Eletrônica de Potência

A design procedure is proposed for the EMC filters to be included in a three-phase/-level PWM rectifier unit in order to fulfill EMC requirements related to conducted emissions. An analytical volumetric optimization is performed considering constraints given by electrical safety, power factor and damping of resonances. The procedure avoids the necessity of applying numerical optimization allowing the analytical calculation of the total filter volume as function of rated power and switching frequency. A discussion about the limits of power density for the rectifier employing modern power semiconductors is done and optimum switching frequency of 540 kHz is calculated for a forced air-cooled system. The experimental verification of the proposed procedure is presented through CE measurements in the designed system.

Resumo-Esse artigo propõe um sistema, externo ao Veículo Elétrico (VE), capaz de adicionar funcionalidades de Vehicle-to-Home (V2H) e Vehicle-to-Grid (V2G) ao VE através do uso dos terminais da bateria disponíveis em um conector combo comercial. No caso do sistema proposto, esses terminais seriam usados para retirar energia dos veículos e entregá-la à rede ou manter a tensão na residência em caso de falta de energia. Esta configuração elimina a necessidade de conversores bidirecionais internos ao VE, reduzindo peso, custo e complexidade, adicionando também a possibilidade de integrar geração de energias renováveis locais. Para validar o conceito do sistema, são desenvolvidos o projeto e a simulação do sistema completo, assim como a construção dos conversores CC-CC utilizados no teste de um sistema de 2 kW, integrando os vários conversores de potência necessários. Palavras-Chaves-Conversores CC-CC, Full-bridge ZVS, Vehicle-to-grid, Vehicle-to-home.

Resumo-Devido ao alto nível de inserção de usinas eólicas, na rede elétrica, estão sendo requeridos pelos códigos de conexão na rede, que as modernas turbinas eólicas contribuam para a estabilidade da rede elétrica, ajustando-se a freqüência através do controle da potência ativa e a tensão através da regulação da potência reativa. Baseado neste contexto, este trabalho apresenta uma nova estratégia de controle de potência reativa utilizando uma máquina de indução de dupla alimentação, um dos tipos de geradores mais utilizados atualmente em usinas eólicas no mundo. A estrutura e o projeto da estratégia de controle desenvolvida são apresentados, assim como, os resultados experimentais obtidos em uma bancada de testes de 4kW. Palavras-Chave-controle de potência reativa, energia eólica, fontes renováveis, gerador de indução de dupla alimentação.

A review of flywheels as energy storage systems is organized in three generations. The performance is compared with that of batteries and other energy storage systems in terms of power and energy density. It is shown that a new generation, using magnetic bearings and high speeds (>60000rpm) can substitute batteries in the near future. A laboratory prototype illustrates the main parts of a 3 rd Generation flywheel.

The proposed paper presents a 500 W, universal input, wireless electric vehicle battery charging system using a non-conventional compensation topology. An algorithm to compensate Loosely Coupled Inductive Power Transfer (LCIPT) systems with such topology is explained. The design and implementation of each power converter, as well as the coils manufacturing process, is briefly covered. Experimental results are shown to validate the expected system behavior.

This paper presents a strategy for protecting high power IGCT-based converters which are currently used in a wide range of drive applications. The protection of such converters against internal faults has been addressed in the technical literature, but the main focus has been on the solutions to disconnect the converter from the mains. In this paper, the short circuit current paths through the power devices are identified and studied from the perspective of keeping the overall repair cost after a fault to a minimum. It is shown that a preferred short-circuit current path that limits the thermal energy in all IGCTs to safe levels exists. Furthermore, it is demonstrated that it is possible to guarantee, through proper busbar geometry and/or device selection, that the short-circuit current stress can always be moved to the power diodes. Simulation results are presented to support all the discussions and conclusions, avoiding the costs and risks of tests on a medium voltage prototype.

