Indiana University-Purdue University Indianapolis (IUPUI) / The substantial increase demand for electrical energy requires high efficient apparatus dealing with energy conversion. Several technologies have been suggested to implement power supplies with higher efficiency, such as multilevel and interleaved converters. This thesis proposes an energy conversion unit with an optimized number of output voltage levels per number of switches nL=nS. The proposed five-level four-switch per phase converter has nL=nS=5/4 which is by far the best relationship among the converters presented in technical literature. A comprehensive literature review on existing five-level converter topologies is done to compare the proposed topology with conventional multilevel converters. The most important characteristics of the proposed configuration are: (i) reduced number of semiconductor devices, while keeping a high number of levels at the output converter side, (ii) only one DC source without any need to balance capacitor voltages, (iii) high efficiency, (iv) there is no dead-time requirement for the converters operation, (v) leg isolation procedure with lower stress for the DC-link capacitor. Single-phase and three-phase version of the proposed converter is presented in this thesis. Details regarding the operation of the configuration and modulation strategy are presented, as well as the comparison between the proposed converter and the conventional ones. Simulated results are presented to validate the theoretical expectations. In addition a fault tolerant converter based on proposed topology for micro-grid systems is presented. A hybrid pulse-width-modulation for the pre-fault operation and transition from the pre-fault to post-fault operation will be discussed. Selected steady-state and transient results are demonstrated to validate the theoretical modeling.

As fontes renováveis de energia, em especial a energia solar fotovoltaica vem ganhando espaço nos últimos anos devido ao avanço da tecnologia, redução dos custos e redução das fontes não-renováveis. Os painéis fotovoltaicos isoladamente ou para pequenas aplicações geram uma baixa tensão de saída e a adequação dos níveis de tensão fornecidos em sua saída aos requeridos pela concessionária de energia elétrica é um desafio. Neste trabalho é apresentada uma nova estrutura modificada da topologia do conversor SEPIC que usa as técnicas de acoplamento magnético série e células multiplicadoras de tensão em conjunto, afim de obter um elevado ganho de tensão, visando a aplicação em fontes renováveis de energia. Optou-se pela solução não isolada, pois esta apresenta diversas vantagens em relação a solução isolada, como: menor peso, volume, custo e maior eficiência energética devido a menores perdas de potência nos indutores acoplados. Também, a utilização da indutância de dispersão, que é um parâmetro intrínseco de um acoplamento magnético, permite a operação com comutação suave ZCS (ZCS, do inglês Zero Current-Switching) no interruptor, aumentando a eficiência da estrutura com a redução das perdas por comutação. No decorrer do trabalho são realizadas as análises das etapas de operação de diversos conversores a partir do conversor SEPIC modificado, evolui-se pela adição de técnicas elevadoras de tensão até a estrutura proposta neste trabalho. Por fim, é realizado o controle em malha fechada utilizando um controlador PID analógico que fornece uma resposta rápida e consequente correção a possíveis mudanças na variável controlada. Os resultados teóricos e experimentais do conversor proposto são descritos neste trabalho para validar as análises desenvolvidas e demonstrar a eficiência da estrutura. O protótipo é desenvolvido para uma aplicação com potência nominal de 200 W, tensão nominal de saída igual a 450 V e uma tensão de entrada variando entre 20 V e 40 V. O rendimento obtido para o conversor proposto operando na frequência de 35 kHz na potência nominal é de 91,28% e eficiência igual a 89,04% para a potência nominal de 200 W na frequência de 90 kHz. / The renewable energy resources, in special the photovoltaic energy has been achieve more space in last years due to technology advances, cost reduction and decrease of the non-renewable energy sources. The photovoltaic panels in isolation or to small applications generate a low output voltage and to comply with of voltage levels provided in panel’s output to those required by electric power concessionaire is a challenge. In this work is presented a new structure modified of the SEPIC converter topology who uses the coupling magnetic series and voltage multiplier cell techniques together, in order to obtain a high voltage gain aiming at application in renewable energy resources. It was has been choosen non-isolated solution, because this present several advantages in relation to the isolated solution, such as: lower weight, volume, cost and high energy efficiency due to smaller power losses in the coupled inductors. The use leakage inductance, who is an intrinsic parameter of the a magnetic coupling, allows soft-switching operation ZCS in switch, increasing the structure’s efficiency with reduction of switching losses. During the work are perform the analysis of the operation steps of several converters as of the modified SEPIC converter and evolves by addition high voltage techniques until the structure proposed in this work. Finally, is performed the closed loop control using the analog PID controller who provides a fast response and consequent correction to possible changes in the controlled variable. The theoretical and experimental results of the proposed converter are described in this work to validate the developed analysis and demonstrate the structure’s efficiency. The prototype is developed to a application with nominal power of 200 W, nominal output voltage equal 450 V and an input voltage varying between 20 V and 40 V. The efficiency obtained to proposed converter operating in frequency of the 35 kHz in nominal power is 91,28% and efficiency equal 89,04% to nominal power in frequency of the 90 kHz.

