Dissertations / Theses on the topic 'Macchine innovative'

The dynamics of a passive back-to-back test rig have been characterised, leading to a multi-coordinate approach for the analysis of arbitrary test configurations. Universal joints have been introduced into a typical pre-loaded back-to-back system in order to produce an oscillating torsional moment in a test specimen. Two different arrangements have been investigated using a frequency-based sub-structuring approach: the receptance method. A numerical model has been developed in accordance with this theory, allowing interconnection of systems with two-coordinates and closed multi-loop schemes. The model calculates the receptance functions and modal and deflected shapes of a general system. Closed form expressions of the following individual elements have been developed: a servomotor, damped continuous shaft and a universal joint. Numerical results for specific cases have been compared with published data in literature and experimental measurements undertaken in the present work. Due to the complexity of the universal joint and its oscillating dynamic effects, a more detailed analysis of this component has been developed. Two models have been presented. The first represents the joint as two inertias connected by a massless cross-piece. The second, derived by the dynamic analysis of a spherical four-link mechanism, considers the contribution of the floating element and its gyroscopic effects. An investigation into non-linear behaviour has led to a time domain model that utilises the Runge-Kutta fourth order method for resolution of the dynamic equations. It has been demonstrated that the torsional receptances of a universal joint, derived using the simple model, result in representation of the joint as an equivalent variable inertia. In order to verify the model, a test rig has been built and experimental validation undertaken. The variable inertia of a universal joint has lead to a novel application of the component as a passive device for the balancing of inertia variations in slider-crank mechanisms.

This work resumes a wide variety of research activities carried out with the main objective of increasing the efficiency and reducing the fuel consumption of Gasoline Direct Injection engines, especially under high loads. For this purpose, two main innovative technologies have been studied, Water Injection and Low-Pressure Exhaust Gas Recirculation, which help to reduce the temperature of the gases inside the combustion chamber and thus mitigate knock, being this one of the main limiting factors for the efficiency of modern downsized engines that operate at high specific power. A prototypal Port Water Injection system was developed and extensive experimental work has been carried out, initially to identify the benefits and limitations of this technology. This led to the subsequent development and testing of a combustion controller, which has been implemented on a Rapid Control Prototyping environment, capable of managing water injection to achieve knock mitigation and a more efficient combustion phase. Regarding Low-Pressure Exhaust Gas Recirculation, a commercial engine that was already equipped with this technology was used to carry out experimental work in a similar fashion to that of water injection. Another prototypal water injection system has been mounted to this second engine, to be able to test both technologies, at first separately to compare them on equal conditions, and secondly together in the search of a possible synergy. Additionally, based on experimental data from several engines that have been tested during this study, including both GDI and GCI engines, a real-time model (or virtual sensor) for the estimation of the maximum in-cylinder pressure has been developed and validated. This parameter is of vital importance to determine the speed at which damage occurs on the engine components, and therefore to extract the maximum performance without inducing permanent damages.

This thesis collects some of the work accomplished during the PhD research activity focused on the study of special electric machines for vehicle traction applications. The work is divided into due parts. The rst part is mainly technological and covers some studies and experimental activities concerning new technical solutions to solve some common issues in operation of electric motors for automotive use, namely ux weakening and cogging torque. The second part has a more theoretical nature and focuses on some methods for electric machine modeling and analysis which has been developed to facilitate the study and design optimizations carried out during the PhD research work. The chapters in the rst part address the following topics: 1. Development and testing of an interior-permanent-magnet motor prototype fully conceived, designed and manufactured at the University of Trieste to implement a new concept of flux weakening system at high speeds. The concept has been also protected through a pending patent. 2. Multi-objective design optimization of an interior permanent magnet reluctance-assisted synchronous motor for the automotive industry. The design optimization was meant to support an industrial development project which is still in progress so no prototype has been built yet. 3. Study of a new optimized magnetic wedge design capable of reducing cogging torque in automotive propulsion motors having open stator slots. The second part proposes some analytical and numerical results that have been worked out to approach the modeling and optimization of various kinds of permanent magnet synchronous motors. The main problem to which these chapters try to answer is to nd suciently fast but accurate methods for permanent magnet analysis without time-consuming finite-element transient analysis. The proposed methods have been successfully integrated into design optimization programs used in the industrial environment in the development of innovative electric machines not only for the automotive industry.<br>Questa tesi contiene alcuni dei temi riguardanti le macchine elettriche per trazione veicolare che si sono arontati durante i tre anni di dottorato di ricerca. Il lavoro è suddiviso in due parti. La prima parte si concentra su aspetti tecnologici e riguarda alcuni studi ed attività sperimentali che vanno a risolvere alcune problematiche comuni delle macchine elettriche per trazione, in particolare il deflussaggio e le pulsazioni di coppia. La seconda parte, invece risulta essere più teorica e si concentra su alcuni metodi matematici di modellizzazione ed analisi sviluppati per facilitare la progettazione e lo studio delle macchine elettriche che si è portato avanti durante il periodo di dottorato. I capitoli della prima parte sono così suddivisi: 1. Sviluppo e sperimentazione di un motore a magneti permanenti prototipale; interamente concepito, progettato e realizzato presso l'Università degli Studi di Trieste; in cui un nuovo metodo di deflussagio per alte velocità è stato implementato. Inoltre tale tecnologia è stata assoggettata a brevetto. 2. Ottimizzazione multi obiettivo di un motore sincrono a magneti permanenti a riluttanza assistita per applicazioni nell'industria automobilistica. L'ottimizzazione aveva lo scopo di supportare un progetto industrale portato avanti da un nostro partner ed ancora in atto, di conseguenza nessun prototipo è ancora stato realizzato. 3. Studio e ottimizzazione di una bietta magnetica per motori con statore a cave aperte, in grado di ridurre la pulsazione di coppia. La seconda parte propone dei metodi di analisi numerica delle macchine elettriche sviluppati per modellizzare ed analizzare diversi tipi di macchine a magneti permanenti. La principale criticità alla quale questi capitoli tentano di dare soluzione è quello di trovare dei metodi di analisi delle macchine a magneti permanenti accurati, senza dover ricorrere a simulazioni transitorie agli elementi niti, che come è noto sono molto dispendiose in termini di tempo.

2009 - 2010<br>The here considered SHM procedure concerns innovative techniques for a structural monitoring of aeronautical components, all of them based upon the use of a Scanning Laser Doppler Vibrometer. The vibrometer is used to detect the dynamic response of the component under test, in wave propagation regime. The signal so recorded consists of space and time maps of vibration velocity offplane. The purpose of the study lies in the analysis of such maps, using filtering techniques that separate reflected waves from the incident ones, so that they can enable to identify defects. The innovative application of a novel technique (introduced by Ruzzene) for the first time to stringerized composite specimens, allowed the generation of baseline information directly from the measured dataset. The effectiveness of these methods has been demonstrated through their application to detection of a delamination in a composite stiffened plate and detection of defect/wrinkling in a T-shaped skin to stringer component. The most significant technological innovations achieved through these theses are: • The option key to excite the surface of a complex structure (in this case, the skins of a composite stingerized panel) and to derive the velocity profile on surfaces orthogonal to the excited one (in our case the web of the stringer) has been checked. This is crucial, as it would allow to install the piezo elements on the stringers, to excite them and to read velocities of points over the entire surface of the skin, without disassembly. Up to now, only cases of standard solicitation have been analyzed in literature, or cases where the velocities were acquired on the same surfaces excited. Today, therefore, there is no published study on the analysis conducted in such a manner. • The damage index was also applied to stiffened and greatly complex geometries. Up to now, in literature only analysis applied to simple flat panels can be found. • The FEM simulation was carried out on stiffened panels. In literature there are only simulations carried out on simple structural elements like flat panels without any stiffener. [edited by author]<br>IX n.s.

Today, the contribution of the transportation sector on greenhouse gases is evident. The fast consumption of fossil fuels and its impact on the environment has given a strong impetus to the development of vehicles with better fuel economy. Hybrid electric vehicles fit into this context with different targets, starting from the reduction of emissions and fuel consumption, but also for performance and comfort enhancement. Vehicles exist with various missions; super sport cars usually aim to reach peak performance and to guarantee a great driving experience to the driver, but great attention must also be paid to fuel consumption. According to the vehicle mission, hybrid vehicles can differ in the powertrain configuration and the choice of the energy storage system. Lamborghini has recently invested in the development of hybrid super sport cars, due to performance and comfort reasons, with the possibility to reduce fuel consumption. This research activity has been conducted as a joint collaboration between the University of Bologna and the sportscar manufacturer, to analyze the impact of innovative energy storage solutions on the hybrid vehicle performance. Capacitors have been studied and modeled to analyze the pros and cons of such solution with respect to batteries. To this aim, a full simulation environment has been developed and validated to provide a concept design tool capable of precise results and able to foresee the longitudinal performance on regulated emission cycles and real driving conditions, with a focus on fuel consumption. In addition, the target of the research activity is to deepen the study of hybrid electric super sports cars in the concept development phase, focusing on defining the control strategies and the energy storage system’s technology that best suits the needs of the vehicles. This dissertation covers the key steps that have been carried out in the research project.

