CN101932155A - Power supply circuit of light emitting diode - Google Patents

Abstract

The invention provides a power supply circuit of a light emitting diode, which receives input voltage through a first positive output end and a first negative output end of a power supply device and outputs driving voltage to a light emitting diode component, and comprises: the second positive output end and the second negative output end are connected with the light-emitting diode assembly, and the second negative output end is connected with the first negative output end; the rear-stage power supply conversion circuit is used for converting the input voltage into compensation voltage and is provided with a third positive output end connected with the second positive output end and a third negative output end connected with the first positive output end; the control circuit is connected with the rear-stage power supply conversion circuit and the light-emitting diode component and is used for detecting and controlling the current of the light-emitting diode component; the driving voltage is formed by adding an input voltage and a compensation voltage. The power supply circuit of the invention has less electric energy conversion loss to improve the efficiency, and simultaneously, the elements in the post-stage power supply conversion circuit can select the elements with lower voltage tolerance to reduce the cost.

Description

LED power supply circuit

technical field

The invention relates to a power supply circuit, in particular to a light-emitting diode power supply circuit capable of reducing power conversion loss.

Background technique

In recent years, due to breakthroughs in light emitting diode (Light Emitting Diode, LED) manufacturing technology, the luminous brightness and luminous efficiency of light emitting diodes have been greatly improved, thus making light emitting diodes gradually replace known lamp tubes and become new lighting components, widely used in For example, lighting applications such as household lighting devices, automotive lighting devices, handheld lighting devices, LCD panel backlights, traffic sign lights, and signage boards.

In order to increase the brightness of the LEDs, usually a plurality of LEDs are connected in series to form an LED module. However, due to the relationship between the LED technology, the start-up voltage of each LED will not be exactly the same, but between 3.2V and 3.6V, for example, so the start-up of the LED assembly formed by connecting multiple LEDs in series The voltage will be within a range. For example, when the LED assembly is composed of 30 LED assemblies connected in series, the start-up voltage of the LED assembly will be between 96V-108V.

At present, the light emitting diode components are all connected to a power supply circuit, so as to be illuminated by the driving of the power supply circuit. However, since the start-up voltage of the light-emitting diode assembly is within a certain range, a post-stage conversion circuit inside the power supply circuit will correspond to the start-up voltage of the light-emitting diode assembly connected to the power supply circuit, and a voltage source, such as commercial power, It is converted into the start-up voltage required by the light-emitting diode component to drive the light-emitting diode component to light up. At the same time, the power supply circuit further controls the current value flowing through the light-emitting diode component at a fixed value by adjusting the value of the driving voltage to make the light-emitting diode component glow. The brightness of the diode assembly remains constant.

However, it can be seen from the above that when the number of LEDs in the LED assembly increases, it means that the post-stage conversion circuit of the traditional power supply circuit needs to convert the received electric energy into a higher-level driving voltage. If the level conversion circuit needs to convert the electric energy provided by the voltage source into a high-level voltage, the power supply circuit has a high power conversion loss and the efficiency is not good. In addition, because the post-stage conversion circuit of the power supply circuit needs to convert the electrical energy provided by the voltage source into a high-level voltage, the components in the post-stage conversion circuit must choose components with a higher withstand voltage rating. In this way, the power supply The cost of the circuit is also relatively increased.

Therefore, how to develop a power supply circuit for light-emitting diodes that can improve the above-mentioned defects of the known technology and reduce the loss of electric energy conversion is an urgent problem that those in the relevant technical field need to solve.

Contents of the invention

The main purpose of the present invention is to provide a power supply circuit for light-emitting diodes to solve the traditional power supply circuit that needs to convert the received electric energy into a high-level voltage to drive the light-emitting diode components to light up. The power supply circuit has high power conversion loss and poor efficiency. At the same time, the components in the subsequent stage conversion circuit need to select components with higher withstand voltage ratings, which leads to a relatively high cost of the power supply circuit.

