CN105792437B - A kind of LED drive circuit - Google Patents
A kind of LED drive circuit Download PDFInfo
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- CN105792437B CN105792437B CN201610262294.4A CN201610262294A CN105792437B CN 105792437 B CN105792437 B CN 105792437B CN 201610262294 A CN201610262294 A CN 201610262294A CN 105792437 B CN105792437 B CN 105792437B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/40—Details of LED load circuits
- H05B45/44—Details of LED load circuits with an active control inside an LED matrix
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
- H05B45/14—Controlling the intensity of the light using electrical feedback from LEDs or from LED modules
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Abstract
The application provides a kind of LED drive circuit, and LED load is driven jointly by the concatenated non-isolation DC of output end/DC converter units and steady flow unit；By Voltage loop control unit according to the sampled signal VS of characterization non-isolation DC/DC converter unit output voltages V2, with the relevant feedback signal VFB of output ripple of the steady flow unit and with the positively related DC reference signal Vref of size of the output ripple, control the opposite in phase of the output voltage ripple of non-isolation DC/DC converter units and the output voltage ripple of steady flow unit, and make the output voltage average value of non-isolation DC/DC converter units follow steady flow unit output ripple size and change, and then so that the ripple in LED load is reduced and even be eliminated, avoid output current that there is larger ripple and LED light is caused stroboscopic phenomenon occur, and ensure circuit stability and efficiency optimization.
Description
Technical field
The present invention relates to field of LED drive technology more particularly to a kind of LED drive circuits.
Background technology
LED is widely used in lighting area as a kind of novel illumination device due to its luminous efficiency height, and it is logical
Often constant current is needed to drive, in the prior art as the LED driver of its current stabilization driving in order to which cost of implementation is cheap and structure letter
Single characteristic, 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 needs very slow response speed that can just have higher PF (Power Factor, work(
Rate factor) value, therefore, control loop response speed is slower, and this can cause output current to have larger ripple, the ripple
Period be the input ac voltage period half.When LED driver is connected and loaded, this current ripples will lead to LED light
There is stroboscopic phenomenon, this stroboscopic phenomenon will influence the service life of LED light, also there is certain damage to human eye.
Invention content
In view of this, the present invention provides a kind of LED drive circuit, to solve prior art output current with larger
Ripple and cause LED light the problem of stroboscopic phenomenon occur.
To achieve the goals above, technical solution provided in an embodiment of the present invention is as follows：
A kind of LED drive circuit, including：
Steady flow unit, the current value stable for controlling the LED drive circuit output；
The concatenated non-isolation DC of output end/DC converter units of output end and the steady flow unit, the steady flow unit and
The non-isolation DC/DC converter units are provided commonly for driving LED load；
The feedback signal acquiring unit that input terminal is connected with the output end of the steady flow unit；The feedback signal obtains single
Output ripple of the member for obtaining the steady flow unit, and it is relevant anti-with the output ripple according to output ripple generation
Feedback signal；The output ripple includes：Output current ripple and/or the output voltage ripple；
DC reference acquiring unit, the DC reference acquiring unit is for generating and the size positive of the output ripple
The DC reference signal of pass；
Two input terminals respectively with the output end of the DC reference acquiring unit and the feedback signal acquiring unit
The connected Voltage loop control unit of output end；The output end of the Voltage loop control unit and the non-isolation DC/DC transformation are single
The control terminal of member is connected；The Voltage loop control unit is for obtaining a characterization non-isolation DC/DC converter units output
The sampled signal of voltage, and the feedback signal and the DC reference signal are received, become for controlling the non-isolation DC/DC
The output voltage for changing unit makes output voltage ripple and the institute of the non-isolation DC/DC converter units according to the feedback signal
The opposite in phase of the output voltage ripple of steady flow unit is stated, and so that the non-isolation DC/DC is become according to the DC reference signal
The output voltage average value for changing unit follows the size of the output ripple and changes.
Preferably, the feedback signal acquiring unit includes：Block isolating circuit；The input terminal of the block isolating circuit with it is described steady
The output end for flowing unit is connected, and the output end of the block isolating circuit is connected with the input terminal of the Voltage loop control unit.
Preferably, the feedback signal acquiring unit includes：Difference channel and block isolating circuit；Wherein：
Two input terminals of the difference channel are connected with two output ends of the steady flow unit respectively, the differential electrical
Road is used to obtain the output parameter of the steady flow unit；
The input terminal of the block isolating circuit is connected with the output end of the difference channel, and the block isolating circuit is used for according to institute
State output parameter obtain with the relevant feedback signal of the steady flow unit output ripple, and the feedback signal is input to
The Voltage loop control unit.
