宽输入电压范围的软开关四路均流LED驱动器

为了应对LED的不同输入电压等级应用场合,提出了一种具有宽输入电压范围的四路LED驱动器。该驱动器将Buck-Boost结构集成到全桥网络中,通过不同的开关组合工作在不同的模式,从而获得宽增益。采用无源均流方式实现了四路LED输出均流。由于驱动器的工作特性,开关管无需添加无损缓冲电路即可在全范围内实现零电压开通。详细分析了该驱动器的调制策略、工作原理和性能。最后,搭建了一个69 W的实验样机,实验结果表明该驱动器的输入电压范围为17 V~216 V,均流误差低于3.7%,最大效率可达97.8%。

液晶汽车仪表LED背光硬件电路分析与设计

为了使液晶汽车仪表的背光灯在受到外界电气干扰的情况下能够保持稳定的输出电流、亮度不发生变化,对已使用的三种汽车仪表LED背光电路进行了研究和分析,提出了一种稳定性较高的硬件电路设计——仪表LED恒流源电路。该电路可通过调节精密电阻值来调节LED背光灯的亮度,设计方案简单、调整电流便捷、成本较低,在液晶汽车仪表市场中具有较高的应用价值。

基于无源均流的谐振式无桥型Boost LED驱动电源

传统Boost功率因数校正变换器的输出电压必须大于输入电压,在一定程度上限制了其在LED驱动电源中的应用。同时,传统LED驱动电源因输入端整流桥的存在而限制了自身效率的进一步提升。基于谐振式Boost功率因数校正变换器拓扑提出了一种无源均流型无桥Boost LED驱动电源,通过引入谐振式电容均流网络,实现了多路均流输出;通过整流桥的去除,进一步提升了系统的效率。最后,搭建了一台效率可达93.64%的140 W实验样机,验证了理论分析的正确性与可行性。

一种反激式无电解电容LED驱动电路

针对电解电容制约LED驱动电源寿命的问题,提出一种反激式无电解电容LED驱动电路。该电路拓扑由反激电路和辅助电路组成,反激电路用于实现高功率因数及输出恒流,辅助电路由辅助开关管、储能电容和辅助二极管组成,用于平衡脉动形式的输入功率和平直输出功率的差值。详细介绍了所提电路的工作原理,给出了电路关键参数的设计过程,并对电路进行了仿真与分析,最后研制了一台30W的无电解电容LED驱动电源原理样机,实验结果验证了所提电路的可行性。

单级无电解电容LED驱动电路及控制策略研究

为了消除电解电容对LED驱动电源使用寿命的影响,提出一种基于反激结构的单级无电解电容LED驱动电路拓扑及控制策略。该电路拓扑是在反激变换器的输入端串接辅助储能电路,通过控制辅助储能电容的充放电,实现瞬时输入输出功率的平衡,从而抑制输出电流的低频纹波。详细介绍了该电路拓扑的工作原理;结合输出电流低频纹波产生机理,分析了辅助储能电容充放电的控制规律,给出具体的控制实现方法,并对电路关键参数进行设计,最后研制出一台30 W数字控制的单级无电解电容LED驱动电源样机。实验结果表明,所提电路方案辅助储能电容和输出滤波电容均可降至6.8μF,输出电流纹波可降至16%。通过使用薄膜电容代替传统的电解电容,提高了LED驱动电源的使用寿命。

交流驱动无电学接触GaN基Micro⁃LED器件光电特性

针对Micro‐LED器件微型化带来的尺寸效应、高速巨量转移、发光器件与驱动背板的高精度键合等问题,本文通过金属有机化学气相沉积和原子层沉积技术制备了一种垂直结构的交流驱动无电学接触型GaN基Micro‐LED器件,研究了其光电特性。结果表明,器件电路模型可等效为RC电路,随着交流驱动信号频率的增大,器件等效阻抗先快速减小后趋于稳定。当频率固定时,器件I⁃V特性呈线性关系,器件等效阻抗稳定,器件亮度随着驱动电压增大而增强。当驱动电压固定时,器件在16~22 MHz频率范围内达到最大亮度,且亮度随频率增加呈现先上升后下降趋势;此外,由于回路呈电容特性,无电学接触型Micro‐LED器件存在发光延迟效应和电流超前效应。对比传统Micro‐LED器件,无电学接触型Micro‐LED器件与外部电极无电学接触,在交流驱动条件下实现内部载流子复合发光,有望解决Micro‐LED芯片微型化带来的技术难题。

