CN104540306B - LED driver - Google Patents
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- CN104540306B CN104540306B CN201510031889.4A CN201510031889A CN104540306B CN 104540306 B CN104540306 B CN 104540306B CN 201510031889 A CN201510031889 A CN 201510031889A CN 104540306 B CN104540306 B CN 104540306B
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Abstract
The invention provides an LED driver. According to the LED driver disclosed by the invention, by virtue of serial connection of an AC-DC transform circuit and a BUCK circuit, LED load is driven; a current controlling loop is used for controlling a main switch tube of the BUCK circuit, so that the LED driver carries out output with steady flow; a voltage controlling loop is used for controlling a main switch tube of the AC-DC transform circuit, so that the sum of the output voltage of the AC-DC transform circuit and the input voltage of the BUCK circuit is larger than or instantly equal to the LED load voltage, the average value of the output voltage of the BUCK circuit is more than or equal to a half of peak-to-peak ripple in the output voltage of the AC-DC transform circuit, and therefore, the response speed of the voltage controlling loop can be designed to be slow so as to ensure high PE value and realize PFC function, and the response speed of the current controlling loop can be designed to be rapid so as to ensure low ripple of the output current of the LED driver and prevent the LED load from generating the stroboscopic phenomenon.
Description
Technical field
The present invention relates to field of LED drive technology, more particularly to a kind of LED driver.
Background technology
LED, as a kind of novel illumination device, as its luminous efficiency is high, is widely used in lighting field, and which is logical
Constant-current driving is needed often, the LED driver for driving as its current stabilization in the prior art is frequently with single-stage solution.
And the LED driver of single-stage solution is adopted, due to needing to take into account PFC (Power Factor Correction, work(
Rate factor correcting) function, i.e. its control loop need very slow response speed just have higher PF (Power Factor, work(
Rate factor) value, therefore, its control loop response speed is slower, and this can cause output current to have larger ripple, the ripple
Cycle for the input ac voltage cycle half.When LED driver connection is loaded, this current ripples will cause LED
There is stroboscopic phenomenon, this stroboscopic phenomenon will affect the service life of LED, also have certain damage to human eye.
The content of the invention
In view of this, the invention provides a kind of LED driver, has larger stricture of vagina to solve prior art output current
Ripple and cause LED the problem of stroboscopic phenomenon occur.
To achieve these goals, technical scheme provided in an embodiment of the present invention is as follows：
A kind of LED driver, including：
The AC-DC translation circuits and BUCK circuits of outfan series connection, the AC-DC translation circuits and BUCK circuits are used jointly
In driving LED load；
The current regulator that outfan is connected with the control end of main switch in the BUCK circuits, it is described for sampling
Electric current in BUCK circuits, and compare with a reference signal, the main switch of the BUCK circuits is controlled according to comparative result, is made
The LED driver current stabilization output；
The voltage control loop that outfan is connected with the control end of main switch in the AC-DC translation circuits, for detecting
The difference of the signal of the output voltage of the AC-DC translation circuits and the BUCK circuits is characterized, and is compared with reference value, according to
Comparative result controls the main switch of the AC-DC translation circuits, makes the output voltage of the AC-DC translation circuits and described
The input voltage sum of BUCK circuits is more than or is instantaneously equal to the LED load voltage, and makes the output of the BUCK circuits
Half of the average voltage more than or equal to ripple peak-to-peak value in the output voltage of the AC-DC translation circuits.
Preferably, response speed of the response speed of the current regulator more than the voltage control loop.
Preferably, the electric current in the BUCK circuits of the current regulator sampling is the inductance in the BUCK circuits
Electric current, the reference signal are preset signals.
Preferably, the electric current in the BUCK circuits of the current regulator sampling is the switch in the BUCK circuits
The electric current of pipe, the time of afterflow and frequency dependence of the amplitude of the reference signal and the BUCK circuits.
Preferably, also include：The constant pressure source being connected with the input of the BUCK circuits.
Preferably, the AC-DC translation circuits be isolated form topology, the first secondary in the AC-DC translation circuits around
Group is connected with the first rectification module, the outfan of the outfan of first rectification module as the AC-DC translation circuits；Institute
The second vice-side winding stated in AC-DC translation circuits is connected with the second rectification module, the outfan of second rectification module with
The input of the BUCK circuits is connected；
The BUCK circuits include：
The main switch that control end is connected with the outfan of the current regulator；The cold end of the main switch is
The negative terminal of the BUCK circuit input ends；
The diode that anode is connected with the hot end of the main switch；The negative electrode of the diode connects the BUCK
The anode of the anode and outfan of circuit input end；
The inductance that one end is connected with the anode of the diode；The other end of the inductance is the BUCK circuit output ends
Negative terminal；
The voltage control loop detection characterizes the signal of the output voltage of the AC-DC translation circuits and the BUCK circuits
Difference refer to, detect BUCK circuit output ends negative terminal and the negative terminal of BUCK circuit input ends between voltage difference.
