Brushless electromotor for servo system - has low rotating mass with disc rotor and multipole stator for improved speed control

摘要

A shaded pole motor with a split stator and disc rotor has a large number of between 20 and 80 poles (2) in each stator half. A basket weave type winding (1) is incorporated in each half stator. During assembly the half stators are placed such that the pole gap in one half coincides with the centre of the pole in the other half. The AC supply to one stator half is displaced by 90 deg. Speed variation is achieved via frequency control or by changing the phase angle difference between the stator supplies. The rotor disc is made of non-ferrous material and thus transparent to the magnetic flux circuits which are formed and closed between the stator poles. Rotation occurs due to the generation of Foucault current in the disc reacting against the flux lines.