Progressive current degradation and breakdown behavior in GaN LEDs under high reverse bias stress

The progressive current degradation and breakdown behaviors of GaN-based light emitting diodes under high reversebias stress are studied by combining the electrical, optical, and surface morphology characterizations. The current features a typical “soft breakdown” behavior, which is linearly correlated to an increase of the accumulative number of electroluminescence spots. The time-to-failure for each failure site approximately obeys a Weibull distribution with slopes of about 0.67 and 4.09 at the infant and wear-out periods, respectively. After breakdown, visible craters can be observed at the device surface as a result of transient electrostatic discharge. By performing focused ion beam cuts coupled with scan electron microscope, we observed a local current shunt path in the surface layer, caused by the rapid microstructure deterioration due to significant current heating effect, consistent well with the optical beam induced resistance change observations.

一种白光LED电荷泵电路的设计

白光发光二极管(Light-Emitting Diode,LED)具有体积小、功耗低、发光效率高及寿命长等优点,可以用作中小型便携式电子产品的背光源。设计了一种白光LED电荷泵电路,该电路可以根据实时的电源电压值选择电荷泵的增益模式,在1X/1.5X/2X这3种增益模式中依次切换,且输出电压恒定在设定值,为白光LED的稳定发光提供稳定的驱动电压。进行全电路仿真,结果表明,当电源电压从5.5 V逐渐下降到2.7 V时,输出电压都近似为4.5 V,驱动电流约为20 mA。

Design and Verification of a High Performance LED Driver with an Efficient Current Sensing Architecture

A high power buck-boost switch-mode LED driver delivering a constant 350 mA with a power efficient current sensing scheme is presented in this paper. The LED current is extracted by differentiating the output capacitor voltage and maintained by a feedback. The circuit has been fabricated in a standard 0.35 μm AMS CMOS process. Measurement results demonstrated a power-conversion efficiency over 90% with a line regulation of 8%/V for input voltage of 3.3 V and current output between 200 mA and 350 mA.

基于LCL恒流谐振网络的无电解电容LED驱动电路研究

LED驱动器中电解电容寿命较短,与LED灯的长寿命不匹配,限制了LED照明光源的长时间使用。基于LCL谐振变换器的恒流特性,提出一种脉动电流驱动的两级无电解电容LED驱动电路方案。通过将LED电流与功率因数校正PFC(power factor correction)输出电压加权反馈调节PFC输出电压,并使LED灯以脉动电流方式工作,从而减小所需的储能电容大小,提高输出电流的恒流精度。详细介绍了无电解电容LED驱动电路的工作原理和控制策略,给出了关键参数的设计思路。最后设计了一台100 W的原理样机,并进行了实验测试。实验结果验证了所提方案是可行的。

An Improved Non-isolated LED Converter with Power Factor Correction and Average Current Mode Control

A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.

基于频率跟踪的LED数控恒流驱动电源设计

LED驱动器电流的多频率波动会直接影响LED数控设备的寿命,为此,利用频率跟踪技术,优化设计LED数控恒流驱动电源。优化设计变压器和电磁干扰滤波器,变换LED多路恒流电路、箝位电路、输入保护电路以及LED调光控制电路的连接方式,重新设计频率跟踪电路,连接驱动电源电路与设备元件。通过频率跟踪技术,确保电源各组成部分处于同一工作频率。通过LED设备启动、关闭以及调光功能的驱动控制,实现电源驱动程序的优化。根据实验测试结果可知:应用频率跟踪技术后,LED数控恒流驱动电源的电流波动系数降低了0.108,驱动效率提高了41.98%。

LED城市道路照明灯具驱动电源维护方案探索

随着双碳政策的推行、绿色城市的发展,LED光源凭借其功耗低、光效高等优点在城市道路照明中广泛应用。本文主要介绍了LED城市道路照明灯具的应用情况以及维护中存在的问题,简述LED灯具驱动电源技术原理,推荐了LED灯具驱动电源统一的技术要求,探索出一种高效的LED驱动电源维护方案,为LED城市道路照明灯具维护标准化发展提供参考。