In recent decades, the use of power converters has become very popular in the field of electric drives. Several control techniques have been proposed for power converters and every year, the ongoing research and the always more powerful microprocessors, lead to new high performance solutions. Despite this, since the output of the worldwide research often results in complex and hardly applicable solutions, other well-established techniques, such as linear and hysteresis control with pulsewidth modulation, are still the main choice in a great number of industrial applications. The reasons of their leadership can be found considering the characteristics of these methods: on one side simplicity of comprehension and implementation and, on the other, sufficiently good performance and robustness. Due to these relevant features, despite there is still extensive room for improvements, it is not painless to propose solutions that can be attractive for people working in industry to compete with, and possibly to replace, traditional methods. Desirably, a control algorithm for electric drives has to be simple and easily understandable. Besides, it has to be suitable for real-time applications. Robustness and reliability, beyond that performance, have to be guaranteed since the nature of the different applications, e.g. home appliances and automotive. In this perspective, Predictive Control could represent a candidate to introduce improvements and gains in the aforementioned industrial applications. Predictive control is a wide class of controllers that uses the model of the system for the prediction of the future behavior of the controlled variables. This information is used by the regulator in order to obtain the optimal actuation, according to a predefined optimization criterion represented by a cost function. This control techique is based on concepts that are extremely simple and intuitive and besides, depending on the type of predictive control, the implementation can also be simple. In parcticular, Finite Control Set allows considering the discrete nature of the power converter and results in an extremely simple implementation. Beyond simplicity, other advantages can be recognized. First, with predictive control it is possible to avoid the cascaded structure obtaining a very fast transient response. Besides, nonlinearities can be included in the model avoiding the need of linearizing the model for a given operating point and improving the operation of the system for all conditions. Finally, it is possible to include limitations of the variables when designing the regulator. The aim of this thesis is to study Predictive Control applied to the current control of synchronous reluctance machines, analysing and addressing some open research topics regarding this kind of control. In particular, two main aspects are studied, namely the need of a precise knowledge of the machine model and the possibility to drive a synchronous reluctance machine along the Maximum Torque per Ampere, the Flux Weakening and the Maximum Torque per Voltage operations. The performance are strictly related to the accuracy of the model used for the prediction. In case of parameters mismatch or variation, rather than other model inadequacies, the prediction could be affected causing a worsening of the overall behaviour of the drive. The first part of this work is commited to study this aspect, analysing the effects of mismatches and variations focusing in particular on the detrimental effects of iron saturation. A novel model-free solution is presented to overcome the limitations given by an inadequate model. This method allows achieving good reference tracking and limited current ripple in every working condition. Besides, it presents great advantages in terms of simplicity: no additional hardware and no complicated calculations are required. The design is effortless since there are no gains, thresholds and so on, that have to be tuned. This technique could be used to develop an universal drive, meaning that completely different machines could be controlled with exactely the same algorithm, without self commissioning or identification procedures. Thanks to the aforementioned features, this techique could allow the spread of predictive control in industrial applications. In order to fully exploit the characteristics of the drive while assuring the lowest power losses in every working condition, a proper control algorithm has to be used. In the second part of this work, a predictive regulator able to track the most suitable trajectory depending on the machine operation is presented. In particular, the Maximum Torque per Ampere, the Flux Weakening and the Maximum Torque per Voltage trajectories are considered. The proposal is a combination of predictive control and hysteresis control, since its aim is to keep the current error within a certain hysteresis band, and it allows combining the benefits of the two control techniques. This study is carried out considering Predictive Current Control for Synchronous Reluctance machines. This kind of machine has been considered since it is of great interest due to the fact that it features high power density, superior reliability, high efficiency and it is cost effective due to the absence of permanent magnets and circuits in the rotor. Besides, since its significant iron saturation, its control represents a challenge (in particular) for predictive control schemes and for this reason it is a perfect case study.<br>Negli ultimi anni, l'utilizzo di convertitori di potenza in applicazioni di azionamenti elettrici è diventato molto diffuso. Diverse tecniche di controllo per convertitori di potenza sono state proposte e ogni anno, i risultati della ricerca e gli sviluppi di microprocessori consentono di raggiungere performance sempre maggiori. Nonostante ciò, poichè gli output della ricerca sono spesso soluzioni complesse e di difficile implementazione, le soluzioni più usate in ambito industriale rimangono quelle ormai consolidate, come il controllo lineare ed il controllo ad isteresi. Un algoritmo di controllo per un azionamento elettrico dovrebbe essere semplice e di facile compresione. Inoltre dev'essere adatto ad applicazioni real-time. Robustezza ed affidabilità, oltre che alle performance, devono essere garantite, in particolare in applicazioni come gli elettrodomestici e l'automotive. Alla luce di ciò, il Controllo Predittivo rappresenta un valido candidato per introdurre vantaggi e miglioramenti in ambito industriale. Questa tecnica di controllo sfrutta un modello del sistema per predire il comportamento futuro delle variabili controllate. Questa informazione è utilizzata per scegliere l'azione di controllo migliore in base ad un criterio di ottimalità predefinito. Questo tipo di controllo è basato su idee che sono concettualmente semplici e intuitivi. Inoltre, l'implementazione della versione Finite Set risulta particolarmente facile. Oltre alla semplicitò gli altri vantaggi sono la possibilità di evitare la struttura in cascata (tipica del controllo lineare), le nonlinearità e le limitazioni possono essere direttamente incluse nel modello. Lo scopo di questa tesi è di studiare il controllo predittivo applicato al controllo di corrente di una macchina Sincrona a Riluttanza, analizzando ed affrontando alcune tematiche ancora aperte. In particolare, due aspetti sono considerati: la necessità di conoscere in modo preciso il modello della macchina e la possibilità di controllare la macchina lungo le traiettorie di MTPA, Flux-Weakening e MTPV.

Fatigue damage due to random load: numerical, experimental and design an innovative testing machine<br>Fatigue damage due to random load: numerical, experimental and design an innovative testing machine

Although Hybrid Electric Vehicles (HEVs) represent a powerful technology to save fuel and reduce pollutant emissions, through the synergic use of a conventional internal combustion engine and one or more electric machines, their performance strongly depends on the control strategy that defines the operating mode and shares the power demand among the different power actuators at each time instant. Con-sequently the aim of this work is the definition of a comprehensive methodology to develop, through numerical simulation, a sub-optimal hybrid powertrain control strategy: two specific hybrid architectures will be taken into account as test cases in order to highlight the effectiveness of the proposed methodology. Starting from the problem formulation, the ideal performance of the vehicles will be analyzed through a global optimization algorithm in order to point out information which can be used to define new control laws. Coupling these information with an ap-proach based on the instantaneous minimization of a cost function, a sub-optimal energy management system will then be developed trying to merge the strength of global optimization algorithm with the low computational requirement of heuristic strategies. Finally the performance of the proposed energy management system will be integrated into detailed vehicle models and tested in typical driving conditions.

The thesis work deals with topics that led to the development of innovative control-oriented models and control algorithms for modern gasoline engines. Knock in boosted spark ignition engines is the widest topic discussed in this document because it remains one of the most limiting factors for maximizing combustion efficiency in this kind of engine. First chapter is thus focused on knock and a wide literature review is proposed to summarize the preliminary knowledge that even represents the background and the reference for discussed activities. Most relevant results achieved during PhD course in the field of knock modelling and control are then presented, describing every control-oriented model that led to the development of an adaptive model-based combustion control system. The complete controller has been developed in the context of the collaboration with Ferrari GT and it allowed to completely redefine the knock intensity evaluation as well as the combustion phase control. The second chapter is focused on the activity related to a prototyping Port Water Injection system that has been developed and tested on a turbocharged spark ignition engine, within the collaboration with Magneti Marelli. Such system and the effects of injected water on the combustion process were then modeled in a 1-D simulation environment (GT Power). Third chapter shows the development and validation of a control-oriented model for the real-time calculation of exhaust gas temperature that represents another important limitation to the performance increase in modern boosted engines. Indeed, modelling of exhaust gas temperature and thermocouple behavior are themes that play a key role in the optimization of combustion and catalyst efficiency.

Natural gas is a promising alternative fuel for internal combustion engines application due to its low carbon content and high knock resistance. The work presented in this thesis deals with the fluid dynamics, experimental study and optimization of different technologies aimed at exploiting the potentials of such fuel at best. The first section of the work is aimed at the combustion chamber optimization with the focus on the combustion stability. The engine considered in the study is a prototype specifically dedicated to CNG. It features a variable valve actuation system and has been released with different and very high compression ratios ranging from 12 to 14. An innovative experimental methodology based on hot wire anemometry (HWA) purposely developed by Centro Ricerche Fiat (CRF) has been adopted for the characterization of the steady-state tumble. The HWA method has been validated against the well-known Ricardo method and is used as a basis for the development and validation of a numerical “virtual flow bench”. The numerical model has been used to gain a deeper insight into the fluid dynamic phenomena and to replace the experimental campaign considering a head variant and quantifying its tumbling and volumetric performances. A transient 3D CFD analysis for the complete engine cycle has been performed in order to evaluate the effect on the combustion process of different compression ratios and head designs.The results showed that the HWA technique represents a factual alternative to the integral technique for the tumble characterization. The “Virtual flow box” model turned out to be accurate enough to evaluate the main flow motions induced by the head design and to be a valid tool complementary to the experimental method. Finally, the transient model used in combination with the ECFM-3z combustion model is fairly accurate for the comparative analysis between different engine designs and/or valve actuations. Despite the main findings of the flow model activity, importance should also be placed onto advanced technologies for natural gas engines such as direct injection. Thus, the second section is aimed at the numerical study of a natural gas direct injection engine. The numerical complexity caused by the high pressure ratio at nozzle exit has been faced using an accurate mesh procedure able to correctly capture the formation of shocks structures. Moreover, the actual needle geometry and the realistic needle movement has been taken into account in order to correctly simulate the opening and closing transient. The final mix and turbulence level has been evaluated comparing two engine prototypes and considering several injection strategies. Finally, a qualitative validation of the computational model has been performed comparing the simulation results with the available experimental data obtained through the PLIF procedure on an equivalent optical engine. The CFD model resulted to be accurate in the prediction of the mixing quality and it shows to be a reliable tool for the analysis of the main mixing mechanism and so for the assessment of the best injection strategy.

The use of permanent magnet synchronous machines (PMSMs) is becoming more popular [ 1 ] thanks to their compactness, high torque density and increased flux weakening performance [ 2 ]. Other advantages can be gained by equipping PMSM with concentrated winding in the stator. In fact, using concentrated winding can be beneficial regarding easy manufacturing and consequently lower production costs, modularity [ 3 ] and fault tolerance. More Fractional-Slot Concentrated Winding (FSCW) is an increasingly attractive option for the stator winding of synchronous permanent-magnet machines. Despite of the extensive studies conducted so far, there seem to be further interesting margins for expanding and improving such technology. A well-known drawback of their adoption is the occurrence of large magneto-motive force (MMF) harmonics, which produce eddycurrent losses in rotor permanent magnets. Moreover, it is commonly assumed in the existing literature that a symmetrical three-phase FSCW is feasible only on condition that the number of slots Z is an integer multiple of 3 times the maximum common divisor between Z and the number of pole pairs p. This thesis is intended to optimize the multi-layer winding design through a new general systematic methodology having the form of a multi-objective quadratic programming problem. The use of a multilayer design, with coils of different phases wound around the same tooth, is a possible countermeasure to mitigate problems as large magneto-motive force (MMF) harmonics, which produce eddy-current losses in rotor permanent magnets. In addition, this thesis explores the possibility to synthetize a symmetrical FSCWs having unconventional slot-pole combinations, i.e., with a number of slots and a number of poles that are commonly believed incompatible. It is shown that a multi-layer FSCW with (theoretically) arbitrary slot-pole combinations can be implemented and a methodology to synthetize it optimally is given. The performance of FSCW designs with conventional and unconventional pole-slot combinations is comparatively assessed. A study case is provided to illustrate the possible practical advantage of choosing an unconventional pole-slot combination.<br>Fractional-Slot Concentrated Winding (FSCW) is an increasingly attractive option for the stator winding of synchronous permanent-magnet machines. Despite of the extensive studies conducted so far, there seem to be further interesting margins for expanding and improving such technology. A well-known drawback of their adoption is the occurrence of large magneto-motive force (MMF) harmonics, which produce eddycurrent losses in rotor permanent magnets. Moreover, it is commonly assumed in the existing literature that a symmetrical three-phase FSCW is feasible only on condition that the number of slots Z is an integer multiple of 3 times the maximum common divisor between Z and the number of pole pairs p. This thesis is intended to optimize the multi-layer winding design through a new general systematic methodology having the form of a multi-objective quadratic programming problem. The use of a multilayer design, with coils of different phases wound around the same tooth, is a possible countermeasure to mitigate problems as large magneto-motive force (MMF) harmonics, which produce eddy-current losses in rotor permanent magnets. In addition, this thesis explores the possibility to synthetize a symmetrical FSCWs having unconventional slot-pole combinations, i.e., with a number of slots and a number of poles that are commonly believed incompatible. It is shown that a multi-layer FSCW with (theoretically) arbitrary slot-pole combinations can be implemented and a methodology to synthetize it optimally is given. The performance of FSCW designs with conventional and unconventional pole-slot combinations is comparatively assessed. A study case is provided to illustrate the possible practical advantage of choosing an unconventional pole-slot combination.

L’attività di ricerca qui presentata ha avuto come oggetto lo studio di soluzioni innovative per espandere le potenzialità dei rivelatori basati sulla camera a deriva di silicio (SDD) destinati in particolare all’uso sulle linee di luce presenti nelle macchine acceleratrici di terza e quarta generazione. Le camere a deriva sono strumenti oramai consolidati e comunemente usati negli esperimenti di fluorescenza a raggi X con ottime prestazioni per quanto riguarda la risoluzione energetica ma con alcune limitazioni che incidono in particolare sul tasso massimo dei conteggi rilevabili e gestibili dagli strumenti. In questo lavoro, dopo una breve introduzione al contesto e alle tecnologie attualmente disponibili per quanto riguarda i SDD, sono riportati e discussi alcuni nuovi approcci introdotti sia per aumentare l’angolo solido coperto dai rivelatori sia per gestire alti tassi di conteggio, il tutto corredato dai risultati più significativi ottenuti dalle numerose prove sperimentali con prototipi appositamente sviluppati.

