CN103249215B - LED driver system with dimmer detection - Google Patents
LED driver system with dimmer detection Download PDFInfo
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- CN103249215B CN103249215B CN201210370108.0A CN201210370108A CN103249215B CN 103249215 B CN103249215 B CN 103249215B CN 201210370108 A CN201210370108 A CN 201210370108A CN 103249215 B CN103249215 B CN 103249215B
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Abstract
An LED driver system includes an input for receiving a rectified AC conductive angle modulated voltage on a rectified node, a converter, a low-pass filter, and AC detector, and a driver network. The converter is coupled to the rectified node and includes a power switching device coupled to a switching node, in which the power switching device is controlled to convert the rectified AC conductive angle modulated voltage into an output voltage and an output current. The low-pass filter is configured to filter voltage of the switching node to provide a filtered voltage. The AC detector receives the filtered voltage and provides a current sense signal indicative thereof. The driver network controls duty cycle of the power switching device based on the current sense signal.
Description
The cross reference of related application
This application claims the rights and interests of the U.S. Provisional Application S/N 61/598,281 that on February 13rd, 2012 submits to, for all intentions and object, the full text of this application is incorporated herein by reference.
Accompanying drawing is sketched
By description subsequently and accompanying drawing, benefit of the present invention, feature and advantage will become and should be readily appreciated that, wherein:
Fig. 1 is the schematic block diagram of the conventional LED driver with light modulator detection for providing current to LED;
Fig. 2 is the sequential chart of the signal curve of the conventional LED driver relative time depicting Fig. 1, illustrates its work;
Fig. 3 is the schematic block diagram of the LED driver with light modulator detection according to an embodiment realization, this LED driver is used for providing current to LED, the parasitic noise causing flicker can not be introduced simultaneously, power factor or gross efficiency can not be reduced, and can not harmonic distortion be increased;
Fig. 4 is the sequential chart of the signal curve of the LED driver relative time depicting Fig. 3, illustrates its work;
Fig. 5 is the schematic block diagram of LED driver detected with light modulator realized according to another embodiment, this LED driver is used for providing current to LED, the parasitic noise causing flicker can not be introduced simultaneously, power factor or gross efficiency can not be reduced, and can not harmonic distortion be increased;
Fig. 6 is the schematic block diagram of the dimmer circuit realized according to another embodiment, this dimmer circuit is used for providing current to LED, the parasitic noise causing flicker can not be introduced simultaneously, power factor or gross efficiency can not be reduced, and can not harmonic distortion be increased; And
Fig. 7-9 shows the various different electronic equipment using converter, and this converter realizes according to any one structure described here, describes alternative type Use.
Describe in detail
By description subsequently and accompanying drawing, benefit of the present invention, feature and advantage will become and should be readily appreciated that.The following description presented is to manufacture and use the present invention when enabling those skilled in the art in the context that the present invention is provided at specific application and its demand.But, the various different amendment of preferred embodiment be it will be apparent to those of skill in the art, and other embodiment can be applied in the universal principle of this definition.Therefore, the present invention is not intended to be limited to particular implementation shown and described herein, but the most wide region consistent with principle disclosed herein and new feature is consistent.
Light emitting diode (LED) illumination is just becoming more and more universal.In order to use LED (comprising one or more LED element) to substitute incandescent lamp bulb, LED should with the traditional wire light modulator collaborative work for brilliance control.The similar circuit of some part that typical line dimmer uses TRIAC circuit or intercepts AC line voltage realizes.In order to control the brightness of LED, the angle of flow of LED driver monitoring cable light modulator, and this information is converted to current reference signal, for regulating the electric current through LED.
Fig. 1 is the schematic block diagram of the conventional LED driver system 100 detected with light modulator of LED " lamp " 108 for providing current to the independent LED element comprising one or more series coupled.In this case, adjustable line dimmer 102 receives input AC line voltage VAC, then provides AC angle of flow modulation voltage or " through copped wave " differential voltage VIN, this differential voltage VIN to be provided to a pair input of full wave bridge rectifier 104.Rectifier 104 has pair of output, and this provides through commutating voltage VREC on node 106 common node of lead-out terminal relative to the input of converter 101.This common node is illustrated as ground connection (GND), and it can be positive and negative or ground voltage level arbitrarily.