Preferably, the DC reference acquiring unit includes：Acquisition feedback signal maximum value is the DC reference signal
Maximum value circuit；The input terminal of the maximum value circuit connects the output end of the block isolating circuit, the maximum value circuit
Output end is the output end of the DC reference acquiring unit.
Preferably, the DC reference acquiring unit includes：The DC reference signal is set to vary with temperature and reversely become
The temperature sensing circuit of change.
Preferably, the steady flow unit is isolated form topology, and the steady flow unit includes：Primary side winding, the first secondary side around
Group, the first rectification module, first resistor and first switch pipe；Wherein：
The output end of first vice-side winding is connected with the input terminal of first rectification module；
The output end of first rectification module is the output end of the steady flow unit；
The different name end of the primary side winding is an input terminal of the steady flow unit；
The Same Name of Ends of the primary side winding passes sequentially through the first switch pipe and connects the current stabilization with the first resistor
Another input terminal of unit；
The control terminal of the first switch pipe receives drive signal.
Preferably, the steady flow unit further includes：Second vice-side winding and the second rectification module；Second vice-side winding
Output end be connected with the input terminal of second rectification module；The output end of second rectification module with it is described non-isolated
The input terminal of DC/DC converter units is connected.
Preferably, the Voltage loop control unit includes：Adder and the first integrated transporting discharging；One of the adder is defeated
Enter end and receive the DC reference signal, another input terminal of the adder receives the feedback signal；The adder
Output end is connected with an input terminal of first integrated transporting discharging；Another input terminal of first integrated transporting discharging receives institute
State sampled signal；
Alternatively, the Voltage loop control unit includes：Subtracter and the second integrated transporting discharging；One input of the subtracter
End receives the feedback signal；Another input terminal of the subtracter receives the sampled signal；The output of the subtracter
End is connected with an input terminal of second integrated transporting discharging；Another input terminal of second integrated transporting discharging receives described straight
Flow reference signal；
Wherein, the feedback signal and the output ripple opposite in phase.
Preferably, the Voltage loop control unit includes：Subtracter and the first integrated transporting discharging；One of the subtracter is defeated
Enter end and receive the DC reference signal, another input terminal of the subtracter receives the feedback signal；The subtracter
Output end is connected with an input terminal of first integrated transporting discharging；Another input terminal of first integrated transporting discharging receives institute
State sampled signal；
Alternatively, the Voltage loop control unit includes：Adder and the second integrated transporting discharging；One input of the adder
End receives the feedback signal；Another input terminal of the adder receives the sampled signal；The output of the adder
End is connected with an input terminal of second integrated transporting discharging；Another input terminal of second integrated transporting discharging receives described straight
Flow reference signal；
Wherein, the feedback signal is identical as the output ripple phase.
Preferably, further include dimming control unit, the dimming control unit output dim signal to the steady flow unit,
The output current of the steady flow unit is set to change.
The application provides a kind of LED drive circuit, and the stable electricity of the LED drive circuit output is controlled by steady flow unit
Flow valuve；LED load is driven jointly by the concatenated non-isolation DC of output end/DC converter units and the steady flow unit；By anti-
Feedback signal acquiring unit obtains the output ripple of the steady flow unit, and generates the output ripple according to the output ripple
Feedback signal VFB；Then the positively related DC reference of size with the output ripple is generated by DC reference acquiring unit
Signal Vref；Finally one is obtained by Voltage loop control unit characterize the non-isolation DC/DC converter unit output voltages V2's
Sampled signal VS, and receive feedback signal VFB and DC reference signal Vref, according to sampled signal VS controls it is described it is non-every
The opposite in phase of output voltage ripple and the output voltage ripple of the steady flow unit from DC/DC converter units, and according to straight
Flow the size that reference signal Vref makes the output voltage average value of the non-isolation DC/DC converter units follow the output ripple
And change, make the output voltage ripple of the non-isolation DC/DC converter units with the output voltage ripple phase of the steady flow unit
It offsets, and then so that the ripple in LED load is reduced and even be eliminated, avoid output current that there is larger ripple and cause LED light
There is stroboscopic phenomenon.
Description of the drawings
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technology description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
The embodiment of invention for those of ordinary skill in the art without creative efforts, can also basis
The attached drawing of offer obtains other attached drawings.
