CONTROL OF A BRUSHLESS MOTOR

摘要

A method and apparatus for controlling a brushless motor having a plurality of windings switched through a sequence of steps includes determining a transition time from one step to the next. The transition time is determined by detecting a zero crossing of a back emf in one of the plurality of windings. A delayed time to be added to the transition time is determined wherein the delayed time is selected according to the step in the sequence of steps being executed and is dependent on the duration of one of a preceding interval between zero crossings. A delay time proportional to a duration of a last shortest interval is supplied to follow a longest interval. A delay time proportional to a duration of a last longest interval is supplied to follow a shortest interval and a delay time proportional to a duration of a medium interval is supplied to follow a medium interval. The method may be used, for example, with a star or delta connected motor having any number of windings.