Solid particle ingestion is one of the principal degradation mechanisms in the compressor section of heavy-duty gas turbines. Usually, foulants in the ppm range not captured by the air filtration system cause deposits on blading and result in a severe performance drop of the compressor. It is of great interest to the manufacturer and industry to determine which areas of the compressor airfoils are affected by these contaminants as a function of the location of the power unit. The aim of this work is the estimation of the actual deposits on the blade surface in terms of location and quantity. Particle trajectory simulations use a stochastic Lagrangian tracking method which solves the equations of motion separately from the continuous phase. Then, a transonic rotor and subsonic rotor are considered as a case study for the numerical investigation. The compressor rotor numerical model and the discrete phase treatment have been validated against the experimental and numerical data available in literature. The size of the particles, their concentrations and the filtration efficiency are specified in order to perform a realistic quantitative analysis of the fouling phenomena in an axial compressor. This study combines the impact/adhesion characteristic of the particles obtained through a Computational Fluid Dynamics (CFD) numerical simulation and the real size distribution of the contaminants in the air swallowed by the compressor. The kinematic characteristics (velocity and angle) of the impact of micrometric and sub-micrometric particles with the blade surface of an axial transonic and subsonic rotor are shown. The blade zones affected by particle impact are extensively analyzed. This work has the goal of combining the kinematic characteristics of particle impact on the blade with fouling phenomenon through the use of a quantity called ‘sticking probability’ adopted from literature. The analysis shows that particular fluid-dynamic phenomena such as separation, shock waves and tip leakage vortex strongly influence pattern deposition. The combination of the smaller particles (0.15 ― 0.25) μm and the larger ones (1.00 ― 1.50) μm determines the highest amounts of deposits on the leading edge of the compressor airfoil. The blade zones affected by deposits are clearly reported by using easy-to-use contaminant maps realized on the blade surface in terms of contaminant mass per unit of time. From these analyses, some guidelines for proper installation and management of the power plant (in terms of filtration systems and washing strategies) can be drawn.

The new generation of automotive controllers requires a space-constrained and high-efficiency step-down architecture. Hence, recently a potential alternative for the conventional step-down topologies is highly demanded. The new architecture should meet the high power density, high efficiency, wide operating ranges, high EMI capabilities, and low-cost requirements. This thesis, developed at the University of Padova and sponsored by Infineon Technologies, aims at investigating potential candidate topologies for automotive step-down conversion capable of eliminating or offsetting some of the common shortcomings of conventional solutions currently in use. Many research effort is paid for the soft switching quasi-resonant topologies in order to miniaturize the passive components through the switching frequency increase. However, the variable switching frequency, increased components count, and narrow operating ranges prevent the wide adoption of the quasi-resonant topologies in the target application. The first objective of this project is to investigate the quasi-resonant buck converter topology in order to stand on the limitations and operating conditions boundaries of such topology. The digital efficiency optimization technique, which is developed in this work, extends the operating ranges in addition to reduce operating frequency variations. On the other hand, the multilevel hybrid topologies are potentially able to meet the aforementioned requirements. By multiplying ripple frequency and fractioning voltage across the switching node the multilevel topologies have the direct advantage of reduced passive components. Moreover, multilevel topologies have many other attractive features include reduced MOSFET voltage rating, fast transient response, a Buck-like wide range voltage conversion ratio, and improved efficiency. These features candidate the multilevel topologies, in particular, the three-level flying-capacitor converter, as an innovative alternative for the conventional topologies for the target application. Accordingly, the three-level flying-capacitor converter (3LFC) is investigated as a second objective for this project. Flying-capacitor (FC) voltage balancing in such topology is quite challenging. The 3LFC under valley current mode control shows an interesting performance, where the FC voltage is self-balanced. In this work, the stability of the converter under valley and peak current mode control is studied and a simplified stability criterion is proposed. The proposed criterion address both current loop static stability and FC voltage stability. The valley current mode modulator results to be inherently stable as soon as the current static instability is compensated with an external ramp. On contrary, the FC voltage in peak current mode control (P-CMC) will never be balanced unless the converter operated with relatively high static peak-to-peak inductor current ripple. Since P-CMC has an inherent over-current protection feature, P-CMC based architectures are widely used in the industrial applications. However, in practice the peak current controlled three-level converter is inherently unstable. Consequently, the instability of the P-CMC 3LFC is addressed. A sensorless stabilizing approach, with two implementation methodologies, is developed in this work. The proposed technique eliminates the instability associated with the FC voltage runaway, in addition to FC voltage self-balancing. Moreover, the proposed methodology offers reduced size, less complexity, and input voltage independent operation. Besides, the proposed approach can be extended to system with a higher number of voltage levels with minimal hardware complexity. The proposed techniques and methodologies in this work are validated using simulation models and experimentally. Finally, in the conclusions the results of the Ph.D. activity are summarized and recommendations for the further development are outlined.

This study is focused on the design, optimization and analysis of non plug-in parallel and complex vehicles and on the evaluation of their potential to reduce fuel consumption and NOx emissions, in comparison with a reference vehicle. The simulated vehicles are equipped with compression ignition engines; two different engines were considered for the layout optimization process, and the related data were provided by GMPT-E (General Motors PowerTrain-Europe). A tool has been developed and employed to identify the optimal layout of each vehicle on the basis of the minimization of the overall powertrain costs during the whole vehicle life. These costs include the initial investment due to the production of the components as well as the operating costs related to fuel consumption and to battery depletion. The control strategy has been defined as the algorithm that selects the transmission gear and that manages the power to be provided by the engine and the electric machines of the power-train. In this framework, the transmission gear and the power management are the two control variables. Identification of the optimal control strategy is necessary in order to fully exploit the potential of the hybrid architecture to reduce fuel consumption and pollutant emissions. It is therefore carried out by the so-called optimizer in terms of a specific objective function. This function aims at maximizing the fuel economy with some constraints to the pollutant emissions and to the battery energy and life consumption, according to the application. To this end, two global optimizers, one of a deterministic nature and another of a stochastic type, have been developed, applied and compared. These methods are fundamental for the definition of the vehicle optimal control strategy. They are indeed referred to as benchmark optimizers. A zero-dimensional kinematic model of the vehicle has been developed in the Matlab environment in order to evaluate the evolution of the system variables, as a function of the vehicle velocity and of the control variables. A new mathematical technique has been developed and applied to the vehicle simulation model in order to decrease the computational time of the optimizers. First, the vehicle model equations were written in order to allow a coarse time grid to be used, then, the control variables were discretized, and the values of the system variables were evaluated and stored in a matrix, for all the possible combinations of control variables and for each time node, before the optimization process. However, since the benchmark optimizers are not suitable for on-board applications, one static optimizer and two different rule-based optimizers, which are referred to as real-time optimizers, have been also developed, compared to the benchmark tools and implemented in the vehicle control unit, in order to perform an on-board optimization. Usually this kind of optimization is based on heuristic techniques that may lack of performance in a broad range of applications. In this thesis, machine-learning techniques have been introduced to train the real-time tools. The training procedure that is applied to the rule-based optimizers consists of two parts: the input variable clustering and the rule definition. The vehicle velocity and power, as well as the battery state of charge, have been selected as the input variables. A clustering algorithm has been coded to discretize the input domain of the rule itself into a mesh, i.e., each combination of input variables is associated to an unique cluster. The rule connects every cluster to one of the discrete values of each control variable. Two different approaches have been followed in this study to develop the rule-based optimizers. A clustering algorithm has been developed for the first tool to generate the mesh that is associated to the rule, while genetic algorithms are applied to generate the action to take for each cluster of the mesh itself. In fact, the tool is referred to as Cluster Extracted Rule Optimized (CERO). Genetic algorithms have been instead applied for the second tool to generate the optimal mesh that is associated to the rule, while the most frequent action, in the set of actions that have been suggested by the benchmark optimizer in a cluster of the mesh, is correlated to that cluster. The tool is referred to as Cluster Optimized Rule Extracted (CORE). The vehicle control unit is required to receive the data about the instantaneous vehicle velocity, power and battery state of charge during the trip. These data are processed to identify the cluster they belong to, which is used to index the rule to extract the discrete values of the control variables. The control unit is therefore able to actuate the power-train components to drive the vehicle. The performance of the hybrid vehicles has been evaluated over several driving missions for different oriented optimizations and a detailed energetic analysis has been carried out in order to clearly identify the key operating modes that contribute most to the fuel consumption and NOx mission savings of the different hybrid architectures.

