1,720,962 research outputs found
Direct Voltage Control of an Interior Permanent Magnet Synchronous Motor in Overspeed Conditions
No full textElectric machines contribute to efficiency, convenience, and sustainability in various applications across our modern lives, such as electric public transportation, renewable energy, industrial applications, home appliances, and many more.
Specifically, permanent magnet synchronous machines (PMSMs) have high power density, high efficiency, high torque, and a fast-dynamic response. These features make this kind of machine very attractive for electric propulsion like automotive electrical power steering applications, which play a significant role in being a perfect alternative to internal combustion engines (ICEs) because of the environmental implications and the scarcity of fuel resources for these engines.
These machines must fulfill specific characteristics to achieve high performance for such applications. Because of their numerous benefits, including robustness, potential operation, reduced control complexity, and high-power density in the high-speed range, most manufacturers prefer to employ permanent magnet synchronous machines (PMSMs) in multi heavy duty and smart applications.
On the other hand, these aforementioned synchronous machines experience nonlinearity due to magnetic saturation phenomena because of their mechanical structure and volume optimization needs. Additionally, aging operation temperatures and fabrication tolerances cause deviations and mismatches in some electric parameters when they reach their voltage thresholds. Therefore, precise controllers need to be developed and optimized to achieve the most effective and reliable torque control behavior without affecting these parameters of the electric machine even while operating at its maximum capacity. In this case study, the back electromotive force, which proportionally increases as the machine rotation speed increases, should be considered during the high-speed range, and, due to the voltage limit of the power source and inverter, flux weakening control must be carried out to prevent any excess electromagnetic flux.
This thesis presents a comparative study of the main benefits and drawbacks of various electric machines used in industrial applications. In the beginning, PMSMs are discussed because they satisfy particular requirements for various applications, such as electric vehicle (EV) propulsion systems, making them more desirable in such similar fields as one of many critical applications in which these machines could be used. The most popular control strategies and techniques of the interior permanent magnet synchronous machines (IPMSMs) are then thoroughly reviewed and analyzed.
The primary objective of this thesis's research is to validate how to employ the developed direct voltage control (DVC) method to maintain maximum torque while keeping high performance, particularly beyond the base speed and towards higher speed ranges in the IPMSM machine, by implementing the formulas found in the literature. An analysis of the proposed control method is performed compared to the widely used field-oriented vector control strategy to demonstrate its simplicity and capability.
The flux weakening and the maximum torque per volt (MTPV) working regions of IPMSM should be maintained at high speeds to maximize torque while efficiently minimizing the stator flux, so by applying the literature's MTPA, FW, and MTPV regions formulas to the suggested
DVC through implementing a developed MATLAB coding and Simulink model scheme, then evaluating the outputs and comparing them with the results we got from the popular FOC method using the same equations. The final experimental results, with an additional quantitative efficacy comparison for both control methods, reveal the proposed method's ability. Simulations are implemented using experimental data from an IPMSM machine with five-horse nominal power
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Simplified Maximum Torque per Ampere Trajectory Tracking for Permanent Magnet Synchronous Machine Drives
No full textThe permanent magnet synchronous machine is considered one of the significant electric machines used in different applications due to its high torque density, high power density, high efficiency, and low maintenance. Due to the PM synchronous machines' design, the control system can drive the motor to deliver high torque to mechanical loads with the lowest current, which is called the maximum torque per ampere (MTPA) control method, and operate the generator to inject maximum electric energy into the grid at any mechanical power, which is called the maximum power extraction (MPE). MTPA control can be achieved by direct voltage control. Therefore, a simple direct voltage MTPA control strategy is suggested with a thorough insight analysis to define the control gains analytically, which simplifies the control ultimately and makes it more suitable for low-cost real-time implementation compared to other methods. The proposed method tracks the MTPA trajectory by finding the optimal pair of voltage angle and amplitude for each motor's speed and torque conditions. This is achieved without the need for any current control loop, which makes the technology simple to a great extent, contrary to most methodologies, but this simplicity is made possible by ignoring transient terms that guarantee MTPA only at steady-state. To overcome this limitation, simple dynamic direct control approaches are proposed to compensate for transient terms, making MTPA operation possible in all operating conditions with/without current sensors. The proposed strategies are applied to an interior permanent magnet synchronous motor (IPMSM) for industrial and electric vehicle applications and a surface-mount permanent magnet synchronous generator (SPMSG) for wind energy conversion system implementations. To illustrate the suggested control methods' capability, comparative studies are conducted against the popular MTPA vector control strategy. Experimental results for various situations reveal the suggested MTPA controllers' ability. Additionally, to quantitatively assess the MTPA trajectory tracking accuracy, the proposed control methods are compared using a qualification metric with energy consumption and energy efficiency studies
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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