Kevin Darques, Abdelmounaïm Tounzi, Yvonnick Le-menach and Karim Beddek
This paper aims to go deeper on the analysis of the shaft voltage of large turbogenerators. The main interest of this study is the investigation process developed.
Abstract
Purpose
This paper aims to go deeper on the analysis of the shaft voltage of large turbogenerators. The main interest of this study is the investigation process developed.
Design/methodology/approach
The analysis of the shaft voltage because of several defects is based on a two-dimensional (2D) finite element modeling. This 2D finite element model is used to determine the shaft voltage because of eccentricities or rotor short-circuit.
Findings
Dynamic eccentricities and rotor short circuit do not have an inherent impact on the shaft voltage. Circulating currents in the stator winding because of defects impact the shaft voltage.
Originality/value
The original value of this paper is the investigation process developed. This study proposes to quantify the impact of a smooth stator and then to explore the contribution of the real stator winding on the shaft voltage.
Details
Keywords
Leysmir Adriana Millan Mirabal, Oualid Messal, Abdelkader Benabou, Yvonnick Le Menach, Loic Chevallier, Jean-Yves Roger and Jean-Pierre Ducreux
The purpose of this study is to explore the effect of the demagnetizing field in the Epstein characterization of grain-oriented electrical steels through a finite element method…
Abstract
Purpose
The purpose of this study is to explore the effect of the demagnetizing field in the Epstein characterization of grain-oriented electrical steels through a finite element method (FEM) simulations.
Design/methodology/approach
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.
Findings
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.
Originality/value
Both stacking configurations (parallel and cross) of the Epstein frame are analyzed by three-dimensional finite element simulation.
Details
Keywords
Yvonnick Le Menach, Stéphane Clénet and Francis Piriou
This paper presents a method of coupling magnetostatic potential formulations with electrical circuits for the 3D FEM. Allowing for the current density distribution in stranded…
Abstract
This paper presents a method of coupling magnetostatic potential formulations with electrical circuits for the 3D FEM. Allowing for the current density distribution in stranded conductors, two vectors N and K are introduced. A systematic method of decomposing both vectors in Whitney’s element spaces is suggested. This method can be used for coils with a complex shape. As an example of application a three‐phase transformer is studied.
Details
Keywords
Abdellatif Tinzefte, Yvonnick Le Menach, Julien Korecki and Francis Piriou
The purpose of this paper is to develop a solving method based on the parallelization of the calculus of the finite integration technique on many processors and discuss its…
Abstract
Purpose
The purpose of this paper is to develop a solving method based on the parallelization of the calculus of the finite integration technique on many processors and discuss its efficiency following the number of processors.
Design/methodology/approach
The finite integration technique is used in different engineering domains as well as to compute the electromagnetic phenomena. This technique is efficient and generates a linear system with regular structure, this system can be implemented and solved in parallel with a direct solver. In fact, in reordering the unknowns by the nested dissection method, the lower triangular matrix of the Cholesky factorization can be constructed with many processors without assembling the matrix system.
Findings
This paper deals with the parallelization of the finite integration technique which is performed by data partitioning and leads to a high‐performance.
Originality/value
The paper presents a parallel implementation of the finite integration technique associated to a direct solver which is practical and efficient.
Details
Keywords
Xiaodong Shi, Yvonnick Le Menach, Jean‐Pierre Ducreux and Francis Piriou
To compare slip surface and moving band techniques for modelling movement in 3D with FEM.
Abstract
Purpose
To compare slip surface and moving band techniques for modelling movement in 3D with FEM.
Design/methodology/approach
The slip surface and moving band techniques are used to model the rotation of electrical machines in 3D with FEM. The proposed techniques are applied to a permanent magnet synchronous machine. The comparison is carried out at no‐load for the electromotive force (EMF) and the cogging torque. The torque is also compared for the short circuit case.
Findings
For both the locked‐step and moving band approaches there is no difficulty in establishing the scalar potential and potential vector formulations. However, if step displacement is not equal to the mesh step, the results can show numerical irregularities. Some improvements have been proposed in order to limit this problem.
Originality/value
The results of the EMF and the cogging torque are improved.
Details
Keywords
Zuqi Tang, Yvonnick Le Menach, Emmanuel Creuse, Serge Nicaise, Francis Piriou and Nicolas Nemitz
In this paper, the aim is to propose a residual‐based error estimator to evaluate the numerical error induced by the computation of the electromagnetic systems using a finite…
Abstract
Purpose
In this paper, the aim is to propose a residual‐based error estimator to evaluate the numerical error induced by the computation of the electromagnetic systems using a finite element method in the case of the harmonic A‐φ formulation.
Design/methodology/approach
The residual based error estimator used in this paper verifies the mathematical property of global and local error estimation (reliability and efficiency).
Findings
This estimator used is based on the evaluation of quantities weakly verified in the case of harmonic A‐φ formulation.
Originality/value
In this paper, it is shown that the proposed estimator, based on the mathematical developments, is hardness in the case of the typical applications.
Details
Keywords
Zuqi Tang, Yvonnick Le-menach, E. Creusé, S. Nicaise, F. Piriou and N. Némitz
The purpose of this paper is to propose some a posteriori residual error estimators (REEs)to evaluate the accuracy of the finite element method for quasi-static electromagnetic…
Abstract
Purpose
The purpose of this paper is to propose some a posteriori residual error estimators (REEs)to evaluate the accuracy of the finite element method for quasi-static electromagnetic problems with mixed boundary conditions. Both classical magnetodynamic A-ϕ and T-Ω formulations in harmonic case are analysed. As an example of application the estimated error maps of an electromagnetic system are studied. At last, a remeshing process is done according to the estimated error maps.
Design/methodology/approach
The paper proposes to analyze the efficiency of numerical REEs in the case of magnetodynamic harmonic formulations. The deal is to determine the areas where it is necessary to improve the mesh. Moreover the error estimators are applied for structures with mixed boundary conditions.
Findings
The studied application shows the possibilities of the residual error estimators in the case of electromagnetic structures. The comparison of the remeshed show the improvement of the obtained solution when the authors compare with a reference one.
Research limitations/implications
The paper provides some interesting results in the case of magnetodynamic harmonic formulations in terms of potentials. Both classical formulations are studied.
Practical implications
The paper provides some informations to develop the proposed formulations in the software using finite element method.
Social implications
The paper deals with the possibility to improve the determination of the meshes in the analysis of electromagnetic structure with the finite element method. The proposed method can be a good solution to obtain an optimal mesh for a given numerical error.
Originality/value
The paper proposes some elements of solution for the numerical analysis of electromagnetic structures. More particularly the results can be used to determine the good meshes of the finite element method.