In order to achieve the above purpose, a broader embodiment of the present invention is to provide a power supply circuit, the first positive output terminal and the first negative output terminal of the power supply device receive the input voltage, and output the driving voltage to at least one light emitting diode assembly , the power supply circuit includes: a second positive output terminal connected to one end of the light-emitting diode component; a second negative output terminal connected to the other end of the light-emitting diode component and the first negative output terminal; a post-stage power conversion circuit for receiving input The voltage is converted into a compensation voltage, and has a third positive output terminal and a third negative output terminal, the third positive output terminal is connected to the second positive output terminal, and the third negative output terminal is connected to the first positive output terminal; and

The control circuit is connected with the subsequent power conversion circuit and the light-emitting diode assembly, and is used to detect and control the current of the light-emitting diode assembly to maintain a constant current of the light-emitting diode assembly; wherein, the power supply circuit passes the second positive output terminal and the second negative output terminal. The output terminal outputs a driving voltage, and the driving voltage is formed by adding the input voltage and the compensation voltage.

To achieve the above purpose, another broad implementation of the present invention is to provide a power supply circuit that receives an input voltage and outputs a driving voltage to at least one light-emitting diode assembly. The power supply circuit includes: a pre-stage power conversion circuit that receives an input voltage and It is converted into a transition voltage and has a first positive output terminal and a first negative output terminal; a second positive output terminal connected to one end of the light emitting diode component; a second negative output terminal connected to the other end of the light emitting diode component and the first negative output terminal The output terminal is connected; the rear-stage power conversion circuit is connected with the previous-stage power conversion circuit to receive the transition voltage and convert it into a compensation voltage, and has a third positive output terminal and a third negative output terminal, and the third positive output terminal is connected to the first The two positive output terminals are connected, the third negative output terminal is connected with the first positive output terminal; and the control circuit is connected with the subsequent power conversion circuit and the light emitting diode assembly, and is used to detect and control the current of the light emitting diode assembly to make the light emitting diode The current of the component is kept constant; wherein, the power supply circuit outputs a driving voltage through the second positive output terminal and the second negative output terminal, and the driving voltage is formed by adding the transition voltage and the compensation voltage.

Since the power supply circuit of the light-emitting diode of the present invention provides the drive voltage for the light-emitting diode assembly, most of it is provided by a voltage source that does not need to be converted, so that the post-stage power conversion circuit connected with the light-emitting diode assembly only needs to convert the received voltage to The low-level voltage has a small energy conversion ratio, so compared with the post-stage power conversion circuit of the traditional power supply circuit, which needs to convert the received voltage into a high-level voltage, the power supply circuit of the present invention can have a relatively low energy conversion ratio. The efficiency is improved with less power conversion loss, and at the same time, the cost is reduced because the components in the power conversion circuit of the subsequent stage can choose components with lower withstand voltage ratings.

Description of drawings

FIG. 1 : It is a circuit block diagram of a power supply circuit in a preferred embodiment of the present invention.

Fig. 2: It is a schematic diagram of the circuit structure of the power supply circuit shown in Fig. 1 .

FIG. 3 : It is a modification example of the subsequent power conversion circuit shown in FIG. 2 .

Figure 4: It is a variation example of the power supply circuit shown in Figure 1

FIG. 5 : It is a circuit block diagram of a power supply circuit in another preferred embodiment of the present invention.

Fig. 6: It is a schematic diagram of the circuit structure of the power supply circuit shown in Fig. 5 .