Preferably, the reference value in the voltage control loop is with the LED load voltage non-monotonic decreasing.
Preferably, also include：Load voltage difference circuit, for detecting the LED load voltage, and the LED is born
Carry the reference ground identical voltage that voltage conversion is reference ground and the voltage control loop.
Preferably, when the reference value in the voltage control loop is with the LED load voltage monotonic increase, sample institute
The input voltage of BUCK circuits is stated, and using sampled signal as the reference value.
Preferably, the main switch in the BUCK circuits is arranged in same integrated circuit with the current regulator.
The application provides a kind of LED driver, drives after being connected with BUCK circuits by AC-DC translation circuits
LED load；Sampled the electric current in the BUCK circuits by current regulator, and compared with a reference signal, according to comparative result
The main switch of the BUCK circuits is controlled, the LED driver current stabilization output is made；Characterized by voltage control loop detection described
The difference of the signal of the output voltage of AC-DC translation circuits and the BUCK circuits, and compare with reference value, according to comparative result
The main switch of the AC-DC translation circuits is controlled, the output voltage and the BUCK circuits of the AC-DC translation circuits is made
Input voltage sum is more than or is instantaneously equal to the LED load voltage, and makes the output voltage average value of the BUCK circuits
More than or equal to the half of ripple peak-to-peak value in the output voltage of the AC-DC translation circuits.The LED provided herein drives
Dynamic device, by above-mentioned connected mode and control mode so that the response speed of the voltage control loop can design relatively slow, to protect
The higher PF values of card, realize PFC functions, therefore the response speed of the current regulator can be designed comparatively fast, it is ensured that the LED
The output current low ripple of driver, it is to avoid stroboscopic phenomenon occurs in LED load.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
Accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Inventive embodiment, for those of ordinary skill in the art, on the premise of not paying creative work, can be with basis
The accompanying drawing of offer obtains other accompanying drawings.
A kind of LED driver circuit figure that Fig. 1 is provided for the embodiment of the present application；
A kind of LED driver circuit figure that Fig. 2 is provided for another embodiment of the application；
A kind of LED driver circuit figure that Fig. 3 is provided for another embodiment of the application；
A kind of LED driver circuit figure that Fig. 4 is provided for another embodiment of the application；
A kind of LED driver circuit figure that Fig. 5 is provided for another embodiment of the application.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than the embodiment of whole.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.
A kind of LED driver is embodiments provided, there is larger ripple to solve prior art output current
And cause LED the problem of stroboscopic phenomenon occur.
Specifically, as shown in figure 1, the LED driver includes：
The AC-DC translation circuits 101 and BUCK circuits 102 of outfan series connection；
The current regulator 103 that outfan is connected with the control end of main switch in BUCK circuits 102；
The voltage control loop 104 that outfan is connected with the control end of main switch in AC-DC translation circuits 101.
What deserves to be explained is, in Fig. 1, the anode of the outfan of AC-DC translation circuits 101 is connected with the positive pole of LED load,
The negative terminal of the outfan of BUCK circuits 102 is connected with the negative pole of the LED load；In actual applications, it would however also be possible to employ BUCK
The anode of the outfan of circuit 102 is connected with the positive pole of LED load, the negative terminal of the outfan of AC-DC translation circuits 101 with it is described
The negative pole of LED load is connected；Fig. 1 is only a kind of example, AC-DC translation circuits 101 and BUCK circuits 102 and the LED load
Connected mode and be not specifically limited, can be according to its actual applied environment depending on.
Specifically operation principle is：
In prior art, the stroboscopic phenomenon for causing LED to occur in order to avoid output current has larger ripple is adopted
With the LED driver of two-step scheme also by more selection, the input of following stage DC-DC converter directly with prime AC-DC
The outfan of changer is connected, and the prime AC-DC converter is used to realize PFC functions that the rear class DC-DC converter to be used for
Constant current or pressure-keeping functions are realized, the control loop response speed of prime AC-DC converter can be very slow, without causing LED to drive
Dynamic device output current ripple problem, the control loop response speed of rear class DC-DC converter can be very fast, meets quick adjustment simultaneously
Reduce output current ripple demand, it is easy to solve the problems, such as single-stage solution.
