Doctoral School

Reading date: 23/07/2024

• CAMPOS SALAZAR, JOSE MANUEL: Design and Analysis of Battery Chargers for Electric Vehicles Based on Multilevel Neutral-Point-Clamped Technology
  
  Author: CAMPOS SALAZAR, JOSE MANUEL
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRONIC ENGINEERING
  Department: Department of Electronic Engineering (EEL)
  Mode: Normal
  Deposit date: 30/05/2024
  Reading date: 23/07/2024
  Reading time: 11:00
  Reading place: ETSEIB: Defensa pública a la Sala de Presentacions 28.8-Avda. Diagonal, 647-Campus Sud, Barcelona
  Thesis director: BUSQUETS MONGE, SERGIO | FILBÀ MARTÍNEZ, ÀLBER
  Committee:
       PRESIDENT: TRILLA ROMERO, LLUÍS
       SECRETARI: BORDONAU FARRERONS, JOSE
       VOCAL: BARAIA-ETXABURU ZUBIAURRE, IGOR
  Thesis abstract: This thesis presents an exploration into the field of advanced battery charger design and control, addressing critical needs across a spectrum of modern applications. It first outlines the increasing importance of battery chargers in various domains, emphasizing the requirements of efficiency, adaptability, and reliability. A detailed review of existing technologies and control strategies underscores the urgent need for innovation in charger design.The focus of this research is the design and development of a battery charger topology. This topology is based on cascaded multilevel converters that provide bidirectional power flow and galvanic isolation. It addresses the charging requirements of multiple batteries connected in series and incorporates two distinct dc links. The charger develops from a three-level configuration to a four-level configuration, finally leading to a generalized n-level charger.Integral to this work is the formulation of comprehensive linear models, from state-space to s-domain representations, which highlight the charger's complex dynamics. This allows for an in-depth understanding of its operational behavior and control characteristics.The thesis also introduces a well-tuned control system that synchronizes the operation of the two multilevel converters. This ensures optimal operation of the charger. The ac-dc converter regulates the dc link voltage and grid power factor, while the dc-dc converter regulates the shared dc link voltage and battery bank charging currents. The user has the flexibility to determine which converter controls the dc-link voltage regulation.A key innovation is the independent charge control for each battery bank. This feature allows batteries to reach full charge independently, regardless of their initial state of charge or rated capacity. This improves overall efficiency and battery management.In addition, the thesis provides a practical and straightforward design methodology for compensators based on the charger's linear schemes. It employs uncompensated gain loops and uses Bode plots for effective tuning of compensator parameters.Finally, the thesis outlines future research directions. These include experimental validation, exploring vehicle-to-grid integration, exploring nonlinear control systems, assessing off-board charger viability, examining renewable energy integration, enhancing grid-supporting features, evaluating scalability and efficiency, and evaluating real-world applications. Together, these efforts promise to advance and optimize the proposed battery charger, placing it as a central element in the field of efficient and sustainable energy systems.
  

• GRATSEA, AIKATERINI: Introducing tools to quantify the performance of quantum computing algorithms and their applications.
  
  Author: GRATSEA, AIKATERINI
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN PHOTONICS
  Department: Institute of Photonic Sciences (ICFO)
  Mode: Normal
  Deposit date: 15/05/2024
  Reading date: 23/07/2024
  Reading time: 14:30
  Reading place: ICFO, Mediterranean Technology Park, Avinguda Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona
  Thesis director: LEWENSTEIN, MACIEJ | HÜMBELI, PATRICK
  Committee:
       PRESIDENT: TORRONTEGUI MUÑOZ, ERIK
       SECRETARI: ACÍN DAL MASCHIO, ANTONIO
       VOCAL: TOMZA, MICHAL
  Thesis abstract: In this thesis, I focused on introducing tools to quantify the performance of quantum computing algorithms and their applications. The main focus is on two of the most popular application areas of quantum computing, quantum machine learning and quantum chemistry. To this end, I analyze the properties of quantum machine learning models by following statistical method techniques, which can help us build our understanding of the capabilities of such quantum models. Moreover, I introduce the teacher-student scheme as a computational tool to benchmark the performance of different quantum models and their training capabilities. Until large-scale benchmarking is available, these tools can help us understand the potential of quantum machine learning and guide the research in the right direction. Next, in recent years substantial effort have been devoted to the development of quantum algorithms for quantum chemistry applications. I introduce tools to assess the utility of various combinations of quantum chemistry algorithms. I perform extensive numerical simulations on computationally affordable systems of intermediate size to explore how quantum methods can accelerate tasks of quantum chemistry. These works set a foundation from which to further explore the requirements to achieve quantum advantage in quantum chemistry. Finally, I discuss how research in quantum computing has tended to fall into one of two camps: near-term intermediate scale quantum (NISQ) and fault-tolerant quantum computing (FTQC). Through a quantum chemistry application, I explore how to use quantum computers in transition between these two eras, namely the early fault-tolerant quantum computing (EFTQC) regime.
  

