CN203504822U - LED drive - Google Patents

LED drive Download PDF

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Publication number
CN203504822U
CN203504822U CN201320577735.1U CN201320577735U CN203504822U CN 203504822 U CN203504822 U CN 203504822U CN 201320577735 U CN201320577735 U CN 201320577735U CN 203504822 U CN203504822 U CN 203504822U
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China
Prior art keywords
unit
low
pass filter
feed
connects
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CN201320577735.1U
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Chinese (zh)
Inventor
文威
武俊
卞娟
刘伟
马皓
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Zhejiang University ZJU
Opple Lighting Co Ltd
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Opple Lighting Co Ltd
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Priority to CN201320577735.1U priority Critical patent/CN203504822U/en
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Abstract

The utility model discloses an LED drive which comprises a rectifier bridge, a direct current transformation unit, a feed-in unit, a low-pass filtering unit, a signal processing unit and a control drive unit. An input end of the rectifier bridge is connected with an electronic transformer. One end of the direct current transformation unit is connected with the rectifier bridge, and the other end of the direct current transformation unit is connected with an LED load to supplies power to the LED load. The feed-in unit is connected with the direct-current transformation unit. The low-pass filtering unit is connected with the feed-in unit. The signal processing unit is connected with the low-pass filtering unit. One end of the control drive unit is connected with the signal processing unit, and the other end of the control drive unit is connected with the direct current transformation unit. The control drive unit controls the direct current transformation unit according to feedback signals which are acquired by the feed-in unit and transmitted through the low-pass filtering unit and the signal processing unit.

Description

A kind of LED driver
[technical field]
The utility model relates to a kind of driver, especially refers to a kind of LED driver.
[background technology]
Electronic transformer is very extensive in lighting field application, because it is operated in high frequency, compare with traditional silicon steel disc transformer, aspect weight and volume, there iing very large advantage, simultaneously, electronic transformer output is the low-voltage ac voltage of safety isolation, is very applicable to safety to have the occasion of strict demand, as the illumination of market cabinet, hotel room illumination and lighting of home etc.What conventional light source and electronic transformer were supporting is tungsten halogen lamp, general conventional power is about 20W ~ 60W, this is a kind of thermal radiation alight, luminous efficiency is only in 20lm/W left and right, life-span only has 3000 ~ 5000 hours, in spectrum, except visible ray, also contain infrared light and the ultraviolet light of certain ingredients, these limitations restrict the scope of application of tungsten halogen lamp.Increasingly mature along with light-emitting diode (LED) technology and market, the application that substitutes tungsten halogen lamp with LED also more and more comes into one's own.As the representative of solid-state illumination, LED has higher luminous efficiency and longer useful life, meanwhile, does not contain infrared and ultraviolet composition in the spectrum that LED sends, and these advantages are applicable to for replacing tungsten halogen lamp LED very much.
Please refer to shown in Fig. 1, as shown in Figure 1, LED driving power generally includes rectifier bridge and DC converter to the internal structure block diagram of LED driving power.DC converter connects LED load.DC converter has closed loop loop conventionally, and closed loop loop is by forming certain current reference value from the working signal of DC converter feedback, and this current reference value is processed work or the shutoff of controlling afterwards DC converter by signal.After ac square wave input, through rectifier bridge, AC signal is converted into DC pulse signal, because input is ac square wave, make waveform after rectification to drop to zero in each input switching direction moment.Under direct current input condition, in order to realize the quick response to output voltage or electric current, reduce circuit impact on control object when startup, input voltage or load saltus step, guaranteeing under the prerequisite of circuit steady operation, often must be higher loop bandwidth Frequency Design, for example reach switching frequency 1/10 even 1/5, corresponding concrete numerical value can reach 10kHz or more than, so high bandwidth frequency is used for and electronic transformer auxiliary work, but can produce many problems.For example, in input power frequency situation, as 50Hz, because the output of electronic transformer is with twice power frequency envelope, the input and output of LED driving power are unavoidably pulsed with twice power frequency, even if add electric capacity after rectifier bridge, can only reduce twice power frequency composition, cannot eliminate completely.This twice power frequency working signal is through DC transfer circuit, by output, feed back and enter in closed loop loop, can by the identification of high bandwidth loop, also be adjusted immediately, because bandwidth frequency is high more a lot of than twice work frequency, causes current reference value to change feedback according to output twice power frequency and carry out respective change.As shown in Figure 2, when current reference value is too small, electronic transformer can quit work.When electronic transformer is when civil power near zero-crossing point quits work, owing to there is no power stage, the input of