Analysis Of Mechanical Characteristics Of Permanent Magnet Bearings

Permanent magnet bearings is one kind of magnetic bearings by using permanent magnet to levitate rotor. It is widely used in many kinds of fields with the advantages of simple, reliability, no erosion, less energy consumption. Mechanical characteristics of permanent magnet bearings is expressed by bearing capacity and bearing stiffness. Analysis of mechanical characteristics of permanent magnet bearings plays a significant role in analysis and design of permanent magnet bearings. A grasp of whole knowledge about mechanical characteristics of permanent magnet bearings is significant to improve the study of permanent magnet bearings.In many years, the analysis of mechanical characteristics of permanent magnet bearings is deeply studied by scholars in the world, mathematical model is built for analyzing mechanical characteristics of permanent magnet bearings by static magnetic circuit method and equivalent magnetic charge method. However, theory calculation and design of permanent magnet bearings is far from enough. The dissertation places an emphasis on the research of mechanical characteristics of permanent magnet bearings, research is mainly done in the following aspects:Mechanical characteristics of permanent magnet bearings is analyzed by static magnetic circuit method and equivalent magnetic charge method respectively, mathematical models are also built by the two methods.With consideration of variety of magnetic circuit in permanent magnet bearings, a new mathematical model dynamic magnetic circuit is presented, which has been widely used in the design of lifting permanent magnetic crane. The model has a simple form and less than seven parameters. It's shown that the present model is of considerableaccuracy by comparison of the computer calculation with test results. Therefore, this model may apply for a broad range of permanent magnet bearings used in mechanical characteristics.In this dissertation, permanent magnet bearings is built into finite element model for analyzing mechanical characteristics. Based on ANSYS, mechanical characteristics of permanent magnet bearings can be calculated by inputting dimensions and physical parameters on the built actual structure. Finite element model can achieve accurate calculation, providing a new analysis tool for the study of permanent magnet bearings.Test device is designed and made for the test of mechanical characteristics of permanent magnet bearings. Test results show that axial force of permanent magnet bearings is not influenced by progressive displacement or displacement decline; axial force is symmetry of origin.By the comparison and analysis of different theory calculations and test results, the evaluation of theory calculation methods for analyzing mechanical characteristics of permanent magnet bearings is made: the calculation of static magnetic circuit is simple, which owns less mathematical model parameters, but its accuracy is not high. Computational accuracy of equivalent magnetic charge method is high , but its calculation is complicated. Dynamic magnetic circuit method is good for theory analysis and numerical calculation of mechanical characteristics of permanent magnet bearings. Calculation accuracy is high while calculating process is simple, However, the mathematical model built by dynamic magnetic circuit method in this dissertation can't calculate radial force of radial permanent magnet bearings. Finite element method is an effective method for analyzing mechanical characteristics of permanent magnet bearings. However, the use of this method needs basic knowledge of finite element, calculation depends on the type of mesh element and meshing accuracy.