A power supply circuit for suppressing instantaneous inrush current during power-on.

Abstract

The present invention discloses a power supply circuit for suppressing instantaneous inrush current at startup, comprising an input protection module, a rectifier filter module, a startup module and an output module; the input protection module is respectively connected to the rectifier filter module and the startup module, and the output module is respectively connected to the rectifier filter module and the startup module; the rectifier filter module is connected in series with a first thermistor, a self-locking circuit is connected in parallel at both ends of the first thermistor, and the self-locking circuit is connected to the startup module, and when the output module outputs normally, the startup module controls the self-locking circuit to be turned on, thereby short-circuiting the first thermistor. The setting of the first thermistor can suppress instantaneous inrush current at startup; after the first thermistor is short-circuited by the setting of the self-locking circuit, the loss caused by the existence of the first thermistor can be avoided, thereby improving the power supply efficiency; at the same time, the problem of high inrush current at startup caused by the small resistance value of the first thermistor is avoided, thereby preventing product damage.

Description

Technical Field

[0001] The invention belongs to the technical field of power supply circuits, and in particular relates to a switching power supply circuit capable of suppressing instantaneous inrush current when the power is turned on. Background Art

[0002] The power supply circuit refers to the circuit design of the power supply part that provides power supply to electrical equipment. It can be divided into switching power supply circuit, voltage-stabilized power supply circuit, current-stabilized power supply circuit, power power supply circuit, inverter power supply circuit, DC-DC power supply circuit, protection power supply circuit, etc.

[0003] With the continuous development of science and technology, electronic products are becoming more and more popular, and more and more devices are powered by switching power supplies. However, in order to smooth the voltage and ripple after input rectification, large-capacity high-voltage capacitors are generally used in the power supply to play a role in smoothing and filtering. For example, a 60W power supply generally uses a 100U / 400V capacitor, but at the moment of power on, the capacitor needs to be charged, which can be equivalent to a direct short circuit, so an impact current of about 100A will be generated. If a family uses several electrical appliances at the same time, the family switch will be frequently disconnected, which will cause serious damage to the equipment. Therefore, most of the current adapter power supplies add a thermistor NTC101 (such as Figure 1 As shown in the figure, the negative temperature coefficient thermistor NTC101 is used to reduce the inrush current. When the switching power supply is started for the first time, the resistance of NTC101 is very large, which can limit the inrush current. As the NTC101 itself heats up, its resistance value becomes smaller, reducing its power consumption during operation.

[0004] Therefore, although the addition of thermistor NTC101 suppresses the input current when the power is turned on, it is always present during operation, so serious losses will occur. In addition to reducing the service life of the product, the product cannot meet the energy efficiency certification standards due to the increasingly high efficiency requirements of the product. For example, it is difficult to meet the European energy efficiency VI. At the same time, because the thermistor has a lower resistance value as the temperature increases, if the power is turned off and then turned on again when the temperature rises, the impact current will become very large, causing damage to the power supply product.

[0005] As disclosed in the patent application with application number 201220392885.0, a suppression circuit for instantaneous starting current is connected to a power supply at one end and to a neutral line connected to a load at the other end. The suppression circuit includes a relay, a current limiting resistor, a thyristor-driven photocoupler, a thermistor and a capacitor. The thyristor-driven photocoupler and the thermistor are connected in series and then connected in parallel with the relay and the current limiting resistor respectively, and then connected to the positive electrode of the capacitor, and the negative electrode of the capacitor is connected to the neutral line.

[0006] However, although the thermistor used in the instantaneous starting current suppression circuit disclosed above suppresses the inrush current when the power is turned on, it always exists during operation, so serious losses will occur. At the same time, because the thermistor has a lower resistance value as the temperature increases, if the power is turned off and then turned on again when the temperature rises, the inrush current will become very large, thereby causing damage to the power supply product. Summary of the invention

[0007] In order to solve the above problems, the primary purpose of the present invention is to provide a power supply circuit that can suppress the instantaneous inrush current during startup. While being able to suppress the instantaneous inrush current during startup, it can avoid the loss caused by the presence of thermistors, thereby improving power supply efficiency and meeting current energy efficiency requirements.

[0008] Another object of the present invention is to provide a power supply circuit that suppresses the instantaneous surge current when the power is turned on, so that the surge current does not increase when the power is turned on due to the decrease in the resistance of the thermistor, thereby avoiding damage to the product or power supply equipment.

[0009] To achieve the above object, the technical solution of the present invention is as follows:

[0010] A power supply circuit for suppressing instantaneous inrush current at startup, comprising an input protection module, a rectifier and filter module, a startup module and an output module; the input protection module is connected to the rectifier and filter module and the startup module respectively, the output module is provided with a first input end and a second input end, the first input end and the second input end are connected to the rectifier and filter module and the startup module respectively;

[0011] The input protection module is used to input an AC voltage. After the AC voltage passes through the rectification and filtering module, a stable DC voltage is formed and input to the first input terminal of the output module. A voltage dividing module is also provided between the input protection module and the starting module. The AC voltage input through the input protection module is divided by the voltage dividing module to form a starting voltage of the starting module. After the starting module is started, the second input terminal of the output module is turned on, so that the output module works normally and the current output is realized;

[0012] The rectifier and filter module is connected in series with a first thermistor, and a self-locking circuit is connected in parallel at both ends of the first thermistor, and the self-locking circuit is connected to the startup module. When the output module outputs normally, the startup module controls the self-locking circuit to be turned on, thereby short-circuiting the first thermistor. In the present invention, the setting of the first thermistor can suppress the instantaneous inrush current when the power is turned on. At the same time, after the first thermistor is short-circuited by the setting of the self-locking circuit, the power supply circuit can achieve unlimited current resistance during normal operation, avoiding the loss caused by the existence of the first thermistor, thereby improving the power supply efficiency and meeting the current energy efficiency requirements; and there will be no problem of high inrush current when the power is turned on due to the decrease in the resistance value of the first thermistor, thereby avoiding damage to the product or power supply equipment.

