Patent ID: 6285149
Filing Date: 2001-09-04
Classification: H02P

Abstract:
A motor drive circuit for a three-phase motor, the motor drive circuit including a commutator arranged to provide a driving voltage to the motor from a DC voltage source, a sequencer operating the commutator to pulse width modulate the source voltage so that a motor current has a continuously variable waveform, the sequencer being responsive to an error signal to align the driving voltage with the motor current waveform, and a phase detector supplying the error signal to the sequencer comprising:a sensor providing a sense voltage representative of the motor current;a first sample circuit providing a plurality of first samples of respective instantaneous values of the sense voltage;a second sample circuit providing a second sample of a selected instantaneous value of the sense voltage; andan error generation circuit providing the error signal based on a difference between the second sample and each of the plurality of first samples.