CN215647484U - LED driving power supply - Google Patents
LED driving power supply Download PDFInfo
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- CN215647484U CN215647484U CN202120899010.9U CN202120899010U CN215647484U CN 215647484 U CN215647484 U CN 215647484U CN 202120899010 U CN202120899010 U CN 202120899010U CN 215647484 U CN215647484 U CN 215647484U
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Abstract
The utility model relates to an LED driving power supply, which comprises a PFC circuit and an LLC circuit which are connected, wherein the PFC circuit comprises a first detection unit for detecting the output voltage of the PFC circuit, and a PFC control chip for adjusting the output voltage of the PFC circuit according to the detection result of the first detection unit, and the LED driving power supply also comprises: a second detection unit for detecting an output voltage of the LED driving power supply; and the adjusting unit is used for adjusting the detection result of the first detection unit according to the detection result of the second detection unit. By implementing the technical scheme of the utility model, the LED driving voltage is kept at higher overall efficiency within the output range, the reliability of the power supply is improved, and the service life of the power supply is prolonged.
Description
Technical Field
The utility model relates to the field of switching power supplies, in particular to an LED driving power supply.
Background
At present, energy crisis and climate warming are prominent, so that people pay more and more attention to energy conversion efficiency and utilization efficiency. In many energy specifications, the efficiency index has a higher requirement, and therefore, the requirement of the overall efficiency of the LED driving power supply is increased. However, in order to reduce the stock pressure of customers, the range of output voltage of the current LED driving power supply is made wider, so that the efficiency difference of the same LED driving power supply is larger under different output parameters. This is clearly not the optimal way today when the energy requirements are high.
For example, for the topological design of the LED driving power supply, it includes two stages of circuits: PFC circuit, LLC circuit. In order to ensure that the output voltage of the PFC circuit is greater than the maximum input voltage when the maximum input voltage is applied, a higher fixed value needs to be set or the output voltage of the PFC circuit needs to change along with the change of the input voltage; in the LLC circuit, when the output load changes, the working frequency in the resonant cavity also changes, so that the switching frequency of the LLC circuit is far away from the designed resonant frequency, the overall efficiency becomes low, the reliability of the power supply is reduced, and the service life of the power supply is influenced. Today, the requirement on energy efficiency is higher, so that the product cannot meet the requirement on energy efficiency.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem of providing an LED driving power supply aiming at the defect of low efficiency of the LED driving power supply in the prior art.
The technical scheme adopted by the utility model for solving the technical problems is as follows: an LED driving power supply is constructed, and comprises a PFC circuit and an LLC circuit which are connected, wherein the PFC circuit comprises a first detection unit for detecting the output voltage of the PFC circuit, and a PFC control chip for adjusting the output voltage of the PFC circuit according to the detection result of the first detection unit, and the LED driving power supply further comprises:
a second detection unit for detecting an output voltage of the LED driving power supply;
and the adjusting unit is used for adjusting the detection result of the first detection unit according to the detection result of the second detection unit.
Preferably, the second detection unit includes:
the sampling module is used for sampling the output voltage of the LED driving power supply;
and the comparison module is used for comparing the sampling voltage of the sampling module with a preset reference voltage.
Preferably, the sampling module includes a first resistor and a second resistor, wherein the first resistor and the second resistor are connected in series and then connected between the output end of the LED driving power supply and ground, and a connection point of the first resistor and the second resistor is the output end of the sampling module.
Preferably, the comparison module includes a comparator, wherein a non-inverting input terminal of the comparator is connected to the output terminal of the sampling module, an inverting input terminal of the comparator is connected to the reference power supply, and an output terminal of the comparator is the output terminal of the comparison module.
Preferably, the comparison module further comprises a return difference resistor connected between a non-inverting input terminal and an output terminal of the comparator.
Preferably, the adjusting unit includes an optocoupler, a triode, and a third resistor, wherein a positive input end of the optocoupler is connected to an output end of the comparing module, a negative input end of the optocoupler is grounded, a positive output end of the optocoupler is connected to a high level, a negative output end of the optocoupler is connected to a base of the triode, an emitter of the triode is grounded, and a collector of the triode is connected to a feedback end of the PFC control chip through the third resistor.
