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Direct analysis of induction motors using finite element
Get PDFThis paper describes two novel Finite-Element procedures for squirrel cage Induction Motor performances prediction. The on-load analyses are carried out performing magnetostatic simulations in order to consider carefully the iron saturation in all machine parts, in each working point. In the first Finite-Element procedure, two iterations are needed to catch the right current distribution in stator and rotor windings and derive the performances. Motor dq currents are imposed according to the machine model in the rotor flux reference frame. A further improved analysis technique will be described, in which a single Finite-Element simulation, closely linked with the analytical
model, is enough to derive the motor on-load behavior. These procedures are suitable for the analysis of Induction Motors in any operating condition: grid-connected, controlled or in V/Hz operation. In this paper the analysis technique has been applied to analyze a grid fed motor; experimental tests have been carried out to verify the Finite-Element procedures results
Measures and Simulations of Induction Machines Flux Linkage Characteristics Based on Rotor Field Orientation
No full textFast Mapping Procedure for Synchronous Reluctance Motors via Magnetic Coenergy Reconstruction Method From Boundaries Dataset
No full textThe paper aims to present a method for forecasting flux linkages and torque maps using only the measured dataset at the boundaries. The experimental mapping technique integrates a sequence of tests to measure self-axis saturation characteristics, coupled with a magnetic model based on co-energy principles. This approach, in addition to being fast because requires only a few tests (measurements are solely necessary along the map boundaries), intrinsically addresses cross-saturation effects. The accuracy of the method has been compared with the reference measurements from the constant-speed method applied to a 3 kW synchronous reluctance machine. Lastly, a procedure based on the same tests is described useful for accurately estimating position errors introduced by the rotor locking system
A Fast and Direct Analysis of Three-Phase Induction Motors Using Finite Element
Get PDFA new finite-element technique for squirrel cage Induction Motor features analysis is presented in this paper. Motor performances are directly predicted performing on-load test simulations, in several working points. The finite-element analyses are carried out imposing both stator and rotor currents. Thus, only magnetostatic simulations are needed to get the electromagnetic quantities, such as torque and slip. Saturation phenomena can be considered in any operating conditions under load, with short computational time. In each motor working point, a very fast finite-element procedure, closely linked with the analytical machine model, is used to catch the proper current
distribution in stator and rotor slots. It allows the motor performances to be predicted without the preliminary knowledge of the machine equivalent circuit parameters. Experimental tests are carried out and reported in order to verify analysis results
Cage Losses in Induction Motors Considering Harmonics: A New Finite Element Procedure and Comparison With the Time-Domain Approach
No full textThe cage losses in induction machines due to spatial or time harmonics in the air-gap field are a crucial parameter for a precise estimation of the machine efficiency. Using finite element, the common approach to consider the overall cage losses, by performing complete time-domain analyses. Alternatively, a rough estimation is achieved introducing equivalent parameters in the circuital model. In this article, a methodology for cage losses computation due to air-gap spatial field harmonics is described. The proposed finite element procedure is faster than the time-domain analysis since it is based on magneto-static and linear time-harmonic simulations to carefully consider the iron saturation and compute the induced currents in a specific working point. In the article, a detailed procedure description and comparison with respect to the time-domain approach is reported
Fast Flux Mapping Technique for Synchronous Reluctance Machines: Method Description and Comparison With Full FEA and Measurements
No full textThis paper describes a fast approach for synchronous reluctance machine flux linkage mapping considering the cross saturation effects. The rapid prediction of the flux maps ?(d)(i(d), i(q)) and ?(q)(i(d), i(q)) only requires the data (from finite element analysis or measurements) along the boundaries of the range to be mapped. To this purpose, two proper functions are defined to predict the effect of cross saturation based on the coenergy variation. The two analytical functions can be computed directly from the data acquired on the boundaries of the (i(d), i(q)) current plane depending respectively on i(d) and on i(q) values. The method is applied to predict the flux linkage maps of a synchronous reluctance machine. The results from the semi-analytical method are compared to the full finite element analysis approach and with measurements. In the last part of the paper, different saturation models, based on a limited set of simulations, are compared, showing the new proposed method's potential, against other simplified approaches for a fast mapping
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
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