In the illustrated embodiment, converter 101 is configured to buck converter, and the VREC with higher voltage level is converted to the VOUT with lower voltage level by it.Converter 101 comprises the input filter capacitor C1 be coupling between node 106 and GND.Node 106 be coupled to further diode D1 negative electrode, be coupled to one end of output capacitor CO and be coupled to one end of LED 108.The other end of LED 108 is coupled to node 110, and node 110 is coupled to the other end of CO and one end of inductor L further.Output voltage VO UT produces across LED 108.The other end of inductor L is coupled to node 112, and node 112 is coupled to the anode of diode D1 further and is coupled to the drain electrode of Power switching devices Q.The source-coupled of Q is to GND, and its grid receives grid control signal G from LED driver 114.The voltage of VREC compares with fixed threshold voltage VTH by AC detector 116, thus generation current sensing signal IREF, this current sensing signal IREF is provided to the input of LED driver 114.
Power switching devices Q is illustrated as metal oxide semiconductor field effect tube (MOSFET), but also can use similar form (such as, FET, MOS device etc.), maybe can use the transistor of other type, such as bipolar junction transistor (BJTs) and analog, igbt (IGBTs) and analog etc.VAC can have about 180-200 volt (V) or similar peak amplitude.
Fig. 2 is the sequential chart of the curve drawing out VAC, VIN, VREC and IREF relative time, illustrates the work of conventional LED driver system 100.In one embodiment, line dimmer 102 is adjustable, thus for each half period (namely 180 degree), phase angle selected between 0 and 180 degree prune in the forward position of VAC and rear edge one or both, to provide VIN as AC angle of flow modulation voltage.In one embodiment, line dimmer 102 uses TRIAC or analog to postpone VAC waveform, until the predetermined phase angle selected according to the adjustment of light modulator at zero crossings.The dimmer phase angle degree selected is larger, and VIN is just pruned more or vanishing, to reduce the voltage of VIN.Once reach for each half period phase angle, VIN is just increased to line voltage (such as, TRIAC conducts), and the remainder of VAC exports converter 101 to, until the next half period.
VIN is to provide VREC in rectifier 104 rectification, and wherein the negative drift of VIN is converted to the just drift of VREC.VTH is the predetermined or fixing D/C voltage about VREC.In one embodiment, VTH has the voltage level of about 2% of VREC, such as about 1 to 4V.When VREC is lower than VTH, AC detector 116 asserts that IREF is low, and when VREC rises higher than VTH, asserts that IREF is high.Therefore, IREF produces the edge corresponding to VREF and VTH and intersect.Ideally, IREF produces ON time T
oN, this T
oNwhen VREC rises higher than VTH, and terminate lower than during VTH when VREC drops to, wherein IREF should be low, with T for the remaining part in each VREC cycle
aCillustrate.
In desirable structure, converter 101 is with electric current driving LED lamp 108, and the dutycycle (D) of this electric current and VREC is proportional, therefore proportional with the dutycycle of IREF, D=T herein
oN/ T
aC.Dutycycle is higher, and the electric current through LED 108 is larger, and therefore LED 108 is brighter.LED driver 114 detects the dutycycle of IREF, and produces the corresponding dutycycle of gate drive signal G, to drive Q generation through the electric current of LED 108.LED driver 114 with select switching frequency FSW and with the dutycycle based on IREF, Q is switched back and forth between Kai Heguan, to regulate the brightness of LED 108.FSW can be frequency level suitable arbitrarily, such as tens of or hundreds of KHz (KHz).
Ideally, line dimmer 102 not conducting completely during the chop section of VAC, thus VIN is zero; In other cases, line dimmer 102 is with very little impedance conducting, thus in remaining time for each cycle, VIN follows VAC.But the line dimmer of much reality strictly can not keep voltage in its cut-off state, which results in the noise distortion of VIN.During VREC expects to be the chop section of the VIN of zero, the distortion of VIN is reflected as the corresponding distortion of VREC.This distortion and then cause non-zero noise again on VREC, wherein VREC may rise higher than VTH during the barrier portion in this cycle.These distortions may cause the undesired spurious pulse 202 of IREF, and this spurious pulse correspondingly causes the change of the switching of Q (based on mobile or ripply internal DC reference voltage), thus the flicker causing LED 108 to produce undesired human eye can to discover.
The amplitude that can increase VTH to reduce or to eliminate the spurious pulse 202 of IREF, to minimize or to eliminate flicker.But, increase VTH and reduce power factor and gross efficiency, also add the harmonic distortion of LED current.It is desirable that, eliminate less desirable flicker, and do not introduce any one in these additional undesirably consequences.
