A sliding-mode-observer for encoderless direct model predicitve control of PMSGs

This paper presents a study and experimental verification of an encoderless direct model predicitve control (DMPC) strategy for permanent magnet synchronous generators (PMSGs) based variable speed wind turbines (VSWTs). The proposed sensorless method is based on a sliding-mode observer (SMO) that estimates the position and speed of the rotor from the back electromotive force (EMF). The proposed SMO is presented in discrete form, where a sigmoid function holds as switching function, and the stability is verified using the Lypunov function technique. Experimental results for speed and torque changes and, furthermore, for parameter variations are presented to verify the feasibility of the proposed encoderless method.