Sensorless Control of PMSM With Improved Adaptive Super-Twisting Sliding Mode Observer and IST-QSG

In this paper, to enhance speed estimation accuracy and restrain the chattering in sensorless control of permanent magnet synchronous motor (PMSM), an improved adaptive super-twisting algorithm-based sliding mode observer (IAST-SMO) and a novel quadrature signal generator based on improved super-twisting algorithm (IST-QSG) is proposed. Firstly, by introducing the linear terms and adaptive gains, a new super-twisting sliding mode observer is proposed to estimate the back Electromotive Force (EMF), which solves the problems of harmful chattering. Meanwhile, the proposed adaptive method has the high estimation accuracy in a wide speed range. Furthermore, the adaptive gains are proven to satisfy the stability conditions. Then, to eliminate the noise of back-EMF and improve the estimation accuracy, the second-order generalized integrator-based quadrature signal generator(SOGI-QSG) is often used to filter back-EMF, but due to the problem of its estimated speed feedback, the estimated rotor position error will become larger. To solve the problem, an IST-QSG is proposed to extract the smooth back-EMF, and the accuracy of speed estimation is significantly increased. Finally, the comparative experiments in different conditions confirm that the proposed sensorless control strategy exhibits excellent feature in terms of position and speed estimation accuracy, dynamic performance, and robustness.