Design of active magnetic bearing rotors and their control method for passing through fourth bending critical speed

Abstract

These days, centrifugal compressors and other industrial turbomachines tend to be faster, downsized, and reduced in cost. If a technology can be established for operation of machines over higher critical speed using an active magnetic bearing, the number of impellers per casing can be increased, allowing downsizing and cost reduction of trains. In this study, experimental equipment of a flexible rotor supported by active magnetic bearings was developed to carry out experiments as a step toward developing the technology. The following results were obtained, (1) Mass distribution in designing flexible rotors allows adjustment of the critical speed by design. (2) With the modal balancing method under higher critical speed, the sixth critical speed was passed through, the world's first achievement of this.