BRUSHLESS DC MOTOR HAVING ELECTRONIC COMMUTATION RESPONSIVE TO ROTOR POSITION AND INDUCED ARMATURE WINDING VOLTAGE

摘要

A single sensor brushless DC motor contains two windings that are alternately energized to sustain rotor rotation and includes transistor switches in series with each motor winding. The transistor in series with the first winding is driven directly from the sensor so as to energize the first winding when the sensor is illuminated and that transistor is driven into saturation. The transistor in series with the second winding has an input terminal coupled to the first motor winding so as to react to voltages induced in the first winding during times when the first winding is de-energized.