But two-step scheme has carried out two times transfer due to input power, the efficiency for making LED driver is two-stage circuit
Efficiency product.Such as front stage circuits efficiency is η 1, and late-class circuit efficiency is η 2, then prior art is driven using the LED of two-step scheme
The efficiency eta of dynamic device=1 × η of η 2, greatly reduces the efficiency of LED driver, increases loss, it is impossible to highlight LED illumination System
The advantage of energy-conservation.
And adopt the LED driver that the present embodiment provides, AC-DC translation circuits 101 connect with BUCK circuits 102 after jointly
Drive the LED load；The electric current that current regulator 103 is sampled in the BUCK circuits, and compare with a reference signal, according to
The main switch of comparative result control BUCK circuits 102, makes the LED driver current stabilization output；Voltage control loop 104 detects table
The difference of the signal of the output voltage of AC-DC translation circuits 101 and BUCK circuits 102 is levied, and is compared with reference value, according to comparing
The main switch of output control AC-DC translation circuits 101, makes the output voltage and BUCK circuits 102 of AC-DC translation circuits 101
Input voltage sum be more than or be instantaneously equal to the LED load voltage, and make the output voltage average value of BUCK circuits 102
More than or equal to the half of ripple peak-to-peak value in the output voltage of AC-DC translation circuits 101.By above-mentioned connected mode and controlling party
Formula, the response speed of voltage control loop 104 can design relatively slow, to ensure higher PF values, realize PFC functions, so that
The response speed of current regulator 103 can be designed comparatively fast, it is ensured that the output current low ripple of the LED driver, it is to avoid institute
State LED load and stroboscopic phenomenon occur.Meanwhile, if the efficiency of AC-DC translation circuits 101 is η 1, the efficiency of BUCK circuits 102 is
η 2, then the efficiency eta of the LED driver be only slightly less than η 1, the efficiency eta of the LED driver is depended on less than the degree of η 1
The size of 102 processing power of BUCK circuits, compared to existing technology the LED driver efficiency high of middle employing two-step scheme and be lost
It is low.
What deserves to be explained is, the LED driver with Voltage loop in prior art, the Voltage loop detection LED driver are defeated
Go out voltage, and according to testing result and the comparison of reference voltage, control the switching tube of the translation circuit in LED driver, make LED
The output voltage of driver is the voltage under reference voltage setting.And the LED driver provided by the present embodiment, voltage
What control ring 104 was detected is not the output voltage of the LED driver, and will not also control the LED driver output voltage is
The voltage of a certain reference voltage setting, but signal and BUCK that detection characterizes the output voltage V1 of AC-DC translation circuits 101 are electric
The difference of the output voltage V2 signals on road 102, specifically includes：The output voltage V1 of AC-DC translation circuits 101 and BUCK circuits 102
Output voltage V2 difference V1-V2, characterize AC-DC translation circuits 101 output voltage V1 signal K × V1 and BUCK circuits
The output voltage V1 of difference K of 102 output voltage V2 × V1-V2, AC-DC translation circuit 101 and characterize the defeated of BUCK circuits 102
Go out the difference V1-K × V2 of the signal K × V2 of voltage V2, or the signal K1 for characterizing the output voltage V1 of AC-DC translation circuits 101
Difference K1 × V1-K2 × the V2 of × the V1 and signal K2 × V2 of the output voltage V2 for characterizing BUCK circuits 102；Again with reference value ratio
Compared with controlling AC-DC translation circuits 101 according to comparative result, make the output voltage V1 and BUCK circuit of AC-DC translation circuits 101
102 input voltage vin sum is more than or is instantaneously equal to the LED load voltage, and makes the output voltage of BUCK circuits 102
Half of the V2 meansigma methodss more than or equal to ripple peak-to-peak value in the output voltage of AC-DC translation circuits 101；Wherein, BUCK circuits 102
Output voltage V2 meansigma methodss more than or equal to AC-DC translation circuits 101 output voltage in ripple peak-to-peak value half, Ke Yibao
The output voltage of card BUCK circuits 102 is completely counterbalanced by all ripple components on 101 output voltage of AC-DC translation circuits, makes institute
Ripple current in LED load is stated close to zero；The input of the output voltage V1 and BUCK circuit 102 of AC-DC translation circuits 101
Voltage Vin sums are more than or are instantaneously equal to the LED load voltage, it is ensured that in the range of all of load voltage,
BUCK circuits 102 can normal closed loop work；Be not as in the prior art control LED driver output voltage it is constant,
Therefore, the LED driver that the present embodiment passes through applies to the load of wide scope, i.e., as the LED of different loads voltage
When load is connected to the LED driver of the present embodiment, the LED driver can export suitable voltage automatically, drive
The LED load works.
