The research presents two novel high power factor ac-to-dc resonant converters with symmetrical topologies and zero-voltage-switching (ZVS) operation. The derived circuits are obtained from the integration of a dual-switch boost-type or buck-boost-type power factor corrector (PFC) into a half-bridge resonant converter. With symmetrical topology, the circuit is simple and the voltage and current stresses on the two active power switches are identical to each other. The PFC is operated at discontinuous conduction mode (DCM) to achieve unity power factor. The resonant energy tank of half-bridge resonant converter is designed to be inductive to retain ZVS operation. The design equations are derived based on fundamental approximation. Prototypes of the two proposed converters designed for 100 W and 50 W, respectively, were built and tested to verify the computer simulations and analytical predictions. Satisfactory results are obtained experimentally.

The critical conduction mode (CRM) power factor correction converters (PFC) are widely used in industry for low power offline switching mode power supplies. For the CRM PFC, the main advantage is to reduce turn-on loss of the main switch. However, the large inductor current ripple in CRM PFC creates huge DM EMI noise, which requires a big EMI filter. The switching frequency of the CRM PFC is variable in half line cycle which makes the EMI characteristics of the CRM PFC are not clear and have not been carefully investigated. The worst case of the EMI noise, which is the baseline to design the EMI filter, is difficult to be identified. In this paper, an approximate mathematical EMI noise model based on the investigation of the principle of the quasi-peak detection is proposed to predict the DM EMI noise of the CRM PFC. The developed prediction method is verified by measurement results and the predicted DM EMI noise is good to evaluate the EMI performance. Based on the noise prediction, the worst case analysis of the DM EMI noise in the CRM PFC is applied and the worst case can be found at some line and load condition, which will be a great help to the EMI filter design and meanwhile leave an opportunity for the optimization of the whole converter design. What is more, the worst case analysis can be extended to 2-channel interleaved CRM PFC and some interesting characteristics can be observed. For example, the great EMI performance improvement through ripple current cancellation in traditional constant frequency PFC by using interleaving techniques will not directly apply to the CRM PFC due to its variable switching frequency. More research needs to be done to abstract some design criteria for the boost inductor and EMI filter in the interleaved CRM PFC. / Master of Science

La proliferación en los últimos años de equipos electrónicos conectados a redes de distribución eléctrica, ha provocado la aparición de standards internacionales, como por ejemplo la norma EN 68000-3-2, que regulan la distorsión armónica de baja frecuencia que dichos equipos pueden introducir en la red. En este contexto, los rectificadores con alto factor de potencia constituyen una de las soluciones más adecuadas para reducir la distorsión armónica de la corriente consumida de la red eléctrica. En su versión monofásica y cuando no se requiere devolver energía a la red, los rectificadores con alto factor de potencia suelen implementarse mediante la asociación en cascada de un rectificador pasivo (diodos) y un convertidor dc-dc de tipo boost. Un lazo de regulación de corriente se encarga de mantener la distorsión de la corriente de entrada próxima a cero, recibiendo una señal de consigna de un lazo de regulación de la tensión de salida. Este último lazo se encarga de mantener la tensión de salida cercana a un cierto valor de referencia. El problema más documentado en la literatura al respecto es la pobre respuesta dinámica del lazo de regulación de tensión, debido a que dicho lazo debe ser extremadamente lento para no producir distorsión en la corriente de entrada. En esta tesis se propone la aplicación de las técnicas de control Robust Model Following (RMF) y Load Injection Current (LI2) al diseño del lazo de regulación de la tensión de salida. Dichas técnicas permiten reducir considerablemente la impedancia de salida del convertidor en lazo cerrado, sin que se requiera aumentar la velocidad de respuesta del lazo de tensión. En consecuencia, mejoran de forma notable la respuesta dinámica del convertidor sin distorsionar la corriente de entrada. Una ventaja adicional de las técnicas propuestas es su bajo coste de implementación, lo que las convierte en una alternativa muy interesante para ser implementadas en equipos industriales. / Benavent García, JM. (2010). Técnicas de control robusto basado en modelo de referencia e inyección de la corriente de carga aplicadas a rectificadores monofásicos con corrección activa del factor de potencia [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8684 / Palancia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master Thesis presents the study and proposes a digital control system applied to the PFC boost converter operating in mixed conduction mode. The motivation to this subject, a bibliographic review of the existing current control techniques and the objectives of this work are presented in the first chapter. The control system is composed of a current loop, which has the objectives to provide low harmonic content to the input current and high power factor to the converter, and a voltage loop, which has the goal to regulate the output voltage of the converter. Initially, the study of the conduction modes of the PFC boost converter, highlighting their operation conditions, and details of the mixed conduction mode operation are showed. Next, two predictive digital current controllers with feedforward action are approached in details, including the equations deduction, block diagram, operation process, design, simulation results and parametric variation analysis. A comparative analysis between both controllers is also accomplished. The proportional-integral voltage controller is presented following, comprising its structure, design and simulation results. After, issues related to the practical implementation of the converter and control system, as the converter design and the control device programming, are shown. Finally, the experimental results obtained through the implementation of the proposed system, including the waveforms acquired using a prototype constructed in laboratory and the quality indexes as the power factor and the total harmonic distortion, are presented with the purpose to validate and prove the content of this work. / Esta Dissertação de Mestrado apresenta o estudo e propõe um sistema de controle digital para o conversor boost PFC operando no modo de condução mista. A motivação para este assunto, uma revisão bibliográfica das técnicas de controle de corrente existentes e os objetivos do trabalho são apresentados no capítulo introdutório. O sistema de controle é composto de uma malha de corrente, que tem por objetivo proporcionar baixo conteúdo harmônico para a corrente de entrada e alto fator de potência para o conversor, e uma malha de tensão, que tem por objetivo regular a tensão de saída do conversor. Inicialmente, o estudo dos modos de condução do conversor boost PFC, destacando as suas condições de operação, e detalhes da operação no modo de condução mista são mostrados. Em seguida, dois controladores digitais preditivos de corrente com ação feedforward são abordados em detalhes, incluindo o equacionamento, diagrama de blocos, funcionamento, projeto, resultados de simulação e análise da variação paramétrica. Uma análise comparativa entre ambos também é realizada. O controlador proporcional-integral de tensão é abordado na seqüência, compreendendo sua estrutura, projeto e resultados de simulação. Posteriormente, questões relativas à implementação prática do conversor e do sistema de controle, como o projeto do conversor e a programação do dispositivo de controle, são mostradas. Por fim, os resultados experimentais obtidos com a implementação do sistema proposto, incluindo as formas de onda adquiridas em um protótipo construído em laboratório e os índices de qualidade como o fator de potência e a distorção harmônica total, são apresentados com o intuito de validar e comprovar o conteúdo deste trabalho.

The thesis is focused on design the switching power supply according to Push-pull topology rules. The work describes basic theoretic principles of Push-pull topology with design of circuit and circuit elements.