This paper presents a predictive control approach for speed control of a permanent magnet synchronous motor with trapezoidal back-electromotive force drive. The prediction model was numerically identified and considers existent transport delays in the drive. The proposed technique operates with sixstep and pulse-width modulations, which are normally used in proportional-integrative control structures. A computational cost analysis was also done. Results show improvements in speed performance, comparing to tested proportional-integral control.

In this paper is presented a bidirectional dual active clamping push-pull dc-dc converter, to be used in applications requiring isolated bidirectional interface between two dc ports with low-voltage/low-current ripple. The main characteristics of the proposed converter are the non necessity of input and output filters in both ports, galvanic isolation, reduced number of magnetic components and high efficiency operation. The paper presents a theoretical analysis of the proposed converter and experimental analysis for a 600 W prototype, with 50 kHz switching frequency, and dc power supplies of 14 and 42 volts, at the input and output ports, respectively. The measured performance agreed well with the theoretical predictions.

Shunt active power filters (SAP F) implemented without harmonic detection schemes compensate the harmonic distortion and reactive power of the load simultaneously. However, their compensation capabilities are limited by the SAP F power converter rating. Such a restriction can be minimized if the level of the reactive power demanded by the SAP F is managed. An estimation scheme for determining the filter currents is introduced to manage the level of reactive power compensation. The effectiveness of the proposed control strategy is ensured by introducing a feedforward scheme on the DC-link voltage regulation. In addition, a robust control based on adaptive pole placement with a variable structure scheme regulates the grid currents. Experimental results are shown for demonstrating the effectiveness of the proposed SAP F system.

This work present the development of an electronically controlled harmonic mitigation device with the property that it can inserts specific series harmonic impedances in the electric system. These harmonic impedances are inserted only at specific frequency (or frequencies). It can be utilized, for example, to active detune power factor capacitor banks, limiting the harmonic current through the capacitors without the need for capacitor voltage rating increase, as it does not significantly changes the fundamental voltage at the capacitors. Also the system can be used for implementation of shunt hybrid harmonic filters or be applied on distributed harmonic mitigation strategies, obtaining a flexible and cost-effective solution even for high power applications. Other advantage of the proposed system is the reduced converter rating necessary for the selective harmonic impedance implementation. The utilization of single turn secondary coaxial transformers, where the secondary side is composed only by the power system cable, for harmonic impedance coupling, gives a significant flexibility to its application, allowing an easy application on existing systems, minimizing the downtime for solution implementation and performance evaluation.

This paper presents a novel DC dynamic electronic load applied at load regulation tests of switching-mode power supplies, operating at highcurrent levels. The proposed device is based on the use of a modified Buck+Boost interleaved converter, without the use of the boost diodes, and the output filters (capacitors). Therefore, the electronic load circuitry is very simple, effective and capable to provide high pulsedcurrent levels, featuring faster rise/fall times for transient testing on high speed DC to DC converters and DC power supplies. A prototype was implemented, in order to validate the proposed structure, operating at 10V-20V DC input voltage range, 190A-290A amplitude range of the input pulsed-current (nominal value is equal to 240A±20%), with adjustable pulse-width between 4ms (adjustable time-period of 200ms) until 6ms (adjustable time-period of 350ms). The main experimental results, obtained from the implemented prototype, are presented in order to demonstrate the feasibility of the proposed dynamic electronic load, which is capable of performing experimental tests of transient load regulation for switching-mode power supplies.

This paper presents a new integration concept to generate high voltage step-up non-isolated DC/DC converters with the aid of coupled-inductors. The integration concept relies on the separation of the converter circuit into two or three parts named input, middle and output sections. Hence, any basic converter can partially or fully share one of its sections with another basic converter since both circuits comply with the integration rules. The merged converters become an integrated topology with fewer components. According to this paper, for the input section parallel integration, the circuits remaining output sections can be associated in three different ways, in a series, parallel or cascaded connection. These output sections associations allow for a merged topology to enhance their voltage gain that becomes the sum of the voltage gains of the former topologies alone. An example of integration of the boost and flyback converter is provided to illustrate the theory. The resulting integrated topologies are theoretically and experimentally evaluated. The results prove that the integration methodology is an effective way to obtain high voltage conversion ratio circuits and that the derived topologies are highly efficient due to their low converter series resistances.