[0013] Furthermore, the output module is also provided with a transformer and a power supply output end for outputting current, the transformer includes a first primary side, a second primary side and a secondary side, the secondary side is connected to the power supply output end, one end of the first primary side of the transformer is connected to the rectification and filtering module, the other end of the first primary side of the transformer is connected to the starting module, one end of the second primary side of the transformer is connected to the starting module, and the other end of the second primary side of the transformer is grounded; the AC voltage input by the input protection module forms a stable DC voltage after passing through the rectification and filtering module and is input to one end of the first primary side of the transformer, the AC voltage input by the input protection module is divided by the voltage divider module to form a starting voltage of the starting module, and after the starting module is started, the other end of the first primary side of the transformer is turned on, so that the output module works normally and the current is output through the power supply output end; the end of the first primary side of the transformer connected to the rectification and filtering module is the first input end of the output module, and the end of the first primary side of the transformer connected to the starting module is the second input end of the output module.

[0014] Further, the self-locking circuit includes a linear voltage stabilizing unit, a first voltage dividing unit, a second voltage dividing unit, a self-locking unit and a first MOS tube, one end of the linear voltage stabilizing unit is connected to the startup module, the other end of the linear voltage stabilizing unit is connected to the self-locking unit through the first voltage dividing unit, the self-locking unit is connected to the output end of the rectifier and filter module through the second voltage dividing unit, the gate of the first MOS tube is connected to the self-locking unit, the source and drain of the first MOS tube are respectively connected to the two ends of the first thermistor, and the source of the first MOS tube is grounded; when the startup module is started, the linear voltage stabilizing unit is turned on, the voltage output by the linear voltage stabilizing unit passes through the first voltage dividing unit to turn on the self-locking unit, and after the self-locking unit is turned on, the voltage output by the rectifier and filter module is divided by the second voltage dividing unit and then supplied to the gate of the first MOS tube through the self-locking unit, thereby turning on the first MOS tube, causing the first thermistor to short-circuit. In the present invention, by setting the above-mentioned self-locking circuit, it can be achieved that after the first MOS tube is turned on, it is equivalent to a thermistor short circuit, so that the first thermistor used for current limiting will not be turned on for a long time. When the power is turned on normally, it is turned on by the first MOS tube to form a short circuit state, so no heat energy and loss are generated, which can greatly improve the conversion efficiency of the product and meet the current energy efficiency requirements; at the same time, the problem of increasing the impact current when starting up due to the decrease in the resistance value of the first thermistor will not occur, thereby avoiding damage to the product or power supply equipment.

[0015] Further, the linear voltage stabilizing unit includes a first triode, a first voltage stabilizing diode, a first electrolytic capacitor, a first capacitor, and a first resistor; the collector of the first triode is connected to the starting module, the emitter of the first triode is connected to the first voltage dividing unit, the cathode of the first voltage stabilizing diode is connected to the base of the first triode, the anode of the first voltage stabilizing diode is grounded, the positive electrode of the first electrolytic capacitor is connected to the collector of the first triode, the negative electrode of the first electrolytic capacitor is grounded, one end of the first capacitor is connected to the emitter of the first triode, the other end of the first capacitor is grounded, one end of the first resistor is connected to the base of the first triode, and the other end of the first resistor is connected to the collector of the first triode.

[0016] Further, the first voltage divider unit includes a second resistor and a third resistor, one end of the second resistor is connected to the emitter of the first transistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is grounded, and the common end between the second resistor and the third resistor is connected to the self-locking unit.

[0017] Further, the second voltage-dividing unit includes a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor, one end of the fourth resistor is connected to the output end of the rectifier and filter module, the other end of the fourth resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to one end of the seventh resistor, the other end of the seventh resistor is grounded, and the common end between the sixth resistor and the seventh resistor is connected to the self-locking unit.

[0018] Further, the self-locking unit includes a second triode, a third triode, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, and a second capacitor; the base of the second triode is connected to the common end between the second resistor and the third resistor, the emitter of the second triode is connected to one end of the eleventh resistor, the other end of the eleventh resistor is connected to the gate of the first MOS tube, the collector of the second triode is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to the base of the third triode, the emitter of the third triode is connected to the common end between the sixth resistor and the seventh resistor, the collector of the third triode is connected to one end of the tenth resistor, the other end of the tenth resistor is connected to the base of the second triode, one end of the eighth resistor is connected to the emitter of the third triode, the other end of the eighth resistor is connected to the base of the third triode, one end of the second capacitor is connected to the common end between the tenth resistor and the second triode, and the other end of the second capacitor is grounded.

[0019] Further, the rectification and filtering module includes a first rectifier bridge, a second rectifier bridge, and a second electrolytic capacitor, the input protection module includes a neutral line input end, a live line input end, a fuse and a varistor, the fuse is connected in series to the neutral line input end, one end of the varistor is connected to the neutral line input end, and the other end of the varistor is connected to the live line input end, the first rectifier bridge and the second rectifier bridge are full bridges formed by a combination of four rectifier diodes, the two AC input ends of the first rectifier bridge are connected to the neutral line input end, one of the DC output ends of the first rectifier bridge is connected to the positive electrode of the second electrolytic capacitor, the other DC output end of the first rectifier bridge is connected to one end of the first thermistor and grounded, the other end of the first thermistor is connected to the negative electrode of the second electrolytic capacitor, the two AC input ends of the second rectifier bridge are connected to the live line input end, one of the DC output ends of the second rectifier bridge is connected to the positive electrode of the second electrolytic capacitor, and the other DC output end of the second rectifier bridge is connected to one end of the first thermistor that is grounded. In the present invention, the fuse and the varistor play a protective role, the first rectifier bridge and the second rectifier bridge play a rectifying role to convert alternating current into direct current, the second electrolytic capacitor plays a filtering role, and the first thermistor plays a current limiting role to suppress the instantaneous impact current when starting up, and the fourth resistor of the self-locking circuit is connected to the positive electrode of the second electrolytic capacitor.

[0020] Further, the voltage divider module includes a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a fifteenth resistor, one end of the twelfth resistor is connected to the neutral line input terminal, the other end of the twelfth resistor is connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is connected to the live line input terminal, one end of the fourteenth resistor is connected to the common end between the twelfth resistor and the thirteenth resistor, the other end of the fourteenth resistor is connected to one end of the fifteenth resistor, and the other end of the fifteenth resistor is connected to the starting module.