Fig. 1 is a kind of structural schematic diagram of LED drive circuit provided by the embodiments of the present application；
Fig. 2 is a kind of signal waveform schematic diagram that another embodiment of the application provides；
Fig. 3 is another signal waveform schematic diagram that another embodiment of the application provides；
Fig. 4 is a kind of structural schematic diagram for LED drive circuit that another embodiment of the application provides；
Fig. 5 is the structural schematic diagram for another LED drive circuit that another embodiment of the application provides.
Specific implementation mode
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation describes, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
The present invention provides a kind of LED drive circuits, are made with larger ripple with solving prior art output current
There is the problem of stroboscopic phenomenon at LED light.
Specifically, as shown in Figure 1, the LED drive circuit includes：Steady flow unit 101, non-isolation DC/DC converter units
102, feedback signal acquiring unit 103, DC reference acquiring unit 104 and Voltage loop control unit 105；Wherein：
The output end of steady flow unit 101 and non-isolation DC/DC converter units 102 is connected；
The input terminal of feedback signal acquiring unit 103 is connected with the output end of steady flow unit 101；
Two input terminals of Voltage loop control unit 105 respectively with the output end and direct current of feedback signal acquiring unit 103
The output end of benchmark acquiring unit 104 is connected；The output end of Voltage loop control unit 105 and non-isolation DC/DC converter units 102
Control terminal be connected.
It is worth noting that the anode of the output end of steady flow unit 101 is connected with the anode of LED load in Fig. 1, it is non-isolated
The negative terminal of the output end of DC/DC converter units 102 is connected with the cathode of the LED load；In practical applications, it can also use
The anode of output end of non-isolation DC/DC converter units 102 is connected with the anode of LED load, the output end of steady flow unit 101
Negative terminal is connected with the cathode of the LED load；Fig. 1 is only a kind of example, steady flow unit 101 and non-isolation DC/DC converter units
102 with the connection type of the LED load and be not specifically limited, can be depending on its actual application environment.
Specifically operation principle is：
Steady flow unit 101 controls the stable current value of the LED drive circuit output；
Non-isolation DC/DC converter units 102 drive LED load jointly with steady flow unit 101；
Feedback signal acquiring unit 103 obtain steady flow unit 101 output ripple, and according to the output ripple generate with
The relevant feedback signal VFB of output ripple；
Optionally, the output ripple includes：Output current ripple and/or output voltage ripple.
DC reference acquiring unit 104 generates the positively related DC reference signal Vref of size with the output ripple；
Voltage loop control unit 105 obtains the sampling letter of a 102 output voltage V2 of characterization non-isolation DC/DC converter units
Number VS, and feedback signal VFB and DC reference signal Vref are received, non-isolation DC/DC converter units are made according to sampled signal VS
The opposite in phase of 102 output voltage ripple and the output voltage ripple of steady flow unit 101, and according to DC reference signal Vref
The output voltage average value of non-isolation DC/DC converter units 102 is set to follow the size of the output ripple of steady flow unit 101 and become
Change.
The LED drive circuit provided by the present application, by above-mentioned connection relation and operation principle, control non-isolation DC/
The opposite in phase of the output voltage ripple of DC converter units 102 and the output voltage ripple of steady flow unit 101, and make non-isolated
The output voltage average value of DC/DC converter units 102 follows the size of the output ripple and changes, and non-isolation DC/DC is made to become
The output voltage ripple for changing unit 102 is offseted with the output voltage ripple of steady flow unit 101, and then makes the line in LED load
Wave reduction even is eliminated, and output current is avoided to have larger ripple and LED light is caused stroboscopic phenomenon occur.
It is worth noting that in the prior art, in order to avoid output current has larger ripple and LED light is caused to occur
Stroboscopic phenomenon, using the LED driver of two-step scheme also by more selection, the input terminal of following stage DC-DC converter is straight
It connects and is connected with the output end of prime AC-DC converter, the prime AC-DC converter is for realizing PFC functions, the rear class
For DC-DC converter for realizing constant current or pressure-keeping functions, the control loop response speed of prime AC-DC converter can be very slow,
Without leading to LED driver output current ripple problem, the control loop response speed of rear class DC-DC converter can be compared with
Soon, meet quickly adjust and reduce output current ripple demand, it is easy to solve the problems, such as that single-stage solution exists.
