Patent ID: 6759827
Filing Date: 2004-07-06
Classification: H02P

Abstract:
A control circuit of a brush-less motor comprising:a rotor having magnetic poles; a plurality of motor windings including plural driving windings used for driving the rotor and a non-driving winding not used for driving the rotor, the non-driving winding comprising a fixed one of the motor windings; rotor rotating means for rotating the rotor by making a current flow to the plural driving windings; voltage acquiring means for acquiring a voltage induced in the non-driving winding in response to rotational movement of the rotor; magnetic pole position acquiring means for acquiring magnetic pole positions of the magnetic poles from the voltage acquired by the voltage acquiring means; current switching means for switching the current such that a direction of a magnetic field produced by the driving windings is changed in accordance with the magnetic pole positions acquired by the magnetic pole position acquiring means; and a motor drive system having a PLL circuit for generating a motor drive pulse when a rotational speed of the rotor exceeds a predetermined value.