Fig. 3 is the schematic block diagram of the LED driver system 300 with light modulator detection according to an embodiment realization, this LED driver system is used for providing current to LED, the parasitic noise causing flicker can not be introduced simultaneously, power factor or gross efficiency can not be reduced, and can not harmonic distortion be increased.The assembly similar with the assembly of conventional LED driver system 100 has identical drawing reference numeral.Line dimmer 102 and rectifier 104 provide VREC in a similar fashion on node 106, and assembly CI, D1, CO, L and Q are coupled in the similar mode of step-down controller 301.But AC detector 116 is replaced by low pass filter 302 and AC detector 316, and wherein low pass filter 302 connects VDS voltage but not VREC.In this embodiment, low pass filter 302 comprises resistance R1 and R2 and capacitor C1.R1 has coupled one end to node 112, and this node 112 produces VDS, and the other end of R1 is coupled to one end of R2, is coupled to one end of C1 and is coupled to the input of AC detector 316.The other end of R2 and C1 is coupled to GND.The common node of R1, R2 and C1 produces VDS signal VDSF after filtering, and this signal VDSF is provided to AC detector 316.VDSF and VTH compares by AC detector 316, for produce IREF signal with previously described similar mode.But because the version after filtering of VDS monitored by AC detector 316, parasitic noise as being eliminated at this with further describing.
Fig. 4 is the sequential chart of the curve depicting VAC, VIN, VREC, VDS, VDSF and IREF relative time, illustrates the work of LED driver system 300.VAC, VIN draw with substantially identical waveform construction with VREC, and wherein VIN and VREC comprises distortion, and these distortions are caused by the line dimmer 102 among other circuit unit.The voltage level of VTH is drawn together with VDS.As before, these distortions cause VREC to rise to higher than VTH, and this can cause the spurious pulse of IREF in conventional construction.But notice, the noise pulse on VREC can not rise to the level of VOUT, depends on specific structure, this level can be some tens of volts (such as, 30V).
At work, when the voltage level of VREC lower than VOUT, when namely convenient Q is for cut-off, the intrinsic body diodes of Q can conducting.VDS remains on about 0V, allows the error of diode drop, and can not rise to the level of VTH or VOUT.The voltage level of about VREC is risen to higher than VOUT, VDS when VREC rises.Raise in VTH through the relatively very fast ground of voltage VDSF of low pass filter 302, and AC detector 316 asserts that IREF is high.LED driver 114 continues the operation switching Q with FSW back and forth, and wherein the voltage of VDS correspondingly switches back and forth, and this uses diagonal to illustrate.Low pass filter 302 leaches the higher carrier frequencies of the work of VDS, thus when VREC is higher than VOUT, VDSF provides the envelope information of VDS.
When VREC reduces lower than VOUT, VDS vanishing.Based on the time constant of R1 and R2 of C1 and parallel combination, VDSF decays to zero, and decays soon lower than VTH thereafter.When VDSF reduces lower than VTH, it is low that AC detector 316 asserts that IREF gets back to, and VDSF is reduced to about zero.VDS remains on about zero and remains on about zero lower than VOUT, VDSF and lower than VTH.Therefore, during the remaining part in this cycle, IREF keeps low.By this way, although VREC has noise pulse, the spurious pulse on IREF is eliminated.
Fig. 5 is the schematic block diagram of LED driver system 500 detected with light modulator realized according to another embodiment, this LED driver system is used for providing current to LED 108, the parasitic noise causing flicker can not be introduced simultaneously, power factor or gross efficiency can not be reduced, and can not harmonic distortion be increased.The assembly similar with the assembly of LED driver system 300 has identical drawing reference numeral.Line dimmer 102 and rectifier 104 provide VREC in a similar fashion on node 106, and assembly CI, D 1, CO and Q are coupled in the similar mode of another step-down controller 501.In this case, inductor L is replaced by transformer T, and this transformer T has the armature winding be coupling between node 110 and 112, and a little end of this armature winding is coupled to node 110.Transformer T has secondary windings 502, and the nothing point end of this secondary windings 502 is coupled to GND, and it holds a little the anode being coupled to diode D2.The negative electrode of D2 is coupled to one end of R1, and wherein R2, C1 and AC detector 316 is coupled to the other end of R1 in a similar fashion.AC detector 316 provides IREF to LED driver 114 in a similar fashion, this generates G, and G drives Q with the similar fashion described before with corresponding dutycycle.
