基于LLC单级无桥PFC的无频闪LED驱动电源

传统LED驱动电源通常为基于电解电容的两级拓扑结构,其效率较低,寿命周期短;去除电解电容可提高电源寿命,但会带来LED频闪。为此,本文提出一种基于LLC谐振的单级无桥PFC无电解电容无频闪的电源,采用新型无桥PFC拓扑,将其与不对称半桥型LLC谐振变换器集成单级拓扑,从而提高电源效率;为解决无电解电容所带来的LED频闪问题,在单级电源的输出端并联一双向变换器,采用电压电流双闭环控制消除造成LED频闪的两倍频谐波分量。最后,搭建一台144W的实验样机,实验结果验证所提出的单级无桥拓扑及无电解电容方案的有效性和可行性,其最高效率可达93.41%。     

无电解电容LED驱动电源

传统的LED驱动电源中含有大容量的电解电容,由于电解电容寿命短,限制了驱动电源的使用寿命,因此去除驱动电源中的电解电容对于提高电源寿命具有重要的意义。总结归纳了LED驱动电源的去电解电容的技术方法,讨论了其技术性能指标,为LED驱动电源的去电解电容设计提供了参考。     

无电解电容LED驱动电源纹波补偿控制策略综述

随着LED照明领域的不断拓展和人们对健康光源的迫切需要,LED光源的频闪问题备受关注。流经LED光源的纹波电流不但会引起频闪,还会对光度、比色性能和光效等造成不良影响。无电解电容LED驱动电源纹波补偿控制能有效兼顾长寿命和低纹波等性能指标的优化设计,从而为人们提供高效节能且更加健康的LED光源。通过归纳分析无电解电容AC-DC LED驱动电源的关键技术和纹波补偿控制策略,对大功率无电解化LED驱动电源合理化指标要求、拓扑结构、小信号模型、自适应数字电流预测控制、自适应纹波补偿控制和高频能量同步传输控制等进行了展望,并针对工程应用提出了相应的实现思路,以期助推绿色健康LED驱动电源的研究。     

无电解电容AC/DC LED驱动电源中减小输出电流脉动的前馈控制策略

高可靠性、高效率、高功率因数、低成本的LED驱动电源是保证发光二极管(light emitting diode,LED)发光品质和性能的关键。一种无频闪无电解电容AC/DC LED驱动电源已经被提出,它包括一个无电解电容的功率因数校正(power factor correction,PFC)变换器和一个在其输出端并联的双向变换器,式中双向变换器是用来吸收 PFC 变换器输出电流中的低频交流脉动电流,以达到消除LED照明频闪的目的。为了减小双向变换器输出侧的储能电容,储能电容设计为含有较大电压纹波的形式。该文在此基础上,分析双向变换器输出侧储能电容电压大纹波致使双向变换器的占空比中存在相应的谐波成分,其电流内环无法提供这些成分,只能通过增大双向变换器输入电流的跟踪稳态误差来满足这些谐波的需求,最终引起LED驱动电流畸变,会引发频闪问题。为了提高双向变换器输入电流对两倍输入频率交流电流吸收的准确性,减小LED驱动电流脉动,对双向变换器进行稳态分析,提出一种基于电流基准的前馈控制策略,实验结果验证了此方法的正确性。     

一种无电解电容高压大功率LED驱动电源

传统的发光二极管(LED)驱动电源普遍采用电解电容作为储能元件,其相对较短的寿命成为制约LED驱动电源寿命的重要因素。为此,提出采用一种新型的电流型五电平DC-DC电路来搭建LED驱动电源。不仅去除了电解电容,延长了LED驱动电源的使用寿命,还能实现高输入功率因数和恒流驱动LED负载。详细分析了这种LED驱动电源的工作原理以及多电平PWM调制技术。最后基于PSIM仿真环境搭建系统模型,仿真结果验证了LED驱动电源拓扑的可行性。     

无桥填谷式无电解电容LED驱动电源

传统LED驱动电源采用电解电容作为储能电容,但是电解电容严重影响了LED驱动电源的寿命.本文改进了一种无电解电容LED驱动电源电路,不仅消除了电解电容,延长了LED驱动电源的寿命,还降低了储能电容上的电压应力.文中详细分析该拓扑结构的工作原理及开关模态,最后通过实验验证该方案的正确性和可行性.     

一种无电解电容照明LED驱动电源设计

LED本身的长寿命对其相应驱动电源的使用寿命提出了很高的要求,而电解电容严重制约了驱动电源的使用寿命,也就使LED的长寿命变得失去意义。为此,提出一种无电解电容的LED驱动电源方案,与其他无电解电容的LED驱动方案相比,提出的拓扑去掉了电解电容且电路结构简单,还可实现高输入功率因数和负载LED无闪频。论述了这种LED驱动方案的工作原理,进行了实验验证。     

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。     

一种无电解电容的LED照明驱动电源

针对传统发光二极管(LED)照明驱动电源普遍使用电解电容作为储能元件导致驱动电源整体寿命短、体积大的缺点,给出一种基于改进型双Buck-Boost变换器的无电解电容LED照明驱动电源。分析了驱动电源的工作原理与功率解耦电容的电压纹波,制作了70 W实验样机验证了其可行性。     

一种单级低开关应力无电解电容LED电源

传统LED驱动电源中采用电解电容作为储能元件,但电解电容寿命短,限制了整体LED驱动电源的使用寿命.为提高电源寿命,在去除电解电容的基础上,提出一种单级低开关应力电路结构,通过引入由谐振电容与开关管构成的辅助回路,减小开关管开关应力,实现零电压开通,同时反馈漏感能量,提高电源整体效率.分析了该变换器拓扑结构的工作原理,...     

