1,721,104 research outputs found
Electrical drives for application in mechatronics - Azionamenti elettrici per la meccatronica
No full textThis thesis is the result of a three-years work at the Department of Technique and Management of Industrial Systems of the University of Padova, located in Vicenza, Italy.
The research concerns advanced control methodologies for electrical drives. In particular, the first part of the thesis deals with sensorless control of induction motors, in which the speed is not measured but estimated by means of a mathematical model. Among the topics, there is a corollary of the sensorless control: the compensation of PWM inverter non-linearities and the induction motor parameters estimation.
The second part of the thesis deals with a strategy for the automatic seeking of the maximum torque-per-ampere ratio in synchronous reluctance motors, with extension of the theory (and practice) to other motor types. The study aims to the development of more energy-efficient controls in which motor losses are reduced with the convenient choice of the control variables.Questa tesi è frutto dei tre anni di lavoro svolto presso il Dipartimento di Tecnica e Gestione dei Sistemi Industriali dell’Università degli Studi di Padova, sito in Vicenza, Italia. Il principale filone di ricerca trattato riguarda le metodologie di controllo avanzate per azionamenti elettrici. In particolare, nella prima parte della tesi sono stati trattati i controlli sensorless per motori ad induzione, in cui la velocità del motore non è misurata ma è stimata con un modello matematico. Due degli argomenti riportati ne costituiscono un naturale corollario: la compensazione delle non linearità negli inverter PWM e la
stima parametrica per motori ad induzione.
La seconda parte della tesi tratta una strategia per la ricerca automatica del massimo rapporto coppia/corrente per motori sincroni a riluttanza, con estensione della teoria (e della pratica) ad altri tipi di motori. Lo studio è volto allo sviluppo di controlli più efficienti in cui le perdite del motore siano ridotte tramite opportune scelte delle variabili di controllo
The Diplomatic Promotion of Italian Cinema in English-Speaking Countries
No full textIn our paper we analyse the distribution and promotion of Italian films in English-speaking countries, using as privileged point of observation that of the Istituti italiani di cultura all'estero (Italian Cultural Institutes). We interviewed a number of them and other agencies or individuals that regularly screen and organize screenings of Italian films. We conclude that chance, special occasions, and random choices seem to drive much of this kind of distribution of Italian films in the Anglophone countries, a conclusion that is not a value judgement but rather an observation. We also note how a certain realist tendency of Italian cinema seems to be still accepted and promoted, as are social and political themes, in part thanks to many documentaries that do not always get distributed in Italy but that are often screened abroad. Finally, we hope this preliminary research will soon be complemented by other research of this kind, possibly in collaboration with scholars from other disciplines ranging from cultural economics to the sociology of organizations
Non-Theatrical Circuits of Italian Cinema in the American Midwest. A Case Study
No full textThis paper aims to investigate the presence of Italian cinema in non-theatrical circulation circuits in the United States. We compare two different patterns of dissemination of Italian culture during the last decade: on the one hand, the role of contemporary Italian cinema in several film festivals; on the other, the screenings, events and retrospective organized by a series of cultural centers. In the first part, we will provide a quantitative overview on the presence of non-theatrical circulation of Italian cinema abroad, with specific references to the United States, such as Italian cinema in U.S. film festivals and an overview of festivals specifically related to Italian cinema. We will compare this data to the numbers of screenings and retrospectives organized both by Italian cultural institutes and cultural venues in the U.S. during the last decade. In a second part, we will focus on two specific case studies in the American Midwest: the Italian Film Festival USA and the Wexner Center for the Arts in Columbus (Ohio). In the first case, we will trace the paths of what the Festival director Barbara Klein calls a “cinematic tour of Italy”: a touring festival that takes place every year in April across various cities of the Midwest and beyond, from Cleveland to Indianapolis. In the second case, we will discuss the cultural and social role of Italian cinema in the film programming of the Wexner Center for the Arts, the most important cultural hub of the area, located the Ohio State University campus in Columbus. Our sources are schedules, programs, and interviews with cultural professionals, as well as articles referring to these initiatives published in the local press. Taking these examples as a paradigm, we try to understand how these two different types of circulation influence the narrative patterns and the transnational reception of Italian culture storytelling abroad
Design Comparison of Outer- and Inner-Rotor Permanent Magnet Motors for Hydrofoil Boat
Full text linkThis paper presents the design criteria of a permanent magnet motor for hydrofoil boat applications. Based on the dynamic analysis of hydrofoil boat, the constraints of propulsion motor are derived and therefore the surface-mounted permanent magnet motor is chosen as the competitive candidate. In order to have large power density in the permanent magnet motor, the outer- and inner-rotor motors are investigated and compared to demonstrate their advantages at different design constraints, which will provide the theoretical basis to improve the propulsion system in the hydrofoil boat from the perspective of motor design
The Scalable Analytical Model for Calculating the Magnetic Field of Surface-Mounted Permanent Magnet Motor
