Rotor position estimation of AC machines using the zero-sequence carrier-signal voltage

This paper analyzes the sensorless control of ac machines based on the zero-sequence voltage generated by the injection of a carrier-signal voltage. The analysis focuses on rotor position estimation (tracking of rotor-position-dependent saliencies), but the methods discussed apply equally to flux position estimation (tracking of flux-dependent saliencies). Analyses of relevant aspects like selection of the carrier-signal frequency, measurement of the zero-sequence carrier-signal voltage, and decoupling of saturation-induced saliencies are included.