Abstract: Through the study of gyroscopic dynamics of a flywheel rotor system supported by active magnetic bearings, and the analysis of the influences of magnetic forces to the nu-tation and the precession of the rotor, the effects of the magnetic forces to the rotor are divided into four basic supporting com-ponents. Their different influences to the stability of the nuta-tion and the precession are discussed respectively. The propor-tion of the four components can be adjusted by a controller to change the damping characters of the nutation and the preces-sion, and achieve a high speed operation. Based on the study, the principles of controller designs for flywheel systems sup-ported by active magnetic bearings are summarized, and they provide a direction for designing effective controllers for the systems at high rotation speeds.

Key words: Active magnetic bearing, Control principles, Flywheel, Gyroscopic dynamics