On the Sizing of the DC-Link Capacitor to Increase the Power Transfer in a Series-Series Inductive Resonant Wireless Charging Station

Wireless inductive-coupled power transfer is a very appealing technique for the battery recharge of autonomous devices like surveillance drones. The charger design mainly focuses on lightness and fast-charging to improve the drone mission times and reduce the no-flight gaps. The charger secondary circuit mounted on the drone generally consists of a full-bridge rectifier and a second-order filter. The filter cut-off frequency is usually chosen to make the rectifier output voltage constant and so that the battery is charged with continuous quantities. Previous works showed that an increase in power transfer is achieved, if compared to the traditional case, when the second-order filter resonant frequency is close to the double of the wireless charger excitation and the filter works in resonance. This work demonstrates that the condition of resonance is necessary but not sufficient to achieve the power increment. The bridge rectifier diodes must work in discontinuous-mode to improve the power transfer. The paper also investigates the dependence of the power transfer increase on the wireless excitation frequency. It is found the minimum frequency value below which the power transfer gain is not possible. This frequency transition point is calculated, and it is shown that the gain in power transfer is obtained for any battery when its equivalent circuit parameters are known. LTSpice simulations demonstrate that the transferred power can be incremented of around 30%, if compared to the case in which the rectifier works in continuous mode. This achievement is obtained by following the design recommendations proposed at the end of the paper, which trade off the gain in power transfer and the amplitude of the oscillating components of the wireless charger output

Design of contactless capacitive power transfer systems for battery charging applications

The main aim of the thesis, is to develop a high power system for small and large air-gaps applications, concurrently possessing high efficiency. To tackle the problems stated, two modified converters where proposed. The first proposed topology could yield higher power transfer for small air-gap applications. The topology proposed exhibits better efficiency and has several advantages compared to the existing topologies for small air gap applications. The second topology is called the Dual LC topology, which reduces the voltage stress across the capacitive interface enabling the CPT system to be used for large air gap applications. The Dual LC topology showcases excellent efficiency for variation in air-gap and under misalignment conditions. In final section of this thesis, the CPT system is extended to charging an industrial electric vehicle (IEV). As the requirement of charging an IEV varies depending on its battery pack. The power flow and control for the CPT systems is implemented

Fourier Analysis and Optimization of Inductive Wireless Power Transfer for Electric Vehicle Charging

With the growth of electric vehicle (EV) popularity, different charging options to increase user convenience and reduce charging time such as high power wireless charging are increasingly being developed and researched. Inductive wireless power transfer (WPT) systems for EVs must meet specifications such as stray field, battery power and voltage operating range, efficiency, and ground clearance. The coil geometry and design have a large impact in meeting these constraints. Typical design approaches include iterative analysis of predetermined coil geometries to identify candidates that meet these constraints. This work instead directly generates WPT coil shapes and magnetic fields to meet specifications and constraints through the optimization of Fourier basis function coefficients and that can be used to predict system efficiency and performance. The proposed Fourier Analysis Method (FAM) applies to arbitrary planar coil geometries and does not rely on iterative finite-element analysis (FEA) simulations. This flexibility allows for rapid design evaluation across a larger range of coil geometries and specifications. The method is used to consider the trade-off of coil current and stray field for given power levels to illustrate the flexibility and generality of the method. A 6.6 kW proof-of-concept demonstrator WPT system is built from the optimization result to compare model efficiency, stray fields, and performance to experimental measurements. The methodology is then used in the optimization, design, analysis, and testing of two 120 kW demonstrators, including thermal modeling and integration

Power quality improvement utilizing photovoltaic generation connected to a weak grid

Microgrid research and development in the past decades have been one of the most popular topics. Similarly, the photovoltaic generation has been surging among renewable generation in the past few years, thanks to the availability, affordability, technology maturity of the PV panels and the PV inverter in the general market. Unfortunately, quite often, the PV installations are connected to weak grids and may have been considered as the culprit of poor power quality affecting other loads in particular sensitive loads connected to the same point of common coupling (PCC). This paper is intended to demystify the renewable generation, and turns the negative perception into positive revelation of the superiority of PV generation to the power quality improvement in a microgrid system. The main objective of this work is to develop a control method for the PV inverter so that the power quality at the PCC will be improved under various disturbances. The method is to control the reactive current based on utilizing the grid current to counteract the negative impact of the disturbances. The proposed control method is verified in PSIM platform. Promising results have been obtaine

Aerial Drone Control Networks

The goal of this project is to create an easy-to-expand Unmanned Aerial Vehicle (UAV) platform capable of conducting coordinated wide-area reconnaissance. Our system uses a combination of off-the-shelf components and open-source software to enable custom mission creation. Each drone packages and sends image, position, and orientation data over a WiFi connection to a centralized ground station computer for processing. Potential applications for this system range from search-and-rescue to surveying and inspection

Standardization Roadmap for Unmanned Aircraft Systems, Version 2.0

This Standardization Roadmap for Unmanned Aircraft Systems, Version 2.0 (“roadmap”) is an update to version 1.0 of this document published in December 2018. It identifies existing standards and standards in development, assesses gaps, and makes recommendations for priority areas where there is a perceived need for additional standardization and/or pre-standardization R&D. The roadmap has examined 78 issue areas, identified a total of 71 open gaps and corresponding recommendations across the topical areas of airworthiness; flight operations (both general concerns and application-specific ones including critical infrastructure inspections, commercial services, and public safety operations); and personnel training, qualifications, and certification. Of that total, 47 gaps/recommendations have been identified as high priority, 21 as medium priority, and 3 as low priority. A “gap” means no published standard or specification exists that covers the particular issue in question. In 53 cases, additional R&D is needed. As with the earlier version of this document, the hope is that the roadmap will be broadly adopted by the standards community and that it will facilitate a more coherent and coordinated approach to the future development of standards for UAS. To that end, it is envisioned that the roadmap will continue to be promoted in the coming year. It is also envisioned that a mechanism may be established to assess progress on its implementation

