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Correção do fator de potência em fontes chaveadas com microcontrolador

Lange, André de Bastiani
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
POR
Relevância na Pesquisa
66%
O presente trabalho aborda a análise, o projeto, a implementação e os ensaios de um retificador com correção ativa do fator de potência, o qual permite alimentar cargas CC a partir de uma fonte senoidal, injetando baixo conteúdo harmônico na corrente de alimentação e operando com fator de potência unitário. Serão desenvolvidos os circuitos de potência e o software para o controle e a modulação do conversor boost utilizado para o propósito citado. Os resultados obtidos demonstram que as abordagens matemáticas que caracterizam o funcionamento do boost em condução descontínua são suficientemente precisas para que o controle em malha aberta da corrente de alimentação funcione adequadamente, resultando em um fator de potência muito próximo da unidade.; This research aims to present the analysis, design, implementation and testing of a rectifier with active power factor correction, which powers DC loads from sinusoidal sources while injecting low harmonic content into the supply current and operating with unity power factor. It shows the development of the power circuits and the software for control and modulation of the boost converter used for the previously described purpose. The results showed that the mathematical approaches which characterize the boost operation in discontinuous conduction are sufficiently precise to allow the open-loop control strategy of the supply current to work as expected...

Conversor CC/CC aplicado à correção do fator de potência

Spomberg, Thiago Kotarba
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
POR
Relevância na Pesquisa
76.1%
O baixo fator de potência significa que grande parte da energia utilizada está sendo desperdiçada. Alguns equipamentos introduzem harmônicas de corrente na rede elétrica que acabam por deteriorar a qualidade do serviço e o funcionamento adequado de outros aparelhos. O presente trabalho apresenta uma proposta de correção do fator de potência empregando um conversor do tipo boost com a finalidade de substituir fontes retificadoras convencionais. Baseado no circuito integrado UC3854, facilmente encontrado no mercado local, o protótipo prioriza um alto fator de potência, no sentido mais amplo da definição, assim como uma regulação da tensão de saída para a faixa de alimentação especificada. São apresentadas a descrição do circuito de controle e resultados de ensaios práticos que validam o estudo.; A poor power factor means that a considerable portion of energy used is being wasted. Some equipments inject harmonic distortion into the power supply that damage the quality of the service and proper operation of other devices. The aim of this work is to present a suggestion for Power Factor Correction (also known as PFC) by using a Boost regulator in order to replace conventional sources. Based on the Unitrode UC3854...

Sistema de tração elétrica flexível baseado em veículos trólebus para alimentação com redes CC e ou CA

Melo, Guilherme A.; Oliveira, Rodrigo N.; Brito, Moacyr A. G. de; Gonçalves, Flávio A. S.; Canesin, Carlos A.
Fonte: Sociedade Brasileira de Automática Publicador: Sociedade Brasileira de Automática
Tipo: Artigo de Revista Científica Formato: 608-620
POR
Relevância na Pesquisa
75.96%
Este artigo apresenta os principais resultados e o detalhamento da metodologia e equações de controle de um retificador monofásico pré-regulador de 150kW para sistema trólebus. A estrutura proposta possibilita a Correção ativa do Fator de Potência (CFP) com baixos níveis de Distorção Harmônica Total (DHT) na corrente, em conformidade com a norma internacional IEC 61000-3-4. Fruto de um projeto de Pesquisa, Desenvolvimento e Inovação (P) junto à empresa AES Eletropaulo Metropolitana de São Paulo, em parceria com a empresa de transporte Himalaia S.A., o projeto possui como principais objetivos estimular o interesse para a expansão das linhas de trólebus a partir de uma plataforma de alimentação de menor custo de instalação e manutenção, sem a necessidade de subestações retificadoras, e, com vistas a promover a melhoria da qualidade de vida nos grandes centros urbanos. Nessa nova modalidade proposta para o sistema de alimentação, o trólebus pode ser alimentado tanto pelas redes convencionais em corrente contínua (CC) quanto pelas redes de distribuição em corrente alternada (CA), mantendo-se a disposição a dois fios dos sistemas CC, sendo as mudanças de rede de alimentação (CC ou CA) monitoradas e controladas digitalmente. Todo o sistema de gerenciamento e controle do conversor é realizado digitalmente por FPGA XC3S200. Na evolução do sistema proposto...

