A power factor adjustment circuit for aircraft

Abstract

The present application provides a power factor adjustment circuit for aircraft, comprising: a positive voltage line, which includes a first input terminal and a first output terminal; a negative voltage line, which includes a second input terminal and a second output terminal; a first switch tube; a first sampling unit, which is used to collect input voltage information; a second sampling unit, which is used to collect output voltage information; a third sampling unit, which is used to collect input current information; a control unit, which is connected to the control end of the first switch tube, the first sampling unit, the second sampling unit and the third sampling unit respectively, and is used to control the conduction and cutoff of the first switch tube according to the input information of the first sampling unit, the second sampling unit and the third sampling unit. The power factor adjustment circuit can adjust the input current waveform to make it close to a sine wave and keep it in phase with the input voltage, thereby greatly improving the power factor of the circuit.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a power factor adjustment circuit for use on aircraft. Background Art

[0002] At present, the input circuits of most switching power supplies, aviation power supplies, household power supplies, etc. generally use full-bridge rectifier conversion circuits with large-capacity filter capacitors. The serious harmonic currents generated by the input-stage rectification and large filter capacitors endanger the normal operation of the subsequent circuits, increase the loss on the transmission line, reduce the power factor, and waste electrical energy. Summary of the invention

[0003] The purpose of the embodiment of the present application is to provide a power factor adjustment circuit for use in aircraft, which is used to adjust the input current waveform to make it close to a sine wave and keep it in phase with the input voltage, thereby significantly improving the power factor of the circuit.

[0004] To achieve the above objectives, an embodiment of the present application provides a power factor adjustment circuit for use on an aircraft, comprising:

[0005] A positive voltage line including a first input terminal and a first output terminal;

[0006] A negative voltage line including a second input terminal and a second output terminal;

[0007] A first switch tube, a first end of which is connected to the first output end of the positive voltage line, and a second end of which is connected to the second output end of the negative voltage line;

[0008] A first sampling unit, connected to the first input terminal, for collecting input voltage information;

[0009] a second sampling unit connected to the first output terminal for collecting output voltage information;

[0010] a third sampling unit connected to the second input terminal for collecting input current information;

[0011] a control unit, which is connected to the control end of the first switch tube, the first sampling unit, the second sampling unit and the third sampling unit respectively, and is used to control the conduction and cutoff of the first switch tube according to input information of the first sampling unit, the second sampling unit and the third sampling unit;

[0012] Among them, the first sampling unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a first capacitor, the first end of the first resistor is respectively connected to the first input end and the first end of the second resistor, the second end of the first resistor is connected to the first end of the third resistor, the second end of the third resistor is respectively connected to the first end of the fourth resistor and the control unit, the second end of the second resistor is respectively connected to the first end of the fifth resistor and the first end of the sixth resistor, the second end of the sixth resistor is connected to the control unit, the first end of the first capacitor is connected to the second end of the second resistor, and the second end of the fourth resistor, the second end of the fifth resistor and the second end of the first capacitor are all grounded.

[0013] The power factor adjustment circuit can continuously adjust the input current waveform to make it close to a sine wave and keep it in phase with the input voltage by using the control unit to properly control the circuit, thereby greatly improving the power factor. On the other hand, setting the first capacitor in the first sampling unit can effectively improve harmonic distortion and reduce the waveform distortion of the input current. The first capacitor is connected to the sampling loop of the input voltage. After the first capacitor is set, it can delay the input voltage, thereby affecting the control unit's detection of the input voltage, indirectly affecting the output of the control unit, and further improving the input current waveform and the phase difference between the input voltage and the input current.

[0014] In one embodiment, the second sampling unit includes a seventh resistor, at least one eighth resistor and a ninth resistor, the first end of the seventh resistor is connected to the second output end, the second end of the seventh resistor is connected to the first end of the at least one eighth resistor and the first end of the ninth resistor respectively, the second end of the at least one eighth resistor is connected to the first output end, and the first end and the second end of the ninth resistor are both connected to the control unit.

[0015] In the present application, the second sampling unit is provided to effectively detect the output voltage of the power factor adjustment circuit.

