Stabilization of a Superconducting Magnetic Bearing for Ring Spinning at Low-Speed Operation

Recent studies have demonstrated the potential for the application of superconducting magnetic bearings (SMB) in textile machines. In this work, we study the dynamic behavior of a high-speed SMB, which was designed for a ring spinning process with an operational speed of up to 50 000 rpm. Previous investigations indicated that the inherently low damping coefficient of such a SMB setup may lead to radial large amplitude resonance-induced oscillations, which were observed during both acceleration and deceleration phases. To investigate these phenomena in more detail, an experimental setup was built to analyze the behavior of the permanent magnet (PM) ring for lower rotational speeds (up to 5 000 rpm), at which the first resonance occurs. Non-contact distance sensors were employed to monitor the motion of the levitating PM ring in real time. This allows to determine the oscillation amplitude and the resonance frequency. To mitigate the vibration associated with resonance, copper plates with varying thicknesses were implemented as passive eddy current dampers. The amplitude of the oscillations was significantly reduced with these damping elements.