Analysis and Testing of Magnetic Bearing with Permanent Magnets for Bias

Active magnetic bearings constructed with electromagnets only are usually bulky and power-consuming. This shortcoming can be remedied by adopting permanent magnets as the source of bias flux. Satisfactory results achieved by using rare-earth permanent magnets substantiate the feasibility of using permanent magnet bias in magnetic bearings. In this paper, an analytic model for permanent-magnet-biased magnetic bearings is presented. The static characteristics of a prototype are tested and compared with values estimated using this model. Manufacturing the prototype and subsequent testing offer some technological information which is important for future improvements.