FUMDES/UNIEDU; FITEJ; / Este trabalho apresenta a concepção de estruturas eletrônicas que podem ser utilizadas para a leitura de tensão e de corrente em conversores estáticos de energia, chaveados ou não, que trabalham em frequências superiores a 100 kHz, em especial as frequências eletrocirúrgicas (300 kHz..5 MHz). Além das estruturas de leitura, também a potência instantânea e a potência ativa são determinadas de forma analógica, possibilitando o futuro desenvolvimento de um sistema de controle da potência ativa de saída de um equipamento eletrocirúrgico. O objetivo é apresentar uma estrutura cuja reatância seja desprezível na faixa de frequências considerada, ou cujo efeito possa ser compensado, possibilitando a criação de circuitos amostradores de sinais complexos, de alta frequência, com um baixo custo de implementação, e usar estas amostras para determinar a potência ativa entregue. Um breve estudo das características reais dos resistores axiais de sinal (resistores com corpo cilíndrico, revestido por um filme de carbono ou filme metálico e com fixação por terminais através de furos na placa de circuito impresso, do inglês Pin Through Hole - PTH), de superfície (Surface Mounted Device - SMD) e resistores de potência de fio também é apresentado. Em seguida, dois modelos simplificados, porém realísticos, são apresentados, sendo um para resistências inferiores a 100 Ohms (Ω) e outro para resistências superiores a 100 Ω. Na sequência, um sistema analógico que realiza a amostragem dos sinais de tensão e de corrente de saída é proposto, bem como um sistema que determina a potência ativa em tempo real. Cada sistema é desenvolvido e testado individualmente, sendo que os resultados validados de um estágio são utilizados para aferir a eficácia do estágio subsequente. Ao final, o conjunto é testado, por meio de uma sequência de ensaios, cujos resultados são analisados e as considerações acerca do sistema como um todo são apresentadas, enfatizando que o erro máximo no cálculo da potência ativa ficou abaixo de 20%, como exige a norma NBR IEC 60601-2-2, assim como o baixo custo de implementação foi alcançado. Por fim, estes resultados mostram uma maneira viável de implementar um sistema de medição de potência ativa para saídas de equipamentos eletrocirúrgicos. / This work presents the design of electronic structures that can be used for voltage and current probing in static power converters, switched or not, which work at frequencies above 100 kHz, in particular electrosurgical frequencies (300 kHz..5 MHz). In addition, also the instantaneous power and the active power are determined analogically, allowing the development of a control system that stabilizes active output power of an electrosurgical unit. The purpose of this work is to find a structure with neglectable reactance in the frequency band considered, or compensate them, creating low cost sampler circuits for complex high frequency signals. A brief study of Pin Through Holes (PTH) signal resistors, Surface Mounted Devices (SMD) signal resistor, and power wire resistors above 100 Ω characteristics is presented. Two realistic simplified models are proposed. One for signal resistances lower than 100 Ω and power wire resistors lower than 100 Ω. Another one for signal resistance greater than 100 Ω. Further, an analog system for reading the output voltage and current are proposed as well as one for real time active power determination. Each system is individually designed and tested. Validated results of one stage are used to assess the effectiveness of the subsequent stage. In the end, the full circuit is tested, and the results are analyzed demonstrating that a lower than 20% error is achieved as well as the low implementation cost. Finally, these results show a way to implement an active power measurement system for electrosurgical units that is unprecedented up to now.

