Control of the speed as well as shaping the speed transient response of a surface-mounted Permanent Magnet Synchronous Motor (PMSM) is achieved using the method of feedback linearization and extended high-gain observer. To recover the performance of feedback linearization, an extended high-gain observer is utilized to estimate both the speed of the motor and the disturbance present in the system. The observer is designed based on a reduced model of the PMSM, which is realized through the application of singular perturbation theory. The motor parameters are assumed uncertain and we only assume knowledge of their nominal values. The external load torque is also assumed to be unknown and time-varying, but bounded. Stability analysis of the output feedback system is given. Experimental results confirm the performance and robustness of the proposed controller. We also compare our proposed control method to the cascaded Proportional Integral (PI) speed controller. Then, we show the extension of this control method to solve the problem of sensorless control of PMSMs. The proposed sensorless control method is a back-emf based control scheme. Therefore, we design a high-gain back-emf observer in the Îł-Îø coordinates. Next, we transform the model of the PMSM to the d-q coordinates, which is performed using the estimated position, and close the loop around the currents with relatively fast PI controllers. After that, we reduce the model of the PMSM and design a third order Q-PLL extended high-gain observer as well as the speed feedback controller. Then, we perform a rigorous stability analysis of the closed loop system. Finally, we show simulation and experimental results to verify performance and robustness of the proposed controller.
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