Preferably, the adjusting unit further includes a current limiting resistor connected between the negative output terminal of the optocoupler and the base of the triode.
Preferably, the first detection unit includes a fourth resistor and a fifth resistor, a first end of the fourth resistor is connected to the positive output end of the PFC circuit, a second end of the fourth resistor is connected to the feedback end of the PFC control chip and the first end of the fifth resistor, respectively, and a second end of the fifth resistor is grounded.
Preferably, the LLC circuit includes a first switching tube, a second switching tube, a transformer and a capacitor, wherein the first switching tube and the second switching tube are connected in series and then connected between the positive output end of the PFC circuit and ground, and after the primary winding of the transformer is connected in series with the capacitor, one end is connected to a connection point of the first switching tube and the second switching tube, and the other end is grounded.
According to the technical scheme provided by the utility model, the detection voltage fed back to the PFC control chip is adjusted by detecting the output voltage of the LED driving power supply, so that the PFC control chip adjusts the output voltage of the PFC circuit, namely, the output voltage of the PFC circuit changes along with the change of the output voltage of the LED driving power supply, namely, the output voltage changes along with the change of a load, therefore, the output voltage of the PFC circuit does not need to be set to a higher fixed value or change along with the change of an input voltage, therefore, the working frequency of the LLC circuit is basically close to a resonant frequency point, so that the LED driving voltage is kept at higher overall efficiency in an output range, the reliability of the power supply is improved, and the service life of the power supply is prolonged.
Drawings
In order to illustrate the embodiments of the utility model more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being apparent that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be derived from those drawings by a person skilled in the art without inventive effort. In the drawings:
FIG. 1 is a first circuit diagram of a first embodiment of an LED driving power supply according to the present invention;
FIG. 2 is a second circuit diagram of a first embodiment of an LED driving power supply of the present invention;
fig. 3 is a third circuit diagram of the LED driving power supply according to the first embodiment of the utility model.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 3, in an embodiment of the LED driving power supply according to the present invention, the LED driving power supply includes a PFC circuit 10, an LLC circuit 20, a second detection unit 30, and an adjustment unit 40, which are connected together.
Further, the PFC circuit 10 includes a first detection unit 11 and a PFC control chip U2, wherein the first detection unit 11 is configured to detect the output voltage VBUS of the PFC circuit 10 and feed back the detection result to the PFC control chip U2, and the PFC control chip U2 is configured to adjust the output voltage of the PFC circuit according to the detection result of the first detection unit 11 (the adjustment process is not shown). Specifically, the first detecting unit 11 includes a fourth resistor and a fifth resistor R16, in this embodiment, the fourth resistor is composed of three resistors R17, R14 and R15 connected in series, but in other embodiments, a single resistor or a plurality of resistor strings connected in series, in parallel or in a mixed manner may be used. In this embodiment, a first end of the fourth resistor is connected to the positive output end of the PFC circuit, that is, the output voltage VBUS of the PFC circuit 10 is switched on, a second end of the fourth resistor is connected to the feedback end FB of the PFC control chip U2 and the first end of the fifth resistor R16, and the second end of the fifth resistor R16 is grounded.
Further, the LLC circuit 20 includes a first switch Q9, a second switch Q11, a transformer T1 and a capacitor C3, and the first switch Q9 and the second switch Q11 are MOS transistors respectively. The first switch tube Q9 and the second switch tube Q11 are connected in series and then connected between the positive output end VBUS of the PFC circuit and the ground, the primary winding of the transformer T1 is connected in series with the capacitor C3, and then one end of the primary winding is connected to the connection point of the first switch tube Q9 and the second switch tube Q11, and the other end of the primary winding is grounded. It should be noted that although the secondary side of the transformer T1 is not shown, it should be understood that the voltage of the secondary winding of the transformer T1 is rectified to supply power to the load.
Further, the second detecting unit 30 is used for detecting the output voltage VOUT of the LED driving power supply, and the adjusting unit 40 is used for adjusting the detection result of the first detecting unit 11 according to the detection result of the second detecting unit 30.
