The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE-519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed "half-controlled" boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE–519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed “half-controlled” boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE–519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed “half-controlled” boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE-519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed "half-controlled" boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

A high efficiency driver is designed for light emitting diode (LED) street lamps in the thesis. The main power conversion circuit employs a phase-controlled rectifier to convert the power from the ac mains of 110/220 V, 60 Hz directly into a dc source, providing the required output current for the street lamps formed by arrayed high brightness white LEDs. The phase-controlled rectifier of the LED driver circuit can be a conventional semi-converter or a rectifier with symmetrical phase control, which makes use of thyristors and power transistors, respectively, to regulate the LED current by means of adjusting the conduction angles in a cycle of the ac line. The phase-controlled rectifiers may exclude the use the bulky electrolyte capacitor with acceptable variation in the chromaticity and the color temperature. Operating at the low frequency, the phase-controlled rectifiers can avoid the problems of electromagnetic interference caused by high-frequency switching and adopt low cost power switches. Furthermore, a relatively high power factor can be achieved when the line source voltage varies within a small allowable range. The research is targeted to a design of a 200 W LED street lamp. To facilitate the changes of the control functions and circuit parameters, the control circuit is realized with a microcontroller. In addition, over-voltage/current protections can be included easily. Experimental results demonstrate that the phase-controlled rectifiers with appropriately designated circuit parameters can approach a power factor of 0.92 and a circuit efficiency of 93% at the rated output.

Existing models describing the dynamic behavior of a six-pulse rectifier during a short-circuit fault condition are derived from switch models using time-domain average value parametric functions. Unlike these models, novel non-parametric dynamic models have been developed using analytical average-value modeling approach in this work. In this modeling approach, depending upon the number of switches conducting during a switching cycle, the operating point of the rectifier is brought into one of three modes of operation of a six-pulse rectifier. The model for each mode is represented by a differential equation. During output current calculation for the rectifier the operating model is selected based on firing angle and overlap angle functions derived in this paper. They completely characterize the dynamic behavior of current flowing through the dc inductor for a wide range of operating conditions with the exception of harmonics and asymmetrical currents which are dominant for faults occurring at the terminals of the rectifier upstream of the smoothing inductor. The results from the average value model and few other simple models have been applied for Thevenin ac source and synchronous generator supplied rectifier models to determine the characteristics of short circuit current from the rectifier. / text

Content of this diploma thesis is project of the digital control design for a thyristor source with GSM communication. Designed for corrosion protection. The work contain design of the whole device from the initial proposals of the electro diagrams up to finished product. It describes the events that arise in corrosion, explains the principle of operating a thyristor as a power switch. It also describes the creation and structure of a simple menu using the STM32 microprocessor. It explains the principle of controlling a source. Next, it deals with controlled rectifiers using a thyristor.

The hardware validation of a novel average-value model (AVM) for the simulation of a synchronous-generator/controlled rectifier system is presented herein. The generator is characterized using genetic algorithm techniques to fit standstill frequency response (SSFR) measurements to q and d-axis equivalent circuits representing the generator in the rotor reference frame. The generator parameters form the basis of a detailed model of the system, from which algebraic functions defining the parametric AVM are derived. The average-value model is compared to the physical system for a variety of loading and operating conditions including step load change, change in delay angle, and external closed-loop control, validating the model accuracy for steady-state and transient operation.