Full text linkThis article develops a scalable analytical model that builds a relationship between any surface-mounted permanent magnet (SPM) motor and a general motor with variable slot-opening and air-gap length, considering both the saturation effect and slotting effect. It can not only give the performance of the single SPM motor but also show internal connection among different SPM motors regardless of the motor power and dimension. To account for the iron saturation, the equivalent saturation current combined with simplified BH curves of iron is introduced to directly present the iron magnetic potential distribution without an iterative process. Thus, the proposed model can be used as the surrogate model in the motor design with little computation and provide great insight into the relationship among motors with different power and dimension. Both finite-element analysis and experiment are carried out to validate the proposed model.QC 20250122</p
Parameter sensitivity analysis of an improved open-loop speed estimate for induction motor drives
No full textThe paper presents a detailed sensitivity analysis comparison between two existing low-cost sensorless solutions for induction motor drives. The first solution is a V-type approach, in which the inverter voltage references are calculated from the machine equations instead of obtained as the output of PI current regulators. The scheme is obtained from a standard field oriented control drive by successive approximations. The second solution is an open- loop speed estimator, based on the machine equations only, used in conjunction with a field oriented control drive with speed and current closed loops. An analytical sensitivity analysis has been carried out first, looking for the behaviour of the two schemes in presence of single motor parameter mismatch. Both schemes have been implemented in laboratory prototypes, and their performances have been tested in different conditions. The results of the comparison are discussed in details. A side value is the generality of the proposed analysis method, which can be applied as a standard comparison tool for control schemes evaluation
Repetitive-control-based self-commissioning procedure for inverter nonidealities compensation
No full textHigh-performance sensorless ac drives require the exact knowledge of the motor phase voltages in the whole speed range. The use of voltage sensors may be eschewed if the reference voltage signals, generated by the control algorithm, can be used instead. To this aim, an accurate compensation of most of inverter nonidealities is essential. This paper presents a novel self-commissioning procedure for the cancellation of inverter nonidealities, based on repetitive control. The main advantage is that the compensation generated by the procedure automatically includes the insulated-gate bipolar transistor parasitic effects during current zero-crossing, whose exact knowledge is one of the major problems in most of the standard dead-time cancellation techniques. Despite its elaborated theoretical background, the method requires few computational resources, and it is easy to implement. Mathematical developments, design hints, and an extensive batch of successful experimental tests are included in this paper
Self-commissioning calculation of dynamic models for synchronous machines with magnetic saturation using flux as state variable
Full text linkThis paper deals with the non-linear modelling of synchronous machines by using the flux linkage as a state variable.The model is inferred from a conventional set of measurements where the relation between the currents and the flux linkages inthe rotating reference frame (also known as dq reference frame) are known by measurements or estimated through finite-element simulations. In particular, the contribution of this paper is twofold: first, it proposes a method to extract the non-linearmodel information which can be easily implemented in electric drives, without the need of offline post-processing of the data.Second, it mathematically demonstrates that the method converges to the final result in a stable way. An example based onexperimental measurements of the current-to-flux look-up tables of an 11-kW synchronous reluctance machine is shown,proving the feasibility of the proposed method.QC 20190513</p
Equivalent Resistance Model of the Permanent-Magnet Motor for Predicting Electromagnetic Losses
No full textThis paper proposes an equivalent resistance model of the permanent-magnet (PM) motor which is useful for predicting the losses. The PM loss and iron loss are replaced by the eddy-current loss and hysteresis loss in the equivalent resistance model, where the characteristics of these losses are extracted from the analytical model. The harmonic current and the current control angle are investigated in the paper to guarantee the accuracy of the loss prediction. The parameters in the equivalent resistance model can be easily obtained from the finite-element model and experiment. The proposed model demonstrates significant potential to improve motor efficiency.</p
Introduzione (a Media-Impresa. Discorsi e pratiche cinematografiche e mediali nella cultura industriale)
No full textDelle tante vite parallele del cinema quella industriale non è certo tra le
più appariscenti. Eppure, è anche districandosi fra cubicoli da ufficio, fiere campionarie, presentazioni aziendali e viaggi d’affari che i mezzi audiovisivi hanno adempito alla propria funzione di agenti storici, divenendo presenze via via più pervasive e influenti nella quotidianità dei luoghi di lavoro. Questo numero speciale di «Cinema e Storia» parte dall’ormai vasta letteratura esistente sul cinema industriale e sponsorizzato per adottare una più ampia prospettiva sul processo di “mediatizzazione” che ha interessato le imprese e le organizzazioni lavorative nel contesto italiano. Muovendo della ripresa post- bellica come punto di partenza obbligato e individuando il boom economico quale periodo di maggior fortuna della cinematografia d’impresa, ci si spinge fino a metà degli anni Ottanta, quanto la rete mediale delle aziende accoglie l’introduzione delle tecnologie elettroniche e informatiche. A diverse altezze
di questo percorso, i saggi qui raccolti offrono spaccati sulle istituzioni e sui saperi che hanno contribuito a irregimentare il cinema tra gli strumenti della cultura imprenditoriale, sulle accezioni discorsive di medialità che emergono dalle pagine degli house organ aziendali e sul ruolo giocato dall’audiovisivo nella rappresentazione dei paesaggi industriali e nella costruzione della corporate image. Un assortimento di casi differenti sui quali si staglia il miraggio tutto italiano del tecno-umanesimo, ora in termini utopistici (il perfetto connubio fra estro artistico e precisione tecnica) ora con sembianze distopiche, a piegare ogni espressione culturale ai fini dell’ingegneria sociale
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