CN205546102U - Light -emitting diode (LED) driving circuit - Google Patents
Light -emitting diode (LED) driving circuit Download PDFInfo
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- CN205546102U CN205546102U CN201620352774.5U CN201620352774U CN205546102U CN 205546102 U CN205546102 U CN 205546102U CN 201620352774 U CN201620352774 U CN 201620352774U CN 205546102 U CN205546102 U CN 205546102U
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Abstract
The utility model provides a light -emitting diode (LED) driving circuit is through the non - isolation DCDC converting unit and the load of stationary flow unit common drive LED of output series connection, by the sampled signal VS of electrical appliance industry the control unit according to the non - isolation DCDC converting unit output voltage V2 of sign, the feedback signal VFB relevant with the output ripple of this stationary flow unit and with the direct current base mark signal vref of this output ripple's big or small positive correlation, the output voltage ripple of controlling non - isolation DCDC converting unit is opposite with the phase place of the output voltage ripple of stationary flow unit, and the output voltage average value that makes non - isolation DCDC converting unit is followed the output ripple's of stationary flow unit size and is changed, and then make the ripple in the LED load reduce elimination even, avoid output current to have great ripple and cause the LED lamp stroboscopic phenomenon to appear, and guarantee that the circuit is stable and efficiency is optimum.
Description
Technical field
This utility model relates to LED actuation techniques field, particularly relates to a kind of LED drive circuit.
Background technology
LED, as a kind of novel illumination device, owing to its luminous efficiency is high, is widely used in illumination neck
Territory, and it typically requires constant-current driving, the LED driver driven as its current stabilization in the prior art is
Realize characteristic with low cost and simple in construction, frequently with single-stage solution.
And use the LED driver of single-stage solution, owing to PFC (Power Factor taken into account by needs
Correction, PFC) function, i.e. it controls loop needs the slowest response speed just can have
Higher PF (Power Factor, power factor) value, therefore, it is relatively slow that it controls loop response speed,
And this can cause output electric current to have bigger ripple, the cycle of this ripple is the input ac voltage cycle
Half.When LED driver connects load, this current ripples will cause LED stroboscopic phenomenon occur,
This stroboscopic phenomenon will affect the service life of LED, also have certain damage to human eye.
Utility model content
In view of this, this utility model provides a kind of LED drive circuit, to solve prior art output
The problem that electric current has bigger ripple and causes LED stroboscopic phenomenon occur.
To achieve these goals, the technical scheme that this utility model embodiment provides is as follows:
A kind of LED drive circuit, including:
Control the steady flow unit of the stable current value of described LED drive circuit output；
It is provided commonly for driving the non-isolation DC/DC converter unit of LED load, institute with described steady flow unit
The outfan of the outfan and described non-isolation DC/DC converter unit of stating steady flow unit is connected；
Obtain the output ripple of described steady flow unit, and generate and described output stricture of vagina according to described output ripple
The feedback signal acquiring unit of the feedback signal that ripple is relevant；Described output ripple includes: output current ripple
And/or described output voltage ripple；The input of described feedback signal acquiring unit and described steady flow unit
Outfan is connected；
The DC reference generating the positively related DC reference signal of size with described output ripple obtains single
Unit；
Obtain a sampled signal characterizing described non-isolation DC/DC converter unit output voltage, and receive
Described feedback signal and described DC reference signal, make described non-isolation DC/DC according to described feedback signal
The opposite in phase of the output voltage ripple of the output voltage ripple of converter unit and described steady flow unit, and root
The output voltage average value making described non-isolation DC/DC converter unit according to described DC reference signal follows institute
The Voltage loop control unit stating the size of output ripple and change；The outfan of described Voltage loop control unit
It is connected with the control end of described non-isolation DC/DC converter unit；Two of described Voltage loop control unit defeated
Enter end respectively with the outfan of described DC reference acquiring unit and the output of described feedback signal acquiring unit
End is connected.
Preferably, described feedback signal acquiring unit includes: block isolating circuit；The input of described block isolating circuit
End is connected with the outfan of described steady flow unit, and the outfan of described block isolating circuit controls with described Voltage loop
The input of unit is connected.
Preferably, described feedback signal acquiring unit includes:
Obtain the difference channel of the output parameter of described steady flow unit；Two inputs of described difference channel
It is connected with two outfans of described steady flow unit respectively；
The described feedback signal relevant to described steady flow unit output ripple is obtained according to described output parameter,
And described feedback signal is input to the block isolating circuit of described Voltage loop control unit；Described block isolating circuit
Input is connected with the outfan of described difference channel.
