Control apparatus for brushless motor

摘要

A control apparatus detects a suitable starting point during rotational oscillation of a rotor at the start of a brushless motor by combining the polarity of a counter electromotive force generated in an armature coil of an armature winding of the brushless motor for a nonexcited phase due to the rotational oscillation of the rotor (when armature coils for particular phases are excited at the start of the brushless motor) with the pulse edge of an excitation switchover signal obtained from the potential of a neutral point of the armature winding having the armature coils connected in star-connection and that of a neutral point of a detecting resistance circuit having resistors connected in star-connection. Each of the resistors of the resistance circuit is arranged in parallel with a corresponding one of the armature coils the armature winding. By driving the brushless motor from the detected suitable starting point, it is possible to effect smooth and quick control of the starting operation of the brushless motor.