A single‐stage LED streetlight driver with PFC and digital PWM dimming capability

This paper proposes a single‐stage light‐emitting diode (LED) driver that offers power‐factor correction and digital pulse–width modulation (PWM) dimming capability for streetlight applications. The presented LED streetlight driver integrates an alternating current–direct current (AC–DC) converter with coupled inductors and a half‐bridge‐type LLC DC–DC resonant converter into a single‐stage circuit topology. The sub‐circuit of the AC–DC converter with coupled inductors is designed to be operated in discontinuous‐conduction mode for achieving input‐current shaping. Zero‐voltage switching of two active power switches and zero‐current switching of two output‐rectifier diodes in the presented LED driver decrease the switching losses; thus, the circuit efficiency is increased. A prototype driver for powering a 144‐W‐rated LED streetlight module with input utility‐line voltages ranging from 100 to 120 V is implemented and tested. The proposed streetlight driver features cost‐effectiveness, high circuit efficiency, high power factor, low levels of input‐current harmonics, and a digital PWM dimming capability ranging from 20% to 100% output rated LED power, which is fulfilled by a micro‐controller. Satisfying experimental results, including dimming tests, verify the feasibility of the proposed LED streetlight driver. Copyright © 2016 John Wiley & Sons, Ltd.     

A universal‐input high‐power‐factor power supply without electrolytic capacitor for multiple lighting LED lamps

The AC–DC power supply for LED lighting application requires a long lifetime while maintaining high‐efficiency, high power factor and low cost. However, a typical design uses electrolytic capacitor as storage capacitor, which is not only bulky but also with short life span, thus hampering performance improvement of the entire LED lighting system. In this article, a SEPIC‐derived power factor correction topology is proposed as the first stage for driving multiple lighting LED lamps. Along with a relatively large voltage ripple allowable in a two‐stage design, the proposal of LED lamp driver is able to eliminate the electrolytic capacitor while maintaining high power factor and high efficiency. To further increase the efficiency of LED driver, we introduced and used the twin‐bus buck converter as the second‐stage current regulator with Pulse Width Modulation (PWM) dimming function. The basic operating principle and the deign consideration are discussed in detail. A 50‐W prototype has been built and tested to verify the proposal. Copyright © 2011 John Wiley & Sons, Ltd.     

一种精确调光的LED电源设计

设计了一种输出电流精确可调的LED电源.系统功率变换部分由PFC和DC/DC两级组成,实现PWM控制输出恒定电流;设计了D/A转换电路和模拟调光电路,将PWM调光信号转换为线性调光电压,实现LED电源输出电流精确可调;采用ATmega8单片机设计了智能调光系统,可以接受RS485总线的调光指令实现256级调光.统测试表明,该电源系统在较大范围内输出电流精确可调,并具有故障检测功能,适合驱动大功率LED路灯、隧道灯.     

A simple LED driver with low dimming switch stress

This paper aims to investigate the low dimming switch stress of a light‐emitting diode (LED) driver. Most dimmable LED drivers contain a series dimming switch with a LED string to implement a pulse‐width modulation‐dimming function. However, this setup causes the dimming switch to suffer from high voltage stress in the dimming interval. To reduce the voltage stress of a dimming switch, a low switch stress scheme is presented. The dimming circuit is parallel with the LED string. Using proper arrangement and design of the parameters, the dimming circuit changes the feedback status, which results in the output driving voltage varying between a constant current and a fixed voltage operation. These two operating conditions also make the LED string turn on/off alternately and consequently and perform the dimming function. The dimming switch acts by altering the feedback path instead of cutting off the main power flow; hence, it does not need a power level switch. Details of the operating principles and design considerations are discussed in this study. A prototype boost converter was developed to verify the feasibility of the proposed low dimming switch stress LED driver. Copyright © 2015 John Wiley & Sons, Ltd.     

An efficient full-bridge resonant converter for light emitting diode (LED) application with simple current control

New power control is introduced in the full-bridge dc-dc converter to drive an LED lamp in this paper. LEDs are semiconductor devices that behave like a constant voltage load with low equivalent series resistance (ESR). Hence, they require precise control for current regulation. In the proposed driver, the LED lamp is driven by two voltage sources connected in series through a series resonant circuit. It processes the majority of lamp power through the full-bridge diode rectifier and supplies small power through a center-tapped rectifier. The LED lamp current is controlled at the selected operating current by using center-tapped rectifier output voltage. In addition, pulse-width modulation (PWM) dimming is implemented. The proposed topology features zero-voltage switching (ZVS), regulation of lamp current, dimming operation, and high efficiency. The working principle, performance, and prototype validation are given for the proposed LED driver.     

