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Time-domain finite-element homogenisation of laminated iron cores with net circulating currents ; Dular, Patrick ; et al in Proceedings of COMPUMAG 2015 (2015, June) This paper deals with the time-domain homogenization of laminated cores in 2D or 3D finite element (FE) models of electromagnetic devices, in particular allowing for net circulating current in the ... [more ▼] This paper deals with the time-domain homogenization of laminated cores in 2D or 3D finite element (FE) models of electromagnetic devices, in particular allowing for net circulating current in the laminations (which may result from imperfect or damaged insulation). The homogenization is based on the decomposition of the variation of the induction in the lamination thickness by means of a orthogonal set of polynomial basis functions, in conjunction with the magnetic vector potential (MVP) formulation. The conventional even skin-effect basis functions are linked to net flux, whereas the odd ones are now added so as to allow for net current. The approach is validated through a simple linear 2D test case, although the extension to 3D nonlinear problems is straightforward. [less ▲] Detailed reference viewed: 15 (0 ULg)Using a vector Jiles-Atherton hysteresis model for isotropic magnetic materials with the FEM, Newton-Raphson method and relaxation procedure ; ; 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 ▲] Detailed reference viewed: 33 (2 ULg)Homogenisation of Windings and Laminations in Time-Domain Finite-Element Modeling of Electrical Machines ; Geuzaine, Christophe ; Vazquez Sabariego, Ruth in Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November) This paper deals with time-domain homogenisation of multi-turn windings and laminated cores in 2D and 3D finite- element (FE) modelling of rotating electrical machines. Herein the number of additional ... [more ▼] This paper deals with time-domain homogenisation of multi-turn windings and laminated cores in 2D and 3D finite- element (FE) modelling of rotating electrical machines. Herein the number of additional degrees of freedom (auxiliary field variables) in the homogenised regions can be fixed depending on the extent of the eddy current effects and on the desired accuracy. The homogenisation technique is illustrated and validated by means of a 2D model of a switched reluctance motor. Global quantities, such as the phase impedance, converge very well to those produced by a precise but very expensive 3D model. [less ▲] Detailed reference viewed: 176 (6 ULg)Time-domain finite-element modelling of laminated iron cores – Large skin effect homogenization considering the Jiles-Atherton hysteresis model Vazquez Sabariego, Ruth ; Niyonzima, Innocent ; Geuzaine, Christophe et al in Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November) This paper deals with the incorporation of the Jiles- Atherton (J-A) hysteresis model in a time-domain finite-element homogenization technique for laminated iron cores. The separate discretization of each ... [more ▼] This paper deals with the incorporation of the Jiles- Atherton (J-A) hysteresis model in a time-domain finite-element homogenization technique for laminated iron cores. The separate discretization of each lamination is avoided by using dedicated skin-effect basis functions, which also serve to interpolate the J- A hysteretic material law. As validation test case, a stacked ring core surrounded by a toroidal coil is considered. [less ▲] Detailed reference viewed: 98 (11 ULg)Time-domain surface impedance boundary conditions enhanced by coarse volume finite-element discretisation Vazquez Sabariego, Ruth ; Geuzaine, Christophe ; Dular, Patrick et al in IEEE Transactions on Magnetics (2012), 48(2), 631-634 In computational magnetodynamics, surface impedance boundary conditions allow to accurately account for high-frequency flux components while removing the massive conducting regions from the computation ... [more ▼] In computational magnetodynamics, surface impedance boundary conditions allow to accurately account for high-frequency flux components while removing the massive conducting regions from the computation domain. The time-domain approach previously proposed by the authors relies on the spatial discretisation of a 1-D eddy-current problem by means of dedicated basis functions derived from the analytical frequency-domain solution. In this paper, these time-domain impedance conditions are combined with a coarse volume finite-element discretisation of the massive conductors to capture slowly varying flux components. The accuracy of the hybrid approach can further be improved by introducing a fictitious frequency-dependent conductivity. The method is illustrated and validated by means of 1-D and 2-D test cases in the frequency and time domain. [less ▲] Detailed reference viewed: 47 (8 ULg)Time-Domain Surface Impedance Boundary Conditions Enhanced by Coarse Volume Finite-Element Discretisation V Sabariego, Ruth ; Geuzaine, Christophe ; Dular, Patrick et al (2011) The time-domain surface impedance boundary conditions allow to accurately account for the high-frequency flux components while removing the massive conducting regions from the computation domain. In this ... [more ▼] The time-domain surface impedance boundary conditions allow to accurately account for the high-frequency