Position dectector circuit for an electric motor

摘要

A motor control circuit for a d.c. commutator-type motor (10) includes a semi-conductor driver circuit (12) with a current sensor (12c) which provides an output voltage signal representing the instantaneous current in the motor. A detector circuit (14) analyses the output signal of the sensor (12c) to provide pulses indicating the motor shaft position. The detector circuit (14) includes a level-shifting, scaling and filtering circuit which substantially removes frequency components below a predetermined level and a pulse generator driven by the level shifting, scaling and filtering circuit. <IMAGE>