlinear, coupled electromechanical problems. Both staggered and monolithic electrostatic/elastic formulations are considered for the multiphysics problem. The domain decomposition is applied either to a single multiphysics iteration, which corresponds to a linear problem, or to the full nonlinear multiphysics resolution. In the latter, the problem solved at each domain decomposition iteration is nonlinear. The influence of the elastic wave’s frequency and the electrostatic potential on the convergence rate and the computational cost of the algorithm is investigated on a 2-D model of a vibrating micromembrane array. [less ▲]

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See detailFinite-Element Homogenization of Laminated Iron Cores With Inclusion of Net Circulating Currents Due to Imperfect Insulation
Gyselinck, Johan; Dular, Patrick ULg; Krähenbühl, Laurent et al

in IEEE Transactions on Magnetics (2016), 52(3),

This paper deals with the time-domain homogenization of laminated cores in 2-D or 3-D finite-element (FE) models of electromagnetic devices, allowing for net circulating current in the laminations (e.g ... [more ▼]

This paper deals with the time-domain homogenization of laminated cores in 2-D or 3-D finite-element (FE) models of electromagnetic devices, allowing for net circulating current in the laminations (e.g., due to imperfect or damaged insulation). The homogenization is based on the expansion of the induction throughout the lamination thickness using a set of orthogonal polynomial basis functions (BFs), in conjunction with the magnetic vector potential formulation. These BFs allow for net flux, net current, and skin effect in the laminations; by choosing the number of BFs, one can compromise between accuracy and computational cost. The approach is validated through a linear 2-D test case with in-plane imposed and induced current density. A brute-force model, in which all laminations are finely meshed, produces the reference solution. The extension to nonlinear 3-D problems is expected to be straightforward. [less ▲]

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See detailInclusion of a Direct and Inverse Energy-Consistent Hysteresis Model in Dual Magnetostatic Finite-Element Formulations
Jacques, Kevin ULg; Sabariego, Ruth Vazquez; Geuzaine, Christophe ULg et al

in IEEE Transactions on Magnetics (2016), 52(3), 1-4

This paper deals with the implementation of an energy-consistent ferromagnetic hysteresis model in 2-D finite-element computations. This vector hysteresis model relies on a strong thermodynamic foundation ... [more ▼]

This paper deals with the implementation of an energy-consistent ferromagnetic hysteresis model in 2-D finite-element computations. This vector hysteresis model relies on a strong thermodynamic foundation and ensures the closure of minor hysteresis loops. The model accuracy can be increased by controlling the number of intrinsic cell components, while parameters can be easily fitted on common material measurements. Here, the native h-based material model is inverted using the Newton-Raphson method for its inclusion in the magnetic vector potential formulation. Simulations are performed on a 2-D T-shaped magnetic circuit exhibiting rotational flux. By way of validation, the results are compared with those obtained with the dual magnetic scalar potential formulation. A very good agreement for global quantities is observed. [less ▲]

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See detailReduced Order Model for Accounting for High Frequency Effects in Power Electronic Components
Paquay, Yannick ULg; Geuzaine, Christophe ULg; Hasan, Md. Rokibul et al

in IEEE Transactions on Magnetics (2016)

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See detailDesign Sensitivity Analysis for Shape Optimization of Nonlinear Magnetostatic Systems
Kuci, Erin ULg; Henrotte, François; Duysinx, Pierre ULg et al

in IEEE Transactions on Magnetics (2016), 52(3),

The paper discusses the sensitivity analysis for the shape optimization of a nonlinear magnetostatic system, evaluated both by direct and adjoint approaches. The calculations rely on the Lie derivative ... [more ▼]

The paper discusses the sensitivity analysis for the shape optimization of a nonlinear magnetostatic system, evaluated both by direct and adjoint approaches. The calculations rely on the Lie derivative concept of differential geometry where the flow is the velocity field associated with the modification of a geometrical parameter in the model. The resulting sensitivity formulas can be expressed naturally in a finite element setting through a volume integral in the layer of elements connected to the surface undergoing shape modification. The accuracy of the methodology is analyzed on a 2D model of an interior permanent magnet motor (IPM), and on a 3D model of a permanent magnet system. [less ▲]

