Control circuit with adjustable PFC (Power Factor Correction) working mode

Abstract

The utility model discloses a control circuit with an adjustable PFC working mode. The control circuit comprises a rectification filtering module, a PFC module, a power supply module, a DC-DC module, a detection module, a comparison module and a control module. The input end of the rectification filtering module is connected with an external power supply, and the output end is connected with the input end of the PFC module. One end of the PFC module is connected with the input end of the DC-DC module, and the other end of the PFC module is connected with the output end of the control module; the input end of the power supply module is connected with an external power supply for supplying power to a post-stage circuit; the output end of the DC-DC module is connected to the terminal V + and is connected with the input end of the detection module; one end of the detection module is connected with the terminal V-, and the other end is connected with the control module through the comparison module; the control module can adjust the voltage division value of a grounding resistor R1 of a power MOS tube Q1 in the PFC module according to the output result of the comparison module. Through the above structure, the whole PFC system does not enter an intermittent state when the load is light, and does not stop working due to overlarge detection resistance when the power is full, so that PF and THD parameters are prevented from being influenced.

Description

Technical Field

[0001] The utility model relates to the field of power supply circuits and controller circuits, and in particular to a control circuit with an adjustable PFC working mode. Background Art

[0002] With the popularity of LED lights, the diversification of LED power supplies has also emerged, and now there is more attention on the problem of LED flicker. The PFC circuit is the most effective circuit to solve the flicker problem, but most of the PFC post-stage circuit chips on the market will enter the intermittent mode when dimming into light load. This mode will directly affect the performance of the post-stage DC-DC circuit and will also cause the entire power supply to present different flashing or flickering conditions; and the traditional solution is basically to increase the load or increase the resistance of the PFC-MOS grounding resistor. This method can effectively solve the problem of PFC entering the gap, but it greatly limits the product's load capacity, and the increase in the resistance of the PFC-MOS grounding resistor will seriously affect the PF value and THD of the PFC at the maximum load. If this resistance is too large, the PFC will stop working directly at the maximum load; therefore, a new control circuit with adjustable PFC working mode is urgently needed to solve the above problems. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model proposes a control circuit with adjustable PFC working mode.

[0004] An embodiment of the utility model adopts a technical solution to solve its technical problem: a control circuit with adjustable PFC working mode, including a rectifier filter module, a PFC module, a power supply module, a DC-DC module, a detection module, a comparison module and a control module;

[0005] The input end of the rectifier and filter module is connected to the external power supply, and the output end is connected to the input end of the PFC module;

[0006] One end of the PFC module is connected to the input end of the DC-DC module, and the other end is connected to the output end of the control module;

[0007] The input end of the power supply module is connected to an external power supply to supply power to the subsequent circuit;

[0008] The output end of the DC-DC module is connected to the terminal V+ and is connected to the input end of the detection module;

[0009] One end of the detection module is connected to the terminal V-, and the other end is connected to the control module through the comparison module. The lamp can be connected to the terminal V+ and the terminal V-;

[0010] The control module can adjust the voltage division value on the grounding resistor R1 of the power MOS tube Q1 in the PFC module according to the output result of the comparison module.

[0011] As one of the preferred embodiments of the utility model, the PFC module includes a transformer T1, a control chip U1, a diode D1, a capacitor C1, a MOS tube Q1, resistors R1-2, resistors R11-16 and a capacitor C3. The input end of the first winding of the transformer T1 is connected to the output end of the rectifier and filter module, the output end of the first winding of the transformer T1 is respectively connected to the anode of the diode D1 and the drain of the MOS tube Q1, the source of the MOS tube is respectively connected to one end of the resistor R1 and one end of the resistor R2, the gate of the MOS tube Q1 is connected to the 6th pin of the control chip U1, the cathode of the diode D1 is respectively connected to one end of the capacitor C1 and the input end of the DC-DC module, and the 7th pin of the control chip U1 is connected to the second winding of the transformer T1 through the resistor R16. The first end of the group is connected, the 8th pin of the control chip U1 is connected to the power supply VCC, the 1st pin of the control chip U1 is respectively connected to one end of the resistor R15 and one end of the resistor R13, the other end of the resistor R15 is connected to the output end of the rectifier and filter module, the 2nd pin of the control chip U1 is connected to the resistor R13 via the resistor R14 and the capacitor C3, the 4th pin of the control chip U1 is respectively connected to one end of the resistor R11 and one end of the resistor R12, the other end of the resistor R11 is connected to the cathode of the diode D1, the 5th pin of the control chip U1 is connected to the other end of the resistor R1, the other end of the resistor R2, the other end of the capacitor C1, the second end of the second winding of the transformer T1, the other end of the capacitor C3 and the other end of the resistor R12 are connected to GND.

