CN105704858B - For two or more parallel strings led lamp drive - Google Patents

For two or more parallel strings led lamp drive Download PDF

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CN105704858B
CN105704858B CN201610128020.6A CN201610128020A CN105704858B CN 105704858 B CN105704858 B CN 105704858B CN 201610128020 A CN201610128020 A CN 201610128020A CN 105704858 B CN105704858 B CN 105704858B
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led
voltage
plurality
slave
power converter
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CN201610128020.6A
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CN105704858A (en
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W·陈
树源·R·许
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香港城市大学
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies
    • Y02B20/30Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
    • Y02B20/34Inorganic LEDs
    • Y02B20/341Specially adapted circuits
    • Y02B20/346Switching regulators

Abstract

一种用于多个LED灯串的LED驱动器,其具有公共节点和用于连接多个LED灯串的多个驱动器输出节点。 A method for a plurality of LED strings LED driver, having a common node and a plurality of driver output node is connected to a plurality of LED strings. 提供主功率电路,该主功率电路具有与公共节点连接的主输出。 Providing a main power circuit, the main power circuit having a main output connected to a common node. 提供多个从属功率电路,所述从属功率电路分别具有与相应的其中一个驱动器输出节点连接的从属输出。 A plurality of slave circuits providing power, the slave power circuits where the slave has a respective output of a driver connected to the output node.

Description

用于两个或多个并联LED灯串的驱动器 For two or more parallel LED strings drive

[0001] 本申请为2010年11月5日提交、题为“用于两个或多个并联LED灯串的驱动器”、申请号为201080071063.6的分案申请。 [0001] The present application is a 5 November 2010 filed, entitled "two or more parallel LED strings of Drives", Application No. 201080071063.6 of divisional applications.

技术领域 FIELD

[0002] 本发明涉及LED驱动器电路,且具体地涉及用于并联LED灯串的驱动器电路及驱动并联LED灯串的方法。 [0002] The present invention relates to a LED driver circuit, and in particular relates to a method for parallel LED string and driver circuits driving parallel with the LED string.

背景技术 Background technique

[0003] 由于固态照明技术上的快速发展,发光二极管(LEDs)已在液晶显示器、标牌及通用照明中获得广泛应用。 [0003] Due to the rapid development of solid-state lighting technology, light emitting diodes (LEDs) has been widely used in liquid crystal displays, signs and general lighting. 与现有的普通发光源(诸如白炽灯和荧光灯)相比,由于不存在灯丝的高场溅射,LEDs具有80,000-100,000小时的相对较长的工作寿命。 Compared with the conventional ordinary sources (such as incandescent and fluorescent lamps), high-field since there is no filament to sputtering, 80,000-100,000 hours LEDs having relatively long working life. 市场上销售的LEDs 现在用较少的玻璃密封,这使得对于操纵者而言它们的可靠性和安全性得到明显改善。 LEDs now on the market with less glass sealing, which makes for the operator in terms of their safety and reliability are improved. 由于不含有毒的汞,LED在其寿命尽头可以被安全地处置。 Being free of toxic mercury, LED can be safely disposed of in the end of its life. 其它的诸如无闪烁、平滑调光、低压工作和现色性良好等有利特点使得LED成为一项新兴的技术,其在不久的将来会在照明市场上占据主要地位。 Others, such as flicker-free, smooth dimming, low voltage operation and excellent color rendering and other advantageous features make the LED becomes an emerging technology, which will occupy a dominant position in the lighting market in the near future.

[0004] 广义的光一电一热(PET)理论指出,与单芯片高功率设计相比,使用低功率芯片的设备级多芯片设计具有功效更高和结温更低等有利特点。 [0004] a generalized optical power of a hot (PET) theory that compared with high-power single-chip design, multi-chip device level using low-power chips having greater efficacy and lower junction temperatures and other favorable characteristics. 类似地,在系统级上,与系统功率相同的由数量较少的高功率LEDs构成的集中式系统相比,基于多个功率相对低的LED的分布式LED系统具有类似的优点。 Similarly, at the system level, the system less centralized system power by the same amount of high-power LEDs configuration compared to the relatively low power LED plurality of distributed systems based LED having similar advantages. 由于LED为电流驱动的设备且其发光强度与施加的正向电流直接相关,因此在驱动多个LED时,串联结构要优于并联结构,因为串联灯串中的所有LED可以在相同电流下工作,而不存在电流共用和色品变化问题。 Since the LED driving current for the device and its light emission intensity is directly related to the forward current is applied, so when a plurality of LED driver, a series arrangement of a parallel configuration is superior, because all the series of LED strings can be operated at the same current , without the current change in the common problems and chromaticity. 然而,串联连接的LED数量在很大程度上受到电源提供的输出低压的限制,因此并联的LED灯串特别适用于高功率应用(即>25W)。 However, the number of serially connected LED by the output of the low-voltage power supply is limited to a large extent, and therefore parallel LED string is particularly suitable for high power applications (i.e.,> 25W). 由于LED的制造公差、老化和温度变化,这种并联LED灯串结构会引发电流失衡问题, 从而导致发光强度和颜色变化。 LED due to manufacturing tolerances, aging and temperature changes, this structure parallel LED strings cause current imbalance, resulting in light emission intensity and color variation. 此外,当在无电流共用装置的情况下使用并联LED灯串时, 即使各个LED灯串的平均电流小于额定电流,某个或多个LED灯串也可能超出其最大绝对额定电流。 Further, when the LED strings in parallel in the absence of current sharing device, even if the average current of each LED string is less than the rated current, one or more LED strings may exceed the absolute maximum rated current.

