Affiliations: [a] Ritsumeikan University, Kusatsu, Shiga, Japan | [b] University of Tokyo, Kashiwa, Chiba, Japan | Université Laval, Canada | Tohoku University, Japan
Correspondence:
[*]
Corresponding author: Satoshi Ueno, Department of Mechanical
Engineering College of Science and Technology, Ritsumeikan University, 1-1-1
Nojihigashi, Kusatsu, Shiga, Japan. E-mail: [email protected]
Abstract: Superconducting technology has been significantly improved since the
superconductor Y-Ba-Cu-O was discovered. This technology has been applied to
many medical image-processing applications such as magnetoencephalogram (MEG)
and magnetic resonance imaging (MRI). Because the superconducting phenomenon
occurs at extremely low temperatures, liquid helium or liquid hydrogen is
essential to obtain a low-temperature environment. In addition, it is well
known that the decompression of the liquid helium creates superfluid helium.
This phenomenon improves the performance of the superconducting devices. For
that reason, a vacuum pump, which can be used at a cryostat, is required. In this paper, we propose a motor that has a small size and simple
structure for use in the cryostat. The proposed motor consists of an axial
self-bearing motor, superconducting magnetic bearings, and permanent-magnet
repulsive-type passive magnetic bearings. The design of the motor and control
method is introduced. The experimental results show that the proposed motor has
a high possibility for high-speed rotation at extremely low temperatures.
Keywords: Rotary machinery, magnetic bearing, superconducting magnetic bearing, vacuum pump