Power Factor Correction Boost Converter Based on the Three-State Switching Cell

Robles Balestero, Juan Paulo; Tofoli, Fernando Lessa; Fernandes, Rodolfo Castanho; Torrico-Bascope, Grover Victor; Seixas, Falcondes José Mendes
Fonte: Institute of Electrical and Electronics Engineers (IEEE) Publicador: Institute of Electrical and Electronics Engineers (IEEE)
Tipo: Artigo de Revista Científica Formato: 1565-1577
ENG
Relevância na Pesquisa
106.01%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); The need for solid-state ac-dc converters to improve power quality in terms of power factor correction, reduced total harmonic distortion at input ac mains, and precisely regulated dc output has motivated the investigation of several topologies based on classical converters such as buck, boost, and buck-boost converters. Boost converters operating in continuous-conduction mode have become particularly popular because reduced electromagnetic interference levels result from their utilization. Within this context, this paper introduces a bridgeless boost converter based on a three-state switching cell (3SSC), 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 autotrans-formers and high power levels. A literature review of boost converters based on the 3SSC is initially presented so that key aspects are identified. The theoretical analysis of the proposed converter is then developed...

A true programmable HPF hybrid three-phase rectifier

Soares, Jurandir de O.; Canesin, Carlos A.; Freitas, Luiz C. de
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 3843-3849
ENG
Relevância na Pesquisa
66.08%
In this paper is proposed and analyzed a digital hysteresis modulation using a FPGA (Field Programmable Gate Array) device and VHDL (Hardware Description Language), applied at a hybrid three-phase rectifier with almost unitary input power factor, composed by parallel SEPIC controlled single-phase rectifiers connected to each leg of a standard 6-pulses uncontrolled diode rectifier. The digital control allows a programmable THD (Total Harmonic Distortion) at the input currents, and it makes possible that the power rating of the switching-mode converters, connected in parallel, can be a small fraction of the total average output power, in order to obtain a compact converter, reduced input current THD and almost unitary input power factor. The proposed digital control, using a FPGA device and VHDL, offers an important flexibility for the associated control technique, in order to obtain a programmable PFC (Power Factor Correction) hybrid three-phase rectifier, in agreement with the international standards (IEC, and IEEE), which impose limits for the THD of the AC (Alternate Current) line input currents. Finally, the proposed control strategy is verified through experimental results from an implemented prototype. ©2008 IEEE.

Bridgeless interleaved boost PFC converter with variable duty cycle control

E Silva, Luciano S.C.; De Seixas, Falcondes J.M.; De Brito, Moacyr A.G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 397-402
ENG
Relevância na Pesquisa
76.15%
This paper proposes a bridgeless boost interleaved PFC (power factor correction) converter with variable duty cycle control. The application of bridgeless technique causes reduction of conduction losses, while the interleaving technique of converters cells allows division of efforts in semiconductor devices and reduction of weight and volume of the input EMI filter. The use of variable duty cycle control has the functions of regulating the output voltage and eliminating the low order harmonic components that appears in the input current of the common interleaved power factor converters working in Discontinuous Conduction Mode (DCM). The simulation results of the proposed converter presented high power factor and a good transient response in relation to the output voltage regulation in presence of high load variations and supply voltage variations. © 2011 IEEE.

Experimental evaluation of the bridgeless interleaved boost PFC converter

E Silva, Luciano S. C.; De Seixas, Falcondes J.M.; Oliveira, Priscila Da S.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
76.12%
This paper presents theoretical evaluation and experimental results to the proposed bridgeless interleaved boost PFC (power factor correction) converter. The application of bridgeless technique causes reduction of conduction losses, while the interleaving technique of the converter cells allows division of the current stress in semiconductor devices and reduction of weight and volume of the input EMI filter. In each cell of the converter, the inductor current operates in discontinuous conduction mode (DCM), which eliminates turn-on switching losses and the effects of reverse recovery in semiconductors, increasing the efficiency of the converter. The experimental results show the power factor of 0.96 for employed voltage ratio and an efficiency of 95.2 % for nominal load conditions. © 2012 IEEE.

