Patent ID: 6741049
Filing Date: 2004-05-25
Classification: H02P,Y10S

Abstract:
A circuit arrangement for driving at low voltage a brushless dc motor having a rotor and at least two windings for driving one or more permanent magnets on the rotor, the arrangement comprising:drive circuits configured to provide drive signals to the windings; one or more sensors arranged to determine the rotational position of the rotor; an analogue processing circuit configured to process signals received from the one or more sensors so as to provide a feedback signal; a regulation circuit configured to extract energy from inductive voltages produced by the windings and to generate a voltage power source for the processing circuit; an oscillator circuit configured to provide a pulse signal; and a control circuit configured to receive the feedback signal and the pulse signal, the control circuit being further configured to control the drive circuits such that: in a first mode of operation, when the rotor is turning, the drive circuits are selectively enabled based on the feedback signal; and in a second mode of operation, when the rotor is not turning, the drive circuits are pulsed based on the pulse signal so as to generate inductive voltages in the windings.