Selection of Magnetic Materials for Bearingless High Speed Mobile Flywheel Energy Storage Systems

Beside a higher amount of reactive power and a lower power to weight ratio compared with other machine types, the switched reluctance motor (SRM) features robustness, low cost, failure tolerance, and a wide operation temperature range. With additional power electronics and construction effort, the SRM can be operated as a bearingless drive. This is important to increase the lifetime of bearings in vacuum since their lubrication is difficult. In this paper, the technical potential of this particular motor topology to produce torque and radial force is evaluated based on finite element simulations. Additionally, the estimated hysteresis and eddy current losses during the normal and bearingless drive operation depending on the selected soft magnetic materials are evaluated.