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Advisor(s)
Abstract(s)
A emergĂȘncia das alteraçÔes climĂĄticas e subsequente preocupação com a redução das emissĂ”es de gases de efeito estufa, fez com que vĂĄrios setores de atividade tivessem de mudar o seu paradigma. Alguns desses setores, como o do transporte e da indĂșstria automĂłvel, tĂȘm investido progressivamente em soluçÔes de mobilidade elĂ©trica sustentĂĄvel como sĂŁo o caso dos veĂculos elĂ©tricos de zero emissĂ”es. Inequivocamente, as infraestruturas de carregamento tĂȘm uma importĂąncia elevada quer para agilizar esta mudança de paradigma, mas tambĂ©m para aumentar a disponibilidade de pontos de carregamento e aumentar o tempo de autonomia rodoviĂĄria. Para alĂ©m disto, as inovaçÔes das tecnologias de carregadores rĂĄpidos tendem a evoluir no sentido de que o tempo de carregamento seja cada vez mais semelhante ao tempo de abastecimento dos veĂculos de combustĂŁo interna. Como resposta a esta necessidade e considerando a relevĂąncia do tema, Ă© pretendido com esta dissertação realizar um modelo de simulação avançado de um conversor de potĂȘncia DC/DC de 100 kW. Para que tal seja possĂvel, Ă© necessĂĄrio primeiro estudar as infraestruturas de carregamento e analisar as soluçÔes de mercado existentes, de modo a propor uma solução cujas caracterĂsticas sejam atuais e preponderantes no mercado atual de carregadores DC. Com base nesta anĂĄlise, serĂŁo realizados os modelos elĂ©tricos e tĂ©rmicos do conversor, os sistemas de controlo inerentes, as metodologias para a seleção dos semicondutores de potĂȘncia e para a anĂĄlise e estimação de perdas, para que no fim seja possĂvel obter o nĂvel de eficiĂȘncia global do conversor para diferentes regimes de carga. Neste Ăąmbito foi constatado que as perdas de condução nos interruptores tĂȘm um peso significativo nas perdas totais, majoradas pela elevada magnitude da corrente modulada, contribuindo significativamente para a diminuição da eficiĂȘncia global. Para alĂ©m disso, no processo de descarga da bateria a eficiĂȘncia do conversor Ă© fortemente depreciada, motivada pela inversĂŁo do trĂąnsito de potĂȘncia e pela caracterĂstica assimĂ©trica das curvas caracterĂsticas dos semicondutores utilizados.
The emergence of climate change and subsequent concern with the reduction of greenhouse gases emissions caused many changes in the paradigm of several sectors of activity. Some of these sectors, such as transport and the automotive industry, have progressively invested in sustainable electric mobility solutions such as zero emission electric vehicles. Unequivocally, charging infrastructures are one of the points of interest, both to speed up this paradigm shift, but also to increase the availability of charging points and increase road autonomy. In addition, fast charger technologies advances in such a way to make the charging time closer to refuelling time of internal combustion vehicles. As a response to this need and considering the relevance of the subject, it is intended with this master thesis to realize an advanced simulation model of a 100 kW DC/DC power converter. To make this possible, firstly it is necessary to study the charging infrastructures and analyse the existing market solutions, in order to propose a solution whose characteristics are current and relevant in the current market of DC chargers. Based on this analysis, the electrical and thermal models of the converter, the inherent control systems, the methodologies carried out for the selection of power semiconductors and the analysis and estimation of losses will be carried out, so that in the end in order to determine the global efficiency for different load levels. In this context, the switches conduction losses have a major contribution in the total losses, increased due to magnitude of the modulated current, which has a significantly contribute to the decrease of overall efficiency. Furthermore, in the battery discharge process the efficiency of the converter is strongly depreciated by the inversion of power flow and by the asymmetric characteristic of semiconductorsâ characteristic curves.
The emergence of climate change and subsequent concern with the reduction of greenhouse gases emissions caused many changes in the paradigm of several sectors of activity. Some of these sectors, such as transport and the automotive industry, have progressively invested in sustainable electric mobility solutions such as zero emission electric vehicles. Unequivocally, charging infrastructures are one of the points of interest, both to speed up this paradigm shift, but also to increase the availability of charging points and increase road autonomy. In addition, fast charger technologies advances in such a way to make the charging time closer to refuelling time of internal combustion vehicles. As a response to this need and considering the relevance of the subject, it is intended with this master thesis to realize an advanced simulation model of a 100 kW DC/DC power converter. To make this possible, firstly it is necessary to study the charging infrastructures and analyse the existing market solutions, in order to propose a solution whose characteristics are current and relevant in the current market of DC chargers. Based on this analysis, the electrical and thermal models of the converter, the inherent control systems, the methodologies carried out for the selection of power semiconductors and the analysis and estimation of losses will be carried out, so that in the end in order to determine the global efficiency for different load levels. In this context, the switches conduction losses have a major contribution in the total losses, increased due to magnitude of the modulated current, which has a significantly contribute to the decrease of overall efficiency. Furthermore, in the battery discharge process the efficiency of the converter is strongly depreciated by the inversion of power flow and by the asymmetric characteristic of semiconductorsâ characteristic curves.
Description
Keywords
VEs Carregamento RĂĄpido Conversores de PotĂȘncia DC/DC Controlador PI Dual Active Bridge SiC MOSFET EV Fast Charging Power Converter PI Controller