It should be noted that the input voltage vin of the output voltage V1 and BUCK circuit 102 of AC-DC translation circuits 101 it
With more than or be instantaneously equal to the LED load voltage, " be more than or be instantaneously equal to " therein refers specifically to：AC-DC translation circuits
Long-time is not equal to LED load voltage to the input voltage vin sum of 101 output voltage V1 and BUCK circuit 102, but：
The LED load voltage is both greater than within all times, or, equal to the LED load voltage under discrete N number of moment
Remaining when inscribe more than LED load voltage (N >=1).
In voltage control loop 104, when detection AC-DC translation circuits 101 output voltage V1 and BUCK circuit 102 it is defeated
When difference Vd for going out voltage V2 is compared with reference value Vref, AC-DC translation circuits 101 controlled according to comparative result, namely represent electricity
Pressure control ring 104 controls the output voltage of its output voltage V1 and BUCK circuits 102 by controlling AC-DC translation circuits 101
Difference Vd (Vd=V1-V2) of V2 is a definite value (definite value is determined by reference value Vref)；On the other hand, when LED driver connects
When connecing LED load, the output voltage Vo=V1+V2 of LED driver, and output voltage Vo is equal to LED load voltage, by loading
Determine, be a fixed value；To sum up, output voltage V1 and BUCK determined by reference value Vref, AC-DC translation circuits 101
Difference Vd of the output voltage V2 of circuit 102, is controlled as a fixed value, and determined by load voltage Vo, AC-DC conversion electricity
The output voltage V2 sums of the output voltage V1 and BUCK circuit 102 on road 101, are controlled as another fixed value, the two combination,
The output voltage V2 for being equivalent to the output voltage V1 and BUCK circuit 102 of control AC-DC translation circuits 101 is respectively corresponding solid
Definite value.
So when different loads is connected to LED driver, under the control of voltage control loop 104, AC-DC conversion electricity
The output voltage V2 of the output voltage V1 and BUCK circuit 102 on road 101 all have it is determining, unique, with one a pair of load phase
The value answered.Choose suitable reference value Vref, you can realize：Make the output voltage V1 and BUCK circuit of AC-DC translation circuits 101
102 input voltage vin sum is more than or is instantaneously equal to the LED load voltage, and makes the output voltage of BUCK circuits 102
Half of the V2 meansigma methodss more than or equal to ripple peak-to-peak value in the output voltage V1 of AC-DC translation circuits 101.
Preferably, response speed of the response speed of current regulator 103 more than voltage control loop 104.
The LED driver that the present embodiment is provided, relatively slow, the Ke Yibao of the response speed design of voltage control loop 104
The higher PF values of card, realize PFC functions；What now the response speed of current regulator 103 can be designed is very fast, it is ensured that described
The output current low ripple of LED driver, it is to avoid stroboscopic phenomenon occurs in the LED load.
Specifically, voltage control loop 104 is used for output voltage V1 and the BUCK circuits 102 for detecting AC-DC translation circuits 101
Output voltage V2 difference Vd, and compare with reference value Vref, the master of AC-DC translation circuits 101 controlled according to comparative result
Switching tube, makes the input voltage vin sum of the output voltage V1 and BUCK circuit 102 of AC-DC translation circuits 101 be more than or wink
When be equal to LED load voltage Vo, and make BUCK circuits 102 output voltage V2 meansigma methodss be more than or equal to AC-DC translation circuits 101
Output voltage V1 in ripple peak-to-peak value V11 half.
Difference Vd=V1-V2 of the detection of voltage control loop 104, voltage control loop 104 is by difference Vd and reference value Vref ratio
Compared with controlling the main switch of AC-DC translation circuits 101 according to comparative result, make while meeting：V1+Vin >=Vo, with V2 >=0.5
×V11；By V2 >=0.5 × V11, it is ensured that it is defeated that the output voltage of BUCK circuits 102 is completely counterbalanced by AC-DC translation circuits 101
The all ripple components gone out on voltage, make ripple current in the LED load close to zero；And because of the drop of BUCK circuits 102
Pressure is acted on, and be can ensure that in the range of all of load voltage by V1+Vin >=Vo, and BUCK circuits 102 can normal closed loop work
Make.
