Rotor losses have a major impact on the performance of high-speed permanent magnet synchronous machines. Therefore a way to reduce rotor losses by using shielding cylinders is proposed and the effects of these measure are discussed according to the main causes of the rotor losses, which are current harmonics and winding harmonics. The loss minimisation will be demonstrated a for a specific high-speed motor design.
Thrust magnetic bearing characteristics are frequency dependent due to the eddy-currents inducted inside magnetic parts that oppose any change of magnetic flux in the inner parts. When used as linear actuator for vibration assisted drilling in industrial production, eddy-currents limit the maximum achievable stroke and vibration frequency with active thrust bearing. This reduces tool-feed rate or shortens tool average useful life. After introducing the problem, material properties and shape optimization are evaluated and compared in the frequency range of interest for vibration assisted drilling. While material properties are determinant, mechanical constraints often limit the selection to materials with significant electrical conductivity. Eddy-current effect can only be partially mitigated with shape optimization.