CN104703346B - A kind of LED driver - Google Patents
A kind of LED driver Download PDFInfo
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- CN104703346B CN104703346B CN201510078148.1A CN201510078148A CN104703346B CN 104703346 B CN104703346 B CN 104703346B CN 201510078148 A CN201510078148 A CN 201510078148A CN 104703346 B CN104703346 B CN 104703346B
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Abstract
The application provides a kind of LED driver, and LED load is driven by AC DC translation circuits and BUCK circuit connected in series；The main switch of BUCK circuits is controlled by current regulator to realize that current stabilization is exported；By signal processing circuit to detecting that the difference of signal is exported to voltage control loop after carrying out peak holding processing or valley holding processing, control the main switch of AC DC translation circuits, the output voltage of AC DC translation circuits and the input voltage sum of BUCK circuits is more than or instantaneously be equal to LED load voltage, and the output voltage average value of BUCK circuits is more than or equal to the half of ripple peak-to-peak value in the output voltage of AC DC translation circuits；Allow the response speed of voltage control loop to design relatively slow, to ensure higher PF values, realize PFC functions, the response speed of current regulator can be designed comparatively fast, it is ensured that the output current low ripple of LED driver, it is to avoid stroboscopic phenomenon occurs in LED load.
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, because its luminous efficiency is high, is widely used in lighting field, and it is logical
Often constant current is needed to drive, the LED driver driven in the prior art as its current stabilization is frequently with single-stage solution.
And the LED driver of single-stage solution is used, due to needing to take into account PFC (Power Factor Correction, work(
Rate factor correcting) function, i.e. its control loop need the very slow response speed just to have higher PF (Power Factor, work(
Rate factor) value, therefore, its control loop response speed is slower, and this can cause the output current to have larger ripple, the ripple
Cycle be the input ac voltage cycle half.When LED driver is connected and loaded, this current ripples will cause LED
There is stroboscopic phenomenon, this stroboscopic phenomenon will influence the service life of LED, also there is certain damage to human eye.
The content of the invention
In view of this, the invention provides a kind of LED driver, there is larger line to solve prior art output current
Ripple and cause the problem of stroboscopic phenomenon occurs in LED.
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 output end series connection, the AC-DC translation circuits and BUCK circuits are used jointly
In driving LED load；
The current regulator that output end is connected with the control end of main switch in the BUCK circuits, institute is flowed through for detecting
The electric current of LED load is stated, and is compared 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；
Signal processing circuit, signal and the BUCK circuits for detecting the output voltage for characterizing AC-DC translation circuits
Output voltage signal difference signal, and to the difference signal carry out peak holding processing or valley holding processing after it is defeated
Go out low ripple difference signal；
The voltage control loop that output end is connected with the control end of main switch in the AC-DC translation circuits, the voltage
The input of control ring is connected with the output end of the signal processing circuit, for receiving the low ripple difference signal, and with
A reference value compares, and the main switch of the AC-DC translation circuits is controlled according to comparative result, makes the AC-DC translation circuits
The input voltage sum of output voltage and the BUCK circuits is more than or is instantaneously equal to the LED load voltage, and makes described
The output voltage average value of BUCK circuits is more than or equal to one of ripple peak-to-peak value in the output voltage of the AC-DC translation circuits
Half.
It is preferred that, the response speed of the current regulator is more than the response speed of the voltage control loop.
It is preferred that, the AC-DC translation circuits are isolated form topology, the first secondary in the AC-DC translation circuits around
Group is connected with the first rectification module, the output end of first rectification module as the AC-DC translation circuits output end；Institute
The second vice-side winding stated in AC-DC translation circuits is connected with the second rectification module, the output end 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 output end of the current regulator；The cold end of the main switch is
The negative terminal of the BUCK circuit input ends；
The first diode that anode is connected with the hot end of the main switch；The negative electrode connection of first diode
The anode of the BUCK circuit input ends and the anode of output end；
The inductance that one end is connected with the anode of first diode；The other end of the inductance is that the BUCK circuits are defeated
Go out the negative terminal at end.
It is preferred that, the signal processing circuit includes：
The second diode that anode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity that one end is connected with the negative electrode of second diode；The other end of the electric capacity and the BUCK circuits are defeated
The negative terminal for entering end is connected；
It is parallel to the resistance at the electric capacity two ends；The company of the negative electrode of second diode and the electric capacity and the resistance
Contact is connected with the input of the voltage control loop.
It is preferred that, the signal processing circuit includes：
The second diode that anode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity that one end is connected with the negative electrode of second diode；The other end of the electric capacity and the BUCK circuits are defeated
The negative terminal for entering end is connected；
The first resistor and second resistance being connected in series；The tie point of the first resistor and the second resistance with it is described
The input of voltage control loop is connected；The negative electrode and the electric capacity of the other end of the first resistor and second diode
Tie point is connected；The tie point phase of the other end of the second resistance and the electric capacity and the negative terminal of the BUCK circuit input ends
Even.
It is preferred that, the signal processing circuit also includes：
The 3rd resistor and first switch being connected in series；One end phase of the other end of the 3rd resistor and the electric capacity
Even, the other end of the first switch is connected with the other end of the electric capacity；The first switch is used to turn under heavy loads,
Turned off under underloading.