Or, voltage control loop 104 is used for the signal K × V1 for detecting the output voltage V1 for characterizing AC-DC translation circuits 101
With difference Vd of the output voltage V2 of BUCK circuits 102, and compare with reference value Vref, AC-DC is controlled according to comparative result and is become
The main switch of circuit 101 is changed, the input voltage vin of the output voltage V1 and BUCK circuit 102 of AC-DC translation circuits 101 is made
Sum is more than or is instantaneously equal to LED load voltage Vo, and is more than or equal to the output voltage V2 meansigma methodss of BUCK circuits 102
The half of ripple peak-to-peak value V11 in the output voltage V1 of AC-DC translation circuits 101.
Difference Vd=K × the V1-V2 of the detection of voltage control loop 104, voltage control loop 104 is by difference Vd and reference value Vref
Relatively, the main switch of AC-DC translation circuits 101 is controlled according to comparative result, is made while meeting：V1+Vin >=Vo, with V2 >=
0.5×V11；By V2 >=0.5 × V11, it is ensured that the output voltage of BUCK circuits 102 is completely counterbalanced by AC-DC translation circuits 101
All ripple components on output voltage, make ripple current in the LED load close to zero；And because of BUCK circuits 102
By V1+Vin >=Vo, hypotensive effect, can ensure that, in the range of all of load voltage, BUCK circuits 102 can normal closed loop
Work.
Preferably, the electric current in the BUCK circuits 102 of the sampling of current regulator 103 is the inductance electricity in BUCK circuits 102
Stream, the reference signal are preset signals.
The preset signals refer to the signal for pre-setting, namely the signal is unrelated with the running parameter in circuit, such as should
Switch periods, switching frequency, time of afterflow, service time or interrupting time when preset signals are worked with BUCK circuits 102 etc.
Running parameter is unrelated.But the preset signals can be that the constant level signal of amplitude, or amplitude become according to certain rule
The signal of change.
Or, as shown in Fig. 2 during the electric current in the BUCK circuits 102 of the sampling of current regulator 103 is BUCK circuits 102
Switching tube electric current, the amplitude of the reference signal and the time of afterflow of BUCK circuits 102 and frequency dependence.
If the electric current of the main switch in the sampling of current regulator 103 BUCK circuits 102, the amplitude of the reference signal with
The time of afterflow and frequency dependence of BUCK circuits 102.
This is due to the outputting current steadily of 103 BUCK circuits to be controlled 102 of current regulator, then to need acquisition BUCK electric
The output current on road 102, and in BUCK circuits 102 electric current of main switch and BUCK circuits 102 electric current inequivalence.Master opens
Although closing the electric current of pipe and the output current (output current of the electric current i.e. BUCK circuits 102 of inductance) of BUCK circuits 102
Peak value is equal, but the electric current of main switch is sawtooth waveforms, and its current duration is the ON time Ton of main switch, and electric
Inducing current is triangular wave, and the persistent period is the time of afterflow Toff sums of the ON time Ton with inductive current of main switch, i.e.,
Ton+Toff.Therefore, to the outputting current steadily of control BUCK circuits 102, and sampling is master switch in BUCK circuits 102
During the electric current of pipe, needs do corresponding process to the current sampling signal, or the reference signal to comparing therewith is done accordingly
Process, the output current of BUCK circuits 102 is obtained with the current sampling signal by main switch in BUCK circuits 102.For example
The amplitude of above-mentioned reference signal and time of afterflow and frequency dependence.
During electric current of the current regulator 103 in BUCK circuits 102 of sampling, can be with using above two mode；Herein not
It is specifically limited, in concrete application, can be depending on applied environment.
In a particular embodiment, as shown in Fig. 2 BUCK circuits 102 can also include being connected to BUCK circuits 102
High-frequency filter capacitor C between outfan.
In the outfan parallel connection high-frequency filter capacitor C of BUCK circuits 102, in making the electric current of the LED load, high frequency is not contained
Component；But when the inductive current of BUCK circuits 102 is detected, the current detection signal for being input to current regulator 103 is still adopted
With the high frequency electric for flowing through inductance L.
Preferably, the LED driver also includes：The constant pressure source being connected with the input of the BUCK circuits.
In the present embodiment, the input of BUCK circuits 102 can connect a constant pressure source, to provide constant input voltage.
Another embodiment of the present invention additionally provides another LED driver, as shown in figure 3, including：
The AC-DC translation circuits 101 and BUCK circuits 102 of outfan series connection；
The current regulator 103 that outfan is connected with the control end of master switch Q pipes in BUCK circuits 102；
The voltage control loop 104 that outfan is connected with the control end of main switch in AC-DC translation circuits 101.