flux components while removing the massive conducting regions from the computation domain. In this paper, a coarse volume finite-element discretization of the conductors together with a fictitious frequency-dependent conductivity are added to capture the slow varying flux components. This hybrid approach extends thus the frequency range of these impedance conditions. A 2-D test case illustrates the method. [less ▲] Detailed reference viewed: 26 (1 ULg)Considering Laminated Cores and Eddy Currents in 2D and 3D Finite Element Simulation of Electrical Machines ; Geuzaine, Christophe ; V Sabariego, Ruth (2011) This paper deals with a time-domain homogeniza- tion method for laminated cores and its application to the 2D finite element simulation of rotating electrical machines. The number of additional degrees of ... [more ▼] This paper deals with a time-domain homogeniza- tion method for laminated cores and its application to the 2D finite element simulation of rotating electrical machines. The number of additional degrees of freedom of the model, for considering the variation of the flux density along the lamination thickness, can be tuned so as to reach a good compromise between accuracy and computation time. The results obtained for a switched reluctance motor agree very well with those produced by a precise full 3D model in which eddy currents are explicitly modeled. [less ▲] Detailed reference viewed: 159 (3 ULg)Homogenization of form- wound windings in finite element modelling of electrical machines ; Dular, Patrick ; et al in IEEE Transactions on Magnetics (2010), 46(8), 2852-2855 In this paper, the authors deal with the finite-element (FE) modeling of eddy-current effects in form-wound windings of electrical machines using a previously proposed general frequency- and time-domain ... [more ▼] In this paper, the authors deal with the finite-element (FE) modeling of eddy-current effects in form-wound windings of electrical machines using a previously proposed general frequency- and time-domain homogenization method. By way of demonstration and validation, a real-life 1250-kW induction machine with double-layer stator winding is considered. The skin and proximity effects in one stator conductor (copper bar) are first quantified by means of a simple low-cost FE model, leading to complex and frequency-dependent coefficients for the homogenized winding (reluctivity for proximity effect and conductivity or resistance for skin effect). These complex coefficients are subsequently translated into real-valued and constant coefficients that allow for time-domain homogenization when introducing a limited number of additional degrees of freedom in the FE model. All results obtained with the homogenized model (considering one conductor or a complete slot) agree well with those produced by a brute-force approach (modeling and finely discretizing each conductor). [less ▲] Detailed reference viewed: 32 (1 ULg)Surface-Impedance Boundary Conditions in Dual Time-Domain Finite-Element Formulations V Sabariego, Ruth ; Dular, Patrick ; Geuzaine, Christophe et al in IEEE Transactions on Magnetics (2010), 46(8), 3524-3531 This paper deals with time-domain surface-impedance boundary conditions in computational magnetodynamics considering two dual finite-element formulations and a nonlinear magnetic constitutive law. Based ... [more ▼] This paper deals with time-domain surface-impedance boundary conditions in computational magnetodynamics considering two dual finite-element formulations and a nonlinear magnetic constitutive law. Based on the resolution of the 1-D eddy-current problem in a semi-infinite slab, the massive conducting region is accounted for by choosing a number of exponentially decreasing trigonometric basis functions covering the relevant frequency range of the application in hand. Herein the method is elaborated for the magnetic-vector- potential formulation and the magnetic-field formulation. Results for both formulations are compared and validated on 2-D linear and nonlinear test cases. [less ▲] Detailed reference viewed: 96 (14 ULg)Non-linear magnetic model refinement via a finite element subproblem method Dular, Patrick ; V Sabariego, Ruth ; et al in Proceedings of the XXI Symposium on Electromagnetic Phenomena in Nonlinear Circuits (EPNC 2010) (2010, June) Model refinements of non-linear magnetic circuits are performed via a finite element subproblem method. A complete problem is split into subproblems to allow a progression from 1- D to 3-D including ... [more ▼] Model refinements of non-linear magnetic circuits are performed via a finite element subproblem method. A complete problem is split into subproblems to allow a progression from 1- D to 3-D including linear to non-linear model corrections. Its solution is then expressed as the sum of the subproblem solutions supported by different meshes. A convenient and robust correction procedure is proposed allowing independent overlapping meshes for both source and reaction fields. The procedure simplifies both meshing and solving processes, and quantifies the gain given by each model refinement on both local fields and global quantities. [less ▲] Detailed reference viewed: 17 (1 ULg)Combining Surface Impedance Boundary Conditions with Volume Discretisation in Time-Domain Finite-Element Modeling ; Dular, Patrick ; Geuzaine, Christophe et al