LED灯具谐波对核电厂厂用电电能质量影响研究

根据国内标准规范对电能质量和谐波发射限值的要求,介绍了LED灯具的谐波特性及核电厂厂用电电能质量要求,提出了LED应用于核电厂照明系统时电流总谐波畸变率限值宜低于15%,为新建和改造的核电厂照明系统中采用LED灯具提供参考。

LED灯具产品谐波电流的测试方法及其危害

本文通过对即将实施的新版GB 17625.1-2022标准中针对LED灯具产品相关要求的变化进行分析,并结合市场中流通的常见几种LED灯具产品谐波电流测试情况,研究了谐波电流产生的原因及其对电网的危害,希望LED照明设备生产企业能够更加重视,从产品设计阶段进行改进,提高产品质量。

Investigation of electron cyclotron wave absorption and current drive in CFETR hybrid scenario plasmas

The investigation of electron cyclotron(EC)wave absorption and current drive has been performed for the China Fusion Engineering Test Reactor(CFETR)hybrid scenarios using the TORAY code.To achieve the physics goal of the EC system in CFETR,a total of four wave frequency values and nine locations of launching antennas have been considered,and the injection poloidal and toroidal angles have been scanned systematically.The electron cyclotron current drive(ECCD)efficiency of the 170 GHz EC system is quite low due to the wave-particle interactions being located at the low-field side.To optimize the ECCD efficiency,the wave frequency is increased up to 221–250 GHz,which leads to the power being deposited at the high-field side.The off-axis ECCD efficiency can be significantly enhanced by launching EC waves from the top window and injecting them towards the high-field side.The optimized ECCD efficiency atρ=0.32 and atρ=0.4 is 2.9 and 2.2 times that of 170 GHz,respectively.

Optimization of X-mode electron cyclotron current drive in high-electron-temperature plasma in the EAST tokamak

A discharge with electron temperature up to 14 keV has been achieved in EAST.Analysis of the electron cyclotron current drive(ECCD)efficiency at high electron temperature under EAST parameters is presented using C3PO/LUKE code.Simulation results show that the ECCD efficiency of X-mode increases with central electron temperature up to 10 keV and then starts to decrease above 10 keV,at a specific magnetic field and toroidal angle.The efficiency degradation is due to the presence of the third harmonic extraordinary(X3)downshifted absorption at the low field side(LFS);even the cold resonance of X3 mode is located outside the plasma.As the electron temperature increases from 5 to 20 ke V,the X3 absorption increases from 0.9%to 96.4%.The trapping electron effect at the LFS produces a reverse Ohkawa current.The competition between the Fisch–Boozer current drive and the Ohkawa current drive results in a decrease in ECCD efficiency.ECCD efficiency optimization is achieved through two methods.One is to increase the toroidal angle,leading to X2 mode predominating again over X3 mode and the electron resonance domain of X2 mode moving far from the trapped/passing boundary.The second one is to increase the magnetic field to move away the X3 resonance layer from the plasma,hence less EC power absorbed by X3 mode.

高功率因数LED恒流驱动电源的设计

为了保证发光二极管(LED)正常高效工作,提高LED驱动电路的功率因数,以L6561功率因数控制芯片和恒流二极管为基础,设计了一种高功率因数LED恒流驱动电源。从输出电压、负载电流和功率因数三个方面进行实验测试,实验结果表明,在宽电压范围内,该电源的恒压和恒流效果好,功率因数在0.95以上,较好地抑制了电流谐波。

基于并联二次型Buck变换器的无桥LED驱动电源

驱动电源的稳定性和纹波系数是决定LED照明灯频闪和寿命的重要因素.尽管当前已有各种类型的驱动电源,但还是很难满足LED照明灯的技术要求.为此,提出一种采用二次型Buck变换器的驱动电源.该电源以Buck变换器替换整流二极管,通过并联连接构建主电路,并通过输出电压的采样,控制电路的调节,实现开关管的控制.通过理论分析和仿真验证,该电路输出波形的暂态过程时间短,超调量低,输出电流纹波峰峰值仅为输出电流平均值的0.15%,输出无频闪,可实现恒流输出.