[0012] As one of the preferred embodiments of the present utility model, the detection module includes a resistor R17 connected in series between the DC-DC module and the terminal V-, and the comparison module is connected to both ends of the resistor R17.

[0013] As one of the preferred embodiments of the utility model, the comparison module includes a comparator U3A, resistors R5-8, a resistor R10 and a capacitor C2. The power supply end of the comparator U3A is respectively connected to the power supply VDD, one end of the capacitor C2 and one end of the resistor R5. The other end of the resistor R5 is respectively connected to one end of the resistor R6 and one end of the resistor R7. The other end of the resistor R6 is connected to the positive input end of the comparator U3A. The reverse input end of the comparator U3A is connected to the detection module via the resistor R8. The output end of the comparator U3A is connected to the control module via the resistor R10. The other end of the capacitor C2, the ground end of the comparator U3A and the other end of the resistor R7 are commonly connected to GNS.

[0014] As one of the preferred embodiments of the present utility model, a control circuit with adjustable PFC working mode further includes an amplification module connected between the detection module and the comparison module.

[0015] As one of the preferred embodiments of the utility model, the amplification module includes resistors R18-20 and an amplifier U3B, one end of the resistor R19 is connected to one end of the detection module, one end of the resistor R18 is connected to the other end of the detection module, the other end of the resistor R18 is connected to the positive input end of the amplifier U3B, the other end of the resistor R19 is respectively connected to the reverse input end of the amplifier U3B and one end of the resistor R20, the other end of the resistor R20 is respectively connected to the output end of the amplifier U3B and the comparison module, the power supply end of the amplifier U3B is connected to the power supply VDD, and the ground end of the amplifier U3B is connected to GNS.

[0016] As one of the preferred embodiments of the utility model, the control module includes an optocoupler U2, a MOS tube Q2, resistors R3-4 and a resistor R9, one end of the optocoupler U2 light emitter is connected to the output end of the comparison module, the other end of the optocoupler U2 light emitter is connected to GNS, one end of the optocoupler U2 light receiver is connected to the power supply VCC via the resistor R9, the other end of the optocoupler U2 light receiver is respectively connected to one end of the resistor R4 and the gate of the MOS tube Q2, the other end of the resistor R4 and the drain of the MOS tube Q2 are connected to GND, and the source of the MOS tube Q2 is connected to the grounding resistor R1 of the power MOS tube Q1 in the PFC module via the resistor R3.

[0017] The beneficial effects of the utility model are as follows: a control circuit with adjustable PFC working mode, comprising a rectifier filter module, a PFC module, a power supply module, a DC-DC module, a detection module, a comparison module and a control module; the input end of the rectifier filter module is connected to an external power supply, and the output end is connected to the input end of the PFC module; one end of the PFC module is connected to the input end of the DC-DC module, and the other end is connected to the output end of the control module; the input end of the power supply module is connected to the external power supply for supplying power to the subsequent circuit; the output end of the DC-DC module is connected to the terminal V+ and the input end of the detection module; one end of the detection module is connected to the terminal V-, and the other end is connected to the control module via the comparison module, and the lamp can be connected to the terminal V+ and the terminal V-; the control module can adjust the voltage division value on the grounding resistor R1 of the power MOS tube Q1 in the PFC module according to the output result of the comparison module; through the above structure, the entire PFC system can not enter the intermittent state when the load is light, and will not stop working due to the excessive detection resistance when the load power is full, thereby avoiding affecting the PF and THD parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1It is a principle block diagram of a control circuit with adjustable PFC working mode;

