Importance

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Abstract

A bearing for radially and axially holding a rotor with large radial dimensions about a stator has sensors (22-25) for determining tilt angles of the rotor with respect to the stator's X and Y axes, and controllers for generating control currents in control coils (17-20) associated with the stator's X and Y axes. The generated currents depend on the output signal of the sensors and, in combination with permanent magnet rings arranged on rotor, exert moments on the rotor, influencing the tilt angles. The controllers have alternating couplers which disable the connection of the tilt axes generated by gyroscopic effects. The controllers may include proportional-derivitive controllers having a gain which is modified proportionately to the square of the speed of the rotor, and a time constant which changes in inverse proportion to the rotor's speed. The central bearing for the radial movement in the X/Y direction either acts passively as a permanent magnet, or actively, as an electromagnet. In the latter case, the parameters of the controllers can be switched from a 'soft' to a 'hard' operational mode and vice-versa, either to prevent unbalanced disturbances from affecting the stator, or to provide sufficient rigidity for the position control function, even in the presence of external forces.

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First Claim