Design of systems and components for high-speed electric propulsion systems

This PhD dissertation presents the modelling and design of a novel High Speed (HS) Electric Propulsion System (EPS) for automotive application. In particular, Chapter I presents a comparison among different EPS configurations, which are designed by combining different Permanent Magnet Synchronous Machines (PMSMs) with the corresponding most suitable transmission system; this is done in order to investigate the competitiveness of HS-EPS for automotive applications. Subsequently, the design of a novel ferrite-based HS-PMSM suitable for automotive application is presented in Chapter II. The design has been carried out through a novel multi-parameter analytical design procedure, which has been developed with the aim of achieving a preliminary machine design that considers both design targets and constraints. This preliminary design has been then validated through accurate and extensive finite element analyses, which regard both mechanical and electromagnetic performances. In order to guarantee appropriate coupling between the designed HS-PMSM and vehicle wheels, the design and optimization of a novel coaxial Magnetic Gear Transmission (MaGT) is presented in Chapter III. In particular, a single-stage MaGT is designed at first in accordance with mechanical and magnetic analytical models. However, as far as a very high gear ratio is required (more than 20), the design of a double-stage MaGT has been carried out, which addresses some of the issues arising from the single-stage solution. A comparison in terms of performances and sizes between the two designed MaGTs is thus presented and discussed: the results obtained through the analytical models are validated by means of accurate finite element analyses. Subsequently, a further optimization of the double-stage MaGT has been carried out, which aims at reducing the harmonic content of the magnetic flux density. A comparative study between the two double stage MaGTs is presented and discussed, especially with reference to core losses and temperature distribution, highlighting the improved performances achieved by the optimized configuration.