Analysis on Response of Magnetic Bearing System to External Forces Comparison between Optimal Regulator System and Independently Controlled System

Analysis on Response of Magnetic Bearing System to External Forces Comparison between Optimal Regulator System and Independently Controlled System Takeshi MIZUNO, Toshiro HIGUCHI and Noboru AIKAWA One of the significant problems in designing a magnetic bearing control system is that there are gyroscopic couplings between two rotational motions of the suspended rotor. Because of these couplings the optimal regulator system related to the rotational motions needs antisymmetric cross feedback compensation in addition to usual displacement and velocity feedbacks of individual motion. It has been shown that the optimal regulator system has better transient response characteristics than the independently controlled system, that is to say, the system with no cross feedback compensation which is obtained as a result of disregard of gyroscopic effects in the process of designing the control system. In view of applications of magnetic bearings it is important to investigate the dynamic behaviour of the system disturbed by external forces besides the transient natural motion. This paper shows an analytical method to study forced motions of the gyroscopic coupled systems when static or sinusoidal varying forces are applied to the rotor and clarifies differences between the optimal regulator system and the independently controlled system. Experimental tests are carried out to verify the theoretical results.