[0005] 存在数种用于驱动并联连接的多串LED的电流共用法。 [0005] There are several current sharing of multiple LED strings are connected in parallel for driving method. 一种直接的方式是使用与各LED灯串串联的镇流电阻器以使电流差最小。 A straightforward way is to use a ballast resistor strings of each of the LED lamps so that the current difference is minimized. 这种方式非常简单;然而,它的工作效率很差,因为在使用的镇流电阻器上会产生非常大的功耗。 This approach is very simple; however, its efficiency is poor, since the use of the ballast resistor may have a very large power consumption. 可以使用无损耗的电容器来替代有损耗的镇流电阻器,以在LED用AC交流电源驱动或者与整流器耦联时减少不必要的损耗。 You may be used instead of the capacitor lossless ballast resistor lossy to reduce unnecessary loss of driving or when the rectifier is coupled with an AC power source in the LED. 这些方法的主要缺陷在于不能精确控制各LED灯串的正向电流。 The main drawback of these methods is the inability to precisely control the forward current of each LED string. 目前,已在各个灯串上使用线性电流调节器来确保良好的电流共用效果,但是电流调节器上要耗费相当大的功耗。 At present, the use of linear current regulator on each light string to ensure good current sharing effect, but the current regulator to spend considerable power. 另一种方式是为各个LED灯串设立单独的电压源。 Another way is for each LED string to establish a separate voltage source. 可以使用一种基于并联或串联输入连接的转换器的模块式功率转换器结构,其中所述转换器具有独立的LED灯串负载。 You may be used based on the modular structure of the power converter in parallel or series connected input transducer, wherein the transducer has a separate load LED string. 独立检测和控制各LED灯串的电流以遵循相同基准。 Independent testing and control current in each LED string follows the same reference. 由于不存在有损耗的镇流电阻器或线性电流调节器,这两种LED驱动器结构具有相对更高的转换效率。 Loss due to ballast resistors or linear current regulators is not present, the two LED drive structure having a relatively higher conversion efficiency. 然而,这种结构复杂且昂贵,因为每个LED灯串都需要一套主电路和控制器。 However, this structure complicated and expensive, since each LED string requires a main circuit and a controller.

发明内容 SUMMARY

[0006] 本发明提供了一种用于驱动多个并联LED灯串的LED驱动器,其具有公共的主功率转换器和并联级联的从属功率转换器。 [0006] The present invention provides a method for driving a plurality of parallel LED strings LED driver, having a common main power converter and a parallel cascade slave power converter. 主功率转换器被用于提供驱动电压的绝大部分,具有电压调节的多个从属转换器模块提供剩余的平衡电压以分别控制各个LED灯串电流。 A plurality of slave converter module main power converter is used to provide most of the drive voltage, the voltage regulator is provided with the remaining balance to control the voltage of each LED string current. 主功率转换器可以受到PffM控制以对LED灯串进行调光。 Main power converter may be controlled to PffM of dimming the LED string. 主功率转换器应提供总输出电压的绝大部分,同时从属功率转换器提供这种电压的剩余少量部分。 Main power converter should provide most of the total output voltage, while the remaining slave power converter provides a small portion of this voltage. 优选但非必要地,主功率转换器提供LED灯串的标称供电电压的百分之九十(90%)。 Ninety (90%) is preferably, but not necessarily, the main power converter providing an LED lamp strings percent of the nominal supply voltage. 关于各LED灯串的电压的剩余百分之十(10%)由从属功率转换器之一提供。 Each LED string on the remaining ten percent (10%) of the voltage supplied by one of the slave power converter. 从属功率转换器调节剩余电压以平衡各并联LED灯串上的电流。 Slave power converter in order to adjust the remaining balance current voltage on each parallel string of LED lamps. 从属转换器可以使用半导体开关(诸如功率M0SFET)或磁放大器以进行开关控制。 Slave converter may use a semiconductor switch (such as a power M0SFET) or magnetic amplifiers for switch control.

[0007] 本发明还提供了通过从单个主功率转换器电路提供灯串供电电压的第一部分和从独立的从属功率转换器提供各个LED灯串的电压的第二剩余部分来驱动两个或多个并联LED灯串的方法。 [0007] The present invention further provides a first portion and a voltage of each of the LED strings separate from a second slave power converter is driven by the remainder of the supply voltage of lamp strings provided from a single main power converter circuit of two or more parallel LED strings method. 独立的从属功率转换器用于各个LED灯串,且该方法包括独立调节剩余的电压部分以平衡各LED灯串中的电流。 Independent slave power converter for each LED string, and the method includes independently adjusting the voltage remaining to balance the current in each part of the LED string.

[0008] 因此,此处公开了一种LED驱动器,该驱动器包括公共节点,多个驱动器输出节点, 其中在使用中,多个LED灯串被连接在相应的驱动器输出节点和公共节点之间,具有与公共节点连接的主输出的主功率电路,以及多个从属功率电路,各个从属功率电路具有与相应的其中一个驱动器输出节点连接的从属输出。 [0008] Accordingly, disclosed herein is an LED driver, the driver includes a common node, a plurality of driver output node, wherein, in use, a plurality of LED strings are connected between the respective output node of the driver and the common node, main power circuit having a main output connected to a common node, and a plurality of slave power circuits, each slave circuit having a power corresponding to where a slave driver output connected to the output node.

[0009] 此处还公开了一种LED驱动器,该驱动器包括公共节点,至少两个输出节点,生成与公共节点连接的主电压输出的主功率电路,至少两个从属功率电路,每个从属功率电路生成经调节的电压输出,经调节的电压输出与相应的其中一个输出节点相连,其中公共节点和其中一个驱动器输出节点之间的驱动电压包括主电压和相应的其中一个从属电压之和。 [0009] Also disclosed herein is a LED driver, the driver includes a common node, the at least two output nodes, generating a primary output voltage is connected to a common node of the main power circuit, power of the at least two slave circuits, each slave power circuit generating a regulated output voltage, regulated voltage output is connected via a corresponding one of the output node, wherein the driving voltage between the common node and the output node of one of the drives includes a primary voltage and a corresponding voltage, and wherein a slave.

[0010] 各从属输出可以与主输出串联连接。 [0010] Each slave can be output in series with a main output connector. 主功率电路和从属功率电路优选被设置成主电压大于任何从属电压,且更优选地比任何从属电压大大约9倍,但是本领域技术人员将认识到,在优选方面,次级电路是独立调节的,因此电压比在使用中可以发生改变。 The main power circuit and the slave circuit is preferably arranged to power the main voltage is greater than any voltage dependent, and more preferably about 9 times greater than any large voltage dependent, those skilled in the art will recognize that, in a preferred aspect, the secondary circuit is independently adjustable therefore the voltage ratio may change in use.