It is preferred that, the signal processing circuit also includes：
It is connected to the 4th resistance between the electric capacity and the first resistor；
The second switch being connected with the 4th resistor coupled in parallel, for turning under heavy loads, is turned off under underloading.
It is preferred that, the signal processing circuit also includes：
The comparator that output end is connected with the anode of second diode；The in-phase input end of the comparator with it is described
The negative terminal of BUCK circuit output ends is connected, and the inverting input of the comparator is connected with the negative electrode of second diode.
It is preferred that, the signal processing circuit includes：
The second diode that negative electrode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity that one end is connected with the anode of second diode；The other end of the electric capacity and the BUCK circuits are defeated
The negative terminal for entering end is connected；
It is parallel to the resistance at the second diode two ends；The anode of second diode and the electric capacity and the electricity
The tie point of resistance is connected with the input of the voltage control loop.
It is preferred that, the signal processing circuit also includes：
The comparator that output end is connected with the negative electrode of second diode；The in-phase input end of the comparator with it is described
The negative terminal of BUCK circuit output ends is connected, and the inverting input of the comparator is connected with the anode of second diode.
It is preferred that, a reference value in the voltage control loop is with the LED load voltage non-monotonic decreasing.
It is preferred that, also include：Load voltage difference circuit, bears for detecting the LED load voltage, and by the LED
It is reference ground and the reference ground identical voltage of the voltage control loop to carry voltage conversion.
It is preferred that, when a 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 regard sampled signal as a reference value.
It is preferred that, 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, is driven after being connected by AC-DC translation circuits with BUCK circuits
LED load；The electric current for flowing through the LED load is detected by current regulator, and is compared with a reference signal, according to comparative result
The main switch of the BUCK circuits is controlled, the LED driver current stabilization is exported；AC- is characterized by signal processing circuit detection
The difference signal of the signal of the output voltage of the signal of the output voltage of DC translation circuits and the BUCK circuits, and to the difference
Value signal exports low ripple difference signal after carrying out peak holding processing or valley holding processing；Receive described by voltage control loop
Low ripple difference signal, and compared with a reference value, the main switch of the AC-DC translation circuits is controlled according to comparative result, is made
The input voltage sum of the output voltage of the AC-DC translation circuits and the BUCK circuits is more than or is instantaneously equal to described
LED load voltage, and the output voltage average value of the BUCK circuits is more than or equal to the output electricity of the AC-DC translation circuits
The half of ripple peak-to-peak value in pressure.The LED driver provided herein, by above-mentioned connected mode and control mode,
Allow the response speed of the voltage control loop to design relatively slow, to ensure higher PF values, realize PFC functions, therefore institute
Stating the response speed of current regulator can design comparatively fast, it is ensured that the output current low ripple of the LED driver, it is to avoid LED
There is stroboscopic phenomenon in load.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
The 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
The embodiment of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can also basis
The accompanying drawing of offer obtains other accompanying drawings.
A kind of LED driver circuit figure that Fig. 1 provides for the embodiment of the present application；
A kind of LED driver circuit figure that Fig. 2 provides for another embodiment of the application；
A kind of LED driver circuit figure that Fig. 3 provides for another embodiment of the application；
A kind of signal waveforms that Fig. 4 provides for another embodiment of the application；
A kind of signal processing circuit figure that Fig. 5 provides for another embodiment of the application；
A kind of signal processing circuit figure that Fig. 6 provides for another embodiment of the application；
A kind of signal waveforms that Fig. 7 provides for another embodiment of the application；
A kind of signal processing circuit figure that Fig. 8 provides for another embodiment of the application；
A kind of signal processing circuit figure that Fig. 9 provides for another embodiment of the application；
A kind of signal processing circuit figure that Figure 10 provides for another embodiment of the application；
A kind of signal processing circuit figure that Figure 11 provides for another embodiment of the application；
A kind of signal waveforms that Figure 12 provides for another embodiment of the application；
A kind of signal processing circuit figure that Figure 13 provides for another embodiment of the application；
A kind of LED driver circuit figure that Figure 14 provides for another embodiment of the application；
A kind of LED driver circuit figure that Figure 15 provides for another embodiment of the application.
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 whole embodiments.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.
The embodiments of the invention provide a kind of LED driver, there is larger ripple to solve prior art output current
And cause the problem of stroboscopic phenomenon occurs in LED.
Specifically, as shown in figure 1, the LED driver includes：
The AC-DC translation circuits 101 and BUCK circuits 102 of output end series connection；
The current regulator 103 that output end is connected with the control end of main switch in BUCK circuits 102；
The voltage control loop 104 that output end is connected with the control end of main switch in AC-DC translation circuits 101；
The signal processing circuit 105 that output end is connected with the input of voltage control loop 104.
What deserves to be explained is, the anode of the output end of AC-DC translation circuits 101 is connected with the positive pole of LED load in Fig. 1,
The negative terminal of the output end 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 output end of circuit 102 is connected with the positive pole of LED load, the negative terminal of the output end 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 the prior art, in order to avoid the stroboscopic phenomenon that output current has larger ripple and causes LED to occur, adopt
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 output end of converter is connected, and the prime AC-DC converter is used to realize PFC functions, and the rear class DC-DC converter is 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 solution single-stage solution the problem of exist.
