Fast and Smooth Initial Position and Magnet Polarity Estimation of Salient and Near Zero Saliency PM Synchronous Machines

A general solution for initial position and magnet polarity estimation on PM machines is presented. The technique is based on carrier frequency signal injection and proves to be fast, simple and parameter insensitive. It is applied to both salient and very low saliency PM synchronous machines of different power levels. An important step to understanding the implementation is to map the saliency and magnet polarity information as a function of rotor position. A state filter topology is proposed to ensure fast, smooth and robust convergence of the initial position and magnet polarity estimation for a SPMSM with an extremely low saliency ratio. Test results demonstrate consistent performance across different machine types