[0016] In one embodiment, the third sampling unit includes a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor, the tenth resistor is connected in series between the second input terminal and the second output terminal, the first end of the eleventh resistor is connected to the second input terminal, the second end of the eleventh resistor is connected to the control unit, the first end of the twelfth resistor is connected to the second output terminal, the second end of the twelfth resistor is connected to the first end of the thirteenth resistor, the second end of the thirteenth resistor is respectively connected to the control unit and the first end of the fourteenth resistor, and the second end of the fourteenth resistor is connected to the control unit.

[0017] In the present application, the third sampling unit is provided to effectively detect the input current of the power factor adjustment circuit.

[0018] In one embodiment, the control unit also includes an output unit, which is respectively connected to the control unit and the control end of the first switch tube; the output unit includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a first diode and a second diode, the first end of the fifteenth resistor and the first end of the sixteenth resistor are connected to the control end of the first switch tube, the second end of the fifteenth resistor is connected to the second output end, the anode of the first diode is connected to the first end of the sixteenth resistor, the cathode of the first diode is connected to the second end of the sixteenth resistor, the first end of the seventeenth resistor and the cathode of the second diode, the second end of the seventeenth resistor is connected to the control unit, and the anode of the second diode is grounded.

[0019] In the present application, the control unit applies a voltage to the control end of the first switch tube through the output unit to control the on and off of the first switch tube.

[0020] In one embodiment, the power factor adjustment circuit also includes a power supply unit, which is connected to the first output end, the second output end and the control unit; the power supply unit includes a power chip, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor, the second capacitor is connected in parallel between the first output end and the second output end and in parallel between the first power input end of the power chip and the second power input end of the power chip, the third capacitor, the fourth capacitor and the fifth capacitor are all connected in parallel between the power output end of the power chip and the ground end of the power chip, and the power output end of the power chip is connected to the control unit.

[0021] In the present application, the power supply unit is connected to the control unit and is used to provide an operating voltage to the control unit.

[0022] In one embodiment, the power factor adjustment circuit also includes an over-temperature protection circuit, which is connected to the enable end of the control unit and is used to send an enable signal or a disable signal to the enable end; the over-temperature protection circuit includes a thermal sensor chip, a temperature setting resistor, a sixth capacitor and a seventh capacitor, the first end of the thermal sensor chip is connected to the first end of the temperature setting resistor and the first end of the sixth capacitor, the second end of the thermal sensor chip is connected to the first end of the seventh capacitor, the second end of the temperature setting resistor, the second end of the sixth capacitor and the second end of the seventh capacitor are grounded, and the third end of the thermal sensor chip is connected to the enable end of the control unit.

[0023] In the over-temperature protection circuit, the protection temperature in the thermal sensor chip can be set by the temperature setting resistor. If the current temperature does not exceed the set protection temperature, the third end of the over-temperature protection circuit outputs an enable signal to keep the control unit working. If the current temperature exceeds the set protection temperature, the third end of the over-temperature protection circuit outputs a disable signal to stop the control unit from working, thereby achieving the effect of over-temperature protection.

[0024] In one implementation, the first sampling unit further includes: an eighth capacitor and a ninth capacitor, wherein a first end of the eighth capacitor is connected to a second end of the first resistor, a first end of the ninth capacitor is connected to a first end of the fourth resistor, and a second end of the eighth capacitor and a second end of the ninth capacitor are grounded.

[0025] In the present application, the circuit performance can be optimized by setting the eighth capacitor and the ninth capacitor.

[0026] In one embodiment, the power factor adjustment circuit also includes an undervoltage protection circuit, which is connected to the enable end of the control unit and is used to send an enable signal or a disable signal to the enable end; the undervoltage protection circuit includes a voltage comparison chip, an eighteenth resistor, a nineteenth resistor and a twentieth resistor, the first end of the eighteenth resistor is connected to the second end of the third resistor, the second end of the eighteenth resistor is connected to the first end of the voltage comparison chip, the first end of the nineteenth resistor is connected to the second end of the sixth resistor, the second end of the nineteenth resistor is connected to the second end of the voltage comparison chip, the first end of the twentieth resistor is connected to the second end of the voltage comparison chip, the third end of the voltage comparison chip is connected to the enable end of the control unit, and the second end of the twentieth resistor is grounded.

[0027] When the input voltage is lower than the set threshold, the undervoltage protection circuit outputs a disable signal to stop the control unit from working.