Preferably, described DC reference acquiring unit includes: obtaining feedback signal maximum is described direct current
The maximum value circuit of reference signal；The input of described maximum value circuit connects the output of described block isolating circuit
End, the outfan of described maximum value circuit is the outfan of described DC reference acquiring unit.
Preferably, described DC reference acquiring unit includes: make described DC reference signal vary with temperature
And the temperature sensing circuit of inverse change.
Preferably, described steady flow unit is isolated form topology, and described steady flow unit includes: primary side winding,
First vice-side winding, the first rectification module, the first resistance and the first switching tube；Wherein:
The outfan of described first vice-side winding is connected with the input of described first rectification module；
The outfan that outfan is described steady flow unit of described first rectification module；
Different name end is described steady flow unit input of described primary side winding；
The Same Name of Ends of described primary side winding passes sequentially through described first switching tube and described first resistance connects institute
State another input of steady flow unit；
The control end of described first switching tube receives and drives signal.
Preferably, described steady flow unit also includes: the second vice-side winding and the second rectification module；Described
The outfan of two vice-side winding is connected with the input of described second rectification module；Described second rectification module
Outfan be connected with the input of described non-isolation DC/DC converter unit.
Preferably, described Voltage loop control unit includes: adder and the first integrated transporting discharging；Described addition
One input of device receives described DC reference signal, and another input of described adder receives described
Feedback signal；The outfan of described adder is connected with an input of described first integrated transporting discharging；Institute
Another input stating the first integrated transporting discharging receives described sampled signal；
Or, described Voltage loop control unit includes: subtractor and the second integrated transporting discharging；Described subtractor
Input receive described feedback signal；Another input of described subtractor receives described sampling
Signal；The outfan of described subtractor is connected with an input of described second integrated transporting discharging；Described
Another input of two integrated transporting dischargings receives described DC reference signal；
Wherein, described feedback signal and described output ripple opposite in phase.
Preferably, described Voltage loop control unit includes: subtractor and the first integrated transporting discharging；Described subtraction
One input of device receives described DC reference signal, and another input of described subtractor receives described
Feedback signal；The outfan of described subtractor is connected with an input of described first integrated transporting discharging；Institute
Another input stating the first integrated transporting discharging receives described sampled signal；
Or, described Voltage loop control unit includes: adder and the second integrated transporting discharging；Described adder
Input receive described feedback signal；Another input of described adder receives described sampling
Signal；The outfan of described adder is connected with an input of described second integrated transporting discharging；Described
Another input of two integrated transporting dischargings receives described DC reference signal；
Wherein, described feedback signal is identical with described output ripple phase place.
Preferably, also include exporting dim signal extremely described steady flow unit, make the output of described steady flow unit
The dimming control unit that electric current changes.
The application provides a kind of LED drive circuit, controls described LED drive circuit by steady flow unit defeated
Go out stable current value；Non-isolation DC/DC the converter unit connected by outfan and described steady flow unit
Jointly drive LED load；The output ripple of described steady flow unit is obtained by feedback signal acquiring unit,
And feedback signal VFB of described output ripple is generated according to described output ripple；Then DC reference is passed through
Acquiring unit generates the size positively related DC reference signal Vref with described output ripple；Last by electricity
Pressure ring control unit obtains a sampling characterizing described non-isolation DC/DC converter unit output voltage V2
Signal VS, and receive feedback signal VFB and DC reference signal Vref, according to described sampled signal VS
Control the output voltage ripple of described non-isolation DC/DC converter unit and the output voltage of described steady flow unit
The opposite in phase of ripple, and make described non-isolation DC/DC converter unit according to DC reference signal Vref
Output voltage average value is followed the size of described output ripple and is changed, and makes described non-isolation DC/DC conversion
The output voltage ripple of unit offsets with the output voltage ripple of described steady flow unit, and then makes LED bear
Ripple reduction in load even eliminates, it is to avoid output electric current has bigger ripple and causes LED to occur
Stroboscopic phenomenon.
