Variable Space Vector Modulation for Self-Sensing Magnetic Bearings

The subject of this paper is an improvement of a selfsensing control of a three-phase radial magnetic bearing based on the so called INFORM method. The focus of this paper lies on a modification of the space vector modulation to achieve a high position resolution as well as a high actuator dynamic at low DClink voltage levels. Therefore, certain constraints for the space vector modulation must be fulfilled to allow a self-sensing operation of the bearing. For this reason, different kinds of space vector modulations are designed theoretically as well as proven in experiments on a prototype of a radial magnetic bearing. Finally, the obtained performance of the INFORM method is shown by a linearity measurement and a comparison of the small signal behavior by means of external position sensors.