N 92 - 27739 Low Power Magnetic Bearing Design For High Speed Rotating Machinery

317 SUMMARY Magnetic suspension technology has advanced to the point of being able to offer a number of advantages to a variety of applications in the rotating machinery and aerospace fields. One strong advantage of magnetic bearings over conventional bearings is the decrease in power consumption. The use of permanent magnets, along with electromagnets, is one appealing option which can further reduce the power consumption of the bearing. The design and construction of a set of permanent magnet biased, actively controlled magnetic bearings for a flexible rotor is presented. Both permanent magnets and electromagnets are used in a configuration which effectively provides the necessary fluxes in the appropriate air gaps, while simultaneously keeping the undesirable destabilizing forces to a minimum. The design includes two radial bearings and a thrust bearing. The theoretical development behind the design is briefly discussed. Experimental performance results for a set of operating prototype bearings is presented. The results include measurements of load capacity, bearing stiffness and damping and the dynamic response of the rotor. With few exceptions, the experimental measurements matched very well with the predicted performance. The power consumption of these bearings was found to be significantly reduced from that for a comparable set of all electromagnetic bearings.