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Author: search.filters.author.Wongvanich, NapasoolSubject: search.filters.subject.nonlinear control

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    Observer-less Fixed-Time Speed Control For Permanent Magnet Synchronous Motors with matched-mismatched disturbances
    (2025-01-01)
    Cholahan, Varin
    ;
    Wongvanich, Napasool
    ;
    Tangsrirat, Worapong
    This paper presents a state-dependent Variable Exponent Coefficient Sliding Mode Control (VECFSMC) By inducing fixed-time stability analysis, the proposed state-dependent sliding surface provides not only system stability but also a quick response in a fixed period of time as well as counteract with matched and mismatched disturbances. The proposed sliding mode control strategy does not use observers to estimate the disturbances. The designed sliding mode surface possesses robustness properties which is sufficient to cope with both matched and mismatch disturbances in a period of fixed time. Firstly, the mathematical model of permanent magnet synchronous motor and the mathematical background of variable exponent coefficient are demonstrated theoretically. Secondly, the state-dependent sliding surface with variable exponent coefficient is designed. The controller that can manipulate both the speed of PMSM and matched-mismatched disturbances is constructed. Lyapunov function is applied to assess the stability of the proposed method. Finally, a numerical simulation with PMSM drive shows fast convergence, good robustness against both matched and mismatched disturbances. The proposed fixed-time controller with this observer-less method offers high efficiency and offers not too complicated control solution comparing to the other fixed-time and finite-time methods with a small number of parameters.
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    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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    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.