But two-step scheme has carried out two times transfer due to input power, it is two-stage circuit to make the efficiency of LED driver
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
Efficiency eta=1 × η of η 2 of dynamic device, greatly reduce the efficiency of LED driver, increase loss, it is impossible to highlight LED illumination System
The advantage of energy-conservation.
And the LED driver of the present embodiment offer is provided, AC-DC translation circuits 101 are common after being connected with BUCK circuits 102
Drive the LED load；Current regulator 103 detects the electric current for flowing through the LED load, and is compared with a reference signal, root
The main switch of BUCK circuits 102 is controlled according to comparative result, the LED driver current stabilization is exported；Signal processing circuit 105 is examined
Survey the difference letter of the signal of the signal for the output voltage for characterizing AC-DC translation circuits 101 and the output voltage of BUCK circuits 102
Number, and to exporting low ripple difference signal after difference signal progress peak holding processing or valley holding processing；Voltage control
Ring 104 processed receives the low ripple difference signal, and is compared with a reference value, and AC-DC translation circuits 101 are controlled according to comparative result
Main switch, the output voltage of AC-DC translation circuits 101 and the input voltage sum of BUCK circuits 102 is more than or wink
When be equal to the LED load voltage, and make BUCK circuits 102 output voltage average value be more than or equal to AC-DC translation circuits 101
Output voltage in ripple peak-to-peak value half.
It should be noted that peak holding refers to the output letter of corresponding peak holding circuit in signal processing circuit 105
Number it is equal or approximately equal with the crest voltage of input signal；And valley keeps referring to corresponding paddy in signal processing circuit 105
The output signal of value holding circuit and the valley point voltage of input signal are equal or approximately equal.Kept by peak holding or valley
Output signal afterwards, the ripple compared to input signal is low.
LED driver described in the present embodiment, passes through above-mentioned connected mode and control mode, the sound of voltage control loop 104
Answer speed to design relatively slow, to ensure higher PF values, realize PFC functions, so that the response speed of current regulator 103
Degree can design very fast, it is ensured that the output current low ripple of the LED driver, it is to avoid stroboscopic phenomenon occurs in the LED load.
Meanwhile, if the efficiency of AC-DC translation circuits 101 is η 1, the efficiency of BUCK circuits 102 is η 2, the then LED driver effect
Rate η is only slightly less than η 1, and the efficiency eta of the LED driver is less than η 1 degree depending on the big of the processing power of BUCK circuits 102
It is small, compared with prior art the LED driver efficiency high of middle use two-step scheme and be lost low.
The LED driver that the present embodiment is provided, because the output end of AC-DC translation circuits 101 and the output end of BUCK circuits 102
Connect and connect the LED load, therefore, current regulator 103 detects the electric current for flowing through the LED load, inspection can be passed through
Survey the electric current of the output loop of BUCK circuits 102, or the electric current of the output loop of AC-DC translation circuits 101 to realize, sampling is connected back
The electric current of any point on road, all equivalent or identical with load current, Fig. 1 is only a kind of example, is not specifically limited herein.
What deserves to be explained is, the LED driver with Voltage loop in the prior art, Voltage loop detection LED driver is defeated
Go out voltage, and according to the comparison of testing result and 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 that the present embodiment is provided, voltage
Control ring 104 is not the voltage for controlling the LED driver output voltage to be the setting of a certain reference voltage, but by signal
Manage signal and the output voltage V2 of BUCK circuits 102 that the detection of circuit 105 characterizes the output voltage V1 of AC-DC translation circuits 101
Signal difference signal, specifically include：The output voltage V1 of AC-DC translation circuits 101 and the output voltage of BUCK circuits 102
V2 difference V1-V2, the output electricity of the output voltage V1 of sign AC-DC translation circuits 101 signal K × V1 and BUCK circuits 102
Press the output voltage V2's of output voltage V1 and sign the BUCK circuit 102 of V2 difference K × V1-V2, AC-DC translation circuit 101
Signal K × V2 difference V1-K × V2, or characterize the output voltage V1 of AC-DC translation circuits 101 signal K1 × V1 and sign
The output voltage V2 of BUCK circuits 102 signal K2 × V2 difference K1 × V1-K2 × V2；Compared again with a reference value, according to comparing
Output control AC-DC translation circuits 101, make the input electricity of output voltage V1 and the BUCK circuit 102 of AC-DC translation circuits 101
Pressure Vin sums are more than or are instantaneously equal to the LED load voltage, and make the output voltage V2 average values of BUCK circuits 102 big
The half of ripple peak-to-peak value in the output voltage equal to AC-DC translation circuits 101.Wherein, the output voltage of BUCK circuits 102
V2 average values are more than or equal to the half of ripple peak-to-peak value in the output voltage of AC-DC translation circuits 101, it is ensured that BUCK circuits
102 output voltage is completely counterbalanced by all ripple components on the output voltage of AC-DC translation circuits 101, makes in the LED load
Ripple current close to zero；The input voltage vin sum of output voltage V1 and the BUCK circuit 102 of AC-DC translation circuits 101
It is more than or is instantaneously equal to the LED load voltage, it is ensured that in the range of all load voltages, BUCK circuits 102 is all
Can normal closed loop work；It is not to control the output voltage of LED driver constant as in the prior art, therefore, the present embodiment
The LED driver passed through applies to the load of wide scope, i.e., when the LED load of different loads voltage is connected to this reality
When applying the LED driver of example, the LED driver can export suitable voltage automatically, drive the LED load to work.
