State and disturbance observers in mechanical sensorless control of PMSM

Linear and nonlinear observers have found wide interest in mechanical sensorless control of PMSM. In this paper, we study the application of nonlinear state observers and linear disturbance observers to the sensorless control of PMSM modeled in a particular Park δ-γ reference frame. We prefer this frame because of its non-alternative variables. The stability of the augmented system is analyzed and the stability conditions are given. In order to improve the robustness of the system with respect to the parameter variations, an on-line parameter identification method may be added to presented observers. The simulation and experimental results illustrate the validity of the analytical approach and the efficiency of the proposed methods.