单根电力线接入的LED调光器与调光驱动电源

在调查分析现有室内照明LED调光技术和产品的基础上,设计了墙壁开关式的LED调光器与调光驱动电源。为降低对电网的干扰,设计中避免了可控硅导通角控制模式,调光器通过分压方式沿单根电力线(火线)发送2~5 k Hz小幅值(~15 V)电压脉冲调光信号,由驱动电源接收电路检测并解调后改变驱动电路的PWM调光亮度级,调光操作结束后可稳定保持调光亮度级而调光器维持全角导通。调光器工作电流在导通和关断时分别通过单根电力线的电流耦合和分压方式提供,具有静态功耗低、电功率效率和功率因数高、输入电流谐波失真低的特点。     

A buck-boost integrated high gain non-isolated half-bridge series resonant converter for solar PV/battery fed multiple load LED lighting applications

Solar photovoltaic (SPV) or battery fed multiple load LED lighting applications are gaining importance these days, which require independent voltage regulation and dimming control. Half-bridge resonant converters are mostly used due to their simple structure. In this paper, a buck-boost integrated high gain non-isolated symmetrical half-bridge series resonant converter is proposed for multiple load LED lighting applications. With the aid of integrated buck-boost operation, the output voltage can be regulated below and above the nominal input voltage effectively and can produce twice the gain as compared with classical half-bridge converters. Frequency modulation is implemented for output voltage regulation. Pulse width modulation (PWM) dimming has been adopted for illumination control. The proposed driver results in several advantages such as low cost, compact size, improved efficiency due to soft-switching, simple control, independent dimming, and effective operation for multiple loads. Thus, the proposed non-isolated driver configuration is well suited for SPV/battery fed multiple load LED lighting applications. The proposed configuration is tested with single LED load of 22 W and dual-LED loads of 22 W and 43 W. There is an excellent consensus between the simulation and the experimental outcomes.     

Design considerations of an SEPIC PFC converter for driving multiple lighting LED lamps

This paper presents a single‐ended primary inductance power‐factor‐correction converter (SEPIC PFC) for driving multiple lighting LED lamps. With the aid of this converter, high power factor and high efficiency can be achieved by a simple single‐stage circuit with low device stress features. A burst‐mode dimming method is used to regulate the current and brightness of multiple LED lamps. A laboratory prototype is also built and tested. With the prototype, high power factor can remain under universal input voltage operation and individual lamp brightness control. Copyright © 2008 John Wiley & Sons, Ltd.     

LED照明的节能控制技术

阐述了综合LED特性的照明电源,及其振幅控制和脉宽调制（PWM）两种调光控制技术。为实现低功耗、高效率、小型化等性能优势,电源电路中采用了buck．boost型变换器,用于控制LED电流：PWM中采用高频率照明,以抑制图像的闪烁,改善了照明效果。     

基于STC单片机LED智能照明系统的设计

本文介绍了一套LED光源智能调光系统,给出了系统的硬件设计和软件流程图。热释电红外检测器和光敏电阻采集的数据,利用先进的PWM调光技术,通过STC单片机处理后产生PWM信号,控制LED灯可根据环境亮度不同自动调节LED照明的开关和亮度。本系统具有提高用电效率、节约电能以及保护环境的作用。     

LED驱动控制集成电路SSL2108X与应用

SSL2108X是NXP公司新近推出的一系列LED驱动控制高压集成电路,具体有SSL21081,SSL21082,SSL21083,SSL21084和SSL2109几种产品。除SSL2109是MOSFET功率开关管外置,可用于输出功率较大的应用场合外,SSL21081,SSL21082,SSL21083,SSL2108...     

温控触摸型LED工业X射线观片灯

无损检测行业中应用最广泛的是射线检测方法,而观片灯则是射线检测中最常用的设备之一.LED光源具有调光方便简洁,高亮度、寿命长、节能、环保等特点;电容式触摸输入方式工艺成本低、按键美观、寿命长、触摸检测方便和硬件免维护等特点,这些将成为工业观片灯发展的必然趋势.该观片灯选用高亮度LED作为光源,选择可以PWM调光的PT4115作为LED驱动芯片,采用电容式触摸按键作为人机交互,并且带有温度检测装置用于散热风扇的自动调速.电容式触摸按键控制观片灯的工作模式切换和LED的词光,克服了以往以电位器调光易坏的缺陷,因而被广泛应用.     