[0011] 主功率电路和/或从属功率电路优选为开关模式电源。 [0011] The main power circuit, and / or the power circuit preferably slave switched mode power supply. 更优选地,功率电路包括具有变压器的正向转换器,所述变压器具有第一和第二次级绕组,其中主功率电路连接第一次级绕组,各从属功率电路连接第二次级绕组。 More preferably, the power circuit comprises a forward converter having a transformer, the transformer having a first and a second secondary winding, wherein the main power circuit connected to a first secondary winding, each of the slave circuits connected to the second power secondary winding. 各从属功率电路可以具有半导体开关(诸如功率M0SFET)或磁放大器,以及反馈电路以独立调节各从属功率电路。 Each slave circuit may have a power semiconductor switches (such as power M0SFET) or magnetic amplifier, and a feedback circuit to the power circuit independent adjustment of each dependent. 初级电路连接变压器的初级绕组,且包括PWM控制开关以调节初级绕组的功率。 A primary circuit connected to a primary winding of the transformer, and comprises a PWM control to adjust the power switch of the primary winding.

[0012] 本发明的其它方面将从下面描述中变得显而易见,所述描述只是以举例方式给出以说明本发明的具体实施例。 [0012] Other aspects of the invention will become apparent from the following description, the description is given by way of example to illustrate particular embodiments of the present invention.

附图说明 BRIEF DESCRIPTION

[0013] 现在将参见附图描述本发明,其中: [0013] will now be described with reference to the drawings of the present invention, wherein:

[00M]图la、Ib和Ic是用于减少并联LED灯串中电流失衡的二种现有技术方法的不意图; [00M] FIG. La, Ib and Ic are not intended for reducing two kinds of prior art methods string current imbalance parallel LED lights;

[0015] 图2a是根据本发明的LED驱动器的示意图; [0015] FIG 2a is a schematic diagram of an LED driver according to the present invention;

[0016] 图2b是LED驱动器的电压输出的图示; [0016] FIG. 2b is a diagram illustrating the voltage output from the LED driver;

[0017] 图3是LED驱动器的电路图; [0017] FIG. 3 is a circuit diagram of a LED driver;

[0018] 图4示出了LED驱动器的Lf—Vm曲线; [0018] FIG 4 illustrates an LED driver Lf-Vm curves;

[0019] 图5是具有PffM调光的、根据本发明的LED驱动器的第二实施例的电路图; [0019] FIG. 5 is a PffM dimming circuit diagram of a second embodiment of the LED driver of the present invention;

[0020] 图6是具有PSPffM调光的、根据本发明的LED驱动器的第三实施例的电路图; [0020] Figure 6 is a PSPffM dimming circuit diagram of a third embodiment of an LED driver according to the invention;

[0021] 图7示出了对于(a)匹配的LED灯串和(b)失配的LED灯串,以根据本发明的LED驱动器为例的初级开关电流Ip和次级整流器电压Vr、Vrl、Vr2和Vr3的波形; [0021] FIG. 7 shows that for (a) matching the LED string and (b) a mismatch LED strings, the LED driver in accordance with the present invention is an example of a primary current Ip and the secondary switching rectifier voltage Vr, Vrl , Vr2 and Vr3 waveform;

[0022] 图8示出了在(a) 100%、(b) 80 %、(c) 50 %和(d) 20 %的传统PffM调光操作下,测量得到的关于根据本发明的LED驱动器实例的LED灯串电流波形; [0022] FIG. 8 shows (a) 100%, (b) 80%, on an LED driver according to the present invention, the (c) 50% and (d) 20% of the conventional PffM dimming operation, measured LED string current waveform example;

[0023] 图9示出了在(a) 80%、(b) 50%和(c) 20%的PSPffM调光操作下,测量得到的关于根据本发明的LED驱动器实例的LED灯串电流波形; [0023] FIG. 9 shows (a) 80%, (b) 50% and (c) a 20% PSPffM dimming operation, LED string current waveform on example of an LED driver according to the present invention is measured ;

[0024] 图10示出了根据本发明的LED驱动器实例与现有技术的多输出磁放大器调节的驱动器之间的效率比较;以及 [0024] FIG. 10 shows a comparison between the efficiency of an LED driver according to the present invention, examples of adjusting the magnetic amplifier prior art multi-output driver; and

[0025] 图11是用于与红色、绿色和蓝色(RGB) LED灯串一同使用的根据本发明的LED驱动器的第三实施例的电路图。 [0025] FIG. 11 is a circuit diagram of the red, green and blue (RGB) LED light string for use with a third embodiment of the LED driver of the present invention.

具体实施方式 Detailed ways

[0026] 在详细描述本发明的实施例之前,应认识到本发明的应用不限于下列描述中提出或附图中示出的结构细节。 [0026] Before embodiments of the present invention will be described in detail, it should be appreciated that the present invention is not limited to the application presented the details of construction or shown in the drawings in the following description. 本发明能够具有其它实施例,并且可以以各种方式实施或实现。 The present invention is capable of other embodiments and of being practiced or carried out in various ways. 还应认识到,此处使用的用语和术语是描述性的,不应被视为限制性的。 It should also be appreciated that the phraseology and terminology used herein are descriptive and should not be regarded as limiting.

