Single or three=phase machine without commutator or slip-rings - has external rotor whose centrifugal expansion reduces air-gap induction, keeping output voltage constant

摘要

The machine delivers constant voltage in spite of variations in its speed. It has a permanent magnet external rotor. The size o the rotor is chosen so that the expansion of the rotor due to centrifugal forces produces within a specified range of speeds such an increase of air-gap between the stator and the inside of the rotor that the reduction in the air-gap induction compensates the increase in speed. The stator fits in a hole in the centre of the rotor.