**Magnetic Bearings**

18 Will-be-set-by-IN-TECH

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Vol. 21, No. 5, 2012-2024

36, No. 5, 8862-8875

**Chapter 6** 

© 2012 Azukuzawa and Yamamoto, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Azukuzawa and Yamamoto, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

**Feasibility Study of a Passive Magnetic Bearing** 

Magnetic bearings can suspend rotating bodies without any mechanical contact. They have advantages such as being free of dust, noise, vibration and maintenance. Some magnetic bearings are already in commercial use in specific apparatuses such as high vacuum pumps or contamination free applications [1]. However, the high cost of the control apparatus for five degrees of freedom of the rotor prevents their wide application at present. It is thus

The authors have previously reported on the characteristics of the magnetic force acting between a couple of permanent magnets [2]. A magnetic top, consisting of a couple of ring-shaped permanent magnets, can be levitated without any control while maintaining rotation by itself. This fact suggests that the magnetic top may be a potential candidate for a passive magnetic suspension system. Several efforts have been made to explain the levitation mechanism of the magnetic top. San Miguel proposed noble analytical method with complex formulas showing

In this chapter, an intuitive and easy analytical method based on the equivalent coil currents

A quasi-three-dimensional analysis, in which the three-dimensional shapes and layout of the ring-shaped permanent magnets are considered to estimate the magnetic forces acting on the levitating permanent magnet, is proposed. The principle of levitation of the magnetic top and the dimensions of the permanent magnets to realise levitation are discussed using

Furthermore, simulations based on the three-dimensional equations of motion are performed to investigate the dynamic behaviour of the magnetic top. The simulated results well predict the dynamic behaviour observed in the experiments. The simulations based on

that a magnetic top can maintain levitation if it rotates with slight precession [3].

**Using the Ring Shaped Permanent Magnets** 

Teruo Azukuzawa and Shigehiro Yamamoto

Additional information is available at the end of the chapter

necessary to develop a low-cost magnetic bearing system.

model for a ring-shaped permanent magnet is proposed.

the two-dimensional equations of motion for the magnetic top.

http://dx.doi.org/10.5772/51347

**1. Introduction** 

properly cited.
