基于变频技术的数字调光控制器

提出了一种新颖简单的控制策略来提高在数字调光模式下的CCFL起辉特性.为了延长灯管的使用寿命,在CCFL背光源模块中设计了一种基于变频技术的数字调光控制器.数字调光控制器具有频率可变振荡器结构.在Cadence环境下使用Spectre软件对设计的频率可变振荡器通过了仿真,证明该设计可有效消除背光源模块中的浪涌电流,降低灯管的起辉电压.     

电子镇流器中半桥逆变器与谐振电路的频率匹配

荧光灯与高频电子镇流器的非阻抗匹配性质,导致在负载灯管一端要引入电感电容,以便与电子镇流器阻抗匹配。电子镇流器的设计中,电子镇流器的振荡频率与串联谐振电路的振荡频率必须匹配,否则会引起开关管工作波形异常,开关管也会有更大功率损耗,降低能效,甚至损坏半桥电路开关管器件本身。     

调制小型弧光灯中的声共振

当调制弧光灯中的直流电流时,在断续频率下弧光是不稳定的。在某些频率下这种不稳定性严重得足以使灯熄灭。前些时候研究了使弧光弯向一边和趋向熄灭的主频率与灯管直径和氙灯、氖灯电流的关系。本文介绍了立体腔(资料[1]错误的叫做球形腔)中最低阶声共振的理论论述,这种最低阶声     

IR全新自适应镇流器控制集成电路专攻紧凑型节能萤光灯应用

电源管理技术供应商国际整流器公司(InternationalRectifier,简称IR)推出IR2520D紧凑型节能萤光灯(Compact Fluorescent Lamp,简称CFL)镇流器控制集成电路,它能适应不断改变的电压、频率及灯管状态,有效延长灯管寿命并提高可靠性。一切所需的镇流器功能均整合于单一的8引脚DIP或SOIC封装,有助于减少元件数量、简化电路并提高可靠性。     

影响节能灯启动的因素

灯丝电子发射的良好与否是灯管建立弧光放电的必要条件,灯丝活性降低会明显增加灯管的启动电压。启动电压与灯管尺寸(长度与直径)、气体的种类和压力有关。从启动来说,惰性气体的压力和电极之间距离的乘积,对每一种灯管有一最佳值。在这个值时,启动电压最小。因为     

“天城”牌双管节能台灯维修

故障现象:接通电源后,打开电源开关,灯管无光及闪烁现象。故障检修:此故障一般是启动继电器损坏所致。可先将灯管从管架取下,用小一字螺丝刀将灯管与电源插座处的铝壳边缘撬开,把灯管插头拨下,看到(?)似氖泡的启动继电器。该继电器可采用市售40W日光     

用报废日光灯管制作简易室外天线

取报废未损坏的日光灯管五根,将其中一根平放,其余四根均匀地成直角固定并平放在它的上方,这四根灯管同侧管脚短接后与第五根灯管的一侧管脚相接,然后分别引出两根引线与电视机天线两输入端相接。在室外可用     

影响日光灯管寿命的几个因素

日光灯是一种能量转换器件,接通交流电源后,它将电能转换成紫外线,再由紫外线转换为可见光源。采用日光灯照明与白炽灯相比有诸多优势,如光线柔和、发光强度高、灯管工作寿命长等,日光灯照明目前已广泛应用。日光灯照明比白炽灯电路复杂,电路附件较多,如果某一部件出现故障,就不能正常工作,除了受灯管、镇流器等本身质量影响外,还有电源电压、环境温度等各类因素。下面就影响日光灯工作寿命的几个因素作简单分析。一、日光灯管本身质量的直接影响日光灯管又称荧光灯管,一支灯管由灯丝、灯头和玻璃管组成。玻璃管内壁涂复一层薄而均匀的荧光粉,灯管两端装有     

闪光灯管的业余检测

各类型电子闪光灯是摄影拍摄中理想的辅助光源,而作为闪光灯的重要部件——闪光灯管(也称频闪放电管),在其内部充以惰性气体氙气,在灯管的两端各设置一对电极即阳极与阴极,而在阴极的电极玻壳处又设有触发电极(也称为导电银膏圈)。闪光灯在实际使用中,由于灯管的质量问题及频繁使用,会导致灯管电气性能的变化和下降,从而使闪光管产生早期发黑衰老、灯管漏气、灯管时闪漏闪等问题。发现灯管产生漏闪、发光强度明显不足时,首先检查闪光灯电路在无故障的前提下,再检测闪光管是否出现衰老、触发电极松动脱落、有无接触不良等故障。判断闪光灯管…     

YJ—1型荧光气氛检测仪

本仪器用于定性检验荧光灯内的气体纯度,从而判定灯管的质量.利用两个外电极与灯管壁面相接触,其上施加50或50Hz电源电压,能测出灯管的最低着火电压,并用发光二极管(LED)指示.此电压与灯内气体纯度密切相关,有害杂质气体越多,着火电压越高.     