O presente trabalho tem por objetivo o desenvolvimento de um modelo analógico dinâmico do IGBT 2MBI1200U4G-170 para simulação SPICE para a análise de tempos de comutação, perdas e corrente de carga. Este desenvolvimento foi motivado pelo fato de não se dispor de modelos prontos para IGBT para faixas de tensão e corrente na ordem de kV e kA, destinado ao projeto de um conversor CC para controle de motores de tração em locomotivas diesel-elétricas. Como parte do processo se fez uma tentativa de modificação do modelo padrão de IGBT da plataforma Cadence Orcad 16.5, baseada nos trabalho de Hefner, considerada uma forma de modelo físico. Verificou-se que o correto levantamento dos dados para o modelo físico não seria compensatório frente às análises desejadas, o que gerou necessidade por outras formas de modelagem. Decidiu-se por um modelo analógico, obtido com dados do catálogo do componente descritos em tabelas e como fontes de tensão e corrente. Os resultados mostraram-se adequados para projeto térmico, análise de formas de onda e corrente de porta e coletor. A simulação é comparada com curvas da documentação do fabricante e com dados obtidos a partir de testes estáticos em laboratório com duas topologias. Testes foram feitos com tensão de entrada de 74V, 300V, 900V e 1000V, frequências de comutação de 200Hz, 416Hz, 1kHz e 2kHz e correntes de carga de até 1400A. A corrente de carga apresentou diferenças de até 3% com a medida em laboratório e a temperatura divergiu em até 7% com a medida no dissipador do protótipo usado. / This paper presents the design report for an analog IGBT SPICE model, part number 2MBI1200U4G-170. The modeling was perceived as a interesting tool in order to analyze the switching times and losses during the development, not performed at the University, of a chopper DC-DC converter used for current control of traction motors of diesel-electric locomotives. The main motivational factor was that an practical and quick approach was wanted and none standard model was found for the intended IGBT part number. As part of the process, an attempt to modify the standard SPICE model of the Cadence Orcad 16.5, which is a physics model based on Hefner works, was made. It was verified that the correct data collecting for the standard model would not be compensatory, so other modeling techniques were needed. It was decided an analog modeling would be used. The modeling achieved uses no more than the information found on the component datasheet described in tables format, voltage and current sources. The validation was done in two different topologies with load currents up to 1400A, switching frequencies of 200Hz, 416Hz, 1kHz and 2kHz and input voltages of 74V, 300V, 900V and 1000V . Comparatives were done with the vendor catalog and laboratory data. The model is satisfactory for heat, collector and gate currents analysis. The simulation current and temperature results showed differences up to 3% and 7%, respectively, when compared to laboratories measurements.

FUMDES/UNIEDU; FITEJ; / Este trabalho apresenta a concepção de estruturas eletrônicas que podem ser utilizadas para a leitura de tensão e de corrente em conversores estáticos de energia, chaveados ou não, que trabalham em frequências superiores a 100 kHz, em especial as frequências eletrocirúrgicas (300 kHz..5 MHz). Além das estruturas de leitura, também a potência instantânea e a potência ativa são determinadas de forma analógica, possibilitando o futuro desenvolvimento de um sistema de controle da potência ativa de saída de um equipamento eletrocirúrgico. O objetivo é apresentar uma estrutura cuja reatância seja desprezível na faixa de frequências considerada, ou cujo efeito possa ser compensado, possibilitando a criação de circuitos amostradores de sinais complexos, de alta frequência, com um baixo custo de implementação, e usar estas amostras para determinar a potência ativa entregue. Um breve estudo das características reais dos resistores axiais de sinal (resistores com corpo cilíndrico, revestido por um filme de carbono ou filme metálico e com fixação por terminais através de furos na placa de circuito impresso, do inglês Pin Through Hole - PTH), de superfície (Surface Mounted Device - SMD) e resistores de potência de fio também é apresentado. Em seguida, dois modelos simplificados, porém realísticos, são apresentados, sendo um para resistências inferiores a 100 Ohms (Ω) e outro para resistências superiores a 100 Ω. Na sequência, um sistema analógico que realiza a amostragem dos sinais de tensão e de corrente de saída é proposto, bem como um sistema que determina a potência ativa em tempo real. Cada sistema é desenvolvido e testado individualmente, sendo que os resultados validados de um estágio são utilizados para aferir a eficácia do estágio subsequente. Ao final, o conjunto é testado, por meio de uma sequência de ensaios, cujos resultados são analisados e as considerações acerca do sistema como um todo são apresentadas, enfatizando que o erro máximo no cálculo da potência ativa ficou abaixo de 20%, como exige a norma NBR IEC 60601-2-2, assim como o baixo custo de implementação foi alcançado. Por fim, estes resultados mostram uma maneira viável de implementar um sistema de medição de potência ativa para saídas de equipamentos eletrocirúrgicos. / This work presents the design of electronic structures that can be used for voltage and current probing in static power converters, switched or not, which work at frequencies above 100 kHz, in particular electrosurgical frequencies (300 kHz..5 MHz). In addition, also the instantaneous power and the active power are determined analogically, allowing the development of a control system that stabilizes active output power of an electrosurgical unit. The purpose of this work is to find a structure with neglectable reactance in the frequency band considered, or compensate them, creating low cost sampler circuits for complex high frequency signals. A brief study of Pin Through Holes (PTH) signal resistors, Surface Mounted Devices (SMD) signal resistor, and power wire resistors above 100 Ω characteristics is presented. Two realistic simplified models are proposed. One for signal resistances lower than 100 Ω and power wire resistors lower than 100 Ω. Another one for signal resistance greater than 100 Ω. Further, an analog system for reading the output voltage and current are proposed as well as one for real time active power determination. Each system is individually designed and tested. Validated results of one stage are used to assess the effectiveness of the subsequent stage. In the end, the full circuit is tested, and the results are analyzed demonstrating that a lower than 20% error is achieved as well as the low implementation cost. Finally, these results show a way to implement an active power measurement system for electrosurgical units that is unprecedented up to now.

