Research On Rotor System Supported Bymulti-magnetic Bearings

Modern rotating machine is moving in the direction of high-speed, heavy haul, thin development. Rotor system supported by multi bearings is widely used in the fields such as steam turbines, helicopters, but the rare rotor system supported by multi magnetic bearings.Due to the misalignment of the support position, there would be a great change of the bearing load in the system that a rotor is supported by multi-magnetic bearings. After the discretization of the rotor, elevation sensitivity matrix is got under different supporting condition using transfer matrix method in this paper. The supporting loads and the rotor moments are compared between the two conditions that the supporting loads are the same and the moments of the supporting position are zero. Besides, the change of the elevation sensitivity matrix is analyzed when the bearings are assembled equidistantly and not equidistantly, and the experiment table is designed. The method of solving the elevation sensitivity matrix is confirmed in the experiment.The dynamic of the rotor is researched using transfer matrix method such as the critical speed and the unbalance response, and the magnetic bearing is equaled as the supporting stiffness. The result is compared with the finite element method. It shows that when the rotor speed is far from its critical speed, more bearings could lead to less unbalance response, and it is confirmed in the experiment.Due to the error of the manufacturing and the assembly, there would be a small misalignment among the bearings. This paper proposes that changing the suspending position to decrease the supporting load, and establishes the state equation. The control simulation is done in the Simulink module of matlab. The result shows that it can improve the ability of resisting turbulence of the system, and the maximum speed of the rotor is faster.