白光LED的工频交流电驱动技术方案

由于工频交流电（简称：交流电）是通用照明最常用的电源,具有使用上的广泛性、便利性和廉价性,加之白光LED技术的迅猛发展,其在通用照明领域的应用也更加广泛,因此LED通用照明需要采用交流电来驱动。基于LED的固有特性,目前占主导地位的LED驱动电源主要是各种类型的高频开关恒流电源。伴随高压ACLED的发展,采用交流电驱动技术虽然还存在许多问题,但已经是异军突起,成为新的LED照明技术发展和研究方向。文章主要是从交流电的特性出发,研究采用交流电驱动白光LED的技术方案以及存在的问题,并给出了结论。     

大功率白光LED的应用及其可靠性研究

近年来,LED技术呈现出不寻常的进步,以其高功效、长寿命、多色彩和低能耗,已经开始在很多应用领域担当重要角色。大功率白光LED是半导体照明的关键器件,而能否真正实现其在照明领域的应用,取决于大功率白光LED光效的提高和可靠性问题的解决。对LED可靠性的研究是提高其可靠性的前提和基础,本文从两大方面概述了国内外研究LED可靠性的方法和进展,总结了限制LED可靠性的失效机制。对大功率白光LED灯具的可靠性,提出了自己的观点。     

High‐efficiency UV LEDs using quaternary InAlGaN

High‐efficiency ultraviolet (UV) light sources are very attractive for application to the medical field, white lighting, high‐density memories, and so on. We have demonstrated that 300‐ to 370‐nm UV emission is considerably enhanced by the introduction of several percent of In into AlGaN due to an In‐segregation effect. We fabricated 310‐nm‐band UV LEDs with quaternary InAlGaN emitting layers on a sapphire substrate and obtained submilliwatt output power. We also fabricated 350‐nm‐band InAlGaN‐based quantum‐well LEDs on GaN substrates in order to eliminate the effects of threading dislocations. The maximum UV output power obtained was as high as 7.4 mW under room‐temperature CW operation. The maximum external quantum efficiency (EQE) was 1.1% with an injection current of 50 mA, which is the highest EQE ever obtained for 350‐nm‐band UV LEDs with top‐emission geometry. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(3): 43–51, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20287 Copyright © 2006 Wiley Periodicals, Inc.     

白光LED用于公路隧道照明的设计分析（上）

白光LED作为一种新型固体光源,已经逐渐用于道路照明。一般公路隧道照明设计要考虑众多因素,除了要达到一些道路照明中要求的指标如照度、均匀度等外,还要考虑隧道不同分区之间照明的不同。在白天和夜晚,由于隧道进出口照明与外界光有差异,也由于眼睛对光的适应问题,而需要提供不同的照明方式。本文考虑到白天自然光对隧道照明的影响,对于使用LED照明时,白天和夜晚的隧道照明分别进行设计。基于软件模型,分别设计隧道各个区域的照明,给出隧道照明良好的设计方案,并且对最终隧道照明的内部段进行了中间视觉下的修正。结果说明目前条件下白光LED应用于隧道照明已可达到较好的效果。     

功率型白光LED的实现及应用

白光是一种复合光,要得到白光LED,就必须让几种颜色进行空间混合。该文主要介绍了如何利用目前技术来实现白光LED,简述了各种方法的原理和特点,同时阐述了白光LED的应用领域。随着半导体技术和加工工艺的不断发展,LED的技术参数不断提高,白光LED有望成为下一代照明光源。     

半导体照明的曙光

本文主要介绍了用于指示、装饰照明等LED的发展,对白光LED进行了研究,大功率LED的特点,虽然LED作为普通照明还有一定的距离,但我们已经看到了半导体照明的曙光.     

LED—21世纪照明新光源

本文简要回顾了单色LED的发展和应用，着重叙述了白色LED的开发和作为一般照明光源的应用前景，阐明了LED照明技术对节能和环保的积极影响。     

LED灯管与直管荧光灯在办公室中的照明效果对比

为了对比LED灯管与直管荧光灯在办公室中的照明效果,选择了14间布灯方式和家具布置均相似的办公室分别安装2种光源进行对比测试,其中4间办公室安装长度为1 200 mm、功率为18 W的LED灯管,另外10间办公室安装长度为1 200 mm、功率为32 W的T8直管荧光灯,经过约300 h的运行后,测量办公桌面的照度,结果表明,用LED照明的办公桌面平均照度比用T8直管荧光灯照明的办公桌面照度高,且采用LED灯管能比采用T8直管荧光灯节能43.75%。     