In the LED driver that the present embodiment is provided, AC-DC translation circuits 101 are that isolated form is topological, AC-DC conversion
The first vice-side winding 111 in circuit 101 is connected with the first rectification module 112, the outfan conduct of the first rectification module 112
The outfan of AC-DC translation circuits 101；The second vice-side winding 113 and the second rectification module 114 in AC-DC translation circuits 101
It is connected, the outfan of the second rectification module 114 is connected with the input of BUCK circuits 102.
In the LED driver that the present embodiment is provided, BUCK circuits 102 include：
The main switch Q that control end is connected with the outfan of current regulator 103；The cold end of main switch Q is
The negative terminal of 102 input of BUCK circuits；
The diode D that anode is connected with the hot end of main switch Q；The negative electrode connection BUCK circuits 102 of diode D are defeated
Enter the anode of the anode and outfan at end；
The inductance L that one end is connected with the anode of diode D；The other end of inductance L is the negative of 102 outfan of BUCK circuits
End.
When the hot end of main switch Q is that main switch Q is turned on, electric current flows into one end of switching tube；Main switch Q's
When cold end is that switching tube is turned on, electric current flows out one end of switching tube.
Preferably, as shown in figure 3, input and the output respectively with BUCK circuits 102 of the input of voltage control loop 104
End is connected.
The detection of voltage control loop 104 characterizes the signal of the output voltage of AC-DC translation circuits 101 and BUCK circuits 102
Difference refers to, detect 102 outfan of BUCK circuits 102 input of negative terminal and BUCK circuits negative terminal between voltage difference.
When AC-DC translation circuits 101 are isolated form topology, the input voltage Vs of BUCK circuits 102 is using AC-DC conversion electricity
The output voltage of 101 second rectification module 114 of road, the now output voltage of the first rectification module 112 and the second rectification module 114
Proportional, then the output voltage V1 of the input voltage Vs and AC-DC translation circuit 101 of BUCK circuits 102 is also into this ratio,
Such as Vs/V1=K；If now voltage control loop 104 want to be designed to detect the output voltage V1 of AC-DC translation circuits 101 with
During difference V1-V2 of the output voltage V2 of BUCK circuits 102, it is also possible to by detecting the input voltage Vs of BUCK circuits 102 and defeated
Go out voltage V2, obtain K × V1-V2；So the input of voltage control loop 104 may be designed in respectively with BUCK circuits 102
Input be connected with outfan.
Now, the detection of voltage control loop 104 characterize the output voltage V1 of AC-DC translation circuits 101 signal K × V1 (
That is the input voltage Vs of BUCK circuits 102) difference Vd with the output voltage V2 of BUCK circuits 102, and with reference value Vref ratio
Compared with controlling the main switch of AC-DC translation circuits 101 according to comparative result, make the output voltage V1 of AC-DC translation circuits 101
It is more than with the input voltage vin sum of BUCK circuits 102 or is instantaneously equal to LED load voltage Vo, and makes BUCK circuits 102
Half of the output voltage V2 meansigma methodss more than or equal to ripple peak-to-peak value V11 in the output voltage V1 of AC-DC translation circuits 101.
Difference Vd=K × the V1-V2=Vs-V2 of the detection of voltage control loop 104, voltage control loop 104 is by difference Vd and base
Quasi- value Vref compares, and controls the main switch of AC-DC translation circuits 101 according to comparative result, makes while meeting：V1+Vin≥
Vo, with V2 >=0.5 × V11；By V2 >=0.5 × V11, it is ensured that the output voltage of BUCK circuits 102 is completely counterbalanced by AC-DC changes
The all ripple components changed on 101 output voltage of circuit, make ripple current in the LED load close to zero；And because of BUCK
By V1+Vin >=Vo, the hypotensive effect of circuit 102, can ensure that, in the range of all of load voltage, BUCK circuits 102 are all
Can normal closed loop work.
Preferably, reference value Vref in voltage control loop 104 is with the LED load voltage non-monotonic decreasing.
For example, reference value Vref of voltage control loop 104 can be taken with the LED load voltage monotonic increase.That is,
As the rising reference value of the LED load voltage is raised, as the reduction reference value of the LED load voltage is reduced.So,
The output voltage V2 of BUCK circuits 102 can be made to maintain one compared with the voltage of small magnitude, and it is defeated due to BUCK circuits 102
Go out electric current and constant current value is controlled to by current regulator 103, therefore, when reference value Vref is with the LED load voltage monotone variation
When, it is ensured that the output (or processing power) of BUCK circuits 102 maintains a relatively low level all the time, is conducive to institute
The efficiency for stating LED driver all keeps higher level in the range of wide load voltage.