DC converter declines, output signal also declines thereupon, the compensating network of closed loop loop is in order to stablize output signal, the corresponding current reference value that improves, like this when electronic transformer restarts, DC transfer circuit will be inputted very high electric current, too high electric current can easily trigger the output overloading protection of electronic transformer, especially the in the situation that of the use in parallel of a plurality of LED driving powers, input current can superpose, affect the stable output of electronic transformer, and current reference value only need to maintain value shown in dotted lines in Figure 2 and just can make electronic transformer work in fact, on the other hand, before and after DC converter input peak value, because current reference value above too high causes too much power stage, the corresponding reduction current reference value of compensating network, cause input current too low, even, lower than maintaining the required current value of the normal work of electronic transformer, electronic transformer can reach the saturated of internal drive magnetic core, output failure of oscillation.Electronic transformer quits work and can by loop, be identified by the output of DC transfer circuit, again improve current reference value, when current reference value is sufficiently high, through the inner start delay time of electronic transformer, electronic transformer is reworked, output square-wave waveform.Because the inner start delay time of electronic transformer is not fixed value, but and mains input voltage instantaneous value and start-up circuit relating to parameters, frequency and the twice power frequency of the adjustment of closed loop loop do not have fixed relationship, final electronic transformer output is very irregular, occur low frequency operation noise and output LED flicker, input power factor also so greatly declines.
Therefore,, in order to overcome above-mentioned defect, be necessary to provide a kind of improved LED driver.
[utility model content]
The purpose of this utility model is to provide a kind of LED driver.
To achieve these goals, the utility model adopts following technical scheme: a kind of LED driver for being connected with electronic transformer, comprises rectifier bridge, DC converting unit, feed-in unit, low-pass filter unit, signal processing unit and control driver element.The input of rectifier bridge connects with electronic transformer.One end of DC converting unit is connected with described rectifier bridge, and the other end is connected to give described LED load supplying with LED load.Feed-in unit is connected with described DC converting unit.Low-pass filter unit is connected with described feed-in unit.Signal processing unit is connected with described low-pass filter unit.Control driver element one end is connected with signal processing unit, and the other end is connected with described DC converting unit.Described control driver element is controlled described DC converting unit according to described feed-in unit collection and through the feedback signal that described low-pass filter unit and signal processing unit pass over.
Preferably, by the signal of exporting after described low-pass filter unit filtering, be low ripple direct current signal.
Preferably, the voltage of the DC converting unit of described feed-in low-pass filter unit is described LED driver input voltage, output current or output voltage.
Preferably, described signal processing unit comprises comparator, and the output of described comparator connects described control driver element, and described comparator is controlled the shutoff of described control driver element.
Preferably, described LED driver also comprises feed-in unit, and the first end of described feed-in unit connects described DC converting unit, and the second end connects described low-pass filter unit.
Preferably, the first end of described feed-in unit connects the output of described DC converting unit, and the output voltage of described DC converting unit is fed back to described low-pass filter unit.
Preferably, the first end of described low-pass filter unit connects described feed-in unit, and the second end of described low-pass filter unit connects the negative pole of the comparator of described signal processing unit.
Preferably, described DC converting unit comprises sampling resistor, and the positive pole of the comparator of described signal processing unit connects described sampling resistor, thereby by the positive pole of comparator described in the peak current feed-in of described DC converting unit.
Preferably, the first end of described feed-in unit connects the input of described DC converting unit, and the input voltage of described LED driver is fed back to described low-pass filter unit.
Preferably, described DC converting unit comprises sampling resistor, and described signal processing unit also comprises signal superpositing unit, and described signal superpositing unit one end connects described sampling resistor, and the other end connects between described low-pass filter unit and described comparator.
Preferably, the signal of described signal superpositing unit and described low-pass filter unit input of comparator described in feed-in after stack, described signal processing unit has reference source, and the negative pole of described comparator connects described reference source.
Preferably, described control driver element comprises control unit, driver element and clock signal transmitter unit, and described clock signal transmitter unit triggers described control unit.
Preferably, described DC converting unit comprises switch element, and described control driver element is controlled work or the shutoff of described switch element.
Compared to prior art, the utility model LED driver has following advantage: can adapt to different electronic transformers.