This work presents some results of modeling and control design of a 30 kWp photovoltaic system connected to the grid in the Campus of Federal University of Juiz de Fora. The interface converter is connected to the grid using only the leakage inductance of a single-phase transformer bank as passive filter. The control algorithm is carried out in the synchronous reference frame (dq0). Two identical proportionalintegral controllers (PI-SRF) are designed to regulate the currents in each coordinate. It will be shown that the PI-SRF controller may have its effectiveness compromised due to distorted currents drained by the connection transformer. To overcome the aforementioned problem a repetitive controller (RC) is designed and connected in parallel with the PI-SRF. The performance of the hybrid controller (PI-SRF + RC) is tested under steady-state and transient conditions for variations in the power generated by the photovoltaic (PV) panels. Experimental results are presented to validate the design and performance of the proposed hybrid controller.

This paper proposes the analysis and design of an active-clamping coupled-inductor boost converter for high-voltage-gain applications. A buck-boost type active clamping circuit is employed in a configuration that enables the leakage energy to be recycled to the output. An accurate mathematical analysis considering the influence of the leakage and auxiliary inductances in the energy transfer process is carried out, providing the basis for the elaboration of a step-by-step design procedure. A detailed commutation analysis is also performed, describing the necessary conditions for softswitching operation. The theoretical results are experimentally verified with a 260 W, 30 V input voltage, 400 V output voltage, 100 kHz, 94.38% peak efficiency prototype.

This paper presents the deployment of a didactic workbench intended to support theoretical and practical studies addressed in subjects of undergraduate and postgraduate electrical engineering courses involving photovoltaic (PV) systems. The proposed system operates in real-time and is composed of a computational graphic interface operating in conjunction with a double-stage PV system connected to the power grid. Besides the PV array, the PV system consists of a step-up DC-DC converter, intended to track the maximum power point, and a current-controlled full-bridge inverter, intended to inject the energy produced by the PV array into the grid. The monitoring system allows to perform the following tasks: i. assist the performance evaluation of maximum power point tracking techniques tied to projects; ii. visualize the measured PV array magnitudes (voltage, current and power), as well as the estimated ones calculated from the PV array mathematical model and from the real measured values of solar irradiation and temperature; iii. analyze electric power quality indicators, based on the grid voltage and current magnitudes, and others. Experimental results are presented with the objective of testing and evaluating the versatility of the proposed didactic workbench applied in an educational environment.

This paper introduces a bridgeless boost converter based on the three-state switching cell for PFC (power factor correction) applications, whose distinct advantages are reduced conduction losses with the use of magnetic elements with minimized size, weight, and volume. The approach also employs the principle of interleaved converters, as it can be extended to a generic number of legs per winding of the autotransformers and high power levels. The theoretical analysis of the proposed converter is developed, while a comparison with the conventional boost converter is also performed. An experimental prototype rated at 1 kW is implemented to validate the proposal, as relevant issues regarding the novel converter are discussed. 1 I. INTRODUCTION

Resumo-Uma estratégia de modulação por largura de pulso (PWM) aplicada a um inversor de tensão de quatro braços é proposta neste trabalho. A técnica é utilizada para a geração de tensões trifásicas desequilibradas, incluindo a componente de sequência zero. Ela pode ser facilmente implementada em um processador digital de sinais (DSP) e com custo computacional reduzido em relação a uma estratégia de modulação tridimensional utilizada para este tipo de inversor. A técnica proposta é aplicada com um controle em malha aberta de um restaurador dinâmico de tensão (DVR) laboratorial. Os resultados de simulação e experimental são apresentados para validar a técnica proposta. Palavras-Chave-Componente de sequência zero, inversor de quatro braços, restaurador dinâmico de tensão.

