This thesis deals with a new solution for medium voltage drives. Load Commutated Inverter (LCI) fed synchronous motor drive is a popular solution for high power drive applications. Though the induction machine is more rugged and cheaper compared to the synchronous machine, LCI fed induction motor drive solution is not available. The basic advantage of a synchronous machine over an induction machine is the fact that the synchronous machine can operate at leading power factor. Due to this property load commutation of SCR switches of the LCI is achievable for synchronous machine. On the contrary an induction machine always draws lagging power factor current; this makes it unsuitable as a drive motor for LCI technology. In this thesis a new LCI fed induction motor drive configuration is developed as an alternative for synchronous motor drives. A new variant of six phase induction motor is proposed in this context. The machine is named as Active Reactive Induction Machine (ARIM). The ARIM contains two sets of three-phase windings with isolated neutral. Both the windings have a common axis. One winding carries the active power and can be wound for higher voltage (say 11kV). The other winding supplies the total reactive power of the machine and can be wound for lower voltage (say 2.2 kV). The rotor is a standard squirrel cage. High power induction machines usually demand lesser magnitude of reactive power compared to the total power rating of the machine ( 20% ). Therefore excitation winding has a smaller fraction of the total machine rating compared to the power winding. A VSI with an LC filter supplies reactive power to the ARIM through the excitation winding and ensures leading power factor at the power winding. This is similar to the excitation control of the LCI fed synchronous machine. The direct VSI connection is possible due to the lower voltage rating for the excitation winding. In this way, the VSI voltage rating does not limit the highest motor voltage that can be handled. An LCI supplies the real power into the ARIM from the power winding. The LCI currents are quasi square wave in shape. Therefore they have rich low order harmonic content. They cause 6th and 12th harmonic torque pulsations in the machine. This is a problem for the LCI fed synchronous machine drive. In the proposed drive, the VSI can compensate these low frequency m.m.f. harmonics inside the machine air gap to remove torque pulsation and rotor harmonic losses. The advantage of the proposed topology is that no transformer is required to drive an 11kV machine. It is always desirable to feed sinusoidal voltage and current to both the power winding and the excitation winding. To address this problem, a second configuration is proposed. A low power three-level VSI is connected in shunt at the power winding with the proposed ARIM drive as discussed above. This VSI compensates the low frequency harmonic currents to achieve sinusoidal motor currents at the motor winding. This VSI acts as a shunt active filter and compensates for the lower order harmonics injected by the LCI. The proposed topologies have LC filters to maintain sinusoidal motor voltages and currents by absorbing the VSI switching frequency components. But the motor terminal voltage oscillates at system resonant frequency due to the presence of LC filters. These resonant components in the terminal voltages are required to be eliminated for smooth terminal voltages and safe load commutation of the thyristors. In this thesis a simple active damping method is proposed to mitigate these issues. The proposed topologies are experimentally verified with an ARIM with 415 V power winding and 220 V excitation winding. The control is carried out on a digital platform having a TMS 320LF 2407A DSP processor and an ALTERA CYCLONE FPGA processor. Results from the prototype experimental drive are presented to show the feasibility and performance of the proposed drive configurations.