Work substantially similar with LED driver system 300.When VREC is lower than VOUT, when namely convenient Q switches, VDS is zero, and through the electric current vanishing of the armature winding of transformer T or close to zero.Secondary windings produces no-voltage or does not produce voltage, thus pulls VDSF to zero.When VREC rises higher than VOUT, the electric current be flowing in the armature winding of transformer T caused by switching causes and form corresponding voltage in secondary windings 502, and this voltage causes VDSF correspondingly to rise, and AC detector 316 asserts that IREF is high.When VREC reduces lower than VOUT, VDS vanishing, and through the electric current vanishing of transformer T, thus according to the time constant of RC, VDSF is reduced to zero.IREF is withdrawn into low when VDSF reduces lower than VTH, AC detector 316.
Fig. 6 is the schematic block diagram of LED driver system 600 detected with light modulator realized according to another embodiment, this LED drive system is used for providing current to LED 108, the parasitic noise causing flicker can not be introduced simultaneously, power factor or gross efficiency can not be reduced, and can not harmonic distortion be increased.LED driver system 600 constructs in the mode substantially similar with LED driver system 500 and works.Unique difference is the polarity of the secondary windings of the transformer T of converter 601, and shown by secondary windings 602, secondary windings 602 is contrary compared with secondary windings 502.Work substantially similar.
The potential advantage of LED driver system 500 and 600 is, transformer T allows the voltage level of VDSF less significantly, and VTH correspondingly reduces in proportion.
Fig. 7-9 shows the various different electronic equipment using converter 700, and this converter 700 realizes, such as converter 301,501 or 601 according to any one structure described herein, describes alternative type Use.As shown in Figure 7, converter 700 receives VREC, and drives the DC load 702 of any type.As shown in Figure 8, converter 700 receives VREC, charges to battery or the battery pack 802 that comprises one or more rechargeable battery.As shown in Figure 9, converter 700 receives VREC, and provides current to coil 902 or analog, to produce the magnetic field for motor 904 or analog.
Although describe the present invention with reference to preferred versions more of the present invention with considerable details, other version and change are possible with expected.Those skilled in the art should recognize, they can easily use concept disclosed herein and concrete embodiment as design or the basis of revising other structure, these other structures for providing the object identical with the present invention, and do not deviate from the spirit and scope of the present invention be defined by the following claims.
Claims (19)
1. a LED driver system, comprising:
Input, receives the AC angle of flow modulation voltage through rectification at rectification node;
Converter, be coupled to described rectification node, and comprising the power switching device being coupled to switching node, wherein said power switching device is controlled between the AC angle of flow modulation voltage of rectification, switch the voltage of described switching node at low voltage level back and forth to described and the described AC angle of flow modulation voltage through rectification is converted to output voltage and output current;
Low pass filter, is configured to the described voltage filter to described switching node, to provide through filtering voltage, and the described dutycycle through filtering voltage with the angle of flow indicating the described AC angle of flow modulation voltage through rectification;
AC detector, its reception is described through filtering voltage, and provides the current sensing signal indicating the described described dutycycle through filtering voltage; And
Drive network, it controls described power switching device based on described current sensing signal.
2. LED driver system as claimed in claim 1, it is characterized in that, described converter, based on the described described dutycycle through filtering voltage, switches described power switching device back and forth with a dutycycle.
3. LED driver system as claimed in claim 1, it is characterized in that, described power switching device comprises MOSFET.
4. LED driver system as claimed in claim 1, it is characterized in that, described converter comprises:
MOSFET, is configured to described power switching device, has the drain electrode being coupled to described switching node and the source electrode being coupled to reference mode;
Input capacitor, is coupling between described rectifier node and described reference mode;
First diode, has the anode being coupled to described switching node and the negative electrode being coupled to described rectifier node;
Output capacitor, has the first end being coupled to described rectifier node and the second end being coupled to output node; And
Inductor, is coupling between described output node and described switching node.
5. LED driver system as claimed in claim 4, it is characterized in that, described inductor comprises the armature winding of transformer, and described transformer comprises secondary windings further, and wherein said low pass filter is by the second diode-coupled extremely described secondary windings.
6. LED driver system as claimed in claim 1, it is characterized in that, described low pass filter comprises resistor-capacitor filter.
7. LED driver system as claimed in claim 1, it is characterized in that, described low pass filter comprises resistor-capacitor filter, is configured to the envelope information of the voltage providing described switching node.
8. LED driver system as claimed in claim 1, is characterized in that, comprise further:
Light modulator, receives AC voltage and provides AC angle of flow modulation voltage; And
Full wave bridge rectifier, has the input that receives described AC angle of flow modulation voltage and has the output being coupled to described rectification node, for providing the described AC angle of flow modulation voltage through rectification.