[0021] Further, the startup module includes a first control chip, a second MOS tube, a second thermistor, a first diode, a second diode, a third diode, a fourth diode, a third electrolytic capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a twenty-third resistor, and a twenty-fourth resistor. The model of the first control chip is OB2273, and the first control chip includes a GND pin, an FB pin, a PRT pin, a GATE pin, a VDD pin, and a SENSE pin;

[0022] The GND pin of the first control chip is grounded; the anode of the fourth diode is connected to the PRT pin of the first control chip, the cathode of the fourth diode is connected to one end of the second thermistor, the other end of the second thermistor is connected to one end of the twenty-third resistor, and the other end of the twenty-third resistor is grounded; the GATE pin of the first control chip is connected to one end of the sixteenth resistor, the other end of the sixteenth resistor is connected to one end of the twentieth resistor, the other end of the twentieth resistor is connected to one end of the twenty-fourth resistor, the other end of the twenty-fourth resistor is connected to one end of the seventeenth resistor, and the other end of the seventeenth resistor is grounded; the cathode of the third diode is connected to the common end between the sixteenth resistor and the twentieth resistor, the anode of the third diode is connected to the common end of the twentieth resistor and the twenty-fourth resistor, the gate of the second MOS tube is connected to the anode of the third diode, the source of the second MOS tube is connected to the common end of the twenty-fourth resistor and the seventeenth resistor, the end of the first primary side of the transformer connected to the startup module is connected to the drain of the second MOS tube, one end of the sixth capacitor is connected to the source of the second MOS tube, and the other end of the sixth capacitor is connected to the drain of the second MOS tube;

[0023] The VDD pin of the first control chip is connected to one end of the twenty-first resistor, the other end of the twenty-first resistor is connected to the cathode of the second diode, the anode of the second diode is connected to the cathode of the first diode, the anode of the first diode is connected to one end of the twenty-second resistor, the other end of the twenty-second resistor is connected to one end of the second primary side of the transformer of the output module, the other end of the second primary side of the transformer is grounded, the common end of the twenty-first resistor and the second diode is connected to the fifteenth resistor of the voltage divider module, the two ends of the fifth capacitor are connected in parallel to the two ends of the first diode, one end of the fourth capacitor is connected to the common end between the fifteenth resistor and the VDD pin of the first control chip, the other end of the fourth capacitor is connected to the negative electrode of the third electrolytic capacitor, the positive electrode of the third electrolytic capacitor is connected to the common end between the first diode and the second diode, and the common end between the fourth capacitor and the third electrolytic capacitor is grounded, and the collector of the first transistor of the self-locking circuit is connected to the common end between the first diode and the second diode;

[0024] The SENSE pin of the first control chip is connected to one end of the third capacitor, the other end of the third capacitor is grounded, one end of the nineteenth resistor is connected to the common end between the SENSE pin of the first control chip and the third capacitor, and the other end of the nineteenth resistor is connected to the common end between the seventeenth resistor and the twenty-fourth resistor;

[0025] One end of the eighteenth resistor is connected to the PRT pin of the first control chip and the common end of the first diode, and the other end of the eighteenth resistor is connected to the positive electrode of the third electrolytic capacitor.

[0026] Further, the power output end includes a positive output end and a negative output end, the output module also includes a second control chip, a third MOS tube, a fourth electrolytic capacitor, a seventh capacitor, an eighth capacitor, a twenty-fifth resistor, a twenty-sixth resistor, a twenty-seventh resistor, a twenty-eighth resistor, and a twenty-ninth resistor, and the second control chip includes a VG pin, a VSS pin, an HVC pin, a VD pin, a SLEW pin, and a VDD pin;

[0027] The VG pin of the second control chip is connected to the gate of the third MOS tube, the source of the third MOS tube is connected to one end of the secondary side of the transformer, the other end of the secondary side of the transformer is connected to a feedback module, the feedback module is connected to the FB pin of the first control chip, the source of the third MOS tube is connected to one end of the twenty-eighth resistor, the other end of the twenty-eighth resistor is connected to the VD pin of the second control chip, the VSS pin of the second control chip is connected to the source of the third MOS tube, the HVC pin of the second control chip is connected to the VSS pin of the second control chip, the SLEW of the second control chip is connected to one end of the twenty-ninth resistor, the other end of the twenty-ninth resistor is connected to one end of the eighth capacitor, and the eighth capacitor The other end of the twenty-fifth resistor is connected to the VDD pin of the second control chip, the common end of the twenty-ninth resistor and the eighth capacitor is connected to the source of the third MOS tube, one end of the twenty-sixth resistor is connected to the source of the third MOS tube, the other end of the twenty-sixth resistor is connected to one end of the seventh capacitor, the other end of the seventh capacitor is connected to the positive electrode of the fourth electrolytic capacitor, the positive electrode of the fourth electrolytic capacitor is connected to the positive output end, the negative electrode of the fourth electrolytic capacitor is connected to the negative output end, the two ends of the twenty-fifth resistor are connected in parallel to the two ends of the fourth electrolytic capacitor, one end of the twenty-seventh resistor is connected to the common end between the twenty-sixth resistor and the source of the third MOS tube, and the other end of the twenty-seventh resistor is connected to the common end between the twenty-sixth resistor and the seventh capacitor.

[0028] Further, the feedback module includes a first photocoupler, a second voltage-stabilizing diode, a ninth capacitor, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, a thirtieth resistor, a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, and a thirty-sixth resistor, and the first photocoupler includes a light-emitting diode and a phototransistor;

[0029] The emitter of the phototransistor is grounded, the collector of the phototransistor is connected to one end of the 30th resistor, the other end of the 30th resistor is connected to one end of the ninth capacitor, the other end of the ninth capacitor is connected to one end of the tenth capacitor, the other end of the tenth capacitor is connected to the emitter of the phototransistor, and the common end between the 30th resistor and the ninth capacitor is connected to the FB pin of the first control chip;

