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). Analysis 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.