Accompanying drawing explanation
In order to be illustrated more clearly that this utility model embodiment or technical scheme of the prior art, below will
The accompanying drawing used required in embodiment or description of the prior art is briefly described, it should be apparent that,
Accompanying drawing in describing below is only embodiment of the present utility model, comes for those of ordinary skill in the art
Say, on the premise of not paying creative work, it is also possible to obtain other accompanying drawing according to the accompanying drawing provided.
The structural representation of a kind of LED drive circuit that Fig. 1 provides for the embodiment of the present application；
A kind of signal waveform schematic diagram that Fig. 2 provides for another embodiment of the application；
Another signal waveform schematic diagram that Fig. 3 provides for another embodiment of the application；
The structural representation of a kind of LED drive circuit that Fig. 4 provides for another embodiment of the application；
The structural representation of another LED drive circuit that Fig. 5 provides for another embodiment of the application.
Detailed description of the invention
Below in conjunction with the accompanying drawing in this utility model embodiment, to the technology in this utility model embodiment
Scheme is clearly and completely described, it is clear that described embodiment is only this utility model one
Divide embodiment rather than whole embodiments.Based on the embodiment in this utility model, this area is common
The every other embodiment that technical staff is obtained under not making creative work premise, broadly falls into this
The scope of utility model protection.
This utility model provides a kind of LED drive circuit, has relatively solving prior art output electric current
Big ripple and the problem that causes LED that stroboscopic phenomenon occurs.
Concrete, as it is shown in figure 1, described LED drive circuit includes: steady flow unit 101, non-isolated
DC/DC converter unit 102, feedback signal acquiring unit 103, DC reference acquiring unit 104 and voltage
Ring control unit 105；Wherein:
The outfan series connection of steady flow unit 101 and non-isolation DC/DC converter unit 102；
The input of feedback signal acquiring unit 103 is connected with the outfan of steady flow unit 101；
Two inputs of Voltage loop control unit 105 respectively with the output of feedback signal acquiring unit 103
The outfan of end and DC reference acquiring unit 104 is connected；The outfan of Voltage loop control unit 105 with
The control end of non-isolation DC/DC converter unit 102 is connected.
What deserves to be explained is, the anode of the outfan of steady flow unit 101 and the positive pole of LED load in Fig. 1
It is connected, the negative terminal of the outfan of non-isolation DC/DC converter unit 102 and the negative pole of described LED load
It is connected；In actual applications, it would however also be possible to employ the outfan of non-isolation DC/DC converter unit 102 is just
End is connected with the positive pole of LED load, the negative terminal of the outfan of steady flow unit 101 and described LED load
Negative pole is connected；Fig. 1 is only a kind of example, steady flow unit 101 and non-isolation DC/DC converter unit 102
With the connected mode of described LED load being not specifically limited, can be according to the applied environment of its reality
Fixed.
Concrete operation principle is:
Steady flow unit 101 controls the current value that the output of described LED drive circuit is stable；
Non-isolation DC/DC converter unit 102 and steady flow unit 101 drive LED load jointly；
Feedback signal acquiring unit 103 obtains the output ripple of steady flow unit 101, and according to described output
Ripple generates feedback signal VFB relevant to described output ripple；
Optionally, described output ripple includes: output current ripple and/or output voltage ripple.
DC reference acquiring unit 104 generates the size positively related DC reference letter with described output ripple
Number Vref；
Voltage loop control unit 105 obtains one and characterizes non-isolation DC/DC converter unit 102 output voltage
Sampled signal VS of V2, and receive feedback signal VFB and DC reference signal Vref, according to sampling letter
Number VS makes the output voltage ripple of non-isolation DC/DC converter unit 102 and the output of steady flow unit 101
The opposite in phase of voltage ripple, and make non-isolation DC/DC converter unit according to DC reference signal Vref
The output voltage average value of 102 is followed the size of the output ripple of steady flow unit 101 and is changed.
The described LED drive circuit that the application provides, by above-mentioned annexation and operation principle, controls
The output voltage ripple of non-isolation DC/DC converter unit 102 and the output voltage ripple of steady flow unit 101
Opposite in phase, and it is described defeated to make the output voltage average value of non-isolation DC/DC converter unit 102 follow
Go out the size of ripple and change, make output voltage ripple and the current stabilization of non-isolation DC/DC converter unit 102
The output voltage ripple of unit 101 offsets, and then makes the ripple reduction in LED load even eliminate,
Avoid exporting electric current to there is bigger ripple and cause LED that stroboscopic phenomenon occurs.
