Determination of the position of the shaft of an electric motor, senses e.m.f. generated in operating relay coils and motor winding passes to generate signal that is processed to determine rotor position and speed

摘要

The brush-type DC motor is controlled by relays (20,22), and uses coupling between the motor windings and the relay windings to determine position and speed of the motor. The electromotive force generated in the relay windings is filtered (30) to remove the DC component, amplified (32) then compared (34) to a reference potential to detect passage of a motor winding in front of a relay winding.