A permanent-magnet rotor containing an electrical winding to improve detection of rotor angular position

Sensorless detection of rotor angular position is desirable for decreasing the cost and increasing the reliability of permanent magnet AC motor drive systems. This paper describes tests performed on a rotor that has surface-mounted magnets and a conducting winding that links only the d axis of the rotor. The rotor winding increases the variation of the stator winding inductance that occurs as the rotor rotates and improves the accuracy of rotor angular position estimates.