It should be noted that prior art has a larger ripple to solve output current and causes LED frequency occur
Flash as the problem of, with the presence of following scheme：The output voltage and BUCK for characterizing AC-DC translation circuits are detected by voltage control loop
The difference of the signal of the output voltage of circuit, then after the difference and an a reference value are compared, according to comparative result control
The main switch of the AC-DC translation circuits, makes the input of the output voltage and the BUCK circuits of the AC-DC translation circuits
Voltage sum is more than or is instantaneously equal to the LED load voltage, and is more than the output voltage average value of the BUCK circuits
Equal to the half of ripple peak-to-peak value in the output voltage of the AC-DC translation circuits.But, it is defeated due to AC-DC translation circuits
Going out the output voltage of voltage and BUCK circuits all has a ripple, and the two ripple opposite in phase (meanwhile, LED load voltage is
Sum of the two, also just because of two voltage ripples mutually amplitude is equal on the contrary, the ripple that can just make the voltage of LED load be zero), because
The difference of this output voltage and the signal of the output voltage of BUCK circuits for characterizing AC-DC translation circuits is the electricity of one big ripple
Signal is pressed, if directly handled by voltage control loop, the reduction of system PF values can be caused；Or, to reduce voltage control
The response speed of the ring PF value higher to ensure system, but dynamic response effect can be caused poor.LED drivings described in the present embodiment
Device, carries out peak holding processing by signal processing circuit 105 or valley holding is handled, reduce and be input to voltage control loop
The ripple of 104 signal, it is to avoid the generation of above mentioned problem.
It should be noted that the input voltage vin of output voltage V1 and the BUCK circuit 102 of AC-DC translation circuits 101 it
Be more than or instantaneously be equal to the LED load voltage, " be more than or be instantaneously equal to " therein refers specifically to：AC-DC translation circuits
The input voltage vin sum of 101 output voltage V1 and BUCK circuit 102 is not equal to LED load voltage for a long time, 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 for positive integer) more than or equal to 1.
It is preferred that, the response speed of current regulator 103 is more than the response speed of 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, signal processing circuit 105 is used for the signal for detecting the output voltage V1 for characterizing AC-DC translation circuits 101
With the difference signal Vd of the output voltage V2 of BUCK circuits 102 signal, and to difference signal Vd carry out drop ripple processing after it is defeated
Go out low ripple difference signal Vd1；Low ripple difference signal Vd1 is received by voltage control loop 104, and compared with a reference value Vref,
The main switch of AC-DC translation circuits 101 is controlled according to comparative result, make AC-DC translation circuits 101 output voltage V1 and
The input voltage vin sum of BUCK circuits 102 is more than or is instantaneously equal to LED load voltage Vo, and makes the defeated of BUCK circuits 102
Go out half of the voltage V2 average values more than or equal to ripple V11 peak-to-peak values in the output voltage V1 of AC-DC translation circuits 101.
The difference Vd=V1-V2 that signal processing circuit 105 is detected, and difference Vd progress peak holding processing or valley are protected
Hold output low ripple difference signal Vd1 after processing；Voltage control loop 104 is by low ripple difference signal Vd1 and a reference value Vref ratios
Compared with controlling the main switch of AC-DC translation circuits 101 according to comparative result, make satisfaction simultaneously：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
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 is that can ensure in the range of all load voltages by V1+Vin >=Vo, BUCK circuits 102 can normal closed loop work
Make.
Or, signal processing circuit 105 be used to detecting the output voltage V1 for characterizing AC-DC translation circuits 101 signal K ×
V1 and the output voltage V2 of BUCK circuits 102 difference Vd, and difference Vd progress peak holding processing or valley holding are handled
Low ripple difference signal Vd1 is exported afterwards；Low ripple difference signal Vd1 is received by voltage control loop 104, and with a reference value Vref ratios
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
Output voltage V2 average values are more than or equal to the half of ripple peak-to-peak value V11 in the output voltage V1 of AC-DC translation circuits 101.
Difference Vd=K × V1-V2 that signal processing circuit 105 is detected, and peak holding processing or paddy are carried out to difference Vd
It is worth output low ripple difference signal Vd1 after holding processing；Voltage control loop 104 is by low ripple difference signal Vd1 and a reference value
Vref compares, and the main switch of AC-DC translation circuits 101 is controlled according to comparative result, makes to meet simultaneously：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 conversion electricity
All ripple components on the output voltage of road 101, make ripple current in the LED load close to zero；And because of BUCK circuits
102 antihypertensive effect, is that can ensure in the range of all load voltages by V1+Vin >=Vo, BUCK circuits 102 can be just
Normal Closed loop operation.
