Abstract
High-speed motor drive for turbo compressors is becoming attractive, but there is a rotor dynamics problem due to the lowered bending mode frequencies. In order to support such flexible and high-speed rotating shaft, active magnetic bearing will be one of the solutions. In this paper, the design and test results of active magnetic control system for a high-speed turbo compressor that has two impellers and a motor on a single shaft are presented. In a digital control, a large phase lag in high frequency domain cannot be avoided. For this disadvantage, a practical controller design that use phase shifting filters is presented. In addition to this, a synchronous filter that has an arbitrary phase property at the reference frequency is applied to the controller to cross over the first bending critical speed. Adopting these control methods, very stable operation at the rated speed of 55,000min^<-1> is realized.
