1,721,278 research outputs found
Teaching Dc-Dc Switch-Mode Converter Design to Undergraduates in Power Electronics Education
No full textThis paper presents an outline of an integrated- lecture-laboratory lesson for undergraduates in power electronics. In a new university structure, where the number of hours per course is being reduced, productivity of learning must increase, in order to avoid a decrease in the quality of education. As a consequence, teachers should make every effort to present their subjects in the most interesting and appealing way possible, so as to accelerate the learning process. The example proposed consists in a typical subject for power electronic courses: DC-DC switch-mode converters. Theoretical concepts are presented in a lecture suitable for the level of the students. Since the objective is to obtain rapid and easy learning, attract the students’ attention and stimulate their interests, the lecture integrates extensive use of laboratory activities. The case of designing a multifunctional converter is briefly described, as an example of laboratory wor
On the validity of averaging techniques for nonlinear systems
No full textVibrational control is a novel technique introducing additive or multiplicative vibrations into the system parameters in order to shape suitably the response of a linear or non linear dynamical
system. Usually there are available only some theoretical results. based on averaging techniques, that assure the existence ofa suitable vibrational control. Almost no quantitative results useful from an engineering point of view are avaiilable. With reference to a particular test case, the well known Duffing equation, the performance improvement obtained by non linear vibrational control is illustrated along with a conjecture on the design parameters that is substantiated by extensive simulation results
Autotuning and Monitoring
No full textWith reference to single-input single output classical control structures, we illustrate two deterministic approaches to monitoring. On fine closed loop relay tests are proposed for monitoring performance of the controlled plant and for an on-line autotuning of the controller parameters, based on the integral of the absolute value of the error (IAE). With respect to standard formulation, a modified IAE index is used, computed from the data collected during a period of the output of the process, executing the auto-tuning test, without substantial modifications of the operating point
I controlli nel trasporto ferroviario ad alta velocità
No full textI recenti sviluppi del mercato dei trasporti, e in particolare la soluzione del trasporto su rotaia, sono sempre più presenti all'attenzione non solo delle autorità politiche ma anche dei cittadini. L'interesse al miglioramento delle prestazioni dei sistemi di trasporto in ambito sia locale sia internazionale ha trovato larga risonanza anche a livello scientifico e l'attività di ricerca universitaria ha registrato un interesse crescente. Ad esempio,il progetto nazionale "Controlli innovativi nei sistemi di trasporto ad alta velocità" ha individuato alcuni problemi chiave da risolvere per migliorare l'affidabilità del servizio ferroviario e ridurre l?eventualità di possibili disservizi. In questo articolo viene esposto un quadro delle problematiche di ricerca relative al trasporto ferroviario ad alta velocità
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
Intelligent Variable Structure Control in Electrical Drives
No full textThe variable structure approach to control synthesis leads to a systematic desugn technique realizing strong stability characteristics and high speed of response by means of simple control laws. Usually sliding modtion occurs so that the closed loop system becomes less sensitive to parameter variations and noise disturbances. These advantages are contrasted by some undesired effects due to high gain subsystems; typically chattering and control discontinuity prevent us from the implementation. In order to overcome these difficulties the variable structure control has to be modified giving rise to intelligent variable structure systems. A successful approach is obtained by replacing ideal relays by high gain elements and by fading. The dynamic performance improvements are pointed out on a high performance speed control system with PI nonlinear controllers for d.c. or brushless electrical drives
Sulla Selezione delle Variabili in un Sistema Multivariabile: da RGA a ROmA
No full textUn problema fondamentale nel controllo di un sistema multivariabile è la scelta preliminare dell’accoppiamento fra le variabili di controllo e di uscita. La tecnica più usata è la RGA, proposta da Bristol nel 1966; tale tecnica presenta notevoli limitazioni, per cui sono tate proposte numerose modifiche. Tuttavia nessuna tecnica tra quelle proposte presenta caratteristiche globalmente soddisfacenti. In questo lavoro viene presentato un approccio alternativo, che consente di considerare la dinamica del sistema in esame con semplici indicatori globali, mantenendo le caratteristiche di semplicità di uso tipiche della RGA. Le informazioni sulla dinamica dell’impianto necessarie per la costruzione del nuovo indice, denominato ROmA, possono essere rilevate con l’uso di procedure di autoscillazione, mediante classica inserzione di relé. Vengono infine presentati alcuni casi tipici, che mostrano i vantaggi dell’approccio proposto
Reciprocal root locus approach to path planning for multiple mobile robots
No full textThe path planning problem for multiple mobile robots is addressed in this study. Given the available mobile robots and the tasks to be executed, at the highest planning level a first problem is the assignment of tasks to robot or AGV, the second is path planning. In this case a quickplanning is desirable for computing feasible paths in a given workspace without congestion. The proposed solution is based on the theory of conformal transformations that can be used to map the given workspace in a more appealing geometric setting. Some examples are considered to illustrate the proposed technique and its efficienc
On Input-Output Selection for Multi-Loop Control: from RGA to ROmA
No full textA new tool for selecting the right pairing between inputs and outputs in a multiloop system is introduced. Similar in structure to the classical RGA the new array, called a Relative Omega Array, is based on the characteristic frequencies in open and closed loop under perfect control, as eventually detected by a classical relay test. This way the dynamic properties of the system are simply taken into account. Some examples show that the new tool is effective, giving the correct pairing also when the RGA approach fails
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
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