But two-step scheme is not only complicated, it is of high cost, and since input power has carried out two times transfer, make LED
The efficiency of driver is the efficiency product of two-stage circuit.Such as front stage circuits efficiency is η 1, late-class circuit efficiency is η 2, then existing
Technology is greatly reduced the efficiency of LED driver, is increased damage using efficiency eta=1 × η of η 2 of the LED driver of two-step scheme
Consumption, cannot highlight the energy saving advantage of LED illumination System.
And the LED drive circuit provided in this embodiment is used, by above-mentioned connection type and control principle, without adding
The loop response speed of fast main circuit is come while realizing that low ripple exports, therefore can ensure higher PF values, if current stabilization
The efficiency of unit 101 is η 1, and the efficiency of non-isolation DC/DC converter units 102 is η 2, then the efficiency eta of the LED drive circuit is only
It is slightly less than η 1, degree of the efficiency eta less than η 1 of the LED drive circuit depends on non-isolation DC/DC converter units 102 and handle work(
The size of rate, compared with prior art in it is efficient and be lost low using the LED driver of two-step scheme.
In specific practical application, DC reference signal Vref that DC reference acquiring unit 104 in Fig. 1 generates with
The size positive correlation of the output ripple, in particular to, DC reference signal Vref with 101 output voltage V1 of steady flow unit line
Wave size variation and change in the same direction, i.e. the ripple of 101 output voltage V1 of steady flow unit is bigger, DC reference signal Vref also more
Greatly.
For the output voltage waveforms of the steady flow unit as shown in the V1 in Fig. 2, the feedback signal acquiring unit obtains V1
AC compounent obtain feedback signal VFB, the DC reference acquiring unit generates the size positive with the output ripple
The DC reference signal Vref of pass, the Voltage loop control unit obtain a characterization non-isolation DC/DC converter units output electricity
The sampled signal VS of V2 is pressed, the Voltage loop control unit is exported according to VFB, Vref and VS controls signal, the non-isolation DC/
DC converter units receive the control signal, itself output voltage V2 is made to carry the AC compounent reversed with the AC compounent of V1.
The output voltage Vled=V1+V2 of the obtained LED drive circuit, ripple will reduce.It is described in order to completely eliminate
The size of ripple on the output voltage Vled of LED drive circuit, the AC compounent of V2 should be equal in magnitude with V1 AC compounents,
Direction is opposite.
The setting of feedback signal acquiring unit 103 and DC reference acquiring unit 104 in Fig. 1, be in order to obtain with surely
The reversed signal (Vref-VFB) of the ripple of 101 output voltage V1 of unit is flowed, as shown in Figure 2；101 output voltage V1 of steady flow unit
Peak value correspond to (Vref-VFB) valley；And the comparison signal by (Vref-VFB) as sampled signal VS, Voltage loop control
Unit 105 exports control signal VC according to the comparison result of the two, make the output voltages of non-isolation DC/DC converter units 102 with
101 output voltage V1 of steady flow unit is equal in magnitude, and direction is on the contrary, eliminate the ripple in LED load with this.
Oscillogram as shown in Figure 3, in order to completely eliminate the LED drive circuit output voltage Vled ripple, directly
Stream reference signal Vref should be greater than the half equal to V1 ripple peak-to-peak values, and otherwise, continuous 0 value will occur in (Vref-VFB), described
Ripple on the output voltage Vled of LED drive circuit cannot be completely eliminated；Also, the value of DC reference signal Vref follows
It the variation of V1 ripples and changes, V1 ripples increase (V1 ' as shown in Figure 3), then Vref increases (as shown in Figure 3
Vref '), (Vref-VFB) will also increase, (Vref '-VFB ') as shown in Figure 3；Conversely, V1 ripples reduce, Vref reduces.
Because the energy (DC voltage) that LED load is obtained from the non-isolation DC/DC converter units have passed through described steady
Unit and the non-isolation DC/DC converter unit two-stage circuits are flowed, efficiency is less than the efficiency merely through the steady flow unit, institute
Changed with the variation of the output voltage V1 ripples of the steady flow unit so that DC reference signal Vref is arranged, not only be can guarantee
The effect of ripple is dropped, and circuit efficiency can be improved.So most preferably, setting DC reference signal Vref is equal to described steady
The half of the output voltage V1 ripple peak-to-peak values of unit is flowed, or is stablized for holding circuit, its half is slightly larger than.It does not do and has herein
Body limits, within the scope of protection of this application.
In another embodiment, the sampling letter of the non-isolation DC/DC converter unit output voltages V2 is characterized
Number VS is directly obtained from the output end of the non-isolation DC/DC converter units, as shown in Figure 4.