Resumo-Neste artigo apresenta-se uma metodologia utilizada para projetar um conversor Ćuk de 300 W que opere como caracterizador elétrico de módulos fotovoltaicos. O protótipo projetado é de fácil operação, portátil e permite a transferência das grandezas medidas (tensão, corrente, irradiância solar e temperatura) a um computador pessoal, por meio de comunicação serial. A partir destas grandezas são traçadas as curvas I-V e P-V e extraídos os cinco parâmetros que descrevem o circuito elétrico equivalente do módulo fotovoltaico ensaiado. De posse destes parâmetros, é possível replicar o comportamento do módulo fotovoltaico em ambiente de simulação, sob quaisquer condições de irradiância solar e temperatura. A fim de validar a precisão do caracterizador desenvolvido, as curvas I-V e P-V por meio dele obtidas são comparadas com as provenientes do traçador Profitest PV, fabricado pela empresa alemã Grossen Metrawatt.

Este trabalho propõe uma topologia de UPS de dupla conversão para a integração com painéis fotovoltaicos que permite o rastreamento do ponto de máxima potência sem a adição do usual conversor CC-CC para interface entre painéis e barramento CC. Os painéis são conectados diretamente ao barramento CC, e o MPPT é realizado pelo circuito de entrada. Através deste sistema, é possível alimentar cargas com uma tensão de saída regulada, independentemente dos distúrbios da tensão da rede pública, enquanto gerando energia fotovoltaica. Em caso de energia excedente, pode-se injetar corrente na rede, uma vez que o circuito de entrada possui característica bidirecional. O desempenho do sistema é validado através de resultados Hardware-in-the-Loop, os quais demonstram a funcionalidade da topologia proposta.

Este trabalho propõe uma estrutura de controle hierárquico que permite realizar a equalização das temperaturas internas dos capacitores de barramento de UPSs conectadas em paralelo. Os capacitores eletrolíticos, usualmente utilizados em barramentos CC, são um dos principais responsáveis por falhas em sistemas de conversão de energia, sendo que a vida útil destes componentes é sensível a elevadas temperaturas de operação. Neste sentido, com o intuito de aumentar a vida útil de sistemas ininterruptos de energia conectados em paralelo, este trabalho propõe a adição de uma malha de controle que, através da medição indireta das temperaturas das UPSs, gerencia a potência ativa que cada UPS deve fornecer, a fim de equalizar as temperaturas dos capacitores. Resultados hardware-in-the-loop são adquiridos considerando duas UPSs monofásicas de 10 kVA conectadas em paralelo e localizadas em ambientes com temperaturas distintas, comprovando o bom desempenho e a viabilidade da proposta.

In this work, the inductances of an induction motor, which rotor may be misaligned, are evaluated. Two types of analysis are performed: Analytical Method (AM) and Finite Element Method (FEM). For radial displacements, both methods show equivalent results but to evaluate inductances as a function of angular displacements, only with FEM was possible to get results as with AM it would be necessary intricate functions. The inductances obtained with FEM were included in simulations of a bearingless induction motor with split windings. This approach shows a good agreement with experimental results.

This paper proposes some topologies of universal active power filter for single-phase applications with reduced number of components. Some configurations are proposed: two with both series and parallel converters connected in half-bridge, sharing the same d.c.-bus mid-point connection; and the others with the series and parallel converters sharing one leg. It will be demonstrated the existence of a coupling law between the two converters (S e and S h) related to the voltage capabilities. All configurations compensate for current and voltage harmonic and provide power factor control close to one. Comparisons between the structures are made and the steady-state analysis are also presented to demonstrate that it is possible to obtain an optimum voltage angle in order to reduce the amplitudes of the converters' currents and, consequently, the total losses of the systems. Simulated and experimental results validate the theoretical considerations.

