Centrifugal cold compressors, now being developed at Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, are used to pump gaseous helium from saturated liquid helium tank to obtain super-fluid helium in cryogenic refrigeration systems. Active magnetic bearings (AMB) are replacing traditional oil-fed bearings as the optimal supporting assembly for cold compressors because of their many advantages. In this paper, five degrees of freedom AMBs are developed for the centrifugal cold compressor application. Considering the rotational speed is high, causing the nominal plant model to deviate materially from the precise mathematical model, robust Hco control methods are proposed to control AMB systems. Experimental results show that Hco controllers guarantee good dynamic and steady state performance in the closed-loop system at the rotation speed of 50 000 rpm.
展开▼
