Active magnetic bearing design study

The purpose of this paper is to propose a useful method to implement active magnetic bearings (AMBs) on an existingrotating shaft which rotates on conventional bearings. This is feasible if AMBs can produce the same reaction loads ofconventional ones and if the size of vane is large enough to host an AMB. As this substitution could offer some difficultiesdue to the different size between magnetic bearings and conventional ones, a set of equations are performed to showthat a variation of some parameters can solve this problem. The journal ratio is the geometrical parameter introduced todevelop the present analysis. The variation of journal ratio does not produce a variation of the pole’s surface so that thereaction load does not change. The results are analyzed by numerical analysis by mathematical relationships involving thedesign parameters, magneto-static simulations and dynamic simulation on shaft when it is tested by disturbance rejectionand reference tracking input in order to analyze the differences on dynamic behavior of the shaft on its suspendedsections. Results show that the displacement pattern of the suspended sections remains unchanged, confirming that thereaction load, produced by pole expansion, remains the same varying the journal ratio.