[0027] 本发明提供了一种用于并联LED灯串的驱动器,其具有用于所有LED灯串的“公共” 主电压源(Vm)和用于各LED灯串(SI,S2. .Sn)以进行电流调节的独立从属电压源(Vsl-Vsn),如图2a中所示。 [0027] The present invention provides for a parallel drive of the LED string, which has a LED light string for all the "public" master source voltage (Vm), and for each of the LED strings (SI, S2. .Sn ) to adjust a current dependent voltage source independent (Vsl-Vsn), shown in Figure 2a. 参见图2a和图2b,各灯串中消耗的功率的大部分由“主”电压源(Vm)馈送,而相应的从属电压源(Vsl,Vs2〜Vsn)用于调节各LED灯串(SI,S2…Sn)中的电流以便电流平衡。 Referring to FIGS. 2a and 2b, the majority of the "master" source voltage of the power dissipated in the string each lamp (Vm) is fed, while the respective dependent voltage source (Vsl, Vs2~Vsn) for adjusting each of the LED strings (SI , current S2 ... Sn) in order to balance the currents. 为避免更大的功耗,所有主直流源和从属直流源应为开关模式的转换器。 In order to avoid more power, all of the main current source and a direct current source should slave switch-mode converter. 这对于具有宽的设备参数公差的LED而言是非常重要的。 It is very important for the LED having a wide tolerance in terms of device parameters. 例如,在45mA下,8个LED灯串的正向电压会在21.9V — 31.7V之间变化。 For example, at 45mA, 8 LED strings will forward voltage 21.9V - vary between 31.7V. 如果使用线性电流调节器,正向电压最小的灯串的线性电流调节器两侧的压降将高达9.8V,在正向电流较大的情况下,电流调节器上的功耗是不可接受的。 If a linear current regulator, the minimum pressure drop across the forward voltage of the light string up to the linear current regulator 9.8V, the forward current is large, the power consumption of the current regulator is not acceptable . 例如,典型的〇. 3A的灯串电流将在各个灯串上导致约3W的功耗。 For example, a typical square. 3A string current will cause the string about 3W in the power consumption of each lamp. 根据所提出的LED驱动器结构,可以在各个灯串中建立为所有8个灯串公用的20V主源和覆盖并联LED灯串之间压差的独立低压从属电压源。 The LED driver of the proposed structure, can be established in each light string is a string of common source 20V main cover all eight lights and LED strings in parallel to the pressure differential between the low pressure dependent voltage source independent. 因此,大部分功率由主源提供,只有剩余功率由相应的从属源提供。 Thus, most of the power provided by the main source of power only remaining source provided by the respective dependent.

[0028] 在本发明中可以使用各种具有多个独立输出的布局。 [0028] In the present invention, it may be used in a variety of layouts having a plurality of independent outputs. 然而,对于商业应用而言,驱动器应优选满足以下技术要求: However, for commercial applications, the drive should preferably meet the following requirements:

[0029] 1)电隔离:在主源和从属源之间需要电隔离,因为它们的终端不能共用相同的接地。 [0029] 1) electrically isolated from: electrical isolation is required between the master source and the slave source, because they can not share the same ground terminal. 然而,在从属源之间不必进行电隔离。 However, between the source need not be electrically isolated from the slave.

[0030] 2)经调节的输出:LED灯串两端的电压应进行调节以适应不同正向电流和环境温度。 [0030] 2) a regulated output: LED lamp voltage across the string should be adjusted to accommodate different ambient temperature and forward current. 因此,优选经独立和精确调节的多个输出; Thus, preferably by a plurality of separate and precisely regulated output;

[0031] 3)模块化:这种布局优选是容易扩展的,因此优选模块式方式。 [0031] 3) Modular: This arrangement is readily scalable preferably, it is preferred modular embodiment.

[0032] 4)功率分配:大部分的LED功率应由主源提供,且剩余功率由从属源提供。 [0032] 4) power distribution: most of the power LED should provide the main source, and the remaining power is supplied by the dependent source. 该电路的实施方式应实现这种功率分配。 Embodiments of the circuit should be implemented such power distribution.

[0033] 基于这些考虑,图3中示出了LED驱动器布局的第一实施例,其具有磁放大器(mag-amp) 后级调节器。 [0033] Based on these considerations, FIG. 3 shows a first embodiment of LED driver arrangement having a magnetic amplifier (mag-amp) after stage regulator. 磁放大器后级调节器布局具有效率高、稳定性高、功率密度高、控制简单和电磁干扰低等特点。 After magnetic amplifier stage regulator arrangement having a high efficiency, high stability, high power density, simple control and low and electromagnetic interference. 然而应注意到,基于功率半导体开关(诸如MOSFET而非磁放大器)的标准开关模式功率调节器也可以用于图3中的从属后级调节器。 However, it should be noted that a standard switch-mode power regulator based power semiconductor switch (such as a MOSFET, rather than magnetic amplifier) ​​can also be used after the slave stage regulator 3 in FIG. 只需要变压器的两个次级绕组Nsl和Ns2来生成多个(两个以上)输出。 It requires only two secondary windings of the transformer and Ns2 Nsl generating a plurality (more than two) outputs. 一个次级绕组Nsl的输出用于主源Vm,其受到初级侧上的功率转换器的PWM控制。 A secondary output winding Nsl primary source for Vm, which is subjected to PWM control of the power converter on the primary side. 另一次级绕组Ns2的输出被用于通过检测LED正向电流基于具有反馈回路vl、v2的独立磁放大器调节器Lml、Lm2生成多个从属源Vsl,Vs2···,Vsn (图3 中只示出两个从属源,但是更多的源可以被用于更多的LED灯串)。 Another output of the secondary coil Ns2 is based on having a feedback loop vl, v2 independent magnetic amplifier regulator Lml, Lm2 Vsl sources generating a plurality of slave LED forward current by detecting, in Vs2 ···, Vsn (FIG. 3 It shows two slave sources, but more may be used more source LED string). 值得注意的是,本发明的结构的两个优点是:首先,只需要两个次级绕组来生成多个输出,从而形成更为简单的变压器结构、更低的生产成本和更少的漏感;其次,各个磁放大器调节器Lml、Lm2只被用于处理各个LED灯串上的小部分功率,因此磁放大器芯的尺寸要小很多并且其功耗较低。 Notably, two advantages of the structure of the present invention are: First, only two secondary windings to generate a plurality of output, so as to form a simpler transformer structure, lower production costs and less leakage inductance ; secondly, the respective magnetic amplifier regulator Lml, Lm2 is used only for processing small portion of the power on each LED string, the size of the core magnetic amplifier is much smaller and lower power consumption.

[0034] 磁放大器调节器为各LED灯串上的部分功率提供功率调节功能。 [0034] The magnetic amplifier regulator provides power regulation for the portion of the power on each LED string. 如果灯串电流Iol 大于参考电流Iref,则磁放大器电感Lml的阻断持续时间将通过调节重置电路的输出而增加,使得Vsl下降及Iol相应减小以符合Iref。 If the string current Iol is greater than the reference current Iref is, the inductance of the magnetic amplifier Lml blocking duration will be increased by adjusting the output of the reset circuit, so that the loss and Vsl Iol corresponding reduction in compliance Iref. 如图3中所示,可以看到为各LED灯串提供的功率由两部分构成,即主源和独立的从属源。 As shown in FIG. 3, it can be seen as the power of each LED string provided consists of two parts, i.e. the main source dependent and independent sources. 如果LED灯串的正向压降恒定,则在主源和从属源之间存在无数种分布组合。 If the forward voltage drop of the LED string constant, there is a myriad of composition distribution between the master source and the slave source. 因此,在此将定性分析如何找到最佳的分布。 Therefore, in this qualitative analysis of how to find the best distribution.

