Patent ID: 6995538
Filing Date: 2006-02-07
Classification: H02P

Abstract:
1. A rotational direction detecting apparatus for a three-phase brushless DC motor, comprising: current sensors for detecting current values flowing across two of three-phase windings of the three-phase brushless DC motor, comparing means for comparing two current values detected by said current sensors, rotational angle detecting means for outputting a signal representing a rotational angle of said three-phase brushless DC motor, timing judging means for identifying an optimum latch timing based on said rotational angle detected by said rotational angle detecting means, said optimum latch timing being designated beforehand as assuring that a compared result produced from said comparing means reflects a correct rotational direction of said three-phase brushless DC motor, and latch means for inputting said compared result from said comparing means at said designated optimum latch timing identified by said timing judging means, and said latch means retaining the compared result as representing a rotational direction of said three-phase brushless DC motor until the next optimum latch timing inputted.