Design of a Three Phase Permanent Magnet Biased Radial Active Magnetic Bearing Regarding a Position Sensorless Control

A novel design of a radial active magnetic bearing with a permanent magnet bias flux will be presented. The arrangement with only three stator coils allows for an utilization of a standard three phase voltage source inverter. The control coils themselves will be used for the detection of the rotor position with two degrees of freedom. Hence, no external position sensor has to be used resulting in a robust and cheap application of the active radial magnetic bearing. Analytical calculations using designated magnetic flux paths, 3D finite element analyses as well as measurement results are compared regarding the influence of the rotor position on the electromagnetic bearing parameters. Additionally, first measurement results of the sensorless position detection method are presented for a verification in principle. Finally a sensorless control of the hybrid radial magnetic bearing will be obtained.