[0035] A.功率分布 [0035] A. Power Distribution

[0036] 首先,在所有工作状态下,主源的电压必须低于LED灯串的所有正向压降,因为主源应提供所有LED灯串的功率的绝大部分(但非全部),即Vm〈Vled_min。 [0036] First, in all operating conditions, the main source voltage must be lower than the LED string forward voltage drop of all, because the main light source LED strings shall provide all of the power of the majority (but not all), i.e., vm <Vled_min. 从属源应当能够调节LED灯串两端电压部分以调节它们的正向电流。 Slave should be able to source voltage across LED string adjusting section to adjust their forward current.

[0037] 其次,主源越低,从属源则越高,因为它们的总和应等于整个LED灯串两端的电压。 [0037] Next, the lower the primary source, the higher the subordinate source, because they should be equal to the sum of the voltage across the entire LED string. 在极端情况下,如果主源电压为零,则所提出的电路简化成常规的具有多个输出的转换器, 在这种情况下,各LED灯串完全由单个源供电。 In the extreme case, if the main source voltage is zero, the proposed circuit is reduced to a conventional converter having a plurality of outputs, in this case, each of the LED string is completely powered from a single source. 在这种极端情况下存在两个缺点。 There are two drawbacks in this extreme case. 各个源中的整流二极管的电压压力将明显增大,因此必须使用压降相对较高的高压二极管。 Each voltage rectifier diodes pressure source will be significantly increased, the pressure drop must be used a relatively high voltage diodes. 第二个缺点是,在各个源中需要更大的输出滤波器电感来满足输出电流纹波要求。 The second disadvantage is that, in each of the source output filter inductance requires a larger output current ripple to meet requirements. 除此之外,磁放大器上的功耗将增大,因为它必须阻断对于整个LED灯串而言足够高的电压。 In addition, the magnetic amplifier increases the power consumption, since it is necessary to block the entire LED string sufficiently high voltage. 在本发明中, 公共功率源为所有LED灯串提供主要电压。 In the present invention, all the LED string provides the primary power source for the common voltage. 因此,可以为从属源选择诸如Schottky二极管的具有低额定电压和低正向压降的功率二极管,以及更小的输出滤波器电感。 Thus, such selection may be dependent source having a low rated voltage and a low forward voltage drop of Schottky diode power diode, and a smaller output filter inductor.

[0038] 在该分析中,假定所有LED灯串共用相同电流和具有相同的正向压降VF,且所有灯串电流的总和为IF。 [0038] In this analysis, it is assumed that all the LED strings share the same current and have the same forward voltage drop of the VF, and the sum of all of the string current IF. 所有输出滤波器电感电流被假设具有相同的纹波电流因子γ。 All the output filter inductor current is assumed to have the same current ripple factor γ. 对于各LED灯串完全由单个源提供功率的场合而言,每个输出中需要的输出滤波器电感为: For each of the LED string is completely provided by a single power source case, the output of each output filter inductor is required:

[0039] [0039]

Figure CN105704858BD00071

[0040] 其中D为次级绕组中电压脉冲的占空度,Ts为次级绕组中电压脉冲的开关周期,η 为LED灯串的数量。 [0040] wherein D is secondary winding voltage of the duty cycle of the pulse, Ts is the switching period of the secondary winding voltage pulses, η is the number of LED lamp strings. 为方便起见,式(1)中的 For convenience, the formula (1)

Figure CN105704858BD00072

的值被定义为α。 The value is defined as α.

[0041] 于是对于所提出的驱动器,主源所要求的输出滤波器电感为 [0041] Thus the output filter inductor drive proposed, as the primary source of the desired

[0042] [0042]

Figure CN105704858BD00081

[0043] 各从属源所要求的输出滤波器电感为: [0043] The dependent claims source output filter inductance:

[0044] [0044]

Figure CN105704858BD00082

[0045] 然后可以获得Lf对Vm的曲线,如图4所示。 [0045] The curve may then be obtained Lf Vm, as shown in FIG. 如果负载具有三个LED灯串,S卩η = 3,设定Vm = O.9VF (即共用的功率源提供输出电压的90%),则在所提出的驱动器中需要一个关于Vm为0.3α的电感,以及三个关于Vsl—Vs3分别为0.1α的电感。 If the load has three LED strings, S Jie η = 3, set Vm = O.9VF (i.e., the common power source providing an output voltage of 90%), it is necessary in the proposed drive Vm is about 0.3α inductance, and three are on Vsl-Vs3 inductance of 0.1α.

[0046] 磁放大器芯上的芯损为: [0046] The core loss of the core magnetic amplifier:

[0047] Pccire= (9.93X10—6) · (f1.57) · (Β1.7。) ⑷ [0047] Pccire = (9.93X10-6) · (f1.57) · (Β1.7.) ⑷

[0048] 方程⑷表明芯损与磁通密度成正比。 [0048] ⑷ equation shows that the core loss is proportional to the magnetic flux density. 在我们的提议中,使用磁放大器芯的从属源的电压远低于LED灯串两端的整个电压。 In our proposal, the use of the core magnetic amplifier dependent voltage source is much lower than the overall voltage across the LED string. 因此,方程(4)从理论上证实在此建议中,磁放大器的功耗也减少了。 Therefore, the equation (4) theoretically demonstrated in this proposal, the magnetic amplifier power consumption is also reduced.

[0049] B ·调光方法 [0049] B · dimming

[0050] 传统上具有两种用于驱动LED的调光技术:幅度模式和PWM模式。 [0050] with two for driving an LED dimming technique conventionally: amplitude and PWM modes. 然而,PWM调光法已在高性能应用(诸如显示屏面)中得到更好地接受,因为LED的电流水平且因而色温可以被保持,而幅度模式则为普通的公共照明应用所接受。 However, the PWM dimming method has been better accepted in high-performance applications (such as a display screen), since the LED current level and the color temperature can therefore be held, and the amplitude pattern was common accepted public lighting applications.

