Development of one-axis controlled bearingless motor and its application to a centrifugal pump for extremely low temperature

Abstract

In this paper, a centrifugal pump for for extremely low temperature was fabricated and evaluated by experiments in liquid nitrogen. The pump is using a bearingless motor and permanent magnet bearings to levitate and rotate the rotor without lubricating oil. The difference from the conventional study is that a one-axis controlled bearingless motor is used to reduce the magnetic bearing cost and that the bearings are installed in the liquid to eliminate a shaft-seal. Stable levitation and rotation of the rotor were confirmed in the rotation and pump experiments in liquid nitrogen. In pump experiment, the flow rate of liquid nitrogen was measured at 1 cm in a pumping height. The maximum flow rate was 1.3 L/min when the rotation speed is 1,800 rpm.

High Precision Magnetic Levitation Actuator for Micro-EDM

“…Tong Zheng et al [22] designed a sizing optimization method to determine the magnetic levitation actuator for a rotary table and validated the effectiveness and accuracy of the method using simulation followed by experiments. Hirohisa Kato et al [23] designed and fabricated a centrifugal pump using bearingless electrodes and permanent magnetic bearings to levitate and rotate the rotor in extremely low-temperature environments. Iwanori Murakami et al [24] designed a superconducting magnetic bearing that combines a superconducting magnetic levitation system with a repulsive magnetic levitation system, which has a strong axial levitation force and can overcome resonance.…”