基于“视觉亮度”的白光LED光色性能研究

从＂视觉亮度＂的角度,研究了脉冲驱动和恒流驱动下白光LED的光色性能。实验结果表明：占空比小于70%时,脉冲驱动LED的光通量比直流驱动的低,但是人眼感觉到的＂视觉亮度＂却相等;占空比大于70%时,脉冲驱动下消耗的功率值低于直流驱动的,光通量却高于直流驱动;高脉冲电流驱动下的白光LED的色坐标向等能白光靠近2.5%~4.6%,光谱三原色的蓝色比值增加约为5%,色温也得到明显的提高,从而增强人眼对白光LED发光亮度的刺激响应。同时,运用视觉脉冲响应函数和人眼视觉惰性的特性对Talbot定律做了简单的修正。并结合人眼的感光特性,很好的解释了脉冲驱动能够提高人眼＂视觉亮度＂的现象。     

Development of ZnSe‐based white light emitting diodes with longer lifetimes of over 10,000 hr

We have demonstrated ZnSe‐based white light emitting diodes (LEDs) with longer lifetimes of over 10,000 hr at 14.5A/cm² by introducing an i‐ZnMgBeSe/p‐ZnMgSe double cladding structure, which includes a very thin i‐ZnMgBeSe layer for suppressing electron overflow and a p‐ZnMgSSe layer for efficient p‐type carrier concentration. By adopting the double cladding layer instead of only the conventional p‐ZnMgSSe cladding layer, rapid degradation is suppressed and the lifetime tendency becomes similar to that of the LEDs consisting of a III‐V semiconductor system. The device simulation and the temperature dependence of optical power showed that the i‐ZnMgBeSe layer played the main role in increasing electron confinement. Our experimental data and reliability test results indicate that the suppression of the electron overflow is essential to achieve a long lifetime acceptable for practical use. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 154(4): 42–48, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20285     

LEDs for Solid-State Lighting: Performance Challenges and Recent Advances

Over the past decade, advances in LEDs have enabled the potential for wide-scale replacement of traditional lighting with solid-state light sources. If LED performance targets are realized, solid-state lighting will provide significant energy savings, important environmental benefits, and dramatically new ways to utilize and control light. In this paper, we review LED performance targets that are needed to achieve these benefits and highlight some of the remaining technical challenges. We describe recent advances in LED materials and novel device concepts that show promise for realizing the full potential of LED-based white lighting.      

基于ZD832的通用AC输入无变压器AC-DC恒流LED驱动器

ZD832是一种用于驱动白光或RGB串联LED串的高压无变压器AC-DC恒流驱动器IC。它利用85～125VAC或180～240VAC的通用输入电压操作,产生一个可达30mA的可编程恒定输出电流,能为所有形式因数的LED灯和照明系统驱动直达117个串联LED（@VF=1．8V）。     

Evaluation and Enhanced Use of Light Emitting Diodes for Hydroponics

Hydroponic farming is a viable and economical farming method, which can produce safe and healthy greens and vegetables conveniently and at a relatively low cost. It is essential to provide supplemental lighting for crops grown in greenhouses to meet the daily light requirement, Daily Light Integral (DLI). The present paper investigates how effectively and efficiently LEDs can be used as a light source in hydroponics. It is important for a hydroponic grower to assess the requirement of photosynthetically active radiation (PAR) or the Photosynthetic Photon Flux Density (PPFD), in a greenhouse, and adjust the quality and quantity of supplemental lighting accordingly. A Quantum sensor (or PAR sensor) can measure PAR more accurately than a digital light meter, which measures the light intensity or illuminance in the SI unit Lux, but a PAR sensor is relatively expensive and normally not affordable by an ordinary farmer. Therefore, based on the present investigation and experimental results, a very simple way to convert light intensity measured with a Lux meter into PAR is proposed, using a simple conversion factor (41.75 according to the present work). This allows a small-scale hydroponic farmer to use a simple and inexpensive technique to assess the day to day DLI values of PAR in a greenhouse accurately using just an inexpensive light meter. The present paper also proposes a more efficient way of using LED light panels in a hydroponic system. By moving the LED light panels closer to the crop, LED light source can use a fewer number of LEDs to produce the same required daily light requirement and can increase the efficiency of the power usage to more than 80%. Specifically, the present work has determined that it is important to design more efficient vertically movable LED light panels with capabilities of switching individual LEDs on and off, for the use in greenhouses. This allows a user to control the number of LEDs that can be lit at a particular time, as required. By doing so it is possible to increase the efficiency of a LED lighting system by reducing its cost of the electricity usage.     

