Fiche individuelle

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 employed to reduce the size of the stator core, the magnetic flux flows through several successive directions within the plane of the steel. So, the anisotropic behavior of the GO steel has to be considered in the design step of the related devices in order to improve their energy efficiency as well as their diagnosis based on modeling. In this paper, an anisotropic phenomenological iron loss model, quite recently developed, has been studied and successfully implemented in a finite element method (FEM) simulation environment. The implementation has been validated against experimental data achieved on an industrial conventional GO grade typically used in turbogenerators. The results show a good agreement of the computational results with the experiments for both quasi-static and dynamic regimes.

The purpose of this study is to investigate, through finite element (FE) simulations, the effect of the demagnetizing field in Epstein characterization of grain-oriented electrical steels. A 3D finite element simulation has been realized to represent the parallel and X-stacking configurations in the Epstein frame. The numerical results have been compared with experimental measures. In a parallel configuration, the measured induction is actually the one in the material, whereas the resulting magnetic field differs from the applied one (in magnitude and angle) due to the shape anisotropy (demagnetizing field). In X-stacking configuration, the resulting magnetic field is close to the applied magnetic field (and then the supposed excitation field in the Epstein frame), whereas the magnetic induction has deviated from the axis of the strips.

An improved starting point Newton method applied to 3-D scalar formulation in magnetostatics is proposed in this paper. Compared with the classical Newton method, the inexact-Newton and quasi-Newton methods are reported by testing on a benchmark problem as well as an industrial example. Remarkable convergence acceleration using the proposed strategy is observed, and thus, it significantly reduces the computational time.

The stray load losses (SLLs) in electrical machines represent a non-negligible 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 induction motor. The study is performed at locked rotor, no-load, and rated load conditions using a 3-D finite-element modeling approach. The influence of the leakage flux on the end-region conductive parts of the motor is analyzed together with the eddy current loss calculation. Finally, the SLLs are calculated and compared with the experimental measurements based on the IEEE standard 112-method B test.

In this paper, we analyze the influence of the uncertainties on the behavior constitutive laws of ferromagnetic materials on the behavior of a turboalternator. A simple stochastic model of anhysteretic nonlinear B(H) curve is proposed for the ferromagnetic yokes of the stator and the rotor. The B(H) curve is defined by five random parameters. We quantify the influence of the variability of these five parameters on the flux linkage of one phase of the stator winding depending on the excitation current I. The influence of each parameter is analyzed via the Sobol indices. With this analysis, we can determine the most influential parameters for each state of magnetization (according to the level of I) and investigate where the characterization process of the B(H) curve should focus to improve the accuracy of the computed flux linkage.

Abstract—The presented paper proposes a topology optimisation methodology based on the density-based method SIMP, and applied to a numerical example to validate the former. The approach and methodology are detailed, and the results for a 3D basic electromagnetic example are presented. The non-linear B(H) curve is also taken into account. Index Terms—gradient-based algorithm, relaxation of variables, SIMP density method, weighted objective sum

Organizing international conferences leads to significant amounts of emitted greenhouse gases (GHG’s). This is mainly due to the transport of the attendees to the conference venue. At IEEE-VPPC’14, actions were taken to reduce and to compensate the conference GHG emissions as well as to raise public awareness. This paper describes these actions and presents a quantitative estimation of the GHG sources related to the conference.

Organizing international conferences leads to emission of greenhouse gases (GHG). Even though, some conferences are devoted to “greener” systems (e.g. IEEE VPPC), the transport of attendees and the local organization of the conference are not “carbon free”. Consequently, some experiences are reported in this paper in order to reduce the ecological footprint of the conference itself and also to mitigate the emitted GHG for international congresses.

The parallelization of numerical simulation algorithms, i.e., their adaptation to parallel processing architectures, is an aim to reach in order to hinder exorbitant execution times. The parallelism has been imposed at the level of processor architectures and graphics cards are now used for general-purpose calculation, also known as “General-Purpose computation on Graphics Processing Unit (GPGPU)”. The clear benefit is the excellent performance over price ratio. Besides hiding the low level programming, software engineering leads to a faster and more secure application development. This paper presents the real interest of using GPU processors to increase performance of larger problems which concern electrical machines simulation. Indeed, we show that our auto-generated code applied to several models allows achieving speedups of the order of 10x.

Cette communication présente une méthode pour discrétiser la densité de courant, en imposant une divergence nulle et en minimisant l’erreur par rapport à la densité de courant exacte et uniforme.