Another embodiment of the present invention additionally provides another LED driver, as shown in figure 4, including：
The AC-DC translation circuits 101 and BUCK circuits 102 of outfan series connection；
The current regulator 103 that outfan is connected with the control end of master switch Q pipes in BUCK circuits 102；
The voltage control loop 104 that outfan is connected with the control end of main switch in AC-DC translation circuits 101.
The LED driver provided by the present embodiment also includes：Load voltage difference circuit 105, it is described for detecting
LED load voltage, and be reference ground and the reference ground identical voltage of voltage control loop 104 by the LED load voltage conversion.
Preferably, BUCK circuits 102 include：
The main switch Q that control end is connected with the outfan of current regulator 103；The cold end of main switch Q is
The negative terminal of 102 input of BUCK circuits；
The diode D that anode is connected with the hot end of main switch Q；The negative electrode connection BUCK circuits 102 of diode D are defeated
Enter the anode of the anode and outfan at end；
The inductance L that one end is connected with the anode of diode D；The other end of inductance L is the negative of 102 outfan of BUCK circuits
End.
Preferably, AC-DC translation circuits 101 are that isolated form is topological, the first vice-side winding in AC-DC translation circuits 101
111 are connected with the first rectification module 112, the outfan of the outfan of the first rectification module 112 as AC-DC translation circuits 101；
The second vice-side winding 113 in AC-DC translation circuits 101 is connected with the second rectification module 114, the second rectification module 114 it is defeated
Go out end to be connected with the input of BUCK circuits 102.
In embodiment shown in Fig. 4, the amplitude of reference value Vref is with the amplitude monotonic increase of the LED load voltage Vo.
Due to voltage control loop 104 reference ground for BUCK circuits 102 input voltage Vs input negative terminal；Specifically applying
In, in voltage control loop 104, the reference ground of the reference ground and difference Vd of amplifier can also be the input voltage of BUCK circuits 102
The negative terminal of the input of Vs, so the reference ground of reference value Vref should also be the input of the input voltage Vs of BUCK circuits 102
The negative terminal at end.And the negative terminal of the input of the input voltage Vs of BUCK circuits 102 is with load voltage Vo not altogether, accordingly, it would be desirable to
The LED load voltage Vo is converted to load voltage difference circuit 105 input of the input voltage Vs with BUCK circuits 102
Negative terminal for reference ground voltage.
Preferably, as shown in figure 5, reference value Vref in voltage control loop 104 is with the LED load voltage monotonic increase
When, the input voltage Vs of BUCK circuits 102 of sampling, and using sampled signal as reference value Vref.
Fig. 4 and Fig. 5 is a kind of value mode of reference value Vref, in specific practical application, can be according to reality
Situation is selected, and is not specifically limited herein.
Preferably, the main switch in the BUCK circuits is arranged in same integrated circuit with the current regulator.
The integration section of the BUCK circuits and the current regulator, can be according to specific applicable cases depending on, this
Place is not specifically limited.
In the present invention, each embodiment is described by the way of progressive, and what each embodiment was stressed is and other realities
Apply the difference of example, between each embodiment identical similar portion mutually referring to.For device disclosed in embodiment
Speech, as which corresponds to the method disclosed in Example, so description is fairly simple, related part is referring to method part illustration
.
The above is only the preferred embodiment of the present invention, make skilled artisans appreciate that or realizing the present invention.It is right
Various modifications of these embodiments will be apparent to one skilled in the art, general original as defined herein
Reason can be realized without departing from the spirit or scope of the present invention in other embodiments.Therefore, the present invention will not
Be intended to be limited to the embodiments shown herein, and be to fit to it is consistent with principles disclosed herein and features of novelty most
Wide scope.
Claims (10)
1. a kind of LED driver, it is characterised in that include：
The AC-DC translation circuits and BUCK circuits of outfan series connection, the AC-DC translation circuits and BUCK circuits are provided commonly for driving
Dynamic LED load；
The current regulator that outfan is connected with the control end of main switch in the BUCK circuits, it is electric for the BUCK that samples
Electric current in road, and compare with a reference signal, the main switch of the BUCK circuits is controlled according to comparative result, is made described
LED driver current stabilization is exported；
The voltage control loop that outfan is connected with the control end of main switch in the AC-DC translation circuits, characterizes for detecting
The difference of the signal of the output voltage of the AC-DC translation circuits and the BUCK circuits, and comparing with reference value, according to comparing
The main switch of AC-DC translation circuits described in output control, makes the output voltage and the BUCK of the AC-DC translation circuits electric
The input voltage sum on road is more than or is instantaneously equal to the LED load voltage, and puts down the output voltage of the BUCK circuits
Half of the average more than or equal to ripple peak-to-peak value in the output voltage of the AC-DC translation circuits.