It is preferred that, current regulator 103 is used to detect the inductive current in BUCK circuits 102, and the reference signal is pre-
If signal.
The preset signals refer to the signal pre-set, 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 work 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 current regulator 103 is used for the electric current for detecting the switching tube in BUCK circuits 102, it is described
The amplitude of reference signal and the time of afterflow and frequency dependence of BUCK circuits 102.
If the electric current of the main switch in the detection 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 the BUCK circuits 102 to be controlled of current regulator 103, then needs detection BUCK electricity
The output current on road 102, and the electric current and inequivalence of the electric current of main switch and BUCK circuits 102.Though the electric current of main switch
It is so equal with output current (i.e. output current of the electric current BUCK circuits 102 of inductance) peak value of BUCK circuits 102 but main
The electric current of switching tube is sawtooth waveforms, and its current duration is the ON time Ton of main switch, and inductive current is triangle
Ripple, the duration is the ON time Ton of main switch and the time of afterflow Toff sums of inductive current, i.e. Ton+Toff.If
Control the outputting current steadily of BUCK circuits 102, and detect be the electric current of main switch when, it is necessary to believe the current sample
Number corresponding processing is done, or corresponding processing is done to the reference signal compared therewith.The amplitude of reference signal as escribed above
With time of afterflow and frequency dependence.
Current regulator 103 can use above two mode in the electric current in detecting BUCK circuits 102；Herein not
It is specifically limited, can be depending on applied environment in concrete application.
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 output end.
In the output end of BUCK circuits 102 high-frequency filter capacitor C in parallel, make to be free of high frequency in the electric current of the LED load
Component；But when detecting the inductive current of BUCK circuits 102, the current detection signal for being input to current regulator 103 is still adopted
With the high frequency electric for flowing through inductance L.
It is preferred that, the LED driver also includes：The constant pressure source being connected with the input of the BUCK circuits.
The input of BUCK circuits 102 can connect a constant pressure source in the present embodiment, 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 output end series connection；
The current regulator 103 that output end is connected with the control end of main switch Q pipes in BUCK circuits 102；
The voltage control loop 104 that output end is connected with the control end of main switch in AC-DC translation circuits 101；
The signal processing circuit 105 that output end is connected with the input of voltage control loop 104.
In the LED driver that the present embodiment is provided, AC-DC translation circuits 101 are isolated form topology, AC-DC conversion
The first vice-side winding 111 in circuit 101 is connected with the first rectification module 112, the output end conduct of the first rectification module 112
The output end 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 output end 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 output end of current regulator 103；Main switch Q cold end is
The negative terminal of the input of BUCK circuits 102；
The first diode D1 that anode is connected with main switch Q hot end；First diode D1 negative electrode connection
The anode of the input of BUCK circuits 102 and the anode of output end；
The inductance L that one end is connected with the first diode D1 anode；The inductance L other end is the output end of BUCK circuits 102
Negative terminal.
When main switch Q hot end 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.
It is preferred that, as shown in figure 3, the input of voltage control loop 104 is connected with the output end of signal processing circuit 105.
The input of signal processing circuit 105 is connected with the input and output end of BUCK circuits 102, for detecting BUCK circuits 102
Input voltage Vs and output voltage V2 difference.
When AC-DC translation circuits 101 are that isolated form is topological, the input voltage Vs of BUCK circuits 102 converts electricity using AC-DC
The output voltage of the output voltage, now the first rectification module 112 and the second rectification module 114 of the rectification module 114 of road 101 second
Proportional, then the output voltage V1 of input voltage Vs and the AC-DC translation circuit 101 of BUCK circuits 102 is also into this ratio,
Such as Vs/V1=A (wherein A is coefficient)；Now signal processing circuit 105 is designed to detect the input voltage of BUCK circuits 102
Difference Vd=A × V1-V2=Vs-V2 of Vs and output voltage V2 signal, so the input design of signal processing circuit 105
It is connected for the input and output end respectively with BUCK circuits 102.
Fig. 4 show the defeated of output voltage V1, BUCK circuit 102 of LED load voltage Vled, AC-DC translation circuit 101
Go out voltage V2, and BUCK circuits 102 input voltage Vs and output voltage V2 signal difference Vd oscillogram, current control
Ring 103, which controls constant current output, i.e. LED load, does not have current ripples, just without voltage ripple yet, that is to say, that LED load electricity
It is the DC quantity without ripple, and Vled=V1+V2 to press Vled.Because of difference Vd=A × V1-V2=Vs-V2, so difference Vd
Ripple is very big, is twice of the output voltage V1 ripples of AC-DC translation circuits 101, as shown in Figure 4；If difference Vd is directly defeated
Enter voltage control loop 104 and may result in that voltage control loop loop dynamic response speed is slow or PF values are low；It is therefore desirable at signal
Reason circuit 105 carries out input voltage control ring 104 again after peak holding processing or valley holding processing.
