A Micro Magnetic Bearing With A 2 mm-Diameter Rotor And Its Performance

A novel micro-magnetic bearing (MMB) with a 2 mm-diameter rotor is discussed. The MMB has a simple structure and consists of some mechanical parts and a permanent magnet. The rotor is supported by magnetic couplings generated by the permanent magnet and is stabilized by a one-axis-controller. The MMB for the 2 mm-diameter rotor was constructed, such that the rotor could be levitated without mechanical contact and which could rotate at 39,000 rpm. The static and dynamic characteristics of the MMB are evaluated. The measured magnetic stiffness in the passively controlled radial and angular directions was 4.7 N/mm and 2.7 × 10-2 Nm/rad, respectively. The total power consumption and copper loss without rotation were 20.4 mW and 17.2 mW, respectively.