Design of multi-input multi-output controller for magnetic bearing which suspends helium gas-turbine generator rotor for high temperature gas cooled reactor

Takada, Shoji; Funatake, Yoshio; Inagaki, Yoshiyuki

A design method of a multi-input multi-output controller, which links magnetic forces of multiple magnetic bearings by feedback of multiple measurement values of vibration of a rotor, was proposed for the radial magnetic bearings for the generator rotor of helium gas turbine with a power output of 300 MWe. The generator rotor is a flexible rotor, which passes over the forth critical speed. A controller transfer function was derived to reduce a modeling error at the forth critical speed, in which the bending vibration mode is similar to the one which is excited by unbalance mass. A 1404th order un-symmetric coefficient matrix of equation of the rotating rotor affected by Jayro effect was reduced to 24th by modal decomposition using Schur decomposition to reduce a reduction error. The numerical results showed that unbalance response of rotor was 53 and 80E-6 m (peak to peak), respectively, well below the allowable limits both at the rated and critical speeds.