in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010, May) In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as ... [more ▼] In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as previously proposed by the authors, are adopted so as to allow for high-frequency flux components (in a certain frequency band) without the need for very fine discretisation of the conducting region near its surface. These surface conditions are combined with a coarse FE mesh inside the region for conveying slowly varying flux components. The correct impedance behaviour can thus be obtained in a wide frequency range, from DC flux on. The approach is briefly demonstrated by means of a simple 1D test case. [less ▲] Detailed reference viewed: 35 (5 ULg)Finite-Element Analysis of a Shielded Pulsed-Current Induction Heater -- Experimental Validation of a Time-Domain Thin-Shell Approach V Sabariego, Ruth ; ; et al in COMPEL (2010), 29(6), 1585-1595 Purpose – The aim of this paper is the experimental validation of an original time-domain thin-shell formulation. The numerical results of a three-dimensional thin-shell model are compared with the ... [more ▼] Purpose – The aim of this paper is the experimental validation of an original time-domain thin-shell formulation. The numerical results of a three-dimensional thin-shell model are compared with the measurements performed on a heating device at different working frequencies. Design/methodology/approach – A time-domain extension of the classical frequency-domain thin-shell approach is used for the finite-element analysis of a shielded pulse-current induction heater. The time-domain interface conditions at the shell surface are expressed in terms of the average flux density vector in the shell, as well as in terms of a limited number of higher-order components. Findings – A very good agreement between measurements and simulations is observed. A clear advantage of the proposed thin-shell approach is that the mesh of the computation domain does not depend on the working frequency anymore. It provides a good compromise between computational cost and accuracy. Indeed, adding a sufficient number of induction components, a very high accuracy can be achieved. Originality/value – The method is based on the coupling of a time-domain 1D thin-shell model with a magnetic vector potential formulation via the surface integral term. A limited number of additional unknowns for the magnetic flux density are incorporated on the shell boundary. [less ▲] Detailed reference viewed: 43 (2 ULg)Surface-Impedance Boundary Conditions in Dual Time-Domain Finite-Element Formulations V Sabariego, Ruth ; Dular, Patrick ; Geuzaine, Christophe et al in Proceedings of the 17th Conference on the Computation of Electromagnetic Fields, COMPUMAG 2009 (2009, November) This paper deals with time-domain surface-impedance boundary conditions in computational magnetodynamics considering both magnetic-vector potential and magnetic-field formulation. Based on the resolution ... [more ▼] This paper deals with time-domain surface-impedance boundary conditions in computational magnetodynamics considering both magnetic-vector potential and magnetic-field formulation. Based on the resolution of the 1-D eddy-current problem in a semi-infinite slab, the massive conducting region is accounted for by choosing a number of exponentially decreasing trigonometric basis functions covering the relevant frequency range. Herein the method is elaborated for the magnetic-field formulation. Results for both formulations are compared and validated on a two-dimensional test case. [less ▲] Detailed reference viewed: 9 (3 ULg)Nonlinear time-domain finite-element modeling of thin electromagnetic shells V Sabariego, Ruth ; Geuzaine, Christophe ; Dular, Patrick et al in IEEE Transactions on Magnetics (2009), 45(3), 976-979 A nonlinear time-domain extension of the classical linear frequency-domain thin-shell approach is presented. The interface conditions are expressed in terms of the average magnetic flux density throughout ... [more ▼] A nonlinear time-domain extension of the classical linear frequency-domain thin-shell approach is presented. The interface conditions are expressed in terms of the average magnetic flux density throughout the shell thickness and a number of higher order components. The method is elaborated in the frame of the magnetic vector potential formulation. The nonlinear system of algebraic equations is solved by means of the Newton–Raphson scheme. To validate the new formulation, we consider a magnetic plate placed above a double line carrying a sinusoidal current. Results are compared with those obtained with a fine finite-element model. [less ▲] Detailed reference viewed: 56 (8 ULg)Surface-impedance boundary conditions in time-domain finite-element calculations ; Geuzaine, Christophe ; Dular, Patrick et al in IEEE Transactions on Magnetics (2009), 45(3), 1280-1283 The authors propose a novel time-domain extension of the well-known frequency-domain surface-impedance method in computational magnetodynamics. Herein, the 1-D eddy-current problem in a massive conducting ... [more ▼] The authors propose a novel time-domain extension of the well-known frequency-domain surface-impedance method in computational magnetodynamics. Herein, the 1-D eddy-current problem in a massive conducting region (semi-infinite slab) is