Alcune aree definite dall'Unione Europea nel contesto delle smart cities and communities si fondono pienamente con i motori elettrici come, per esempio, l'efficienza energetica, le tecnologie a basse emissioni di carbonio e la mobilità. I motori elettrici sono utilizzati in molteplici applicazioni industriali e non, consumando tra il 43% e il 46% dell'energia elettrica prodotta su scala mondiale.Nonostante alcune applicazioni siano contraddistinte da dinamiche elevate, come manipolatori o macchine utensili, la maggior parte di esse sono caratterizzate da basse dinamiche in quanto facenti parte di processi industriali, per esempio pompe, compressori, ventilatori o nastri trasportatori. Si è stimato che il costo dell'intero ciclo di vita di un motore elettrico è ascrivibile per il 92% - 95% all'energia consumata, il che indurrebbe un tempo di ritorno dall'investimento per installazione di un azionamento elettrico minore di due anni. Nonostante il notevole risparmio economico e ambientale ottenibile, è piuttosto sorprendente apprendere che solo il 10% - 15% di tutti i motori industriali siano controllati da azionamenti elettrici. Per quanto riguarda le diverse tecnologie di motori elettrici, i motori sincroni a riluttanza stanno ricevendo una notevole attenzione sia da ricercatori industriali che accademici. Il crescente interesse è principalmente motivato dalle loro intrinseche caratteristiche quali l'alta efficienza, il basso costo e il basso impatto ambientale dovuto alla mancanza di magneti permanenti. Per di più, le loro caratteristiche soddisfano appieno i requisiti imposti dalle smart cities and communities e sono adatti per tutte le applicazione, caratterizzate da una bassa dinamica, viste sopra. Per questi motivi, questa tecnologia di motori può essere posta al centro dei processi di rinnovamento di quelle applicazioni. Vi è ampio consenso sul potenziale incremento delle vendite sia di azionamenti elettrici che di motori sincroni a riluttanza. I motori sincroni a riluttanza sono soggetti a una marcata saturazione magnetica, rendendo i classici modelli a parametri concentrati poco adatti. La prima parte di questa tesi riguarda lo sviluppo di un innovativo modello magnetico per motori anisotropi. Si basa su una rete neurale non tradizionale, chiamata Radial Basis Function. La sua proprietà locale rende questo tipo di rete neurale particolarmente adatta ad un addestramento durante il normale funzionamento del motore. Si propone una completa procedura di design e addestramento della stessa. In particolare vengono fatte alcune considerazione le quali permettono di definire a priori alcuni parametri della rete neurale rendendo il problema di addestramento lineare. Si descrivono due algoritmi di addestramento, il primo veloce ma computazionalmente dispendioso perciò adatto per un'implementazione offline mentre il secondo idoneo ad un addestramento online. Infine, per concludere l'identificazione parametrica del motore, si propone uno schema basato sull'iniezione di una corrente continua il quale permette di stimare la resistenza di statore indipendentemente da tutti gli altri parametri della macchina. L'indipendenza parametrica permette un notevolmente miglioramento nell'accuratezza di stima del modello magnetico ottenuto con la rete neurale. La seconda parte di questa tesi, invece, tratta il controllo del motore e come sia possibile migliorarne le performance utilizzando il modello identificato. Innanzitutto, per incrementarne l'efficienza si presenta un innovativo metodo per trovare la curva a massima coppia per corrente. La tecnica proposta lavora in stretta simbiosi con l'identificazione del modello magnetico in quanto è in grado di capire dove si trova la curva cercata rispetto all'attuale punto di lavoro sfruttando la stima locale dei flussi magnetici. Identificata la direzione di movimento, l'azionamento continuamente muove il punto di lavoro coerentemente. Infine, si propongono tre diversi controlli di corrente pensati per gestire un motore fortemente non lineare, tutti basati sul modello stimato. Il primo è un controllore proporzionale-integrale nel quale i parametri vengono modificati al variare del punto di lavoro con lo scopo di mantenere la dinamica della corrente di motore costante. Il secondo è anch'esso basato su un controllore proporzionale-integrale ma a guadagni costanti accoppiato ad un'azione di feed--forward la quale compensa tutte le non linearità presenti nella mappa magnetica. Infine, il terzo è un controllo predittivo il quale determina direttamente la posizione degli switch tali per cui la funzione di costo è minimizzata. All'interno del controllo, è inserito un vincolo sulla corrente massima e si utilizza un particolare algoritmo per ottenere un lungo orizzonte di predizione. Tutti i metodi presentati nella tesi sono stata verificati attraverso dettagliate simulazioni e prove sperimentali, eccezione fatta per il controllo predittivo il quale è stato testato attraverso simulazioni.<br>Smart cities and communities are conjugated by European Union in different areas, including energy efficiency, low carbon technologies and mobility which are deeply merged with electric motors. Electric machines are ubiquitous in industry for a wide range of applications, consuming between 43% and 46% of all electricity that is generated in the world. Although some machines are used for high-performance applications, such as robots and machine tools, the majority are used in industrial processes for pumps, compressors, fans, conveyors, and other slower-dynamic applications. It is estimated that 92% - 95% of the life cycle costs of electric motors are associated with the energy they consume, leading to typical payback periods of < 2 years for the installation of an adjustable-speed drive. It is rather surprising to learn that, despite overwhelming evidence of the attainable savings, only 10% - 15% of all industrial motors presently use electronic adjustable speed drives. On the motor side, Synchronous Reluctance (SynR) motors are gaining lots of attention from industrial researchers and academics, due to their inherent characteristics like the high efficiency, the low cost and the low environmental footprint. Their characteristics fully meet the requirements imposed by smart cities and communities and the aforementioned low-dynamics applications, so they could be the heart of the revamping of those plants. There is wide agreement that the potential for future growth in the sales of industrial drives and SynR motors is still very substantial. SynR motors are prone to magnetic saturation, making the classic model with lumped parameters unsuitable. The main part of this thesis concerns the development of a new magnetic model for anisotropic motors, especially for SynR motors. It is based on a special kind of neural network (NN), called Radial Bases Function (RBF) NN, which is particularly advisable for an online updating due to its local property. A complete training procedure is proposed in which some considerations are done to define several NN parameters and to convert the nonlinear training problem into a linear one. Two different training algorithms are presented, the former one is fast but computationally cumbersome then suitable for an offline training while the latter one is lighter then proper for an online training. In order to complete the online parameters identification, a scheme based on a DC current injection is developed to estimate the stator resistance. An exhaustive analysis is carried out to disclose that the proposed method is independent from other motor parameters which is a strength asset in a saturable motor. An accurate stator resistance value improves in turn of the magnetic model. The second part of this dissertation deals with how to exploit an accurate magnetic model to enhance the motor control. In order to improve the efficiency of the motor, exploiting the RBF NN model and the online training algorithm, the Maximum Torque per Ampere (MTPA) curve is found. Starting from a blank NN, it is continuously online trained and a proper algorithm understands where the MTPA curve is respect to the current working point. Afterwards, the drive moves itself towards the actual MTPA. Finally, three different current control schemes tailored for anisotropic motors are presented, all based on the available NN-based magnetic model. The first one is a gain-scheduling PI control where the control gains are accordingly tuned to the working point to keep constant the control bandwidth. The second one is based on a classical PI regulator with a FF action to compensate for all the nonlinearity of magnetic maps. The third one is a constrained direct Model Predictive Control (MPC) where a long prediction horizon is achieved. In order to accomplish a long prediction horizon, the Sphere Decoding Algorithm is properly modified to make it suitable for a nonlinear system. The whole thesis was fully validated through an intensive simulation and experimental stage, except the long--horizon MPC which was tested only by simulation.

The instantaneous flow-rate in high-pressure pipelines of fluid power systems can be predicted by means of refined numerical models, the performance of which should be validated extensively against experimental pressure transients. However, such an approach in complex hydraulic systems can require an advanced modelling of the hydraulic, mechanical and electronic components and can therefore be cumbersome and ineffective. Experimental analysis is valuable to support the fast and complete evaluation of integrated electronic-hydraulic power systems, i.e., reciprocating pumps equipped with sophisticated regulation devices, gasoline and diesel fuel injection apparatus, anti-lock braking systems and traction-control systems. However, the state of the art only allows the unsteady high-pressure liquid flows in these systems to be characterized in terms of the pressure time-history measured at fixed locations. The situation is particularly critical for volumetric pumps, since the main mission of these components is the high-pressure instantaneous delivered flow-rate and one main aspect concerning the final judgement of their performance is related to the flow-rate ripple, which can only be evaluated approximatel. The selection of the operating principle for the flow-rate measurement in high-pressure pipelines can be considered challenging because miniaturized devices, capable of operating at high-pressure levels and characterized by a superior dynamic performance, are required. Obstruction meters, which relate the fluid velocity to the measured pressure drop across a calibrated orifice, offer steady measurements and are therefore not suitable for transients. On the other hand, positive displacement, turbine, and Coriolis flowmeters cannot generally be used because of their relatively low dynamic response (the cut-off frequency can reach 1 kHz) and their excessive overall sizes. As far as magnetic induction based flowmeters is concerned, they are characterized by high dynamic performance, but these meters require fluids with electrical conductivity as low as 0.1 S/cm, and diesel oil and gasoline both have much lower conductivity than this threshold. Finally, laser Doppler velocimetry-based techniques, which have been applied to the analysis of fluid dynamic transients in gasoline injection systems ([12]), imply a high initial setup cost, and are only applicable for laminar flows. Furthermore, these measurements require a pipe section made of quartz glass and this technique cannot therefore be applied when the pressure is higher than 100 bar. Flow-rate estimations, based on instantaneous pressure measurements, seem to be the most attractive opportunity, due to the superior dynamic response and the miniaturized sizes of the pressure transducers. Having assessed that pressure wave propagation occurs along a single direction, a mathematical relation exists between the pressure and flow-rate time-histories at any pipe section. On the other hand, the flow rate time-distribution cannot be inferred from the pressure time-history, measured at a single location, when the pressure waves travel back and forth through the pipeline, as usually occurs in engineering systems. An innovative methodology has been developed to evaluate the unsteady flow-rate in high-pressure pipelines, on the basis of the signals from two piezoelectric pressure transducers. A first-order non-linear ordinary differential equation was derived from Euler’s momentum balance and mass conservation equations, and was numerically solved to compute the instantaneous mass flow-rate. The flowmeter working principle was validated successfully through a comparison with numerical flow-rate data, which were predicted by means of a reliable one-dimensional model of a CR fuel injection system, and satisfactory accuracy and repeatability of the measurements were proved. However, the flowmeter algorithm required knowledge of the initial datum on the flow-rate, which can be difficult to infer. Furthermore, a complex procedure was required to remove the disturbances of the pressure transducer zero-offset errors from the measured pressure gradient. In particular, an additional piezoresistive transducer was needed to identify the presence of any possible time drifts in the piezoelectric transducer responses and to reference them, thus increasing the production costs of the device. Finally, the numerical discretization of an ordinary differential equation was required to evaluate the instantaneous flow-rate and this does not represent a very robust and efficient solution for a measuring device. During this Ph.D. course, which has been mainly focused on the numerical-experimental analysis of hydraulic power system, an optimized algorithm has been developed to evaluate the flow-rate on the basis of two pressure measurement performed in a high-pressure pipeline, and a definitive design has been proposed for the flowmeter previously studied. The newly designed and validated measuring device has been installed on the delivery pipe of a reciprocating pump in order to investigate the instantaneous flow-rate ripple, to validate a numerical model of the considered pump and to analyse the effect of the pump-integrated flow regulator on its hydraulic performance. A second application that will be analyses in the following sections concerns the installation of the proposed flowmeter to the inlet port of a hydraulic servo-valve. The activity was aimed at validating a numerical model of the test bench used to analyse the hydraulic behaviour of this kind of valve according to the ISO 10770-1 directive. The model has been subsequently used to perform some considerations about the overall hydraulic system. The flowmeter outputs have been also used for the development of a predictive model of a complete Common Rail (CR) injection system which is able to correctly simulate the rail pressure control system and the injector performance in steady-state and transients conditions with a deep degree of detail.

