A Finite Element Simulation Tool for Predicting Hysteresis Losses in Superconductors Using an H-Oriented Formulation with Cohomology Basis Functions
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Currently, modelling hysteresis losses in superconductors is most often based on the H-formulation of the eddy current model (ECM) solved using the finite element method (FEM). In the H-formulation, the problem is expressed using the magnetic field intensity H and discretized using edge elements in the whole domain. Even though this approach is well established, it uses unnecessary degrees of freedom (DOFs) and introduces modelling error such as currents flowing in air regions due to finite air resistivity. In this paper, we present a modelling tool utilizing another H-oriented formulation of the ECM, making use of cohomology of the air regions. We constrain the net currents through the conductors by fixing the DOFs related to the so-called cohomology basis functions. As air regions will be truly non-conducting, DOFs and running times of these nonlinear simulations are reduced significantly as compared to the classical H-formulation. This fact is demonstrated through numerical simulations.
KeywordsSuperconductors Hysteresis losses Finite element method Cohomology
This research was partially supported by The Academy of Finland project #250652. Most of the work leading to this research was conducted during the research exchange period of Valtteri Lahtinen 19.8.2013–15.2.2014 at École Polytechnique de Montréal, Montréal, Canada.
- 2.Grilli, F., Pardo, E., Stenvall, A., Nguyen, D.N., Yuan, W., Gömöry F.: IEEE Trans. Appl. Supercond. 24, 8200433 (2014)Google Scholar
- 9.Comsol Multiphysics is a commercial FEM program. http://www.comsol.com
- 12.Frankel, T.: The geometry of physics: An introduction third edition Cambridge. Cambridge University Press, UK (2012)Google Scholar
- 19.Nash, C., Sen, S.: Topology and Geometry for Physicists. Academic Press, Orlando (1987)Google Scholar
- 21.Pellikka, M., Tarhasaari, T., Suuriniemi, S., Kettunen, L.: J. Comp. Appl. Math 246, 225Google Scholar
- 27.Pardo, E., Šouc, J., Kovač, J.: Supercond. Sci. Technol. 25, 035–003 (2012)Google Scholar
- 29.Lyly, M., Lahtinen, V., Stenvall, A., Tarhasaari, T., Mikkonen, R.: Approaches for tree - co-tree gauged T−φ formulated eddy current problem in superconductor hysteresis loss simulations. IEEE Trans. Appl. Supercond. 23 (8200909) (2013)Google Scholar
- 30.Kurz, S., Auchmann, B.: Fast Boundary Element Methods in Engineering and Industrial Applications: Lecture notes in Applied and Computational Mechanics, vol. 63, pp 1–62 (2012)Google Scholar