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Wyświetlanie 1-4 z 4
Tytuł:
Initial Rotor Position Detection of Induction Machines Using Feedforward Sensorless Saliency Separation
Autorzy:
Montero, Eduardo Rodriguez
Vogelsberger, Markus
Wolbank, Thomas
Powiązania:
https://bibliotekanauki.pl/articles/1956005.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
induction machine
harmonic compensation
rotor slotting saliency
sensorless control
Opis:
The use of induction machine spatial saliencies for sensorless vector control in the proximity of zero electrical frequency has been extensively researched over the last few decades. A robust technique to extract machine saliencies is called voltage step excitation, and it computes a saliency phasor out of phase current derivatives resulting from specific voltage steps generated by the inverter switching. Within the saliency phasor, all machine saliencies appear superposed. For some machine constructions, multiple saliencies are present, containing information about the spatial, magnetic and geometric state of the machine. Due to its direct relation with the rotor angle and its high accuracy, rotor slotting saliency is often chosen as the sensorless control signal. In order to exclusively access rotor slotting, saliency separation needs to be carried out, with the goal of eliminating all non-control saliencies from the saliency phasor. In this research, feedforward harmonic compensation based on look-up tables (LUTs) is chosen. The idea is to estimate each saliency in relation to amplitude and phase shift once, store such information in a torque-dependent LUT and use it for feedforward compensation. Yet, several saliencies are linked to the rotor position and, thus, the stored phase shift in the LUT is fixed to a defined rotor position at which the saliency estimation was performed. For the feedforward compensation to work during each sensorless start-up, an initial rotor slot detection must be carried out. This paper presents a technique to estimate initial rotor angle based only on the inherent characteristics of the induction machine multi-saliencies and an iterative feedforward compensation process that requires no extra resources and only a few PWM (Pulse Width Modulation) periods to achieve initial slot rotor angle. Experimental results measured at two different test benches prove the high accuracy of the method.
Źródło:
Power Electronics and Drives; 2021, 6, 41; 301-313
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effectiveness of Cue Relevance and Saliency in the Context-Specific Proportion Congruent Effect
Autorzy:
Grajewska, Blandyna Żurawska vel
Powiązania:
https://bibliotekanauki.pl/articles/430820.pdf
Data publikacji:
2014-09-01
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conflict
proportion congruent
cognitive control
relevancy
Opis:
The context-specific proportion congruent (CSPC) effect can be observed when within a block of trials two different ratios congruent-to-incongruent trials are assigned to different variants of stimulus feature (like location or colour). This feature is a contextual cue. CSPC effect is present when congruency effect size is differentiated according to the ratio congruent-to-incongruent trials assigned to specific stimulation parts. In the present paper the relevance and saliency of contextual cues in variants of the flanker task were systematically manipulated, by varying background colour, stimulus colour and luminance, and target-arrow direction as contextual cues. The obtained results support the claim that task-relevancy of the contextual cue is a critical factor in predicting its effectiveness (no CSPC effect for task-irrelevant background, stimuli colour or luminance, and significant CSPC effect for task-relevant target-arrow direction).
Źródło:
Polish Psychological Bulletin; 2014, 45, 3; 380-391
0079-2993
Pojawia się w:
Polish Psychological Bulletin
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic and steady state performance comparison of line-start permanent magnet synchronous motors with interior and surface rotor magnets
Autorzy:
Ogbuka, C.
Nwosu, C.
Agu, M.
Powiązania:
https://bibliotekanauki.pl/articles/141537.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
PMSM
line-start
damper winding
airgap torque
reluctance torque
saliency
Opis:
A comprehensive comparison of the dynamic and steady state performance characteristics of permanent magnet synchronous motors (PMSM) with interior and surface rotor magnets for line-start operation is presented. The dynamic model equations of the PMSM, with damper windings, are utilized for dynamic studies. Two typical loading scenarios are examined: step and ramp loading. The interior permanent magnet synchronous motor (IPMSM) showed superior asynchronous performance under no load, attaining faster synchronism compared to the surface permanent magnet synchronous motor (SPMSM). With step load of 10 Nm at 2 s the combined effect of the excitation and the reluctance torque forced the IPMSM to pull into synchronism faster than the SPMSM which lacks saliency. The ability of the motors to withstand gradual load increase, in the synchronous mode, was examined using ramp loading starting from zero at 2 s. SPMSM lost synchronism at 12 s under 11 Nm load while the IPMSM sustained synchronism until 41 seconds under 40 Nm load. This clearly suggests that the IPMSM has superior load-withstand capability. The superiority is further buttressed with the steady state torque analysis where airgap torque in IPMSM is enhanced by the reluctance torque within 90E to 180E torque angle.
Źródło:
Archives of Electrical Engineering; 2016, 65, 1; 105-116
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infrared small-target detection under a complex background based on a local gradient contrast method
Autorzy:
Yang, Linna
Xie, Tao
Liu, Mingxing
Zhang, Mingjiang
Qi, Shuaihui
Yang, Jungang
Powiązania:
https://bibliotekanauki.pl/articles/2201024.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
small target detection
local gradient contrast
visual saliency
infrared image processing
kontrast lokalny
wyróżnienie wizualne
obrazowanie w podczerwieni
Opis:
Small target detection under a complex background has always been a hot and difficult problem in the field of image processing. Due to the factors such as a complex background and a low signal-to-noise ratio, the existing methods cannot robustly detect targets submerged in strong clutter and noise. In this paper, a local gradient contrast method (LGCM) is proposed. Firstly, the optimal scale for each pixel is obtained by calculating a multiscale salient map. Then, a subblockbased local gradient measure is designed; it can suppress strong clutter interference and pixel-sized noise simultaneously. Thirdly, the subblock-based local gradient measure and the salient map are utilized to construct the LGCM. Finally, an adaptive threshold is employed to extract the final detection result. Experimental results on six datasets demonstrate that the proposed method can discard clutters and yield superior results compared with state-of-the-art methods.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2023, 33, 1; 33--43
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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