白光LED应用于室内照明的分析与探讨

白光LED具有发光效率高、功耗低、寿命长、环保等很多其他传统照明光源无法比拟的优势。因此被认为是取代白炽灯跟荧光灯最具潜力的照明光源。该文根据目前半导体照明的最新研究进展,介绍了GaN基白光LED应用在室内照明领域的发展趋势,从视觉功效、光学参数、封装技术、价格等方面出发,指出了白光LED在日常照明普及过程中的一些主要问题,并对这些问题做了详细的分析与探讨。针对现有可行的解决方法,对发展前景做了进一步展望。     

GaN基LED能效的研究进展

目前GaN已成为制作发光二极管(light emitting diode,LED)的主流材料,GaN基LED在照明和超越照明应用中占有不可替代的重要地位。随着LED外延和芯片技术的提升,LED的能效也得到了快速的提升。本文介绍了影响LED光源能效的因素;叙述了影响LED能效的内量子效率(internal quantum efficiency,IQE)和外量子效率(external quantum efficiency,EQE)的提升技术,阐述了GaN基LED能效的提升进程,最后对LED能效的未来发展进行了总结与展望。     

照明电子技术发展现状

本文着眼于照明技术的研究和应用热点,对当前正在广泛推广的高强度气体放电灯和被视为最有前途的固态半导体照明——LED照明两个领域,结合电力电子技术在这些领域的应用和发展,总结了它们的研究和应用现状并展望了未来的技术研究走向。另外,本文还综述了近年来结合网络技术、通信技术、控制技术和电力电子技术并正在成为研究热点的网络照明技术的现状和最新进展,并对各种照明网络系统的优缺点进行了较全面的对比和分析。     

LED关键参数及其检测技术

主要介绍了LED照明检测中遇到的新问题以及所采取的新技术,分析并探讨了LED的热特性、LED视觉应用中的高显色LED、视网膜蓝光危害富蓝化照明对昼夜节律的影响以及频闪等问题,希望引起业界对LED照明检测技术的重视。     

照明电子技术的发展现状与未来

追求节能、环境友好和生活舒适是时代对照明技术的新要求.现着眼于照明技术的应用和研究热点,对当前正在逐步推广的高强度气体放电灯和被视为最有前途的固态半导体照明--LED照明两个领域,并结合电力电子技术在这些领域的应用和发展,总结了它们的研究和应用现状,并展望了未来的技术研究走向.另外,还综述了近年来结合网络技术、通信技术、控制技术和电力电子技术以及正在成为研究热点的照明系统网络技术的现状和最新进展.     

Current‐fed isolated PFC pre‐regulator for multiple LED lamps with extended lifetime

To emit high‐quality LED light, one or a bin of LED lamp(s) is normally driven by a PWM‐controlled constant current source to minimize device variation and achieve accurate brightness control. Powered from offline AC mains, the front‐end power converters should provide a relatively low DC voltage bus for the inputs of post‐end LED current regulators. To match the long lifetime of LEDs, the whole LED driver (ballast) should work as durably as the LEDs. However, the lifetime of the driver is usually limited by the high‐voltage electrolytic charge storage capacitors used in conventional PFC pre‐regulators. In this paper, our previously proposed resonant current‐fed isolated PFC pre‐regulator is extended to operate in discontinuous conduction mode (DCM). It allows the use of the low‐voltage storage capacitors on the transformer secondary, and therefore extends the overall lifetime of the LED lighting system. A detailed procedure for finding the expected lifetime of the low‐voltage electrolytic capacitor is given. As before, the high‐voltage stress on the main switches, which is typical in current‐fed isolated converters, is reduced substantially by taking advantage of the transformer leakage inductance necessary for resonance. Additionally, high efficiency is ensured by the use of dual non‐cascading structures. Steady‐state state‐space averaging analysis is performed for designing the converter in DCM operation. A prototype converter is built to verify performance of the proposed PFC LED pre‐regulator. Copyright © 2011 John Wiley & Sons, Ltd.     

浅谈白光LED在未来海洋平台照明中的应用

目前,海洋平台的照明设备主要为高压钠灯和荧光灯,随着大功率白光LED的出现,LED照明的高效、节能、环保、长寿等特点,使其作为一种新的光源用于海洋平台照明系统成为可能。本文对目前海洋平台照明系统与LED照明设备进行了对比,分析了白光LED在未来海洋平台作为照明光源的经济性和可行性,并展望其作为新一代绿色环保光源在海上平台照明的应用前景。