皓玥观点

随着LED技术的不断提升,越来越多的照明领域都将凸显LED照明技术带来的革新,功率型LED照明技术在道路照明领域得到了较好的应用和推广,并在很多城市均尝试性 的采用了大功率LED路灯进行改造或新装,并取得了较好的高效、节能、环保的效果,具有巨大的经济、社会和环保效益。     

皓玥观点

LED照明技术经过近几年的快速发展,已进入商业化推广的快车道。而作为照明行业重要组成部分的道路照明在整个国家的照明耗电量中约占20～30％,在国家大力提倡节能减排的形势下道路照明有着巨大的节能空间。致使半导体照明技术在道路照明中的应用将极为可取。一般来说,在LED路灯的开发和推广应用过程中都会遇到以下三方面的问题：二次光学设计、散热设计和光伏系统设计。LED灯具的光学二次设计在整个灯具设计的过程中扮演了非常重要的角色,在整个的灯具的整体设计流程中应该是优先考虑的一环。本文将就此做具体的阐述,以能起到抛砖引玉的作用。     

皓玥观点

功率型LED应用于各种场合的照明通过近几年的业界的共同关注和推进已得到快速的发展,led早已不仅仅局限于指示类应用领域,随着其应用的不断扩大譬如功率型LED路灯、功率型LED隧道灯、功率型筒灯等等都已得到很好的推广应用．但所有这类灯具目前都存在驱动源性能指标不够理想的局面．这就导致灯具的稳定性和可靠性无法得到保障。为此,我们结合自身开发和选用功率型LED恒流驱动源的考虑,希望能与业界共同探讨和引起广泛关注。     

皓玥观点

一个好的产品不仅在性能上和外观上要有好的表现．更重要的是其在市场上的占有率以及其庞大的销售网络和通路的建设与维护。LED从显示类产品过渡到景观装饰类照明产品进而过渡到普通类照明产品，每一个阶段都有相应的销售渠道，而大功率LED照明产品正处在大力推广、试样阶段．应如何更有效的建立市场网络和销售渠道，借助传统照明产品的销售通路加以推广和维护，使得大功率LEO照明产品在“节能减排”方面能产生更好的经济效益和社会效益。     

皓玥观点

不同封装形式的LED由于在光,热、电和结构等方面的差别,适用于不同的应用范围,功率选择适中的多芯片阵列集成封装LED适合应用于户外灯具,例如路灯、隧道灯,应用过程中可以很好的解决二次光学和热设计等问题。     

皓玥之光：大功率高亮度LED光源的创新应用

LED在指示类、景观类、显示类照明已经得到非常成熟的应用。随着LED技术的不断突破,光效从每瓦20～30lm发展到现在每瓦100lm以上,产品不但有质的飞跃,更有了量的突破。LED有着高效、节能、环保、长寿命、维护少、智能化等突出的优点,具有广阔的市场前景和发展空间,将推进照明行业进一步产业升级和带动相关高新技术产业的快速发展,LED照明必将成为21世纪主流光源逐步变为常态化、常规化．而大功率高亮度LED光源将在照明领域占主角。本文从大功率高亮度LED光源在隧道照明的创新应用提点体会。     

新型LED城市道路照明光源及光学系统

由于白光LED具有很多显著的优点，将其应用于公共城市照明设施的替代光源有着许多的优点，然而要真正充分发挥半导体光源的长处，二次光学系统的设计至关重要。本文介绍了一种独特的适用于城市道路照明二次光学系统，他能较好的满足城市道路照明的相关标准，并可以灵活地适用于不同的道路情况。     

高端访谈——大功率LED照明行业执行者说

随着LED芯片技术和封装技术的发展。顺应照明领域对高光通量LED产品的需求,功率型LED逐渐走入市场。而这种LED要真正进入普通照明领域,实现替换现有的日常照明,需要解决的问题还有很多,提高功率型LED光源的可靠性就是很重要的一个方面。     

注重功率型LED二次光学设计

以GaN基功率型蓝光LED加黄色荧光粉合成白光的技术具有生产成本低,器件性能稳定和市场容易接受等优点,是最经济有效的产生自光的技术路线,目前半导体照明几乎全部采用此种技术路线。但是基于传统封装的白光LED器件并不能简单用于照明或代替传统照明光源,原因在于白光LED器件是高亮度、小光通光源。如果在光学上不进行处理,LED的光源会非常眩目,照度均匀性会很差,从而在照明效果上不如传统照明光源,最终导致用户和市场不能接受。     

借光亚展盛会，感受行业脉搏

这是照明行业2007年的盛会，有人盛装出宴；有人轻装上阵。这是照明行业搭建的一台“大戏”，汇聚了光源类、LED、灯饰、配件等风格各异的品类，其中以光源类显得最为眼花缭乱、精彩纷呈，故本刊先呈上“主打戏”——光源类，在其后几期，我们将陆续给大家回放其他戏台的相关情况，敬请关注。[编者按]     

