A method and a controller for controlling a magnetic bearing device, in
which a rotor is suspended for rotation around a shaft, are disclosed.
Sensor signals are transformed to yield tilt displacement signals
(S.theta.x, S.theta.y) which correspond to tilting displacements of the
shaft in predetermined directions (x, y). From the tilt displacement
signals (S.theta.x, S.theta.y), tilt control signals A.theta.x,
A.theta.y) are derived; these are transformed to yield actuator control
signals for driving electromagnetic actuators in the magnetic bearing
device. According to the invention, tilting displacements for which the
tilt vector rotates about the device axis (z) with a first predetermined
sense of rotation are controlled separately from tilting displacements
for which the tilt direction vector rotates about the device axis (z)
with a second sense of rotation opposite to the first predetermined sense
of rotation. In this way, control of nutation and precession can be
achieved without influence from blade vibrations or shaft bending modes.