In this paper, the design and implementation of adaptive speed controller for a sensorless synchronous reluctance motor (SynRM) drive system is proposed. A combination of well-known adaptive input-output feedback linearization (AIOFL) and adaptive backstepping (ABS) techniques are used for speed tracking control of SynRM. The AIOFL controller is capable of estimating motor two-axis inductances (Ld, Lq), simultaneously. The overall stability of the proposed control and Persistency of Excitation (PE) condition are proved based on Lyapunov theory. In the proposed control drive system, the maximum torque control (MTC) scheme and constant current in inductive axis control (CCIAC) are applied to generate the motor d and q axis reference currents which are needed for the AIOFL controller. In addition, an ABS speed controller is designed to compensate for the machine parameter uncertainties and load torque disturbances. Another contribution of this paper is to estimate the rotor speed and position in very low speed by using 1) a simple technique for eliminating the voltage sensors, 2) a simple method for online estimation of the stator resistance, and 3) modeling the voltage drop of the inverter power switches. Finally, the validity and capability of the proposed method are verified through simulation and experimental studies.

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