What deserves to be explained is, in prior art, cause in order to avoid output electric current has bigger ripple
The stroboscopic phenomenon that LED occurs, the LED driver of employing two-step scheme is also by more selection, thereafter
The input directly outfan with prime AC-DC converter of level DC-DC converter is connected, described before
Level AC-DC converter is used for realizing PFC function, and described rear class DC-DC converter is used for realizing constant current
Or pressure-keeping functions, the control loop response speed of prime AC-DC converter can be very slow, without causing
LED driver output current ripple problem, the control loop response speed of rear class DC-DC converter is permissible
Comparatively fast, meet quickly adjust and reduce output current ripple demand, it is easy to solution single-stage solution exist
Problem.
But two-step scheme not only structure is complicated, cost is high, and turns owing to input power has carried out secondary
Change, make the efficiency product that efficiency is two-stage circuit of LED driver.Such as front stage circuits efficiency is η 1,
Late-class circuit efficiency is η 2, then prior art use two-step scheme LED driver efficiency eta=η 1 ×
η 2, greatly reduces the efficiency of LED driver, increases loss, it is impossible to highlight LED illumination System
Energy-conservation advantage.
And use the described LED drive circuit that the present embodiment provides, by above-mentioned connected mode with control former
Reason, it is not necessary to the loop response speed accelerating main circuit realizes low ripple output, therefore can ensure that higher
PF value while, if the efficiency of steady flow unit 101 is η 1, non-isolation DC/DC converter unit 102
Efficiency be η 2, the efficiency eta of the most described LED drive circuit is only slightly less than η 1, described LED and drives electricity
The efficiency eta on the road degree less than η 1 depends on that non-isolation DC/DC converter unit 102 processes the big of power
Little, compared to existing technology in use the LED driver efficiency of two-step scheme high and be lost low.
In concrete actual application, the DC reference that the DC reference acquiring unit 104 in Fig. 1 generates
Signal Vref and the size positive correlation of described output ripple, specifically refer to, and DC reference signal Vref is with surely
Flow the ripple size variation of unit 101 output voltage V1 and change in the same direction, i.e. steady flow unit 101 exports electricity
The ripple of pressure V1 is the biggest, and DC reference signal Vref is the biggest.
The output voltage waveforms of described steady flow unit is as shown in the V1 in Fig. 2, and described feedback signal obtains single
Unit obtain V1 AC compounent obtain feedback signal VFB, described DC reference acquiring unit generate with
The size positively related DC reference signal Vref of described output ripple, described Voltage loop control unit obtains
One sampled signal VS characterizing non-isolation DC/DC converter unit output voltage V2, described Voltage loop control
Unit processed exports control signal according to VFB, Vref and VS, and described non-isolation DC/DC converter unit connects
By described control signal, make self output voltage V2 with the AC compounent reverse with the AC compounent of V1.
The output voltage Vled=V1+V2 of so obtained described LED drive circuit, its ripple will reduce.For
The ripple output voltage Vled of described LED drive circuit on is completely eliminated, the AC compounent of V2
Size should equal in magnitude with V1 AC compounent, in opposite direction.
Feedback signal acquiring unit 103 in Fig. 1 and the setting of DC reference acquiring unit 104, be for
The signal (Vref-VFB) that acquisition is reverse with the ripple of steady flow unit 101 output voltage V1, such as Fig. 2
Shown in；The valley of the peak value of steady flow unit 101 output voltage V1 corresponding (Vref-VFB)；And will
(Vref-VFB) as the comparison signal of sampled signal VS, Voltage loop control unit 105 is according to both
Comparative result output control signal VC, makes the output voltage of non-isolation DC/DC converter unit 102 with steady
Unit 101 output voltage V1 is equal in magnitude for stream, in opposite direction, eliminates the ripple in LED load with this.
Oscillogram as shown in Figure 3, in order to be completely eliminated the output voltage Vled of described LED drive circuit
Ripple, DC reference signal Vref should be greater than the half equal to V1 ripple peak-to-peak value, otherwise,
(Vref-VFB) will appear from continuous 0 value, the stricture of vagina on the output voltage Vled of described LED drive circuit
Ripple can not be completely eliminated；Further, the value of DC reference signal Vref followed by V1 ripple change and
Change, V1 ripple increases (V1 ' as shown in Figure 3), then Vref increases (as shown in Figure 3
Vref '), (Vref-VFB) also will increase, as shown in Figure 3 (Vref '-VFB ')；
Otherwise, V1 ripple reduces, and Vref reduces.
