Impact of Stray Fields Due to the Structural Integration of a Linear Synchronous Machine for Hyperloop Technology

The hyperloop technology presents an opportunity for low-energy consumption high-speed transport, thanks to a reduction of air pressure within a tube-guided transport mode. This chapter focuses on the integration of a propulsion system in the tube, regarding its mechanical and electro-magnetic aspects. The structure for connecting the propulsion motor to the surrounding tube is designed for the loads that the machine needs to withstand, at all exploitation speeds up to 1000 km/h. The connection of the stator housing to the tube has a stray field impact linked to the position of the connecting ribs. When the rib is located behind a stator slot, some more flux penetration into the rib is noted, compared to when it is located behind a stator tooth. The impact of the structure on force development and losses in the motor are verified, comparing 2D with 3D Finite Element methods, implemented in JMAG. Regarding the prediction of magnetic flux in the stator and the generated propulsion force, excellent agreement is obtained. The 3D model predicts higher losses than 2D models, due to additional structural components and stray fields at the end of the stator stack. Losses in the structural components are significant but smaller than core losses in the stator yoke, due to the large lamination thickness used. At high speeds, the core losses in stator laminations were calculated using a 3D model of a single lamination, in order to model the skin effect. This results in a higher eddy-current level than the simplified 2D approach suggests.