This paper focuses on the speed control of a permanent magnet synchronous motor (PMSM) for electric drives with model uncertainties and external disturbances. Conventional sliding mode control (CSMC) can only converge asymptotically in the infinite domain and will cause unacceptable sliding mode chattering. To improve the performance of the PMSM speed loop in terms of response speed, tracking accuracy, and robustness, a hybrid control strategy for a fixed-time-convergent sliding mode controller (FSMC) with a fixed-time-convergent sliding mode observer (FSMO) is proposed for PMSM speed regulation using the fixed-time control theory. Firstly, the FSMC is proposed to improve the convergence speed and robustness of the speed loop, which can converge to the origin within a fixed time independent of the initial conditions. Then, the FSMO is used as a compensator to further enhance the robustness of the speed loop and attenuate sliding mode chattering. Finally, simulation and experimental results show that the proposed method can effectively improve the dynamic performance and robustness of the PMSM speed control system.
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http://dx.doi.org/10.3390/s24051561 | DOI Listing |
ISA Trans
December 2024
Department of Automation, Key Laboratory of System Control and Information Processing of Ministry of Education, Key Laboratory of Marine Intelligent Equipment and System of Ministry of Education, Shanghai Engineering Research Center of Intelligent Control and Management, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address:
This paper presents the design of a disturbance rejection-based control strategy for a quadrotor unmanned aerial vehicle subject to model uncertainties and external disturbances described by turbulent wind gusts of severe intensity. First, an extended state observer is introduced to supply full-state and total disturbance estimations within a fixed time regardless of initial estimation errors. Then, an adaptive non-singular fast terminal sliding mode controller with a single-gain structure is proposed to reduce the tuning complexity and drive the pose of the rotorcraft while providing practical finite-time convergence, robustness to bounded external disturbances, non-overestimation of its control gain, and chattering attenuation.
View Article and Find Full Text PDFBMC Psychiatry
December 2024
Department of Radiology, College of Medicine, The First Affiliated Hospital, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang, 310003, China.
Objective: Major depressive disorder (MDD) is known to be characterized by disrupted brain functional network connectivity (FNC) patterns, while the dynamic change mode of different functional networks is unclear. This study aimed to characterize specific dynamic alterations pattern on intrinsic FNC in MDD by combining static FNC (sFNC) and dynamic FNC (dFNC).
Methods: A total of 48 first-episode drug-naïve MDD and 48 matched healthy controls (HCs) were included in this study.
Heliyon
October 2024
Department of Electrical Engineering, Marwadi University, Rajkot-Morbi Highway, Rajkot, 360003, Gujarat, India.
The Unified Power Quality Conditioner (UPQC) is a promising solution for mitigating multiple Power Quality(PQ) issues in distribution systems, including harmonics, poor power factor, voltage sag/swell and voltage imbalance. The conventional Sliding Mode Controller (SMC) in UPQCs suffers from wide switching frequency variations, chattering problems, and inherent active and reactive power coupling. This study proposes a nonlinear control method, Sliding Mode-based Direct Power Control (SMC-DPC), for the simultaneous regulation of the shunt and series compensators in a UPQC.
View Article and Find Full Text PDFHeliyon
October 2024
School of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan Hebei, 056038, China.
The hydraulic support pushing mechanism is the primary equipment utilized in coal mine backfill operations, playing a crucial role in enhancing filling efficiency, ensuring a stable filling body, and managing gob safety. This paper focuses on analyzing the dynamic model and the interrelationship of the hydraulic cylinder, which serves as the power source for the pushing mechanism. To address the intricate coupling effects arising from the hydraulic cylinders and the displacement-force induced by the shared pump, this study employs feedforward compensation for decoupling analysis.
View Article and Find Full Text PDFQRB Discov
December 2024
Department of Chemistry, University of Basel, Basel, Switzerland.
Single Molecule Förster Resonance Energy Transfer (smFRET) is a popular technique to directly observe biomolecular dynamics in real time, offering unique mechanistic insight into proteins, ribozymes, and so forth. However, inevitable photobleaching of the fluorophores puts a stringent limit on the total time a surface-tethered molecule can be monitored, fundamentally limiting the information gain through conventional smFRET measurements. DyeCycling addresses this problem by using reversibly - instead of covalently - coupled FRET fluorophores, through which it can break the photobleaching limit and theoretically provide unlimited observation time.
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