Products, throughout their life cycle from production to waste management, create emissions of greenhouse gases (GHG). This leads to environmental impacts on the climate (Swedish Environmental Protection Agency, 2016). The consumed products from households are increasing (World Wildlife Fund, 2008) and so is the waste generated from them (Avfall Sverige, n.d.). A more sustainable development generating from circular economy should be focused on to increases the reuse of products and by so reduce the amount of waste generated (Göteborgs Stad, n.d.a.) This study have examined if the use of Free Shops can help the city of Gothenburg to reach higher up the waste management hierarchy towards reuse and prevention, and if carbon dioxide equivalents (CO2e) can be avoided by using Free Shops.    Two Free Shops with the purpose to increase reuse in Gothenburg have been studied and their effect on GHG emissions, presented as CO2e, have been analysed. A Life Cycle Inventory Study (LCI) has been conducted on all, but two, different materials entering the Free Shops for four weeks, including the production, waste management, transportation and storage. The result of the study shows that a mean of 10 ton CO2e per Free Shop per year can be avoided when reusing at a Free Shop instead of buying new products. This equals leaving a low energy lamp on for approximately 590 years (World Wildlife Fund, 2009) based on a low energy lamp using 0,007 kWh (Eon, 2007). To examine if the Free Shops can reduce the amount of waste disposed of by households in Gothenburg the material entering the Free Shops was weight and analysed to estimate how it corresponded to the amount of waste disposed of. The result shows that the material entering a Free Shop only corresponds to 0.0025 percent of the household waste disposed of in the city. This indicates that Free Shops by themselves will not solve the problem with increasing amounts of waste and emissions from increasing production. However, they can help in a small scale. / <p>20180625</p>

Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2017-05-02T13:57:50Z No. of bitstreams: 1 DissLDV.pdf: 2484486 bytes, checksum: d3e5e77576203f23208cb028dd992b41 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-05-03T13:05:04Z (GMT) No. of bitstreams: 1 DissLDV.pdf: 2484486 bytes, checksum: d3e5e77576203f23208cb028dd992b41 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-05-03T13:05:13Z (GMT) No. of bitstreams: 1 DissLDV.pdf: 2484486 bytes, checksum: d3e5e77576203f23208cb028dd992b41 (MD5) / Made available in DSpace on 2017-05-03T13:17:27Z (GMT). No. of bitstreams: 1 DissLDV.pdf: 2484486 bytes, checksum: d3e5e77576203f23208cb028dd992b41 (MD5) Previous issue date: 2016-08-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The construction sector is one of the sectors that most require natural resources and generate waste throughout the production chain. In this sense, given the need to preserve the environment and natural resources for future generations, the industry needs to improve the environmental performance of its operations chain. In order to achieve effective improvements by the actions developed by the sector, these actions need to be based on information about the environmental performance that are objective and verifiable. One of the methods that allow the collection of environmental information is Life Cycle Assessment (LCA), which is one of the main tools of environmental impact assessment for the lifecycle of products and systems. The LCA allows to evaluate the impacts of raw material extraction, manufacturing process, use and disposalt. In this context, a study of the manufacturing process of structural ceramic blocks (cradle to factory gate) was conducted, aiming to analyze its main impacts and processes that contribute most to these environmental impacts. To conduct this study data collection was performed in two plants located in the State of São Paulo. Based on data collected locally and on the international database Ecoinvent®, the life cycle inventory (LCI) was drawn up with the necessary adaptations to represent the local context. Life cycle impact assessment (LCIA) was carried out using the following methods: CML 2002, Edip 97, USEtox and IPCC 2013. Based on the LCIA results, it was possible to identify the processes that contributed to each of the impacy categories analyzed, with the electricity being the process that most contributed to all categories. But the fuel used in the burning of the blocks, in turn, did not generate significant environmental impacts due to factories studied using biomass. Therefore, this study allowed to evaluate the magnitude and importance of the environmental impacts generated by the manufacture of ceramic bricks and also to characterize the environmental performance of ceramic bricks based on LCA. / A construção civil é um dos setores que mais consome recursos naturais e gera resíduos na sua cadeia de produção. Neste sentido, diante da necessidade de preservar o meio ambiente e os recursos naturais para as futuras gerações, é fundamental que o setor melhore o desempenho ambiental de suas operações. Para que as ações desenvolvidas pelo setor resultem em melhorias efetivas, é necessário que elas sejam subsidiadas por informações sobre o desempenho ambiental, que sejam objetivas e verificáveis. Um dos métodos que permite a compilação de informações ambientais é a Avaliação de Ciclo de Vida (ACV), que se apresenta como um dos principais instrumentos de avaliação dos impactos ambientais gerados durante o ciclo de vida de produtos e sistemas. A ACV permite avaliar os impactos desde a extração de recursos naturais, processamento de matéria-prima, manufatura até o uso e descarte dos mesmos. Neste contexto, foi realizado um estudo do processo de fabricação de blocos cerâmicos estruturais (do berço ao portão da fábrica) com o intuito de averiguar seus principais impactos ambientais e os processos que mais contribuem para estes impactos. Para realizar este estudo, foi feita a coleta de dados em duas fábricas localizadas no Estado de São Paulo. Com base nos dados coletados in-loco e na base de dados internacional Ecoinvent®, o inventário do ciclo de vida (ICV) foi elaborado com as devidas adaptações para que representasse o contexto local. A partir do ICV, foi realizada a avaliação dos impactos do ciclo de vida (AICV) por meio dos métodos CML 2002, EDIP 97, USEtox e IPCC 2013. Com base nos resultados da AICV, foram identificados os processos que mais contribuíram para cada uma das categorias de impacto analisadas, sendo a eletricidade o processo que colaborou de forma mais significativa para todas as categorias. Já o combustível utilizado na queima dos blocos, por sua vez, não gerou impactos ambientais significativos, devido às fábricas estudadas utilizarem biomassa. Portanto, o presente estudo permitiu avaliar a magnitude e significância dos impactos ambientais gerados pela fabricação de blocos cerâmicos, bem como caracterizar o desempenho ambiental de blocos cerâmicos com base em ACV.