Preferably, as shown in figure 4, the steady flow unit is isolated form topology, the steady flow unit includes：Primary side winding,
First vice-side winding 401, the first rectification module, first resistor R1 and first switch pipe K1；Wherein：
The output end of first vice-side winding 401 is connected with the input terminal of first rectification module；
The output end of first rectification module is the output end of the steady flow unit；
The different name end of the primary side winding is an input terminal of the steady flow unit；
The Same Name of Ends of the primary side winding passes sequentially through first switch pipe K1 and first resistor R1 and is connected to the current stabilization list
Another input terminal of member；
The control terminal of first switch pipe K1 receives drive signal；The drive signal, which controls the steady flow unit and realizes, to be stablized
Electric current output.
Preferably, the drive signal is to control the steady flow unit according to the steady flow unit primary current sampled signal
The signal of current stabilization output.
Preferably, the primary current is obtained by first resistor R1 samplings.
Preferably, as shown in figure 4, the steady flow unit further includes：Second vice-side winding 402 and the second rectification module；The
The output end of two vice-side windings 402 is connected with the input terminal of second rectification module；The output end of second rectification module
It is connected with the input terminal of the non-isolation DC/DC converter units.
Referring to Fig. 4, when the steady flow unit is isolated form topology, the input voltage of the non-isolation DC/DC converter units
Vin is the voltage after the second vice-side winding of transformer 402 of the steady flow unit is rectified.
Preferably, as shown in figure 4, the feedback signal acquiring unit includes：Block isolating circuit；The input of the block isolating circuit
End connects the output end of the steady flow unit, the input terminal phase of the output end of the block isolating circuit and the Voltage loop control unit
Even.
The steady flow unit shown in Fig. 4 and the feedback signal acquiring unit are only a kind of example, might not be limited
It, can be depending on its specific application environment in this.
In another embodiment of the present invention, as shown in figure 4, the DC reference acquiring unit includes：Make direct current base
Calibration signal Vref is varied with temperature and the temperature sensing circuit of inverse change.
Since temperature is lower, the output electrolytic capacitor ESR of the steady flow unit and shown non-isolation DC/DC converter units increases
Greatly, ripple increases.Therefore the DC reference acquiring unit includes the temperature sensing circuit, can make to be input to the voltage
The DC reference signal Vref of ring control unit changes with temperature change, and temperature increases, and DC reference signal Vref reduces；
Temperature reduces, and DC reference signal Vref is increased.Avoid influence of the temperature for output ripple；Ensure different temperatures under have compared with
Good drop ripple effect, while also can guarantee circuit stability and efficiency optimization.
Optionally, the Voltage loop control unit includes：Subtracter and the first integrated transporting discharging；One of the subtracter is defeated
Enter end and receive DC reference signal Vref, another input terminal of the subtracter receives feedback signal VFB；The subtracter it is defeated
Outlet is connected with an input terminal of first integrated transporting discharging；Another input terminal of first integrated transporting discharging receives sampling
Signal VS；
Alternatively, the Voltage loop control unit includes：Adder and the second integrated transporting discharging；One input of the adder
End receives feedback signal VFB；Another input terminal of the adder receives sampled signal VS；The output end of the adder with
One input terminal of second integrated transporting discharging is connected；Another input terminal of second integrated transporting discharging receives DC reference letter
Number Vref；
The wherein described feedback signal is identical as the output ripple phase.
Alternatively, optional, the Voltage loop control unit includes：Adder and the first integrated transporting discharging；The adder
One input terminal receives the DC reference signal, and another input terminal of the adder receives the feedback signal；It is described to add
The output end of musical instruments used in a Buddhist or Taoist mass is connected with an input terminal of first integrated transporting discharging；Another input terminal of first integrated transporting discharging
Receive the sampled signal；
Alternatively, the Voltage loop control unit includes：Subtracter and the second integrated transporting discharging；One input of the subtracter
End receives the feedback signal；Another input terminal of the subtracter receives the sampled signal；The output of the subtracter
End is connected with an input terminal of second integrated transporting discharging；Another input terminal of second integrated transporting discharging receives described straight
Flow reference signal；
Wherein, the feedback signal and the output ripple opposite in phase.
