In this thesis, direct torque and flux control of three-phase synchronous reluctance motor (SynRM) drives is improved based on adaptive nonlinear control. The SynRM drive is supplied with a two level symmetrical space vector modulation (SVM) voltage source inverter. Two estimation laws are obtained by adaptive input-output feedback linearization (AIOFL) for detecting the stator d and q axis inductances. The overall stability of this controller is analytically proved based on Lyapunov theory. In addition, a flexible direct torque control (DTC) based on Variable Structure (VS) and SVM is presented for sensorless SynRM Drives. According to this method, a sliding mode-plus-PI controller is designed for torque and flux control in stator flux reference frame, respectively. The proposed controller is able to reduce the torque, flux, current and speed pulsations during steady-state behavior while the fast response and robustness merits of the justify; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr" Key Words Synchronous Reluctance Motor, Direct Torque Control, Adaptive Input-output Feedback Linearization, Variable Structure, Efficiency Optimization
