Electronically commutated motor with correction of sensed rotation-direction signal

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 (Tp), 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 driving said semiconductor switches, between commutation events, by applying a substantially constant aggregate level of current, thereby facilitating quiet operation of said motor.

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;
• a phase shifter having inputs coupled to said winding phases, and furnishing differentiated output signals derived therefrom;
• and
• a filter coupled to outputs of said phase shifter and furnishing filtered output signals to a comparator in said microcontroller, said microcontroller processing said filtered output signals to generate control signals for application to said semiconductor switches.