133 research outputs found
Nonlinear tracking control for sensorless permanent magnet synchronous motors with uncertainties
No full textThe recent advanced solution in Marino, Tomei, and Verrelli (2013) to the tracking control problem for sensorless IMs with parameter uncertainties is translated on the basis of letter swap connections between the models of (nonsalient-pole surface) permanent magnet synchronous motors (PMSMs) and induction ones (IMs). The (stability proof-based) nonlinear adaptive position/speed tracking control for sensorless PMSMs (with simultaneous estimation of uncertain constant load torque and stator resistance), which is accordingly obtained by exploring and decoding the design paths in Marino et al. (2013) and which surprisingly represents a simple generalization of the controller in Tomei and Verrelli (2011), constitutes an innovative solution to the related open problem. Illustrative experimental results are included
La Matematica Elementare del Feedback - Introduzione ragionata a concetti e metodi della teoria dei sistemi
No full text
Electronic tongue systems for food and environmental applications = Sviluppo di sistemi lingua elettronica per applicazioni alimentari e ambientali
No full textL’attività di dottorato è stata incentrata sullo sviluppo di un sistema sensoriale artificiale basato su un array di sensori chimici potenziometrici, per la rilevazione di molecole target in matrici liquide, quali acqua potabili o reflue, vini o liquidi biologici. Il primo passo della ricerca è stato volto allo studio delle prestazioni chimiche di diversi materiali sensibili, sia di natura organica (complessi metallici di macrocicli poli-pirrolici, in particolare porfirine e corroli), sia di natura inorganica (fili metallici di diversa composizione, metalli puri o leghe). I sensori sviluppati hanno mostrato una buona sensibilità e selettività verso differenti ioni target. Dopo tali studi preliminari, diversi prototipi di sistemi di Lingua Elettronica sono stati sviluppati: in particolare questo lavoro è stato volto alla realizzazione di un micro-sistema, in cui una Lingua Elettronica miniaturizzata è stata utilizzata come detector all’uscita di una micro-colonna di separazione (all’interno del Progetto Europeo Integrato GoodFood).The Ph.D. activity has been focused on the development of artificial sensorial systems based on chemical potentiometric sensors, devoted to detect target molecules in liquid matrices, such as drinkable and waste waters, wines, human urines, etc. The first step of the research was devoted to evaluate the performances and the chemical properties of different sensing materials, both organic (metal complexes of polypyrrolic macrocycles, mainly porphyrins and corroles) and inorganic (wires of different compositions, metals or alloys). The developed sensors have shown good sensitivity and selectivity performances. After these preliminary studies, the development of different prototypes of Electronic Tongue systems has been carried out. This work has been mainly focused on the realization of a micro HPLC system where a miniaturized Electronic Tongue has been used as detector (within the European Integrated project GoodFood)
Nonlinear adaptive control for position-sensorless permanent magnet synchronous motors with uncertainties
No full textIn this paper we show that, when the rotor position is not measured in (nonsalient-pole surface) PMSMs with unknown constant load torque and stator resistance (with the rotor speed being available along with the stator currents), it is possible to guarantee exponential rotor position tracking and-mainly-regulation without resorting to persistency of excitation conditions which involve a non-definitely zero rotor speed reference. A new output feedback control is accordingly designed, which relies on a novel adaptive observer. The only price to be paid is constituted by a non-constant reference for the stator current vector d-component
Persistency of excitation and position-sensorless control of permanent magnet synchronous motors
No full textIn this brief, the exponential rotor position tracking/regulation problem for position-sensorless (nonsalient-pole surface) PMSMs with unknown constant load torque and stator resistance is addressed. The requirement of persistency of excitation conditions involving a non-definitely zero rotor speed reference is removed, owing to the design of an innovative (speed measurement-based) adaptive observer that relies on a local version of the persistency of excitation lemma and does not involve straightforward adaptations of previous ideas
NON LINEAR CONTROL DESIGN FOR INDUCTION MOTORS AND SYNCHRONOUS GENERATORS
No full textLa tesi presenta recenti sviluppi nel progetto di leggi di controllo non lineari per motori ad induzione e generatori sincroni: tecniche di controllo robuste, adattative, in retroazione dallo stato o dall'uscita sono utilizzate per tali sistemi elettromeccanici descritti da equazioni differenziali ordinarie, deterministiche e
¯nito-dimensionali e possibilmente caratterizzati da incertezze come parametri non noti (costanti o tempovarianti).
