This paper proposes a smooth switching scheme with separate control strategies on low speed mode and high speed mode for permanent magnet synchronous motor (PMSM) sensorless control to improve the overall performance in full speed range. Constant voltage/frequency tuning method is used on low speed mode because the rotor position can hardly be estimated precisely at low speed. Along with the increasing speed, the control strategy can be switched to high speed mode smoothly when current and speed meet the given requirements. In this high speed mode, the current tracking with a sliding mode observer (SMO) and speed tracking with a sliding mode controller (SMC) are handled, respectively. Experimental demonstration is presented to show the desired performance in full speed range of the PMSM sensorless control using the proposed control scheme in this paper.
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http://dx.doi.org/10.1016/j.isatra.2015.07.013 | DOI Listing |
Terahertz on-chip pathway is crucial for next-generation wireless communication, terahertz integrated circuits, and high-speed chip interconnections, yet its development is impeded by issues like channel crosstalk and disordered scattering. In this study, we propose and experimentally demonstrate a terahertz on-chip topological pathway that exhibits exceptional transmission robustness, unaffected by structural curvature. The pathway is constructed using a subwavelength structure that combines the benefits of topological properties, such as broadband single-mode transmission and linear dispersion, with the field localization effects of periodic metal structures.
View Article and Find Full Text PDFHigh-speed silicon traveling-wave Mach-Zehnder modulators (MZMs) are key components to support optical fiber communication. However, one major challenge with all-silicon MZMs is to achieve efficient high-speed electro-optic (EO) modulation. The reported 3 dB bandwidth of silicon MZMs are generally below 70 GHz, with half-wave voltage ( ) around 5 V or larger, which can not support future 200 Gbaud data transmission.
View Article and Find Full Text PDFWe propose a refractive index (RI) sensing method that leverages the frequency multiplication capability of a photocarrier terahertz (PC-THz) comb to enhance sensitivity and speed. By incorporating a PC-THz comb as a frequency multiplier for a RI-sensing optical frequency comb (OFC), we achieve significant amplification of the RI-dependent mode spacing ( ) shift. Our results show a 3100-fold increase in sensitivity, confirmed through the accurate measurement of ethanol-water solutions with varying concentrations.
View Article and Find Full Text PDFAnal Chem
January 2025
ICGM, Univ. Montpellier, CNRS, ENSCM, 34000 Montpellier, France.
In this contribution, we apply our newly developed ball-milling platform, which combines Raman spectroscopy and thermal (IR) imaging, as well as acoustic and high-speed optical video recordings, to the synthesis and transformation of citric acid-isonicotinamide (1:2) cocrystal polymorphs in transparent PMMA jars. Particularly, we demonstrate how Raman, temperature, acoustic, and video data are complementary and enable detection and connection of chemical and physical events happening during ball-milling in a time-resolved manner. Importantly, we show that the formation of the three cocrystal polymorphs can be detected through acoustic analyses solely.
View Article and Find Full Text PDFSci Rep
January 2025
China Academy of Railway Sciences Co. Ltd, Beijing, 100081, China.
The construction of tunnels can easily trigger the reactivation of old landslide bodies, posing a threat to the transportation safety. In this study, using methods such as engineering geological investigation, slope deformation monitoring, deep displacement monitoring, and numerical simulation, the interaction between landslides and tunnels was investigated from the perspective of landslide deformation and failure characteristics. The Walibie Tunnel (WLBT) of Shangri-La to Lijiang (XL) expressway was taken as an example.
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