Parameter Design and Convergence Analysis of Flux Observer for Sensorless PMSM Drives

Position observer design is one of the most important tasks for sensorless PMSM drives. In this paper, we apply extended state observer (ESO) to estimate the PMSM angular position. For the operation of constant velocity, we use the linearization technique to study the error dynamics and design parameter tuning strategies for fast convergence and robustness against adverse effects. We further analyze the equilibria distributions of the estimation error dynamics and ensure that the origin is the only stable equilibrium. For velocity tracking, the ESO estimator can be readily extended to deal with this case and its global convergence is guaranteed by the results of slowly varying systems. The experimental results on a 750 W motor drive demonstrate the efficacy of the ESO position observer.