The reference numerals in the above-mentioned accompanying drawings are explained as follows:

1: Power supply circuit

10: Power supply device

101: The first positive output terminal

102: The first negative output terminal

11: LED components

12: The second positive output terminal

13: The second negative output terminal

14: Post-stage power conversion circuit

141: The third positive output terminal

142: The third negative output terminal

143, 144, 514: rectification filter circuit

15: Control circuit

151: First control integrated circuit

152: Second control integrated circuit

16: current sharing circuit

51: Pre-stage power conversion circuit

511: The fourth positive output terminal

512: The fourth negative output terminal

513: rectifier

V _in : input voltage

V _com : Compensation voltage

V _o : Driving voltage

V _in ′: Transition voltage

G: common terminal

G ₁ : LED

T ₁ , T ₂ : Transformer

N _f1 , N _f2 : primary winding

N _s1 , N _s2 : Secondary winding

Q ₁ to Q ₄ : Switching elements

D ₁ ~ D ₄ : Diodes

C ₁ ~C ₅ : Capacitance

L: inductance

Detailed ways

Some typical embodiments embodying the features and advantages of the present invention will be described in detail in the description in the following paragraphs. It should be understood that the present invention can have various changes in different ways without departing from the scope of the present invention, and that the description and drawings therein are illustrative in nature rather than limiting the present invention.

Please refer to FIG. 1 , which is a schematic block diagram of a power supply circuit according to a preferred embodiment of the present invention. As shown in FIG. 1 , the power supply circuit 1 of this embodiment receives an input voltage V in through a first positive output terminal 101 and a first negative output terminal 102 _of a power supply device 10, and outputs a driving voltage V _o to At least one LED assembly 11 is used to drive the LED assembly 11 to light up, wherein the LED assembly 11 may be but not limited to be formed by connecting a plurality of LEDs _G1 in series.

The power supply circuit 1 mainly includes a second positive output terminal 12, a second negative output terminal 13, a subsequent power conversion circuit 14 and a control circuit 15, wherein the second positive output terminal 12 is connected to one end of the light emitting diode assembly 11, The second negative output terminal 13 is connected to the other end of the light-emitting diode assembly 11, the common terminal G, and the first negative output terminal 102 of the power supply device 10, and the subsequent power conversion circuit 14 receives the input voltage V _in through the power supply device 10, and convert the input voltage V _in into a compensation voltage V _com , and the subsequent stage power conversion circuit 14 has a third positive output terminal 141 and a third negative output terminal 142 , wherein the third positive output terminal 141 and the power supply circuit 1 The second positive output terminal 12 is connected, the third negative output terminal 142 is connected to the first positive output terminal 101 of the power supply device 10, and the control circuit 15 is connected to the subsequent power conversion circuit 14 and the light emitting diode assembly 11 for detecting The magnitude of the current of the LED assembly 11 , and then control the magnitude of the current of the LED assembly 11 to keep the current of the LED assembly 11 constant.

In this embodiment, the power supply circuit 1 outputs the driving voltage V _o to the LED assembly 11 through the second positive output terminal 12 and the second negative output terminal 13 . In addition, since the third positive output terminal 141 of the subsequent power conversion circuit 14 is connected to the second positive output terminal 12 of the power supply circuit 1 , and the third negative output terminal 142 of the subsequent power conversion circuit 14 is connected to the first positive output terminal 14 of the power supply device 10 The positive output terminal 101 is connected, and the second negative output terminal 13 of the power supply circuit 1 is connected to the first negative output terminal 102 of the power supply device 10. Therefore, through the above connection relationship, the second positive output terminal 12 of the power supply circuit 1 and the second negative output terminal 10 of the power supply circuit 1 The voltage difference between the two negative output terminals 13 is the compensation voltage V _com plus the input voltage _Vin . In other words, the driving voltage V _o output by the power supply circuit 1 is formed by the compensation voltage V _com plus the input voltage _Vin .

It can be seen from the above that since the driving voltage V _o output from the power supply circuit 1 to the LED assembly 11 is formed by the compensation voltage V _com plus the input voltage _Vin , the power supply circuit 1 can pass through the LED assemblies 11 corresponding to different start-up voltages. The power supply device 10 directly provides most of the electric energy required by the light-emitting diode assembly 11, so that the power conversion circuit 14 of the subsequent stage only needs to provide the electric energy required within the voltage range of the light-emitting diode assembly 11, that is, the power conversion circuit of the subsequent stage The circuit 14 only needs to convert the input voltage V _in to a lower-level compensation voltage V _com , so compared with the post-stage power conversion circuit of the traditional power supply circuit, it needs to convert the received voltage into a high-level voltage. The post-stage power conversion circuit 14 has a smaller energy conversion ratio because it converts the received electric energy into a low-level voltage, so that the power supply circuit 1 can reduce power conversion losses and improve efficiency. In addition, the power supply circuit 1 can also The production cost is reduced because the components in the power conversion circuit 14 of the subsequent stage can be selected from components with a low withstand voltage rating.

