Sensorless Synchronous Motor Drives: A Review of Flux Observer-Based Position Estimation Schemes Using the Projection Vector Framework

This article reviews six fundamental-wave excitation sensorless techniques for synchronous machines reported in the literature. All rely on a hybrid flux observer scheme, combining voltage and current-models of machine, use error signal to track rotor phase angle rotational speed. A common mathematical framework with magnetic nonlinearity is constructed stability analysis where each studied technique represented by unique projection vector. The dynamics position investigated regions instability are identified scheme under similar operating conditions. Experimental validation support 1.1-kW reluctance machine test-bench.