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Sizing an electrical machine can simply be achieved by introducing the concepts of electric loading and magnetic loading . The aim is to predict the main dimensions of the active parts such as windings, magnetic circuits, slots and magnets [1-3]. This analytical sizing requires less computational effort compared to numerical computations [4] while the precision remains acceptable. In the frame of IMOTHEP project [5], several configurations of hybrid-electric propulsion aircrafts with different electrical power requirements are considered. It was then necessary to design electric generators coupled to a turbomachine whose data are given by other partners in the project. For this purpose, we have developed a computational tool under the open source spreadsheet application OpenOffice Calc [6]. This choice was encouraged by the fact that a collaborative work on spreadsheets allows different users to easily share and integrate new data. This brings some comfort in carrying out the needed repetitive calculations. Furthermore, Calcs solver allows performing in a very simple way single objective constrained optimizations problems using metaheuristic algorithms. We have then conducted many optimizations whose objective was the reduction of the machine mass to increase power to weight density of surface mounted permanent magnets (PMSM) machines. The developed computational tool integrates the following features related to the PMSM design: - Electromagnetic sizing by means of analytical models based on the resolution of 2D magnetostatic problems in the air gap of the PMSM [7] - Winding temperature evaluation based on a lumped parameter thermal model [8] - Evaluation of magnets retaining sleeve thickness of high-speed PMSM based on simple mechanical design [9] These features can be evaluated separately or coupled in a multi-physics way to ensure a robust optimized design of the machine. Only few minutes are required to get the results. Several design examples will be provided and compared to finite element computations. References [1] J. Pyrhonen, T. Jokinen, and V. Hrabovcova, Design of rotating electrical machines, 1st edition, John Wiley Sons, 2008, 512 p. [2] I. Boldea, and S. A. Nasar, The Induction Machines Design Hand-book, 2nd edition, CRC Press, 2009, 845 p. [3] B. Laporte, Machines electriques tournantes Conception, dimensionnement, fonctionnement, 1st Edition, Ellipses-Technosup, 2007, 370 p. [4] http://www.femm.info/ [5] https://www.imothep-project.eu/ [6] https://www.openoffice.org/product/calc.html [7] Z. Q. Zhu, D. Howe, E. Bolte and B. Ackermann, \"Instantaneous magnetic field distribution in brushless permanent magnet DC motors. I. Open-circuit field,\" IEEE Transactions on Magnetics, vol. 29, no. 1, pp. 124-135, Jan. 1993. [8] P. H. Mellor, D. Roberts, and D. R. Turner, \"Lumped parameter thermal model for electrical machines of TEFC design,\" IEE Proceedings-B, vol. 138, no. 5, pp. 205-218, Sept. 1991. [9] A. Binder, T. Schneider and M. Klohr, \"Fixation of buried and surface-mounted magnets in high-speed permanent-magnet synchronous machines,\" IEEE Transactions on Industry Applications, vol. 42, no. 4, pp. 1031-1037, July-Aug. 2006. |