For example, when the LED assembly 11 includes 30 LEDs G ₁ , and the start-up voltage of each LED G ₁ is between 3.2V-3.6V, the start-up voltage of the LED assembly 11 is between 96V-108V, And if the input voltage V _in of the power supply device 10 is 80V, relatively, the subsequent power conversion circuit 14 only needs to convert the received input voltage V _in into a compensation voltage V _com with a voltage level of 16V-28V, so As a result, not only the light-emitting diode assembly 11 can be driven to light up, but also because the power conversion circuit 14 in the subsequent stage converts the input voltage V _in into a low-level compensation voltage V _com and has a relatively low energy conversion ratio, the power supply circuit 1 is convenient. The power conversion loss can be reduced and the efficiency can be improved. At the same time, the cost of the power supply circuit 1 can be relatively reduced because the components in the subsequent power conversion circuit 14 can be selected with lower withstand voltage ratings.

In the above-mentioned embodiments, the subsequent stage power conversion circuit 14 may be but not limited to a DC-DC conversion circuit, so relatively, the voltage received by the subsequent stage power conversion circuit 14 is a DC voltage, that is, the subsequent stage power conversion circuit 14 The input voltage V _in received by the power supply device 10 is a DC voltage. In addition, the input voltage _Vin can also be but not limited to a voltage with a fixed level, and the level of the input voltage _Vin can be adjusted or set according to the number of the LEDs G ₁ of the LED assembly 11 . In addition, in other embodiments, the power supply device 10 can be a power factor correction circuit, but it is not limited thereto.

The technique of the present invention will be described below by taking a flyback DC-DC conversion circuit as an example in which the subsequent power conversion circuit of the power supply circuit of the present invention is used. Please refer to FIG. 2 , which is a schematic diagram of the circuit structure of the power supply circuit shown in FIG. 1 . As shown in the figure, the control circuit 15 includes a first control integrated circuit (control integrated circuit) 151, and the subsequent stage power conversion circuit 14 may be but not limited to a flyback DC-DC power conversion circuit, and includes a first transformer T ₁ , a first switching element Q ₁ and a first rectification and filtering circuit 143 . Wherein, the first transformer T ₁ has a first primary winding N _f1 and a first secondary winding N _s1 , the first primary winding N _f1 is connected to the first positive output terminal 101 of the power supply device 10 and the first switching element Q ₁ connected, the secondary winding N _s1 is connected to the first rectifying and filtering circuit 143 and the first positive output terminal 101 of the power supply device 10, the first switching element _Q1 is connected in series between the primary winding N _f1 and the common terminal G, and the second The control terminal of a switching element _Q1 is connected to the first control integrated circuit 151 of the control circuit 15, and the first switching element _Q1 is controlled by the first control integrated circuit 151 of the control circuit 15 to be turned on or off, so that the transformer The first primary winding N _f1 of T ₁ electromagnetically transmits the received electric energy to the first secondary winding N _s1 , and induces electric energy on the first secondary winding N _s1 .

As for the first rectification and filtering circuit 143, the electric energy on the first secondary winding N _s1 is rectified and filtered to output the compensation voltage V _com . In some embodiments, the first rectification and filtering circuit 143 may include, but is not limited to, a first diode D ₁ and a first capacitor C ₁ , wherein the anode of the first diode D ₁ is connected to the first transformer T1 The first secondary winding N _s1 of the first diode D1 is connected, the cathode terminal of the first diode _D1 is connected with the third positive output terminal 141 of the subsequent stage power conversion circuit 14, and one end of the first capacitor _C1 is connected with the first diode The cathode terminal of the tube _D1 is connected to the third positive output terminal 141 of the subsequent stage power conversion circuit 14, and the other end of the first capacitor _C1 is connected to the third negative output terminal 142 of the subsequent stage power conversion circuit 14, and through the second The three negative output terminals 142 are connected to the first positive output terminal 101 of the power supply device 10 .