This paper presents in detail a design methodology for Zero-Current Zero-Voltage Transition inverters with magnetically-coupled auxiliary circuit. These ZCZVT inverters accomplish favorable softswitching conditions with a magnetically coupled auxiliary voltage which is derived directly from the inverter filter inductor. It ensures no resonant auxiliary circuit, reducing circulating reactive energy. The design methodology takes into account the semiconductor requirements to ensure low switching losses on the assisted IGBT modules, which is very important to ensure the best characteristics of the ZCZVT technique. The theoretical analysis is verified experimentally by means of a 1kW, 40 kHz laboratory prototype. The results prove the high efficiency of the prototype implemented according to the proposed design.

This paper proposes a modification in both topology and operation algorithm for the existent 2/3 level converter. The modified strategy is of simple implementation. In addition, the modified topology reduces the switching losses and the command complexity. The harmonic distortion and losses of the two-level converter, the three-level Neutral-Point-Clamped (NPC) converter and the 2/3-level converter are compared. Also the limitation of the modified topology operation is investigated. Simulated and experimental results demonstrate the validity of the proposed topology and pulsewidth modulation method.

This paper approaches the study of stacked DC-DC converters with high step-up gain, using lowvoltage devices. The proposed topologies are generated from the stacking of conventional buck-boost structures and they are suitable in applications that a high conversion ratio is required. The stacked converters can also be employed as DC bus to provide one or several output voltage levels with self-balancing, and thus different loads can be connected to one or more capacitors of the stack. A generalized theoretical analysis of the proposed topologies approaching static gain, voltage and current stresses on the main components and power flow analysis is described in this paper. A 1-kW prototype with 100 V input voltage and 400 V output voltage was designed, built and tested. The experimental results corroborate the generalized theoretical analysis and they demonstrate the feasibility of the proposed converters.

Resumo-O aprimoramento da infraestrutura de carregamento dos veículos elétricos é fundamental para a sua ampla adoção. Dessa forma, este artigo propõe uma estação modular de carregamento rápido com filtro ativo de potência e elemento armazenador de energia para veículos elétricos. A estação é conectada em média tensão e composta por 10 pontos de carregamento de 60 kW cada um, em acordo com as normas vigentes para carregamento rápido. Normas as quais são inicialmente revisadas e descritas. O filtro ativo de potência é apresentado, analisado e projetado para reduzir harmônicas de corrente no ponto de conexão com a rede de distribuição primária. Além disso, é realizada a análise de estabilidade na conexão dos conversores. Os resultados experimentais no Typhoon HIL comprovam o funcionamento da estação em acordo com as exigências normativas internacionais.

This paper describes the analysis and design of an electronic ballast devised to drive both, high pressure sodium vapor (HPS) and high pressure mercury vapor (HPMV) lamps, in dimmed operation with no need of parameter modification. The main objective is to achieve weight and volume reduction of a public lighting components bench test equipment, used to perform basic operational tests in a Brazilian electric utility company. Specifically, the analysis, design and implementation of an electronic ballast, based on a series-parallel loaded resonant inverter, for 70 W HPS and 125 W HPMV lamps testing is presented. Experimental results from a lab prototype, performing high intensity discharge (HID) lamp tests in dimmed operation and no discharge arc instability, evidences the feasibility of the proposed ballast concerning the intended application.

Resumo-Este artigo apresenta uma topologia de conversor de estado sólido caracterizado por permitir a conversão direta ca-ca por meio de um barramento alternado modulado em alta frequência. Tal topologia é obtida a partir de um conversor em ponte completa e de um em meia ponte, interligados pelos pontos intermediários dos braços, via transformador de alta frequência. O acionamento do conversor é realizado empregando-se modulação por deslocamento de fase, sendo que a potência transferida entre as portas é controlada pelo ângulo de defasagem entre os comandos dos interruptores de cada ponte. Além de permitir fluxo bidirecional de potência, a topologia possibilita a utilização da indutância de dispersão do transformador como elemento de transmissão de energia e requer reduzido número de componentes passivos. Por estas características, torna-se vantajosa quando aplicada em redes inteligentes. A validação da operação do conversor proposto é realizada tanto por simulação quanto experimentalmente, a partir de um protótipo de 600 VA.

