Predetermination of Currents and Field in Short-Circuit Voltage Operation for an Axial-Flux Permanent Magnet Machine

Risk of irreversible magnet demagnetization during short-circuit fault is analyzed in case of an axial-flux dual-rotor machine, using a three-dimensional finite-element method (3D-FEM). In order to validate the numerical model, calculated waveforms of the currents are compared with experimental results for short-circuit at low speeds. Then currents and magnetic flux density inside the magnets are computed for short-circuit at higher speeds in order to predetermine the maximum admissible speed for the machine

Two Guaranteed Equilibrated Error Estimators for Harmonic Formulations in Eddy Current Problems

International audienceIn this paper, two guaranteed equilibrated error estimators are proposed and compared for the 3D harmonic magnetodynamic problem of Maxwell's system. This system is recasted in the classical A − ϕ potential formulation or, equivalently , in the T − Ω potential formulation, and it is solved by the Finite Element method. The first equilibrated estimator presented is built starting from these two complementary problems, the other one is built starting from the A − ϕ numerical solution uniquely by a flux reconstruction technique. The equivalence between errors and estimators is established. Afterwards, an analytical benchmark test illustrates the obtained theoretical results and a physical benchmark test shows the efficiency of these two estimators

Parallel Direct Solver for the Finite Integration Technique in Electrokinetic Problems

International audienceThe finite integration technique allows the simulation of real-world electromagnetic field problems with complex geometries. It provides a discrete reformulation of Maxwell's equations in their integral form suitable for numerical computing. The resulting matrix equations of the discretized fields can be used for efficient numerical simulations on modern computers and can be exploited to use a parallel computing. In fact, by reordering the unknowns by the nested dissection method, it is possible to directly construct the lower triangular matrix of the Cholesky factorization with many processors without assembling the matrix system. In this paper, a parallel algorithm is proposed for the direct solution of large sparse linear systems with the finite integration technique. This direct solver has the advantage of handling singularities in the matrix of linear systems. The computational effort for these linear systems, often encountered in numerical simulation of electromagnetic phenomena by finite integration technique, is very significant in terms of run-time and memory requirements. Many numerical tests have been carried out to evaluate the performance of the parallel direct solver. Index Terms—Finite element methods, finite integration technique, linear systems, numerical analysis, parallel algorithms

Residual-based a posteriori estimators for the A/phi magnetodynamic harmonic formulation of the Maxwell system

International audienceThis paper is devoted to the derivation of an a posteriori residual-based error estimator for the A/phi magnetodynamic harmonic formulation of the Maxwell system. The weak continuous and discrete formulations are established, and the well-posedness of both of them is addressed. Some useful analytical tools are derived. Among them, an ad-hoc Helmholtz decomposition is proven, which allows to pertinently split the error. Consequently, an a posteriori error estimator is obtained, which is proven to be reliable and locally efficient. Finally, numerical tests confirm the theoretical results

Canal lock variable speed hydropower turbine design and control

The design of a novel submerged hydraulic turbine for producing electricity by converting the available hydropower on canal locks during raising and lowering ships, but with the minimum overall impact on the facility, is being considered. The hydraulic head in such applications is low (few meters) and varies over time (from its maximum value down to zero) resulting in a low potential conversion of hydraulic head in electrical energy. The study involves the modification of the hydraulic transient system, the design and performance estimation of a hydraulic turbine. Based on the performance curves, a permanent magnet Vernier generator is designed. The models of hydraulic turbine and generator are added to the system model and simulations results of the whole system are presented.Region Hauts de Franc

Quantitative Design of a High Performance Permanent Magnet Vernier Generator

Permanent-magnet vernier machines are becoming more and more attractive due to their high torque density and low-speed operating capabilities. This paper investigates the effects of the magnet thickness, magnet pole arc ratio, and slot open ratio on the torque capacity. An analytical model is first presented. It is validated by comparing the results with the finite-element analysis (FEA) under the same hypothesis. A mono-objective optimization is then conducted on the basis of the analytical model coupled to genetic algorithm to reach the optimal values yielding the highest value of the torque. Finally, the influence of nonlinear magnetic material behavior on the optimal design is investigated through nonlinear FEA. The results are presented and discussedRegion Hauts de France EDF VN

Design and Study of a Multi-phase Axial-flux machine

Adresse URL de l'éditeur http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1608484&isnumber=33780 Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, a 7-phase Axial-flux Double-rotor Permanent Magnet Synchronous Machine is studied using analytical and Finite Element methods. This type of machine shows a higher sensitivity to the inductance harmonics and electromotive force (emf) compared with the 3-phase machines. So, the conventional analytical modeling method, in which only the first harmonic is taken into account, leads to significant errors in the determination of the control parameters, e.g. the frequency of Pulse Width Modulation Voltage Source Inverter. A multi-machine model explains the reasons for this sensitivity and a more sophisticated analytical method is used. Results are compared with those obtained by the 3-D FEMCNRT Genie Electrique/ Region Nord Pas de Calais/FEDER/FUTURELEC

Design and Study of a Multi-phase Axial-flux machine

Adresse URL de l'éditeur http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1608484&isnumber=33780 Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, a 7-phase Axial-flux Double-rotor Permanent Magnet Synchronous Machine is studied using analytical and Finite Element methods. This type of machine shows a higher sensitivity to the inductance harmonics and electromotive force (emf) compared with the 3-phase machines. So, the conventional analytical modeling method, in which only the first harmonic is taken into account, leads to significant errors in the determination of the control parameters, e.g. the frequency of Pulse Width Modulation Voltage Source Inverter. A multi-machine model explains the reasons for this sensitivity and a more sophisticated analytical method is used. Results are compared with those obtained by the 3-D FEMCNRT Genie Electrique/ Region Nord Pas de Calais/FEDER/FUTURELEC

Contribution à la simulation du mouvement en 3D avec la méthode des éléments finis, appliquée à la modélisation des machines électriques

LILLE1-BU (590092102) / SudocSudocFranceF