The research presented in this thesis involves different aspects related to advanced control methodologies and self-commissioning identification algorithms in modern electrical drives. The theoretical study and the validation of the results obtained were performed in the three years of Ph.D. at the Electric Drives Laboratory in the Department of Management and Engineering of the University of Padova, (VI) Italy. The research topics were mainly three, all related to the implementation and development of advanced controls for electric drives, aimed at a more efficient use of the electric machines in the modern mechatronic applications. The demand of electric drives capable of guarantee high-performance and flexible enough to update in real time the parameters involved in the control algorithm are the motivation of the present research, as well as the meshing or replacement of standard or obsolete control techniques with modern ones, able to fully exploit the new hardware resources. In order to contextualizes and motivate the choice of the present research in the world scenario, a comprehensive bibliographic framework can be found in the introduction of each chapter of the thesis. The part one of the thesis presents two new control architectures for Permanent Magnet Synchronous Motors, that is a type of electric machine notoriously appreciated by both academia and industry for its flexibility of use and controllability. To this aim, in Chap.2 is proposed a non-linear control algorithm for the automatic search of the Maximum Torque Per Ampere (MTPA) operating condition for Permanent Magnet Synchronous Motors with anisotropic structure, to be integrated in a conventional Field Oriented Control scheme. The exhaustive convergence and stability analysis performed in order to derive a new and original tuning method of the controller (proven by numerous experimental evidences) is definitely one of the distinguishing features in this research topic. In parallel to the first topic, for the same type of motor has been investigated and developed (first analytically and then by simulation) a speed and current Direct Predictive Control with Hierarchical decisional structure. Unlike the traditional control techniques, the proposed Direct Predictive Control with modified hierarchical control structure has a faster dynamic and the capability to impose different operating conditions aimed at the energy efficiency optimisation. The on-line execution of the algorithm required for the experimental validation, has become possible thanks to the adoption of a control platform based on FPGA logic (Chap.3). In fact, the processing speed provided by these devices, released from the execution of sequential instructions (typical of the architecture of the microprocessors), ensures an execution time of the algorithm contained in a few us. The part two of the thesis (i. e. Chap.5) presents an innovative technique of parameter identification for induction motors, capable of estimating the parameters of the equivalent inverse-Gamma electric circuit completely at standstill. As known, the saturations in the parameters of the magnetic circuit of the induction motor and the relative nonlinearities, deteriorate the performance of the standard sensored or sensorless vectorial controls. The studied self-commissioning procedure addresses and solves many problems related to the estimate of the non-linearity of the parameters, and then it can be considered as an evolution of the classical identification techniques in the literature. The practical feasibility, doubly validated by numerous experimental tests and by many finite element simulations on three different induction motors, concludes the chapter and proves definitely the method.<br>La ricerca presentata in questa tesi coinvolge molteplici aspetti che si legano alle più recenti metodologie di controllo studiate per azionamenti elettrici di ultima generazione. Lo studio teorico e la validazione in ambito sperimentale sono il frutto del lavoro svolto nel triennio di dottorato presso il laboratorio di azionamenti elettrici del Dipartimento di Tecnica e Gestione dei Sistemi Industriali dell’Università degli Studi di Padova. I temi di ricerca trattati sono principalmente tre, tutti legati alla realizzazione e allo sviluppo di algoritmi di controllo innovativi, capaci di incrementare l’efficienza e le prestazioni delle macchine elettriche di ultima generazione per applicazioni meccatroniche. Azionamenti elettrici in grado di garantire elevate prestazioni ma sufficientemente flessibili da aggiornare in tempo reale i diversi parametri coinvolti nel algoritmo di controllo sono il filo conduttore e la motivazione della presente ricerca, così come la sostituzione di logiche di controllo standard o obsolete con nuove architetture di controllo capaci di sfruttare le più recenti innovazioni hardware. Al fine di contestualizzare e motivare la ricerca condotta nel panorama mondiale, nell’introduzione di ciascun capitolo è inserito un esaustivo inquadramento bibliograficoinerente inerente il problema affrontato. La prima parte della tesi presenta due nuove architetture di controllo per motori sincroni a magnete permanente, tipologia di macchina elettrica notoriamente apprezzata dal mondo accademico e industriale sia per la sua flessibilità d’uso che per la sua facile controllabilità. In tal senso, nel Capitolo2 è descritto e formalizzato un controllo non lineare per motori sincroni a magnete permanente anisotropi, inseribile in schemi di controllo convenzionali ad orientamento di campo per ottenere la condizione di funzionamento a massima coppia su corrente (MTPA). L’esaustiva analisi di convergenza e stabilità condotta al fine di ottenere un nuovo ed originale metodo per la sintonizzazione del regolatore (comprovato da numerose evidenze sperimentali) è sicuramente una delle caratteristiche distintive per questo ramo della ricerca. Per la stessa tipologia di motore è stato poi sviluppato un controllo predittivo a stati finiti con struttura decisionale gerarchica. A differenza delle tecniche di controllo tradizionali, la soluzione studiata garantisce una dinamica veloce e la possibilità di imporre condizioni operative diverse, volte all’ottimizzazione e all’incremento dell’efficienza energetica. L’esecuzione on-line di tale algoritmo per le verifiche sperimentali si è resa fattibile grazie all’adozione di una piattaforma di controllo basata su logica FPGA (Capitolo3), in quanto la velocità di calcolo offerta da tali dispositivi, svincolata dall’esecuzione sequenziale delle istruzioni tipica dei microprocessori, garantisce tempi di esecuzione dell’algoritmo contenuti a pochi us. Nella seconda parte della tesi (Capitolo5) è presentata un innovativa tecnica di identificazione parametrica per motori asincroni, capace di stimare i parametri del circuito equivalente a Gamma-inverso del motore asincrono, a rotore fermo. Come noto, le saturazioni del circuito magnetico della macchina e le non linearità ad esso associate deteriorano le performances nei normali controlli vettoriali sensored e soprattutto sensorless. Il metodo di identificazione parametrica studiato affronta e risolve molti problemi connessi alla stima delle non linearità dei parametri, configurandosi a tutti gli effetti come un evoluzione delle classiche tecniche di identificazione presenti in letteratura. La fattibilità pratica del metodo, validata con innumerevoli prove sperimentali e simulazioni agli elementi finiti su tre diversi motori ad induzione, conclude il capitolo e prova in modo definitivo la realizzabilità del metodo.

La presente tesi riguarda la modellazione di diverse fonti di accumulo di energia elettrica, in particolare batterie e supercondensatori (SC), e di nuove configurazioni di metodi di gestione di sistemi di accumulo di energia ibridi . Il crescente bisogno di domanda di energia e il desiderio di raggiungere uno sviluppo sostenibile, si riflettono nell'uso di Generatori Distribuiti (DG) basati sulle Fonti energetiche Rinnovabili (FER). L'uso di un controllo di supervisione intelligente e il raggruppamento locale della domanda e della generazione possono portare a notevoli miglioramenti nell'efficienza, affidabilità e resilienza del sistema elettrico. Il problema principale della DG basata sulle FER è la variazione naturale di alcune fonti rinnovabili, come il vento e il sole. Per ridurre l'impatto della generazione intermittente delle FER, la soluzione più efficace e pratica è l'impiego di sistemi di stoccaggio dell'energia.<br>The present dissertation concerns about the modeling of different electrical energy storage sources, in particular batteries and supercapacitors (SCs), and of novel configurations of Hybrid Energy Storage Management Systems (HESMS). The growing need for energy demand and the desire to achieve sustainable development, are reflected in the use of Renewable Energy Sources (RESs)-based Distributed Generators (DG). The use of smart supervisory control and local clustering of demand and generation can lead to marked improvements in the efficiency, reliability, and resilience of the electrical system. The main problem of RESs-based DG is the natural variation of some renewable sources, such as wind and solar. To reduce the impact of intermittent RES generation, the most effective and practical solution is the employment of Energy Storage Systems (ESSs).

Hybridization and electrification of mobile working machinery are becoming promising areas of research and development for the off-highway industry. In this context, numerical modeling plays a fundamental role in predicting the performance of the vehicle transmission system and in optimizing its operation. A good design of the mechanical and electrical components of a hybrid transmission can be achieved only through an integrated approach. Regarding the hybrid electric traction, by means of the Ph.D. with high level training apprenticeship contract, I proceeded to the identification and analysis of some schemes in order to develop innovative solutions for the off-highway industry. I dealt with innovative solutions focusing on the modeling of industrial hybrid electric transmissions and agricultural electric powersplit transmissions. I chose to use AMESim as 1D multi-domain dynamic simulation tool. The results showed that an industrial vehicle equipped with an electric-hydrodynamic hybrid transmission, demonstrates 8% lower fuel consumption than a conventional vehicle. A representative working cycle defined by the author on the basis of the company experience and the data collected in literature was proposed as basis for comparison. Within the agricultural transmissions the electric variator has proved to be more competitive even better than conventional hydrostatic variator for power-split applications. I went into detail about the design of electrical machines and their related power and control technologies adopted for off-highway hybrid transmission considering also their integration into the mechanical system. This activity, aimed at the design of an electric drive for an industrial application, has allowed me to develop a model of electric motor, taking into account iron and copper losses, to be integrated in the simulation model of the complete vehicle. In this way, the electromagnetic and thermal design aspects were examined, identifying the parameters of optimization and the trade-offs that play a role in the design of a permanent magnet synchronous electric machine and in the development of the control algorithms. Having identified and quantified the benefits of hybrid solutions compared to conventional designs, thanks to the skills that I have acquired during the training period inside the company, my research has focused on the development of a preliminary design for a hybrid transmission, addressing also constructive aspects: from mechanical design to manufacturing and assembly. This concept will be tested in the research and development department of the company upon completion of the detailed design.<br>L'elettrificazione e l'ibridizzazione delle macchine agricole e industriali sono e saranno negli anni a venire le principali aree di ricerca e sviluppo per il settore off-highway. In questo contesto la modellazione numerica gioca un ruolo fondamentale nel predire le prestazioni del sistema di trasmissione del veicolo ed ottimizzare il suo funzionamento. Una buona progettazione della componente meccanica ed elettrica di una trasmissione ibrida può essere raggiunta solo tramite un approccio sistemico. Attraverso il percorso di Apprendistato in Alta Formazione ho proceduto all'individuazione di alcuni architetture realizzabili nell'ambito della trazione ibrido elettrica, ed alla loro analisi finalizzata allo sviluppo di soluzioni innovative per il settore. Ho affrontato soluzioni all'avanguardia concentrandomi sulla modellazione di trasmissioni industriali ibride elettro-idrodinamiche e trasmissioni agricole a ripartizione di potenza elettrica. Ho scelto di utilizzare AMESim come strumento di simulazione dinamica 1D multidominio. I risultati hanno dimostrato come un veicolo industriale equipaggiato con una trasmissione ibrida elettro-idrodinamica dimostri consumi di carburante inferiori dell'8% rispetto al veicolo convenzionale in un ciclo rappresentativo di utilizzo definito dall'Autore in base all'esperienza aziendale e a dati reperiti in letteratura. Nell'ambito delle trasmissioni agricole la ripartizione di potenza elettrica si è dimostrata concorrenziale se non vantaggiosa rispetto all'odierna ripartizione di potenza idrostatica. Sulla base dei modelli sviluppati, ho approfondito gli aspetti di progettazione delle macchine elettriche e le relative tecnologie di alimentazione e di controllo, anche in relazione con il loro impiego nei sistemi ibridi di trasmissione per applicazioni nel settore off-highway e alla loro integrazione con le componenti meccaniche. Questa attività, finalizzata alla progettazione di un azionamento elettrico per una applicazione industriale, mi ha consentito di definire un modello di macchina elettrica, completo di perdite, da poter integrare nel modello di simulazione del veicolo. In questo percorso, gli aspetti di progettazione elettromagnetica e termica sono stati approfonditi, permettendo di identificare i parametri di ottimizzazione ed i trade-offs che giocano un ruolo primario nella progettazione di una macchina elettrica sincrona a magneti permanenti e nello sviluppo degli algoritmi di controllo. Dopo aver identificato e quantificato i vantaggi delle soluzioni ibride rispetto alle trasmissioni tradizionali, grazie alla competenze che ho acquisito nel percorso di alta formazione in azienda, la mia attività di ricerca si è concentrata sullo sviluppo di un design preliminare per una trasmissione ibrida industriale, affrontando gli aspetti costruttivi, dal dimensionamento meccanico alla produzione ed assemblaggio. Una volta completata la progettazione di dettaglio, questo concept, verrà testato nell'ambito della ricerca e sviluppo di nuovi prodotti dell'azienda.

