Patent ID: 6538403
Filing Date: 2003-03-25
Classification: H02K,H02P

Abstract:
A method for controlling a brushless DC motor including a rotor and a stator having at least three phases, the rotor being magnetically coupled to and moveable by the stator when the phases are appropriately energized, each of the phases being characterized by a corresponding voltage waveform, comprising the steps of:providing no more than two position sensors for sensing a rotor position during a start-up mode, each position sensor having an associated position sensor signal; aligning the position sensors to sense the rotor position such that each position sensor signal indicates a zero torque point corresponding to a phase voltage waveform; sensing the position of the rotor such that the position sensor signals indicate a start-up operating state; during a first ambiguous start-up state: alternately energizing two predetermined phases; and during a defined start-up operating state: energizing one predetermined phase.