O presente trabalho tem por objetivo o desenvolvimento de um modelo analógico dinâmico do IGBT 2MBI1200U4G-170 para simulação SPICE para a análise de tempos de comutação, perdas e corrente de carga. Este desenvolvimento foi motivado pelo fato de não se dispor de modelos prontos para IGBT para faixas de tensão e corrente na ordem de kV e kA, destinado ao projeto de um conversor CC para controle de motores de tração em locomotivas diesel-elétricas. Como parte do processo se fez uma tentativa de modificação do modelo padrão de IGBT da plataforma Cadence Orcad 16.5, baseada nos trabalho de Hefner, considerada uma forma de modelo físico. Verificou-se que o correto levantamento dos dados para o modelo físico não seria compensatório frente às análises desejadas, o que gerou necessidade por outras formas de modelagem. Decidiu-se por um modelo analógico, obtido com dados do catálogo do componente descritos em tabelas e como fontes de tensão e corrente. Os resultados mostraram-se adequados para projeto térmico, análise de formas de onda e corrente de porta e coletor. A simulação é comparada com curvas da documentação do fabricante e com dados obtidos a partir de testes estáticos em laboratório com duas topologias. Testes foram feitos com tensão de entrada de 74V, 300V, 900V e 1000V, frequências de comutação de 200Hz, 416Hz, 1kHz e 2kHz e correntes de carga de até 1400A. A corrente de carga apresentou diferenças de até 3% com a medida em laboratório e a temperatura divergiu em até 7% com a medida no dissipador do protótipo usado. / This paper presents the design report for an analog IGBT SPICE model, part number 2MBI1200U4G-170. The modeling was perceived as a interesting tool in order to analyze the switching times and losses during the development, not performed at the University, of a chopper DC-DC converter used for current control of traction motors of diesel-electric locomotives. The main motivational factor was that an practical and quick approach was wanted and none standard model was found for the intended IGBT part number. As part of the process, an attempt to modify the standard SPICE model of the Cadence Orcad 16.5, which is a physics model based on Hefner works, was made. It was verified that the correct data collecting for the standard model would not be compensatory, so other modeling techniques were needed. It was decided an analog modeling would be used. The modeling achieved uses no more than the information found on the component datasheet described in tables format, voltage and current sources. The validation was done in two different topologies with load currents up to 1400A, switching frequencies of 200Hz, 416Hz, 1kHz and 2kHz and input voltages of 74V, 300V, 900V and 1000V . Comparatives were done with the vendor catalog and laboratory data. The model is satisfactory for heat, collector and gate currents analysis. The simulation current and temperature results showed differences up to 3% and 7%, respectively, when compared to laboratories measurements.