The interest on rotating electrical machines adopting permanent magnets (PMs) has increased during the past few decades, representing now a fashionable design option in a number of fields as industrial processing, transportation, actuators, household appliances and power plants. The issues related to an increasing electrical energy demand and consumption, have generated a tendency to research electrical drives with high efficiency, pushing electrical machines technology to further improvements. The introduction of permanent magnets based on rare earth, experienced since the 1960's, gave a great input in the development of innovative machine topologies. On the other hand, the increase and the instability of rare earth PMs price, especially between 2010 and 2013, have directed the research of rare earth free alternatives, or machines using a smaller amount of PMs. Actually, the current trend in the industrial and academic research focused on developing high performance electric motors and generators, among different electrical machines, highlights the Synchronous Reluctance (SynRel) and the Permanent Magnet Synchronous Reluctance (PMASynRel) motors as best candidates to satisfy the future energy and efficiency requirements. This thesis is comprehensively dedicated to theoretical and experimental analysis and design of the Synchronous Reluctance (SynRel) and the Permanent Magnet Assisted Synchronous Reluctance (PMASynRel) machines. In particular, it will be focused on electrical machines which power ratings are ranging from fraction of Watts to some hundred kWatts, for vehicular traction and house-hold appliances. SynRel and PMASynRel motors exhibit many technical advantages, like simple and robust structure, high torque density, high efficiency, small space required for PMs, high degrees of freedom in the design, high operating speed range, high overload capability, low back EMF (null in case of SynRel motors), leading to a safe behavior in case of inverter failure. Furthermore, thanks to the appropriate vector control algorithm, the performance in terms of efficiency and torque become highly competitive. The subject matter covered in the thesis is organized into three Parts, each including a certain number of chapters. % At the beginning of each Part, a brief summary is proposed aiming to describe the main content of that Part, the goals and the anticipation of the main results. Part I includes seven chapters summarizing the research activities carried out during the Ph.D. period. The first six chapters are dedicated to electrical machines for vehicular traction, while chapter 7 investigate on motors for house-hold appliances. Chapter 1 is mainly introductory and meant to provide the basics information to understand which are the pros and cons and the features of the machines under study. Chapter 2 summarize the design criteria and the electrical requirements of ferrite PMASynRel machine for traction application. The electromechanical performance have been evaluated and compared, in terms of torque and power. A brief description of the electric supply system in order to accurately and efficiently manage the motor for achieving the requested performance is presented. Chapter 3 highlights the influence and benefits of using ferrite magnets on the machine performance, emphasizing the importance of a careful evaluation of the magnet volume in order to increase the performance while reducing the used quantity. Chapter 4 is devoted to the sensitivity analysis of the machine performance in terms of torque ripple with respect to the geometrical design. An optimization algorithm has been performed in order to investigate and determine a rotor geometry which maximize the torque and reduces the torque ripple. The impact of the geometrical parameters is taken into account and the sensitivity of the optimal solution to the geometry variation is pointed out. This chapter highlights the difficulty to get a robust geometry as far as the torque ripple reduction is concerned. Finally, a few experimental results on a Synchronous Reluctance motor prototype will be presented, compared with Finite Element Analysis simulations for validation. Chapter 5 deals with the design and optimization of a high speed PMASynRel motor considering the driving cycles of an electric vehicle. A procedure is employed to evaluate the most effective design area, which has to be considered for the global optimization. Both results and advantages of the adopted methodology are highlighted. Further analysis on traction machines are going to be presented in Chapter 6. A comparison between ferrite and sintered NdFeB PMASynRel, SynRel and a Surface mounted PM (SPM) machines performance is deeply investigated. Chapter 7, the last of this first part, will highlight the advantages in using SynRel and PMASynRel motors for house-hold appliances. The main purpose of this chapter is to discuss the features of these motors as a valid substitute to commercial motors actually used for washing machines application. Part II is dedicated to the analytical modeling of SynRel machines with the challenge of predicting accurately the air-gap field of the machine taking into account the effect of the rotor flux barriers. This Part is divided into two chapters. Chapter 8 explains the hypothesis on which the analytical model is based, the calculation of stator Magneto Motive Force through winding function and describes the reluctance network equivalent circuit for a SynRel motor with one and two flux barriers per pole. The computation of the parameters of the model, the air-gap flux density and finally some comparison with Finite Element Analysis are presented. In Chapter 9 SynRel motors with split-phase stator winding sets supplied by multiple inverters have been investigated as an increasingly attractive solution for fault-tolerant, rugged, magnet-free vehicle traction drives. As an extension to the previous chapter, an analytical procedure to model and simulate a SynRel motor, with a split-phase stator winding, through a magnetic equivalent circuit (MEC) technique, has been introduced. As an output, the air-gap flux density of the SynRel motor can be computed at any operating point. Part III, finally, presents some experimental measurements carried out for two prototypes of SynRel and PMASynRel machines, with the purpose of comparing the results achieved in the motor optimization presented in Chapter 7.<br>In questi ultimi anni l’interesse per le macchine elettriche rotanti facenti uso di magneti permanenti ha riscontrato uno sviluppo sempre pi `u crescente. Tali macchine rappresentano un mondo alternativo alle tradizionali macchine sincrone e ad induzione, e vengono considerate ad oggi soluzioni promettenti in svariati settori, come quello industriale, per il trasporto, come attuatori, elettro domestici e per l’impiego in impianti di potenza. I problemi legati all aumento della domanda di energia elettrica ed al suo consumo, hanno generato una tendenza alla ricerca di azionamenti ad alta efficienza, spingendo la tecnologia delle macchine elettriche classiche ad ulteriori miglioramenti. L’introduzione dei magneti permanenti che utilizzano terre rare, gia dagli anni 60, hanno incentivato e permesso lo sviluppo di diversi tipi di macchina innovativi. Tuttavia, l’aumento e l’instabilita del prezzo delle terre rare, tra il 2010 ed il 2013, ha diretto la ricerca verso soluzioni di macchine alternative senza magneti permanenti, o con una quantita ridotta di tali materiali, pur soddisfando le specifiche di progetto. Al momento, la ricerca industriale e quella accademica sono entrambe focalizzate allo sviluppo di motori e generatori elettrici con elevate prestazioni, tra i diversi tipi di macchine elettriche esistenti, i motori sincroni a riluttanza (SynRel) ed a riluttanza assistita da magneti permanenti (PMASynRel) risultano essere degli ottimi candidati per il soddisfacimento delle specifiche energetiche e di efficienza, sempre piu stringenti, che verranno richieste ai motori nel prossimo futuro. Questo lavoro di tesi e interamente dedicato all’analisi teorica e sperimentale ed alla progettazione di motori sincroni a riluttanza (SynRel) e motori sincroni a riluttanza assistita da magneti permanenti (PMASynRel). In particolare, l’attenzione sar`a p osta su macchine elettriche in un campo di potenza che varia dalle centinaia di Watt alle decinedi kiloWatt, principalmente per applicazioni come veicoli elettrici ed elettro domestici. Tali macchine presentano una serie di vantaggi tecnologici che le portano ad avere prestazioni, soprattutto nel campo degli azionamenti a velo cit`a variabile (VSD), competitive rispetto ad esempio alle macchine ad induzione tradizionali o quelle a magneti permanenti. La struttura semplice e robusta, l’utilizzo ridotto di magneti permanenti, i gradi di liberta nella progettazione combinate ad un’elevata densita di coppia, alta efficienza elevate caratteristiche di sovraccarico ed un ampio campo di velocita, sono tutte caratteristiche che hanno permesso di collo care le macchine SynRel e PMASynRel in una posizione di rilievo. Inoltre, grazie all’aumento dei convertitori moderni a frequenza variabile e sistemi di controllo digitale, le prestazioni di questo tip o di motori, in termini di coppia ed efficienza, sono diventate altamente competitive rispetto ai tradizionali azionamenti con motori ad induzione.

Permanent magnets play a key role as a component in a wide range of devices utilised by many industries; they are widely used in several electromechanical applications to convert energy, including actuators, motors and sensors, home appliances, office automation equipment, speakers, aerospace, wind generators and more. Traditionally the adopted PMs were obtained from Rare Earth components, such as NdFeB, with high magnetic performance, but expensive. The research of alternative permanent magnets, in many cases has brought to choose the ferrites, mainly due to their low cost, but sometimes with significant design modifications of the final circuit, and possible increment of the weight. Permanent magnets can roughly be divided into two categories: sintered (metallic) and bonded, these last representing a valid alternative to the first. Bonded magnets consist of two components: a hard magnetic powder and a non-magnetic binder; the powder may be hard ferrite, NdFeB, SmCo, and is mixed with binders for compression or injection moulding. The benefits lie in the adoption of polymeric binders to prepare the magnetic mixture: the resulting magnetic characteristic can be then “tuned” by adopting different percentages of the plastic binder. Moreover, the realisation process is simpler and cheaper than that of sintered materials, and no special protective treatment is needed. The majority of the magnetic circuits are made with soft magnetic materials. Commonly laminated steels are adopted but recently the use of Soft Magnetic Composite (SMC) materials has increased representing a new solution to design the electrical machines with respect to traditional electrical steels. SMC materials are realized with pure Iron grains coated and insulated by means of a layer that should be organic or inorganic. With respect to traditional laminated steel, these materials present different advantages: the capability to lead the magnetic flux in all directions, the volume reduction, the possibility to realize components with new complex shapes and geometries, and the reduction of iron losses, mainly the eddy currents, at medium and high frequency. On the other hand, the mechanical performances, in terms of strength, are in general weak. Furthermore, a new material typology is introduced: the Hybrid Magnetic Composites (HMC), which are obtained with a combination of soft and hard magnetic materials mixed with a binder. The basic idea is that such materials should reflect the performance of AlNiCo magnets, low coercivity and adequate remanence, typically used in sensors applications. Prototypes of traditional and unconventional rotating machines, such as assisted reluctance motors, brushless DC motors, axial flux machines and electromechanical frequency converters, have been studied in own laboratories and tested to evaluate the results coming from the adoption of the proposed materials in substitution of the commonly adopted (and expensive) Rare Earth sintered magnets. Different type of electrical machines can adopt innovative magnetic materials with the aim to improve their performance. Induction motors are very useful and robust machines; on the other hand, such type of machines does not have a high dynamic behaviour. The DC motors can be easily controlled, but the presence of the brushes causes limitations on the efficiency, thermal restrictions and reduced life. The axial flux motors (AFM) have high efficiencies but the construction of the machines is very complex. The synchronous reluctance machines (SRM) have a lower cost compared to brushless ones. In general, the reluctance electrical machines don’t use permanent magnets. In this way, they have a reduction in the costs and allow a high overload capability. On the other hand, the lower power factor and power density, compared to PM synchronous motor (PMSM), are the main disadvantages. The filling of flux barriers with the permanent magnets allows the overcoming of these drawbacks. However, the regular ferrite and NdFeB sintered magnets cannot fill the flux barriers with complex geometries. For this reason, the use of bonded magnets can be a solution for a better utilization and design of flux barriers. Therefore different prototypes have been prepared and analyzed in our laboratories using SMC materials. Several experiments have been performed using dedicated test benches, where magnetic, energetic and mechanical aspects have been considered. On the other hand, with regard to HMCs, various magnets have been made in our laboratories, and different properties have been investigated: the effect of Iron content in the material and, also the binder content effect has been analysed.