The processing of difference Vd peak holdings or valley are kept being processed as low ripple difference signal by signal processing circuit 105 again
After Vd1, low ripple difference signal Vd1 is compared with a reference value Vref by voltage control loop 104, AC- is controlled according to comparative result
The main switch of DC translation circuits 101, makes to meet simultaneously：V1+Vin >=Vo, with V2 >=0.5 × V11；By V2 >=0.5 × V11,
It can ensure that the output voltage of BUCK circuits 102 is completely counterbalanced by all ripples point on the output voltage of AC-DC translation circuits 101
Amount, makes ripple current in the LED load close to zero；And because of the antihypertensive effect of BUCK circuits 102, be by V1+Vin >=Vo
It can ensure in the range of all load voltages, BUCK circuits 102 can normal closed loop work.
It is preferred that, as shown in figure 5, signal processing circuit 105 includes：
The second diode D2 that anode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity C that one end is connected with the second diode D2 negative electrode；The electric capacity C other end and the BUCK circuit input ends
Negative terminal be connected；
It is parallel to the resistance R at electric capacity C two ends；Second diode D2 negative electrode and electric capacity C and resistance R tie point with it is described
The input of voltage control loop is connected.
Or, as shown in fig. 6, signal processing circuit 105 includes：
The second diode D2 that anode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity C that one end is connected with the second diode D2 negative electrode；The electric capacity C other end and the BUCK circuit input ends
Negative terminal be connected；
The first resistor R1 and second resistance R2 being connected in series；The first resistor R1 and the second resistance R2 connection
Point is connected with the input of the voltage control loop；The negative electrode of the other end of the first resistor R1 and the second diode D2
And the tie point of the electric capacity C is connected；The second resistance R2 other end and the negative terminal of electric capacity C and the BUCK circuit input ends
Tie point is connected.
When signal processing circuit 105 is when implementing form for shown in Fig. 5, low ripple difference signal Vd1 and difference Vd
Maximum voltage it is equal, simply ripple reduces, low ripple difference signal Vd1 as shown in Figure 7 and difference Vd oscillogram, by scheming
7 is visible, and ripples of the low ripple difference signal Vd1 than difference Vd is small.
Signal processing circuit 105 shown in Fig. 6 is implemented from unlike Fig. 5, due to the partial pressure with resistance, making
Low ripple difference signal Vd1 is more than ripple reduction, and its maximum voltage is also below difference Vd.
It is preferred that, as shown in figure 8, signal processing circuit 105 also includes：
The 3rd resistor R3 and first switch K1 being connected in series；The 3rd resistor R3 other end is connected with electric capacity C one end,
The first switch K1 other end is connected with the electric capacity C other end.
Shown in Fig. 8, the lower first switch K1 closures of heavy duty.Under underloading, first switch K1 disconnects.Because LED load is in underloading
When ripple amplitude higher than heavy duty when ripple amplitude, therefore control first switch K1 to disconnect in underloading, the equivalent of electric capacity C is put
Resistance increases, and the velocity of discharge slows down；More conducively reduce ripple.
It is preferred that, as shown in figure 9, signal processing circuit 105 also includes：
It is connected to the 4th resistance R4 between electric capacity C and first resistor R1；
The second switch K2 being connected in parallel with the 4th resistance R4.
Shown in Fig. 9, under heavy duty, second switch K2 closures.Under underloading, second switch K2 disconnects.Because LED load is in underloading
When ripple amplitude higher than heavy duty when ripple amplitude, therefore control second switch K2 to disconnect in underloading, the equivalent of electric capacity C is put
Resistance increases, and the velocity of discharge slows down；More conducively reduce ripple.
It is preferred that, as shown in Figure 10, signal processing circuit 105 also includes：
The comparator U that output end is connected with the second diode D2 anode；Comparator U in-phase input end and the BUCK
The negative terminal of circuit output end is connected, and comparator U inverting input is connected with the second diode D2 negative electrode.
Figure 10 is another embodiment that peak holding processing is realized in signal processing circuit 105, and shown in Fig. 5 and Fig. 6
The operation principle of embodiment is similar, namely similar with the principle for how realizing peak holding, and here is omitted.Unlike,
In specific application, the low ripple difference signal Vd1 and difference Vd of output peak value is not complete for embodiment shown in Fig. 5 and Fig. 6
It is complete equal, but the peak value than difference Vd is small, the difference between low ripple difference signal Vd1 and difference Vd is the second diode D2
Pressure drop.
And the signal processing circuit 105 described in the present embodiment, in the absence of above mentioned problem, the low ripple difference signal of output
Vd1 is equal with difference Vd peak value.
It is preferred that, as shown in figure 11, signal processing circuit 105 includes：
The second diode D2 that negative electrode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity C that one end is connected with the second diode D2 anode；The electric capacity C other end and the BUCK circuit input ends
Negative terminal be connected；
It is parallel to the resistance at the second diode D2 two ends；Second diode D2 anode and electric capacity C and resistance R tie point
It is connected with the input of the voltage control loop.
Signal processing circuit 105 in Fig. 5, Fig. 6, Fig. 8, Fig. 9, and embodiment shown in Figure 10 can be achieved peak value and protect
Hold processing；And the signal processing circuit 105 in the present embodiment is accomplished that valley is kept, from unlike peak holding, inputting
As shown in figure 12, the valley of the Vd1 after processing is equal with original input signal Vd valley for the oscillogram of signal and output signal.
