Method and apparatus for detecting velocity profiles of a spinning rotor of a polyphase DC motor

摘要

A circuit and method for operating a polyphase dc motor of the type having a plurality of driving coils that are commutatively energized in a predetermined sequence to rotate a rotor has a zero crossing detector connected to determine when a back emf of a floating driving coil crosses zero. A generator for generating commutation sequence signals controls which of said driving coils are energized a delayed time after said zero crossing detector detects that a back emf of a floating driving coil has crossed zero. A mask circuit inhibits said zero crossing detector for a delayed time after a commutation change, in dependence upon an acceleration of the rotor. Also, a circuit is provided for adjusting the commutation delay time after a back emf of a floating one of said coils crosses zero, in dependence upon the acceleration of the rotor.