Eddy current angular position sensor for automotive

Programa doutoral em Líderes para Indústrias TecnológicasOs sensores angulares usados em aplicações automóveis, requerem uma boa resolução, fiabilidade, baixa manutenção, baixo custo de produção e capacidade de trabalhar sob condições adversas. Devido a estes requisitos, os sensores mais utilizados são os magnéticos, indutivos e magneto-indutivos. Outro fator crítico é a dimensão do sensor, quanto mais reduzido e compacto, maior é o número de aplicações em que pode ser aplicado. No caso dos sensores magneto-indutivos e indutivos, uma forma de reduzir o seu tamanho é através do uso de a bobines planares impressas em placas de circuito impresso (PCB). Estas, para além de mais compactas, conseguem também reduzir os custos de produção, otimizar a repetibilidade e assemblagem, e permitir que o seu desenho seja facilmente adaptado às suas aplicações. No desenvolvimento de sensores indutivos, obter a indutância das bobinas, que funcionam como elemento transdutor, é essencial e desafiador no caso de bobinas planas. Atualmente, há duas abordagens no estado da arte: fórmulas de aproximação (para geometrias regulares), e simulações de modelos de elementos finitos (FEM). As simulações são demoradas e recorrem a ferramentas de software dispendiosas e que exigem muitos recursos computacionais. Esta tese tem como objetivo desenvolver uma ferramenta de cálculo analítico para obter a indutância de bobinas planas genéricas, reduzindo o tempo de desenvolvimento. A ferramenta possibilita ainda o cálculo da interferência que um alvo planar condutivo tem na indutância da bobine, tornando assim possível obter a resposta de um sensor indutivo baseado em eddy currents durante a sua fase de desenvolvimento. Esta tese, além de detalhar o desenvolvimento da ferramenta mencionada, também descreve todos os processos de validação implementados, através de simulações FEM e testes experimentais. A metodologia proposta foi aplicada com sucesso no desenvolvimento de um sensor de posição angular automotivo baseado em eddy currrents. Foi possível comprovar que a precisão da ferramenta desenvolvida está de acordo com as metodologias usualmente utilizadas, com a vantagem de ser mais rápida e económica.Angular sensors used in automotive applications require good precision, reliability, low maintenance, low production costs and the ability to work in harsh conditions. Due to these requirements, magnetic, inductive and magneto-inductive sensors are preferred and are used in current generations of automotive angular position sensors. The size of the sensors is another relevant factor in the development of new solutions. The smaller and more compact, the larger the number of applications in which they can be applied. In the case of magneto-inductive and inductive sensors, one way to reduce their size is to use planar coils printed on printed circuit boards (PCBs). These, in addition to occupy a smaller volume when compared to solenoids, also reduce production costs and optimize repeatability and simplify assembly. When developing inductive sensors, knowing the required inductance value of its coils is essential and this task can be challenging in the case of planar coils. Currently, two approaches are used to calculate the inductances of planar coils. When the coils have regular geometry approximation formulas are used, configuring some parameters. When they have irregular geometry or a more accurate result is desired, simulations using finite element methods (FEM) are chosen. These simulations have the disadvantage of being time-consuming, requiring expensive software applications and a huge computing resources. In view of the budget and the reduction of development time, this thesis provides an analytical calculation tool for the inductance of generic multi-layer planar coils. In this way, it is possible to develop dedicated applications in reduced time. The tool also allows to calculate the interference that a planar conductive target, of arbitrary geometry, can have on the coil inductance. Thus, it is possible to obtain the response of an inductive sensor based on eddy currents during its development phase. This thesis, in addition to detailing the development of the aforementioned tool, also describes all the validation processes implemented using FEM simulations and experimental tests. The proposed methodology was successfully applied in the development of an automotive angular position sensor based on eddy currents. It was possible to prove that the precision of the developed analytical tool is in concordance with the methodologies usually used, with the advantage of being faster and open source.Fundação para a Ciência e a Tecnologia (FCT) - bolsa de doutoramento PD/BD/128142/201