9. an electronic installation, comprising:
Light modulator, receives AC voltage and provides AC angle of flow modulation voltage; And
Full wave bridge rectifier, has the input and the output with the AC angle of flow modulation voltage provided through rectification that receive described AC angle of flow modulation voltage; And
Converter, comprising:
Rectification node, receives the described AC angle of flow modulation voltage through rectification;
Power switching device, be coupled to switching node, wherein said power switching device is controlled between the AC angle of flow modulation voltage of rectification, switch the voltage of described switching node at low voltage level back and forth to described and be converted to across the output voltage of a pair output node and the electric current through described a pair output node by the described AC angle of flow modulation voltage through rectification;
Low pass filter, is configured to the described voltage filter to described switching node, to provide through filtering voltage, and the described dutycycle through filtering voltage with the angle of flow indicating the described AC angle of flow modulation voltage through rectification;
AC detector, it receives and describedly provides through filtering voltage the current sensing signal indicating the described described dutycycle through filtering voltage; And
Drive networks, it controls described power switching device based on described current sensing signal.
10. electronic installation as claimed in claim 9, is characterized in that, comprise the DC load being coupled to described a pair output node further.
11. electronic installations as claimed in claim 10, it is characterized in that, described DC load comprises at least one LED.
12. electronic installations as claimed in claim 10, it is characterized in that, described DC load comprises battery charger.
13. electronic installations as claimed in claim 10, it is characterized in that, described DC load comprises synchronous motor.
14. electronic installations as claimed in claim 10, it is characterized in that, described converter comprises:
MOSFET, is configured to described power switching device, has the drain electrode being coupled to described switching node and the source electrode being coupled to reference mode;
Input capacitor, is coupling between described rectifier node and described reference mode;
First diode, has the anode being coupled to described switching node and the negative electrode being coupled to described rectifier node;
Output capacitor, has the first end being coupled to described rectifier node and the second end being coupled to output node; And
Inductor, is coupling between described output node and described switching node.
15. as the electronic installation of claim 14, and it is characterized in that, described inductor comprises the armature winding of transformer, and described transformer comprises secondary windings further, and wherein said low pass filter by the second diode-coupled to described secondary windings.
16. electronic installations as claimed in claim 10, it is characterized in that, described low pass filter comprises resistor-capacitor filter.
17. electronic installations as claimed in claim 10, it is characterized in that, described low pass filter comprises resistor-capacitor filter, is configured to the envelope information of the described voltage providing described switching node.
18. 1 kinds of methods detecting the light modulation angle of LED driver, described LED driver receives the AC angle of flow modulation voltage through rectification, and control switching device shifter the described AC angle of flow modulation voltage through rectification to be converted to the electric current by LED, described method comprises:
Sense across the voltage of described switching device shifter, and provide the envelope information comprising institute's sensing voltage through filtering voltage, the angle of flow of the described AC angle of flow modulation voltage through rectification of wherein said envelope information instruction;
Compare described with predetermined threshold through filtering voltage information, to provide the current sensing signal indicating the described angle of flow; And
Use described current sensing signal to control the switching of described switching device shifter.
19. methods as claimed in claim 18, is characterized in that, comprise further and control described LED driver, described LED driver switches described switching device shifter based on described current sensing signal back and forth in a dutycycle.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201261598281P | 2012-02-13 | 2012-02-13 | |
| US61/598,281 | 2012-02-13 | ||
| US13/536,892 US8901832B2 (en) | 2012-02-13 | 2012-06-28 | LED driver system with dimmer detection |
| US13/536,892 | 2012-06-28 |
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| Publication Number | Publication Date |
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| CN103249215A CN103249215A (en) | 2013-08-14 |
| CN103249215B true CN103249215B (en) | 2015-04-29 |
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| CN201210370108.0A Active CN103249215B (en) | 2012-02-13 | 2012-09-27 | LED driver system with dimmer detection |
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| KR102257718B1 (en) * | 2014-10-01 | 2021-05-28 | 매그나칩 반도체 유한회사 | Circuit driving light emitting diode and light apparatus comprising the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101990344A (en) * | 2009-08-03 | 2011-03-23 | 英特赛尔美国股份有限公司 | Inrush current limiter for an LED driver |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100555825C (en) * | 2007-01-11 | 2009-10-28 | 鸿富锦精密工业（深圳）有限公司 | Electrode converting circuit |
| US8390214B2 (en) * | 2009-08-19 | 2013-03-05 | Albeo Technologies, Inc. | LED-based lighting power supplies with power factor correction and dimming control |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101990344A (en) * | 2009-08-03 | 2011-03-23 | 英特赛尔美国股份有限公司 | Inrush current limiter for an LED driver |
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