[0030] The cathode of the light-emitting diode is connected to the cathode of the second voltage-stabilizing diode, the anode of the second voltage-stabilizing diode is connected to one end of the thirty-fifth resistor, the other end of the thirty-fifth resistor is connected to the cathode of the second voltage-stabilizing diode, the end of the secondary side of the transformer connected to the feedback module is connected to the common end between the anode of the second voltage-stabilizing diode and the thirty-fifth resistor, one end of the thirty-first resistor is connected to the anode of the light-emitting diode, the other end of the thirty-first resistor is connected to one end of the thirty-fourth resistor, the other end of the thirty-fourth resistor is connected to one end of the thirty-sixth resistor, and the other end of the thirty-sixth resistor is connected to the second voltage-stabilizing diode. The anode of the tube is connected to the common end between the thirty-fifth resistor, the two ends of the thirty-second resistor are connected in parallel to the two ends of the light-emitting diode, one end of the thirty-third resistor is connected to the common end between the cathode of the second voltage-stabilizing diode and the cathode of the light-emitting diode, the other end of the thirty-third resistor is connected to one end of the eleventh capacitor, the other end of the eleventh capacitor is connected to one end of the twelfth capacitor, the other end of the twelfth capacitor is connected to the common end between the thirty-sixth resistor and the thirty-fourth resistor, the common end between the thirty-first resistor and the thirty-fourth resistor is connected to the common end between the seventh capacitor of the output module and the positive electrode of the fourth electrolytic capacitor.

[0031] The advantages of the present invention are as follows: in the present invention, the instantaneous inrush current at startup can be suppressed by setting the first thermistor; at the same time, after the first thermistor is short-circuited by setting the self-locking circuit, the power supply circuit can achieve unlimited current resistance during normal operation, thereby avoiding the loss caused by the existence of the first thermistor, thereby improving the power supply efficiency and meeting the current energy efficiency requirements; and there will be no problem of higher inrush current at startup due to the smaller resistance of the first thermistor, thereby avoiding damage to the product or power supply equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a circuit structure schematic diagram of an existing switching power supply circuit.

[0033] Figure 2 The present invention is a schematic diagram of the first circuit structure of a power supply circuit for suppressing instantaneous inrush current during startup.

[0034] Figure 3It is a schematic diagram of the second circuit structure of a power supply circuit for suppressing instantaneous inrush current at startup implemented by the present invention.

[0035] Figure 4 It is a circuit structure schematic diagram of the self-locking circuit implemented by the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] The technical solution of the present invention is as follows:

[0038] See also Figure 2-4 As shown, the present invention provides a power supply circuit for suppressing instantaneous inrush current at startup, comprising an input protection module 1, a rectifying and filtering module 2, a starting module 3 and an output module 4; the input protection module 1 is connected to the rectifying and filtering module 2 and the starting module 3 respectively, the output module 4 is provided with a first input terminal 10 and a second input terminal 20, the first input terminal 10 and the second input terminal 20 are connected to the rectifying and filtering module 2 and the starting module 3 respectively;

[0039] The input protection module 1 is used to input an AC voltage. After the AC voltage passes through the rectifier and filter module 2, a stable DC voltage is formed and input to the first input terminal 10 of the output module 4. A voltage divider module 5 is also provided between the input protection module 1 and the start-up module 3. The AC voltage input through the input protection module 1 is divided by the voltage divider module 5 to form a start-up voltage of the start-up module 3. After the start-up module 3 is started, the second input terminal 20 of the output module 4 is turned on, so that the output module 4 works normally and the current output is realized;

[0040] The rectifier and filter module 2 is connected in series with a first thermistor R1, and a self-locking circuit 6 is connected in parallel at both ends of the first thermistor R1, and the self-locking circuit 6 is connected to the start-up module 3. When the output module 4 outputs normally, the start-up module 3 controls the self-locking circuit 6 to be turned on, so that the first thermistor R1 is short-circuited. In the present invention, the setting of the first thermistor R1 can suppress the instantaneous inrush current when the power is turned on. At the same time, after the first thermistor R1 is short-circuited by the setting of the self-locking circuit 6, the power supply circuit can achieve unlimited current resistance during normal operation, avoiding the loss caused by the existence of the first thermistor R1, thereby improving the power supply efficiency and meeting the current energy efficiency requirements; and there will be no problem of high inrush current when the power is turned on due to the decrease in the resistance value of the first thermistor R1, thereby avoiding damage to the product or power supply equipment.

[0041] Among them, the output module 4 is also provided with a transformer 41 and a power supply output end for outputting current, the transformer 41 includes a first primary side 411, a second primary side 412 and a secondary side 413, the secondary side 413 is connected to the power supply output end, one end of the first primary side 411 of the transformer 41 is connected to the rectifier and filter module 2, the other end of the first primary side 411 of the transformer 41 is connected to the starting module 3, one end of the second primary side 412 of the transformer 41 is connected to the starting module 3, and the other end of the second primary side 412 of the transformer 41 is grounded; the AC voltage input by the input protection module 1 forms a stable DC voltage input to one end of the first primary side 411 of the transformer 41 after passing through the rectifier and filter module 2, and the AC voltage input through the input protection module 1 is divided by the voltage divider module 5 to form the starting voltage of the starting module 3. After the starting module 3 is started, the other end of the first primary side 411 of the transformer 41 is turned on, so that the output module 4 works normally and the current is output through the power supply output end. In the present invention, one end of the first primary side 411 of the transformer 41 connected to the rectifier and filter module is the first input end 10 of the output module, and one end of the first primary side 411 of the transformer 41 connected to the starting module is the second input end 20 of the output module. High-frequency current flows into the first primary side 411 of the transformer 41, thereby generating an induced current in the secondary side 413 of the transformer 41.