一种高效低纹波调光LED驱动频闪的研究

随着LED照明行业及LED驱动电源技术的发展,具有调光功能的LED驱动电源在LED照明中的应用越来越多,对其调光性能的要求也越来越高。通过对一种高效低纹波调光LED驱动频闪实现方式进行研究,使其既满足LED低纹波电流的要求,又能使LED灯在调光过程中无闪烁、亮度变化均匀柔和,并且可适应不同的调光曲线要求。     

一种高功率因数低纹波LED驱动电源的研究

针对单级LED驱动电源输出电流低频纹波大的问题,提出了一种基于隔离型交错并联Boost变换器的单级高功率因数LED驱动电源。分析了该驱动电源的工作原理以及低频电流纹波的抑制机理,给出了一种将漏感引起的电压尖峰能量反馈到负载侧,抑制输出侧低频电流纹波的控制策略,并进行了仿真验证。最后设计了一台满载功率为100 W的数字控制样机,实验结果验证了所提电路能有效降低LED电流的低频纹波,实现LED的无频闪工作。     

Automatic current‐sharing extendable two‐channel LED driver with non‐pulsating input current and zero dc flux

A 2‐channel LED driver is presented herein, which possesses non‐pulsating input current and automatic current sharing. There are 4 features in the proposed LED driver. First, due to an input inductor, the input current is non‐pulsating, which makes the life of the renewable energy module or input capacitor longer. Second, each coupled inductor winding has a capacitor connected in series. Therefore, the dc magnetizing bias current is zero, and this can improve the iron core utilization, making the core loss and size reduced. Third, the number of LED channels can be extended by increasing windings. Fourth, the LED currents can be almost identical even if there are different LED numbers in LED strings. Eventually, the proposed LED driver is verified by simulation and experiment.     

An electrolytic capacitor‐less LED driver with interleaving flyback topology

Here, we propose a single‐stage alternating current/direct current electrolytic capacitor‐less light‐emitting diode (LED) driver, which applies interleaving flyback topology to reduce the peak‐to‐average ratio of LED driving current. With this approach, the peak current through LEDs is reduced, so the lifetime requirement of LEDs can be satisfied for an electrolytic capacitor‐less LED driver. A new transformer with two interleaving auxiliary windings is applied to this driver. Based on this approach, compared with other electrolytic capacitor‐less LED drivers, an important advantage of this driver is that it can be easily created, without additional control circuits. We will explain the operation principle and control strategy of the proposed driver in detail and will use experimental results taken from a 24‐V 350‐mA prototype to demonstrate its performance. Copyright © 2015 John Wiley & Sons, Ltd.     

一种减少输出纹波的单级反激LED驱动电路

鉴于成本低、效率高等优势,AC-DC单级LED驱动电路可使用单级电路实现输入功率因数校正和输出DC-DC恒流控制,但通常存在较大的输出2倍工频纹波的问题,而电流纹波是影响LED光学特性和寿命的重要指标。首先,提出了一种基于辅助绕组的单级反激LED驱动电路;然后,采用电流纹波抑制策略分析了所提电路的工作原理和实现低输出电流纹波的条件;最后,通过仿真和实验验证了理论分析的正确性和有效性。实验结果表明,所提的LED单级驱动电路能够在不影响输入特性的基础上有效地降低了输出电流纹波。     

Output current ripple reduction of LED driver using ceramic‐capacitor‐input circuit and buck‐boost converter

This article proposes an LED driver that consists of a ceramic‐capacitor‐input rectifier and a buck‐boost converter. The LED driver has an advantage of long life because it does not contain any electrolytic capacitors. However, the issue with electrolytic capacitor‐less LED driver is that the ripple of the smoothed voltage becomes large due to insufficient capacitance of the smoothing capacitor. The proposed method, which uses the discontinuous current mode of a buck‐boost converter, reduces the output current ripple under such conditions. Experimental results using a 5.7 W LED driver prototype demonstrate that the proposed method reduces the output current ripple and that the percent flicker becomes 4.4%, which is smaller than the recommended upper limit of 8%.     

无电解电容器的高功率因数可调光LED驱动器

提出了一个两级LED驱动器,功率级基于传统的PFC＋LLC构架,而该系统与传统结构的最大差异在于没有电解电容器,这延长了驱动器的寿命及提升了系统的可靠性。此外,与市场上现存的大多数LED电源不同,该电源采用直接控制输出电流,这实际上使得驱动器成为一个电流源。,本电源设计也实现了PWM调光功能。直接控制输出电流,能够有效克服温漂带来的缺点,实验结果验证了设计分析的正确性与可行性。一     

LED驱动电路与有关技术要求

LED照明由于具有发光效率高、工作寿命长、启动时间短、使用安全等一系列优点,在室内外照明领域得到了广泛的应用。但是,LED的正向工作电压只有3V—4V,并且正常使用时为得到足够的lm输出,需多只LED串联、并联使用。这就出现了LED负载与驱动电源之间的电压和电流匹配问题。如果两者之间匹配的好则可以有效地发挥LED的性能指标。     

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.