O presente trabalho tem como principal objetivo construir um conversor CA/CC de baixo custo e elevado fator de potÃncia para o carregamento de baterias. A topologia proposta foi escolhida apÃs uma revisÃo das caracterÃsticas dos retificadores usuais para esse fim. Diferente dos outros, apresenta aspectos de robustez que o tornam apropriado para operar em localidades remotas. O retificador trifÃsico semicontroladoem alta frequÃncia (RTSCAF) à construÃdo com um nÃmero reduzido de chaves semicondutoras. O elevador de tensÃo à alimentado por uma turbina com umgerador sÃncrono a ÃmÃs permanentes (PMSG). Um circuito de controle em malha aberta efetua a comutaÃÃo das chaves para a operaÃÃo no modo de conduÃÃo descontÃnuo (DCM).Esse modo mantÃm as correntes em fase com as tensÃes, resultando em elevado fator de potÃncia e baixa distorÃÃo harmÃnica total (DHT), implicando em eficiente transferÃncia de potÃncia. Foi construÃdo um protÃtipo com potÃncia de saÃda de 250 W, para carregar um banco de baterias de 48 V. Os testes foram realizados com um aerogerador de baixa rotaÃÃo, atà 1 kW, acionado por um motor com variador de tensÃo, emulando as condiÃÃes do vento. Foram obtidos um fator de potÃncia de 0,98 e DHT na corrente de entrada de18%, resultados experimentais que validam a funcionalidade do conversor proposto. / The main objective of this work is to build a low cost CA/CC battery charging with high power factor to small energy wind power supply. The proposed topology has been chosen after a review of rectifiersâ characteristics used for this proposal. Unlike the others proposals, the topology was designed take in a count aspects that make it appropriated to operate in remote areas. A semi controlled three phase rectifier operating in high frequency was built with a reduced numbers of semiconductors. The system is powered by a synchronic generator turbine of permanent magnets A control unit runs in open loop with a control strategy of key switching operating in discontinuous conduction mode (DCM) that ensure high power factor and low harmonic distortion total, improving the power transfer efficiency. The prototype output power was 250 W, it was specified to charge a 48 V battery bank. Tests were conducted in low speed and wind power by 1 kW. A motor was drived as variable voltage charge to emulating wind conditions. Goods results were obtained like a power factor of 0.98 and the input current THD 18%, experimental results was carried out to validate the functionality of the proposed converter.

Orientador: Falcondes José Mendes de Seixas / Resumo: Os conversores multipulsos têm sido muito utilizados para a melhoria da qualidade de energia elétrica em sistemas de retificação trifásicos. O principal motivo para tal afirmação é a robustez apresentada por esses conversores, aliada às características intrínsecas da estrutura, que resulta no cancelamento natural de certas componentes de corrente na rede, devido ao defasamento angular provocado pela ação do transformador ou autotransformador utilizado. O que se propõe nesse trabalho é a substituição de cada ponte retificadora a diodos, presente no conversor de 12 pulsos, por uma topologia retificadora trifásica semicontrolada, baseada no conversor boost operando no modo de condução descontínuo (MCD), de modo que, seja possível reduzir de maneira significativa a DHTi (Distorção Harmônica Total de corrente), bem como, incorporar os volumosos transformadores de interfase (IPTs) aos indutores boost de alta frequência, resultando na redução de peso e volume. Foram confeccionadas duas versões do conversor de 12 pulsos com retificadores semicontrolados, uma utilizando transformador isolador e a outra um autotransformador. O que se verificou para ambas as configurações é que a estrutura apresenta um reduzido conteúdo harmônico de corrente se comparado ao conversor tradicional e que, ao se operar no modo de condução descontínuo, faz-se possível o emprego de uma lógica de controle simples, possibilitando assim empregar somente uma malha de tensão, e reduzir significativamente a DHTi do... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Multipulse converters have been widely employed for electrical power quality improvement in three-phase rectifiers systems. The main reason for this statement is the robustness shown by these structures, allied to their natural characteristics, resulting in harmonic canceling at the mains, due to the phase displacement provided by the transformer/autotransformer. In this work, it is proposed the replacement of each rectifier bridge, present in the 12-pulse converter, by a three-phase half-controlled rectifier topology, based on DCM (Discontinuous Conduction Mode) boost converter, thus making it possible to significative reduce the THDi (Total Harmonic Distortion) of the current injected on the mains by the structure. It also incorporates the voluminous IPT's (Interphase Transformer) in the boost high-frequency inductor, resulting in a reduction of weight and size. Two versions of the 12-pulse converter with semicontrolled rectifiers were made, one using an isolating transformer and other using an autotransformer. It was verified that both configurations present a reduced THDi when compared to the traditional converter. So, by electing DCM, it is possible to employ a simpler control logic, employing only one voltage loop and significantly reducing the THDi. / Doutor