Patent ID: 8415908

Claim:
A driving apparatus for a brushless motor having a plurality of motor windings, the apparatus comprising: a plurality of switch half-bridges coupled to a power line and configured to be coupled to the plurality of motor windings; a memory configured to contain a plurality of signal profiles to be cyclically applied to the plurality of motor windings; a multiplier configured to multiply values of the signal profiles from said memory by a scale factor; a control circuit configured to generate PWM signals for switches of said plurality of switch half-bridges according to values output from said multiplier; a polarity detector configured to detect a polarity of a current which passes through at least one of the motor windings; and a scale factor controller coupled to the polarity detector and configured to make each signal profile to be applied to each motor winding either higher than a back-electromotive force generated by the motor or equal to the back-electromotive force depending on the polarity detected by the polarity detector.