[0028] In one implementation, the power factor adjustment circuit further includes a filter circuit, and the filter circuit is connected between the first input terminal and the second input terminal.

[0029] In one embodiment, the power factor adjustment circuit also includes a first inductor and a third diode, the first inductor is connected between the first input end and the first end of the first switch tube, the anode of the third diode is connected to the first end of the first switch tube, and the cathode of the third diode is connected to the first output end. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the structure of a power factor adjustment circuit provided in an embodiment of the present application;

[0032] Figure 2 A specific circuit diagram of a power factor adjustment circuit provided in an embodiment of the present application;

[0033] Figure 3 A specific circuit diagram of a power supply unit provided in an embodiment of the present application;

[0034] Figure 4 A specific circuit diagram of the over-temperature protection circuit provided in an embodiment of the present application;

[0035] Figure 5 A specific circuit diagram of the undervoltage protection circuit provided in an embodiment of the present application.

[0036] Icon: 110 - positive voltage line; 120 - negative voltage line; M1 - first switch tube; 130 - first sampling unit; 140 - second sampling unit; 150 - third sampling unit; 160 - control unit. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0038] Figure 1 For a schematic diagram of the structure of the power factor adjustment circuit for aircraft provided in the embodiment of the present application, please refer to Figure 1 The power factor adjustment circuit includes: a positive voltage line 110, a negative voltage line 120, a first switch tube M1, a first sampling unit 130, a second sampling unit 140, a third sampling unit 150 and a control unit 160. The positive voltage line 110 includes a first input terminal IN1 and a first output terminal OUT1, and the negative voltage line 120 includes a second input terminal IN2 and a second output terminal OUT2.

[0039] The first end of the first switch tube M1 is connected to the first output end OUT1 of the positive voltage line 110, and the second end of the first switch tube M1 is connected to the second output end OUT2 of the negative voltage line 120. The first switch tube M1 may be an N-type MOS tube, and the control unit 160 may control the on-off between the source and the drain in the MOS tube by changing the voltage applied to the gate of the MOS tube.

[0040] The first sampling unit 130 is connected to the first input terminal IN1 for collecting input voltage information. The second sampling unit 140 is connected to the first output terminal OUT1 for collecting output voltage information. The third sampling unit 150 is connected to the second input terminal IN2 for collecting input current information.

[0041] The control unit 160 is connected to the control end of the first switch tube M1, the first sampling unit 130, the second sampling unit 140 and the third sampling unit 150 respectively, and is used to adjust the output voltage according to the input information of the first sampling unit 130, the second sampling unit 140 and the third sampling unit 150, so as to control the conduction and cutoff of the first switch tube M1.

[0042] Figure 2 A specific circuit diagram of the power factor adjustment circuit in this embodiment is shown. Figure 2 The first sampling unit 130 includes a first resistor R38, a second resistor R37, a third resistor R42, a fourth resistor R41, a fifth resistor R35, a sixth resistor R31 and a first capacitor C34, a first end of the first resistor R38 is respectively connected to the first input end and the first end of the second resistor R37, a second end of the first resistor R38 is connected to the first end of the third resistor R42, a second end of the third resistor R42 is respectively connected to the first end of the fourth resistor R41 and the control unit 160, a second end of the second resistor R37 is respectively connected to the first end of the fifth resistor R35 and the first end of the sixth resistor R31, a second end of the sixth resistor R31 is connected to the control unit 160, a first end of the first capacitor C34 is connected to the second end of the second resistor R37, and a second end of the fourth resistor R41, a second end of the fifth resistor R35 and a second end of the first capacitor C34 are all grounded.

[0043] In one embodiment, the control unit 160 includes a power factor correction chip, that is, Figure 2The chip U7 in the power factor correction chip can be any type of active power factor correction chip, such as UC3852, UC3854, UC3855, MC34261 and other models. Taking UC3854 as an example, the power factor correction chip includes 16 pins, namely GND, PKLMT, CA_O, ISENSE, MU_O, I_AC, VA_O, V_RMS, V_REF, ENA, V_SEN, RES, SS, CT, VCC, GT_D. The specific function of each pin can be referred to its chip manual, which will not be repeated here.

