Abstract: A method and apparatus for electronic control of a direct current motor is disclosed based upon a sensorless commutation technique using voltage vector analysis. A voltage vector is produced by addition of supply phase voltage vectors of energized windings with the back-electromotive force vector of the unenergized winding. The resultant voltage vector rotates at the same speed as the rotor and possesses rotor position information used to commutate phase windings. The angle that the resultant voltage vector makes with the real axis is measured to commutate the phase windings. By parking the rotor in a predetermined position, this technique can be used to efficiently start the motor from rest and commutate phase windings during normal operation.

Abstract: A method and apparatus for electronic control of a direct current motor is disclosed based upon a sensorless commutation technique using voltage vector analysis. A voltage vector is produced by addition of supply phase voltage vectors of energized windings with the back-electromotive force vector of the unenergized winding. The resultant voltage vector rotates at the same speed as the rotor and possesses rotor position information used to commutate phase windings. The angle that the resultant voltage vector makes with the real axis is measured to commutate the phase windings. By parking the rotor in a predetermined position, this technique can be used to efficiently start the motor from rest and commutate phase windings during normal operation.

Abstract: A method and an apparatus for determining rotor position information of a Brushless DC motor using the resultant voltage vector produced by addition of phase voltage vectors of the energised windings and the BEMF vector of the unenergised winding. This resultant voltage vector called the BEMF Space Vector rotates at same speed as the rotor and possesses rotor position information used to commutate phase windings. Phase voltage vectors for the computation of the BEMF Space Vector are obtained by referring scalar phase voltages in the electrical circuits to the magnetic axes of the magnetic circuits, since scalar and vector current magnitudes are equal. Angles that the BEMF Space Vector makes with the real axis are measured to commutate the phase windings. This technique is referred to as the De Four BEMF Space Vector Resolver, used to efficiently start the motor from rest and commutate phase windings during normal operation.