Patent ID: 6577085
Filing Date: 2003-06-10
Classification: H02P

Abstract:
A self-commutated type method of control of a brushless motor having a plurality of windings switched according to a determined cycle of steps, in which each transition between steps is determined at a time following a zero crossing of a back emf by a determined delay, wherein the delay is chosen selectively according to the step involved by selecting an interval from a plurality of preceding intervals between zero crossings depending on a duration of the interval and by determining the delay based on the duration of the selected interval;further including the steps of: determining for a motor rotating at a constant speed the duration of the intervals between zero crossings of the back emf; providing a delay proportional to the duration of a last shortest interval following a longest interval; providing a delay proportional to the duration of a last longest interval following a shortest interval; and providing a delay proportional to the duration of a last interval of medium duration following an interval of medium duration.