[0044] In the first sampling unit 130 , the second end of the third resistor R42 is respectively connected to the first end of the fourth resistor R41 and the V_RMS pin of the power factor correction chip in the control unit 160 , and the second end of the sixth resistor R31 is connected to the V_REF pin of the power factor correction chip in the control unit 160 .

[0045] The power factor adjustment circuit provided in this embodiment can continuously adjust the input current waveform to make it close to a sine wave and keep it in phase with the input voltage by using the control unit to properly control the circuit, thereby greatly improving the power factor. On the other hand, the first capacitor C34 is set in the first sampling unit, which can effectively improve the harmonic distortion and reduce the waveform distortion of the input current. The first capacitor C34 is connected to the sampling loop of the input voltage. After the first capacitor C34 is set, it can delay the input voltage, thereby affecting the detection of the input voltage by the control unit, indirectly controlling the output of the power factor correction chip, and further improving the waveform of the input current and the phase difference between the input voltage and the input current.

[0046] Optionally, the second sampling unit 140 includes a seventh resistor R2, at least one eighth resistor and a ninth resistor R27, the first end of the seventh resistor R2 is connected to the second output end, the second end of the seventh resistor R2 is connected to the first end of at least one eighth resistor and the first end of the ninth resistor R27, respectively, the second end of at least one eighth resistor is connected to the first output end, and the first end and the second end of the ninth resistor R27 are both connected to the control unit 160. Figure 2 In the embodiment, at least one eighth resistor includes a resistor R3 and a resistor R4, and the resistor R3 and the resistor R4 are connected in series to each other.

[0047] In the second sampling unit 140, the first end of the ninth resistor R27 is connected to the V_SEN pin of the power factor correction chip in the control unit 160, and the second end of the ninth resistor R27 is connected to the VA_O pin of the power factor correction chip in the control unit 160. Optionally, the second sampling unit 140 further includes a capacitor C33, wherein the capacitor C33 is connected in parallel to both ends of the ninth resistor R27, and the circuit performance can be optimized by setting the capacitor C33.

[0048] Optionally, the third sampling unit 150 includes a tenth resistor R1, an eleventh resistor R30, a twelfth resistor R26, a thirteenth resistor R28 and a fourteenth resistor R36, the tenth resistor R1 is connected in series between the second input terminal and the second output terminal, the first end of the eleventh resistor R30 is connected to the second input terminal, the second end of the eleventh resistor R30 is connected to the control unit 160, the first end of the twelfth resistor R26 is connected to the second output terminal, the second end of the twelfth resistor R26 is connected to the first end of the thirteenth resistor R28, the second end of the thirteenth resistor R28 is respectively connected to the control unit 160 and the first end of the fourteenth resistor R36, and the second end of the fourteenth resistor R36 is connected to the control unit 160.

[0049] In the third sampling unit 150, the second end of the eleventh resistor R30 is connected to the MU_O pin of the power factor correction chip in the control unit 160, the second end of the thirteenth resistor R28 is connected to the ISENSE pin of the power factor correction chip in the control unit 160, and the second end of the fourteenth resistor R36 is connected to the CA_O pin of the power factor correction chip in the control unit 160. Optionally, the third sampling unit 150 also includes a capacitor C29, which is connected in parallel between the second input terminal and the second end of the twelfth resistor R30. The third sampling unit 150 also includes a resistor R29, a resistor R40 and a capacitor C30, the first end of the resistor R29 is connected to the second input terminal, the second end of the resistor R29 is respectively connected to the first end of the capacitor C30 and the first end of the resistor R40, the second end of the capacitor C30 is grounded, the second end of the resistor R29 is connected to the PKLMT pin of the power factor correction chip in the control unit 160, and the second end of the resistor R40 is connected to the V_REF pin of the power factor correction chip in the control unit 160.

[0050] Optionally, the control unit 160 also includes an output unit, which is respectively connected to the control unit 160 and the control end of the first switch tube M1; the output unit includes a fifteenth resistor R24, a sixteenth resistor R23, a seventeenth resistor R25, a first diode D9 and a second diode D10, the first end of the fifteenth resistor R24 ​​and the first end of the sixteenth resistor R23 are connected to the control end of the first switch tube M1, the second end of the fifteenth resistor R24 ​​is connected to the second output end, the anode of the first diode D9 is connected to the first end of the sixteenth resistor R23, the cathode of the first diode D9 is connected to the second end of the sixteenth resistor R23, the first end of the seventeenth resistor R25 and the cathode of the second diode D10, the second end of the seventeenth resistor R25 is connected to the control unit 160, and the anode of the second diode D10 is grounded.