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See detailNonlinear Interpolation on Manifold of Reduced Order Models in Magnetodynamic Problems
Paquay, Yannick ULg; Bruls, Olivier ULg; Geuzaine, Christophe ULg

in IEEE Transactions on Magnetics (2016), 52(3), 1-4

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See detailProgressive Current Source Models in Magnetic Vector Potential Finite-Element Formulations
Dular, Patrick ULg; Kuo-Peng, Patrick; Ferreira da Luz, Mauricio V. et al

in IEEE Transactions on Magnetics (2016), 52(3),

Progressive refinements of the current sources in magnetic vector potential finite-element (FE) formulations are done with a subproblem method. The sources are first considered through magnetomotive force ... [more ▼]

Progressive refinements of the current sources in magnetic vector potential finite-element (FE) formulations are done with a subproblem method. The sources are first considered through magnetomotive force or Biot–Savart models up to their volume FE models, from statics to dynamics. A novel way to define the source fields is proposed to lighten the computational efforts, through the conversion of the common volume sources to surface sources, without the need for any preresolution. Accuracy improvements can then be obtained for local currents and fields, and global quantities, i.e., inductances, resistances, Joule losses, and forces. [less ▲]

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See detailComputation of Source for Non-Meshed Coils in a Reduced Domain with A–V Formulation
Ferrouillat, Pauline; Guérin, Christophe; Meunier, Gérard et al

in IEEE Transactions on Magnetics (2016), 52(3),

The discretized source magnetic vector potential Aj, projected from source field Hs with H(curl,Ω) semi-norm, is studied for non-meshed coils with magnetic vector potential A and electric scalar potential ... [more ▼]

The discretized source magnetic vector potential Aj, projected from source field Hs with H(curl,Ω) semi-norm, is studied for non-meshed coils with magnetic vector potential A and electric scalar potential V formulation. As a novelty, source potential Aj is computed in a reduced domain Ωred instead of the complete domain Ω. For domains with fixed and moving parts, potential Aj can be computed on each part, for each of the related current sources, with no need to ensure its continuity between these parts. [less ▲]

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See detailDomain Decomposition Methods for Time-Harmonic Electromagnetic Waves with High Order Whitney Forms
Marsic, Nicolas ULg; Waltz, Caleb; Lee, Jin-Fa et al

in IEEE Transactions on Magnetics (2016), 52(3),

Classically, domain decomposition methods (DDM) for time-harmonic electromagnetic wave propagation problems make use of the standard, low order, Nédélec basis functions. This paper analyzes the ... [more ▼]

Classically, domain decomposition methods (DDM) for time-harmonic electromagnetic wave propagation problems make use of the standard, low order, Nédélec basis functions. This paper analyzes the convergence rate of DDM when higher order finite elements are used for both volume and interface discretizations, in particular when different orders are used in the volume and on the interfaces. [less ▲]

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See detailGetDDM: an Open Framework for Testing Optimized Schwarz Methods for Time-Harmonic Wave Problems
Thierry, Bertrand; Vion, Alexandre; Tournier, Simon et al

in Computer Physics Communications (2016), 203

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See detailGeometrical validity of curvilinear pyramidal finite elements
Johnen, Amaury ULg; Geuzaine, Christophe ULg

in Journal of Computational Physics (2015), 299

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See detailSequential decision-making approach for quadrangular mesh generation
Johnen, Amaury ULg; Ernst, Damien ULg; Geuzaine, Christophe ULg

in Engineering with Computers (2015), 31(4), 729-735

A new indirect quadrangular mesh generation algorithm which relies on sequential decision-making techniques to search for optimal triangle recombinations is presented. In contrast to the state-of-art ... [more ▼]

A new indirect quadrangular mesh generation algorithm which relies on sequential decision-making techniques to search for optimal triangle recombinations is presented. In contrast to the state-of-art Blossom-quad algorithm, this new algorithm is a good candidate for addressing the 3D problem of recombining tetrahedra into hexahedra. [less ▲]

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See detailCorrection of homogenized lamination stacks via a subproblem finite element method
Dular, Patrick ULg; Ferreira da Luz, Mauricio; Kuo-Peng, Patrick et al

in COMPEL (2015), 34(5), 1553-1563

Purpose – The purpose of this paper is to develop a subproblem finite element method for progressive modeling of lamination stacks in magnetic cores, from homogenized solutions up to accurate eddy current ... [more ▼]

