Analysis of Cross Feedback Control for the Magnetically Suspended Flywheel Rotor

For the magnetically suspended flywheel rotor of big moment of inertia, gyro effect is significant when it is rotating at high speed. Traditional decentralized PD control cannot insure the stability of the system. This paper mainly studies the cross feedback control, analyzes the velocity and displacement cross feedback, explains the control principle of cross feedback. The poles of precession and nutation, and the damping curves are given, showing the trends. And the results of the simulation experiments show that the cross feedback control is effective to restrain the gyro effect. Flywheel systems are widely used in the energy storage, uninterruptible power supply, satellite attitude control, adopting magnetically suspending is an important developing way for the flywheel systems. Magnetic bearing is a new kind of electromagnetic bearing using magnetic force to balance the rotor between the stator. Magnetically suspended machines have the unique advantages of contact-free, without lubrication, adjustable stiffness and damping that traditional bearing cannot substitute. Magnetically suspended flywheel systems are stable in theory adopting decentralized PD control. However, for the flywheel rotor of big moment of inertia, gyro effect is significant when rotating at high speed, constrains to raise the rotating speed, the stability is deteriorated, new control strategy is needed to restrain the gyro effect. This paper mainly studies the cross feedback control aimed at the gyro effect. The control principle of velocity and displacement cross feedback are introduced, analyzed the poles, frequencies and damping of precession and nutation, and the results of simulation experiments are given.