Técnica para correção do fator de potência e aumento da suportabilidade dos circuitos retificadores a afundamentos temporários de tensão; Technique for power factor correction and ride-through capability Improvement of rectifier circuits to voltage sags

Silva, Daniel Divino Rodrigues da
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
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Este trabalho apresenta uma nova proposta de controle para conversor boost operando como retificador de alto fator de potência, a qual permite priorizar o requisito de alto fator de potência, sob condição normal da rede, ou priorizar a regulação da tensão de saída diante de afundamentos de tensão. O controle implementado consiste na modificação das malhas de realimentação do circuito 3854. O sistema de monitoramento contém o microcontrolador LPC2138, que comanda a alteração das malhas do 3854 em função das condições de operação da rede elétrica. A proposta supracitada objetiva a concepção de um conversor boost PFC – “Power Factor Correction” com maior suportabilidade perante os afundamentos de tensão de elevada ordem. São apresentados resultados experimentais de um protótipo submetido a estes distúrbios, os quais contemplam a comparação da performance do sistema proposto com a de um conversor PFC convencional. _________________________________________________________________________________ ABSTRACT; This work presents a new approach for PFC boost converter controller, which sets the priority of the controller to high power factor, under normal utility condition, or output voltage regulation, under sag condition. The new controller is based on modification of chip 3854 feedback loop. The monitoring system has a LPC2138 microcontroller that modifies the 3854 feedback loop depending of the energy network condition. This proposal conceives a ride-through capability improvement of PFC boost converters to hard voltage sags. Experimental results under normal and sag conditions are shown. Through these results it is possible to compare the performance between the proposed system and the ordinary PFC converter.; Dissertação (mestrado)-Universidade Federal de Uberlândia...

Comparison of AC mains synchronization methods when using precalculated duty cycles in Power Factor Correction

Sánchez, Alberto; Castro, Ángel de; López-Colino, Fernando; Garrido, Javier
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
66.11%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. A. Sánchez, Á. de Castro, F. J. López Colino, and J. Garrido, "Comparison of AC mains synchronization methods when using precalculated duty cycles in Power Factor Correction", 2014 IEEE 15th Workshop on in Control and Modeling for Power Electronics (COMPEL), 2014, Santander (Spain), pp. 1 - 4; Classic PFC (Power Factor Correction) converters usually have three sensors: input voltage, input current and output voltage. Instead of using these three measures to calculate the duty cycle, precalculated duty cycles can be stored in a memory. With this memory, the system only has to synchronize with the ac mains and apply the duty cycles, at least for nominal conditions. This paper shows several methods to accomplish this synchronization, using an ADC or a voltage comparator. Results show that PFC can be achieved using simple synchronization methods and precalculated duty cycles.

Single ADC single loop power factor correction using pre-calculated duty cycles

Sánchez, Alberto; Castro, Ángel de; Garrido, Javier
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
65.99%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. A. Sánchez, A. de Castro, and J. Garrido, "Single ADC single loop power factor correction using pre-calculated duty cycles", in 2013 15th European Conference on Power Electronics and Applications (EPE), Lille (France), 2013, pp. 1-6; PFC controllers usually need three sensors. A digital implementation with pre-calculated duty cycles can reduce the number of sensors. The disadvantage of using pre-calculated duty cycles is that power factor is very sensitive to any non-idealities, so some kind of regulation is necessary. A single ADC and single loop technique is proposed and it obtains a high power factor under non-nominal conditions.