Because the energy (DC voltage) that LED load obtains from described non-isolation DC/DC converter unit
Have passed through described steady flow unit and described non-isolation DC/DC converter unit two-stage circuit, its efficiency is less than only
Through the efficiency of described steady flow unit, so arranging DC reference signal Vref along with described steady flow unit
The change of output voltage V1 ripple and change, can not only ensure to drop the effect of ripple, and circuit can be improved
Efficiency.So, most preferably, the DC reference signal Vref output electricity equal to described steady flow unit is set
The half of pressure V1 ripple peak-to-peak value, or stable for holding circuit, slightly larger than its half.The most do not do and have
Body limits, all in the protection domain of the application.
In another embodiment of this utility model, characterize described non-isolation DC/DC converter unit output electricity
Sampled signal VS of pressure V2 directly obtains from the outfan of described non-isolation DC/DC converter unit, as
Shown in Fig. 4.
Preferably, as shown in Figure 4, described steady flow unit is isolated form topology, and described steady flow unit includes:
Primary side winding, first vice-side winding the 401, first rectification module, the first resistance R1 and the first switching tube K1；
Wherein:
The outfan of the first vice-side winding 401 is connected with the input of described first rectification module；
The outfan that outfan is described steady flow unit of described first rectification module；
Different name end is described steady flow unit input of described primary side winding；
The Same Name of Ends of described primary side winding passes sequentially through the first switching tube K1 and the first resistance R1 and is connected to institute
State another input of steady flow unit；
The control end of the first switching tube K1 receives and drives signal；Described driving signal controls described steady flow unit
Realize stable electric current output.
Preferably, according to described driving signal, described steady flow unit primary current sampled signal controls described
The signal of steady flow unit current stabilization output.
Preferably, described primary current is obtained by the first resistance R1 sampling.
Preferably, as shown in Figure 4, described steady flow unit also includes: the second vice-side winding 402 and second
Rectification module；The outfan of the second vice-side winding 402 is connected with the input of described second rectification module；
The outfan of described second rectification module is connected with the input of described non-isolation DC/DC converter unit.
See Fig. 4, when described steady flow unit is isolated form topology, described non-isolation DC/DC converter unit
The transformator that input voltage vin is described steady flow unit the second vice-side winding 402 rectified after voltage.
Preferably, as shown in Figure 4, described feedback signal acquiring unit includes: block isolating circuit；Described every
The input of straight circuit connects the outfan of described steady flow unit, and the outfan of described block isolating circuit is with described
The input of Voltage loop control unit is connected.
Described steady flow unit shown in Fig. 4 and described feedback signal acquiring unit are only a kind of example, not
Necessarily it is defined in this, can be depending on the applied environment that it is concrete.
In another embodiment of the present utility model, as shown in Figure 4, described DC reference acquiring unit
Including: make DC reference signal Vref vary with temperature and the temperature sensing circuit of inverse change.
Owing to temperature is the lowest, the output electrolysis of described steady flow unit and shown non-isolation DC/DC converter unit
Electric capacity ESR increases, and ripple increases.The most described DC reference acquiring unit includes described temperature detection electricity
Road, can make the DC reference signal Vref being input to described Voltage loop control unit along with variations in temperature
Change, temperature raises, and DC reference signal Vref reduces；Temperature reduces, DC reference signal Vref liter
High.Avoid temperature for the impact of output ripple；Ensure all to have under different temperatures preferably fall ripple effect,
Also can guarantee that circuit stability and efficiency optimization simultaneously.
Optionally, described Voltage loop control unit includes: subtractor and the first integrated transporting discharging；Described subtraction
One input of device receives DC reference signal Vref, and another input of described subtractor receives feedback
Signal VFB；The outfan of described subtractor is connected with an input of described first integrated transporting discharging；Institute
Another input stating the first integrated transporting discharging receives sampled signal VS；
Or, described Voltage loop control unit includes: adder and the second integrated transporting discharging；Described adder
Input receive feedback signal VFB；Another input of described adder receives sampled signal
VS；The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second
Another input of integrated transporting discharging receives DC reference signal Vref；
Wherein said feedback signal is identical with described output ripple phase place.