谐振腔中等离子体灯泡对微波参数的影响

在微波工程应用中,可在微波谐振腔中加载内含易电离物质的无极灯泡,利用微波能量激发灯泡内物质电离并通过粒子的能级跃迁发光。而无极灯泡中电离形成的等离子体会造成微波的相位偏移、振幅衰减、频率偏移等多种效应,并改变谐振腔的谐振频率,为此分析了无极灯泡内的等离子体对微波参数的影响。     

一种高频无极灯驱动装置设计与实现

无极灯是一种新型绿色光源,因其独特的优点正逐步得到推广。文章回顾了无极灯的发光原理,分析了传统高频无极灯驱动装置采用分立元件设计带来的缺点,提出了一种新型的基于IC驱动的高频无极灯驱动装置,并给出了设计模块的原理图。经过测试,本方案给出的驱动装置可以稳定高效地驱动高频无极灯并应用于实际。     

Harmonized strategy for breaking the striations in the fluorescentlamp

A harmonized strategy for breaking the striations in the fluorescent lamp is proposed. The harmonized circuit (HC) presented is a dependent current source and is used to modulate the lamp current by making the amplitudes of the even harmonics nearly the same as the neighboring odd harmonics. The time and frequency responses of the lamp current without and with HC are respectively simulated and experimented for describing the striation behavior. The dimmer system with HC can actually provide better immunity from striation for the lamp during a wide dimming range from 10% to 100%. In addition, the lighting efficiency increases up to 16.2%     

A lamp power control scheme for dimmable electronic ballasts to minimize the temperature effect on the lamp brightness

A hybrid lamp power control scheme for dimmable electronic ballasts is proposed. Apart from adjusting the brightness of the lamp, the proposed method can also minimize the ambient temperature effect on light output. Instead of regulating the lamp current, the proposed method is based on regulating the power supplying the lamp. First, the dimming operation is achieved by regulating the dc voltage at the ballast inverter input. Second, variation of the lamp power (due to the temperature effect) is regulated by sensing the inverter average input current to adjust the switching frequency of the inverter. An 18 W prototype has been built and tested. The lamp power and luminous output of the prototype at the ambient temperature from 5/spl deg/C to 35/spl deg/C have been studied.     

金属卤化物灯的高频点灯和放电稳定化

为了提高金属卤化物灯的光效，将该灯用电子镇流器在高频下燃点，观察到灯的不稳定性，称为音响共鸣现象。为了克服音响共鸣现象，介绍了四种稳定工作的方法：①在超音响共鸣的频率下工作；②在矩形波下工作；③采用适当的调制频率下工作；④采用三次谐波叠加高频正弦波点灯。本文介绍金属卤化物灯用电子镇流器、高频点灯和放电稳定化。     

High frequency electronic ballast provides line frequency lampcurrent

Most electronic ballasts for fluorescent lamps provide a sinusoidal lamp current at the switching frequency. The high-frequency current flowing through the lamp can generate significant radiated noise, which is unacceptable in noise-sensitive applications, such as fluorescent lights in airplanes. Using shielded enclosures for the lamps may solve the problem, but it is expensive. A discontinuous conduction mode (DCM) electronic ballast topology is presented which drives the lamp with line frequency current, just like a magnetic ballast. However, compared to a magnetic ballast, its weight is substantially reduced due to operation at 40 kHz switching frequency. The topology also ensures unity power factor at the input and stable lamp operation at the output     

Design and performance of an electronic ballast for high-pressuresodium (HPS) lamps

An electronic ballast for high-pressure sodium (HPS) lamps was designed and evaluated, theoretically and experimentally. The ballast is based on the half-bridge topology and includes a high-voltage ignitor and dimming capability. It was used to drive and examine the high frequency characteristics of a commercial HPS lamp (NAV-T 150 W (SON-T), OSRAM). The experimental results reveal that, for the frequency range of this study (27-75 kHz), the lamp is free of the acoustic resonance problem. It was also found that, for the present experimental conditions, the lamp is purely resistive, and the resistance is practically independent of the power level and operating frequency. The lamp exhibited stable operation over a very large dimming range, down to about 7% of nominal power. The 2.8-kV ignition pulse was found to be sufficient for both cold and hot startup under the proposed operating conditions     

测量灯罩表面污染程度的电路设计

本文介绍了一种测量灯罩污染程度的电路.信号发生器产生PWM信号给驱动LED的电路,紫外LED灯发出紫外光照到车灯灯罩上,灯罩散射回来的光由滤光片滤除干扰光后,由光电二极管接收并将光强转换成电信号,该电信号送至放大电路,放大电路输出的电压传至选频电路,选出的电信号由整流滤波电路转换成直流电压,该直流电压送至电压比较器,并与电压比较器的阈值比较.当灯罩污染达到一定程度时,电压比较器输出高电平,启动车灯清洗器,清洗干净后,自动关闭清洗器.本设计的目的在于既能保持车灯表面清洁,又能减少对灯罩不必要的清洗,延长清洗器的寿命.     

Dimmable electronic ballasts by variable power density modulation technique

Dimming can be accomplished commonly by switching frequency and pulse density modulation techniques and a variable inductor. In this study, a variable power density modulation (VPDM) control technique is proposed for dimming applications. A fluorescent lamp is operated in several states to meet the desired lamp power in a modulation period. The proposed technique has the same advantages of magnetic dimming topologies have. In addition, a unique and flexible control technique can be achieved. A prototype dimmable electronic ballast is built and experiments related to it have been conducted. As a result, a 36WT8 fluorescent lamp can be driven for a desired lamp power from several alternatives without modulating the switching frequency.     

Dimming Control Characteristics of Electrodeless Fluorescent Lamps

The study described in this paper was undertaken to identify the dimming control characteristics of the electrodeless fluorescent lamp. First, to accomplish this, a model of the electrodeless fluorescent lamp was made. Two kinds of dimming control methods, the variable switching frequency control method and the variable dc-link voltage control method, were then applied to the resulting model of the lamp, after which the results of the application of the two methods on the lamp model were compared. The hypotheses that were initially formulated were confirmed by the results of the experiment that was conducted on the 100-W ENDURA-type electrodeless fluorescent lamp. The results show that the lamp's dimming control of the switching frequency control is nonlinear and that of the variable dc-link voltage is linear over a wide range, and the theoretical value obtained by the proposed model well matches that of the experimental value.