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    Item type:Publication,
    A Novel Practical Fixed-Time Speed Control of Permanent Magnet Synchronous Motors with Input Saturation
    (2025-01-01)
    Cholahan, Varin
    ;
    Wongvanich, Napasool
    ;
    Tangsrirat, Worapong
    In this article, we focus on a control problem for the speed control of a permanent magnet synchronous motor (PMSM). An antisaturation adaptive fixed-time nonsingular sliding mode control (AFFTNSM) with disturbance estimation compensation is designed for a class of second-order nonlinear systems to improve PMSM system performance. Firstly, a novel fast fixed-time nonsingular sliding mode surface is chosen based on the error dynamic equation. Then, a practical fixed-time sliding mode control algorithm is proposed where the stability of the proposed controller is demonstrated to show the convergence of the velocity tracking error to a neighborhood of the origin in fixed-time. The implementation of feedforward compensation of disturbance enhances the dynamic performance of the fast fixed-time nonsingular sliding mode control rule, resulting in reduced chattering phenomena. Numerical simulation results are provided to verify the efficiency of the proposed method.
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    Item type:Publication,
    Robust Practical Fixed-Time Control and Application to DC-DC Buck Converter
    (2024-01-01)
    Wongvanich, Napasool
    ;
    Cholahan, Varin
    ;
    Tangsrirat, Worapong
    This work presents an adaptive fixed-time speed controller of permanent magnet synchronous motors for a class of second-order nonlinear systems based on practical fixed-time stability, in which a sliding mode surface with a constant exponent coefficient is designed to avoid singularities and achieve a fast convergence rate. This method is easy to implement compared to other sophisticated fixed-time controllers. In addition, the upper bound of control inputs is selected to prevent saturation limitations. Following that, the Lyapunov function expresses the close-loop stability of a practical fixed-time controller. An adaptive disturbance rejection with smooth function is presented to attenuate the total disturbances, chattering, and steady-state error. The tracking error is integrated into a bounded residual region within a specified time. Finally, numerical simulations are given to verify the performance of both controller and disturbance rejection mechanisms.
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    Item type:Publication,
    The Effect of Media in Mitigating Epidemic Outbreaks: The Sliding Mode Control Approach
    (2022-05-01)
    Wongvanich, Napasool
    Ever since the World Health Organization gave the name COVID-19 to the coronavirus pneumonia disease, much of the world has been severely impact by the pandemic socially and economically. In this paper, the mathematical modeling and stability analyses in terms of the susceptible–exposed–infected–removed (SEIR) model with a nonlinear incidence rate, along with media interaction effects, are presented. The sliding mode control methodology is used to design a robust closed loop control of the epidemiological system, where the property of symmetry in the Lyapunov function plays a vital role in achieving the global asymptotic stability in the output. Two policies are considered: the first considers only the governmental interaction, the second considers only the vaccination policy. Numerical simulations of the control algorithms are then evaluated.