2. LED driver according to claim 1, it is characterised in that the response speed of the current regulator is more than institute
State the response speed of voltage control loop.
3. LED driver according to claim 1, it is characterised in that the BUCK of the current regulator sampling is electric
Electric current in road is the inductive current in the BUCK circuits, and the reference signal is preset signals.
4. LED driver according to claim 1, it is characterised in that the BUCK of the current regulator sampling is electric
Electric current in road is the electric current of the switching tube in the BUCK circuits, and the amplitude of the reference signal is continuous with the BUCK circuits
Stream time and frequency dependence.
5. LED driver according to claim 1, it is characterised in that also include：With the input phase of the BUCK circuits
Constant pressure source even.
6. LED driver according to claim 1, it is characterised in that the AC-DC translation circuits are isolated form topology,
The first vice-side winding in the AC-DC translation circuits is connected with the first rectification module, the outfan of first rectification module
As the outfan of the AC-DC translation circuits；The second vice-side winding and the second rectification module in the AC-DC translation circuits
It is connected, the outfan of second rectification module is connected with the input of the BUCK circuits；
The BUCK circuits include：
The main switch that control end is connected with the outfan of the current regulator；The cold end of the main switch is described
The negative terminal of BUCK circuit input ends；
The diode that anode is connected with the hot end of the main switch；The negative electrode of the diode connects the BUCK circuits
The anode of the anode and outfan of input；
The inductance that one end is connected with the anode of the diode；The other end of the inductance is the negative of the BUCK circuit output ends
End；
The voltage control loop detection characterizes the difference of the signal of the output voltage of the AC-DC translation circuits and the BUCK circuits
Value refers to, detects the voltage difference between the negative terminal and the negative terminal of BUCK circuit input ends of BUCK circuit output ends.
7. LED driver according to claim 1, it is characterised in that the reference value in the voltage control loop with
The LED load voltage monotonic increase.
8. LED driver according to claim 7, it is characterised in that also include：Load voltage difference circuit, for examining
The LED load voltage is surveyed, and is that reference ground is identical with the reference ground of the voltage control loop by the LED load voltage conversion
Voltage.
9. the LED driver according to claim 6 or 7, it is characterised in that the reference value in the voltage control loop
During with the LED load voltage monotonic increase, the input voltage of the BUCK circuits of sampling, and using sampled signal as the base
Quasi- value.
10. LED driver according to claim 1, it is characterised in that the main switch in the BUCK circuits with it is described
Current regulator is arranged in same integrated circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510031889.4A CN104540306B (en) | 2015-01-22 | 2015-01-22 | LED driver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510031889.4A CN104540306B (en) | 2015-01-22 | 2015-01-22 | LED driver |
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| Publication Number | Publication Date |
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| CN104540306A CN104540306A (en) | 2015-04-22 |
| CN104540306B true CN104540306B (en) | 2017-04-12 |
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|---|---|---|---|
| CN201510031889.4A Active CN104540306B (en) | 2015-01-22 | 2015-01-22 | LED driver |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106160434B (en) * | 2016-07-22 | 2020-05-15 | 矽力杰半导体技术(杭州)有限公司 | Ripple wave suppression method and circuit and load driving circuit applying same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100950913B1 (en) * | 2007-11-29 | 2010-04-01 | 삼성전기주식회사 | DC/DC Converter |
| US8536808B2 (en) * | 2011-11-23 | 2013-09-17 | Tower Semiconductor Ltd. | CMOS bootstrap circuit for DC/DC buck converter using low voltage CMOS diode |
| CN202424506U (en) * | 2012-01-11 | 2012-09-05 | 西南交通大学 | Single-stage high power factor correction converter with low output power frequency ripple wave |
| CN104270020A (en) * | 2014-09-10 | 2015-01-07 | 康佳集团股份有限公司 | BUCK topology self-adaptation current ripple adjusting circuit inside driving circuit |
| CN204392645U (en) * | 2015-01-22 | 2015-06-10 | 英飞特电子（杭州）股份有限公司 | A kind of LED driver |
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