Sliding Mode Natural Speed Observer With Hybrid Flux Concept for Sensorless PMSM Drives

This article addresses the sliding mode reduced-order natural speed observer (NSO) design for position sensorless drive with permanent magnet synchronous motor (PMSM). Perform stability analysis on the original reduced-order NSO, include parameter inaccuracies and velocity discrepancies. The NSO is asymptotically stable alone under steady-state conditions. A feedback correction term and a sliding gain are necessary to improve robustness and suggest a more pragmatic speed observer design. Building on this, the sliding mode reduced-order NSO and the hybrid flux observer (HFO) are cascaded together. This leads to a sensorless algorithm that requires adjustment of only three parameters. By integrating the active flux principle, the proposed sensorless method can be applied to both interior PMSMs and surface PMSMs. Finally, the experimental validation is carried out on a platform of 750W PMSM drive and the proposed method is efficient.