And Fig. 5 and Fig. 6 signal processing circuit 105 realizes that the signal Vd1 after peak holding processing is equal with original signal Vd peak value, such as
Shown in Fig. 7.
It is preferred that, as shown in figure 13, signal processing circuit 105 also includes：
The comparator U that output end is connected with the second diode D2 negative electrode；Comparator U in-phase input end and the BUCK
The negative terminal of circuit output end is connected, and comparator U inverting input is connected with the second diode D2 anode.
Figure 13 is realizes that valley keeps another embodiment of processing in signal processing circuit 105, with the implementation shown in Figure 11
The operation principle of example is similar, and here is omitted.Unlike, the signal processing circuit 105 described in the present embodiment, output it is low
Ripple difference signal Vd1 is equal with difference Vd valley.
It is preferred that, a reference value Vref in voltage control loop 104 is with the LED load voltage non-monotonic decreasing.
For example, a reference value Vref of voltage control loop 104 can be taken with the LED load voltage monotonic increase.That is,
Raise, reduced with the reduction a reference value of the LED load voltage with the rise a reference value of the LED load voltage.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 to be controlled as constant current value by current regulator 103, therefore, when a reference value Vref is monotonically changed with the LED load voltage
When, it is ensured that the power 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 14, including：
The AC-DC translation circuits 101 and BUCK circuits 102 of output end series connection；
The current regulator 103 that output end is connected with the control end of main switch Q pipes in BUCK circuits 102；
The voltage control loop 104 that output end is connected with the control end of main switch in AC-DC translation circuits 101；
The signal processing circuit 105 that output end is connected with the input of voltage control loop 104.
The LED driver that the present embodiment is provided also includes：Load voltage difference circuit 106, 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.
It is preferred that, BUCK circuits 102 include：
The main switch Q that control end is connected with the output end of current regulator 103；Main switch Q ground potential end is
The negative terminal of the input of BUCK circuits 102；
The first diode D that anode is connected with main switch Q hot end；First diode D negative electrode connection BUCK
The anode of the input of circuit 102 and the anode of output end；
The inductance L that one end is connected with the first diode D anode；The inductance L other end is the output end of BUCK circuits 102
Negative terminal.
It is preferred that, AC-DC translation circuits 101 are the first vice-side winding in isolated form topology, AC-DC translation circuits 101
111 are connected with the first rectification module 112, the output end of the first rectification module 112 as AC-DC translation circuits 101 output end；
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 with the input of BUCK circuits 102 to be connected.
A reference value Vref amplitude is passed with the amplitude dullness of the LED load voltage Vo in embodiment shown in Figure 14
Increase.Due to voltage control loop 104 reference ground for BUCK circuits 102 input voltage Vs input negative terminal；Specific
In, the reference ground of amplifier and difference Vd reference ground can also be the input of BUCK circuits 102 in voltage control loop 104
The negative terminal of voltage Vs input, so a reference value Vref reference ground should also be the input voltage Vs's of BUCK circuits 102
The negative terminal of input.And the negative terminal of the input voltage Vs of BUCK circuits 102 input and load voltage Vo are not altogether, therefore,
Load voltage difference circuit 106 is needed to be converted to the LED load voltage Vo with the defeated of the input voltage Vs of BUCK circuits 102
The negative terminal for entering end is the voltage of reference ground.
It is preferred that, as shown in figure 15, a reference value Vref in voltage control loop 104 is passed with the LED load voltage dullness
During increasing, the input voltage Vs of sampling BUCK circuits 102, and it regard sampled signal as a reference value Vref.
Figure 14 and Figure 15 is a kind of a reference value Vref value mode, can be according to reality in specific practical application
Border situation is selected, and is not specifically limited herein.
It is preferred that, 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.
The embodiment of each in the present invention 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, because it is corresponded to the method disclosed in Example, so description is fairly simple, related part is referring to method part illustration
.
It the above is only the preferred embodiment of the present invention, make skilled artisans appreciate that or realizing of the invention.It is right
A variety of modifications of these embodiments will be apparent to one skilled in the art, general original as defined herein
Reason can be realized in other embodiments without departing from the spirit or scope of the present invention.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 (14)
1. a kind of LED driver, it is characterised in that including：
The AC-DC translation circuits and BUCK circuits of output end series connection, the AC-DC translation circuits and BUCK circuits are provided commonly for driving
Dynamic LED load；
The current regulator that output end is connected with the control end of main switch in the BUCK circuits, is flowed through described for detection
The electric current of LED load, and compared with a reference signal, the main switch of the BUCK circuits is controlled according to comparative result, makes institute
State the output of LED driver current stabilization；
Signal processing circuit, for detect characterize AC-DC translation circuits output voltage signal and the BUCK circuits it is defeated
Go out the difference signal of the signal of voltage, and to exporting low after difference signal progress peak holding processing or valley holding processing
Ripple difference signal；
The voltage control loop that output end is connected with the control end of main switch in the AC-DC translation circuits, the voltage control
The input of ring is connected with the output end of the signal processing circuit, for receiving the low ripple difference signal, and and benchmark
Value compares, and the main switch of the AC-DC translation circuits is controlled according to comparative result, makes the output of the AC-DC translation circuits
The input voltage sum of voltage and the BUCK circuits is more than or is instantaneously equal to the LED load voltage, and makes the BUCK
The output voltage average value of circuit is more than or equal to the half of 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 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 output end of first rectification module
It is used as the output end 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 output end 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 output end of the current regulator；The cold end of the main switch is described
The negative terminal of BUCK circuit input ends；
The first diode that anode is connected with the hot end of the main switch；The negative electrode connection of first diode is described
The anode of BUCK circuit input ends and the anode of output end；
The inductance that one end is connected with the anode of first diode；The other end of the inductance is the BUCK circuit output ends
Negative terminal.
