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Bekinal S.I.,Gogte Institute of Technology ogy | Anil T.R.,Gogte Institute of Technology ogy | Jana S.,National Aerospace Laboratories, Bangalore
Progress In Electromagnetics Research B | Year: 2012

The use of permanent magnets as bearings has gained attention of researchers nowadays. The characteristics of forces and moments have to be analysed thoroughly for the proper design of permanent magnet bearings. This paper presents a mathematical model of an axially magnetized permanent magnet bearing (ring magnets) using Coulombian model and a vector approach to estimate the force, moment and stiffness. A MATLAB code is developed for evaluating the parameters for five degrees of freedom (three translational and two rotational) of the rotor. Furthermore, it is extended to analyse stacked ring magnets with alternate axial polarizations. The proposed model is validated with the available literature. Comparison of force and stiffness results of the presented model with the results of three dimensional (3D) finite element analysis using ANSYS shows good agreement. Finally, the cross coupled stiffness values in addition to the principal stiffness values are presented for elementary structures and also for stacked structures with three ring permanent magnets.


Bekinal S.I.,Gogte Institute of Technology ogy | Anil T.R.,Gogte Institute of Technology ogy | Jana S.,National Aerospace Laboratories, Bangalore | Kulkarni S.S.,National Aerospace Laboratories, Bangalore | And 3 more authors.
Progress In Electromagnetics Research B | Year: 2013

This paper presents the design and analysis of permanent magnet (PM) thrust bearing made up of three ring pairs for five degrees of freedom of the inner rings (rotor rings). The arrangement pattern of rings in PM bearing is considered in two ways: conventional structure and Halbach structure. The simplified three dimensional (3D) mathematical models employing Coulombian approach and vector method are used to design the bearing. MATLAB codes are written to evaluate the axial force, stiffness and moments in both the structures for five degrees of freedom, thereby the effect of axial, radial and angular displacements of the rotor on the aforementioned characteristics is addressed. The results of the mathematical model are validated by the results of 3D Finite Element Analysis (FEA) and experiments. It is observed that, the conventional structure seems to be more sensitive to the angular displacement, as the percentage decrease in force and stiffness is more with respect to angular displacement than the Halbach structure. The effect of angular displacement of the rotor on the performance of bearing in both the structures is crucial.

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