Or, optionally, described Voltage loop control unit includes: adder and the first integrated transporting discharging；Institute
The input stating adder receives described DC reference signal, another input termination of described adder
Receive described feedback signal；One input phase of the outfan of described adder and described first integrated transporting discharging
Even；Another input of described first integrated transporting discharging receives described sampled signal；
Or, described Voltage loop control unit includes: subtractor and the second integrated transporting discharging；Described subtractor
Input receive described feedback signal；Another input of described subtractor receives described sampling
Signal；The outfan of described subtractor is connected with an input of described second integrated transporting discharging；Described
Another input of two integrated transporting dischargings receives described DC reference signal；
Wherein, described feedback signal and described output ripple opposite in phase.
The effect of described block isolating circuit is that the AC compounent of the output voltage V1 obtaining described steady flow unit obtains
To feedback signal VFB, and it is input to described Voltage loop control unit；DC reference signal Vref and feedback
Signal VFB subtract each other after as the reference signal of sampled signal VS, VS exports after comparing with (Vref-VFB)
Described control signal；Or the described control signal of output is compared after VS with VFB superposition with Vref.Herein
It is not specifically limited, all in the protection domain of the application.
In another embodiment of this utility model, described sign non-isolation DC/DC converter unit output electricity
Sampled signal VS of pressure V2 directly obtains from the outfan of described non-isolation DC/DC converter unit, as
Shown in Fig. 5.
Preferably, as it is shown in figure 5, described steady flow unit includes: primary side winding, the first vice-side winding 401,
First switching tube K1, the first resistance R1, the first diode D1 and the first electric capacity C1；Wherein:
The anode of the first diode D1 and the Same Name of Ends of the first vice-side winding 401 are connected；
The negative electrode of the first diode D1 and one end of the first electric capacity C1 are connected；
The other end of the first electric capacity C1 and the different name end of the first vice-side winding 401 are connected；
The two ends of the first electric capacity C1 are respectively two outfans of described steady flow unit；
Different name end is described steady flow unit input of described primary side winding；
The Same Name of Ends of described primary side winding passes sequentially through the first switching tube K1 and the first resistance R1 and connects described
Another input of steady flow unit；
The control end of the first switching tube K1 receives and drives signal；.
Preferably, as it is shown in figure 5, described non-isolation DC/DC converter unit is buck circuit；Described
Non-isolation DC/DC converter unit includes: second switch pipe K2, the second diode D2 and the first inductance
L1；Wherein:
The input of second switch pipe K2 is an input of described non-isolation DC/DC converter unit；
The outfan of second switch pipe K2 and the negative electrode of the second diode D2 and one end of the first inductance L1
It is connected；
The anode of the second diode D2 is another input of described non-isolation DC/DC converter unit；
The other end of the first inductance L1 and the anode of the second diode D2 are respectively described non-isolation DC/DC
Two outfans of converter unit.
The input of described non-isolation DC/DC converter unit receives input voltage vin, in described non-isolated
The outfan parallel connection high-frequency filter capacitor (the i.e. second electric capacity C2) of DC/DC converter unit, makes described LED
Without high fdrequency component in the electric current of load.
Preferably, as it is shown in figure 5, feedback signal acquiring unit 103 includes: difference channel and every straight electricity
Road；Wherein:
Two inputs of described difference channel are connected with two outfans of described steady flow unit respectively；
The outfan of described difference channel is connected with the input of described block isolating circuit；
The input of the outfan of described block isolating circuit and described Voltage loop control unit and described DC reference
The input of acquiring unit is connected.
Preferably, as it is shown in figure 5, DC reference acquiring unit 104 includes: maximum value circuit；Described
The input of maximum value circuit is the input of described DC reference acquiring unit, connects described block isolating circuit
Outfan, the outfan of described maximum value circuit is the outfan of described DC reference acquiring unit, even
Receive another input of Voltage loop control unit.
Described maximum value circuit acquisition feedback signal VFB the maximum negating feedback signal VFB are direct current base
Calibration signal Vref.