4. LED driver according to claim 1, it is characterised in that the signal processing circuit includes：
The second diode that anode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity that one end is connected with the negative electrode of second diode；The other end of the electric capacity and the BUCK circuit input ends
Negative terminal be connected；
It is parallel to the resistance at the electric capacity two ends；The negative electrode of second diode and the electric capacity and the tie point of the resistance
It is connected with the input of the voltage control loop.
5. LED driver according to claim 1, it is characterised in that the signal processing circuit includes：
The second diode that anode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity that one end is connected with the negative electrode of second diode；The other end of the electric capacity and the BUCK circuit input ends
Negative terminal be connected；
The first resistor and second resistance being connected in series；The tie point of the first resistor and the second resistance and the voltage
The input of control ring is connected；The connection of the other end of the first resistor and the negative electrode and the electric capacity of second diode
Point is connected；The other end of the second resistance is connected with the tie point of the electric capacity and the negative terminal of the BUCK circuit input ends.
6. LED driver according to claim 5, it is characterised in that the signal processing circuit also includes：
The 3rd resistor and first switch being connected in series；The other end of the 3rd resistor is connected with one end of the electric capacity, institute
The other end for stating first switch is connected with the other end of the electric capacity；The first switch is used to turn under heavy loads, in underloading
Lower shut-off.
7. LED driver according to claim 5, it is characterised in that the signal processing circuit also includes：
It is connected to the 4th resistance between the electric capacity and the first resistor；
The second switch being connected with the 4th resistor coupled in parallel, for turning under heavy loads, is turned off under underloading.
8. the LED driver according to claim 4 or 5, it is characterised in that the signal processing circuit also includes：
It is connected to the comparator between the anode of the negative terminal of the BUCK circuit output ends and second diode；The comparison
The output end of device is connected with the anode of second diode；The in-phase input end of the comparator and the BUCK circuit outputs
The negative terminal at end is connected, and the inverting input of the comparator is connected with the negative electrode of second diode.
9. LED driver according to claim 1, it is characterised in that the signal processing circuit includes：
The second diode that negative electrode is connected with the negative terminal of the BUCK circuit output ends；
The electric capacity that one end is connected with the anode of second diode；The other end of the electric capacity and the BUCK circuit input ends
Negative terminal be connected；
It is parallel to the resistance at the second diode two ends；The anode of second diode and the electric capacity and the resistance
Tie point is connected with the input of the voltage control loop.
10. LED driver according to claim 9, it is characterised in that the signal processing circuit also includes：
It is connected to the comparator between the negative electrode of the negative terminal of the BUCK circuit output ends and second diode；The comparison
The output end of device is connected with the negative electrode of second diode；The in-phase input end of the comparator and the BUCK circuit outputs
The negative terminal at end is connected, and the inverting input of the comparator is connected with the anode of second diode.
11. LED driver according to claim 1, it is characterised in that a reference value in the voltage control loop with
The LED load voltage monotonic increase.
12. LED driver according to claim 11, it is characterised in that also include：Load voltage difference circuit, is used for
The LED load voltage is detected, and is reference ground and the reference ground phase of the voltage control loop by the LED load voltage conversion
Same voltage.
13. the LED driver according to claim 3 or 11, it is characterised in that the benchmark in the voltage control loop
When value is with the LED load voltage monotonic increase, the input voltage for the BUCK circuits of sampling, and using sampled signal as described
A reference value.
14. LED driver according to claim 1, it is characterised in that main switch in the BUCK circuits with it is described
Current regulator is arranged in same integrated circuit.
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| CN104993692B (en) * | 2015-08-07 | 2017-07-14 | 英飞特电子（杭州）股份有限公司 | A kind of pfc circuit |
| CN105958825B (en) * | 2016-06-07 | 2019-04-02 | 英飞特电子（杭州）股份有限公司 | A kind of primary current control driving circuit |
| CN106793255A (en) * | 2016-11-29 | 2017-05-31 | 广西大学 | A kind of new explosion-proof mining locomotive illuminating lamp |
| CN108152561A (en) * | 2018-03-14 | 2018-06-12 | 广东海明晖电子科技有限公司 | Igh-speed wire-rod production line circuit |
| WO2022041873A1 (en) * | 2020-08-24 | 2022-03-03 | 海信视像科技股份有限公司 | Display apparatus and step power circuit |
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| KR100950913B1 (en) * | 2007-11-29 | 2010-04-01 | 삼성전기주식회사 | DC/DC Converter |
| 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 |
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