Design of rotor and magnetic bearings for 200RT class turbo refrigerant compressor

Abstract

For turbo refrigerant compressor, oil-free bearing has merits that the continuous operation is possible because the lubrication system is not required and the refrigerant is not contaminated by the oil. Magnetic bearing is one of oil-free bearing and recently it started to be applied to a few turbo refrigerant compressors because of easy maintenance thanks to no friction and no wear in bearing. 200RT class turbo refrigerant compressor using oil-free bearing is under development after finishing the development of 145RT compressor. This paper presents the design modification from 145RT compressor and design procedure of hybrid thrust magnetic bearing using both of permanent magnet and electromagnet. Thrust magnetic bearing are designed to support 2,000N thrust force by compressor at 18,000rpm operating speed. The controller for magnetic bearing was designed and the rotordynamic analysis such as critical speed, and unbalance response in case that the rotor is supported by magnetic bearings are simulated by using finite-element method. © 2013 Springer-Verlag.