[0020] Figure 2 The invention is a circuit schematic diagram of a control circuit with adjustable PFC working mode. DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0022] In the description of the present utility model, the meaning of "more than" is more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0023] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] In the present invention, unless otherwise clearly defined, the words "set", "install", "connect" and the like should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium; they can be fixedly connected or detachably connected or integrally formed; they can be mechanically connected; they can be the internal connection of two elements or the interaction relationship between two elements. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0025] Reference Figure 1 to Figure 2 , a control circuit with adjustable PFC working mode, including a rectifier and filter module 10, a PFC module 20, a power supply module 30, a DC-DC module 40, a detection module 50, a comparison module 60 and a control module 70;

[0026] The input end of the rectifier and filter module 10 is connected to the external power supply, and the output end is connected to the input end of the PFC module 20;

[0027] One end of the PFC module 20 is connected to the input end of the DC-DC module 40 , and the other end is connected to the output end of the control module 70 ;

[0028] The input end of the power supply module 30 is connected to an external power source for supplying power to the subsequent circuit;

[0029] The output end of the DC-DC module 40 is connected to the terminal V+ and is connected to the input end of the detection module 50;

[0030] One end of the detection module 50 is connected to the terminal V-, and the other end is connected to the control module 70 via the comparison module 60. The lamp can be connected to the terminal V+ and the terminal V-;

[0031] The control module 70 can adjust the voltage division value on the grounding resistor R1 of the power MOS tube Q1 in the PFC module 20 according to the output result of the comparison module 60 .

[0032] In the present utility model, the input end of the rectifier and filter module 10 is respectively connected to the mains neutral line L, the live line N and the input end of the power supply module 30. The rectifier and filter module 10 provides a stable DC voltage to the PFC module 20. The output end of the power supply module 30 provides power VCC for each primary chip and device and power VDD for each secondary chip and device. It should be noted that when the system is powered on, the rectifier and filter module 10 converts the input AC voltage into a DC voltage and inputs it to the PFC module 20. The power supply module 30 internally controls the output timing of the power supply VCC and the power supply VDD, and preferentially outputs the power supply VDD, and then outputs the power supply VCC, so as to ensure that the control module 70 works in advance when the system is powered on, and prevents the PFC module 20 from being unable to output normally when powered on. Specifically:

[0033] ① In the PFC module 20, the PFC module 20 includes a transformer T1, a control chip U1, a diode D1, a capacitor C1, a MOS tube Q1, resistors R1-2, resistors R11-16 and a capacitor C3. The input end of the first winding of the transformer T1 is connected to the output end of the rectifier filter module 10. The output end of the first winding of the transformer T1 is respectively connected to the anode of the diode D1 and the drain of the MOS tube Q1. The source of the MOS tube is respectively connected to one end of the resistor R1 and one end of the resistor R2. The gate of the MOS tube Q1 is connected to the 6th pin of the control chip U1. The cathode of the diode D1 is respectively connected to one end of the capacitor C1 and the input end of the DC-DC module 40. The 7th pin of the control chip U1 is connected to the second winding of the transformer T1 through the resistor R16. The first end of the group is connected, the 8th pin of the control chip U1 is connected to the power supply VCC, the 1st pin of the control chip U1 is respectively connected to one end of the resistor R15 and one end of the resistor R13, the other end of the resistor R15 is connected to the output end of the rectifier and filter module 10, the 2nd pin of the control chip U1 is connected to the resistor R13 via the resistor R14 and the capacitor C3, the 4th pin of the control chip U1 is respectively connected to one end of the resistor R11 and one end of the resistor R12, the other end of the resistor R11 is connected to the cathode of the diode D1, the 5th pin of the control chip U1 is connected to the other end of the resistor R1, the other end of the resistor R2, the other end of the capacitor C1, the second end of the second winding of the transformer T1, the other end of the capacitor C3 and the other end of the resistor R12 are connected to GND.

[0034] ② In the detection module 50, the detection module 50 includes a resistor R17 connected in series between the DC-DC module 40 and the terminal V-, and the comparison module 60 is connected to both ends of the resistor R17. The voltage output by the DC-DC module 40 generates a voltage drop on the resistor R17 and is fed back to the comparison module 60.

