Patent ID: 6316894
Filing Date: 2001-11-13
Classification: H02P

Abstract:
A three-phase brushless motor driving device for supplying a three-phase brushless motor with three-phase drive currents that differ in phase by 120 degrees from one another,wherein passage control means is provided that compares back electromotive forces appearing in three coils provided one for each phase in the three-phase brushless motor individually with a common-terminal voltage of the three coils and includes gate circuits that mask the comparison outputs individually in such a way that each of the comparison outputs is, in a predetermined short period including a level-shift point thereof, permitted to pass through the gate circuit intact when the gate circuit receives two control signals that are high from a control section of the passage control means and is, in a period between one such predetermined period and a next such predetermined period, kept at a level at which it is set after the level-shift point, andwherein the drive currents are produced by current supply means in accordance with signals resulting from passage control.