换个角度看LED热

4月25日下午，深圳阳光酒店紫月厅，行业专家、企业和媒体代表欢聚一堂，热情洋溢，召开了一场题为“大热背后的理性呼唤”的研讨会。     

Department performance metrics-a manager's viewpoint

If we view the engineering design activity as a process, and we want to improve that process, then we need a way to measure its results and the trend of those results over time. At the Aeronutronic Division of Lockheed Martin Corporation, we developed and used a set of engineering performance metrics which helped guide our productivity and quality improvement efforts in the Mechanical and Electronic Design Departments. This article describes what we did, how we did it, and offers some advice based on our experience     

The motor designer's viewpoint of an adjustable speed drivespecification

Historically, AC motors have been installed on fixed voltage/frequency power supplies. When motors were specified for these power supplies, it was adequate to specify a few things like voltage, frequency, horsepower, service factor, enclosure, NEMA design, and so on. As demands to reduce energy consumption surfaced, some new features began to be specified, including efficiency and power factor. With the advent of the adjustable speed drive (ASD) and its adjustable voltage/frequency power, new features were again added to those specified-type of load, speed range, and ASD type, to name a few. When specifying a motor for use on an ASD, it is not enough to think about what additional features are required. One must also look at relaxing some of the requirements historically specified. Cost is added and benefits are sacrificed if some of these features are specified when not necessary. The author bases his comments on his own experience, which has been with NEMA frame sizes 182 through 5011-though some of what he says here may be applicable for motors in frame sizes outside this scope     

Kernel feature extraction methods observed from the viewpoint of generating-kernels

This paper introduces an idea of generating a kernel from an arbitrary function by embedding the training samples into the function. Based on this idea, we present two nonlinear feature extraction methods: generating kernel principal component analysis (GKPCA) and generating kernel Fisher discriminant (GKFD). These two methods are shown to be equivalent to the function-mapping-space PCA (FMS-PCA) and the function-mapping-space linear discriminant analysis (FMS-LDA) methods, respectively. This equivalence reveals that the generating kernel is actually determined by the corresponding function map. From the generating kernel point of view, we can classify the current kernel Fisher discriminant (KFD) algorithms into two categories: KPCA + LDA based algorithms and straightforward KFD (SKFD) algorithms. The KPCA + LDA based algorithms directly work on the given kernel and are not suitable for non-kernel functions, while the SKFD algorithms essentially work on the generating kernel from a given symmetric function and are therefore suitable for non-kernels as well as kernels. Finally, we outline the tensor-based feature extraction methods and discuss ways of extending tensor-based methods to their generating kernel versions.     

Searching for profit ? the Microsoft way [viewpoint]

If you can?t beat them, pay their users. That seems to be the latest strategy for Microsoft, which has announced that it will be doing just that to Web surfers who choose to find products using its Live! Search engine.     

On voltage stability from the viewpoint of singular perturbation theory

This paper investigates voltage stability problems based on singular perturbation theory. The application of singular perturbation theory has made it clear that a power system can be approximated by two simplified systems S and F, which respectively correspond to slow and fast subsystems; four types of voltage instability are defined as follows:

• • type I voltage drop, in which the system still has restoring force to its operating point;

• • type II voltage collapse, in which the system loses the capability of keeping its operating point. This is divided into the following:

1. II-1 instability due to dynamic factor with slow responses such as tap-changing transformers, movement of centre of inertia, load changing patterns;

2. II-2 instability due to fast response dynamic factors such as load characteristics, generators, AVR, etc. This kind of instability consists of the following two types:

2.1. II-2S static bifurcation,

2.2. II-2D dynamic bifurcation.

Several features of each type of instability are studied as well as their methods of analysis. Voltage instability tends to begin with type I and then lead to one of the remaining types. The load flow Jacobian can be an effective index to approximately assess types I and II-2S instabilities, while types II-1 and II-2D require direct nonlinear analyses and eigenvalue analyses, respectively. Another point to be noted is concerned with the stability at multiple load flow solutions: it is emphasized that the lower of the multiple load flow solutions can be a stable operating point in some cases, even though most of such operating conditions belong to the type I instability; this situation can occur unless the system encounters the type II instability. The validity of the classification proposed here has been verified through numerical simulations and theoretical analyses which take into account the dynamic characteristics of generating units, loads and tap-changing transformers.     

The efficiency of transmission-line matrix modelling—a rigorous viewpoint

The difference equations of the scalar linear transmission-line matrix (TLM) routine as introduced by Johns for numerically solving the diffusion equation are shown to be isomorphic to Goldstein's correlated random walk model of diffusion. For the infinite homogeneous bar their exact solution is derived algebraically and given in the form of Jacobi polynomials. This puts the TLM algorithm on a sounder mathematical and physical basis. The accuracy in solving the diffusion equation is investigated in general form and thus its astonishing efficiency explained. Several other basic questions of this numerical technique are also discussed.     

Robust current control for boost PFC converters from a sliding mode viewpoint

In this paper, we propose a methodology to derive a pulse‐width modulation (PWM) control for the inner current loop of the boost power factor correction (PFC) converter. The methodology is based on the general sliding mode control theory. It leads to a robust current control that achieves accurate input current tracking under all practical conditions. The design of the control parameters is also presented, which is based on the existence condition and the frequency response analysis. The derived control can be implemented in analog circuitries as an application‐specific controller or as an add‐on feedforward control embedded in standard PFC controller circuits. Copyright © 2010 John Wiley & Sons, Ltd.