**5. Conclusions**

A magnetic top levitates by itself, without any active control system, so long as it rotates in a certain speed range. The authors propose a simple and intuitive analysing method to predict characteristics of the magnetic top.

The quasi-three-dimensional static analysis, considering shapes and layout of the ringshaped rotor and stator magnets, is used to explain the principle of levitation and obtain the preliminary design parameters of the rotor and stator magnets. The behaviour of the magnetic top is also investigated by dynamic simulations based on the three-dimensional equations of motion considering the moment of inertia for the rotating magnetic top. The following results are obtained:


A magnetic top may be used as a rotating demonstration model in which some swaying motion can be permitted such as in toys or other relaxation items. When a magnetic top is used in commercial system, a rotor should be rotated by some non-contact drive mechanism such as electric motor or air turbine, etc. Furthermore, touch down bearing should be equipped to suspend a rotor while rotating speed is out of operating range. Fundamental requirements to design a magnetic bearing based on the principle of a magnetic top will be rotor weight and rotation speed. A rotor shaft should be designed considering mechanical requirements such as torque.

In the experimantal model, because ferrite magnets are used for the rotor and stator magnets, the restoring forces are very small for commercial applications. However, if rare earth permanent magnets and rigid suspension devices are used, sufficient restoring forces may be expected to be generated for use as a commercial passive magnetic bearing.