[0042] The self-locking circuit 6 includes a linear voltage stabilizing unit 61, a first voltage dividing unit 62, a second voltage dividing unit 63, a self-locking unit 64 and a first MOS tube Q101A. One end of the linear voltage stabilizing unit 61 is connected to the startup module 3, and the other end of the linear voltage stabilizing unit 61 is connected to the self-locking unit 64 through the first voltage dividing unit 62. The self-locking unit 64 is connected to the output end of the rectifier and filter module 2 through the second voltage dividing unit 63. The gate of the first MOS tube Q101A is connected to the self-locking unit 64. The source and drain of the first MOS tube Q101A are connected. The two ends of the first thermistor R1 are respectively connected, and the source of the first MOS tube Q101A is grounded; when the startup module 3 is started, the linear voltage stabilizing unit 61 is turned on, and the voltage output by the linear voltage stabilizing unit 61 passes through the first voltage dividing unit 62 to turn on the self-locking unit 64. After the self-locking unit 64 is turned on, the voltage output by the rectifier and filter module 2 is divided by the second voltage dividing unit 63 and then supplied to the gate of the first MOS tube Q101A through the self-locking unit 64, thereby turning on the first MOS tube Q101A, causing the first thermistor R1 to be short-circuited. In the present invention, by setting the above-mentioned self-locking circuit 6, it can be achieved that after the first MOS tube Q101A is turned on, it is equivalent to a thermistor short circuit, so that the first thermistor R1 used for current limiting will not be turned on for a long time. When the power is turned on normally, it is turned on by the first MOS tube Q101A to form a short circuit state, so no heat energy and loss are generated, which can greatly improve the conversion efficiency of the product and meet the current energy efficiency requirements; at the same time, the problem of increasing the impact current when starting up due to the decrease in the resistance value of the first thermistor R1 will not occur, thereby avoiding damage to the product or power supply equipment.

[0043] Among them, the linear voltage stabilizing unit 61 includes a first transistor Q402, a first voltage stabilizing diode ZD402, a first electrolytic capacitor C414, a first capacitor C408, and a first resistor R405; the collector of the first transistor Q402 is connected to the starting module 3, the emitter of the first transistor Q402 is connected to the first voltage dividing unit 62, the cathode of the first voltage stabilizing diode ZD402 is connected to the base of the first transistor Q402, the anode of the first voltage stabilizing diode ZD402 is grounded, the positive electrode of the first electrolytic capacitor C414 is connected to the collector of the first transistor Q402, the negative electrode of the first electrolytic capacitor C414 is grounded, one end of the first capacitor C408 is connected to the emitter of the first transistor Q402, the other end of the first capacitor C408 is grounded, one end of the first resistor R405 is connected to the base of the first transistor Q402, and the other end of the first resistor R405 is connected to the collector of the first transistor Q402. In the present invention, the linear voltage stabilization unit 61 is provided to linearly stabilize the output voltage.

[0044] The first voltage dividing unit 62 includes a second resistor R425A and a third resistor R426, one end of the second resistor R425A is connected to the emitter of the first transistor Q402, the other end of the second resistor R425A is connected to one end of the third resistor R426, the other end of the third resistor R426 is grounded, and the common end between the second resistor R425A and the third resistor R426 is connected to the self-locking unit 64. In the present invention, through the configuration of the first voltage dividing unit 62, the voltage output by the linear voltage stabilizing unit 61 can be divided before the self-locking unit 64 is turned on.

[0045] The second voltage-dividing unit 63 includes a fourth resistor R105A, a fifth resistor R105B, a sixth resistor R105C, and a seventh resistor R105D. One end of the fourth resistor R105A is connected to the output end of the rectifying and filtering module 2, the other end of the fourth resistor R105A is connected to one end of the fifth resistor R105B, the other end of the fifth resistor R105B is connected to one end of the sixth resistor R105C, the other end of the sixth resistor R105C is connected to one end of the seventh resistor R105D, the other end of the seventh resistor R105D is grounded, and the common end between the sixth resistor R105C and the seventh resistor R105D is connected to the self-locking unit 64. In the present invention, the high-frequency voltage output by the rectifying and filtering module 2 is divided by the second voltage-dividing unit 63 and then provided to the first MOS tube Q101A through the self-locking unit 64 to turn it on.

[0046] The self-locking unit 64 includes a second triode Q404, a third triode Q405, an eighth resistor R423, a ninth resistor R424, a tenth resistor R425, an eleventh resistor R427, and a second capacitor C413; the base of the second triode Q404 is connected to the common end between the second resistor R425A and the third resistor R426, the emitter of the second triode Q404 is connected to one end of the eleventh resistor R427, the other end of the eleventh resistor R427 is connected to the gate of the first MOS tube Q101A, the collector of the second triode Q404 is connected to one end of the ninth resistor R424, the other end of the ninth resistor R424 is connected to the third The base of the transistor Q405 is connected, the emitter of the third transistor Q405 is connected to the common end between the sixth resistor R105C and the seventh resistor R105D, the collector of the third transistor Q405 is connected to one end of the tenth resistor R425, the other end of the tenth resistor R425 is connected to the base of the second transistor Q404, one end of the eighth resistor R423 is connected to the emitter of the third transistor Q405, the other end of the eighth resistor R423 is connected to the base of the third transistor Q405, one end of the second capacitor C413 is connected to the common end between the tenth resistor R425 and the second transistor Q404, and the other end of the second capacitor C413 is grounded. In the present invention, the voltage divided by the first voltage divider unit 62 turns on the second transistor Q404, and after the second transistor Q404 is turned on, the third transistor Q405 is also turned on, thereby entering a deep conduction state, so that the first MOS transistor Q101A is turned on more stably.

[0047] Among them, the rectifier and filter module 2 includes a first rectifier bridge BD101, a second rectifier bridge BD102, and a second electrolytic capacitor C101, the input protection module 1 includes a neutral line input terminal L, a live line input terminal N, a fuse F101 and a varistor MOV101, the fuse F101 is connected in series to the neutral line input terminal L, one end of the varistor MOV101 is connected to the neutral line input terminal L, and the other end of the varistor MOV101 is connected to the live line input terminal N, the first rectifier bridge BD101 and the second rectifier bridge BD102 are both full bridges formed by a combination of four rectifier diodes, and the two AC input terminals of the first rectifier bridge BD101 are The first rectifier bridge BD101 is connected to the neutral line input terminal L, one of the DC output terminals of the first rectifier bridge BD101 is connected to the positive electrode of the second electrolytic capacitor C101, the other DC output terminal of the first rectifier bridge BD101 is connected to one end of the first thermistor R1 and is grounded, the other end of the first thermistor R1 is connected to the negative electrode of the second electrolytic capacitor C101, the two AC input terminals of the second rectifier bridge BD102 are both connected to the live line input terminal N, one of the DC output terminals of the second rectifier bridge BD102 is connected to the positive electrode of the second electrolytic capacitor C101, and the other DC output terminal of the second rectifier bridge BD102 is connected to one end of the first thermistor R1 that is grounded. In the present invention, the fuse F101 and the varistor MOV101 play a protective role, the first rectifier bridge BD101 and the second rectifier bridge BD102 play a rectifying role, converting alternating current into direct current, the second electrolytic capacitor C101 plays a filtering role, and the first thermistor R1 plays a current limiting role, which can suppress the instantaneous impact current when starting up, and the fourth resistor R105A of the self-locking circuit 6 is connected to the positive electrode of the second electrolytic capacitor C101.

