Patent ID: 8575874

Claim:
An electronically commutated motor comprising: a permanent-magnet rotor; a stator having a plurality of winding phases; a respective semiconductor switch controlling current flow to each stator winding phase; a microcontroller commutating said motor by controlling operation of said semiconductor switches; and means for sampling, at a plurality of times during each commutation period (T p ), a voltage signal occurring in at least one of said winding phases, and for furnishing values measured by said sampling to said microcontroller for detection of a direction of rotation of said rotor; and means for measuring a noise component in said voltage signal occurring in at least one of said winding phases, and for furnishing said noise component to said microcontroller, said microcontroller being adapted to correct said values furnished to said microcontroller, to compensate for said noise component, and to thereby improve accuracy of said detection of direction of rotation.