一种新型的高性能LED驱动电源设计

发光二极管(LED)效率高、寿命长、无污染,在照明领域的应用日趋广泛,但伏安特性的非线性和温度敏感性增加了LED的高性能控制的难度。设计了一种新型的LED驱动电源,主电路采用反激(Flyback)变换器,引入单周期控制(OCC)技术和条件作用技术积分限制抗饱和(Anti-windup)算法分别进行LED的恒压恒流控制,并实现PWM调光功能。仿真结果表明,所设计的电源可有效提高系统的动态品质、稳态精度和抗干扰性能。     

一种智能LED调光控制策略研究

LED照明领域应用调光技术不仅可以进一步减少能源消耗,还可以改善视觉效果.本文设计了一种两级式LED驱动电源,前级Boost变换器实现功率因数校正功能,后级CLCL恒流谐振网络实现LED恒流驱动,针对CLCL恒流谐振网络特性研究了一种智能LED调光控制策略,采用脉冲密度调制对输出电流进行调节,从而实现对LED灯的调光控...     

多路照明LED驱动及调光电路的设计

照明LED正在被广泛的应用,每个LED配有一个单独的驱动源,且灯光不可调,能源浪费,为了多路LED能够随着需要调光,进行实验研究。实验采用的方法是:驱动电路和调光电路独立设置,其中驱动电路采用基于UC3845的单输入-多输出反激变换器来实现,变换器功率为87.5W,它把220V交流市电转换成五路5V直流电,为各自照明LED提供驱动电源;计算机给单片机发出调光信号,单片机控制调光电路对CD4067进行多路选择,同时产生PWM调节LED平均电流值。     

基于AVR单片机的LED自适应调光系统

随着LED照明技术快速发展,对LED自适应调光技术需求更加强烈。该文以AVR单片机中ATmega16作为控制器,利用基于12C（Inter Integrated Circuit）总线的光传感芯片TSL2561采集室内环境光照度,采用脉宽调制（Pulse Width Modulation—PWM）方式调节MOS管,进而调节LED的发光亮度,最终维持室内环境光照度在一个设定的水平。完成了LED自适应调光系统的硬件设计和软件编程,重点介绍了ATmega16通过12C总线读取光传感器芯片TSL2561数据、传感器数据转换为实际的室内环境照度、PWM信号生成等的实现方法。     

LED照明调光设计的方案分析与比较

该文列举了LED照明调光设计的不同方案,经分析和对比得知:EZ Dimming不仅调光性能优（高功率因数、高效率）,而且不需改变接线和硬件,装置成本最低,具有广阔的市场应用前景.     

LED照明灯调光电路的特点及实现方案

对大功率LED驱动电源的几种调光方式做了详细比较,重点阐述模拟调光、PWM调光和TRIAC调光的实现方案,并介绍了TRIAC无闪烁调光的原理。     

A three-leg resonant converter for two output LED lighting application with independent control

A three-leg resonant converter is proposed to drive two light emitting diode (LED) lamps of different power ratings. This may be required when both main and local lighting are essential. The proposed converter is operated simultaneously at two different frequencies. Two series resonant circuits are used to allow two different frequency currents. Each lamp is powered through a series resonant circuit and is controlled independently. LED lamp currents are regulated at the desired operating current by using phase-modulation control and asymmetrical duty ratio control. In addition, pulse-width modulation (PWM) dimming control is implemented for two LED lamps independently. The proposed topology has advantages of zero-voltage switching (ZVS), regulation of lamp currents, independent illumination control, and high efficiency. A 126-W prototype has been developed experimentally to confirm its working principle, performance, and validity.     

Analysis and design of a high power factor, single-stage electronicdimming ballast

This paper presents the analysis, design and practical consideration of a single-stage electronic dimming ballast with unity power factor. The power stage of the ballast is derived from combining a buck-boost power converter and a half-bridge series-resonant parallel-loaded inverter (SRPLI). With the plasma model of the lamp, the analysis of the ballast is carried out, from which the key equations used for dimming control are derived. Starting performance and dimming consideration are also addressed in the paper. In this dimming ballast, both pulsewidth modulation (PWM) and variable-frequency control strategies are employed. The discussed ballast with the controls can save a controller and a switch driver, reduce size and cost, and possibly increase system reliability over conventional two-stage systems in the applications with moderate power level. Simulated and experimental results of the ballast for an OSRAM T8 32-W lamp are used to verify the discussion