[accompanying drawing explanation]
Fig. 1 is the internal structure block diagram of LED driving power in prior art.
Fig. 2 is the current reference value change curve of voltage oscillogram after the rectifier bridge of LED driving power of electronic transformer and closed loop loop of arranging in pairs or groups in prior art.
Fig. 3 is the composition schematic diagram of the utility model LED driver.
Fig. 4 is the schematic diagram of the supporting electronic transformer of the utility model LED driver.
Fig. 5 is the change curve of current reference value in voltage oscillogram and closed loop loop after the rectifier bridge of LED driver of the utility model collocation electronic transformer.
Fig. 6 is the circuit diagram of the first embodiment of the low-pass filter unit of the utility model LED driver.
Fig. 7 is the circuit diagram of the second embodiment of the low-pass filter unit of the utility model LED driver.
Fig. 8 is the circuit diagram of the 3rd embodiment of the low-pass filter unit of the utility model LED driver.
Fig. 9 is the circuit diagram of the 4th embodiment of the low-pass filter unit of the utility model LED driver.
Figure 10 is the schematic diagram of the first execution mode of the utility model LED driver.
Figure 11 is the schematic diagram of the second execution mode of the utility model LED driver.
Figure 12 is the schematic diagram of the third execution mode of the utility model LED driver.
Figure 13 is the circuit diagram of the first preferred embodiment of the utility model LED driver.
Figure 14 is the circuit diagram of the second preferred embodiment of the utility model LED driver.
[embodiment]
Please refer to shown in Fig. 3, a kind of LED driver 1 for being connected with electronic transformer of the utility model, comprises rectifier bridge, DC converting unit, feed-in unit, low-pass filter unit, signal processing unit and controls driver element.The input of rectifier bridge connects with electronic transformer.One end of DC converting unit is connected with described rectifier bridge, and the other end is connected to give described LED load supplying with LED load.Feed-in unit is connected with described DC converting unit.Low-pass filter unit is connected with described feed-in unit.Signal processing unit is connected with described low-pass filter unit.Control driver element one end is connected with signal processing unit, and the other end is connected with described DC converting unit.Described control driver element is controlled described DC converting unit according to described feed-in unit collection and through the feedback signal that described low-pass filter unit and signal processing unit pass over.The utility model is incorporated into low-pass filter unit in loop, the voltage feed-in low-pass filter unit of DC converting unit, by low-pass filter unit filtering signal provide current reference for signal processing unit, this current reference is owing to having passed through low-pass filter unit, by filtering low frequency impact, thereby obtain level and smooth current reference value, make when LED driver 1 is when connecting electronic transformer (not shown) uses, electronic transformer can both be stablized output at each power frequency period.The circuit of DC converting unit adopts buck topology, buck topology or Boost topology conventionally, and the input voltage of selective basis LED driver 1 and the relation of output voltage of different topology are determined.In different embodiment, LED driver 1 does not limit for any concrete topology or control circuit, and for example, with regard to topology, reduction voltage circuit, step-up/step-down circuit, booster circuit, Cuk circuit, Sepic circuit etc. are all suitable topological structures.On the other hand, also not limiting is to realize with one-level circuit or two-stage circuit, can just use one-level circuit, and output directly connects LED load, or two-stage circuit, and centre is added with energy-storage travelling wave tube, and rear class output connects LED load.Output feedback variable can be output voltage, or output current.
Please refer to shown in Fig. 4 to Figure 10, Fig. 4 is the electrical connection diagram of LED driver 1 supporting electronic transformer, mains ac power supply, as 220VAC, be connected to electronic transformer input, electronic transformer, by the isolated variable of inner high-frequency circuit (not shown) and transformer primary side and secondary winding (not shown), is exported low-voltage ac voltage V1.