This text focuses on advanced torque control of permanent magnet synchronous motor drives. A novel modular structure is introduced to simplify the design and implementation of Model Predictive Control (MPC). The layout consists of the control and the control framework. The dynamic control is the novel virtual flux controller, which is used to reach desired reference values, and the state observer, which is used to reduce effects of non-modeled system properties. The control framework consists of static mappings to simplify the control problem. Besides the alpha-beta and d-q transformations, a reference generation procedure is used to generate state references based on optimality criteria. Also, the actuation scheme is part of the control framework and defines the available input set and the resulting control properties. The first method actuates directly switch states, i.e. voltage vectors, which yield an integer set named Finite Control Set (FCS). The other method actuates duty cycles via modulation, which yield the Convex Control Set (CCS). A stability analysis is carried out for both, CCS-MPC and FCS-MPC. MPC is called stable, if it is feasible and convergent, which can be ensured using the main MPC stability theorem. However, stringent computation requirements make it difficult to apply the theorem in practice. Thus, the Lyapunov based MPC approach is applied to the motor drive, which provides stability guarantees independent of the prediction horizon. A stability constraint based on control Lyapunov functions (CLF) ensures convergence to the origin and the resulting optimal control problem is shown to be feasible for all time. In other words, a control input can be found at each sampling instant, which satisfies all constraints and yields a stable closed-loop system. The properties of CCS-MPC are derived using a nonlinear controller and the constrained closed-loop system is shown to be stable in the sense of Lyapunov. The stability properties of FCS-MPC are more complex due to the integer input set. Using set-theoretical methods, it is shown that a sufficiently large control error can be steered towards the origin. In other words, the proposed FCS-MPC is shown to be set stable, i.e. the control error is guaranteed to converge to a well-defined neighborhood of the origin. MPC requires that a Constrained Finite Time Optimal Control (CFTOC) problem is solved at each sampling time. Small sampling periods and limited computation capabilities of embedded hardware require the CFTOC to be sufficiently simple, which is achieved using the virtual flux model in the static reference frame. The problem size is contained using a sufficiently small prediction horizon and efficient algorithms are necessary to provide a result within a sampling period. The CFTOC of the proposed CCS-MPC is a (convex) linear or quadratic programming problem, which can be solved using existing efficient algorithms. To provide a minimal approach, an efficient algorithm is introduced to solve the one-step-ahead prediction CFTOC analytically. FCS-MPC results in a mixed integer programming problem and is therefore more difficult to solve with standard numerical methods. In practice, the CFTOC is solved by enumeration, which is combined with branch-and-bound, i.e. branch-and-cut, techniques to improve the computational efficiency. The control algorithms have been developed on a Software-in-the-Loop (SiL) platform based on Matlab/Simulink and the code is implemented without modification on an experimental test-bench. The evaluation confirms the design and implementation of CCS-MPC and FCS-MPC and shows good results in dynamic and steady-state operation. The two MPC approaches have complimentary properties, which can be used to target different applications. CCS-MPC achieves a constant switching frequency and is a promising alternative to proportional-integral (PI) vector control. The concept can be combined with different modulation schemes, e.g. the Symmetric Space Vector Modulation (SSVM) and the Discontinuous Space Vector Modulation (DSVM) are used in this text. FCS-MPC takes the inverter switching into account and achieves an approximately constant switching ripple but a variable switching frequency. The concept is most profitably applied to systems where a high sampling frequency compared to the switching frequency is desired, e.g. high power or servo drives. Moreover, FCS-MPC lacks Pulse Width Modulation (PWM) harmonics in its current spectrum. Consequently, it is advantageous in terms of acoustic noise since emphasized tones are missing. However, the distinguished PWM harmonics of CCS-MPC are simpler to filter. In summary, it can be said that the work on advanced torque control of permanent magnet synchronous motor drives has produced an innovative strategy. The introduction of a new structure has significantly simplified the model predictive control problem, the concept of stability in particular. Moreover, this structure results in the implementation of simple algorithms, which can be computed efficiently.<br>Il soggetto affrontato dal presente lavoro sono i controlli avanzati di coppia per azionamenti con un motore sincrono a magneti permanenti. A questo scopo, è stata introdotta una struttura modulare che semplifica la progettazione e l’implementazione del controllo predittivo basato su un modello (model predictive control, MPC): lo schema è costituito dal controllo dinamico e dal quadro di controllo. Il controllo dinamico è un regolatore di flusso virtuale, utilizzato per raggiungere un valore di riferimento voluto e un osservatore di stato che serve a ridurre gli effetti delle proprietà non modellizzate del sistema. Il problema del controllo è stato semplificato tramite l’utilizzo di trasformate statiche chiamate quadro di controllo. Accanto alle trasformate alpha-beta e d-q viene usata una procedura per la generazione di riferimenti di stato, basati su un criterio ottimale. Il quadro di controllo contiene anche lo schema di attuazione, che serve per definire l’insieme di ingressi disponibili. Da un lato, il controllore comanda in modo diretto l’accensione e lo spegnimento dei semiconduttori, ovvero i vettori di tensione, ottenendo un insieme finito d’ingressi (Finite Control Set, FCS). Dall’altro lato vengono attuati cicli di accensione (duty-cycles) attraverso una modulazione (pulse width modulation, PWM): ciò risulta in un insieme convesso d’ingressi (convex control set, CCS). È stata eseguita un’analisi di stabilità sia per CCS-MPC sia per FCS-MPC. MPC è stabile, se il problema di controllo ottimale ad esso associato è risolvibile e l’errore di stato converge all’origine. Tale stabilità può essere garantita attraverso il principale teorema di stabilità di MPC. Tuttavia, i requisiti di calcolo restrittivi rendono il teorema difficilmente applicabile nella pratica. Di conseguenza, viene introdotto l’approccio MPC basato su Lyapunov (Lyapunov-based MPC) per gli azionamenti, il quale fornisce garanzie sulla stabilità indipendentemente dall’orizzonte di predizione. Un vincolo di stabilità basato sulle funzioni di controllo di Lyapunov (control Lyapunov function, CLF) assicura la convergenza all’origine ed è stato provato che il problema ottimale di controllo risultante è sempre risolvibile. In altre parole, ad ogni istante di campionamento si può trovare un ingresso che soddisfi tutti i vincoli del sistema e renda stabile il sistema a circuito chiuso. Le proprietà di CCS-MPC vengono ottenute utilizzando un controllo non lineare ed è dimostrato che il sistema vincolato ad anello chiuso è stabile secondo Lyapunov. Le proprietà di stabilità di FCS-MPC sono più complesse a causa dell’insieme non continuo d’ingressi. Utilizzando metodi della teoria degli insiemi si dimostra che un errore di controllo sufficientemente ampio può essere diretto verso l’origine e tenuto in un dintorno dell’origine ben definito. MPC richiede che in ogni istante di campionamento si risolva un problema di ottimizzazione (constrained finite time optimal control, CFTOC). La limitata potenza di calcolo dei microcontrollori e la brevità dei periodi di campionamento richiedono un CFTOC relativamente semplice, che si può ottenere utilizzando un modello di flusso virtuale nel sistema statico di riferimento. Scegliendo piccoli orizzonti di predizione si limita la dimensione del CFTOC, la cui risoluzione necessità di algoritmi efficienti, che permettano di ottenere un risultato all’interno di un periodo di campionamento. Il CFTOC di CCS-MPC è un programma (convesso) lineare o quadratico (linear program, lp; quadratic program, qp) che può essere risolto tramite algoritmi efficienti e noti. Al fine di elaborare una strategia di tipo minimalista, viene introdotto un algoritmo efficiente che risolve analiticamente il problema con un orizzonte di predizione di un passo. Il CFTOC di FCS-MPC è un problema di programmazione lineare o quadratico a numeri misti interi (mixed-integer) ed è quindi più difficile da risolvere con metodi numerici standard. In pratica si calcolano tutte le soluzioni possibili, tra le quali viene scelta la soluzione ottimale. Per migliorare l’efficienza di calcolo si combina quest’approccio con tecniche branch-and-bound e branch-and-cut. Gli algoritmi di controllo sono stati sviluppati su una piattaforma software-in-the-loop (SiL) basata su Matlab/Simulink e il codice di programmazione è stato implementato su un banco di prova sperimentale, senza modifiche. La valutazione approva la progettazione e la realizzazione di CCS-MPC e FCS-MPC e indica buoni risultati sia nell’operazione dinamica che in quella stazionaria. I due approcci MPC hanno proprietà diverse che risultano vantaggiose per applicazioni differenti. CCS-MPC ha una frequenza di commutazione costante ed è un’alternativa promettente al controllo vettoriale proporzionale-integrale (PI). Il concetto può essere combinato con diversi schemi di modulazione, nella fattispecie si usa la modulazione simmetrica di vettori spaziali (symmetric space vector modulation, SSVM) e la modulazione discontinua di vettori spaziali (discontinuous space vector modulation, DSVM). FCS-MPC tiene conto della commutazione dell’inverter e raggiunge all’incirca un ripple di commutazione costante, ma ottiene una frequenza di commutazione variabile. Il concetto è vantaggioso per sistemi dove è richiesta un frequenza di campionamento alta rispetto alla frequenza di commutazione, per esempio azionamenti ad alta potenza o servoazionamenti. Inoltre, lo spettro della corrente di FCS-MPC non contiene armoniche PWM e di conseguenza è vantaggioso in termini di rumore acustico, data la mancanza di toni distinti. Tuttavia, le armoniche PWM distinte di CCS-MPC sono più semplici da filtrare. Si può concludere affermando che lo studio del problema dei controlli avanzati di coppia per azionamenti con un motore sincrono a magneti permanenti, ha portato all’individuazione di una strategia innovativa. L’introduzione di una nuova struttura di controllo ha semplificato notevolmente il problema di controllo predittivo, con particolare attenzione al concetto di stabilità. Inoltre, le implementazioni di tale struttura si sono rivelate particolarmente efficaci su piano computazionale.

L’oggetto di studio della presente tesi è una macchina utensile ad altra produttività con tavola rotante (transfer) che presenta numerosi elementi di innovazione rispetto a versioni precedenti. In particolare è stata ottimizzata la scelta dei materiali che compongono i vari elementi della struttura, sono stati ripensati gli impianti di servizio e, infine, è stato reso possibile l’impiego di tecnologie di lavorazione che permettono una notevole riduzione del consumo elettrico. Il transfer è costituito da una stazione di carico/scarico e da numerose stazioni di lavoro equipaggiate con moduli a tre assi che permettono di eseguire le diverse operazioni da realizzare sul componente in lavorazione. Le unità a tre assi vengono impiegate per movimentare gli elettromandrini che mettendo in rotazione gli utensili permettono l’esecuzione delle diverse lavorazioni. L’attività svolta è stata suddivisa in diverse fasi: nella prima è stata realizzata un’analisi funzionale che ha permesso di valutare (i) la rigidezza dell’unità a tre assi che equipaggia ogni stazione di lavoro e (ii) l’errore di posizionamento indotto dal riscaldamento delle viti di manovra che permettono la movimentazione dei tre assi della macchina. Nella seconda fase sono state valutate le potenzialità della tecnologia Minimum Quantity Lubrication (MQL) come alternativa ecologica ed economica alla tradizionale tecnica di lubrorefrigerazione con emulsione. La tecnica MQL consiste nel nebulizzare nella zona di taglio un aerosol composto da aria e olio. In particolare è stato calibrato il sistema di generazione dell’aerosol stesso ed è stata indagata l’influenza dei diversi parametri di taglio sulla qualità della lavorazione. Infine è stata effettuata un’analisi economica che ha permesso di valutare il vantaggio economico in termini di potenza installata e consumo di energia elettrica del transfer in relazione ad una macchina utensile di pari taglia che presenta le soluzioni costruttive standard per questa tipologia di dispositivo.

L’odierno mercato concorrenziale ha portato le aziende a rinnovare il sistema produttivo, spostandosi da un approccio innovativo convergente, in cui le imprese erano le uniche detentrici del controllo dell’intero processo, fin dalla generazione di nuove idee e proposte di innovazione, ad un approccio aperto, denominato Open Innovation, che fa leva sul concetto di flusso libero e bidirezionale di idee e tecnologie tra l’azienda e l’ambiente esterno. È in questo contesto che è stata progettata in Carpigiani una piattaforma e-maintenance chiamata Teorema che, sfruttando un sistema di telemetria, consente di monitorare in tempo reale le macchine installate presso l’utente finale, acquisendo importanti informazioni sul reale utilizzo e sulle effettive funzionalità impiegate dal cliente. Grazie a tale gestione remota, allo stesso tempo è possibile garantire un’efficace operazione di diagnostica e prognostica atte a prevenire eventuali malfunzionamenti. Il presente elaborato fornisce un concreto metodo di utilizzo di tale piattaforma per il monitoraggio real time di macchine per gelato espresso, al fine di verificarne l’effettivo utilizzo da parte del cliente ed il corretto dimensionamento dell’impianto. Per mezzo della piattaforma Teorema è stato inoltre possibile eseguire un’indagine comparativa sui consumi energetici misurati in macchina, testando l’efficienza di funzionamento. Infine è stata eseguita un’analisi FMEA degli allarmi rilevati sul parco di macchine analizzate, per valutare l’affidabilità della macchina e dei suoi componenti.