[0035] ③ In one embodiment, the comparison module 60 includes a comparator U3A, resistors R5-8, a resistor R10 and a capacitor C2, the power supply end of the comparator U3A is respectively connected to the power supply VDD, one end of the capacitor C2 and one end of the resistor R5, the other end of the resistor R5 is respectively connected to one end of the resistor R6 and one end of the resistor R7, the other end of the resistor R6 is connected to the positive input end of the comparator U3A, the reverse input end of the comparator U3A is connected to the detection module 50 via the resistor R8, the output end of the comparator U3A is connected to the control module 70 via the resistor R10, and the other end of the capacitor C2, the ground end of the comparator U3A and the other end of the resistor R7 are commonly connected to GNS;

[0036] Among them, the power supply VDD obtains a reference voltage VRFE after voltage division through resistors R5, R6 and R7. The reference voltage VRFE is connected to the positive input terminal of the comparator U3A. The reverse input terminal of the comparator U3A is connected to the output terminal connected to the detection module 50 through the resistor R8. The comparator U3A compares its positive input terminal and reverse input terminal. The comparison result is output through the output terminal of the comparator U3A and is connected to the control module 70 through the resistor R10.

[0037] ④ In the control module 70, the control module 70 includes an optocoupler U2, a MOS tube Q2, resistors R3-4 and a resistor R9, one end of the optocoupler U2 light emitter is connected to the output end of the comparison module 60, the other end of the optocoupler U2 light emitter is connected to GNS, one end of the optocoupler U2 light receiver is connected to the power supply VCC via the resistor R9, the other end of the optocoupler U2 light receiver is respectively connected to one end of the resistor R4 and the gate of the MOS tube Q2, the other end of the resistor R4 and the drain of the MOS tube Q2 are connected to GND, and the source of the MOS tube Q2 is connected to the grounding resistor R1 of the power MOS tube Q1 in the PFC module 20 via the resistor R3;

[0038] Among them, the output end of the comparator U3A is connected to one end of the light emitter of the optocoupler U2 through the resistor R10, one end of the light receiver of the optocoupler U2 is connected to the power supply VCC through the resistor R9, and the other end of the light receiver of the optocoupler U2 divides the power supply VCC through the resistor R4 and controls the switch of the MOS tube Q2 to realize the grounding or suspension function of the resistor R3. The resistor R3 and the grounding resistor R1 of the power MOS tube Q1 in the PFC module sample the source of the MOS tube Q1 and divide the voltage or not divide the voltage. The result of the voltage division or not divide the voltage is input to the 5th pin of the control chip U1. The control chip U1 controls the MOS tube Q1 by judging the voltage of the 5th pin, so that the entire PFC system will not enter the intermittent state when the load is light, and will not stop working due to excessive detection resistance when the power is fully loaded, thereby avoiding affecting the PF and THD parameters.

[0039] ⑤ In one embodiment, a control circuit with adjustable PFC working mode also includes an amplification module 80 connected between the detection module 50 and the comparison module 60; preferably, the amplification module 80 includes resistors R18-20 and an amplifier U3B, one end of the resistor R19 is connected to one end of the detection module 50, one end of the resistor R18 is connected to the other end of the detection module 50, the other end of the resistor R18 is connected to the positive input end of the amplifier U3B, the other end of the resistor R19 is respectively connected to the reverse input end of the amplifier U3B and one end of the resistor R20, the other end of the resistor R20 is respectively connected to the output end of the amplifier U3B and the comparison module 60, the power supply end of the amplifier U3B is connected to the power supply VDD, and the ground end of the amplifier U3B is connected to GNS; it can amplify the signal collected by the detection module 50 and output it to the comparison module 60.

[0040] ⑥ The advantage of the utility model is that: through the above structure, the entire PFC system will not enter an intermittent state when the load is light, and will not stop working due to excessive detection resistance when the power is fully loaded, thereby avoiding affecting the PF and THD parameters.

[0041] Of course, the present invention is not limited to the above-mentioned embodiments, and technicians familiar with the field may make equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications and substitutions are all included in the scope defined by the claims of this application.

