Fictitious Flux and a Globally Stable Observer for Sensorless Control of Synchronous Reluctance Motors

The challenging problem of globally stable position and speed estimation of synchronous reluctance motors is solved with the proposed flux observer. Global stability is assured by the introduction of a new fictitious flux variable in the motor's model. Rotor position and speed are estimated from the fictitious flux using a vector phase-locked loop. Theoretical results are verified by simulation which shows stable estimation and good sensorless performances under various operating conditions.