The present work deals with environmental sustainability and specific engineering solutions able to cope with such a global issue. Attention is focused on renewable energy and innovative fuels as effective strategies in contributing valuable techniques in order to face the need of mitigating environmental problems concerning climate change and global warming. The research study is targeted on optimized design and management of fluid machinery, and extensively on optimized energy conversion systems, conceptualized in accordance with current standards and regulations, governing the reference sector. The analysis investigates small energy supply from renewables (wind power) and innovative marine propulsion (alternative fuels and unconventional propulsion systems). Regulations and technical design are constantly focused for the study. The work proposes case solutions for energy design and management actions dealing with the theme of environmental sustainability: engineering analyses (design, technical-economical evaluation, performance results) for hybrid wind powered plants empowering SWRO (Sea Water Reverse Osmosis) desalination processes; engineering analyses (design, technical evaluation, performance results) for wind turbine rotors operating in sites characterized by a small wind resource; engineering analyses (design, technical evaluation, performance results) for marine ship propulsion empowered by LNG as an alternative sustainable fuel and by gas turbines as prime movers coupled to combined cycles as an innovative propulsion system (COGES configuration).

In questo elaborato viene analizzato il tema del design industriale applicato al mondo delle macchine per il confezionamento automatico, grazie al tirocinio per tesi svolto all'interno dell'azienda TMC - IMA. Il ruolo della progettazione, che interesserà tutto l'involucro di un innovativo macchinario dell'azienda, dovrà comunicare il grande valore del contenuto interno. Attraverso le successive fasi di sviluppo prodotto verranno indagati e sviluppati concetti chiave del design tra cui il rapporto forma-funzione, l'ergonomia, la facilità d'uso, la scelta dei materiali, le lavorazioni industriali, ma anche i dettagli tecnici e la riconoscibilità sul mercato. Gli strumenti di ricerca e quelli digitali serviranno come supporto e verifica delle scelte progettuali di cui questo testo vuole essere il racconto. L'obiettivo finale di questa tesi è dunque quello di sviluppare un prodotto che sia la sintesi coerente di tutti gli elementi fondamentali sopra citati.

Il mercato energetico negli ultimi anni è stato caratterizzato dallo sviluppo di diverse tecnologie definite “rinnovabili” che permettono di ottenere energia in modo pulito e inesauribile sfruttando le diverse risorse presenti sulla terra: eolica, solare, idroelettrica e geotermica. Parallelamente allo sviluppo di grandi centrali si sono sviluppate tecnologie per la realizzazione di piccoli impianti domestici in grado di rendere energeticamente autonome le abitazioni; tra queste tecnologie quella sicuramente più diffusa sono i pannelli fotovoltaici grazie anche ai forti incentivi che questi hanno ricevuto negli ultimi anni. Tuttavia questa tecnologia non è la più efficiente se non c’è abbastanza insolazione come nel nord dell’Europa o se non c’è uno spazio sufficiente e ben orientato per istallarli. Se ci si trova in queste condizioni e, allo stesso tempo, la zona d’istallazione è abbastanza ventosa (vento medio pari almeno a 5 m/s) la soluzione migliore è istallare una mini turbina eolica. Le mini turbine eoliche presenti in commercio si dividono in turbine ad asse verticale e ad asse orizzontale; le prime si dividono poi in turbine a resistenza o Savonius e turbine a portanza o Darrieus. Le turbine ad asse orizzontale sebbene siano la tipologia più comprovata non lavorano bene in zone caratterizzate da elevata turbolenza e frequenti cambi di direzione come avviene di solito vicino alle case o comunque ad altezze dal suolo minori di 25 m. Le turbine di tipo Savonius sono indipendenti dalla direzione del vento, poco sensibili alle turbolenze e riescono a lavorare anche con basse velocità del vento ma sono poco efficienti per la produzione di energia elettrica. Anche turbine di tipo Darrieus sono indipendenti dalla direzione del vento e poco sensibili alle turbolenze ma anche se sono caratterizzate 6 da elevati rendimenti, non riescono ad avviarsi se la velocità del vento è bassa. Il lavoro svolto in questi anni e raccolto in questa tesi è stato volto quindi alla ricerca di soluzioni innovative che potessero superare le problematiche delle turbine sopradescritte col fine di creare una nuova macchina in grado di lavorare bene nelle condizioni tipiche delle zone urbane e suburbane così da diventare un’alternativa sempre più valida ai panelli fotovoltaici. La prima parte del lavoro è stata quella di generazione concettuale: in questa fase sono state sviluppate diverse configurazioni fino a quando non è stata sviluppata la turbina a geometria variabile con i flap di avviamento, ritenuta un'ottima soluzione al problema. Terminato lo sviluppo concettuale, si è passati all’ottimizzazione fluidodinamica attraverso analisi CFD 2D e 3D transienti che hanno permesso la scelta di un profilo più performante rispetto a quello usato in una turbina commerciale. A partire dai dati delle analisi CFD è stata fatta la verifica strutturale dei vari componenti attraverso simulazioni FEM verificate poi con calcoli strutturali classici. Infine si è realizzato il prototipo della turbina che è tuttora in fase di test presso una galleria del vento realizzata in partnership con un’azienda di Termini Imerese.

Studio di una macchina automatica per l'avvolgimento con film estensibile di pallet dedicati al trasporto. Sono stati analizzati la storia del pallet, il mercato delle macchine avvolgipallet e lo studio di un motoriduttore. Successivamente si sono progettati i caratteri salienti della macchina e si sono dimensionato due motoriduttori.

The wheel - rail contact analysis plays a fundamental role in the multibody modeling of railway vehicles. A good contact model must provide an accurate description of the global contact phenomena (contact forces and torques, number and position of the contact points) and of the local contact phenomena (position and shape of the contact patch, stresses and displacements). The model has also to assure high numerical efficiency (in order to be implemented directly online within multibody models) and a good compatibility with commercial multibody software (Simpack Rail, Adams Rail). The wheel - rail contact problem has been discussed by several authors and many models can be found in the literature. The contact models can be subdivided into two different categories: the global models and the local (or differential) models. Currently, as regards the global models, the main approaches to the problem are the so - called rigid contact formulation and the semi – elastic contact description. The rigid approach considers the wheel and the rail as rigid bodies. The contact is imposed by means of constraint equations and the contact points are detected during the dynamic simulation by solving the nonlinear algebraic differential equations associated to the constrained multibody system. Indentation between the bodies is not permitted and the normal contact forces are calculated through the Lagrange multipliers. Finally the Hertz’s and the Kalker’s theories allow to evaluate the shape of the contact patch and the tangential forces respectively. Also the semi - elastic approach considers the wheel and the rail as rigid bodies. However in this case no kinematic constraints are imposed and the indentation between the bodies is permitted. The contact points are detected by means of approximated procedures (based on look - up tables and simplifying hypotheses on the problem geometry). The normal contact forces are calculated as a function of the indentation while, as in the rigid approach, the Hertz’s and the Kalker’s theories allow to evaluate the shape of the contact patch and the tangential forces. Both the described multibody approaches are computationally very efficient but their generality and accuracy turn out to be often insufficient because the physical hypotheses behind these theories are too restrictive and, in many circumstances, unverified. In order to obtain a complete description of the contact phenomena, local (or differential) contact models are needed. In other words wheel and rail have to be considered elastic bodies governed by the Navier’s equations and the contact has to be described by suitable analytical contact conditions. The contact between elastic bodies has been widely studied in literature both in the general case and in the rolling case. Many procedures based on variational inequalities, FEM techniques and convex optimization have been developed. This kind of approach assures high generality and accuracy but still needs very large computational costs and memory consumption. Due to the high computational load and memory consumption, referring to the current state of the art, the integration between multibody and differential modeling is almost absent in literature especially in the railway field. However this integration is very important because only the differential modeling allows an accurate analysis of the contact problem (in terms of contact forces and torques, position and shape of the contact patch, stresses and displacements) while the multibody modeling is the standard in the study of the railway dynamics. In this thesis some innovative wheel – rail contact models developed during the Ph. D. activity will be described. Concerning the global models, two new models belonging to the semi – elastic approach will be presented; the models satisfy the following specifics: 1) the models have to be 3D and to consider all the six relative degrees of freedom between wheel and rail 2) the models have to consider generic railway tracks and generic wheel and rail profiles 3) the models have to assure a general and accurate handling of the multiple contact without simplifying hypotheses on the problem geometry; in particular the models have to evaluate the number and the position of the contact points and, for each point, the contact forces and torques 4) the models have to be implementable directly online within the multibody models without look - up tables 5) the models have to assure computation times comparable with those of commercial multibody software (Simpack Rail, Adams Rail) and compatible with RT and HIL applications 6) the models have to be compatible with commercial multibody software (Simpack Rail, Adams Rail). The most innovative aspect of the new global contact models regards the detection of the contact points. In particular both the models aim to reduce the algebraic problem dimension by means of suitable analytical techniques. This kind of reduction allows to obtain an high numerical efficiency that makes possible the online implementation of the new procedure and the achievement of performance comparable with those of commercial multibody software. At the same time the analytical approach assures high accuracy and generality. Concerning the local (or differential) contact models, one new model satisfying the following specifics will be presented: 1) the model has to be 3D and to consider all the six relative degrees of freedom between wheel and rail 2) the model has to consider generic railway tracks and generic wheel and rail profiles 3) the model has to assure a general and accurate handling of the multiple contact without simplifying hypotheses on the problem geometry; in particular the model has to able to calculate both the global contact variables (contact forces and torques) and the local contact variables (position and shape of the contact patch, stresses and displacements) 4) the model has to be implementable directly online within the multibody models 5) the model has to assure high numerical efficiency and a reduced memory consumption in order to achieve a good integration between multibody and differential modeling (the base for the local contact models) 6) the model has to be compatible with commercial multibody software (Simpack Rail, Adams Rail). In this case the most innovative aspects of the new local contact model regard the contact modeling (by means of suitable analytical conditions) and the implementation of the numerical algorithms needed to solve the discrete problem arising from the discretization of the original continuum problem. Moreover, during the development of the local model, the achievement of a good compromise between accuracy and efficiency turned out to be very important to obtain a good integration between multibody and differential modeling. At this point the contact models has been inserted within a 3D multibody model of a railway vehicle to obtain a complete model of the wagon. The railway vehicle chosen as benchmark is the Manchester Wagon the physical and geometrical characteristics of which are easily available in the literature. The model of the whole railway vehicle (multibody model and contact model) has been implemented in the Matlab/Simulink environment. The multibody model has been implemented in SimMechanics, a Matlab toolbox specifically designed for multibody dynamics, while, as regards the contact models, the CS – functions have been used; this particular Matlab architecture allows to efficiently connect the Matlab/Simulink and the C/C++ environment. The 3D multibody model of the same vehicle (this time equipped with a standard contact model based on the semi - elastic approach) has been then implemented also in Simpack Rail, a commercial multibody software for railway vehicles widely tested and validated. Finally numerical simulations of the vehicle dynamics have been carried out on many different railway tracks with the aim of evaluating the performances of the whole model. The comparison between the results obtained by the Matlab/ Simulink model and those obtained by the Simpack Rail model has allowed an accurate and reliable validation of the new contact models. In conclusion to this brief introduction to my Ph. D. thesis, we would like to thank Trenitalia and the Regione Toscana for the support provided during all the Ph. D. activity. Moreover we would also like to thank the INTEC GmbH, the society the develops the software Simpack Rail, with which we are currently working together to develop innovative toolboxes specifically designed for the wheel rail contact analysis.