Tracking rotation of direct current motors used in motor vehicle for ventilation or heating, has detector sensing oscillation of impedance of motor due to commutations of connecting brushes

摘要

The rotation tracking for a direct current motor (M) has a detector sensing oscillation of the impedance of the motor due to the commutations of the connecting brushes, together with a counter to count the oscillations. The oscillations are detected by a differential amplifier (1) whose output is converted (2) to pulses, which can be counted to track the movement of the motor.