considered via a number of exponentially decreasing trigonometric basis functions that cover the relevant skin-depth (or frequency) range of the application at hand. The method is elaborated for the 3-D magnetic-vector-potential formulation and is applied to a simple 2-D test case. Results are shown to converge well to those obtained with an accurate brute-force finite-element (FE) model. [less ▲] Detailed reference viewed: 80 (6 ULg)Direct Inclusion of Proximity-Effect Losses in Two-Dimensional Time-Domain Finite-Element Simulation of Electrical Machines ; Dular, Patrick ; Geuzaine, Christophe et al in Proceedings of the 8th International Symposium on Electric and Magnetic Fields (EMF2009) (2009) This paper deals with eddy-current effects in the distributed winding of electrical machines, and in particular with the proximity effect and the associated losses. A previously proposed homogenization ... [more ▼] This paper deals with eddy-current effects in the distributed winding of electrical machines, and in particular with the proximity effect and the associated losses. A previously proposed homogenization method for windings in two-dimensional (2D) time-domain finite-element (FE) models is shown to be applicable without additional computational cost, producing a precise estimate of the instantaneous proximity-effect losses. The method is illustrated by considering the conductors in a single stator slot of a 3kW induction motor. The brute-force model, with fine discretisation of each conductor, and the homogenized model yield macroscopic results that are very close to each other. [less ▲] Detailed reference viewed: 82 (10 ULg)h- and a-Formulations for the Time-Domain Modelling of Thin Electromagnetic Shells V Sabariego, Ruth ; Geuzaine, Christophe ; Dular, Patrick et al in IET Science, Measurement & Technology (2008), 2(6), 402-408 Thin conductive magnetic shells are accounted for by means of two different time-domain magnetodynamic finite-element formulations, namely the magnetic field formulation and the magnetic vector potential ... [more ▼] Thin conductive magnetic shells are accounted for by means of two different time-domain magnetodynamic finite-element formulations, namely the magnetic field formulation and the magnetic vector potential formulation. Both approaches are an extension of the classical linear frequency-domain thin-shell approximation. The interface conditions for the magnetic field formulation and the vector potential formulation are expressed in terms of the average current density and the average flux density, respectively, together with a number of higher-order components of these quantities. The proposed time-domain thin-shell approaches are validated by means of a 3D magnetodynamic problem. The results are shown to agree well with those obtained with a fine model, whereas the computation time is significantly reduced. [less ▲] Detailed reference viewed: 30 (1 ULg)Time-Domain Finite-Element Modeling of Thin Electromagnetic Shells ; V Sabariego, Ruth ; Dular, Patrick et al in IEEE Transactions on Magnetics (2008), 44(6), 742-745 In this paper, the authors propose a novel time-domain extension of the well-known frequency-domain thin-shell approach. The time-domain interface conditions at the shell surface are expressed in terms of ... [more ▼] In this paper, the authors propose a novel time-domain extension of the well-known frequency-domain thin-shell approach. The time-domain interface conditions at the shell surface are expressed in terms of the average (zero-order) instantaneous flux and current density vectors in the shell, as well as in terms of a limited number of higher-order components. The method is elaborated for a magnetic vector potential finite-element formulation. The validation is done by means of two 2-D test cases with pulsed magnetic field excitation. The results are in excellent agreement with those produced by a brute-force model in which the shell is meshed finely throughout its thickness. [less ▲] Detailed reference viewed: 129 (14 ULg)Time-Domain Homogenization of Windings in 3-D Finite Element Models V Sabariego, Ruth ; Dular, Patrick ; in IEEE Transactions on Magnetics (2008), 44(6), 1302-1305 This paper deals with the time-domain homogenization of multiturn windings in 3-D finite element (FE) models. An elementary two-dimensional (2-D) FE model allows for the global eddy-current ... [more ▼] This paper deals with the time-domain homogenization of multiturn windings in 3-D finite element (FE) models. An elementary two-dimensional (2-D) FE model allows for the global eddy-current characterization of the winding by means of dimensionless frequency and time-domain coefficients regarding skin and proximity effects. These coefficients are used in the FE model of the complete device. The 3-D homogenization method is validated by considering an axisymmetric 120-turn inductor for which a brute-force 2-D FE model (each turn is finely discretized) provides an accurate reference solution. [less ▲] Detailed reference viewed: 41 (10 ULg)Nonlinear time-domain finite-element modeling of thin electromagnetic shells V Sabariego, Ruth ; Geuzaine, Christophe ; Dular, Patrick et al in Proceedings of the 13th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2008) (2008, May) Detailed reference viewed: 8 (0 ULg) |
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