Method and apparatus for controlling a brushless DC motor that indicates a motor failure

A method for controlling a brushless DC motor having a permanent magnet rotor, a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, a comparison circuit for each of the phases of the stator winding for comparing a specified reference voltage with stator winding terminal voltages and for outputting specific response patterns, and a position detection circuit for detecting a rotor position based on the outputs of the comparison circuits, the method comprising:

• receiving a particular specific response pattern output from the comparison circuits when the comparison circuits are coupled to conducting phases of the stator winding;
• comparing the particular specific response pattern output from the comparison circuits to a particular normal response pattern of the comparison circuits when the comparison circuits are coupled to the conducting phases of the stator winding;
• and
• detecting abnormalities based on a difference between the particular specific response pattern and the particular normal response pattern.

A method for controlling a brushless DC motor having a permanent magnet rotor, a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, a plurality of switching means for selectively providing current patterns to each phase of the stator winding, a comparison circuit for each of the phases of the stator winding for comparing a specified reference voltage with stator winding terminal voltages, and a position detection circuit for detecting a rotor position based on the outputs of the comparison circuits, the method comprising:

• storing normal response patterns of the comparison circuits;
• generating specific response patterns in response to the current patterns provided by the plurality of switching means;
• and
• detecting abnormalities by comparing the specific response patterns output from the comparison circuits when the comparison circuits are coupled to conducting phases of the stator winding to the normal response patterns of the comparison circuits the comparison circuits are coupled to the conducting phases of the stator winding, wherein a difference between a particular specific response pattern and a particular normal response pattern indicates a type of abnormality in the DC motor.