Study On The Operating Characteristic Of Permanent Magnetic Bearing

Permanent Magnetic Bearing(PMB) has a series of fine qualities, such as small fiction, no wear, no lubrication, no seal, low consumption, no pollution, high velocity, high-accuracy, long-life, high reliability and so on, which highly meet the requirements of energy conservation, environment protection and low carbon economy advocated by modern society. However, PMB also has the defect that the rotor can't achieve steadily suspension with the support of PMBs alone. The rotor can suspend steadily only if the other kind of restrain added at least at one DOF. Nowadays the common method making the rotor suspend completely is combining the PMB and mechanical bearing, AMB or SMB as a bearing system.Domestic and overseas scholars have done lots of jobs about the study of PMB, and gain a lot of results. However we can see from the papers published that single PMB is studied frequently but the studies on PMB in bearing system are a few. Besides, the theoretical analysis has done many, but experimental study, especially dynamic experimental study on PMB has been done little. In view of the above questions, the following jobs are done:First, when the axis supported by a radial PMB and a mechanical bearing is applied by a radial load, the characteristic of motion of the inner ring of the radial PMB has been analyzed. The main methods of magnetic analysis of PMB have been introduced. And the formulas of the magnetic force of the radial PMB in deflection model have been deduced with the method of Equivalent magnetic charge method, and achieve that it is very complex that calculate the magnetic force of radial PMB in deflection model by Equivalent magnetic charge method.Second, the magnetic forces of radial PMB of deflection model are analyzed by the finite element method, and gain the following characteristics:1)both the radial and the axial magnetic force will increase with the increase of deflection angle,2)the radial magnetic force will be overrated and the axial magnetic force will be underrated in the deflection model compared with in the radial shift model,3) the radial magnetic force of PMB in the deflection model will increase with the decrease of the air gap or the increase of the thickness of magnetic rings and the axial magnetic force will increase with the decrease of the air gap, but the thickness of magnetic rings do not affect the axial magnetic force much.Third, the experimental platform of the dynamic characteristics of PMB is designed. The platform is not only easy to install and the PMB composed of one to four pairs of permanent magnet ring can be tested on it by changing a few of parts. The test content includes the radial and axial force and stiffness in static, and the force and stiffness in dynamic. The principle, over-all structure and main parts are designed and analyzed. Last, force analysis is done on the axis of the platform when the radial magnetic force is being tested and the static simulation analysis and model analysis are done on the axis in order to check its strength, stiffness and natural frequency.