Purpose – The purpose of this paper is to develop a subproblem finite element method for progressive modeling of lamination stacks in magnetic cores, from homogenized solutions up to accurate eddy current distributions and losses. Design/methodology/approach – The homogenization of lamination stacks, subject to both longitudinal and transversal magnetic fluxes, is first performed and is followed by local correction subproblems in certain laminations separately, surrounded by their insulating layers and the remaining laminations kept homogenized. The sources for the local corrections are originally defined via interface conditions to allow the coupling between homogenized and non-homogenized portions. Findings – The errors proper to the homogenization model, which neglects fringing effects, can be locally corrected in some selected portions via local eddy current subproblems considering the actual geometries and properties of the related laminations. The fineness of the mesh can thus be concentrated in these portions, while keeping a coupling with the rest of the laminations kept homogenized. Research limitations/implications – The method has been tested on a 2D case having linear material properties. It is however directly applicable in 3D. Its extension to the time domain with non-linear properties will be done. Originality/value – The resulting subproblem method allows accurate and efficient calculations of eddy current losses in lamination stacks, which is generally unfeasible for real applications with a single problem approach. The accuracy and efficiency are obtained thanks to a proper refined mesh for each subproblem and the reuse of previous solutions to be locally corrected only acting in interface conditions. Corrections are progressively obtained up to accurate eddy current distributions in the laminations, allowing to improve the resulting global quantities: the Joule losses in the laminations, and the resistances and inductances of the surrounding windings. [less ▲]

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See detailModel refinements of transformers via a subproblem finite element method
Dular, Patrick ULg; Kuo-Peng, Patrick; Ferreira da Luz, Mauricio et al

in Proceedings of ISEF 2015 (2015, September)

A progressive modeling of transformers is performed via a subproblem finite element method. A complete problem is split into subproblems with different adapted overlapping meshes. Model refinements are ... [more ▼]

A progressive modeling of transformers is performed via a subproblem finite element method. A complete problem is split into subproblems with different adapted overlapping meshes. Model refinements are performed from ideal to real flux tubes, 1-D to 2-D to 3-D models, linear to nonlinear materials, perfect to real materials, single wire to volume conductor windings, and homogenized to fine models of cores and coils, with any coupling of these changes. The proposed unified procedure efficiently feeds each subproblem via interface conditions, which lightens mesh-to-mesh sources transfers, and quantifies the gain given by each refinement on both local fields and global quantities. [less ▲]

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See detailUsing a vector Jiles-Atherton hysteresis model for isotropic magnetic materials with the FEM, Newton-Raphson method and relaxation procedure
Guérin, Christophe; Jacques, Kevin; Sabariego, Ruth V. et al

in Proceedings of NUMELEC 2015 (2015, June)

This paper deals with the use of a vector Jiles- Atherton hysteresis model included in 2D finite element modelling. The Newton-Raphson algorithm is used with a relaxtion procedure, which ensures the ... [more ▼]

This paper deals with the use of a vector Jiles- Atherton hysteresis model included in 2D finite element modelling. The Newton-Raphson algorithm is used with a relaxtion procedure, which ensures the convergence in most of the cases. We have simulated a T-shaped magnetic circuit with rotating fields and then a three-phase transformer model. [less ▲]

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See detailFinite element models for studying the capacitive behaviour of wound components
De Grève, Zacharie; Dular, Patrick ULg; Sabariego, Ruth V. et al

in Proceedings of COMPUMAG 2015 (2015, June)

Finite element models of increasing accuracy are proposed for the study of the capacitive behaviour of wound magnetic components. Simple models, which are based on the classical assumption of a decoupling ... [more ▼]

Finite element models of increasing accuracy are proposed for the study of the capacitive behaviour of wound magnetic components. Simple models, which are based on the classical assumption of a decoupling between electric and magnetic fields, are first described. Formulations which enable such a coupling are then presented. The models are tested on various coreless inductors, made of round conductors or copper sheets. The results are discussed and compared with experimental data measured with an impedance analyzer. [less ▲]

Detailed reference viewed: 48 (2 ULg)