In order to make electronic transformer in the stable output of each power frequency period, the utility model is incorporated into low-pass filter unit in loop design, the impact of filtering low frequency, thus obtain level and smooth current reference value.From the voltage of DC converting unit feedback, enter low-pass filter unit, as shown in Figure 5, the twice power frequency that the current reference value forming through low-pass filter unit can not followed electronic transformer output changes and changes.Because the loop design of low-pass filtering can be adjusted the output valve of a plurality of power frequency periods, thereby guarantee that current reference value remains unchanged in power frequency period.Like this, the output that electronic transformer can be stable, is conducive to improve the compatibility of 1 pair of different electronic transformer of LED driver.Please refer to shown in Fig. 6 to Fig. 9, the circuit of low-pass filter unit can be according to the loop design of actual DC converting unit, and Fig. 6 is to Figure 9 shows that four kinds of more common low-pass filter circuits.Shown in Fig. 6, low-pass filter unit is RC integrating circuit, the principle of utilizing capacitor C two polygonal voltages to suddenly change, and radio-frequency component can be by filtering after after RC integrating circuit.Shown in Fig. 7, low-pass filter unit comprises operational amplifier U1, the resistance R of concatenation operation amplifier in negative pole and the capacitor C of cross-over connection operational amplifier input cathode and output, the anodal a reference source that connects of operational amplifier.Shown in Fig. 8, low-pass filter unit comprises the resistance R 1 of operational amplifier U1, concatenation operation amplifier in negative pole, capacitor C and the resistance R 2 of series connection, the negative pole of one end concatenation operation amplifier of capacitor C, resistance R 2 series circuits, the output of other end concatenation operation amplifier, the anodal a reference source that connects of operational amplifier.Capacitor C and two resistance R 1, R2, produce a zero point and a limit, can make single zero point loop gain increase with frequency logarithm with the slope of+45 °, is conducive to improve phase margin.Shown in Fig. 9, low-pass filter unit comprises resistance R 1, one end concatenation operation amplifier in negative pole, the capacitor C 1 of other end concatenation operation amplifier out and capacitor C 2 and the resistance R 2 of series connection of operational amplifier U1, concatenation operation amplifier in negative pole, the negative pole of one end concatenation operation amplifier of capacitor C 2, resistance R 2 series circuits, the output of other end concatenation operation amplifier, capacitor C 2, resistance R 2 series circuits are in parallel with capacitor C 1, the anodal a reference source that connects of operational amplifier.Two electric capacity and two resistance, produce a zero point and two limits, and wherein second limit can be located near twice work frequency, gain declined more rapidly, the impact that can better cut down twice work frequency.According to different needs, can select the circuit of different low-pass filter units, and the circuit of low-pass filter unit is also not limited only to above-mentioned four kinds.
In LED driver of the present utility model, the voltage of the DC converting unit of feed-in low-pass filter unit can be the input voltage of LED driver, can be also the output voltage of LED driver, can be also between DC converting unit two level frameworks.
Please refer to shown in Figure 10, the voltage of the DC converting unit of feed-in low-pass filter unit is the output voltage of DC converting unit.The output voltage V 1 of electronic transformer is the input voltage V2 of LED driver after rectifier bridge, and the output voltage of DC converting unit is V3.Sampled output signal, the output signal of DC converting unit forms current reference after feeding back to low-pass filter unit.Meanwhile, signal processing unit connects DC converting unit, and the current peak of sampling DC converting unit forms sampled signal.Through the current reference signal of low-pass filter unit and current peak signal formation control signal after signal processing unit of the DC converting unit sampling, thereby control driver element, send cut-off signals.Due to the low-pass filtering adopting, making the current reference forming is steady state value, can because current reference is too small, not affect electronic transformer, causes electronic transformer normally to work.
Please refer to shown in Figure 11, the voltage of the DC converting unit of feed-in low-pass filter unit can be also the input current of DC converting unit.The output voltage of electronic transformer is the input voltage V2 of LED driver after rectifier bridge.Sampling input voltage V2, directly acts on the work of electric current loop, thereby according to the variation of input, changes switching frequency or the duty ratio of DC converting unit, reaches the object of controlling output.Input voltage V2 feedback application is in the loop of generation current reference value, input voltage V2 is after feedback, enter low-pass filter unit, low-pass filtering electric unit bandwidth is less than 100Hz, representative value is about 10 ~ 20Hz, therefore, the output of low-pass filter unit can be equivalent to the mean value (input mean value) of input voltage V2, and the size of this mean value is