Experimental research on high-power converters, particularly in an academic environment, faces severe infrastructural constraints. Usually, power source and loads of required ratings are not available. Further, more importantly, the energy consumption is huge. One possibility is to establish an experimental research platform, comprising of a network of high-power converters, through which power is circulated and which draws only the losses from the mains. This work deals with the establishment of a circulating power test set-up, comprising of two line-side PWM converters, inclusive of control and modulation methods for the two converters. Two types of circulating power test setups are developed. In the first setup, the converters are connected in parallel, on ac as well as dc sides, such that real and/or reactive power is circulated between them. In the second test setup, the dc buses of the converters are separated; hence, only reactive power circulation is possible. These setups are used to conduct heat-run tests with low energy expenditure on the PWM converters at various operating conditions up to power levels of 150 kVA. Further, these are used to validate analytically-evaluated thermal characteristics of high-power PWM converters. A safe thermal limit is derived for such converters in terms of apparent power (kVA) handled, power factor and switching frequency. The effects of voltage sag and of unequal current sharing between parallel IGBT modules on the safe thermal limit are studied. While the power drawn by the circulating-power setup from the grid is much lower than the ratings of the individual converters, the harmonic injection into the mains by the setup could be significant since the harmonics drawn by both converters tend to add up. This thesis investigates carrier interleaving to improve the waveform quality of grid current, drawn by the circulating-power test setup. The study of carrier interleaving is quite general and covers various applications of parallel-connected converters such as unity power factor rectification, static reactive power compensation and grid-connected renewable energy systems. In literature, carrier interleaving has been employed mainly for unity power factor rectifiers, sharing a common dc load equally. In such case, the fundamental components of the terminal voltages of the parallel converters are equal. However, when the power sharing between the two converters is unequal, or when power is circulated between the two converters, the terminal voltages of the two converters are not equal. A method to estimate rms grid current ripple, drawn by parallel-connected converters with equal and/or unequal terminal voltages, in a synchronous reference frame is presented. Further, the influence of carrier interleaving on the rms grid current ripple is studied. The optimum interleaving angle, which minimizes the rms grid current ripple under various applications, is investigated. This angle is found to be a function of modulation index of the converters in the equal terminal voltages case. In the unequal terminal voltages case, the optimum interleaving angle is shown to be a function of the average modulation index of the two parallel converters. The effect of carrier interleaving is experimentally studied on the reactive power circulation setup at different values of kVA and different dc bus voltages. The grid current ripple is measured for different values of interleaving angle. It is found experimentally that the optimum interleaving angle reduces the rms grid current ripple by between 37% and 48%, as compared without interleaving, at various operating conditions. Further, the reactive power circulation test set-up is used to evaluate and compare power conversion losses corresponding to different PWM techniques such as conventional space-vector PWM (CSVPWM), bus-clamping PWM (BCPWM) and advanced bus-clamping PWM methods for static reactive power compensator (STATCOM) application at high power levels. It is demonstrated theoretically as well as experimentally that an advanced bus-clamping PWM method, termed minimum switching loss PWM (MSLPWM), leads to significantly lower power conversion loss than CSVPWM and BCPWM techniques at a given average switching frequency.

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis proposes a family of non-isolated bidirectional converter in order to interface dc and ac variables. Such power electronics solutions guarantee: (i) bidirectional power flow between dc and ac converter sides, (ii) independent control in both converter sides, (iii) high level of integration with a reduction of one power switch and its drive circuits, (iv) implementation of two functions by using a unique power conversion stage and (v) reduction of the capacitor losses. Despite proposing new power converter solutions, this thesis presents an analysis of the converters in terms of pulse-width-modulation (PWM) strategy, dc-link capacitor variables, and suitable a control approach. Solutions for single-phase, three-phase and three-phase four-wire systems are proposed by employing a converter leg with three switches. A possible application of this converter is in Vehicle-to-Grid (V2G) systems and interfacing dc microgrid with a utility grid. In addition to the new power electronics converters proposed in this thesis, an experimental setup has been developed for validation of the simulated outcomes. The proof-of-concept experimental setup is constituted by: DSP, Drivers & Integrating Board, Power Supply and, Power Converter & Heat-Sink .

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents a converter topology for photovoltaic panels. This topology minimizes the number of switching devices used, thereby reducing power losses that arise from high frequency switching operations. The control strategy is implemented using a simple micro-controller that implements the proportional plus integral control. All the control loops are closed feedback loops hence minimizing error instantaneously and adjusting efficiently to system variations. The energy management between three components, namely, the photovoltaic panel, a battery and a DC link for a microgrid, is shown distributed over three modes. These modes are dependent on the irradiance from the sunlight. All three modes are simulated. The maximum power point tracking of the system plays a crucial role in this configuration, as it is one of the main challenges tackled by the control system. Various methods of MPPT are discussed, and the Perturb and Observe method is employed and is described in detail. Experimental results are shown for the maximum power point tracking of this system with a scaled down version of the panel's actual capability.

Indiana University-Purdue University Indianapolis (IUPUI) / This research proposes state-of-the-art multilevel converter topologies and their modulation strategies, the implementation of a conventional flying-capacitor converter topology up to four-level, and a new four-level flying-capacitor H-Bridge converter confi guration. The three phase version of this proposed four-level flying-capacitor H-Bridge converter is given as well in this study. The highlighted advantages of the proposed converter are as following: (1) the same blocking voltage for all switches employed in the con figuration, (2) no capacitor midpoint connection is needed, (3) reduced number of passive elements as compared to the conventional solution, (4) reduced total dc source value by comparison with the conventional topology. The proposed four-level capacitor-clamped H-Bridge converter can be utilized as a multilevel inverter application in an electri fied railway system, or in hybrid electric vehicles. In addition to the implementation of the proposed topology in this research, its experimental setup has been designed to validate the simulation results of the given converter topologies.