[0051] In the output unit, the second end of the seventeenth resistor R25 is connected to the GT_D pin of the power factor correction chip in the control unit 160, and the GT_D pin is the driving output end of the power factor correction chip. The power factor correction chip applies a voltage to the gate of the first switch tube M1 through the output unit to control the on and off of the first switch tube M1. Figure 2 As shown, when the GT_D pin outputs a high-level signal, the first switch tube M1 is turned on, and when the GT_D pin outputs a low-level signal, the first switch tube M1 is turned off. The power factor correction chip controls the duration of the on and off of the first switch tube M1 by adjusting the duty cycle of the output signal of the GT_D pin.

[0052] Optionally, the power factor adjustment circuit further includes a power supply unit, which is respectively connected to the first output end, the second output end and the control unit. Figure 3 A specific circuit diagram of the power supply unit is shown in FIG. Figure 3 The power supply unit includes a power chip U10, a second capacitor C28, a third capacitor C45, a fourth capacitor C35 and a fifth capacitor C56. The second capacitor C28 is connected in parallel between the first output terminal and the second output terminal and in parallel between the first power input terminal of the power chip U10 and the second power input terminal of the power chip. Specifically, the first end of the second capacitor C28 is connected to the first output terminal and the first power input terminal (VCAP+) of the power chip, and the second end of the second capacitor C28 is connected to the second output terminal and the second power input terminal (VCAP-) of the power chip. The third capacitor C45, the fourth capacitor C35 and the fifth capacitor C56 are all connected in parallel between the power output terminal (OUT+) of the power chip and the ground terminal (0V) of the power chip, the ground terminal of the power chip is connected to the ground (PFC_GND), and the power output terminal (OUT+) of the power chip is connected to the control unit 160. Specifically, the power output terminal (OUT+) is connected to the VCC pin of the power factor correction chip to provide a 12V power supply voltage to the power factor correction chip.

[0053] Optionally, the power factor adjustment circuit further includes an over-temperature protection circuit, which is connected to an enable terminal of the control unit and is used to send an enable signal or a disable signal to the enable terminal. Figure 4 A specific circuit diagram of the over-temperature protection circuit is shown in Figure 4The over-temperature protection circuit includes a thermal sensor chip U9, a temperature setting resistor R47, a sixth capacitor C55, and a seventh capacitor C54. The first end (Tset pin) of the thermal sensor chip is connected to the first end of the temperature setting resistor R47 and the first end of the sixth capacitor C55. The second end (Vtemp pin) of the thermal sensor chip is connected to the first end of the seventh capacitor C54. The second end of the temperature setting resistor R47, the second end of the sixth capacitor C55, and the second end of the seventh capacitor C54 are grounded. The third end (OUT pin) of the thermal sensor chip is connected to the enable end of the control unit 160. Specifically, the OUT pin of the thermal sensor chip is connected to the ENA pin of the power factor correction chip.

[0054] In the over-temperature protection circuit, the protection temperature in the thermal sensor chip can be set by the temperature setting resistor R47. If the current temperature does not exceed the set protection temperature, the OUT pin of the over-temperature protection circuit outputs an enable signal (for example, outputs a high-level signal) to keep the power factor correction chip working. If the current temperature exceeds the set protection temperature, the OUT pin of the over-temperature protection circuit outputs a disable signal (for example, outputs a low-level signal) to stop the power factor correction chip from working, thereby achieving the effect of over-temperature protection. Figure 4 As shown, when the current temperature exceeds 86°C, the power factor correction chip will stop working.