Of course, the post-stage power conversion circuit 14 is not limited to being a flyback DC-DC conversion circuit as described above. In other embodiments, as shown in FIG. 3 , the post-stage power conversion circuit 14 can also be a buck-boost The DC-DC conversion circuit includes a boost inductor L, a fourth switch element Q ₄ and a third rectification and filtering circuit 144 . One end of the boost inductor L is connected to the first positive output end 101 of the power supply device 10 , and the other end of the boost inductor L is connected 144 to one end of the fourth switching element _Q4 and the third rectifying and filtering circuit. The other end of the fourth switch _Q4 is connected to the common terminal G, and the control end of the fourth switch _Q4 is connected to the first control integrated circuit 151 of the control circuit 15, and the fourth switching element _Q4 is controlled by the first control circuit 151 of the control circuit 15. A control integrated circuit 151 is controlled to turn on or off, so that the boost inductor L boosts the received electric energy, and the third rectifying and filtering circuit 144 receives the boosted electric energy transmitted from the boost inductor L, And the boosted electric energy is rectified and filtered to output the compensation voltage V _com .

In some embodiments, the third rectification and filtering circuit 144 may include, but is not limited to, a fourth diode D ₄ and a fifth capacitor C ₅ , wherein the anode terminal of the fourth diode D ₄ is connected to the boost inductor L connected, the cathode end of the fourth diode _D4 is connected to the third positive output end 141 of the subsequent stage power conversion circuit 14, and one end of the fifth capacitor _C5 is connected to the cathode end of the fourth diode _D4 and the rear end The third positive output terminal 141 of the stage power conversion circuit 14 is connected, and the other end of the fifth capacitor _C5 is connected with the third negative output terminal 142 of the subsequent power conversion circuit 14, and is connected to the power supply via the third negative output terminal 142. The first positive output 101 of the device 10 is connected.

In some embodiments, as shown in FIG. 4 , the power supply circuit 1 can be further connected to a plurality of LED assemblies 11 connected in parallel to simultaneously drive multiple LED assemblies 11 to light up. In addition, in order to make each LED assembly 11 have the same brightness, the power supply circuit 1 can be but not limited to have a current equalizing circuit 16, the current equalizing circuit 16 is connected to the third positive output terminal 141 of the power conversion circuit 141 of the subsequent stage and a plurality of light emitting diode assemblies 11, its It is used to balance the magnitude of the current of multiple LED assemblies 11 , so that the brightness of each LED assembly 11 is the same.

Please refer to FIG. 5 , which is a power supply circuit of another preferred embodiment of the present invention. As shown in the figure, the structure of the power supply circuit 4 of this embodiment is similar to the structure of the power supply circuit 1 shown in FIG. 1 , so components with the same symbols represent similar structures and functions. Compared with the power supply circuit 1 shown in FIG. 1 , the power supply circuit 4 of this embodiment further has a front-stage power conversion circuit 51, which is connected between the power supply device 10 and the rear-stage power conversion circuit 14, and is connected to the control circuit 15. connected, and has a fourth positive output terminal 511 and a fourth negative output terminal 512, the pre-stage power conversion circuit 51 is used to receive the input voltage V _in from the power supply device 10, and is controlled by the control circuit 15 Convert the input voltage V _in to a transition voltage V _in ', so as to output the transition voltage V _in ' through the fourth positive output terminal 511 and the fourth negative output terminal 512, and the power conversion circuit 14 of the subsequent stage receives the transition voltage V instead _in ′, and converted to compensation voltage V _com . In addition, compared with the power supply circuit 1 shown in FIG. 1 , the second negative output terminal 13 of the power supply circuit 4 in this embodiment is connected to the fourth negative output terminal 512 of the previous stage power conversion circuit 51, while the latter stage power conversion circuit The third negative output terminal 142 of 14 is connected to the fourth positive output terminal 511 of the previous stage power conversion circuit 51, so that the driving voltage V _o provided by the power supply circuit 4 to the light emitting diode assembly 11 is changed from the compensation voltage V _com Formed by adding the transition voltage V _in '.