[0051] 在本发明中,可以通过传统的PffM方案和相移PWM (PSPffM)方案来实现调光。 [0051] In the present invention, by conventional PffM programs and phase shift PWM (PSPffM) dimming scheme. 图5 (只示出两个LED灯串)中示出了所提出的具有传统PffM调光功能的LED驱动器系统的电路图,其中Rs 1和Rs2分别为LED灯串S1和S2的电流检测电阻,Q为PffM调光开关,点线方框中的电路为磁放大器的重置电路。 FIG 5 (only two are shown LED string) is shown a circuit diagram of a traditional PffM dimming of the LED driver of the proposed system, wherein Rs 1 and Rs2 respectively, the LED strings S1 and S2 of the current detecting resistor, Q is PffM dimmer switch, the dotted line is a circuit block reset magnetic amplifier circuit. 不同于与线性电流调节器一同使用的传统PWM调光法,在该建议中, 所有的LED灯串只需要一个MOSFET (调光开关),且它不在线性阻抗区工作,而是在饱和区工作。 Unlike conventional PWM dimming method using the linear current regulator together, in this proposal, all of the LED string requires only one MOSFET (dimmer switch), and the linear resistance region which does not work, but in a saturation region jobs. 因此,该调光过程中的电导功耗可以减少。 Therefore, conductance of the dimming power consumption can be reduced in the process. 然而,需要差分放大器(DAl)来检测LED电流信号,因为所有的电流检测电阻不共用公共接地(由于只使用一个调光开关Q)。 However, a differential amplifier (DAl) to detect the LED current signal, since all of the current detection resistor do not share a common ground (since only one dimming switch Q). 将检测的电流信号与Iref作比较以调节磁放大器的重置电流。 The current signal Iref detected by comparing the reset current to adjust the magnetic amplifier. 齐纳二极管Zdl的特殊用途是充当电压变换器,因为转换器的多个输出电压不会与误差信号放大器的电压水平相同。 Zener diode Zdl special purpose is to act as a voltage converter, since a plurality of converter output voltage level is not the same as the voltage error amplifier. 在Q关闭期间,初级主开关的高频开关操作可以被停止以进一步降低开关损耗。 During closing of the Q, the high frequency switching operation of the primary master switch may be stopped to further reduce switching losses. 如果调光开关Q被短路,则可以通过调节电流参考值Iref来实现幅度模式调光。 If the dimmer switch Q is short-circuited, may be achieved by adjusting the amplitude of the dimming mode current reference value Iref.

[0052] 为避免传统PWM调光的缺陷(诸如颤动较大的输入/输出电流和退化的EMI性能), 可以采用PSP丽调光功能。 [0052] To avoid the disadvantages of the traditional PWM dimming (such as a larger dither input / output current and degradation of the EMI performance), PSP Korea dimming function may be employed. 图6中示出了所提出的具有PSP丽调光功能的LED驱动器系统,其中每个LED灯串使用一个调光开关。 Figure 6 shows a LED driver system having a dimming function PSP Korea proposed, wherein each LED string using a dimmer switch. 在图6的重置电路中,PNP晶体管(Qrl)被添加到误差信号放大器的输出上。 In the reset circuit of FIG. 6, PNP transistor (Qrl) is added to the output of the error amplifier. 它的作用将在下面解释。 Its role will be explained below. 以LED灯串Sl为例。 Example Sl to LED string. 在Q关闭期间,如果不使用Qrl,则检测到的电流为0且EAl的输出电压较高。 Q current during off Qrl if not used, then the detected output voltage is 0 and the higher the EAl. 这种情形将导致重置电流对于可饱和的电抗器Lml而言过小,Lml将失去其磁放大器功能,Vsl将升高至远高于其期望值。 This situation will result in current is too small to reset the saturable reactor Lml concerned, Lml magnetic amplifier will lose its function, Vsl to be raised well above its desired value. 即,Vsl失去控制。 That is, Vsl out of control. 当添加Qrl时,EAl的输出电压近似为0,则Lml的重置电流将增大以阻止来自次级绕组Ns2的电压脉冲。 When adding Qrl, EAl output voltage is approximately 0, the Lml reset current will increase to prevent the voltage pulse from the secondary coil Ns2. 因此,可饱和的电抗器必须被设计成能够承受输入波形的全部伏秒数。 Thus, the saturable reactor must be designed to withstand all the volt-seconds of the input waveform. 在所有PWM调光信号同时较低的情况下,变压器的初级侧上的主开关将被关闭以降低开关损耗。 In all simultaneously PWM dimming signal is low, the main switch on the primary side of the transformer will be closed to reduce the switching losses. 所有PffM调光信号通过Drl — Drn进行或运算以检测该信号。 All PffM dimming signal Drl - OR'ed in detected signal Drn.

[0053] 所提出的LED驱动器的性能通过具有120kHz单端正向转换器的原型来验证,所述转换器具有由20-30V的电压源工作的第三变压器重置绕组。 [0053] LED driver performance to verify the correct proposed prototype through the converter having a single 120kHz, the converter having a transformer reset voltage source by a third winding of 20-30V. 利用三个并联的CREE冷白LED (型号为XREWHT-L1-WG-Q5-0-04)灯串来评估所提出的LED驱动器的性能,其中每个灯串上串联有6个LED。 Using three parallel CREE cool white LED (model XREWHT-L1-WG-Q5-0-04) LED light string to evaluate the performance of the proposed driver, wherein each of the series string of the six LED lamps. 在350mA下,各个LED的典型正向电压为3.3V,且期望的Vm被设为17V。 At 350mA, a typical forward voltage of each LED is 3.3V, and Vm is set to the desired 17V. 电路的关键部件在表1中列出。 The key components of the circuit are listed in Table 1. 电感值通过⑴一⑶确定。 Inductance value is determined by a ⑴ ⑶.