Resumo-Com a crescente demanda por energia elétrica, os sistemas HVDC tendem a assumir um papel cada vez mais importante no cenário mundi al. No entanto, a extração ou injeção de pequenos bl ocos de energia ao long o de linhas HVDC constitui-se em um problema bastante complexo, devi do a sua característica de transmissão ponto-a-ponto. Este estudo apresenta uma nova topologia para o Tap HVDC, bi direcional em energia, permitindo a conexão tanto de consumi dores quanto de geradores ao sistema HVDC, de forma a realizar intercâmbi o de energia com este. A fi m de comprovar a eficiência do equi pamento no que se refere ao dreno e a injeção de potênci a ao longo da linha, modelou-se um sistema simplificado no qual o Tap terá seus terminais conectados a uma fonte de corrente e ao potencial de terra. A ferramenta computaci onal utilizada para simulação foi o software de transitórios eletromagnéticos PSCAD/ EMTDC.

Resumo: 1 Nos últimos anos têm surgido normas e legislações que recomendam ou regulam o consumo de energia no modo de espera, ou standby. Este artigo refere-se ao estudo de aparelhos de TV e analisa aspectos do impacto do consumo no modo standby em termos energéticos, econômicos e ambientais. A partir de medições em diferentes aparelhos de TV verifica-se a ampla variação no consumo no modo de espera, indicando-se também a possibilidade de redução destas perdas, com manutenção do desempenho do aparelho. Faz-se também uma discussão das tecnologias eletrônicas de potência disponíveis para redução deste consumo. A análise feita indica uma redução de demanda de 6,32MW, uma economia anual de 40,2 GWh, evitando-se uma emissão equivalente de 19,3 GgCO 2 , supondo a imposição de normas que exijam um consumo de standby de até1 W.

Resumo-Este artigo apresenta o conversor CC-CC bidirecional em corrente (Elevador/abaixador) com comutação suave ZVZCS (zero voltage zero current switching) e grampeamento ativo, utilizando um único interruptor auxiliar. As perdas em comutação são reduzidas através da implementação de um circuito snubber ativo, o qual provê comutação sob tensão nula (ZVS) na entrada em condução de todos os interruptores e também no bloqueio do interruptor auxiliar. O bloqueio do interruptor principal ocorre com comutação sob corrente nula (ZCS). Dentre as suas principais características estão robustez, baixo peso e volume e alta eficiência. O principio de operação em regime permanente, análise matemática, simulação numérica e resultados experimentais de um protótipo de laboratório são apresentados.

Resumo-Este trabalho propõe uma técnica de controle híbrida Proporcional Integral-Linear Quadratic Gaussian (PI-LQG) para o Static Synchronous Compensator (STATCOM). Na técnica proposta, adiciona-se o filtro de Kalman ao controlador Linear Quadratic Regulator (LQR) com ação integral, formando o controlador LQG, tal combinação torna o sistema mais robusto e menos suscetível a ruídos de processo e de medição. Ao se utilizar um controlador híbrido, as matrizes de ponderação para projetar os ganhos do controlador LQR e do filtro de Kalman são de menor ordem, facilitando a sintonia dos controladores. Para a validação da técnica proposta, são utilizadas duas técnicas de controle para comparação: PI tradicional e PI-LQR com ação integral. Os resultados são obtidos via simulação, no software PSIM, e experimentalmente.

