SIMPLE BRUSHLESS DC FAN MOTOR WITH REVERSING FIELD

摘要

A simplified fan and brushless DC motor employs an annular permanent magnet magnetized in segments about its circumference. Each segment is oppositely radially magnetized with respect to its adjacent segments. Fan blades are located within the annular magnet. A coil comprising two electrically independent and bifilar wound windings, connected to be oppositely energized, and an electromagnet structure defining two pole pieces reside outside the permanent magnet annulus. A Hall effect device alternately energizes the separate coil windings in response to passage of the segments of the rotor magnet to alternately produce opposite magnetic fields in the pole pieces. Thus commutated, the double coil arrangement affects rotation of the rotor and the fan blades.