Concrete, feedback signal acquiring unit 103 is obtained by described difference channel and described block isolating circuit
The AC compounent of the output voltage V1 of described steady flow unit；Owing to the maximum of AC signal is equivalent to ripple
The half of peak-to-peak value, so directly obtaining the output electricity of described steady flow unit by described maximum value circuit
The maximum of the AC compounent of pressure V1, just can obtain the output voltage V1 ripple peak-to-peak of described steady flow unit
The half of value: V1 ripple is the biggest, and the most described maximum is the biggest.DC reference acquiring unit 104 includes
It is worth greatly circuit, utilizes maximum value circuit to obtain DC reference signal Vref；
In concrete actual application, can enter using (Vref-VFB) as the reference signal of VS with VS
Row compares control second switch pipe K2 makes the AC compounent of its output voltage V2 and the AC compounent side of V1
To on the contrary, equal in magnitude；Or the superposed signal (VS+VFB) of VFB with VS is carried out with Vref
Relatively control second switch pipe K2 and make the AC compounent of its output voltage V2 and the AC compounent direction of V1
On the contrary, equal in magnitude.
Further, the above difference channel, all it is because common ground problem, if by defeated for steady flow unit 101
Go out end negative terminal directly as ground, then need not described difference channel, but now sampled signal VS will phase
Should change, so difference channel should in no way limit the protection domain of the application.
It should be noted that because main power circuit is described steady flow unit, the most described LED drive circuit
Export for current stabilization, then LED load size variation, the size of V1 also can respective change.
Particularly, under conditions of described LED drive circuit can also apply to light modulation, described LED drives
Circuit also includes dimming control unit, and the outfan output dim signal of described dimming control unit is to described
Steady flow unit, makes the output size of current of described steady flow unit change.Concrete dimming mode and existing
Technology is similar to, and during light modulation, the size of V1 also can respective change, i.e. V1 can change, and becomes
Change scope is determined by the output voltage range of described steady flow unit.When light modulation is used, because different electricity
Stream size, ripple varies in size, and arranges Vref and follows ripple size variation in real time, can guarantee that different electricity
The fall ripple effect flowed down and high efficiency, this circuit also has significant beneficial effect in light modulation is used.
In this utility model, each embodiment uses the mode gone forward one by one to describe, and each embodiment stresses
Being all the difference with other embodiments, between each embodiment, identical similar portion sees mutually.
For device disclosed in embodiment, owing to it corresponds to the method disclosed in Example, so describing
Fairly simple, relevant part sees method part and illustrates.
Below it is only preferred implementation of the present utility model, makes to skilled artisans appreciate that or real
Existing this utility model.To the multiple amendment of these embodiments will be to one skilled in the art aobvious and
Being clear to, generic principles defined herein can be without departing from spirit or scope of the present utility model
In the case of, realize in other embodiments.Therefore, this utility model is not intended to be limited to illustrated herein
These embodiments, and be to fit to consistent with principles disclosed herein and features of novelty the widest
Scope.
Claims (10)
1. a LED drive circuit, it is characterised in that including:
Control the steady flow unit of the stable current value of described LED drive circuit output；
It is provided commonly for driving the non-isolation DC/DC converter unit of LED load, institute with described steady flow unit
The outfan of the outfan and described non-isolation DC/DC converter unit of stating steady flow unit is connected；
Obtain the output ripple of described steady flow unit, and generate and described output stricture of vagina according to described output ripple
The feedback signal acquiring unit of the feedback signal that ripple is relevant；Described output ripple includes: output current ripple
And/or described output voltage ripple；The input of described feedback signal acquiring unit and described steady flow unit
Outfan is connected；
The DC reference generating the positively related DC reference signal of size with described output ripple obtains single
Unit；
Obtain a sampled signal characterizing described non-isolation DC/DC converter unit output voltage, and receive
Described feedback signal and described DC reference signal, make described non-isolation DC/DC according to described feedback signal
The opposite in phase of the output voltage ripple of the output voltage ripple of converter unit and described steady flow unit, and root
The output voltage average value making described non-isolation DC/DC converter unit according to described DC reference signal follows institute
The Voltage loop control unit stating the size of output ripple and change；The outfan of described Voltage loop control unit
It is connected with the control end of described non-isolation DC/DC converter unit；Two of described Voltage loop control unit defeated
Enter end respectively with the outfan of described DC reference acquiring unit and the output of described feedback signal acquiring unit
End is connected.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Acquiring unit includes: block isolating circuit；The input of described block isolating circuit and the outfan of described steady flow unit
Being connected, the outfan of described block isolating circuit is connected with the input of described Voltage loop control unit.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Acquiring unit includes:
Obtain the difference channel of the output parameter of described steady flow unit；Two inputs of described difference channel
It is connected with two outfans of described steady flow unit respectively；
The described feedback signal relevant to described steady flow unit output ripple is obtained according to described output parameter,
And described feedback signal is input to the block isolating circuit of described Voltage loop control unit；Described block isolating circuit
Input is connected with the outfan of described difference channel.