I motori ad induzione, che, grazie alla loro più semplice struttura, sono più affidabili e meno costosi di quelli a magneti permanenti, a riluttanza variabile e in corrente continua, sono difficili da controllare per diverse ragioni: le dinamiche sono intrinsecamente non lineari e multivariabile (due ingressi di controllo e due uscite da controllare) ; non tutte le variabili di stato e non tutte le uscite da controllare possono essere disponibili per la retroazione; sono presenti parametri critici incerti, come la coppia di carico, tipicamente non nota in tutti i motori elettrici e la resistenza rotorica, che può variare fino al 100 % durante il funzionamento a causa del riscaldamento del rotore. La disponibilità di potenti DSP a basso costo e i
progressi nell'elettronica di potenza hanno reso algoritmi complessi implementabili anche per motori ad induzione di media e piccola taglia, che, in tal modo, sono effettivamente in grado di sostituire i motori elettrici usati, ammesso che siano garantite alte prestazioni dinamiche ed elevata e±cienza: ciò ha motivato intensi sforzi di ricerca nel progetto di controllori non lineari per motori ad induzione.
In modo analogo, la stabilizzazione transitoria e la regolazione della tensione per sistemi di potenza sono problemi di controllo classicamente di±cili: tutti i modelli dinamici che sono stati proposti per una singola macchina connessa a un in ¯ n ite bu s mostrano una intrinseca natura non lineare e, di conseguenza, diversi punti di equilibrio stabili e instabili. Primi studi miravano alla determinazione di regioni di stabilità delle condizioni operative desiderate, via funzioni di Lyapunov, cosi da studiare l'effetto delle improvvise perturbazioni meccaniche e elettriche che possono destabilizzare il sistema e forzare il singolo generatore
ad essere disconnesso dalla rete. Il problema consiste dunque nel mantenere la velocità del generatore prossima alla velocità sincrona quando perturbazioni occorrono (stabilizzazione transitoria) e regolare la tensione di uscita al corrispondente valore di riferimento nel caso di perturbazioni costanti e permanenti (regolazione della tensione in uscita). A tal riguardo, i controllori lineari realmente impiegati, progettati sulla base di approssimazioni lineari attorno alle condizioni operative, non sono in grado di sostenere le forti perturbazioni che tipicamente occorrono nei sistemi di potenza: controllori non lineari sono di conseguenza
richiesti.
La tesi è suddivisa in due parti: la prima parte (motore ad induzione) è formata dai capitoli 2, 3 e 4, mentre la seconda parte (generatore sincrono) consiste dei capitoli 5 e 6. I capitoli 2 e 3 affrontano il problema del controllo di motori ad induzione senza sensore di velocità: l'esistenza di uno schema di controllo globale è esplorata nel capitolo 2 mentre una legge di controllo non lineare adattativa è progettata nel capitolo 3. Il capitolo 4 è dedicato al progetto di un controllore non lineare per motori ad induzione
sen so rless: uno schema di controllo in retroazione dall'uscita è proposto. I capitoli 5 e 6 concernono il problema del controllo di un generatore sincrono con incertezze nei parametri: nel capitolo 5, un controllore non lineare robusto adattativo è presentato per la stabilizzazione transitoria, mentre il capitolo 6 propone
una legge di controllo non lineare robusta adattativa che garantisce sia stabilizzazione transitoria che regolazione della tensione in uscita.The thesis incorporates recent advances in the design of nonlinear control laws for induction motors and synchronous generators: robust, adaptive, state or output feedback control techniques are used for both these electro-mechanical systems which are modelled by ¯nite dimensional, deterministic ordinary
differential equations and are possibly affected by uncertainties, such as unknown constant and time-varying parameters.