• HÄGELE, SEBASTIAN: Compact Phase Imaging Platform and its Application to Material Science and Manufacturing
  
  Author: HÄGELE, SEBASTIAN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN PHOTONICS
  Department: Institute of Photonic Sciences (ICFO)
  Mode: Normal
  Deposit date: 20/06/2024
  Reading date: 23/07/2024
  Reading time: 14:30
  Reading place: ICFO, Mediterranean Technology Park, Avinguda Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona
  Thesis director: PRUNERI, VALERIO | TERBORG, ROLAND ALFONSO
  Committee:
       PRESIDENT: FELIX PEREIRA, SILVANIA
       SECRETARI: ARTIGAS GARCIA, DAVID
       VOCAL: VOGL, ULRICH
  Thesis abstract: As the world moves towards increasingly miniaturized and complex technologies and devices, the need for imaging and metrology tools for precise material characterization and fabrication process control is rising accordingly. For highly transparent and ultra-thin structures and samples (e.g., optical coatings, lithographic structures or biological cells), intensity-based imaging techniques fall short due to insufficient contrast, as well as failing to provide quantitative information.To overcome these limitations, the field of phase imaging, based on superposition and interference of light, has emerged. In order to create image contrast, phase imaging does not leverage changes in intensity, but rather, as the name implies, changes in the phase of the electro-magnetic wave. With a long-standing history, and Nobel prizes awarded in 1953 to Zernike’s “phase contrast microscope” and 1971 to Gabor’s holographic methods, the field has evolved to “quantitative phase imaging” (QPI), using sophisticated methods and setups to control and manipulate the state of light in order to recover the phase information quantitatively. Herein, the category of “common-path” techniques promises adaptable, compact, robust, and cost-efficient imaging devices, enabling use in industrial applications outside of a well-controlled lab environment.In this thesis, we will describe the development and technological innovations of a “common-path” phase imaging platform based on the “lateral-shearing interferometric microscopy” (LIM) technology. We will implement and adapt the platform to various optical setups, e.g., for large-area lens-free imaging and for high-resolution microscopic imaging. We will also demonstrate the performance and versatility of the platform by exploring a range of applications, with a focus given to material science and manufacturing. Specifically, we will perform volumetric imaging of the tiniest femtosecond laser-written refractive index (RI) changes inside glass. This is followed by the characterization of semi-transparent ultra-thin gold films using multispectral intensity and phase imaging, enabling us to determine the complex RIs of the films of varying thickness. Lastly, we will apply the platform to the imaging of curing grades and RI changes in photopolymers, such as those used in resin-based 3D printing. Further applications of the platform could include surface metrology, imaging of 2D materials, as well as quantitative phase imaging for bio- and cell-imaging applications, with the possibility of integrating the whole platform into a compact add-on which could be added to any commercial microscope. In summary, this thesis will make evident the significant potential of phase imaging in both research and industrial settings, enabled by the proposed compact phase imaging platform. The work builds the foundation for future innovations and developments with a potentially lasting impact on the photonics industry.
  

• IÑIGUEZ AMIGOT, JOSÉ IGNACIO: Estrategias de Control de Potencia en Inversores de Generación Distribuida ante un Fallo Desbalanceado de la Red Eléctrica
  
  Author: IÑIGUEZ AMIGOT, JOSÉ IGNACIO
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRONIC ENGINEERING
  Department: Department of Electronic Engineering (EEL)
  Mode: Normal
  Deposit date: 11/06/2024
  Reading date: 23/07/2024
  Reading time: 10:00
  Reading place: Defensa pública a l'Aula Màster, Escola Politècnica Superior d'Enginyeria de Vilanova i la Geltrú (EPSEVG)
  Thesis director: MIRET TOMAS, JAUME | CAMACHO SANTIAGO, ANTONIO
  Committee:
       PRESIDENT: GARCERÁ SANFELIU, GABRIEL
       SECRETARI: GARCIA DE VICUÑA MUÑOZ DE LA NAVA, JOSE LUIS
       VOCAL: FIGUERES AMORÓS, EMILIO
  Thesis abstract: This PhD thesis examines various reactive current injection techniques and strategies to address the challenges associated with power grid management during abnormal conditions. The aim is to offer new perspectives and practical solutions to improve the operation and reliability of the power system. To this end, three contributions are presented. The first contribution focuses on a new control approach for reactive current injection in distributed generation systems. The method proposes a method of independent reactive current injection for each phase, which optimises the system's ability to handle load imbalances and fault events. In addition, peak current control is incorporated to protect inverters, ensuring safe and efficient performance. The second contribution focuses on improving voltage support in isolated microgrids during short-circuit events. An innovative strategy is introduced that uses electric vehicles to provide voltage support by injecting active power, instead of conventional reactive injections. This approach not only improves system stability during disturbances, but also avoids unwanted overvoltages through coordinated control between distributed generators and electric vehicles. The third contribution proposes a control scheme for the remote elimination of voltage unbalance in grid-connected inverters. This approach uses the virtual grid concept to compensate negative sequence voltage at remote points of the power system. In addition, it integrates peak current control to protect inverters and ensure optimal performance with low control data traffic. To summarise, these contributions address various aspects of the operation and control of distributed generation systems and microgrids, including reactive current injection and voltage unbalance compensation. They provide innovative and efficient solutions to enhance grid stability and security.
  

