Improved Fixed Time Sliding Mode Observer for Sensorless Operation of Permanent Magnet Synchronous Generator Wind Turbine

Abstract

This article presents a refined fixed time sliding-mode observer (FTSMO) developed for wide-speed sensorless control of permanent magnet synchronous generator wind turbines (PMSG-WTs). The proposed approach enables the estimation of speed and position in the αβ frame with the help of Arc-tan block, which is a requirement in back-electromotive force (EMF) estimation-based methods. This not only lightens the computational load on the control system but also simplifies the challenge of determining PLL design parameters. Moreover, an innovative terminal sliding surface is utilized to improve the reaching phase, resulting in a faster convergence rate with higher accuracy in estimations compared to conventional terminal sliding techniques. The finite-time convergence of the proposed estimation scheme is verified using the Lyapunov theorem, ensuring that estimation errors converge to zero within a specified time frame, regardless of initial conditions. MATLAB/Simulink simulations are carried out to assess the performance of the sensorless method on a 18-kW PMSG-WT. The results demonstrate a quicker convergence time relative to Extended Kalman Filter (EKF) observers.