The effect of the block isolating circuit is that the AC compounent for the output voltage V1 for obtaining the steady flow unit obtains feedback letter
Number VFB, and it is input to the Voltage loop control unit；DC reference signal Vref and feedback signal VFB is used as sampling after subtracting each other
The reference signal of signal VS, VS and (Vref-VFB) export the control signal more afterwards；Or VS be superimposed with VFB after with Vref
Compare the output control signal.It is not specifically limited herein, within the scope of protection of this application.
In another embodiment, the sampling letter of the characterization non-isolation DC/DC converter unit output voltages V2
Number VS is directly obtained from the output end of the non-isolation DC/DC converter units, as shown in Figure 5.
Preferably, as shown in figure 5, the steady flow unit includes：Primary side winding, the first vice-side winding 401, first switch pipe
K1, first resistor R1, the first diode D1 and the first capacitance C1；Wherein：
The anode of first diode D1 is connected with the Same Name of Ends of the first vice-side winding 401；
The cathode of first diode D1 is connected with one end of the first capacitance C1；
The other end of first capacitance C1 is connected with the different name end of the first vice-side winding 401；
The both ends of first capacitance C1 are respectively two output ends of the steady flow unit；
The different name end of the primary side winding is an input terminal of the steady flow unit；
The Same Name of Ends of the primary side winding passes sequentially through first switch pipe K1 and connects the steady flow unit with first resistor R1
Another input terminal；
The control terminal of first switch pipe K1 receives drive signal；.
Preferably, as shown in figure 5, the non-isolation DC/DC converter units are buck circuits；The non-isolation DC/DC becomes
Changing unit includes：Second switch pipe K2, the second diode D2 and the first inductance L1；Wherein：
The input terminal of second switch pipe K2 is an input terminal of the non-isolation DC/DC converter units；
The output end of second switch pipe K2 is connected with one end of the cathode of the second diode D2 and the first inductance L1；
The anode of second diode D2 is another input terminal of the non-isolation DC/DC converter units；
The anode of the other end of first inductance L1 and the second diode D2 are respectively the non-isolation DC/DC converter units
Two output ends.
The input terminal of the non-isolation DC/DC converter units receives input voltage vin, in the non-isolation DC/DC transformation
The output end parallel connection high-frequency filter capacitor (i.e. the second capacitance C2) of unit makes to be free of high fdrequency component in the electric current of the LED load.
Preferably, as shown in figure 5, feedback signal acquiring unit 103 includes：Difference channel and block isolating circuit；Wherein：
Two input terminals of the difference channel are connected with two output ends of the steady flow unit respectively；
The output end of the difference channel is connected with the input terminal of the block isolating circuit；
The output end of the block isolating circuit obtains single with the input terminal of the Voltage loop control unit and the DC reference
The input terminal of member is connected.
Preferably, as shown in figure 5, DC reference acquiring unit 104 includes：Maximum value circuit；The maximum value circuit
Input terminal is the input terminal of the DC reference acquiring unit, connects the output end of the block isolating circuit, the maximum value circuit
Output end be the DC reference acquiring unit output end, be connected to another input terminal of Voltage loop control unit.
It is DC reference signal that the maximum value circuit, which obtains feedback signal VFB and negates the maximum value of feedback signal VFB,
Vref。
Specifically, feedback signal acquiring unit 103 obtains the current stabilization by the difference channel and the block isolating circuit
The AC compounent of the output voltage V1 of unit；Since the maximum value of AC signal is equivalent to the half of ripple peak-to-peak value, so directly
Connected the maximum value circuit obtain the steady flow unit output voltage V1 AC compounent maximum value, can obtain
The half of the output voltage V1 ripple peak-to-peak values of the steady flow unit：V1 ripples are bigger, then the maximum value is bigger.DC reference
Acquiring unit 104 includes maximum value circuit, and DC reference signal Vref is obtained using maximum value circuit；
In specific practical application, reference signal that can be by (Vref-VFB) as VS is compared control with VS
Second switch pipe K2 make its output voltage V2 AC compounent and V1 AC compounent direction on the contrary, equal in magnitude；Or by VFB
Control second switch pipe K2 is compared with the superposed signal (VS+VFB) of VS with Vref makes the AC compounent of its output voltage V2
AC compounent direction with V1 is on the contrary, equal in magnitude.
Also, difference channel described above is because of problem altogether, if by the negative terminal of 101 output end of steady flow unit
Directly as ground, then do not need the difference channel, but at this time sampled signal VS will respective change, so difference channel is not answered
The protection domain of limitation the application.
