Patent ID: 7956561
Filing Date: 2011-06-07
Classification: H02P

Abstract:
1. A rotor position detecting circuit for detecting the rotor position of a brushless DC motor having a plurality of phase coils, the rotor position detecting circuit comprising: first means for detecting phase voltage induced in one of the phase coils; a first position detecting circuit including a low-pass filter connected to the means for detecting voltage and a first comparator that compares the output voltage of the low-pass filter with a threshold level to form a first rotor position signal; and a second position detecting circuit including a second comparator that compares the phase voltage with a threshold voltage and second means for digitally processing the output voltage of the second comparator to form a second rotor position signal; and third means for correcting the first rotor position signal by the second rotor position signal to provide a final rotor position when the rotation speed of the brushless DC motor is in a measurable range.