Sensorless Control System for Permanent Magnet Synchronous Motor Based on Improved Sliding Mode Control

In the sensorless control system of permanent - magnet synchronous motors (PMSM), the PI-controlled speed loop has long been plagued by problems such as speed overshoot, jitter, and three-phase current distortion. This study breaks new ground by presenting a revolutionary non-singular fast-terminal sliding-mode controller (NFTSMC). NFTSMC introduced here represents a paradigm shift in control design. Its approach rate function, a distinct innovation, combines a switching function that governs the approach phase and an exponential function that prevails during the sliding stage. Coupled with a uniquely improved non-singular fast-terminal sliding-mode surface, this NFTSMC, when integrated as a speed loop, effectively curtails the speed overshoot and markedly elevates the system's anti-interference capabilities. Subsequently, an innovative leap forward is made with the introduction of the Improved Sliding-Mode Observer (ISMO). Through an unprecedented optimization of the observer design, the system can achieve sensor-less operation by precisely estimating the rotational speed and rotor position using ISMO. Ultimately, the simulation results obtained from MATLAB/Simulink serve as irrefutable proof of the superiority of this novel approach. In comparison to the traditional vector control system, the vector system under the control of NFTSMC and ISMO exhibits a significantly smaller speed overshoot, reduced current distortion, and substantially stronger anti-interference ability, underscoring the originality and efficacy of this groundbreaking design.