Analysis of saturation-induced saliencies in PM synchronous motors

Position estimation in Permanent Magnet Synchronous Motors can be performed by evaluating the magnetic saliencies. In synchronous motors with surface mounted magnets the magnetic saliencies are present due to the saturation that the rotor flux produces in the stator. A model of these saliencies is proposed, based in a simple Magnetic Equivalent Circuit and considering the zero sequence components. The usual way to evaluate the saliencies is to inject an exploring voltage signal in the non-zero sequence components (i.e. αβ or dq components). Based on the model and experimental results, it will be shown that a higher position-dependent signal can be obtained by injecting the carrier in the zero sequence.