Sustainable Mobility and Transport

This Special Issue is dedicated to sustainable mobility and transport, with a special focus on technological advancements. Global transport systems are significant sources of air, land, and water emissions. A key motivator for this Special Issue was the diversity and complexity of mitigating transport emissions and industry adaptions towards increasingly stricter regulation. Originally, the Special Issue called for papers devoted to all forms of mobility and transports. The papers published in this Special Issue cover a wide range of topics, aiming to increase understanding of the impacts and effects of mobility and transport in working towards sustainability, where most studies place technological innovations at the heart of the matter. The goal of the Special Issue is to present research that focuses, on the one hand, on the challenges and obstacles on a system-level decision making of clean mobility, and on the other, on indirect effects caused by these changes

Challenges and New Trends in Power Electronic Devices Reliability

The rapid increase in new power electronic devices and converters for electric transportation and smart grid technologies requires a deepanalysis of their component performances, considering all of the different environmental scenarios, overload conditions, and high stressoperations. Therefore, evaluation of the reliability and availability of these devices becomes fundamental both from technical and economicalpoints of view. The rapid evolution of technologies and the high reliability level offered by these components have shown that estimating reliability through the traditional approaches is difficult, as historical failure data and/or past observed scenarios demonstrate. With the aim topropose new approaches for the evaluation of reliability, in this book, eleven innovative contributions are collected, all focusedon the reliability assessment of power electronic devices and related components

Standardization Roadmap for Unmanned Aircraft Systems, Version 1.0

This Standardization Roadmap for Unmanned Aircraft Systems, Version 1.0 (“roadmap”) represents the culmination of the UASSC’s work to identify existing standards and standards in development, assess gaps, and make recommendations for priority areas where there is a perceived need for additional standardization and/or pre-standardization R&D. The roadmap has examined 64 issue areas, identified a total of 60 gaps and corresponding recommendations across the topical areas of airworthiness; flight operations (both general concerns and application-specific ones including critical infrastructure inspections, commercial services, and public safety operations); and personnel training, qualifications, and certification. Of that total, 40 gaps/recommendations have been identified as high priority, 17 as medium priority, and 3 as low priority. A “gap” means no published standard or specification exists that covers the particular issue in question. In 36 cases, additional R&D is needed. The hope is that the roadmap will be broadly adopted by the standards community and that it will facilitate a more coherent and coordinated approach to the future development of standards for UAS. To that end, it is envisioned that the roadmap will be widely promoted and discussed over the course of the coming year, to assess progress on its implementation and to identify emerging issues that require further elaboration

Photovoltaic generation with energy storage integrated into the electric grid: modelling, simulation and experimentation

Esta tese apresenta o trabalho e resultados da investigação desenvolvida sobre conversão fotovoltaica com armazenamento de energia integrado em rede elétrica. Começa por apresentar a modelação, simulação e validação da conversão fotovoltaica e inversores com injeção para a rede. Descreve também seguidamente o processo de conceção, construção, comissionamento e desenvolvimento experimental das infraestruturas hoje existentes na Cátedra Energias Renováveis da Universidade de Évora, no que diz respeito às duas microgrids desenvolvidas no âmbito do projeto europeu PVCROPS. Estas microgrids são compostas, de forma geral, por um elemento de produção fotovoltaica, um elemento de armazenamento de energia, uma ligação à rede e um sistema de controlo e datalogging. Relativamente ao armazenamento de energia, esta tese aborda e caracteriza ainda as duas tecnologias instaladas: a bateria de iões de lítio e a bateria de fluxo redox de vanádio. Estas microgrids servem assim para implementação e validação de uma estratégia de gestão de energia tendo como objetivo a maximização do autoconsumo, cujos conteúdos são apresentados no capítulo 4. Depois das conclusões, no último capítulo, apontam-se ainda as linhas de investigação futuras de maior potencial, na sequência do trabalho desenvolvido e apresentado nesta tese; Photovoltaic generation with energy storage integrated into the electric grid: Modelling, simulation and experimentation Abstract: This thesis presents the work and results of the research developed on photovoltaic conversion with energy storage integrated into the electric grid. It begins by presenting the modeling, simulation and validation of the photovoltaic conversion and inverters with injection into the electric grid. It also describes the process of design, construction, commissioning and experimental development of the existing infrastructures in the Renewable Energies Chair of the University of Évora, with respect to the two microgrids developed under the European project PVCROPS. These microgrids are generally composed by a photovoltaic production element, an energy storage element, a grid connection and a control and datalogging system. Regarding energy storage, this thesis also discusses and characterizes the two installed technologies: the lithium-ion battery and the redox-flow vanadium battery. These microgrids thus serve to implement and validate an energy management strategy with the objective of maximizing self-consumption, the contents of which are presented in Chapter 4. Following the conclusions, in the last chapter are pointed the future research lines of greater potential, following the work developed and presented in this thesis