[0054] 表1 [0054] TABLE 1

[0055] [0055]

Figure CN105704858BD00091

[0056] 图7示出了LED驱动器的主要波形。 [0056] FIG. 7 shows key waveforms of the LED driver. 图7 (a)示出了初级开关电流Ip和次级整流器电压Vr、Vrl、Vr2和Vr3的波形。 FIG. 7 (a) shows a waveform of the primary switch current Ip and the secondary rectifier voltage Vr, Vrl, Vr2 and Vr3 to. 可以看到脉冲宽度不一致。 Inconsistencies can be seen that the pulse width. Vr3的脉冲宽度略短于Vrl和Vr2的。 Vr3 pulse width is slightly shorter than the Vrl and Vr2. 测量的电压为Vm= 17 · 06V,Vs I = 1 · 87V,Vs2 = 1 · 88V,Vs3 = 1 · 72V。 Measured voltage is Vm = 17 · 06V, Vs I = 1 · 87V, Vs2 = 1 · 88V, Vs3 = 1 · 72V. 为了证实所提出的LED 驱动器能够调节驱动电压以减少电流失衡,分别向第2和第3个LED灯串添加2.2 Ω和3.9 Ω的电阻,以便在3个LED灯串之中建立夸大的失配状态。 To verify that the proposed LED driver capable of adjusting a driving voltage to reduce current unbalance, respectively string adding 2.2 Ω and 3.9 Ω resistor to the second and third LED light, in order to establish exaggerated mismatch among the three LED strings status. 图7(b)示出了这种状态下的新波形。 FIG 7 (b) shows a new waveform in this state. 如所期望的那样,Vr3的脉冲宽度最宽,因为第3个灯串具有最高的附加电阻;Vr2的脉冲宽度比Vrl的宽,其中Vrl的保持不变。 As expected, the pulse width of the widest Vr3, because the third lamp strings with the highest additional resistance; pulse width wider than Vr2 Vrl, where Vrl remains unchanged. 新测得的电压为Vm=17.06V,Vsl = 1.87V,Vs2 = 2.52V, Vs3 = 2.94V〇 The new measured voltage Vm = 17.06V, Vsl = 1.87V, Vs2 = 2.52V, Vs3 = 2.94V〇

[0057] 图8示出了不同占空度下使用传统PffM调光法(参见图5)测得的LED灯串电流。 [0057] FIG. 8 illustrates (see FIG. 5) as measured using a conventional LED string current dimming method PffM different duty cycle. 当只具有一个调光开关时,通过调节三个从属源的电压能够在不同占空度下关于三个LED灯串获得相同的幅值300mA。 When the optical switch has only one key, by adjusting the three voltage sources can be dependent on three LED strings to obtain the same magnitude of 300mA at different duty cycle. 图9示出了不同占空度下利用PSPWM调光法(参见图6)所提出的LED 驱动器的波形。 FIG 9 shows a waveform of the proposed dimming method using PSPWM (see FIG. 6) of the LED driver at different duty cycle. 同样,实际上在所有这些条件下均获得良好的电流平衡。 Likewise, in fact, we have received good current balance in all these conditions.

[0058] 为进行比较,建立C· -C· Chen,C· -Y· Wu和T · -F· Wu在Proc · IEEE PESC,2006,2949-2955页的“Fast transition current-type burst-mode dimming control for the LED back-light driving system of IXD TV”(其全部内容以参考的方式并入本文)中描述的传统LED磁放大器调节的驱动器。 [0058] For comparison, the establishment C · -C · Chen, C · -Y · Wu and T · -F · Wu in Proc · IEEE PESC, "Fast transition current-type burst-mode 2006,2949-2955 page magnetic amplifier conventional LED dimming control for the LED back-light driving system of the IXD TV "(the entire contents of which are incorporated herein by reference) described adjusting drive. 图10示出了在不同输入电压下,测得的所提出的LED驱动器和传统驱动器的总效率。 FIG 10 shows a different input voltages, the measured total efficiency of a conventional LED driver and drives proposed. 由于使用公共的功率源和磁放大器后级调节器的相对较低的功率处理要求,因此所提出的方案可以实现更高的能量效率。 The use of a common power source and a relatively low magnetic amplifier power stage regulator after processing requirements, and therefore the proposed scheme can achieve higher energy efficiency.

[0059] 对于IXD背光应用,常常使用RGB LEDs以将三种颜色的光混成白光。 [0059] For applications IXD backlight, RGB LEDs are often used to blend the three colors of white light. 然而,红色、绿色和蓝色LED的标称正向电压不同。 However, the red, green and blue LED forward different nominal voltage. 相同制造商的红色LED的正向电压低于绿色和蓝色LED 的,绿色LED的正向电压与蓝色LED的大致相同。 Same manufacturer red LED forward voltage is lower than the green and blue LED, a green LED and a forward voltage substantially the same as the blue LED. 考虑到这些因素,所提出的LED驱动器适于RGB LED应用。 Considering these factors, the proposed LED driver adapted RGB LED applications. 所提出的电路可以被用于这种应用。 The proposed circuit can be used for this application. 在图11中,红色LED灯串由主源提供功率,绿色和蓝色LED灯串由主源和相应的从属源结合起来提供功率。 In Figure 11, the red LED string powered by the primary source, green and blue LED light string joined by the primary source and provides the respective dependent power source together. 绿色和蓝色LED的电流分别由相应合适的从属电压源单独进行调节以便电流共用;然而,红色LED灯串的电流仅由主电压源调节以便电流共用。 Blue and green LED currents are performed by the respective dependent voltage source suitable for individual adjustment of current sharing; however, the red LED string current adjustment only for the current source is shared by the mains voltage.