Solução para sensores de posição angular imunes a campos magnéticos externos

Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e ComputadoresCom o aumento da utilização automóvel e da preocupação do impacto ambiental que estes causam, surgiu a necessidade de criar veículos mais ecológicos, encontrando-se neste momento a produção de carros híbridos e elétricos em expansão. Durante o desenvolvimento de carros elétricos, novos problemas surgem, assim como a necessidade de os resolver. Devido ao aumento da quantidade de cabos elétricos neste tipo de automóveis, novos campos magnéticos são gerados, causando novas interferências nos SPA (Sensor Posição Angular) magnéticos. Esta dissertação tem como objetivo estudar e implementar uma solução para um sensor de posição angular magnético, que seja imune a campos magnéticos externos de 3.2mT. Atualmente, este tipo de sensores não pode ser aplicado diretamente em carros elétricos, devido às dimensões dos campos magnéticos gerados pelos diferentes cabos, que excedem a perturbação mínima suportada por estes. A resolução deste problema tem bastante importância para a indústria automóvel, não só para a aplicação direta destes sensores em carros elétricos, mas também pelo facto de serem magnéticos e de não apresentarem, por isso, desgastes como os mecânicos, sendo uma vantagem notória a sua aplicação em mais partes do veículo. Nesta dissertação, de forma a resolver este problema, simulam-se e verificam- se várias possíveis soluções, com o recurso a ferramentas como o ANSYS e o Rhinoceros. Foram considerados parâmetros como a permeabilidade magnética e novas arquiteturas, usando princípios diferenciais e campos magnéticos gerados por bobines de Helmholtz. De momento já existem duas implementações que tornam os SPA magnéticos imunes a campos magnéticos externos. Uma delas incide na blindagem da região de interesse com um material de maior permeabilidade, sendo este responsável por atenuar os campos parasitas; a outra tem como base o princípio diferencial, onde o próprio sensor magnético anula os campos magnéticos externos homogéneos. Ambas as soluções são estudadas, sendo a primeira testada ao nível da simulação magnética, de forma a verificar a viabilidade da aplicação no caso em estudo.Nowadays, the main focus on the population’s mind is the environment, and how reduce the impact on it. Because of this and the electronic evolution, the number of sales of electric vehicles is increasing daily. Every day new ideas arise and new problems need to be solved. One of the topics targeted on research is the angular position sensors, based on magnetic effects. These kind of sensors present advantages, being the more profitable, the non mechanical wear, result of non contact between sensor’s parts. This characteristic makes them favourites when compared with other types of sensors. They can be applied in different parts of the vehicles, like pedals, to measure the pressure angle, and steering wheels, to measure the direction angle. On fuel vehicles magnetic angular sensors work seamless, but on electric vehicles this doesn’t happen, because the number and amplitude of magnetic fields increase substantially, induced by the higher number of electric cables. The electromagnetic interference is, in this case, superior than these type of sensor can handle, so they can’t be applied directly, on electric cars. The resolution of this problem has a huge importance to the automotive industry, since it can increase the range of applications. This sensor would be able to be applied in a larger range of measures, so the costs of the production’s vehicle would decrease, because they would have just one sensor doing the job of many. This dissertation has as main goal the study and development of a solution to the problem described. In order to do that, several simulations must be performed and different possible solution checked, using tools like ANSYS and Rhinoceros, managing parameters like magnetic permeability and methods like Helmholtz coil and differential principle

A fast and precise tool for multi-layer planar coil self-inductance calculation

An open-source tool that allows for a fast and precise analytical calculation of multi-layer planar coils self-inductance, without any geometry limitation is proposed here. The process of designing and simulating planar coils to achieve reliable results is commonly limited on accuracy and or geometry, or are too time-consuming and expensive, thus a tool to speed up this design process is desired. The model is based on Grover equations, valid for any geometry. The validation of the tool was performed through the comparison with experimental measurements, Finite Element Model (FEM) simulations, and the main analytical methods usually used in literature, with errors registered to be below 2.5%, when compared to standard FEM simulations, and when compared to experimental measurements they are below 10% in the case of the 1-layer coils, and below 5% in the 2-layer coils (without taking into consideration the coil connectors). The proposed model offers a new approach to the calculation of the self-inductance of planar coils of several layers that combines precision, speed, independence of geometry, easy interaction, and no need for extra resources.This work is supported by: European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) [Project nº 037902; Funding Reference: POCI-01-0247-FEDER-037902]. The work of Andreia Faria was funded by FCT—Fundação para a Ciência e Tecnologia under Grant PD/BD/128142/2016. The work of Carlos Ferreira was supported by the Fundação para a Ciência e Tecnologia (FCT) under Grant PD/BDE/135102/2017

High precision, geometry independent analytical method for self-inductance calculation in planar coils

This paper presents a versatile tool for the self-inductance calculation of planar coils. Due to the growing interest in planar coils in the past few years, the possibility of using an analytical model as a valid alternative to FEM simulations, regarding versatility and result reliability, would be of great interest. The ideal scenario would be to combine speed, precision, easy interaction and understanding, while adding versatility in terms of geometry. To achieve that, a tool, based on Grover equations, that calculates the self-inductance of planar coils with a general geometry has been developed. The results achieved using this method, considering different coil geometries and dimensions, were compared with the main analytical methods that can be found in the literature, proving the reliability of the proposed method. This model has the novelty of not having any limitation on the coil geometry or dimension, which is not the case for the other existing methods.This work has been supported by FCT – Fundação para a Ciência e Tecnologia with in the R&D Units Project Scope: UIDB/00319/2020 and European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COM-PETE 2020) [Project nº 037902; Funding Reference: POCI-01-0247-FEDER-037902]

Direct antiviral therapy for treatment of hepatitis C: A real-world study from Brazil

Introduction and objectives: Direct antiviral agents (DAAs) including sofosbuvir (SOF), daclatasvir (DCV), simeprevir (SIM) and ombitasvir, paritaprevir and dasabuvir were introduced 2015 in Brazil for treatment of hepatitis C virus (HCV) infection. The aims of this study were to assess effectiveness and safety of HCV treatment with DAA in real-life world in a highly admixed population from Brazil. Materials and methods: All Brazilian reference centers for HCV treatment were invited to take part in a web-based registry, prospectively conducted by the Brazilian Society of Hepatology, to assess outcomes of HCV treatment in Brazil with DAAs. Data to be collected included demographics, disease severity and comorbidities, genotype (GT), viral load, DAA regimens, treatment side effects and sustained virological response (SVR). Results: 3939 patients (60% males, mean age 58 ± 10 years) throughout the country were evaluated. Most had advanced fibrosis or cirrhosis, GT1 and were treated with SOF/DCV or SOF/SIM. Overall SVR rates were higher than 95%. Subjects with decompensated cirrhosis, GT2 and GT3 have lower SVR rates of 85%, 90% and 91%, respectively. Cirrhosis and decompensated cirrhosis in GT1 and male sex and decompensated cirrhosis in GT3 were significantly associated with no SVR. Adverse events (AD) and serious AD occurred in 18% and 5% of those subjects, respectively, but less than 1% of patients required treatment discontinuation. Conclusion: SOF-based DAA regimens are effective and safe in the heterogeneous highly admixed Brazilian population and could remain an option for HCV treatment at least in low-income countries