Finite element models for studying the capacitive behaviour of wound components

peer reviewedFinite 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

A Perturbation Finite Element Technique for Modeling Electrostatic MEMS

Projet ARC (Convention 03/08-298, “Modélisation, Simulation Multiphysique et Optimisation de Problèmes Couplés - Application aux Micro-Systèmes Électromécaniques (MEMS)”

Subproblem h-Conform Formulation for Accurate Thin Shell Models Between Conducting and Nonconducting Regions

peer reviewedA subproblem method (SPM) with h-formulation is developed for correcting the inaccuracies near edges and corners that arise from using thin shell (TS) models to replace thin volume regions by surfaces. The developed surface-to-volume correction problem is defined as a step of multiple SPs, with inductors and magnetic or conducting regions, some of them being thin. The TS model assumes that the fields in the thin regions are approximated by a priori 1-D analytical distributions along the shell thickness (C. Geuzaine et al., “Dual formulations for the modeling of thin electromagnetic shells using edge elements,” IEEE Trans. Magn., vol. 36, no. 4, pp. 799–802, 2000). Their interior is not meshed and ratherextracted from the studied domain, which is reduced to a zero-thickness double layer with interface conditions (ICs) linked to 1-D analytical distributions that however neglect end and curvature effects. This leads to inaccuracies near edges and corners that increase with the thickness. To cope with these difficulties, the authors have recently proposed a SPM based on the h-formulation for a thin region located between non-conducting regions (Vuong Q. Dang et al., “Subproblem Approach for Thin Shell Dual Finite Element Formulations”, IEEE Trans. Magn., vol. 48, no. 2, pp. 407–410, 2012). The magnetic field h is herein defined in nonconducting regions by means of a magnetic scalar potential , i.e. h = -grad{\phi} , with discontinuities of through the TS. In this paper, the SPM is extended to account for thin regions located between conducting regions or between conducting and nonconducting regions, in the general case of multiply connected regions. In these regions, the potential is not defined anymore on both sides of the TS and the problem has to be expressed in terms of the discontinuities of h, possibly involving on one side only, to be strongly defined via an IC through the TS. In the proposed SP strategy, a reduced problem with only inductors is first solved on a simplified mesh without thin and volume regions. Its solution gives surface sources (SSs) as ICs for added TS regions, and volume sources (VSs) for possible added volume regions. The TS solution is further improved by a volume correction via SSs and VSs that overcome the TS assumptions, respectively suppressing the TS model and adding the volume model. Each SP has its own separate mesh, which increases the computational efficiency. Details on the proposed method will be given in the extended paper, with practical applications

The fast multipole method for electromagnetic field computation in numerical and physical hybrid systems

nrpages: 187status: publishe

A perturbation method for the 3D Finite Element Modeling

Projet ARC (Convention 03/08-298, “Modélisation, Simulation Multiphysique et Optimisation de Problèmes Couplés - Application aux Micro-Systèmes Électromécaniques (MEMS)”

Time-domain finite-element homogenisation of laminated iron cores with net circulating currents

peer reviewedThis 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

Homogenisation of Windings and Laminations in Time-Domain Finite-Element Modeling of Electrical Machines

peer reviewedThis 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