Claims (13)

1. 一种用于驱动多个并联LED灯串的LED驱动器,该LED驱动器包括: 公共主功率转换器;以及多个并联级联的从属功率转换器,每个从属功率转换器都电连接在所述公共主功率转换器与所述多个并联LED灯串中相应的LED灯串之间; 其中,在使用中,所述公共主功率转换器被配置为提供用于所述多个并联LED灯串中的每一者的驱动电压的主电压,并且多个从属功率转换器中的每一者被配置为向所述相应的LED灯串提供所述驱动电压的从属电压,其中所述驱动电压包括所述主电压和所述从属电压的和,其中所述主电压大于所述从属电压;以及其中所述多个从属功率转换器被配置为调节所述从属电压以平衡所述多个并联LED灯串中的电流。 1. A method for driving a plurality of parallel LED strings LED driver, the LED driver comprising: common main power converter; and a plurality of parallel cascaded slave power converters, each of the slave power converters are electrically connected to between said common main power converter in parallel with the plurality of LED strings corresponding LED strings; wherein, in use, to the common main power converter is configured to provide a plurality of parallel LED light string mains voltage of each of the driving voltage, and each of the plurality of slave power converter is configured to provide a string voltage of the slave driving voltage to the corresponding LED, wherein the drive the primary voltage and the voltage comprises a voltage and the slave, wherein the primary voltage is greater than the slave voltage; and wherein said plurality of slave power converter is configured to adjust the slave voltage to balance the plurality of parallel LED lamp current string.
2. 如权利要求1所述的LED驱动器,其中所述公共主功率转换器被配置为向所述多个并联LED灯串中的每一者提供90%的电压,并且所述多个从属功率转换器中的每一者被配置为向所述相应的LED灯串提供10 %的电压。 2. The LED driver according to claim 1, wherein said common main power converter is configured to provide a voltage to 90% of each string of the plurality of LED lamps connected in parallel, and the plurality of slave power each converter is configured to the corresponding LED string voltage of about 10 percent.
3. 如权利要求1所述的LED驱动器,进一步包括具有变压器的功率转换器,该变压器具有初级绕组、第一次级绕组和第二次级绕组;其中所述公共主功率转换器与所述第一次级绕组连接并且所述多个从属功率转换器中的每一者与所述第二次级绕组连接。 3. The LED driver according to claim 1, further comprising a power converter having a transformer, the transformer having a primary winding, a first secondary winding and a second secondary winding; wherein said common main power converter and said and a first secondary winding connected to each of the plurality of slave power converter connected to the second secondary winding.
4. 如权利要求3所述的LED驱动器,进一步包括与所述变压器的所述初级绕组连接的初级电路,所述初级电路包括脉冲宽度调制控制开关以用于调节至所述初级绕组的功率。 4. The LED driver according to claim 3, further comprising a primary circuit connected to the primary winding of the transformer, the primary circuit comprises a pulse width modulation control switch for regulating the power to the primary winding.
5. 如权利要求3所述的LED驱动器,其中所述功率转换器是倒转转换器或正向转换器。 5. The LED driver according to claim 3, wherein said power converter is a reverse converter or forward converter.
6. 如权利要求1所述的LED驱动器,其中所述LED驱动器进一步包括用于控制所述多个从属功率转换器中的至少一者的饱和的反馈电路。 6. The LED driver according to claim 1, wherein the LED driver further comprises means for controlling said plurality of slave saturated feedback circuit in the power converter of at least one.
7. 如权利要求6所述的LED驱动器,其中所述反馈电路通过检测所述LED灯串中的正向电流来控制所述多个从属功率转换器中的至少一者的饱和。 The LED driver according to claim 6, wherein the feedback circuit for controlling the saturation of the plurality of slave power converters by detecting at least one of the LED light string of forward current.
8. 如权利要求1所述的LED驱动器,其中所述公共主功率转换器受到脉冲宽度调制控制以对所述多个LED灯串进行调光。 8. The LED driver according to claim 1, wherein said common main power converter by pulse width modulation control to the plurality of LED lamp strings dimming.
9. 如权利要求1所述的LED驱动器,其中所述多个从属功率转换器受到脉冲宽度调制控制以对所述多个LED灯串进行调光。 9. The LED driver according to claim 1, wherein said plurality of slave power converters by pulse width modulation control to the plurality of LED lamp strings dimming.
10. 如权利要求1-9中任一项权利要求所述的LED驱动器,其中所述多个从属功率转换器中的每一者包括用于调节或开关控制的磁放大器或功率半导体开关。 The LED driver according to any one of claims 1-9 as claimed in claim 10, wherein said plurality of power semiconductor switches or magnetic amplifiers each slave power converter comprises means for adjusting or switching control.
11. 如权利要求1-9中任一项权利要求所述的LED驱动器,其中所述公共主功率转换器包括开关模式电源。 The LED driver according to any one of claims 1-9 as claimed in claim 11, wherein said common main power converter comprises a switched mode power supply.
12. 如权利要求1-9中任一项权利要求所述的LED驱动器,其中所述多个从属功率转换器包括开关模式电源。 The LED driver according to any one of claims 1-9 as claimed in claim 12, wherein said power converter comprises a plurality of slave switched mode power supply.
13. —种用于驱动多个并联LED灯串的LED驱动器,该LED驱动器包括: 公共主功率转换器;以及多个并联级联的从属功率转换器,每个从属功率转换器都电连接在所述公共主功率转换器与所述多个并联LED灯串中相应的LED灯串之间; 其中,在使用中,所述公共主功率转换器被配置为提供用于所述多个并联LED灯串中的一者的全部电压,及提供用于剩余的多个并联LED灯串中的每一者的驱动电压的主电压,并且多个从属功率转换器中的每一者被配置为向所述相应的LED灯串提供所述驱动电压的从属电压,其中所述驱动电压包括所述主电压和所述从属电压的和,其中所述主电压大于所述从属电压;以及其中所述多个从属功率转换器被配置为调节所述从属电压以平衡所述多个并联LED灯串中的电流。 13. - for driving a plurality of kinds of LED strings in parallel LED driver, the LED driver comprising: common main power converter; and a plurality of parallel cascaded slave power converters, each of the slave power converters are electrically connected to between said common main power converter in parallel with the plurality of LED strings corresponding LED strings; wherein, in use, to the common main power converter is configured to provide a plurality of parallel LED all lamp voltage of one string, and provide the main driving voltage for the remainder of the voltage of each of the plurality of LED lamp strings in parallel, and each of the plurality of slave power converter is configured to the corresponding LED strings provide the voltage dependent drive voltage, wherein said drive voltage comprises a primary voltage and the voltage and the slave, wherein the primary voltage is greater than the slave voltage; and wherein said plurality a slave power converter is configured to adjust the slave voltage to balance the current string of the plurality of parallel LED lamp.
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