High-resolution error compensation in continuous conduction mode power factor correction stage without current sensor

López-Martín, Víctor M.; Azcondo, Francisco Javier; Castro, Ángel de
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: conferenceObject; bookPart
ENG
Relevância na Pesquisa
76.17%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. V. M. López-Martín, F. J. Azcondo, and Á. de Castro, "High-resolution error compensation in continuous conduction mode power factor correction stage without current sensor", in 2012 15th International Power Electronics and Motion Control Conference (EPE/PEMC), Novi Sad (Serbia), 2012.; Continuous conduction mode power factor correction (PFC) without input current measurement is a step forward with respect to previously proposed PFC digital controllers. Inductance volt-second (vsL) measurement in each switching period enables the estimation of input current, but an accurate compensation of the small errors in the measured vsL is required. Otherwise, they are accumulated over a half-cycle line, leading to an appreciable current distortion. A vsL estimation is proposed, measuring the input (vin) and the the output voltage (vo). Discontinuous conduction mode (DCM) occurs near input line zero crossings...

Autotuning digital controller for current sensorless power factor corrector stage in continuous conduction mode

López-Martín, Víctor M.; Azcondo, Francisco Javier; Díaz, Francisco Javier; Castro, Ángel de
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: conferenceObject; bookPart
ENG
Relevância na Pesquisa
66.17%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. V. M. López, F. J. Azcondo, F. J. Díaz, and Á. de Castro, "Autotuning digital controller for current sensorless power factor corrector stage in continuous conduction mode", 2010 IEEE 12th Workshop on Control and Modeling for Power Electronics (COMPEL), Boulder (CO), 2010, pp. 1-8; A circuit that compensates the volt-seconds error across the inductor in current sensorless digital control for continuous conduction mode power factor correction (PFC) stage is presented. Low cost ad-hoc sigma-delta analog to digital converters (ΣΔ ADCs) are used to sample the PFC input and output voltage. Instead of being measured, the input current is estimated in a digital circuit to be used in the current loop. A nonlinear carrier control is implemented in the digital controller in order to obtain the power factor correction. Drive signal delays cause differences between the digital current and the real current...

Universal digital controller for boost CCM power factor correction stages based on current rebuilding concept

López-Martín, Víctor M.; Azcondo, Francisco Javier; Castro, Ángel de; Zane, Regan A.
Fonte: IEEE Publicador: IEEE
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
76.22%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. V. M. López, F. J. Azcondo, A. de Castro, R. Zane, "Universal Digital Controller for Boost CCM Power Factor Correction Stages Based on Current Rebuilding Concept", IEEE Transactions on Power Electronics, vol. 29, no. 7, pp. 3818 - 3829, July 2014.; Continuous conduction mode power factor correction (PFC) without input current measurement is a step forward with respect to previously proposed PFC digital controllers. Inductor volt-second (vsL) measurement in each switching period enables digital estimation of the input current; however, an accurate compensation of the small errors in the measured vsL is required for the estimation to match the actual current. Otherwise, they are accumulated every switching period over the half-line cycle, leading to an appreciable current distortion. A vsL estimation method is proposed, measuring the input (vg) and output voltage (vo). Discontinuous conduction mode (DCM) occurs near input line zero crossings and is detected by measuring the drain-to-source MOSFET voltage vds. Parasitic elements cause a small difference between the estimated voltage across the inductor based on input and output voltage measurements and the actual one...

Corrección de factor de potencia basada en la estimación digital de la corriente de línea : aplicación en el convertidor Boost en modo de conducción continua; Digital power factor correction based on line-current estimation : CCM Boost converter application : Tesis doctoral

López Martín, Víctor Manuel
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
106.28%
RESUMEN: En esta tesis se presenta un controlador digital universal de corrección de factor de potencia basado en la estimación digital de la corriente de entrada. En dicha estimación se tiene en cuenta todas las fuentes de error en la estimación de la corriente debido a la implementación real del estimador, que introducen una diferencia entre la tensión medida en la inductancia y la real (tanto en términosde voltios como en términos de tiempo). Para compensar esta desviación. Una compensación feedforward para compensar errores con la variable tiempo, y un lazo de realimentación digital feedback que cancela la diferencia de tiempos el modo de conducción discontinua (MCD) de la corriente real de entrada (TgDCM) y de la corriente digital reconstruida (TrebDCM). Se presenta además una modificación en el control no-lineal de corrección de factor de potencia (NLC), para asegurar una corriente sinusoidal ante tensiones de red distorsionadas. Los resultados experimentales, obtenidos con un Boost PFC bajo diferentes condiciones muestran el comportamiento del control propuesto.; ABSTRACT: Continuous conduction mode (CCM) power factor correction (PFC) without input current measurement is a step forward with respect to previously proposed PFC digital controllers. Inductor volt-second (vsL) measurement in each switching period enables the digital estimation of the input current...