[0048] The voltage divider module 5 includes a twelfth resistor R107, a thirteenth resistor R113, a fourteenth resistor R104 and a fifteenth resistor R103, one end of the twelfth resistor R107 is connected to the neutral line input terminal L, the other end of the twelfth resistor R107 is connected to one end of the thirteenth resistor R113, the other end of the thirteenth resistor R113 is connected to the live line input terminal N, one end of the fourteenth resistor R104 is connected to the common end between the twelfth resistor R107 and the thirteenth resistor R113, the other end of the fourteenth resistor R104 is connected to one end of the fifteenth resistor R103, and the other end of the fifteenth resistor R103 is connected to the start-up module 3. In the present invention, the voltage divider module 5 can divide the voltage input through the input protection module 1 and transmit it to the start-up module 3 as its start-up voltage.

[0049] Among them, the startup module 3 includes a first control chip U101, a second MOS tube Q101, a second thermistor NTC102, a first diode D102, a second diode D103, a third diode D104, a fourth diode D105, a third electrolytic capacitor C105, a third capacitor C107, a fourth capacitor 108, a fifth capacitor C110, a sixth capacitor C112, a sixteenth resistor R101, a seventeenth resistor R109, an eighteenth resistor R110, a nineteenth resistor R111, a twentieth resistor R112, a twenty-first resistor R115, a twenty-second resistor R116, a twenty-third resistor R120, and a twenty-fourth resistor R130. The model of the first control chip U101 is OB2273. The first control chip U101 includes a GND pin, an FB pin, a PRT pin, a GATE pin, a VDD pin, and a SENSE pin.

[0050] The GND pin of the first control chip U101 is grounded; the anode of the fourth diode D105 is connected to the PRT pin of the first control chip U101, the cathode of the fourth diode D105 is connected to one end of the second thermistor NTC102, the other end of the second thermistor NTC102 is connected to one end of the twenty-third resistor R120, and the other end of the twenty-third resistor R120 is grounded; the GATE pin of the first control chip U101 is connected to one end of the sixteenth resistor R101, the other end of the sixteenth resistor R101 is connected to one end of the twentieth resistor R112, the other end of the twentieth resistor R112 is connected to one end of the twenty-fourth resistor R130, the other end of the twenty-fourth resistor R130 is connected to one end of the seventeenth resistor R109, and the seventeenth resistor R109 is connected to one end of the twenty-third resistor R109. The other end of R109 is grounded, the cathode of the third diode D104 is connected to the common end between the sixteenth resistor R101 and the twentieth resistor R112, the anode of the third diode D104 is connected to the common end of the twentieth resistor R112 and the twenty-fourth resistor R130, the gate of the second MOS transistor Q101 is connected to the anode of the third diode D104, the source of the second MOS transistor Q101 is connected to the common end of the twenty-fourth resistor R130 and the seventeenth resistor R109, the end of the first primary side 411 of the transformer 41 connected to the start-up module 3 is connected to the drain of the second MOS transistor Q101, one end of the sixth capacitor C112 is connected to the source of the second MOS transistor Q101, and the other end of the sixth capacitor C112 is connected to the drain of the second MOS transistor Q101;

[0051] The VDD pin of the first control chip U101 is connected to one end of the twenty-first resistor R115, the other end of the twenty-first resistor R115 is connected to the cathode of the second diode D103, the anode of the second diode D103 is connected to the cathode of the first diode D102, the anode of the first diode D102 is connected to one end of the twenty-second resistor R116, the other end of the twenty-second resistor R116 is connected to one end of the second primary side 412 of the transformer 41 of the output module 4, the other end of the second primary side 412 of the transformer 41 is grounded, and the common end of the twenty-first resistor R115 and the second diode D103 is connected to the fifteenth resistor R103 of the voltage divider module 5. , two ends of the fifth capacitor C110 are connected in parallel to two ends of the first diode D102, one end of the fourth capacitor C108 is connected to the common end between the fifteenth resistor R103 and the VDD pin of the first control chip U101, the other end of the fourth capacitor C108 is connected to the negative electrode of the third electrolytic capacitor C105, the positive electrode of the third electrolytic capacitor C105 is connected to the common end between the first diode D102 and the second diode D103, and the common end between the fourth capacitor C108 and the third electrolytic capacitor C105 is grounded, and the collector of the first transistor Q402 of the self-locking circuit 6 is connected to the common end between the first diode D102 and the second diode D103;

[0052] A SENSE pin of the first control chip U101 is connected to one end of the third capacitor C107, the other end of the third capacitor C107 is grounded, one end of the nineteenth resistor R111 is connected to a common end between the SENSE pin of the first control chip U101 and the third capacitor C107, and the other end of the nineteenth resistor R111 is connected to a common end between the seventeenth resistor R109 and the twenty-fourth resistor R130;

[0053] One end of the eighteenth resistor R110 is connected to the PRT pin of the first control chip U101 and the common end of the first diode D102, and the other end of the eighteenth resistor R110 is connected to the positive electrode of the third electrolytic capacitor C105. In the present invention, the voltage divided by the voltage divider module 5 is provided to the first control chip U101 as a startup voltage. When the first control chip U101 is started, its GATE pin outputs a high level to turn on the second MOS tube Q101, so that the power circuit can work and output normally.

