Sensorless Control for a Three-pole Active Magnetic Bearing System

This study proposes a novel sensorless control of a current-controlled three-pole active magnetic bearing (AMB) system. It is based on the smooth current controller incorporated with the estimated rotor displacements. The rotor position information is extracted from additional sensing coil currents. The sensing coil currents are generated from three phase voltages injected to the additional coils on each magnetic pole. The dynamic model of the 3-pole AMB with the additional high frequency input is derived for levitation control and for position estimation. The results are verified through simulation analysis.