This paper proposes a network communication system applied in a control strategy for parallel-connected multi-inverters, which is based on a distributed control system and a redundant communication system. The control system is produced by a Phased-Locked Loop (PLL) synchronism algorithm, a voltage controller and a parallelism controller. All control systems are based on instantaneous values and in the parallelism control the inverters share a single voltage reference signal. The communication system, which is the main focus of the paper, is based on two buses: one analog, which is a measurement taken from the electrical grid; and one digital, comprised of a Controller Area Network (CAN). The former allows the reference voltage of all inverters to be in synchronism and the latter keeps the reference voltage in synchronism even during a grid power outage. There is a PLL algorithm in each Voltage Source Inverter (VSI), which ensures the synchronism between the internal reference and external signal received from the grid or from the CAN. The proposed networked control system was verified in three 5 kVA three-phase VSIs operating in parallel. Experimental results with static and dynamic tests and with electrical grid interruption and return, were obtained. The networked control system is redundant and it provides increased reliability, thus it can be applied in the parallel operation of an on-line Uninterruptible Power Supply (UPS).

This article describes an automation system for a residues treatment plant based on thermal plasma. A compact PLC was used to activate several subsystems and to control the main reactor inner temperature using Fuzzy logic. A human-machine interface allows the monitoring of the variables and the activations of devices of the system remotely. An OPC communication is used to link the computer and the PLC.

Existing Zero-Current Transition and Zero-Current Zero-Voltage Transition inverters provides favorable switching conditions for IGBT semiconductors increasing significantly the reactive energy of the converter. This situation offset the benefits accomplished by abovementioned soft-switching techniques. This paper presents a novel family of Zero-Current Zero-Voltage Transition inverters that overcome this problem by using no resonant tank in the auxiliary circuit. It accomplishes the favorable soft-switching conditions with a magnetically coupled auxiliary voltage source which is derived directly from the inverter filter inductor. Theoretical analysis of the inverter operation is presented and it is verified experimentally from a 1kW, 40kHz, laboratory prototype. The obtained experimental results prove the reliability of the proposed family of ZCZVT inverters.

This paper presents the grid connected mode of a 3 kVA single-phase uniterruptible power supply (UPS), with features of low frequency operation, high efficiency and unit power factor of the input. The input stage of the proposed UPS is composed by a power factor correction rectifier based on classical boost converter, which is used to supply the dc bus. The output stage is composed by a multilevel inverter, which is based on a low frequency full-bridge converter associate to a multiple winding transformer with one primary coil and several secondary coils. Each secondary coil is used to produces the partial alternating voltage and the series combination of the output coils are used to generating the complete output voltage. The theoretical analysis, design example, as well as experimental results of the proposed UPS system are presented in this paper.

Resumo-Este trabalho tem por objetivo analisar o modelo do gerador de indução duplamente alimentado no referencial dq síncrono através de estudo teórico. Através da análise dos circuitos que relacionam o rotor e o estator desta máquina nos eixos direto e em quadratura, um modelo matemático em malha fechada será deduzido e analisado em detalhes. Um desenvolvimento matemático baseado em controladores proporcional e proporcionalintegral será proposto. Por fim, resultados experimentais a partir de um protótipo de 8 kW montado em laboratório, onde o comportamento dos controladores diante de variações em degrau na referência de corrente do rotor tanto no eixo direto quanto no eixo em quadratura serão apresentados e discutidos, a fim de validar a teoria proposta.

Resumo ⎯ Este trabalho analisa a compensação de correntes harmônicas através de um filtro ativo híbrido. No presente estudo, o filtro híbrido consiste de um filtro ativo conectado em paralelo com o indutor de um filtro passivo sintonizado. O objetivo deste arranjo é operar com menores tensão e corrente a serem processadas pelo filtro ativo. O artigo investiga o comportamento do filtro híbrido na compensação de correntes harmônicas, a partir de uma estratégia de controle usada no filtro ativo e discute o dimensionamento do inversor. Resultados de simulação e experimentais verificam a operação do sistema.