[0054] Among them, the power output end includes a positive output end 42 and a negative output end 43, the output module 4 also includes a second control chip U202, a third MOS tube Q201, a fourth electrolytic capacitor C201, a seventh capacitor C202, an eighth capacitor C203, a twenty-fifth resistor R201, a twenty-sixth resistor R202, a twenty-seventh resistor R207, a twenty-eighth resistor R210, and a twenty-ninth resistor R211, and the second control chip includes a VG pin, a VSS pin, a HVC pin, a VD pin, a SLEW pin, and a VDD pin;

[0055] The VG pin of the second control chip U202 is connected to the gate of the third MOS tube Q201, the source of the third MOS tube Q201 is connected to one end of the secondary side 413 of the transformer 41, the other end of the secondary side 413 of the transformer 41 is connected to the feedback module 7, the feedback module 7 is connected to the FB pin of the first control chip U101, the source of the third MOS tube Q201 is connected to one end of the twenty-eighth resistor R210, the other end of the twenty-eighth resistor R210 is connected to the VD pin of the second control chip U202, the VSS pin of the second control chip U202 is connected to the source of the third MOS tube Q201, the HVC pin of the second control chip U202 is connected to the VSS pin of the second control chip U202, the SLEW of the second control chip U202 is connected to one end of the twenty-ninth resistor R211, the other end of the twenty-ninth resistor R211 is connected to one end of the eighth capacitor C203, and the other end of the eighth capacitor C203 The twenty-sixth resistor R202 is connected to the VDD pin of the second control chip U202, the common end of the twenty-ninth resistor R211 and the eighth capacitor C203 is connected to the source of the third MOS tube Q201, one end of the twenty-sixth resistor R202 is connected to the source of the third MOS tube Q201, the other end of the twenty-sixth resistor R202 is connected to one end of the seventh capacitor C202, the other end of the seventh capacitor C202 is connected to the positive electrode of the fourth electrolytic capacitor C201, the positive electrode of the fourth electrolytic capacitor C201 is connected to the positive electrode output terminal 42, the negative electrode of the fourth electrolytic capacitor C201 is connected to the negative electrode output terminal 43, the two ends of the twenty-fifth resistor R201 are connected in parallel to the two ends of the fourth electrolytic capacitor C201, one end of the twenty-seventh resistor R207 is connected to the common end between the twenty-sixth resistor R202 and the source of the third MOS tube Q201, and the other end of the twenty-seventh resistor R207 is connected to the common end between the twenty-sixth resistor R202 and the seventh capacitor C202. In the present invention, the normal output of the power supply circuit is achieved by setting the output module 4.

[0056] The feedback module 7 includes a first photocoupler, a second voltage stabilizing diode U201, a ninth capacitor C106, a tenth capacitor C109, an eleventh capacitor C204, a twelfth capacitor C205, a thirtieth resistor RJ102, a thirty-first resistor R203, a thirty-second resistor R204, a thirty-third resistor R205, a thirty-fourth resistor R206, a thirty-fifth resistor R208, and a thirty-sixth resistor R208A. The first photocoupler includes a light emitting diode U102A and a phototransistor U102B.

[0057] The emitter of the phototransistor U102B is grounded, the collector of the phototransistor U102B is connected to one end of the 30th resistor RJ102, the other end of the 30th resistor RJ102 is connected to one end of the ninth capacitor C106, the other end of the ninth capacitor C106 is connected to one end of the tenth capacitor C109, the other end of the tenth capacitor C109 is connected to the emitter of the phototransistor U102B, and the common end between the 30th resistor RJ102 and the ninth capacitor C106 is connected to the FB pin of the first control chip U101;

[0058] The cathode of the light-emitting diode U102A is connected to the cathode of the second voltage-stabilizing diode U201, the anode of the second voltage-stabilizing diode U201 is connected to one end of the thirty-fifth resistor R208, the other end of the thirty-fifth resistor R208 is connected to the cathode of the second voltage-stabilizing diode U201, the end of the secondary side 413 of the transformer 41 connected to the feedback module 7 is connected to the common end between the anode of the second voltage-stabilizing diode U201 and the thirty-fifth resistor R208, one end of the thirty-first resistor R203 is connected to the anode of the light-emitting diode U102A, the other end of the thirty-first resistor R203 is connected to one end of the thirty-fourth resistor R206, the other end of the thirty-fourth resistor R206 is connected to one end of the thirty-sixth resistor R208A, and the other end of the thirty-sixth resistor R208A is connected to the second voltage-stabilizing diode U2 01 is connected to the common end between the anode of the 35th resistor R208, the two ends of the 32nd resistor R204 are connected in parallel to the two ends of the light emitting diode U102A, one end of the 33rd resistor R205 is connected to the common end between the cathode of the second voltage stabilizing diode U201 and the cathode of the light emitting diode U102A, the other end of the 33rd resistor is connected to one end of the 11th capacitor C204, the other end of the 11th capacitor C204 is connected to one end of the 12th capacitor C205, the other end of the 12th capacitor C205 is connected to the common end between the 36th resistor R208A and the 34th resistor R206, the common end between the 31st resistor R203 and the 34th resistor R206 is connected to the common end between the positive electrode of the 7th capacitor C202 and the 4th electrolytic capacitor C201 of the output module 4. In the present invention, the function of the feedback module 7 is to sample the output voltage to achieve a circuit with stable performance.

[0059] like Figure 3 As shown, the working process of the power supply circuit for suppressing the instantaneous inrush current at startup implemented by the present invention is as follows:

[0060] When the input protection module 1 inputs AC power, the voltage is rectified by the first rectifier bridge BD101 and the second rectifier bridge BD102 to charge the second electrolytic capacitor C101. At this time, because the second electrolytic capacitor C101 is connected in series with the first thermistor R1, the inrush current at startup varies due to the different resistance values ​​of the first thermistor R1. For example, when the designed startup instantaneous current is 60A, the resistance value of the first thermistor R1 = 264*1.14 / 60 = 5 ohms (264V is the highest AC input voltage, 1.14 is the rectification coefficient, that is, 264*1.14 is the voltage on the capacitor) At the same time, the AC voltage is divided by the twelfth resistor R107 and the thirteenth resistor R113, and then provided to the first control chip U101 as a startup voltage after passing through the fourteenth resistor R104, the fifteenth resistor R103 and the twenty-first resistor R115. When the first control chip U101 is started, its GATE pin outputs a high level to turn on the second MOS tube Q101, so that the product can work normally and output. At this time, the VCC auxiliary winding of the transformer 41, that is, the second primary side 412, is powered normally, so the VCC voltage is linearly stabilized and output by the linear voltage regulator unit 61 to a voltage of about 5V. Specifically, the voltage at VCC marked in the figure is filtered by the first electrolytic capacitor C414, and then limited to the first transistor Q402 and the first voltage regulator diode ZD402 through the first resistor R405. Since the first voltage regulator diode ZD402 is selected as 6V, the base voltage of all the first transistors Q402 is clamped to 6V. At the same time, since the first transistor Q402 has a bias VBE=0.6V, the voltage output by the linear regulator is 6-0.6V=5.4V.