Similar to the power supply circuit 1 shown in FIG. 1, since the driving voltage V o output from the power supply circuit 4 of this embodiment to the light-emitting diode assembly 11 is formed by the compensation voltage V _com plus the transition voltage V _in ', it corresponds to different _start -up voltage of the LED assembly 11, the power supply circuit 4 can directly provide most of the electric energy required by the LED assembly 11 through the transition voltage V _in ′ output by the front-stage power conversion circuit 51, so that the rear-stage power conversion circuit 14 will be It only needs to provide the required electric energy within the voltage range of the light-emitting diode assembly 11, that is, the subsequent power conversion circuit 14 only needs to convert the transition voltage V _in ' into a low-level compensation voltage V _com , so compared with the traditional power supply circuit The post-stage power conversion circuit needs to convert the received voltage into a high-level voltage. The post-stage power conversion circuit 14 of this embodiment has a smaller energy conversion ratio because it converts the received electric energy into a low-level voltage. Therefore, the power supply circuit 4 can reduce the power conversion loss and improve the efficiency. In addition, the power supply circuit 4 can further reduce the production cost because the components in the subsequent power conversion circuit 14 can choose components with low withstand voltage ratings.

In the above-mentioned embodiment, the front-stage power conversion circuit 51 can be, but not limited to, an AC-DC conversion circuit, so relatively, the electric energy received by the front-stage power conversion circuit 51 is an AC voltage, that is, the front-stage power conversion circuit 51 The input voltage V _in received by the power supply device 10 is an AC voltage.

The technology of the present invention will be described below by taking a half-bridge AC-DC conversion circuit as an example in which the front-stage power conversion circuit of the power supply circuit is used. Please refer to FIG. 6 , which is a schematic diagram of the circuit structure of the power supply circuit shown in FIG. 5 . As shown in the figure, the post-stage power conversion circuit 14 can be, but not limited to, a flyback DC-DC conversion circuit, which has a first transformer T ₁ , a first switching element Q ₁ and a first rectification and filtering circuit 143, and the The structures and functions of the above components have been described in detail in the embodiment shown in FIG. 2 , so details are not repeated here.

In addition to the first control integrated circuit 151 , the control circuit 15 further has a second control integrated circuit 152 . The pre-stage power conversion circuit 51 can be but not limited to a half-bridge AC-DC conversion circuit, which has a rectifier 513, a second transformer T ₂ , a second switching element Q ₂ , a third switching element Q ₃ , a second The capacitor _C2 and a second rectification filter circuit 514, wherein the rectifier 513 is connected to the power supply device 10 for rectifying the input voltage V _in . The second switching element _Q2 is respectively connected to the rectifier 513 and the third switching element _Q3 , and the third switching element _Q3 is connected to the common terminal G. In addition, the control terminals of the second switching element _Q2 and the third switching element _Q3 Both are connected to the second control integrated circuit 152 of the control circuit 15 , and the second switch element Q ₂ and the third switch element Q ₃ are alternately turned on or off under the control of the second control integrated circuit 152 of the control circuit 15 .

One end of the second capacitor _C2 is connected between the second switch element _Q2 and the third switch element _Q3 , and the second capacitor _C2 is used for filtering. The second transformer T ₂ has a second primary winding N _f2 and a second secondary winding N _s2 , wherein both ends of the second primary winding N _f2 are respectively connected to the other end of the second capacitor C ₂ and the common terminal G, and the The second secondary winding _{Nf2 has a} center tap and is connected to the common terminal G. The second transformer _T2 makes the second primary winding N The electric energy received by _f2 is electromagnetically transmitted to the second secondary winding N _s2 , and induces electric energy on the second secondary winding N _s2 .