LED drive circuit the most according to claim 3, it is characterised in that described DC reference
Acquiring unit includes: obtain the maximum value circuit that feedback signal maximum is described DC reference signal；Institute
The input stating maximum value circuit connects the outfan of described block isolating circuit, the output of described maximum value circuit
End is the outfan of described DC reference acquiring unit.
LED drive circuit the most according to claim 1, it is characterised in that described DC reference
Acquiring unit includes: make described DC reference signal vary with temperature and the temperature sensing circuit of inverse change.
LED drive circuit the most according to claim 1, it is characterised in that described steady flow unit
For isolated form topology, described steady flow unit includes: primary side winding, the first vice-side winding, the first rectification mould
Block, the first resistance and the first switching tube；Wherein:
The outfan of described first vice-side winding is connected with the input of described first rectification module；
The outfan that outfan is described steady flow unit of described first rectification module；
Different name end is described steady flow unit input of described primary side winding；
The Same Name of Ends of described primary side winding passes sequentially through described first switching tube and described first resistance connects institute
State another input of steady flow unit；
The control end of described first switching tube receives and drives signal.
LED drive circuit the most according to claim 6, it is characterised in that described steady flow unit
Also include: the second vice-side winding and the second rectification module；The outfan of described second vice-side winding is with described
The input of the second rectification module is connected；The outfan of described second rectification module and described non-isolated
The input of DC/DC converter unit is connected.
LED drive circuit the most according to claim 1, it is characterised in that described Voltage loop control
Unit processed includes: adder and the first integrated transporting discharging；One input reception of described adder is described directly
Stream reference signal, another input of described adder receives described feedback signal；Described adder defeated
Go out end to be connected with an input of described first integrated transporting discharging；Another of described first integrated transporting discharging is defeated
Enter end and receive described sampled signal；
Or, described Voltage loop control unit includes: subtractor and the second integrated transporting discharging；Described subtractor
Input receive described feedback signal；Another input of described subtractor receives described sampling
Signal；The outfan of described subtractor is connected with an input of described second integrated transporting discharging；Described
Another input of two integrated transporting dischargings receives described DC reference signal；
Wherein, described feedback signal and described output ripple opposite in phase.
LED drive circuit the most according to claim 1, it is characterised in that described Voltage loop control
Unit processed includes: subtractor and the first integrated transporting discharging；One input reception of described subtractor is described directly
Stream reference signal, another input of described subtractor receives described feedback signal；Described subtractor defeated
Go out end to be connected with an input of described first integrated transporting discharging；Another of described first integrated transporting discharging is defeated
Enter end and receive described sampled signal；
Or, described Voltage loop control unit includes: adder and the second integrated transporting discharging；Described adder
Input receive described feedback signal；Another input of described adder receives described sampling
Signal；The outfan of described adder is connected with an input of described second integrated transporting discharging；Described
Another input of two integrated transporting dischargings receives described DC reference signal；
Wherein, described feedback signal is identical with described output ripple phase place.
10. according to the arbitrary described LED drive circuit of claim 1-9, it is characterised in that also include
Output dim signal, to described steady flow unit, makes the brightness adjustment control that the output electric current of described steady flow unit changes
Unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620352774.5U CN205546102U (en) | 2016-04-22 | 2016-04-22 | Light -emitting diode (LED) driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620352774.5U CN205546102U (en) | 2016-04-22 | 2016-04-22 | Light -emitting diode (LED) driving circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105792437A (en) * | 2016-04-22 | 2016-07-20 | 浙江英飞特光电有限公司 | LED drive circuit |
| CN109362141A (en) * | 2018-09-13 | 2019-02-19 | 华域视觉科技(上海)有限公司 | OLED light source drive control circuit and OLED luminaire |
-
2016
- 2016-04-22 CN CN201620352774.5U patent/CN205546102U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105792437A (en) * | 2016-04-22 | 2016-07-20 | 浙江英飞特光电有限公司 | LED drive circuit |
| CN109362141A (en) * | 2018-09-13 | 2019-02-19 | 华域视觉科技(上海)有限公司 | OLED light source drive control circuit and OLED luminaire |
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