It should be noted that because main power circuit is the steady flow unit, i.e., the described LED drive circuit is that current stabilization is defeated
Go out, then LED load size variation, the size of V1 may also change accordingly.
Particularly, the LED drive circuit can also apply under conditions of light modulation, and the LED drive circuit further includes
The output end of dimming control unit, the dimming control unit exports dim signal to the steady flow unit, makes the current stabilization list
The output current size of member changes.Specific dimming mode is similar with the prior art, and the size of V1 also can during light modulation
Respective change, i.e. V1 can change, and variation range is determined by the output voltage range of the steady flow unit.It is used in light modulation
When, because of different size of current, ripple is of different sizes, and setting Vref follows ripple size variation in real time, can guarantee difference
Drop ripple effect under electric current and high efficiency, the circuit also have significant advantageous effect in light modulation is used.
Each embodiment is described by the way of progressive in the present invention, the highlights of each of the examples are with other realities
Apply the difference of example, just to refer each other for identical similar portion between each embodiment.For device disclosed in embodiment
Speech, since it is corresponded to the methods disclosed in the examples, so description is fairly simple, related place 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 the principles and novel features disclosed in this article most
Wide range.
Claims (10)
1. a kind of LED drive circuit, which is characterized in that including：
Steady flow unit, the current value stable for controlling the LED drive circuit output；
The concatenated non-isolation DC of output end/DC converter units of output end and the steady flow unit, the steady flow unit and described
Non-isolation DC/DC converter units are provided commonly for driving LED load；
The feedback signal acquiring unit that input terminal is connected with the output end of the steady flow unit；The feedback signal acquiring unit is used
It is generated and the relevant feedback letter of the output ripple in the output ripple for obtaining the steady flow unit, and according to the output ripple
Number；The output ripple includes：Output current ripple and/or the output voltage ripple；
DC reference acquiring unit, the DC reference acquiring unit are positively related with the size of the output ripple for generating
DC reference signal；
The output with the output end of the DC reference acquiring unit and the feedback signal acquiring unit respectively of two input terminals
The connected Voltage loop control unit in end；The output end of the Voltage loop control unit and the non-isolation DC/DC converter units
Control terminal is connected；The Voltage loop control unit is for obtaining a characterization non-isolation DC/DC converter unit output voltage
Sampled signal, and receive the feedback signal and the DC reference signal, it is single for controlling the non-isolation DC/DC transformation
The output voltage of member, according to the feedback signal make the output voltage ripples of the non-isolation DC/DC converter units with it is described steady
The opposite in phase of the output voltage ripple of unit is flowed, and so that the non-isolation DC/DC is converted list according to the DC reference signal
The output voltage average value of member follows the size of the output ripple and changes.
2. LED drive circuit according to claim 1, which is characterized in that the feedback signal acquiring unit includes：Blocking
Circuit；The input terminal of the block isolating circuit is connected with the output end of the steady flow unit, the output end of the block isolating circuit and institute
The input terminal for stating Voltage loop control unit is connected.
3. LED drive circuit according to claim 1, which is characterized in that the feedback signal acquiring unit includes：Difference
Circuit and block isolating circuit；Wherein：
Two input terminals of the difference channel are connected with two output ends of the steady flow unit respectively, and the difference channel is used
In the output parameter for obtaining the steady flow unit；
The input terminal of the block isolating circuit is connected with the output end of the difference channel, and the block isolating circuit is used for according to described defeated
Go out parameter obtain with the relevant feedback signal of the steady flow unit output ripple, and the feedback signal is input to described
Voltage loop control unit.
4. LED drive circuit according to claim 3, which is characterized in that the DC reference acquiring unit includes：It obtains
Feedback signal maximum value is the maximum value circuit of the DC reference signal；The input terminal connection of the maximum value circuit it is described every
The output end of straight circuit, the output end of the maximum value circuit are the output end of the DC reference acquiring unit.
5. LED drive circuit according to claim 1, which is characterized in that the DC reference acquiring unit includes：Make institute
DC reference signal is stated to vary with temperature and the temperature sensing circuit of inverse change.
6. LED drive circuit according to claim 1, which is characterized in that the steady flow unit is isolated form topology, described
Steady flow unit includes：Primary side winding, the first vice-side winding, the first rectification module, first resistor and first switch pipe；Wherein：
The output end of first vice-side winding is connected with the input terminal of first rectification module；
The output end of first rectification module is the output end of the steady flow unit；
The different name end of the primary side winding is an input terminal of the steady flow unit；
The Same Name of Ends of the primary side winding passes sequentially through the first switch pipe and connects the steady flow unit with the first resistor
Another input terminal；
The control terminal of the first switch pipe receives drive signal.