Pre-calculated duty cycle control implemented in FPGA for power factor correction

García Ávila Fernández, Alejandro; Castro, Ángel de; Muñoz García, Óscar; Azcondo, Francisco Javier
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: conferenceObject; bookPart
ENG
Relevância na Pesquisa
76.13%
Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. A. García Ávila Fernández, Á de Castro, Ó. Muñoz García, and F. J. Azcondo, "Pre-calculated duty cycle control implemented in FPGA for power factor correction", 35th Annual Conference of IEEE Industrial Electronics, 2009. IECON '09, Porto (Portugal), 2009, pp. 2955 - 2960; A power factor correction (PFC) technique based on pre-calculated duty cycle values is presented in this paper. In this method the duty ratios for half a line period are calculated in advance and stored in a memory. By synchronizing the memory with the line, near unity power factors can be achieved in a specific operating point. The main advantage of this technique is that neither current measurement nor current loop are needed. To obtain stable output voltages a voltage loop is included. A boost converter prototype controlled by an FPGA evaluation board has been implemented in order to verify the functionality of the proposed method. Both the simulation and experimental results show that near unity power factor can be achieved with this PFC strategy.

Analysis and Design of High Power Factor LED Drivers without Electrolytic Capacitor

Hao, Ting
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
86.06%
With superior longevity, approximately 5 times that of compact fluorescents (CFLs), and high efficacy, around 1.5 times that of CFLs, LEDs are now attracting vast attention from both academic and industrial sectors. Unfortunately, current power supply drivers for LEDs have the following drawbacks: (1) for a two-stage configuration, the power factor correction (PFC) circuit can help LEDs achieve good operating performance but contain too many components and are large in size, have low efficiency and relatively high cost; (2) a single-stage configuration can perform well in PFC and efficiency, however reliability issues occur due to the use of the electrolytic capacitor. In this thesis, the theoretical analysis and implementation of two high power factor, soft-switched, electrolytic-capacitor-less LED drivers are presented. The two drivers solve the aforementioned issues while minimizing its size and cost. The detailed theoretical analysis illustrates the advantages of the presented circuits and provides insight into their design and operation. The simulated and experimental implementations verified the performance of both circuits, which achieve a high power factor, indicating that the drivers have good operating performance. Elimination of the electrolytic capacitors improves the LED drivers’ reliability. In addition...

Power Converters for Electric Vehicles

Pahlevaninezhad, Majid
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
65.96%
This thesis presents topologies and control methods to improve the efficiency and dynamic response of Electric Vehicle (EV) power converters. There are three main converters in an EV power conditioning system: a plug-in AC/DC converter, a low-voltage DC/DC converter, and a three-phase inverter. The focus of this thesis is to improve the plug-in AC/DC converter and the low-voltage DC/DC converter. A new topology is proposed to improve the efficiency and increase the reliability of the plug-in AC/DC converter. The plug-in AC/DC converter consists of a Power Factor Correction (PFC) stage, which is followed by a high voltage DC/DC converter for galvanic isolation. The proposed approach includes a simple and effective auxiliary circuit for the PFC stage, which guarantees soft-switching for the power switches. Next, a current-driven full-bridge topology is proposed for the high-voltage DC/DC conversion stage, which guarantees soft-switching and eliminates voltage spikes across the output diodes. Also, two control approaches are proposed in order to improve the dynamic response of the AC/DC converter. The first controller is based on nonlinear differential flatness theory, which can be used to improve the transient response of the AC/DC converter. The second controller is based on an optimized stabilizing control-Lyapunov function...

