Enhanced self-sensing capability of permanent-magnet synchronous machines: A novel saliency modulation rotor end approach

This paper investigates a novel rotor configuration of a permanent-magnet synchronous machine (PMSM) in which a saliency modulation rotor end is added to the machine rotor to improve the self-sensing capability. The saliency-based self-sensing control method is widely adopted for position estimation at stand-still and low speed range. However, the performance is heavily affected by saturation effects for conventional PMSMs, because the machine saliency variates with increased fundamental stator flux under loaded operation. The proposed scheme provides an additional space anisotropic to the rotor. Saliency modulation of the rotor end is electrically asynchronous with the machine fundamental reference frame. Hence the tracked machine saliency provided by the rotor end is no longer affected by saturation effects. In addition, for medium and high speed ranges, the rotor end saliency can be modulated with the fundamental voltage and the rotor position can be tracked without superposed injection. A genetic algorithm optimization environment joined with finite element analysis allows obtaining optimized rotor end geometry for better position signal quality. The expected self-sensing performance is validated by experimental results.