relevant with electronic transformer output waveform.Input mean value is connected to signal processing unit.LED driver comprises the current reference value 1 of FD feed processing unit, signal processing unit according to input average and current reference 1 adjust, form current reference 2.Wherein current reference 1 can be fixed value, can be also the reference value that DC converting unit output feedback is exported through low-pass filter unit.Too short when the electronic transformer output that normally vibrates, when power output is not enough, corresponding DC converting unit input mean value declines, and signal processing unit improves current reference value 2, impels electronic transformer to expand normal vibration output; Otherwise when input mean value is too high, signal processing unit reduces current reference value 2, make electronic transformer shorten normal vibration output.Low-pass filter unit guarantees that the reference signal of exporting to electric current loop remains unchanged in power frequency period, thereby makes the stable output of electronic transformer
Please refer to shown in Figure 12, the voltage of the DC converting unit of feed-in low-pass filter unit is also the input current of DC converting unit.The output voltage of electronic transformer is the input voltage V2 of LED driver after rectifier bridge.Sampling input voltage V2, directly acts on the work of electric current loop, thereby according to the variation of input, changes switching frequency or the duty ratio of DC converting unit, reaches the object of controlling output.Input voltage V2, after feedback, enters low-pass filter unit, and low-pass filtering electric unit bandwidth is less than 100Hz, and representative value is about 10 ~ 20Hz, and therefore, the output of low-pass filter unit can be equivalent to the mean value (input mean value) of input voltage V2.Signal processing unit connects DC converting unit, and the current peak signal of sampling DC converting unit forms sampled signal.Signal processing unit first will input mean value and sample rate current is added formation superposed signal.Superposed signal and current reference compare, and when input mean value is on the low side, in the situation that current reference is constant, current feedback raises automatically, and this is equivalent to improve current reference; Otherwise when input mean value is higher, current feedback reduces, and is equivalent to reduce current reference.Low-pass filter unit guarantees that the reference signal of exporting to electric current loop remains unchanged in power frequency period, thereby makes the stable output of electronic transformer.
Above three execution modes are wherein three schemes of the present utility model that realize that exemplify.Because the utility model is applicable to the topology of various DC converting unit, thus feedback control loop, signal processing unit be provided with a lot of may.Core of the present utility model is to design as required different loops, then between feedback unit and signal processing unit, introduces low-pass filter unit.
Concrete, please refer to shown in Figure 13, the utility model the first preferred embodiment LED driver 10 comprises DC converting unit 11, controls driver element 12, connects and control the signal processing unit 13 of driver element 12 and the low-pass filter unit 14 that connects signal processing unit 13.Control driver element 12 and connect DC converting unit 11, control and drive DC converting unit 11.The voltage feed-in low-pass filter unit 14 of DC converting unit 11, the signal by low-pass filter unit 14 filtering, after signal processing unit 13, is controlled driver element 12.Signal processing unit 13 comprises comparator U2.The output of comparator U2 connects controls driver element 12, and comparator U2 controls the shutoff of driver element 12.LED driver 10 also comprises feed-in unit 15, and the first end of feed-in unit 15 connects DC converting unit 11, the second ends and connects low-pass filter unit 14.The first end of feed-in unit 15 connects the output terminals A of DC converting unit 11, and the output voltage V of DC converting unit 11 0 is fed back to low-pass filter unit 14.In the present embodiment, feed-in unit 15 comprises resistance R 1 and resistance R 2, and resistance R 1 is divider resistance, and resistance R 2 is sampling resistor.
The first end of low-pass filter unit 14 connects feed-in unit 15, and the second end of low-pass filter unit 14 connects the negative pole of the comparator U2 of signal processing unit 13.DC converting unit 11 comprises sampling resistor Rs, and the positive pole of the comparator U2 of signal processing unit 13 connects sampling resistor Rs, thereby by the positive pole of the peak current feed-in comparator U2 of DC converting unit 11.Low-pass filter unit 14 comprises operational amplifier U1 and capacitor C 1, resistance R 3 series circuits, one end concatenation operation amplifier U1 negative pole of capacitor C 1, resistance R 3 series circuits, the output of other end concatenation operation amplifier U1.The negative pole of the second end concatenation operation amplifier U1 of feed-in unit 15.
Control driver element 12 and comprise control unit 120, driver element 121 and clock signal transmitter unit 122.Signal processing unit 13 connection control units 120, control unit 120 connects driver element 121.In the present embodiment, control unit 120 is rest-set flip-flop.Clock signal transmitter unit 122 sends clock signal to control unit 120.
