This paper proposes a novel non-singular predefined-time control method for permanent magnet synchronous motor (PMSM) servo systems under disturbances. A non-singular predefined-time sliding mode manifold is designed to eliminate singularity issues while enabling adaptive switching under varying conditions, with stability achieved within a user-defined time frame. Based on this sliding mode manifold, a controller is developed to ensure predefined-time convergence in both reaching and sliding phases. Lyapunov-based analysis guarantees predefined-time stability and practical predefined-time stability, reducing the convergence domain. Simulation results validate the method’s effectiveness, robustness, and practical applicability in achieving predefined-time performance.

This article proposes an event-triggered generalized super-twisting sliding mode disturbance rejection control strategy for permanent magnet synchronous motors (PMSMs), aiming to ensure precise position tracking while efficiently conserving communication resources. A unified event-triggering mechanism facilitates the simultaneous transmission of measurement and actuator signals, effectively implementing feedback-control bidirectional triggering. Furthermore, the entire control strategy is updated based on triggered state information. It incorporates a generalized super-twisting controller characterized by a simple structure and smooth dynamic performance, in addition to a neural network observer and a high-gain observer designed to estimate lumped disturbances and enhance system robustness. The practical stability of the closed-loop system, the boundedness of the signals, and the Zeno-free execution of triggering sequences are rigorously verified. Finally, experimental results on a PMSM validate the superiority of the proposed control approach in terms of transient-state position tracking, steady-state smoothness, communication efficiency, and robustness.

In this article, an observer-based prescribed performance speed control method is proposed for permanent magnet synchronous motors. A transformed speed error is introduced and a suitable controller is designed to make it converge to zero, while guaranteeing the original speed error evolves strictly within a prescribed region. The controller is designed based on a backstepping approach. A linear extended state observer is applied to estimate and feed forward the external constant load disturbance to improve robustness. A data-driven radial-basis function neural network is proposed to approximate the nonlinear dynamic caused by parameter uncertainties and periodic-changing disturbance by deploying real-time and historical data. The stability analysis is based on Lyapunov's control theory. Experimental results verify the effectiveness and advantages of the proposed control scheme.

This paper presents a model-free predictive current controller for permanent magnet synchronous motors. The dynamic model of the motor currents is represented using an ultra-local model, where all system parameters, nonlinear terms, and other unmodeled dynamics are encapsulated into two lumped functions. These functions are estimated online using a second-order fixed-time sliding mode observer, allowing for system model estimation without requiring exact knowledge of the system parameters in advance. Subsequently, a predictive controller is designed by taking into consideration the inherent one-step delay. Simulation results are presented to showcase the effectiveness and efficacy of the proposed approach.

In this paper, the fixed-time control problem of DC-DC buck converter systems with mismatched disturbances is investigated. Firstly, the sliding mode fixed-time observers are constructed to estimate the matched and mismatched disturbances of the systems. Secondly, a novel segmented terminal sliding mode control (TSMC) variable considering the mismatched disturbance of the system is designed based on the observations. To improve the tracking performance, a new second-order fixed-time reaching law is proposed. Then, in order to make the DC-DC buck converter systems with mismatched disturbances achieve accurate control in a fixed-time independent of the initial state, a novel fixed-time nonsingular TSMC based on the fixed-time observers is proposed. Finally, comparative experiments are conducted to verify the effectiveness and practicality of the proposed control strategy.

In this paper, a high-order nonlinear disturbance observer-based fractional-order sliding mode control (FOSMC) strategy is proposed for DC/DC buck converters in the presence of mismatched disturbances, ensuring the properties of both stability and dynamic performance. Traditional sliding mode control can deal with matched disturbances while achieving desired closed-loop performance, unfortunately it is particularly sensitive to mismatched disturbances. In the proposed control structure, two nonlinear disturbance observers are constructed to estimate both matched and mismatched disturbances in finite time. Then, the estimated variables are used for the fractional-order sliding mode surface design, where a super twisting sliding mode controller is designed to drive the states of the system to track their desired values. Comparing with the traditional SMC, the proposed method not only reduces the sensitivity of the system to mismatched disturbance, but also improves the transient performance of the system. Simulation and experimental results have comprehensively illustrated the feasibility and effectiveness of the proposed strategy.