In a brushless motor control method and a brushless motor controller in
accordance with the present invention, a rotor rotation position detection
means detects the time of the intersection of a detected induced voltage
and an induced voltage reference value. In addition, a motor speed
calculation means calculates the rotation speed of a brushless motor on
the basis of the interval of the intersection times detected by the rotor
rotation position detection means. Furthermore, a speed control means
outputs a duty factor index on the basis of the deviation between the
command speed and the rotation speed of the brushless motor. Still
further, a switching signal generation means outputs switching signals to
groups of switching devices on the basis of the rotation speed and the
duty factor index at the time of the intersection.
