Mengesha Mamo (PhD)Ayantu Getachew2025-06-192025-06-192025-01https://etd.aau.edu.et/handle/123456789/5600This research presents Sliding Mode Speed Estimator (SMSE) and Fractional Order Sliding Mode Control (FOSMC) for permanent magnet synchronous motors (PMSM) to achieve high performance sensorless control. The SMSE is able to estimate the rotor position and speed. The back electromotive force SMSE is proposed. The estimated rotor position and speed are used to replace the actual values detected by the sensor. The estimation and PMSM modeling su er with uncertainty and chattering hence, need robust control method to work e ciently in the whole working ranges of speed. Sensorless speed control su ers with accuracy speci cally in the low speed region of the PMSM control due-to estimation and modeling defects. Therefore, FOSMC comes into application for enhancing the performance of PMSM during the transient conditions. Hence, the estimation accuracy is tracked within very short settling time of less than 1 second and the robustness against uncertainties is enhanced. This is veri ed with simulation results performed using MATLAB Simulinken-USSPMSMFOSMCSMSEMATLABSimulinkThesis