7. LED drive circuit according to claim 6, which is characterized in that the steady flow unit further includes：Second secondary side around
Group and the second rectification module；The output end of second vice-side winding is connected with the input terminal of second rectification module；It is described
The output end of second rectification module is connected with the input terminal of the non-isolation DC/DC converter units.
8. LED drive circuit according to claim 1, which is characterized in that the Voltage loop control unit includes：Adder
With the first integrated transporting discharging；One input terminal of the adder receives the DC reference signal, the adder it is another defeated
Enter end and receives the feedback signal；The output end of the adder is connected with an input terminal of first integrated transporting discharging；Institute
Another input terminal for stating the first integrated transporting discharging receives the sampled signal；
Alternatively, the Voltage loop control unit includes：Subtracter and the second integrated transporting discharging；One input termination of the subtracter
Receive the feedback signal；Another input terminal of the subtracter receives the sampled signal；The output end of the subtracter with
One input terminal of second integrated transporting discharging is connected；Another input terminal of second integrated transporting discharging receives the direct current base
Calibration signal；
Wherein, the feedback signal and the output ripple opposite in phase.
9. LED drive circuit according to claim 1, which is characterized in that the Voltage loop control unit includes：Subtracter
With the first integrated transporting discharging；One input terminal of the subtracter receives the DC reference signal, the subtracter it is another defeated
Enter end and receives the feedback signal；The output end of the subtracter is connected with an input terminal of first integrated transporting discharging；Institute
Another input terminal for stating the first integrated transporting discharging receives the sampled signal；
Alternatively, the Voltage loop control unit includes：Adder and the second integrated transporting discharging；One input termination of the adder
Receive the feedback signal；Another input terminal of the adder receives the sampled signal；The output end of the adder with
One input terminal of second integrated transporting discharging is connected；Another input terminal of second integrated transporting discharging receives the direct current base
Calibration signal；
Wherein, the feedback signal is identical as the output ripple phase.
10. according to any LED drive circuits of claim 1-9, which is characterized in that further include dimming control unit, institute
It states dimming control unit and exports dim signal to the steady flow unit, the output current of the steady flow unit is made to change.
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| CN201610262294.4A CN105792437B (en) | 2016-04-22 | 2016-04-22 | A kind of LED drive circuit |
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| CN201610262294.4A CN105792437B (en) | 2016-04-22 | 2016-04-22 | A kind of LED drive circuit |
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| CN105792437B true CN105792437B (en) | 2018-09-04 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110971849A (en) * | 2018-09-28 | 2020-04-07 | 强弦科技股份有限公司 | Power supply for liquid crystal television |
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| US6771056B1 (en) * | 2001-10-31 | 2004-08-03 | Ixys Corporation | AC controller with reverse blocking IGBT |
| JP3710454B2 (en) * | 2003-03-31 | 2005-10-26 | Ｔｄｋ株式会社 | Power supply device and control device thereof |
| CN202059332U (en) * | 2010-02-01 | 2011-11-30 | 梁晓 | Power source of frequency-hopping resonant switch |
| US8493757B2 (en) * | 2011-05-27 | 2013-07-23 | Infineon Technologies Ag | AC/DC converter with a PFC and a DC/DC converter |
| CN103259437B (en) * | 2012-02-15 | 2017-05-10 | 欧司朗股份有限公司 | Load actuator and method for reducing output ripple current of load actuator |
| US8917032B2 (en) * | 2012-02-23 | 2014-12-23 | Maxim Integrated Products, Inc. | Method and apparatus for active ripple cancelation |
| FR2990308B1 (en) * | 2012-05-03 | 2014-04-18 | Schneider Toshiba Inverter | METHOD AND SYSTEM FOR DETECTING A FAULT ON THE CONTINUOUS BUS SUPPLYING A POWER CONVERTER |
| CN204994017U (en) * | 2015-10-10 | 2016-01-20 | 成都川睿科技有限公司 | Intelligent transportation lighting system based on electric current ripple cancelling circuit |
| CN205546102U (en) * | 2016-04-22 | 2016-08-31 | 浙江英飞特光电有限公司 | Light -emitting diode (LED) driving circuit |
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| CN110971849A (en) * | 2018-09-28 | 2020-04-07 | 强弦科技股份有限公司 | Power supply for liquid crystal television |
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