Further, the second detection unit 30 includes a sampling module 31 and a comparison module 32, where the sampling module 31 is configured to sample the output voltage VOUT of the LED driving power supply; the comparison module 32 is used for comparing the sampling voltage of the sampling module 31 with a preset reference voltage VREF 1. Specifically, the sampling module 31 includes a first resistor R9 and a second resistor R10, wherein the first resistor R9 and the second resistor R10 are connected in series and then connected between the output terminal of the LED driving power supply and the ground, and a connection point of the first resistor R9 and the second resistor R10 is the output terminal of the sampling module 31. The comparison module 32 comprises a comparator U3 and a return difference resistor R18, wherein a non-inverting input terminal of the comparator U3 is connected to an output terminal of the sampling module, that is, a connection point of the first resistor R9 and the second resistor R10 is connected, an inverting input terminal of the comparator U3 is connected to a reference power supply, an output terminal of the comparator U3 is an output terminal of the comparison module 32, and the return difference resistor R18 is connected between the non-inverting input terminal and the output terminal of the comparator U3.
Further, the adjusting unit 40 includes an opto-coupler OT1, a transistor Q3, a third resistor R8 and a current-limiting resistor R6, wherein a positive input terminal of the opto-coupler OT1 is connected to an output terminal of the comparing module, that is, the output terminal of the comparator U3 is connected, a negative input terminal of the opto-coupler OT1 is grounded, a positive output terminal of the opto-coupler OT1 is connected to the high-level VCC, a negative output terminal of the opto-coupler OT1 is connected to a base of the transistor Q3 through the current-limiting resistor R6, an emitter of the transistor Q3 is grounded, and a collector of the transistor Q3 is connected to the feedback terminal FB of the PFC control chip U2 through the third resistor R8.
The operating principle of the LED driving power supply of this embodiment is explained below:
when the circuit normally operates, the first detection unit composed of the fourth resistor (resistors R17, R14, R15 connected in series) and the fifth resistor R16 can detect the output voltage VBUS of the PFC circuit 10 and send the output voltage VBUS to the feedback terminal FB of the PFC control chip U2, and the PFC control chip U2 adjusts the output voltage VBUS of the PFC circuit 10 according to the detected voltage. Meanwhile, the output voltage VBUS of the PFC circuit 10 is fed to the next LLC circuit 30, in the LLC circuit 30, the first switching tube Q9 and the second switching tube Q11 are controlled by the corresponding driving signals DRIVER1 and DRIVE2 to form a half bridge, and the capacitor C3 and the primary winding T1-a of the transformer T1 form an LLC resonant circuit. The secondary voltage of transformer T1 is rectified to provide an output voltage VOUT for powering a load.
When the output voltage VOUT of the LED driving power supply is increased due to load change, the output voltage VOUT is divided by the first resistors R9 and R10 and then sent to the comparator U3, at this time, the voltage at the positive input end of the comparator U3 is greater than the voltage at the negative input end, the comparator U3 outputs a high level, and further the input side OT1-a of the opto-coupler OT1 is turned on, and after the output side OT1-B of the opto-coupler OT1 is turned on, the high level voltage VCC drives the transistor Q3 to be turned on, so that the third resistor R8 is connected in parallel with the fifth resistor R16, so that the lower bias resistance of the voltage dividing circuit of the first detection unit is decreased, and the output voltage VBUS of the PFC control circuit is increased as the detection result obtained by the PFC control chip U2 from the first detection unit is decreased. When the output voltage VOUT of the LED driving power supply is reduced to the set value again, so that the voltage at the positive phase input end of the comparator U3 is lower than the voltage at the negative phase input end, the comparator U3 outputs a low level, at this time, the opto-coupler OT1 is turned off, the triode Q3 is turned off, the lower bias resistance of the voltage dividing circuit of the first detection unit is increased, and the output voltage VBUS of the PFC circuit is reduced by the PFC control chip U2. Therefore, after the output voltage VOUT of the LED driving power supply becomes low, the working frequency of the LLC circuit becomes high, and after the output voltage VBUS of the PFC circuit is reduced, the working frequency of the LLC circuit becomes low.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (9)
1. An LED driving power supply comprises a PFC circuit and an LLC circuit which are connected, wherein the PFC circuit comprises a first detection unit for detecting the output voltage of the PFC circuit, and a PFC control chip (U2) for adjusting the output voltage of the PFC circuit according to the detection result of the first detection unit, and the LED driving power supply is characterized by further comprising:
a second detection unit for detecting an output voltage of the LED driving power supply;
and the adjusting unit is used for adjusting the detection result of the first detection unit according to the detection result of the second detection unit.
