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Mechanical and Thermal Design of Electrically Excited Synchronous Machines for Traction Applications

Alessio Bergano

Mechanical and Thermal Design of Electrically Excited Synchronous Machines for Traction Applications.

Rel. Andrea Tonoli, Renato Galluzzi, Irving Sixto Aguilar Zamorate. Politecnico di Torino, Corso di laurea magistrale in Mechatronic Engineering (Ingegneria Meccatronica), 2025

Abstract:

In the automotive field, a common solution utilized for electric vehicles consists in the use of permanent magnet synchronous motors (PMSM), however this is not sustainable due to the presence of rare earths in them. The scarcity of these materials combined with their widespread use in various technological sectors have highlighted the criticality of continuing to use this configuration, shifting the interest of automotive manufacturers towards alternative solutions that avoid the use of rare earth materials. One of these, adopted by car manufacturers such as Renault and BMW, consists in replacing the PMSM with a wound rotor one (EESM or WFSM) whose performance is however inferior. In particular, considering that the wound rotor motor presents structural and thermal limitation for high-speed applications, the objective of the thesis is the attempt to design a WFSM that can operate at speeds higher than 15 krpm while maintaining the performances of PMSM. Using MotorCAD software, an electromagnetic analysis was performed to increase the torque produced while minimizing the torque ripple. To do this, a pre-existing IPM motor with power in the order of 30 kW has been used as starting model. The stator of the starting model has been maintained, instead the permanent magnets have been removed replacing the rotor with a wound model. The geometry of the cross sectional area of the latter has then been optimized, in order to reproduce the performance of the starting configuration, but using the dimensions of the airgap and shaft as geometric boundaries. The geometric optimization was performed through a PSO (particle swarm) optimization algorithm using the communication between the MotorCAD and Matlab softwares. Once the rotor geometry was obtained, the mechanical analysis was carried out to verify that the stresses generated by the centrifugal force did not exceed the limit of the material. The analyses were conducted using MotorCAD for 2D modeling and Comsol Multiphysics for 3D modeling, verifying how the addition of an external component could reduce the stresses applied to the rotor. Subsequently, it was found that using a cooling system composed of simple solutions such as cooling jacket and forced air cooling it is possible to reduce the engine temperature making it suitable for high-speed applications. For these analyses, the MotorCAD and Comsol Multiphysics software were used again. The final model is a tradeoff between the electromagnetic, mechanical and thermal design. The motor obtained can operate at the target speed with a similar efficiency to the PMSM, but the design wasn’t able to achieve the torque requirements of the starting model due to current and thermal constraints.

Relatori: Andrea Tonoli, Renato Galluzzi, Irving Sixto Aguilar Zamorate
Anno accademico: 2024/25
Tipo di pubblicazione: Elettronica
Numero di pagine: 97
Informazioni aggiuntive: Tesi secretata. Fulltext non presente
Soggetti:
Corso di laurea: Corso di laurea magistrale in Mechatronic Engineering (Ingegneria Meccatronica)
Classe di laurea: Nuovo ordinamento > Laurea magistrale > LM-25 - INGEGNERIA DELL'AUTOMAZIONE
Aziende collaboratrici: NON SPECIFICATO
URI: http://webthesis.biblio.polito.it/id/eprint/36492
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