A Very Simple Control Strategy for Power Factor Correctors Driving High-Brightness LEDs

This paper presents a new control strategy for power factor correctors (PFCs) that are used to drive high-brightness LEDs. This control strategy is extremely simple and is based on the use of a conventional peak-current-mode controller with a suitable selection of the compensation ramp waveform. Neither an analog multiplier nor an input voltage sensor is needed to achieve quasi-sinusoidal line waveforms at nominal conditions and full load. If the converter belongs to the flyback family (flyback, buck–boost, SEPIC, Cuk and Zeta), the line waveform appears notably distorted if the compensation function is a linear ramp, but becomes almost sinusoidal if the linear ramp is substituted by a properly chosen exponential function. The line waveform is slightly distorted when the load varies or when the converter works under either overvoltage or undervoltage conditions. However, the waveform maintains a very high power factor (PF) even under these conditions. Moreover, the line current is cycle-by-cycle-controlled due to the peak-current-mode control, and hence, the input-current feedback loop is extremely fast, thereby allowing this type of control to be used with high-frequency lines (above 400 Hz).      

效率、功率因数及其关系的讨论

效率和功率因数是电气与电子工程中的两个重要参数.它们既是两个不同的概念,又有密切的联系.但在目前的电路分析及模拟电子技术的部分教材中,关于效率、功率因数及其关系问题仍然存在一些错误概念,或者对这些重要的问题言之甚少.本文针对上述问题作了详细地讨论.并通过一个例子分析了效率及功率因数之间的关系,纠正了对这些问题的模糊认识,使这些概念更加明确.笔者认为文中的分析和讨论对电类各专业的学生掌握这些基本问题是有益的.     

Two-Stage Uninterruptible Power Supply With High Power Factor

An uninterruptible power supply (UPS) with high power factor and two conversion stages is suggested. The double-conversion configuration has three stages, but normally, only two stages are operating at the same time. The first stage of the proposed scheme integrates the power-factor-correction stage and the battery charger of the double-conversion configuration, obtaining a two-stage UPS. The second stage is based on the theory of inverter with boosting capabilities. The battery set has not only been completely isolated, but it has also been charged with a small change at the controller set point; these particular characteristics facilitate the system maintenance and simplify its operation. Additionally, the battery-set voltage is low, reducing the weight and size. The converter operation, analysis, design, and experimental results are shown. The proposed UPS approach is practical in low-power applications ($leq 500$ W).      

高功率因素整流器技术综述

由三菱电机开发研制的MELVEC矢量控制变频调速系统的装置中，采用了具有PWM高功率因数整流的控制技术，并且使用了IGBT、GTO、IGCT等功率器件。提高了功率因数，已被广泛地应用在钢铁（冶金）行业中。本文简要说明其电路构成的原理，重点介绍和分析了高功率因数的控制技术、控制系统的设计理念，并简述了装置中高次谐波的问题。     

Power Utilization Factor (PUF)

It is shown that, in case of feeding loads with high levels of harmonic distortion, the RMS values of voltage and current no longer provide a reliable representation of the load, either in terms of its actual power efficiency or its tendency to introduce distortion. To cope with this sort of scenario, the use of a Power Utilization Factor (PUF), in addition to the usual Power Factor and Cos Phi, is suggested on analytical and experimental grounds. The use of the PUF enables a more reliable analysis of high distortion loads, as it better describes the relationship between the load and the power supply. Practical case studies are presented for a variety of loads, including the so called low consumption lamps, typical domestic loads (sorted as low consumption lamps, incandescent lamps, and common appliances) showing also the effect of these type of loads on step-down transformer. It is shown that the use of the PUF allows to keep track and quantify the relationship between distortion-producing loads and the ensuing distorted regulation of the electrical system.     

有源高功率因数电子镇流器

为了提高电子整流器的功率因数,讨论了高性能电子镇流器系统必须具备的电路结构和功率因数校正电路(PFC)的基本原理。介绍了一种以L6561为功率因数校正控制器的有源高功率因数电子镇流器,说明该镇流器的电路组成及L6561的主要特点,并给出详细的电路原理图及主要元器件的选型。     

通信机房无功功率补偿及功率因数改善

目前通信机房低压配电系统无功补偿普遍采用电容柜自动投切系统实现。近年来,这种无功补偿方案暴露出诸多弊端,也酿成不少事故。文中在对一起电容补偿柜烧毁事故进行技术分析的基础上,总结了利用电容器进行无功补偿的不足之处,分析了SVG（静态无功发生器）的基本原理及技术优势,提出了通信机房供电系统采用SVG作为无功补偿的新方案。     

开关电源功率因数的计算方法

介绍了大功率开关电源功率因数的概述及计算方法，给出了具体计算公式，在此基础上分析了一个具体实例。     

Power Quality und technisches Risikomanagement

Ohne Zusammenfassung Kurzfassung eines Vortrags, gehalten anl?sslich der 39. Fachtagung der ?sterreichischen Gesellschaft für Energietechnik im ?VE, die am 18. und 19. Oktober 2001 in Salzburg stattfindet.     