As for the second rectification and filtering circuit 514, it is connected with the second secondary winding N _s2 of the second transformer T ₂ , the fourth positive output terminal 511 and the fourth negative output terminal 512 of the previous stage power conversion circuit 51 for rectification and filtering . And in some embodiments, the second rectification and filtering circuit 514 may be but not limited to include a second diode D ₂ , a third diode D ₃ and a fourth capacitor C ₄ , wherein the second diode The anode terminals of D ₂ and the third diode D ₃ are respectively connected to the two ends of the second secondary winding N _s2 of the second transformer T ₂ , and the anode terminals of the second diode D ₂ and the third diode D ₃ The cathode terminals are connected to each other, one end of the fourth capacitor _C4 is connected to the cathode terminals of the second diode _D2 and the third diode _D3 and the fourth positive output terminal 511 of the previous stage power conversion circuit 51, and the fourth capacitor C4 The other end of the four capacitors _C4 is connected to the fourth negative output end 512 and the common end G of the previous stage power conversion circuit 51 .

To sum up, since the LED power supply circuit of the present invention provides most of the driving voltage to the LED assembly from a voltage source that does not need to be converted, the post-stage power conversion circuit connected to the LED assembly only needs to convert the The received voltage is converted to a low-level voltage and has a small energy conversion ratio. Therefore, compared with the post-stage power conversion circuit of the traditional power supply circuit, the received voltage needs to be converted into a high-level voltage. The power supply circuit of the present invention The efficiency can be improved due to less power conversion loss, and at the same time, the cost can be reduced because the components in the subsequent power conversion circuit can choose components with lower withstand voltage ratings.

The present invention can be modified in various ways by those skilled in the art without departing from the protection scope of the appended claims.

Claims (26)

