Patent ID: 6995530
Filing Date: 2006-02-07
Classification: H02P

Abstract:
1. A method for starting a brushless direct current motor, comprising: simultaneously applying commutation pulses to at least two phase coils to induce a rotor to rotate to a starting position and then de-energizing the at least two phase coils; simultaneously applying commutation pulses to at least two phase coils to induce the rotor to rotate from the starting position in a predetermined direction; de-energizing all phase coils for a first time interval after the rotor is rotating and sampling a back EMF signal in at least one of the phase coils to determine a first value indicative of an electrical period of the back EMF signal or a portion of an electrical period of the back EMF signal; and, applying commutation pulses to at least two phase coils for a second time interval, the second time interval being based on the first value.