Abstract
A simple and stable flywheel system with high temperature superconducting levitation is presented, in which a control is not needed for levitation. In order to have stable levitation, a superconductor and a permanent magnet are used, and three permanent magnets support the top of the shaft. In the part of drive system, eight-poles cylindrical permanent magnet and eight cylindrical coils are used to drive the rotor. Vibration force due to the driving is zero in this system. A coil-type electromagnetic damper is presented which works in the magnetic field of levitation permanent magnet. It consists of four coils. Using this system, a control like the sensorless control can be performed by using sensors consisting of coils only. Analytical expressions are obtained for both torques for our cylindrical type motor and vibrations of the shaft. Experimental tests have been carried out. It is clarified that our system has stable levitation, and vibrations are extremely suppressed.