Claims

1. A control circuit with adjustable PFC working mode, characterized in that: It comprises a rectification and filtering module (10), a PFC module (20), a power supply module (30), a DC-DC module (40), a detection module (50), a comparison module (60) and a control module (70); The input end of the rectification and filtering module (10) is connected to an external power supply, and the output end is connected to the input end of the PFC module (20); One end of the PFC module (20) is connected to the input end of the DC-DC module (40), and the other end is connected to the output end of the control module (70); The input end of the power supply module (30) is connected to an external power source and is used to supply power to the subsequent circuit; The output end of the DC-DC module (40) is connected to the terminal V+ and is connected to the input end of the detection module (50); One end of the detection module (50) is connected to the terminal V-, and the other end is connected to the control module (70) via the comparison module (60), and the lamp can be connected to the terminal V+ and the terminal V-; The control module (70) can adjust the voltage division value on the grounding resistor R1 of the power MOS tube Q1 in the PFC module (20) according to the output result of the comparison module (60).

2. A control circuit with adjustable PFC working mode according to claim 1, characterized in that: The PFC module (20) comprises a transformer T1, a control chip U1, a diode D1, a capacitor C1, a MOS tube Q1, resistors R1-2, resistors R11-16 and a capacitor C3; the input end of the first winding of the transformer T1 is connected to the output end of the rectifier and filter module (10); the output end of the first winding of the transformer T1 is respectively connected to the anode of the diode D1 and the drain of the MOS tube Q1; the source of the MOS tube is respectively connected to one end of the resistor R1 and one end of the resistor R2; the gate of the MOS tube Q1 is connected to the sixth pin of the control chip U1; the cathode of the diode D1 is respectively connected to one end of the capacitor C1 and the input end of the DC-DC module (40); the seventh pin of the control chip U1 is connected to the second winding of the transformer T1 via the resistor R16. The first end of the control chip U1 is connected to the first end of the control chip U1, the 8th pin of the control chip U1 is connected to the power supply VCC, the 1st pin of the control chip U1 is respectively connected to one end of the resistor R15 and one end of the resistor R13, the other end of the resistor R15 is connected to the output end of the rectifier filter module (10), the 2nd pin of the control chip U1 is connected to the resistor R13 via the resistor R14 and the capacitor C3, the 4th pin of the control chip U1 is respectively connected to one end of the resistor R11 and one end of the resistor R12, the other end of the resistor R11 is connected to the cathode of the diode D1, the 5th pin of the control chip U1 is connected to the other end of the resistor R1, the other end of the resistor R2, the other end of the capacitor C1, the second end of the second winding of the transformer T1, the other end of the capacitor C3 and the other end of the resistor R12 are connected to GND.

3. The control circuit with adjustable PFC working mode according to claim 1, characterized in that: The detection module (50) comprises a resistor R17 connected in series between the DC-DC module (40) and a terminal V-, and the comparison module (60) is connected to both ends of the resistor R17.

4. The control circuit with adjustable PFC working mode according to claim 1, characterized in that: The comparison module (60) comprises a comparator U3A, resistors R5-8, a resistor R10 and a capacitor C2, a power supply end of the comparator U3A is respectively connected to a power supply VDD, one end of the capacitor C2 and one end of the resistor R5, the other end of the resistor R5 is respectively connected to one end of the resistor R6 and one end of the resistor R7, the other end of the resistor R6 is connected to the positive input end of the comparator U3A, the negative input end of the comparator U3A is connected to the detection module (50) via the resistor R8, the output end of the comparator U3A is connected to the control module (70) via the resistor R10, and the other end of the capacitor C2, the ground end of the comparator U3A and the other end of the resistor R7 are commonly connected to GNS.

5. The control circuit with adjustable PFC working mode according to claim 1, characterized in that: The control module (70) comprises an optical coupler U2, a MOS tube Q2, resistors R3-4 and a resistor R9; one end of the light emitter of the optical coupler U2 is connected to the output end of the comparison module (60); the other end of the light emitter of the optical coupler U2 is connected to GNS; one end of the light receiver of the optical coupler U2 is connected to a power source VCC via the resistor R9; the other end of the light receiver of the optical coupler U2 is respectively connected to one end of the resistor R4 and the gate of the MOS tube Q2; the other end of the resistor R4 and the drain of the MOS tube Q2 are connected to GND; the source of the MOS tube Q2 is connected to the grounding resistor R1 of the power MOS tube Q1 in the PFC module (20) via the resistor R3.

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