This thesis deals with modeling, simulation and implementation of Load Commutated SCR based current source Inverter (LCI) fed squirrel cage induction motor drive with sinusoidal voltage and sinusoidal current. In the proposed system, the induction motor is fed by an LCI. A three level diode clamped voltage source inverter (VSI) is connected at the motor terminal with ac chokes connected in series with it. The VSI currents are controlled in such a manner that it injects the reactive current demanded by the induction motor and the LCI for successful commutation of the SCRs in the LCI. Additionally, it absorbs the harmonic frequency currents to ensure that the induction motor draws sinusoidal current. As a result, the nature of the motor terminal voltage is also sinusoidal. The concept of load commutation of the SCRs in the LCI feeding an induction motor load is explained with necessary waveforms and phasor diagrams. The necessity of reactive compensation by the active filter connected at the motor terminal for the load commutation of the thyristors, is elaborated with the help of analytical equations and phasor diagrams. The requirement of harmonic compensation by the same active filter to achieve sinusoidal motor current and motor voltage, is also described. Finally, to achieve the aforementioned induction motor drive, the VA ratings of the active filter (VSI) and the CSI with respect to VA rating of the motor, are determined theoretically. The proposed drive scheme is simulated under idealized condition. Simulation results show good steady state and dynamic response of the drive system. Load commutation of the SCRs in the LCI and the sinusoidal profile of motor current and voltage, have been demonstrated. As in LCI fed synchronous motor drives, a special mode of operation is required to run up the induction motor from standstill. As the SCRs of the LCI are load commutated, they need motor terminal voltages for commutation. At standstill these voltages are zero. So, a starting strategy has been proposed and adopted to start the motor with the aid of the current controlled VSI to accelerate until the motor terminal voltages are high enough for the commutation of the SCRs in the LCI. The proposed drive is implemented on an experimental setup in the laboratory. The IGBT based three level diode clamped VSI has been fabricated following the design of the standard module in the laboratory. A generalized digital control platform is also developed using a TMS320F2407A DSP. Two, three phase thyristor bridges with necessary firing pulse circuits have been used as the phase controlled rectifier and the LCI respectively. Appropriate protection scheme for such a drive is developed and adopted to operate the drive. Relevant experimental results are presented. They are observed to be in good agreement with the simulation results. The effect of capacitors connected at the output of the LCI in the commutation process of the SCRs in the LCI is studied and analyzed. From the analysis, it is understood that the capacitors form a parallel resonating pair with filter inductor and the motor leakage inductance, which results in an undesired oscillation in the terminal voltage during each of the commutation intervals leading to commutation failure. So, in the final system, the capacitors are removed to eliminate any chance of commutation failure of the SCRs in the LCI. It is shown by experiment that the commutation of the SCRs takes place reliably in the absence of the capacitors also. The commutation process is studied and analyzed without the capacitors to understand the motor terminal voltage waveform of the experimental results.