2. The LED driving power supply according to claim 1, wherein the second detection unit comprises:
the sampling module is used for sampling the output voltage of the LED driving power supply;
and the comparison module is used for comparing the sampling voltage of the sampling module with a preset reference voltage.
3. The LED driving power supply according to claim 2, wherein the sampling module comprises a first resistor (R9) and a second resistor (R10), wherein the first resistor (R9) and the second resistor (R10) are connected in series and then connected between the output terminal of the LED driving power supply and ground, and the connection point of the first resistor (R9) and the second resistor (R10) is the output terminal of the sampling module.
4. The LED driving power supply according to claim 2, wherein the comparison module comprises a comparator (U3), wherein a non-inverting input terminal of the comparator (U3) is connected to the output terminal of the sampling module, an inverting input terminal of the comparator (U3) is connected to a reference power supply, and an output terminal of the comparator (U3) is the output terminal of the comparison module.
5. The LED driving power supply according to claim 2, wherein the comparison module further comprises a return difference resistor (R18) connected between a non-inverting input terminal and an output terminal of the comparator (U3).
6. The LED driving power supply according to claim 2, wherein the adjusting unit comprises an optocoupler (OT1), a transistor (Q3) and a third resistor (R8), wherein a positive input terminal of the optocoupler (OT1) is connected to the output terminal of the comparing module, a negative input terminal of the optocoupler (OT1) is grounded, a positive output terminal of the optocoupler (OT1) is connected to a high level, a negative output terminal of the optocoupler (OT1) is connected to a base terminal of the transistor (Q3), an emitter terminal of the transistor (Q3) is grounded, and a collector terminal of the transistor (Q3) is connected to the feedback terminal of the PFC control chip (U2) through the third resistor (R8).
7. The LED driving power supply according to claim 6, wherein the regulation unit further comprises a current limiting resistor (R6) connected between the negative output terminal of the optocoupler (OT1) and the base of the transistor (Q3).
8. The LED driving power supply according to claim 1, wherein the first detection unit comprises a fourth resistor and a fifth resistor (R16), a first end of the fourth resistor is connected to the positive output end of the PFC circuit, a second end of the fourth resistor is respectively connected to the feedback end of a PFC control chip (U2) and a first end of the fifth resistor (R16), and a second end of the fifth resistor (R16) is grounded.
9. The LED driving power supply according to claim 1, wherein the LLC circuit comprises a first switch tube (Q9), a second switch tube (Q11), a transformer (T1) and a capacitor (C3), wherein the first switch tube (Q9) and the second switch tube (Q11) are connected in series between a positive output terminal of the PFC circuit and ground, a primary winding of the transformer (T1) is connected in series with the capacitor (C3) and has one end connected to a connection point of the first switch tube (Q9) and the second switch tube (Q11) and the other end grounded.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120899010.9U CN215647484U (en) | 2021-04-28 | 2021-04-28 | LED driving power supply |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120899010.9U CN215647484U (en) | 2021-04-28 | 2021-04-28 | LED driving power supply |
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| CN215647484U true CN215647484U (en) | 2022-01-25 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115296528A (en) * | 2022-09-30 | 2022-11-04 | 广东东菱电源科技有限公司 | Circuit for improving wide input and output voltage LLC topological efficiency |
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- 2021-04-28 CN CN202120899010.9U patent/CN215647484U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115296528A (en) * | 2022-09-30 | 2022-11-04 | 广东东菱电源科技有限公司 | Circuit for improving wide input and output voltage LLC topological efficiency |
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