数字化功率因数补偿器的设计

数字化功率因数补偿器与一般的无功功率补偿装置不同．它由一片可擦除只读存储器芯片ＥＰＲＯＭ２７６４及组合逻辑电路等组成，可及时读出当时的功率因数和需补偿的电容数据，从而完成数字显示和补偿电容的切换控制．该方法成本低，控制精度高，抗干扰性能好．文章介绍了具体电路的设计、显示与切换的分时执行方式以及数据编制与电容的选择等．     

功率因数修正的模块化方法

大多数现代电子设备使用了开关式电源,它们会产生不希望出现的电流谐波.这些谐波对供电品质和与该电源系统连接的其它设备造成了不良影响.为了努力减小对电源系统的干扰,人们正越来越多地在电源中采用功率因数修正技术.通过采用一种能吸纳正弦波电流的电路结构,人们可以将谐波减至最低,并大大降低对系统的干扰.由于实际应用日益需要这一特征,所以如何找出功率因数修正的恰当方法就成为电源设计者要面对的一项挑战.……     

一种提高功率因数的GQS滤波电路

本文介绍了一种在直流电源中运用的带滤波电感的ＧＱＳ滤波电路,此电路在传统滤波电路的基础上,加用滤波电感,可大大降低对电网的谐波污染,提高电源的功率因数。     

一种新型高功率因数直流电源

文章提出了一种新型的高功率因数直流电源,并对电路的主要工作原理进行了分析,介绍了电路的两种工作模态,并且作了详细的比较;通过理论演算和对电路仿真,证实了该电路具有功率因数高的特点。与目前常用的boost功率因数校正电路比较,该电路改善了开关管的电压应力,使开关管不易损坏,同时还具有结构简单,效率高,性能稳定等优点。     

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

This paper presents a new single-stage power factor correction ac/dc converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant dc/dc converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the dc-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant dc-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90–265 Vrms).      

One-Cycle-Controlled Bidirectional AC-to-DC Converter With Constant Power Factor

Grid-connected unity-power-factor converters based on one-cycle control (OCC) do not require the service of phase-locked loop or any other synchronization circuits for interfacing with the utility. As a result, these schemes are becoming increasingly popular. However, as the power handled by the converter increases, the power factor deteriorates. To understand quantitatively the cause of poor power factor while negotiating high power loads, large signal models for these schemes are developed. Having understood the cause for poor power factor operation, a modified-OCC-based converter is proposed. This scheme has high power factor while supplying high power loads. Detailed simulation studies are carried out to verify the efficacy of the scheme. In order to confirm the viability of the scheme, detailed experimental studies are carried out on a 3-kW laboratory prototype.     

A Repetitive-Based Controller for a Power Factor Precompensator

In this paper, a repetitive-based controller for a boost-based power factor precompensator is presented. The controller guarantees voltage regulation with a power factor close to unity, despite of the presence of harmonic distortion in the source voltage and uncertainties in the system parameters. It is shown that the repetitive scheme considered here is, in fact, equivalent to a bank of resonant filters, which has shown to be a useful technique in harmonic compensation. Out of this equivalence, a negative feedback structure is obtained for the repetitive scheme which is aimed for the compensation of odd harmonics only. This is in contrast to usual positive feedback repetitive schemes aimed to compensate for all harmonic components. The repetitive scheme consists on a simple feedback array involving a time delay plus a feedforward path, which is simple to implement. The closed-loop stability analysis of such and infinite-dimensional system is performed appealing to the well-known small gain theorem. Experimental results in a 400-W boost-based power factor compensator (PFC), with a fixed-point digital signal processor (DSP)-based implementation of the proposed controller, are provided to assess the performance of the controlled system.     

几种功率因数校正的新方法

介绍了充电泵功率因数校正（PFC）、数字PFC和带PFC的在线UPS的几种新方法。这几种方法不同于传统带PFC控制IC的有源PFC解决方案。     

同期整流的高效率双向PFC电路

提出了一种改善功率因子和抑制高次谐波的单变换功率因子改善 (PFC)电路。它采用双向开关和同期整流 ,得到了高功率因子、高效率和低高次谐波。     

功率因数校正技术的控制策略综述

文章回顾总结了功率因数校正技术的各种控制策略，对比分析了几种典型控制策略的优缺点及其应用场合，展望了功率因数校正技术控制策略的发展趋势。     

大功率单相完全有源功率因数校正器的实现

首先基于现有的、典型的模拟PFC控制芯片,较为详细地描述了单级升压变换的单相AC—DC变换器领域几种基本的有源功率因数校正技术,其中包括传统有源PFC技术、跟随有源PFC技术和单周期有源PFG技术。最后基于PFC控制芯片L4981B详细地介绍了支持较大功率输出的有源PFC电路设计过程,并给出部分实验结果。