[0055] Optionally, the power factor adjustment circuit further includes an undervoltage protection circuit, which is connected to an enable terminal of the control unit and is used to send an enable signal or a disable signal to the enable terminal. Figure 5 A specific circuit diagram of the undervoltage protection circuit is shown in Figure 5 The undervoltage protection circuit includes a voltage comparison chip U8, an eighteenth resistor R44, a nineteenth resistor R45 and a twentieth resistor R46. The first end of the eighteenth resistor R44 is connected to the second end of the third resistor R42, the second end of the eighteenth resistor R44 is connected to the first end (IN+ pin) of the voltage comparison chip, the first end of the nineteenth resistor R45 is connected to the second end of the sixth resistor R31, the second end of the nineteenth resistor R45 is connected to the second end (IN- pin) of the voltage comparison chip, the first end of the twentieth resistor R46 is connected to the second end of the voltage comparison chip, and the second end of the twentieth resistor R46 is grounded. The third end (OUT pin) of the voltage comparison chip is connected to the ENA pin of the power factor correction chip. When the input voltage is lower than the set threshold, the OUT pin of the voltage comparison chip outputs a disable signal to stop the power factor correction chip from working.

[0056] In the over-temperature protection circuit, the fourth end (power input end, V+ pin) of the thermal sensor chip is connected to the power output end of the power chip in the power supply unit; in the under-voltage protection circuit, the fourth end (power input end, V+ pin) of the voltage comparison chip is connected to the power output end of the power chip in the power supply unit. While the power supply unit provides a 12V power supply voltage to the power factor correction chip, it also provides a 12V power supply voltage to the thermal sensor chip and the voltage comparison chip, thereby realizing power supply to the control unit 160, the over-temperature protection circuit and the under-voltage protection circuit.

[0057] Optional, such as Figure 2 As shown, the first sampling unit 130 further includes: an eighth capacitor C42 and a ninth capacitor C31, the first end of the eighth capacitor C42 is connected to the second end of the first resistor R38, the first end of the ninth capacitor C31 is connected to the first end of the fourth resistor R41, and the second end of the eighth capacitor C42 and the second end of the ninth capacitor C31 are grounded. By setting the eighth capacitor C42 and the ninth capacitor C31, the circuit performance can be optimized.

[0058] Optional, such as Figure 2 As shown, the power factor adjustment circuit also includes a filter circuit, and the filter circuit is connected between the first input terminal and the second input terminal. Figure 2 In the filter circuit, the filter circuit includes: a capacitor C2, a capacitor C3 and a capacitor C4 connected in parallel with each other.

[0059] In practical applications, the previous stage circuit of the power factor adjustment circuit is generally a rectifier circuit. The current waveform output from the output end of the rectifier circuit is relatively poor, with serious harmonic phenomena, and the input voltage and input current are not synchronized, and there is a phase difference. This phenomenon can be greatly improved through the power factor adjustment circuit. At the same time, the filter circuit set at the front end can filter the input voltage, which plays a preliminary improvement role.

[0060] Optionally, the power factor adjustment circuit also includes a first inductor L4 and a third diode D1, the first inductor L4 is connected between the first input end and the first end of the first switch tube M1, the anode of the third diode D1 is connected to the first end of the first switch tube M1, and the cathode of the third diode D1 is connected to the first output end.

[0061] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0062] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A power factor adjustment circuit for aircraft, characterized in that: include: A positive voltage line including a first input terminal and a first output terminal; A negative voltage line including a second input terminal and a second output terminal; A first switch tube, a first end of which is connected to the first output end of the positive voltage line, and a second end of which is connected to the second output end of the negative voltage line; A first sampling unit, connected to the first input terminal, for collecting input voltage information; a second sampling unit connected to the first output terminal for collecting output voltage information; a third sampling unit connected to the second input terminal for collecting input current information; a control unit, which is connected to the control end of the first switch tube, the first sampling unit, the second sampling unit and the third sampling unit respectively, and is used to control the conduction and cutoff of the first switch tube according to input information of the first sampling unit, the second sampling unit and the third sampling unit; Wherein, the first sampling unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a first capacitor, a first end of the first resistor is respectively connected to the first input end and the first end of the second resistor, a second end of the first resistor is connected to the first end of the third resistor, a second end of the third resistor is respectively connected to the first end of the fourth resistor and the control unit, a second end of the second resistor is respectively connected to the first end of the fifth resistor and the first end of the sixth resistor, a second end of the sixth resistor is connected to the control unit, a first end of the first capacitor is connected to the second end of the second resistor, and a second end of the fourth resistor, a second end of the fifth resistor and a second end of the first capacitor are all grounded; The second sampling unit includes a seventh resistor, at least one eighth resistor and a ninth resistor, the first end of the seventh resistor is connected to the second output end, the second end of the seventh resistor is connected to the first end of the at least one eighth resistor and the first end of the ninth resistor respectively, the second end of the at least one eighth resistor is connected to the first output end, and the first end and the second end of the ninth resistor are both connected to the control unit; The third sampling unit includes a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor, the tenth resistor is connected in series between the second input terminal and the second output terminal, the first end of the eleventh resistor is connected to the second input terminal, the second end of the eleventh resistor is connected to the control unit, the first end of the twelfth resistor is connected to the second output terminal, the second end of the twelfth resistor is connected to the first end of the thirteenth resistor, the second end of the thirteenth resistor is connected to the control unit and the first end of the fourteenth resistor respectively, and the second end of the fourteenth resistor is connected to the control unit; The control unit also includes an output unit, which is respectively connected to the control unit and the control end of the first switch tube; the output unit includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a first diode and a second diode, the first end of the fifteenth resistor and the first end of the sixteenth resistor are connected to the control end of the first switch tube, the second end of the fifteenth resistor is connected to the second output end, the anode of the first diode is connected to the first end of the sixteenth resistor, the cathode of the first diode is connected to the second end of the sixteenth resistor, the first end of the seventeenth resistor and the cathode of the second diode, the second end of the seventeenth resistor is connected to the control unit, and the anode of the second diode is grounded.

