A HOSM observer with an improved zero-speed position estimation design for surface PMSM sensor-less control

In this paper, an Estimator/Observer Swapping system is proposed, for the surface Permanent Magnet Synchronous Motor (PMSM), to overcome position observability problems at zero speed which is an unobservable state point. The designed observer based on Higher Order Sliding Mode (HOSM) is used in order to ensure the robustness against disturbances and to avoid the chattering phenomenon which is inherent in standard first order sliding mode. The stability and finite time convergence of the developed observer are studied. Various tests are carried out in simulation to highlight the effectiveness and the robustness of the proposed estimation design.