Magnetic bearing control using fuzzy logic

Presented in this paper is a fuzzy logic approach to improve the performance of a magnetic bearing control system. Classical, linear design techniques are most often used to control the natural instability of these bearings, but magnetic nonlinearities limit control effectiveness and the region of stable performance. Therefore, the idea here is to adjust the linear controller signal in such a way that nonlinear effects are better compensated. The relationships of attractive force to the electromagnet currents and air gap are described and compensated using fuzzy principles, rather than a precise model-based control approach. Computer simulations are used to confirm that a fuzzy description of nonlinear compensation does indeed improve system performance, without requiring an exact model of the bearing nonlinearities.