1,721,139 research outputs found
Modulating functions for modelling PWM switching converters
No full textThe aim of the work is to identify continuous average models of switching converters from input-output data. Among the various identification techniques, modulating functions were chosen due to their capability for revealing converter dynamics, even in the case of fast time constants. Due to its low-pass filtering property, such an identification technique reveals its effectiveness in the case of the evaluation of average models for switch-mode DC-DC converters. Following a brief description of the modulating functions properties, simulation and experimental examples of application are presented, first for the case of the basic boost converter and then for more complex topologies, like the half-bridge current doubler converter. The last example considers the application of such a technique to a resonant converter: a relevant result is that the technique allows an easy modelling particularly in critical cases of resonant converters where traditional averaging techniques fail
Modulating functions for testing the performance of switch-mode converters
No full textAim of the paper is to build mathematical models of DC-DC switch converters (Buck, Buck-Boost and Boost typologies) using input-output data. Among the various identification techniques, the choice of modulating function method was due to its low-pass filtering action. In plain words such feature appears a useful property for a suitable identification of average (low-pass) models at different operating points. The models proposed (including the effects of parasitic resistances) have been validated both by extensive simulations and by ex-perimental tests. An important outcome of such identification and modeling procedure is its effectiveness in performing an experimental evaluating of the loss parameters of the convert-ers: their determination is relevant for testing the efficiency of the switch-mode converte
Large signal models of ZVS class E2 resonant converters
No full textThis paper proposes a simple and systematic procedure for identifying averaged large-signal models of resonant converters. The nonlinear behaviour of the converter is modelled via Hammerstein models, i.e., the model is represented by a static nonlinearity, followed by a linear transfer function. The parameters of the approximating structure are identified from input-output noisy data, with the application of modulating functions method. PSpice simulations and experimental tests are run for an exhaustive and accurate validation of the proposed methodology. A relevant result is that the technique allows an easy modelling in the critical case of resonant converters, where traditional averaging techniques fail
Procedure automatiche di autosintonia per modelli Hammerstein-Wiener
No full textIn questo lavoro vengono introdotte delle estensioni alla procedura di identificazione detta nonlinear auto-tune variation (Natv) proposta originariamente da Luyben e Eskinat. La tecnica è ben nota dalla letteratura, ma è essenzialmente del tipo trial and error per quanto riguarda la simmetrizzazione del relay. Di seguito viene presentata una soluzione che automatizza completamente il processo di autosintonia sia nel caso di sistemi di tipo Hammerstein che Wiener
Diagnostica non convenzionale per azionamenti elettrici
No full textVengono presentate alcune tecniche di diagnostica basate su modelli parametrici e non. Le tecniche possono essere impiegate per applicazioni in tempo reale: La prima è basata sull'impiego delle funzioni modulanti in forma ricorsiva, la seconda su tecniche di adattamento col metodo del gradiente. Vengono illustrate alcune applicazioni nel caso di un motore brushless sinusoidale (PMSM) e di un motore in continua a magneti permanenti
Didactic Considerations on Magnetic Circuits Excited by Permanent Magnets
No full textIn this paper, the authors focus their attention on the way magnetic circuits and permanent magnets are usually treated in most textbooks and electrical engineering courses. This paper demonstrates how this important topic is too often presented sim- plistically. This simplistic treatment does not allow the students to develop a complete understanding of the problem, and it leads to a misinterpretation of the sometimes wrong results obtained by using the most common formulas. A guideline and a set of exam- ples, which could help the students to a better understanding of the topic, are presented here
DATV per l’autosintonia di regolatori PID
No full textSi illustra l’impiego di una tecnica di autosintonia per regolatori standard, basata sulla stima del guadagno critico e dell’oscillazione critica, attraverso una tecnica a relè con dither, detta Datv. Rispetto alle tecniche tipiche per l’autosintonia, la Datv permette di stimare i parametri critici con notevole precisione, pur mantenendo caratteristiche di semplicità realizzativa e insensibilità al rumore, che ne suggeriscono l’uso nel caso di processi con amplificatori Pwm e/o attuatori a relè
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