BRUSHLESS DC MOTOR WITHOUT A ROTOR POSITION SENSOR

摘要

A full wave drive brushless DC motor system detects zero-crossing points of counter electromotive forces respectivelyinduced by the stator windings, and then pulse-shapes the thusdetected zero-crossing points to obtain a pulse signal train, andthen measures the period of the thus obtained pulse signal trainto determine a conducting phase of the stator windings inresponse to the thus counted period. The system is therebycapable of supplying an electric current bidirectionally to eachof the stator windings without using a position sensor fordetecting a position of a rotor.