DC converting unit 11 booster circuits, voltage V1 and electric current I 1 are from electronic transformer output, and diode D1, D2, D3, D4 form rectifier bridge, owing to being low pressure applications, generally use Schottky diode to realize high speed operation and low-power consumption.Inductance L, switch element Q and diode D5 are respectively boost inductance, switching tube and output diode, and capacitor C is output filter capacitor, and sampling resistor Rs is for detection of inductive current peak.Driver element 121 connecting valve element Q are with the turn-on and turn-off of control switch element Q.Due to when the switch element Q conducting, inductive current directly flows through switch element Q place branch road, therefore can be sampling resistor Rs string below switch element Q.When switch element Q conducting, input voltage V2 is added in inductance L, makes inductive current increase, and when switch element Q disconnects, the difference of output voltage V o and input voltage V2 is oppositely superimposed upon in inductance L, and inductive current is declined.Output voltage carries out dividing potential drop feedback through resistance R 1 and R2, be connected to the negative pole of operational amplifier U1, the positive pole of operational amplifier U1 is fiducial reference source, the COMPENSATION NETWORK DESIGN of operational amplifier U1 realizes by resistance R 3 and capacitor C 1, resistance R 3 and capacitor C 1 can be limited in loop bandwidth in 100Hz, and operational amplifier U1 becomes a low pass filter.Through the level and smooth current peak reference signal of signal formation of low-pass filter unit 14, be connected to the negative pole of comparator U2, the positive pole of comparator U2 is that inductive current peak detects, when actual inductive current peak value surpasses the reference signal value that low-pass filter unit 14 provides, comparator U2 upset, rest-set flip-flop output low level, by driver element 121 stopcock element Q.The conducting of switch element Q is that the clock signal of being sent by clock signal transmitter unit triggers.Clock signal triggers rest-set flip-flop output high level and makes switch element Q conducting by driving.
Concrete, please refer to shown in Figure 14, the utility model the second preferred embodiment LED driver 20 comprises DC converting unit 21, controls driver element 22, connects and control the signal processing unit 23 of driver element 22 and the low-pass filter unit 24 that connects signal processing unit 23.Control driver element 22 and connect DC converting unit 21, control and drive DC converting unit 21.The voltage feed-in low-pass filter unit 24 of DC converting unit 21, the signal by low-pass filter unit 24 filtering, after signal processing unit 23, is controlled driver element 22.Signal processing unit 23 comprises comparator U2.The output of comparator U2 connects controls driver element 22, and comparator U2 controls the shutoff of driver element 22.LED driver 20 also comprises feed-in unit 25, and the first end of feed-in unit 25 connects DC converting unit 21, the second ends and connects low-pass filter unit 24.The first end of feed-in unit 25 connects the input B of LED driver 20, and the input voltage V2 of LED driver 20 is fed back to low-pass filter unit 24.In the present embodiment, feed-in unit 25 comprises resistance R 1 and resistance R 2.
The first end of low-pass filter unit 24 connects feed-in unit 25, and the second end of low-pass filter unit 24 connects the negative pole of the comparator U2 of signal processing unit 23.DC converting unit 21 comprises sampling resistor Rs, and signal processing unit 23 also comprises signal superpositing unit 231.Signal superpositing unit 231 one end connect sampling resistor Rs, and the other end connects between low-pass filter unit 24 and comparator U2.Low-pass filter unit 24 comprises capacitor C 1, resistance R 1, R2, and capacitor C 1 is in parallel with resistance R 2, and resistance R 1 is connected in series with the parallel circuits of capacitor C 1, resistance R 2.Resistance R 1, R2 both, as the divider resistance of feed-in unit 25, formed again low-pass filter unit 24 together with capacitor C 1.Signal processing unit 23 connects the first end of low-pass filter unit 24.The positive pole of the signal of signal superpositing unit 231 and low-pass filter unit 24 feed-in comparator U2 after stack, signal processing unit 231 has reference source, and the negative pole of comparator U2 connects reference source.
Control driver element 22 and comprise control unit 220, driver element 221 and clock signal transmitter unit 222.Signal processing unit 23 connection control units 220, control unit 220 connects driver element 221.In the present embodiment, control unit 220 is rest-set flip-flop.Clock signal transmitter unit 222 sends clock signal to control unit 220.
