Wide-Speed Range Operation of Position-Sensorless SynRM Drives with High-Frequency Signal Injection and Hybrid Flux Observer

This study proposes a wide-speed-range sensorless control scheme for synchronous reluctance motors (SynRMs) that integrates high-frequency square-wave injection and hybrid flux observation. In the zero-to-low speed domain (<5% rated speed), a high frequency square-wave voltage injection method is implemented to extract rotor position through saliency-tracking effects. For medium-high speed operation (>15% rated speed), a hybrid flux observer combining current model precision and voltage model robustness dynamically estimates the rotor information. Furthermore, to achieve seamless transition across diverse speed regimes and improve dynamic stability, a hybrid modulation strategy is implemented in the proposed system. Experimental validation conducted on a 7.5-kW laboratory-developed synchronous reluctance motor drive testbed corroborates the efficacy of the sensorless control methodology.