Resumo-Este trabalho apresenta o projeto de um controlador multimalhas para utilização em um inversor monofásico e também o controle do acionamento de uma chave estática de transferência (STS-Static Transfer Switch), ambos aplicáveis em UPS (Uninterruptible Power Supplies). Duas malhas de realimentação são utilizadas no controle do inversor, uma malha interna de corrente e outra externa de tensão. Controladores do tipo proporcional-ressonante atuam como compensadores em ambas as malhas. O atraso da resposta dinâmica do modulador PWM (Pulse Width Modulation) digital é considerado no projeto dos controladores, uma vez que é um fator que limita os ganhos dos compensadores. Uma topologia da STS é proposta, composta de IGBTs (Insulated Gate Bipolar Transistor) e diodos em substituição a convencional, de tiristores, obtendo-se uma redução significativa no tempo de transferência da alimentação de uma carga crítica da rede elétrica para uma fonte auxiliar (inversor monofásico). A estratégia de controle para o acionamento da STS é baseada no método de detecção do valor de pico do sinal de tensão utilizando um algoritmo de PLL (Phased Locked Loop). Resultados experimentais comprovam o bom desempenho do controlador multimalhas e também do rápido tempo de transferência da chave estática.

This paper introduces a new family of nonisolated dc-dc converters that are generated by the integration of the active switched-capacitor (ASCC) and the conventional commutation cell (CCC). Based on the commutation cell concept, the new conceived hybrid active commutation cell (HACC) provides three different types of hybrid converters: buck, boost and buck-boost. All three converters are investigated in this study through the following approaches: topological stages, static gain analysis considering the switched-capacitor features, generalization of the HACC and gain for M cells and steady-state analysis. The buck version presents a high conversion rate, which demonstrates that it has potential for step-down applications. To verify the proposed topologies, a prototype was built with the following specifications: 600 V input voltage, 150 V output voltage, 70 kHz switching frequency and 1 kW rated power. Efficiency close to 95% was obtained at 1 kW for the buck topology, which demonstrates that the proposed HACC can provide gain and high efficiency at the same time.

This paper presents an insulated auxiliary power source with multiple outputs based on a two-stage structure, where the first-stage operates as a controlled current source and the second-stage as an active rectifier. The second-stage is replicated for each load, where the output voltage is independently controlled by a hysteresis band controller integrated to the auxiliary power source's circuit. Insulation between the multiple stages is achieved by a medium-frequency transformer for each output. The main aim of this auxiliary power supply is to feed modular multilevel converters in laboratory applications that run at the lower range of medium-voltage dc. Theoretical analysis of the auxiliary power supply is presented and verified experimentally for the converter's two main modes of operation.

This paper presents a strategy to reduce the current of the healthy phases for brushless DC motors (BLDC) in open-phase fault, avoiding the degradation of the motor and allowing the safe shutdown. After an openphase fault diagnosis, through an algorithm capable of detecting and identifying faults and phase returns of the BLDC motor in real time, a corrective action divided in three-steps is proposed. First, the traditional 120 • Six-Step operating method is changed for a switching

This paper presents the study and development of a single stage three-port non-isolated DC-DC converter, suitable for PV integration to the grid or isolated systems. The proposed topology uses a boost Artigo submetido em 20/10/2016. Primeira revisão em 22/12/2016. Aceito para publicação em 05/03/2017 por recomendação do Editor Marcelo Cabral Cavalcanti. converter with high voltage gain based on bidirectional three state switching cell. It allows the connection of a battery bank, a set of photovoltaic panels and the dc link of a inverter in a single stage of processing. The bidirectional characteristic of the proposed topology allows photovoltaic panels charge the battery bank and supply the load depending on sunlight while providing a variable dc link to an inverter. Another important feature of this converter is the soft switching in ZVS mode for all switches. A 500W experimental prototype was developed in order to validate all the theoretical analysis. The developed converter was ...

This work aims at the design of a roped elevator prototype, which uses a linear induction motor (LIM) as a traction machine. It is also concerned with the development of a specific inverter to feed the linear motor that allows several ways to drive the elevator through a suitable choice of the RMS voltage levels, angular phase displacement and electrical frequency of the output voltage. The result tries to establish a new concept for elevators through a new construction technique and assembly of the system with counterweight, which increases the reliability and comfort with cost reduction.