• PAZMIÑO FLORES, YADIRA CARMEN: Evaluación de los usos de suelo y valor ecosistémico del páramo de la Subcuenca Chambo (Ecuador)
  
  Author: PAZMIÑO FLORES, YADIRA CARMEN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN SUSTAINABILITY
  Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
  Mode: Article-based thesis
  Deposit date: 17/04/2024
  Reading date: 23/07/2024
  Reading time: 11:00
  Reading place: ETSECCPB, Sala Conferències C2-212 (C/Jordi Girona 1-3, mòdul C2, Campus Nord, Barcelona).
  Thesis director: FELIPE BLANCH, JOSE JUAN DE | VALLBE MUMBRU, MARC
  Committee:
       PRESIDENT: AGUILERA BENAVENTE, FRANCISCO
       SECRETARI: ALCARAZ SENDRA, OLGA
       VOCAL: GUAITA PRADAS, INMACULADA
       VOCAL NO PRESENCIAL: HERNÁNDEZ CLEMENTE, ROCÍO
       VOCAL NO PRESENCIAL: GILABERT NAVARRO, M. DESAMPARADOS
  Thesis abstract: The scarcity of information that allows understanding the importance of natural resources from an economic approach is a limitation to establish parameters related to environmental investment in conservation plans. This research proposes a methodology that allows modeling the variability of páramo land uses and the Ecosystem Valuation (EV) of the Chambo-Ecuador sub-basin from a bioeconomic monitoring that links the economic rent of páramo land uses with remote sensing tools and geographic information systems. The main results of the methodology determined that temporal monitoring of land covers is essential to identify areas of greatest vulnerability to EV degradation. The thresholds, functions and interrelationships determined in the Cart Decision Tree (CDT), Multilayer Perception (MLP), Multivariate Adaptive Regression Splines (MARS) and Support Vector Machines (SVM) models for land cover recognition were efficient; the models performed 88%, 85%, 83% and 81% respectively. The hybridization of the models, Markov chains and cellular automata was appropriate for predicting future land cover changes in Andean areas in relation to their VE, the methods achieved acceptable accuracy for recognizing páramo land uses. The variables chosen for land cover classification were adequate to identify land cover particularities.The opportunity cost and benefit transfer methods proposed obtained a good performance in the evaluation of food production trajectories linked to environmental services (ES) of carbon supply and concentration associated with indirect and support ES, so it was determined that the information from the dynamics of environmental services is an important indicator to understand the real state of the resource and consequently allows understanding the necessary strategies to undertake sustainable actions for ecological management.The mapping generated allowed us to determine that the páramo decreased by 13% between 2000-2010 and 19% between 2010-2020. It was estimated that the loss of the ecosystem between 2000 and 2030 will increase to 28%. From the first year of the study to the last year considered in the work, the páramo will go from occupying 92% to 64% of the area studied. The changes in the EV reveal that the categories with anthropogenic activity analyzed maintain a constant growth that has a direct impact on the EV of the páramo. The most affected areas are those up to 3500 meters above sea level. The EV of the Chambo sub-basin from 2000 to 2020 will increase from 2.86×108 USD to 2.59×108 USD and it is estimated that by 2030 the EV will decrease to 2.48×108 USD, which leads us to recognize that, although the loss of the EV of the natural resource is not critical, its degradation is increasing.Through this methodology it will be possible to obtain, in a practical way, data on the conservation status of the resource over time, allowing to solve problems related to the scarcity of data and leading to the understanding of changes in the area from a socioecological approach, i.e., covering the environmental impacts of human activities on natural systems. The basis of the developed method allows replication of the methodology.The information generated by this study will be of vital importance to understand the causes of the changes in the Andean systems in monetary and environmental terms, which will allow the development of management plans and conservation policies aimed at protection and sustainable management from an economic approach.