Rotor Disturbance Attenuation using H-inf Controller for Active Magnetic Bearings

The purpose of this paper is to demonstrate the performance of an H= optimized controller for a magnetic bearing, in theory and experimentally. The application of magnetic bearings to practical rotating machinery is becoming more and more widespread in recent years. Often, machinery is operated under conditions different from the design point, such as compressors or pumps at low load conditions, which results in high fluid loads at low frequency. These forces may create vibration problems. This paper develops a control methodology to stabilize the magnetic bearing/rotor control loop, in the presence of uncer tainty, and minimize the worst-case excursion of rotor vibrations due to low frequency d, isturbances. The results are compared to an equivalent PD controller.