A Dimmable High Power Factor Electronic Ballast for Compact Fluorescent Lamps

Lam, John
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
75.96%
Incandescent lamps are now being gradually replaced by Compact Fluorescent Lamps (CFLs) as CFLs consume less power to produce the same light output and its lifetime is much longer than that of an incandescent lamp. However, current CFLs have the following drawbacks: (1) the line current drawn from the CFL produce a large amount of unwanted harmonics that results in very poor input power factor; (2) the dimming performance of a CFL with conventional incandescent lamp dimmers is very poor. The performance of the CFL depends on the design of the electronic ballast circuit that is located at the base of each CFL. For a CFL electronic ballast to be practical, its size and cost is of utmost importance. Thus, the main challenge in the design of practical dimmable CFL ballasts is to solve the aforementioned CFL performance issues while minimizing its size and cost. In the first part of this dissertation, two novel high power factor single-stage electronic ballast topologies are proposed to solve the poor power factor issue of the CFLs that are currently on the market. Both proposed circuits have the following advantages: (1) only one switch is required in the power circuit; (2) the switch has both lower current and voltage stress than other conventional circuits; (3) the built-in power factor correction (PFC) circuit allows incandescent phase-cut dimmer to be used for dimming the CFL; (4) the circuit design is simple and it requires less system space compared to other conventional high PF electronic ballast topologies. The second part of this dissertation proposes a new control circuit that enables the lamp to maintain high power factor throughout the majority of the dimming range. In the proposed control scheme...

Analysis of power factor correction converters

Yeh, Thomas
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
86.37%
Power Converter with capacitive input filter is a non-linear load to the Utility AC power lines. There are widely used as Switch-Mode Power Supplies in office equipment applications ranging from Personal Computers to Office Printers and Copiers. The distorted input current waveform extracted by the capacitive input filter of the power converters produces unwanted harmonics which propagates to other line powered equipments. The harmonic pollutes the AC lines and interferes with the operations of sensitive line powered equipments. The distorted current waveform also leads to inefficient utilization of the available power from the AC outlet. This is because the AC line power is transferred to the load only when each frequency component of the line voltage is an in-phase, scaler related quantity with respect to the same frequency component of the extracted current. The problems of poor power factor and harmonic distortion are compounded by the proliferation of Switch-Mode power supplies and the situation is rapidly becoming intolerable. The problem of poor quality input current waveform can be described by two quantitative measurements: Power Factor (pf) and Total Harmonic Distortion (thd). Two general approaches are available to remedy the problem. One approach is to install passive filter networks between the Utility AC lines and the capacitive input filter. The second approach is to design active power processors as dedicated Power Factor Correction (pfc) Converters and installed as the front end to the capacitive input filter to shape the distorted current waveform into waveforms which will yield higher power factor. This Thesis first introduce the general concept of PF and harmonic distortion in Chapter 1. Chapter 2 derive the mathematical description of pf based on the concept of real power (pR) and apparent power {pA). Both sinusoidal and nonsinusoidal cases are studied. For comparison and completeness...

A review of electrical energy management techniques: Supply and consumer side (industries)

Mohamed,Afua; Khan,Mohamed Tariq
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
76.03%
A review of electrical energy management techniques on the supply side and demand side is presented. The paper suggests that direct load control, interruptible load control, and time of use (TOU) are the main load management techniques used on the supply side (SS). The supply side authorities normally design these techniques and implement them on demand side consumers. Load management (LM) initiated on the demand side leads to valley filling and peak clipping. Power factor correction (PFC) techniques have also been analysed and presented. It has been observed that many power utilities, especially in developing countries, have neither developed nor implemented DSM for their electrical energy management. This paper proposes that the existing PFC techniques should be re-evaluated especially when loads are nonlinear. It also recommends automatic demand control methods to be used on the demand side in order to acquire optimal energy consumption. This would lead to improved reliability of the supply side and thereby reducing environmental degradation.