An H∞ control system design of a magnetic bearing considering periodic disturbance

This paper deals with an Hscr_infin DIA control system design of a magnetic bearing considering periodic disturbance. Hscr_infin control problem which treats a mixed disturbance and an initial state uncertainty attenuation (DIA) control is expected to provide a good transient property, and we confirmed that DIA control has a good rotational performance by some experiments. On the other hand, active magnetic bearings allow contact free suspension of rotors and they are used for various industrial purposes. We derive a mathematical model of the magnetic bearing which has complicated rotor dynamics and nonlinear magnetic property. In this paper, we propose a modified control system design of Hscr_infin DIA control in order to consider the periodic disturbance for the magnetic bearings. In fact, we get a controller taken a peak at specified frequency by adding a frequency weighting function in generalized plant. Experimental results show that the proposed robust control approach is effective for improving rotational performance