Permanent Magnet Biased Hybrid Magnetic Bearing

Compared with conventional mechanical bearings, the magnetic bearingshave great advantages. To reduce the losses further more, the permanent magnetbiased hybrid-type magnetic bearings have been widely attached importance to.Under the aegis of important project presided by Beihang University, aiming at thehybrid magnetic bearing which is used to satellite attitude control/energy storageflywheel with angular moment of 15Nms at speed of 25000 rpm, the profoundanalysis and study on a hybrid-type magnetic bearing with permanent magnet inrotor is completed in this thesis. The main contents are as follows:(1) The configuration and operation principle of the new magnetic bearing areintroduced firstly. Based on this, the equivalent magnetic circuit models areput forward, and the models are analyzed and calculated by superpositionprinciple. The formulas of carrying forces of the magnetic bearing arededuced, and then the coupling character and current-stiffness anddisplacement-stiffness of the magnetic bearing are studied and analyzed.(2) The 2-D FEM and 3-D FEM analyses of the magnetic bearing are analyzed and calculated. To hence calculation precision, the leakage should be considered, and the leakage coefficients of permanent field and excited one are calculated separately by 2-D FEM of the magnetic bearing. The 3-D FEM of the magnetic bearing is studied to validate the validity of calculation of magnetic circuits, which analyze the distribution and action of magnetic fields under different conditions. And then the distributions of radial air-gap flux density and the force-current linear control characteristics are given. On the basis of analysis with FEM, the losses and the force-current linear control characteristics of different magnetic bearings are compared and analyzed.(3) Based on the magnetic circuit models and FEM analyses, the analysis and design software of the magnetic bearing is worked out. The electromagnetic parameters and calculation formulas under different states are defined usingthe design theory of electric machine. The program of electromagnetic design of the magnetic bearing is compiled considering leakage coefficients. The method of the transfer of ANSYS and MATLAB by VB to realize visual calculation of electromagnetic field is provided. It works in synchronous mode and plots in MATLAB with the data from the analysis of the magnetic bearing.(4) A prototype hybrid magnetic bearing is manufactured in the application of 15Nms satellite attitude control and energy storage flywheel system which can operate stably up to 25000r/min. The compared experiments are carried out between the flywheel system suspended by the prototype hybrid magnetic bearing and suspended by the active one.