1. A power supply circuit, receiving an input voltage from a first positive output terminal and a first negative output terminal of a power supply device, and outputting a driving voltage to at least one light emitting diode assembly, the power supply circuit comprising: a second positive output terminal connected to one end of the light emitting diode assembly; a second negative output terminal connected to the other end of the light emitting diode assembly and the first negative output terminal; A post-stage power conversion circuit, used to receive the input voltage and convert it into a compensation voltage, and has a third positive output terminal and a third negative output terminal, the third positive output terminal is connected to the second positive output terminal , the third negative output terminal is connected to the first positive output terminal; and A control circuit, connected to the subsequent power conversion circuit and the light emitting diode assembly, used to detect and control the current of the light emitting diode assembly, so as to maintain a constant current of the light emitting diode assembly; Wherein, the power supply circuit outputs the driving voltage through the second positive output terminal and the second negative output terminal, and the driving voltage is formed by adding the input voltage and the compensation voltage. 2. The power supply circuit as claimed in claim 1, wherein the light emitting diode assembly is composed of a plurality of light emitting diodes connected in series. 3. The power supply circuit as claimed in claim 2, wherein the start-up voltage of the LED assembly is within a range. 4. The power supply circuit as claimed in claim 1, wherein the input voltage is a DC voltage. 5. The power supply circuit as claimed in claim 1, wherein the subsequent power conversion circuit is a flyback DC-DC conversion circuit or a buck-boost DC-DC conversion circuit. 6. The power supply circuit as claimed in claim 1, wherein the control circuit comprises a control integrated circuit. 7. The power supply circuit according to claim 6, wherein the subsequent power conversion circuit comprises a switch element connected to the control integrated circuit of the control circuit, which is turned on or off by the control circuit. 8. The power supply circuit as claimed in claim 7, wherein the post-stage power conversion circuit comprises a transformer, the transformer has a primary winding and a secondary winding, wherein the primary winding is connected to the first positive output terminal of the power supply device and the switching element is connected. 9. The power supply circuit as claimed in claim 8, wherein the subsequent power conversion circuit comprises a rectification and filtering circuit connected to the secondary winding of the transformer for rectification and filtering. 10. The power supply circuit as claimed in claim 9, wherein the rectification filter circuit comprises a diode and a capacitor. 11. The power supply circuit as claimed in claim 7, wherein the post-stage power conversion circuit comprises a boost inductor, wherein one end of the boost inductor is connected to the first positive output terminal of the power supply device, and the boost inductor The other end is connected to the switching element. 12. The power supply circuit as claimed in claim 11, wherein the subsequent power conversion circuit comprises a rectification and filtering circuit connected to the other end of the boost inductor for rectification and filtering. 13. The power supply circuit according to claim 1, wherein the power supply circuit further has a current equalizing circuit, which is connected to the third positive output terminal of the subsequent stage power conversion circuit and the light-emitting diode components connected in parallel, which are used for and balance the current magnitude of the light emitting diode assembly. 14. The power supply circuit as claimed in claim 1, wherein the power supply device is a power factor correction circuit. 15. A power supply circuit that receives an input voltage and outputs a driving voltage to at least one light emitting diode assembly, the power supply circuit comprising: A pre-stage power conversion circuit receives the input voltage and converts it into a transition voltage, and has a first positive output terminal and a first negative output terminal; a second positive output terminal connected to one end of the light emitting diode assembly; a second negative output terminal connected to the other end of the light emitting diode assembly and the first negative output terminal; A rear-stage power conversion circuit, connected to the front-stage power conversion circuit, used to receive the transition voltage and convert it into a compensation voltage, and has a third positive output terminal and a third negative output terminal, the third positive output terminal is connected to the second positive output terminal, and the third negative output terminal is connected to the first positive output terminal; and A control circuit, connected to the subsequent power conversion circuit and the light emitting diode assembly, used to detect and control the current of the light emitting diode assembly, so as to maintain a constant current of the light emitting diode assembly; Wherein, the power supply circuit outputs the driving voltage through the second positive output terminal and the second negative output terminal, and the driving voltage is formed by adding the transition voltage and the compensation voltage. 16. The power supply circuit as claimed in claim 15, wherein the input voltage is an AC voltage. 17. The power supply circuit as claimed in claim 16, wherein the pre-stage power conversion circuit is a half-bridge conversion circuit. 18. The power supply circuit as claimed in claim 15, wherein the control circuit comprises a first control integrated circuit and a second control integrated circuit. 19. The power supply circuit as claimed in claim 18, wherein the post-stage power conversion circuit comprises a first switching element, a first transformer and a first rectification and filtering circuit, the first switching element and the first switching element of the control circuit A control integrated circuit is connected to be turned on or off under the control of the first control integrated circuit. 20. The power supply circuit as claimed in claim 18, wherein the front-stage power conversion circuit comprises a rectifier for rectifying the input voltage. 21. The power supply circuit as claimed in claim 20, wherein the front stage power conversion circuit comprises a second switch element and a third switch element, the second switch element and the third switch element are connected with the control circuit The second control integrated circuit is connected, and the second switch element and the third switch element are controlled by the second control integrated circuit to be alternately turned on or off. 22. The power supply circuit according to claim 21, wherein the front-stage power conversion circuit comprises a first capacitor, one end of the first capacitor is connected to the second switching element and the third switching element, and the first capacitor is used for to filter. 23. The power supply circuit as claimed in claim 22, wherein the pre-stage power conversion circuit comprises a second transformer, the second transformer has a primary winding and a secondary winding, wherein both ends of the primary winding are respectively connected to the first capacitor and a total of terminal connections. 24. The power supply circuit as claimed in claim 23, wherein the pre-stage power conversion circuit comprises a second rectification and filtering circuit connected to the secondary winding of the second transformer for rectification and filtering. 25. The power supply circuit as claimed in claim 24, wherein the second rectification filter circuit comprises a plurality of diodes and a second capacitor. 26. The power supply circuit as claimed in claim 23, wherein the secondary winding has a center tap and is connected to the common terminal.

Images