A prototype of a levitation-type PM motor with a millimeter-sized rotor

This paper describes a prototype of a levitation type PM (permanent magnet) motor with a millimeter-sized cylindrical rotor. The PM motor consists of a rotor (/spl phi/ 2.0 mm/spl times/10 mm), a pair of electromagnets, a pair of photodiodes, and an analog PD controller. The rotor successfully rotates levitating in the center of electromagnets. In this paper, driving characteristics such as rotation speed, acceleration characteristics, and magnetic friction of the rotor are discussed. It is shown that the levitation-type PM motor is very promising.