摘要：A magnetic bearing is a bearing which supports a load using magnetic levitation. Magnetic bearings support moving machinery without physical contact; for example, they can levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear. Magnetic bearings are in service in such industrial applications as electric power generation, petroleum refining, machine tool operation, and natural gas pipelines The evolution of active magnetic bearings may be traced through the patents issued in this field.. Earlier patents for magnetic suspensions can be found but are excluded here because they consist of assemblies of permanent magnets of problematic stability.
关键词：magnetic bearings;active magnetic bearing multi-frequency periodic vibration
