An Observer-based Robust Stabilization of 3-axes Controlled Type Magnetic Bearings Using a Digital Signal Processor

Abstract

This paper deals with an effective stabilization of 3-axes controlled type magnetic bearings. All the five degrees of freedom of the motion for the suspended rotor are stabilized completely by using only three pairs of electromagnets with permanent magnets. We employ a minimal-order observer in order to estimate the motion of the rotor which can not be measured by the position sensors. First, the state-space equation of the magnetic bearing is derived on the assu mption that t he rotor is rigid and well-balanced. Next, an observer-based discrete-time control system is designed. In particular, we make use of an attractive design method: the turn-over method, to place all the closed-loop poles in a desirable stability region. Moreover, the robust stability of the system is investigated against the perturbations caused by the rotation of the rotor. Then, a digital signal processor-based controller is actually implemented. Finally, several experimental results show that the designed control system achieves excellent stability and good performance.