Development of small bearing-less motor with contact-less power supply

Abstract

A new type of small bearing-less motor was developed. The feature of this bearing-less motor is that it is composed of only electromagnets without using permanent magnets. The rotor has a structure in which the generated magnetic forces of adjacent teeth are in opposite directions and the diagonal teeth are excited in the same direction so that the amount of magnetic force is balanced. Power is supplied to the rotor by a resonant contactless power supply mechanism that uses a bridge rectifier circuit, a coil, and a capacitor. The power receiving part of the contactless power transfer mechanism is installed in the center of the rotor, and the power transmitting part is installed directly under the power receiving part. As for the levitating method, the teeth of the rotor are attracted to the teeth of the stator, and the rotor is levitated while suspended. Rotation controlled by applying 3-phase AC to the stator, but not in the height direction. The rotation method uses the difference in the number of teeth between the stator and the rotor and controls the rotation by adjusting the current in the stator coil. In the previous studies, we calculated the rotating torque and the levitation force of the designed mechanism using electromagnetic field analysis software to miniaturize the non-contact power feeding mechanism. In this paper, we confirmed the maximum levitation position and the controllability in the horizontal and tilt directions using electromagnetic field analysis software and explained the prototype and the control system.