A data centre can consist of a large group of networked servers and associated power distribution, networking, and cooling equipment, all that application consumes enormous amounts of energy as a small city, which are driving to a significant increase in energy inefficiency problems in data centre, and high operational costs. Also the massive amounts of computation power contained in these systems results in many interesting distributed systems and resource management problems. In recent years, research and technologies in electrical engineering and computer science have made fast progress in various fields. One of the most important fields is the energy consumption in data centre. In recent years the energy consumption of electronic devices in data centre, as reported by. Choa, Limb and Kimb, nearly 30000000 kWh of power in a year, may consume by a large data centre and cost its operator around £3,000,000 for electricity alone. Some of the UK sites consume more than this. In the UK data centre the total power required are amid 2-3TWh per year. Energy is the largest single component of operating costs for data centres, varying from 25-60%. Agreeing to many types of research, one of the largest losses and causes of data centre energy inefficiency power distribution is from the uninterruptible power supply (UPS). So a detailed study characterized the efficiencies of various types of UPSs under a variety of operating conditions, proposed an efficiency label for UPSs, also investigate challenges related to data centre efficiency, and how all new technologies can be used to simplify deployment, improve resource efficiency, and saving cost. Data centre energy consumption is an important and increasing concern for data centre managers and operators. Inefficient UPS systems can contribute to this concern with 15 percent or more of utility input going to electrical waste within the UPS itself. For that reason, maximizing energy efficiencies, and reduce the power consumption in a data centre has become an important issue in saving costs and reducing carbon footprint, and it is necessary to reduce the operational costs. This study attempts to answer the question of how can future UPS topology and technology improve the efficiency and reduce the cost of data centre. In order to study the impact of different UPS technologies and their operating efficiencies. A model for a medium size data centre is developed, and load schedules and worked diagrams were created to examine in detail and test the components of each of the UPS system topologies. The electrical infrastructure topology to be adopted is configured to ‘2N’ and ‘N+1’ redundancy configuration for each UPS systems technologies, where ‘N’ stands for the number of UPS modules that are required to supply power to data centre. This work done at RED engineering designs company. They are professionals for designing and construction of a new Tier III and Tier IV data centres. The aim of this work is to provide data centre managers with a clearer understanding of key factors and considerations involved in selecting the right UPS to meet present and future requirements.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This master s thesis proposes a three-phase transformerless double-conversion UPS with digital control system and reduced overall cost. The topology is composed of an input stage, a battery bank, an inverter, an auxiliary circuit and transfer switches. The input stage assumes the three-phase rectifier function with LCL filter in normal operation mode and is responsible for discharge the battery bank in backup mode. This configuration reduces the system cost since an available circuit is used to discharge the battery bank. In conventional double-conversion UPS topologies the input stage remains inactive during the backup mode and an additional circuit is employed for this purpose. The auxiliary circuit is formed by an inductor and a switching leg and is used as a battery charger during normal operation mode and is additionally used to balance the bus capacitors voltages in backup mode. In this configuration, the auxiliary circuit can be designed for only a fraction of the UPS rated power, also providing lower total system cost. Transfer switches change the configuration of the input stage and the auxiliary circuit according to the UPS operating mode. The detailed operation of the topology, modelling, digital control structure, and the results obtained by simulation are showed. Finally a 20 kVA prototype is implemented and experimental results are acquired for the validation of the employed design methodology as well as the proposed circuit functionality. / Esta dissertação de mestrado propõem uma topologia de fonte ininterrupta de energia (UPS - Uninterruptible Power Supplies) trifásica de dupla conversão sem transformador com custo reduzido e sistema de controle digital. A UPS proposta é composta por um estágio de entrada, um banco de baterias, um inversor, um circuito auxiliar e chaves de transferência. O estágio de entrada assume a função de retificador trifásico com filtro LCL em modo normal de operação da UPS e é responsável pela descarga do banco de baterias em modo bateria de operação. Esta configuração reduz o custo do sistema, pois permite que seja aproveitado um circuito disponível e dimensionado para a potência nominal da UPS para a descarga do banco de baterias. Em topologias convencionais de UPSs de dupla conversão o estágio de entrada permanece ocioso durante este modo de operação e um circuito adicional é empregado para este fim. O circuito auxiliar é formado por um indutor e um braço de interruptores e é utilizado como carregador de baterias em modo normal de operação e adicionalmente é utilizado para realizar o equilíbrio das tensões dos capacitores de barramento em modo bateria. Com esta configuração, o circuito auxiliar pode ser dimensionado para apenas uma fração da potência nominal da UPS, propiciando também a redução do custo total do sistema. As chaves de transferência alteram as configurações do estágio de entrada e do circuito auxiliar de acordo com o modo de operação da UPS. É apresentada a operação detalhada da topologia, a modelagem, a estrutura de controle digital utilizada e os resultados obtidos via simulação. Por fim, um protótipo de 20 kVA é implementado e resultados experimentais são adquiridos para a validação da metodologia de projeto empregada bem como da funcionalidade do circuito proposto.

fator de potÃncia e recurso para operar com dois valores de tensÃo de entrada. O mesmo à aplicÃvel a sistemas ininterruptos de energia do tipo dupla conversÃo ou on-line com caracterÃsticas de tensÃo de entrada bivolt (110 Vca e 220 Vca) e desta maneira à descartada a utilizaÃÃo de um autotransformador com seletor de tensÃo. O conversor em estudo à composto por dois conversores CA-CC boost clÃssicos, em que, para uma tensÃo de entrada de 110 Vca as entradas sÃo conectadas em paralelo e para uma tensÃo de entrada de 220 Vca as entradas sÃo conectadas em sÃrie. A ideia à fazer com que se tenha uma divisÃo equilibrada na entrada de cada conversor quando a tensÃo da rede elÃtrica for 220 Vca. Assim cada conversor boost clÃssico recebe metade da tensÃo total de alimentaÃÃo do conversor proposto. A estratÃgia de controle à baseada no controle por modo corrente mÃdia aplicada a ambos os conversores para proporcionar a correÃÃo do fator de potÃncia e a regulaÃÃo da tensÃo de saÃda. Para verificar o estudo teÃrico foi desenvolvido o projeto do circuito de potÃncia e controle validando atravÃs de resultados de simulaÃÃo e experimentais para um protÃtipo de 2,4 kW. Para a conexÃo paralelo e sÃrie das entradas, os resultados obtidos foram satisfatÃrios e o conversor operou adequadamente. / This work presents a study of a Double Boost AC-DC Converter with power factor correction and dual input voltage operation capability via a selector switch. Such converter can be applied to on-line uninterruptible power supplies with dual voltage input characteristics, this way avoiding the usage of a low frequency autotransformer. The studied structure is composed by two AC-DC classical boost converters, in which for input voltage of 110 Vac both its inputs are connected in parallel, and, for 220 Vac, they are connected in series. The control strategy is based in the average current mode control applied to both converters, in order to provide the power factor correction and output voltage regulation. Simulation and experimental results for 2.4 kW are presented, and so are validate the theoretical study and design. Connecting the inputs in parallel and series, the results were satisfactory and the converter operated properly.