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Design of electric motors and power drive systems according to efficiency standards
Get PDFThe focus of this article is the design of high efficiency electric motors adopted in power drive systems (PDS). The last efficiency standards are considered as constraint for the motor and drive design: they are introduced and described and their impact on the choice made during the design process are highlighted. As a particular case, the perspective of a motor manufacturer is adopted in order to understand which is the proper efficiency level of the motor required to fulfil the efficiency requirements of the PDS. This is not always clear and easy to understand because different standards apply in the two contexts. A design example of an industrial motor with 3 kW power is included, showing also experimental results on a prototypes. Also the standards related to the experimental tests, in particular those prescribing instrument accuracy, are considered and commented in the article
Progetto di motori elettrici e azionamenti per carichi centrifughi
No full textQuesto lavoro di tesi riassume le attività svolte nell’ambito del dottorato
di ricerca dell’autore. Le attività di ricerca sono state svolte
all’interno del Laboratorio di Azionamenti Elettrici (EDLab) del Dipartimento
di Ingegneria Industriale dell’Università degli Studi di
Padova, dove la maggior parte dei progetti sono svolti in collaborazione
con aziende affermate nel settore dei motori elettrici. Nella
collaborazione con le aziende le normative e gli standard assumono
un peso determinante per l’immissione nel mercato di apparecchi che
utilizzano energia elettrica, in particolare per i motori elettrici, i quali
sono i principali responsabili del consumo di energia elettrica in ambito
industriale e domestico.
Lo scopo principale di questa tesi è quello di presentare delle soluzioni
per migliorare le prestazioni energetiche di motori elettrici esistenti.
Il quadro normativo `e in continua evoluzione e impone regole stringenti
sull’efficienza minima di motori e azionamenti elettrici. La
soluzione attualmente più diffusa per applicazioni industriali e domestiche,
in particolare per macchinari centrifughi, sono i motori a
induzione con gabbia di scoiattolo in alluminio al rotore. Il limite
di questi motori sta nelle perdite di rotore, le quali rendono difficile
raggiungere quelle classi energetiche definite come ”premium”.
La soluzione proposta per superare questo limite è quello di sostituire
i motori a induzione con motori sincroni, i quali non presentano
perdite di rotore. In particolare i motori a magneti permanenti sono
i migliori candidati grazie alla loro capacità di raggiungere valori elevati
di efficienza.
Nella sostituzione dei motori a induzioni con altre tipologie di motori,
dal punto di vista delle aziende che producono motori elettrici
in serie, conviene adottare la stessa struttura meccanica dove possibile.
Ad esempio è possibile utilizzare case e geometrie di statore
standard, questo permette di ridurre i costi dei componenti e di utilizzare
le linee di montaggio esistenti. Di conseguenza in questo studio
`e progettata solo la geometria di rotore.
I motori sincroni proposti in questa tesi sono di due tipi: motori
sincroni azionati da inverter e motori sincroni auto avvianti direttamente
da rete. Nel caso di motori sincroni azionanti da inverter la
ricerca comprende anche lo sviluppo del firmware di controllo per
l’azionamento. L’algoritmo di controllo proposto è di tipo sensorless,
il quale permette di evitare l’utilizzo del sensore di posizione/velocità
con conseguente riduzione del costo e dimensioni dell’azionamento.This thesis summarizes the activities carried out as part of the author’s
PhD. The research activities were carried out within the Electric
Drive Laboratory (EDLab) of the Department of Industrial Engineering
of the University of Padova, where most of the projects are
carried out in collaboration with established companies in the field
of electric motors. In the collaboration with the companies, regulations
and standards have a decisive weight for the introduction in
the market of devices that use electrical energy, in particular for electric
motors, which are the main responsible for the consumption of
electrical energy in industrial and domestic environments.
The main purpose of this thesis is to present solutions to improve
the energy performance of existing electric motors. The regulatory
framework is constantly evolving and imposes stringent rules on
the minimum efficiency of electric motors and drives. The currently
most popular solution for industrial and civil applications, in particular
for centrifugal machinery, are induction motors with aluminium
squirrel cage. The limitation of these motors lies in the rotor losses,
which make it difficult to achieve those energy classes defined as
”premium”. The proposed solution to overcome this limitation is to
replace induction motors with synchronous motors, which do not
have rotor losses. In particular, permanent magnet motors are the
best candidates due to their ability to achieve high efficiency.
When replacing induction motors with other types of motors, from
the motor manufacturer point of view, it is better to adopt the same
mechanical structure where possible, in particular in case of series
production. For example, it is possible to use standard outer casings
and standard stator geometries, which allows to reduce component
costs and to use existing assembly lines. Consequently, only the rotor
geometry is designed in this study.
The synchronous motors proposed in this thesis are of two types:
inverter driven synchronous motors and self starting synchronous
motors directly from the grid. In the case of inverter-driven synchronous
motors, the research also includes the development of the
control firmware for the drive. The proposed control algorithm is sensorless,
which allows to avoid the use of the position/speed sensor
with consequent reduction of cost and dimensions of the drive
Case of Study of the Electrification of a Tractor: Electric Motor Performance Requirements and Design
Get PDFThe focus of this paper is the potential electrification of specialized agricultural tractors involved in vineyards and orchards. This category of machinery has not received research attention to date; however, regulations are encouraging lower emissions and higher efficiency, requiring the adoption of new technologies. Traction makes up only a limited part of this application, and the working cycle is not trivial; therefore, the design of the system is not straightforward. This study takes advantage of experimental measurements carried out under real operating conditions on a traditional specialized tractor, which was chosen as performance target. The performance requirements of the hybrid powertrain components are investigated, with particular focus placed on the electric motor. According to the dimension constraints, the design of the electric motor is carried out considering the requirements in terms of its thermal-equivalent torque and overload capability. The results are validated through a detailed thermal simulation under real duty cycles
On the efficiency requirements for electrical motors and power electronics in complete drive systems
No full textThis paper focuses on efficiency levels for low power electric drive. In particular a domestic drive with a power of 1.1 kW is considered. After a general review of the applicable standards, the different specification on the efficiency levels is presented. In particular, the perspective of a motor manufacturer is adopted in order to understand which is the proper efficiency level of the motor in order to fulfil the efficiency requirements of the complete drive system
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
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
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