DC converting unit 21 booster circuits, voltage V1 and electric current I 1 are from electronic transformer output, and diode D1, D2, D3, D4 form rectifier bridge, owing to being low pressure applications, generally use Schottky diode to realize high speed operation and low-power consumption.Inductance L, switch element Q and diode D5 are respectively boost inductance, switching tube and output diode, and capacitor C is output filter capacitor, and sampling resistor Rs is for detection of inductive current peak.Driver element 221 connecting valve element Q are with the turn-on and turn-off of control switch element Q.Due to when the switch element Q conducting, inductive current directly flows through switch element Q place branch road, therefore can be sampling resistor Rs string below switch element Q.When switch element Q conducting, input voltage V2 is added in inductance L, makes inductive current increase, and when switch element Q disconnects, the difference of output voltage V o and input voltage V2 is oppositely superimposed upon in inductance L, and inductive current is declined.Input voltage signal carries out dividing potential drop by resistance R 1 and R2, capacitor C 1 and resistance R 1, R2 form low-pass filter circuit, bandwidth frequency is controlled in 100Hz, high frequency and twice power frequency composition in order to filtering input voltage signal the inside, at capacitor C 1 two ends, obtain highly stable voltage like this, this voltage process resistance R 4 and R3 and inductive current peak sampling superpose, feed back to the positive pole of comparator U2, the negative pole of comparator U2 is fixing reference source, can set according to real output.When the normal oscillating part of input voltage V2 is not enough, capacitor C 1 low voltage obtained above, in order to make comparator U2 upset, inductive current peak needs further to rise, and it is large that input current I2 peak value becomes, and expands the normal oscillating part of V2.

Claims (13)

1. the LED driver for being connected with electronic transformer, comprises
Rectifier bridge, its input connects with described electronic transformer;
DC converting unit, its one end is connected with described rectifier bridge, and the other end is connected to give described LED load supplying with LED load;
Feed-in unit, is connected with described DC converting unit;
Low-pass filter unit, is connected with described feed-in unit;
Signal processing unit, is connected with described low-pass filter unit;
Control driver element, one end is connected with signal processing unit, and the other end is connected with described DC converting unit;
Described control driver element is controlled described DC converting unit according to described feed-in unit collection and through the feedback signal that described low-pass filter unit and signal processing unit pass over.
2. LED driver as claimed in claim 1, is characterized in that: by the signal of exporting after described low-pass filter unit filtering, be low ripple direct current signal.
3. LED driver as claimed in claim 1, is characterized in that: input voltage, output current or output voltage that the voltage of the DC converting unit of described feed-in low-pass filter unit is described LED driver.
4. LED driver as claimed in claim 1, is characterized in that: described signal processing unit comprises comparator, and the output of described comparator connects described control driver element, and described comparator is controlled the shutoff of described control driver element.
5. LED driver as claimed in claim 4, is characterized in that: described LED driver also comprises feed-in unit, and the first end of described feed-in unit connects described DC converting unit, and the second end connects described low-pass filter unit.
6. LED driver as claimed in claim 5, is characterized in that: the first end of described feed-in unit connects the output of described DC converting unit, and the output voltage of described DC converting unit is fed back to described low-pass filter unit.
7. LED driver as claimed in claim 6, is characterized in that: the first end of described low-pass filter unit connects described feed-in unit, and the second end of described low-pass filter unit connects the negative pole of the comparator of described signal processing unit.
8. LED driver as claimed in claim 7, it is characterized in that: described DC converting unit comprises sampling resistor, the positive pole of the comparator of described signal processing unit connects described sampling resistor, thereby by the positive pole of comparator described in the peak current feed-in of described DC converting unit.
9. LED driver as claimed in claim 5, is characterized in that: the first end of described feed-in unit connects the input of described DC converting unit, and the input voltage of described LED driver is fed back to described low-pass filter unit.
10. LED driver as claimed in claim 9, it is characterized in that: described DC converting unit comprises sampling resistor, described signal processing unit also comprises signal superpositing unit, described signal superpositing unit one end connects described sampling resistor, and the other end connects between described low-pass filter unit and described comparator.
11. LED drivers as claimed in claim 10, it is characterized in that: the signal of described signal superpositing unit and described low-pass filter unit input of comparator described in feed-in after stack, described signal processing unit has reference source, and the negative pole of described comparator connects described reference source.
12. LED drivers as claimed in claim 1, is characterized in that: described control driver element comprises control unit, driver element and clock signal transmitter unit, and described clock signal transmitter unit triggers described control unit.
13. LED drivers as claimed in claim 12, is characterized in that: described DC converting unit comprises switch element, and described control driver element is controlled work or the shutoff of described switch element.
CN201320577735.1U 2013-09-17 2013-09-17 LED drive Withdrawn - After Issue CN203504822U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104470039A (en) * 2013-09-17 2015-03-25 欧普照明股份有限公司 LED driver

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104470039A (en) * 2013-09-17 2015-03-25 欧普照明股份有限公司 LED driver

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