This paper presents an innovative observer-based sliding mode controller specifically designed for effective current tracking in brushless doubly-fed induction generator wind turbines. The adoption of sliding mode control is motivated by the inherently nonlinear dynamics of the BDFIG system, which pose challenges to conventional control methods. By employing a dynamic sliding mode controller, a smooth and reliable control signal is achieved, enhancing system performance and stability. Additionally, a discrete-time sliding mode disturbance observer is introduced to provide accurate estimation of system uncertainties. A notable advantage of this observer lies in its time-discontinuous nature, which simplifies its implementation on digital processors. This feature is particularly advantageous as it incorporates the sampling time directly into the design phase, ensuring compatibility with digital processing requirements. The proposed controller's performance is thoroughly validated through detailed computer simulations, demonstrating its robustness and effectiveness in managing the nonlinear dynamics of BDFIG wind turbines.

A new finite time second order terminal sliding mode controller is proposed for a magnetic levitation train in this paper. Sliding mode which is nonlinear and robust controller is used because of existent the nonlinearity and uncertain terms in the dynamics of the maglev train system. To overcome on the chattering and produce a smooth control signal, the famous super twisting algorithm is used. Also the proposed control law is consists of two adaptive terms to estimate uncertain function. Moreover, the proposed controller insures the finite time stability of sliding surface and the finite time stability of the errors is achieved too, due to use terminal sliding mode theory. Simulations are performed to evaluate the controller and its high accuracy. Robustness of the proposed control scheme against uncertainty is also investigated.

Controlling brushless DC motors enhances their efficiency and accuracy. Recently, the nonlinear control of these motors has garnered significant attention from researchers. This article presents the extraction of the nonlinear model of a brushless DC motor and the conversion of three-phase coordinates to d-q space, leading to the design of a nonlinear controller and a discrete-time observer. To maximize efficiency, a linear feedback nonlinear controller is designed to control the current along the d-axis, while a feedback nonlinear controller is used to control the shaft angle. The shaft position controller utilizes load torque estimation information. The developed observer is designed in discrete time to estimate system states and load torque. Software and processor in the loop simulation results confirm the performance of the observer-based control system. Additionally, the discrete-time nature of the observer facilitates easy implementation, and the article concludes with the results of the controller implementation based on the proposed observer and the processor in the loop simulation.