Induction motors, which, due to their simpler construction, are more reliable and less expensive than those permanent magnet, switched reluctance and d.c. motors are di±cult to control for several reasons: their dynamics are intrinsically nonlinear and multivariable (two control inputs and two outputs to be controlled); not all of the state variables and not all of the outputs to be controlled may be available for feedback; there are critical uncertain parameters such as load torque, which is typically unknown in all
electrical drives, and rotor resistance, which, due to rotor heating, may vary up to 100% during operations. The availability of low cost powerful digital signal processors and advances in power electronics made complex algorithms implementable even for medium- and small-size induction motors, which, in this way, could replace currently used motors provided that high dynamic tracking performance along with highpower efficiency are achieved: this is what motivated intense research efforts in induction motor control design.
In analogous way, transient stabilization and voltage regulation for power systems are classically difficult control problems: all the dynamic models which have been developed for a single machine connected to an in¯nite bus show an intrinsic nonlinear nature and, consequently, there are several stable and unstable equilibrium points. Early studies aimed at determining the stability regions of desired operating conditions
by means of Lyapunov functions in order to study the effect of perturbations. In fact, sudden mechanical and electrical perturbations may drive the system outside its stability region and force the generator to be disconnected from the network. The transient stabilization and voltage regulation problem consists in the design of an excitation control which keeps the generator speed close to the synchronous speed when perturbations occur (transient stabilization) and regulates the output voltage to the corresponding reference value in the case of permanent constant perturbations (voltage regulation). To this purpose, linear controllers are actually employed which are designed on the basis of linear approximations around operating conditions: only small perturbations and deviations from operating conditions can be handled. It is clear that nonlinear controllers are required to handle the large perturbations that typically occur in
power systems. The thesis is divided into two parts: Part I (induction motor) consists of Chapters 2, 3 and 4 while Part II (synchronous generator) consists of Chapters 5 and 6. Chapters 2 and 3 address the problem of controlling a speed-sensorless induction motor: the existence of a global controller is explored in Chapter
2, while a nonlinear adaptive control scheme is developed in Chapter 3. Chapter 4 is devoted to nonlinear control design for a sensorless induction motor: an output feedback control algorithm is proposed. Chapters 5 and 6 address the problem of controlling a synchronous generator with parameter uncertainty: a nonlinear robust adaptive transient stabilizing control is presented in Chapter 5, while Chapter 6 proposes a nonlinear robust adaptive transient stabilizing and output regulating control algorithm
PMSM-Model-Based Sensorless Control of Hybrid Stepper Motors: Performance and Robustness to Parameters Dispersion
No full textExtended Kalman Filters (EKFs), Phase Locked Loops (PLLs), and Stator Flux Observers (SFOs) are widely used for sensorless control of Permanent Magnet Synchronous Motors (PMSMs) drives. Their use (in their most advanced version) is here extended, on the basis of model analogies and suitably-guaranteed closed loop stability properties, to the sensorless speed regulation control of Hybrid Stepper Motors (HSMs), in which position and speed sensors are not employed to reduce costs and increase robustness with respect to high temperature and high-vibration environments. Both realistic simulations and experimental results demonstrate the feasibility of the proposed methods in terms of closed-loop performance and robustness to parameters mismatch
Stator Flux Observer for the Sensorless Speed Control of Synchronous Machines with Uncertain Torque Constant
No full textIn this paper, a recently designed adaptive stator flux observer (SFO), which provides estimates of rotor position and torque constant for surface mounted permanent magnet synchronous machines (PMSMs), is included in a speed sensorless control. Simulations and experimental results are carried out in order to evaluate the robustness of the whole control architecture with respect to uncertainties in the electrical parameters of the motor, as well as to the mismatch between the actual stator voltages imposed to the PMSM and the ones used for the observer, especially when low speeds are involved
A new Bernard–Praly-like observer for sensorless IPMSMs
No full textA slight extension of the global Bernard–Praly gradient adaptive observer – originally presented for nonsalient-pole surface Permanent Magnet Synchronous Motors (PMSMs) and recently proved to own local exponential convergence properties under well-known observability conditions – is here designed and proposed for Interior Permanent Magnet Synchronous Motors (IPMSMs) (with relatively small saliency) in the case in which the q-axis current is constant. It guarantees local exponential estimation – from stator current and voltage measurements – of both the stator fluxes and the sinusoidal/co-sinusoidal functions of the motor electrical angle, with no modification of the previous persistency of excitation condition requirements. Such an extension complements – at least locally – a previous analysis concerning IPMSMs under constant d-axis current. Applications to the sensorless control of IPMSMs (with realistic simulations) are included
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