2. The power factor adjustment circuit according to claim 1, characterized in that: The power factor adjustment circuit also includes a power supply unit, which is connected to the first output end, the second output end and the control unit; the power supply unit includes a power chip, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor, the second capacitor is connected in parallel between the first output end and the second output end and in parallel between the first power input end of the power chip and the second power input end of the power chip, the third capacitor, the fourth capacitor and the fifth capacitor are all connected in parallel between the power output end of the power chip and the ground end of the power chip, and the power output end of the power chip is connected to the control unit.

3. The power factor adjustment circuit according to claim 1, characterized in that: The power factor adjustment circuit also includes an over-temperature protection circuit, which is connected to the enable end of the control unit and is used to send an enable signal or a disable signal to the enable end; the over-temperature protection circuit includes a thermal sensor chip, a temperature setting resistor, a sixth capacitor and a seventh capacitor, a first end of the thermal sensor chip is connected to the first end of the temperature setting resistor and the first end of the sixth capacitor, a second end of the thermal sensor chip is connected to the first end of the seventh capacitor, a second end of the temperature setting resistor, a second end of the sixth capacitor and a second end of the seventh capacitor are grounded, and a third end of the thermal sensor chip is connected to the enable end of the control unit.

4. The power factor adjustment circuit according to claim 1, characterized in that: The first sampling unit also includes: an eighth capacitor and a ninth capacitor, wherein a first end of the eighth capacitor is connected to a second end of the first resistor, a first end of the ninth capacitor is connected to a first end of the fourth resistor, and second ends of the eighth capacitor and the ninth capacitor are grounded.

5. The power factor adjustment circuit according to claim 1, characterized in that: The power factor adjustment circuit also includes an undervoltage protection circuit, which is connected to the enable end of the control unit and is used to send an enable signal or a disable signal to the enable end; the undervoltage protection circuit includes a voltage comparison chip, an eighteenth resistor, a nineteenth resistor and a twentieth resistor, the first end of the eighteenth resistor is connected to the second end of the third resistor, the second end of the eighteenth resistor is connected to the first end of the voltage comparison chip, the first end of the nineteenth resistor is connected to the second end of the sixth resistor, the second end of the nineteenth resistor is connected to the second end of the voltage comparison chip, the first end of the twentieth resistor is connected to the second end of the voltage comparison chip, the third end of the voltage comparison chip is connected to the enable end of the control unit, and the second end of the twentieth resistor is grounded.

6. The power factor adjustment circuit according to claim 1, characterized in that: The power factor adjustment circuit further includes a filter circuit connected between the first input terminal and the second input terminal.

7. The power factor adjustment circuit according to claim 1, characterized in that: The power factor adjustment circuit also includes a first inductor and a third diode, the first inductor is connected between the first input end and the first end of the first switch tube, the anode of the third diode is connected to the first end of the first switch tube, and the cathode of the third diode is connected to the first output end.

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