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.

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