[0061] The 5.4V voltage outputted by the linear voltage regulator is divided into 2.5V by the second resistor R425A and the third resistor R426. Since 2.5V is greater than 0.6V, the second triode Q404 is turned on. When the second triode Q404 is turned on, the high-frequency voltage outputted by the rectifier and filter module 2 is divided by the second voltage divider unit 63 and the voltage is passed through the eleventh resistor R427 to the base of the first MOS tube Q101A, thereby turning on the first MOS tube Q101A. At the same time, because the second triode Q404 is turned on, the base voltage of the third triode Q405 is lower than the voltage of its emitter, thereby turning on the third triode Q405. When the third triode Q405 is turned on, the voltage of the emitter flows into the base of the second diode D103, thereby turning it on deeply.

[0062] The advantages of the present invention are:

[0063] Compared with the prior art, in the present invention, the instantaneous inrush current at startup can be suppressed by setting the first thermistor. At the same time, after the first thermistor is short-circuited by setting the self-locking circuit, the power supply circuit can achieve unlimited current resistance during normal operation, avoiding the loss caused by the existence of the first thermistor, thereby improving the power supply efficiency and meeting the current energy efficiency requirements; and there will be no problem of higher inrush current at startup due to the smaller resistance of the first thermistor, thereby avoiding damage to the product or power supply equipment.

[0064] The above lists the preferred embodiments of the present invention, which are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power supply circuit for suppressing instantaneous inrush current when starting up, characterized in that It includes an input protection module, a rectification and filtering module, a startup module and an output module; the input protection module is connected to the rectification and filtering module and the startup module respectively, and the output module is provided with a first input end and a second input end, and the first input end and the second input end are connected to the rectification and filtering module and the startup module respectively; The input protection module is used to input an AC voltage. After the AC voltage passes through the rectification and filtering module, a stable DC voltage is formed and input to the first input terminal of the output module. A voltage dividing module is also provided between the input protection module and the startup module. The AC voltage input through the input protection module is divided by the voltage dividing module to form a startup voltage of the startup module. After the startup module is started, the second input terminal of the output module is turned on, so that the output module works normally and the current output is realized. The rectifier and filter module is connected in series with a first thermistor, and a self-locking circuit is connected in parallel at both ends of the first thermistor, and the self-locking circuit is connected to the start module. When the output module outputs normally, the start module controls the self-locking circuit to be turned on, thereby short-circuiting the first thermistor; The output module is also provided with a transformer and a power output end for outputting current, the transformer includes a first primary side, a second primary side and a secondary side, the secondary side is connected to the power output end, one end of the first primary side of the transformer is connected to the rectification and filtering module, the other end of the first primary side of the transformer is connected to the starting module, one end of the second primary side of the transformer is connected to the starting module, and the other end of the second primary side of the transformer is grounded; the AC voltage input by the input protection module forms a stable DC voltage input to one end of the first primary side of the transformer after passing through the rectification and filtering module, the AC voltage input through the input protection module is divided by the voltage dividing module to form the starting voltage of the starting module, and after the starting module is started, the other end of the first primary side of the transformer is turned on, so that the output module works normally and the current is output through the power output end; the end of the first primary side of the transformer connected to the rectification and filtering module is the first input end of the output module, and the end of the first primary side of the transformer connected to the starting module is the second input end of the output module; The self-locking circuit includes a linear voltage stabilizing unit, a first voltage dividing unit, a second voltage dividing unit, a self-locking unit and a first MOS tube, one end of the linear voltage stabilizing unit is connected to the startup module, the other end of the linear voltage stabilizing unit is connected to the self-locking unit through the first voltage dividing unit, the self-locking unit is connected to the output end of the rectifier and filter module through the second voltage dividing unit, the gate of the first MOS tube is connected to the self-locking unit, the source and drain of the first MOS tube are respectively connected to the two ends of the first thermistor, and the source of the first MOS tube is grounded; when the startup module is started, the linear voltage stabilizing unit is turned on, the voltage output by the linear voltage stabilizing unit passes through the first voltage dividing unit to turn on the self-locking unit, and after the self-locking unit is turned on, the voltage output by the rectifier and filter module is divided by the second voltage dividing unit and then supplied to the gate of the first MOS tube through the self-locking unit, thereby turning on the first MOS tube, causing the first thermistor to short-circuit; The linear voltage stabilizing unit includes a first transistor, a first voltage stabilizing diode, a first electrolytic capacitor, a first capacitor, and a first resistor; the collector of the first transistor is connected to the startup module, the emitter of the first transistor is connected to the first voltage dividing unit, the cathode of the first voltage stabilizing diode is connected to the base of the first transistor, the anode of the first voltage stabilizing diode is grounded, the positive electrode of the first electrolytic capacitor is connected to the collector of the first transistor, the negative electrode of the first electrolytic capacitor is grounded, one end of the first capacitor is connected to the emitter of the first transistor, the other end of the first capacitor is grounded, one end of the first resistor is connected to the base of the first transistor, and the other end of the first resistor is connected to the collector of the first transistor; The first voltage dividing unit includes a second resistor and a third resistor, one end of the second resistor is connected to the emitter of the first transistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is grounded, and a common end between the second resistor and the third resistor is connected to the self-locking unit; The second voltage dividing unit includes a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor, one end of the fourth resistor is connected to the output end of the rectification and filtering module, the other end of the fourth resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to one end of the seventh resistor, the other end of the seventh resistor is grounded, and the common end between the sixth resistor and the seventh resistor is connected to the self-locking unit; The self-locking unit includes a second triode, a third triode, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, and a second capacitor; the base of the second triode is connected to the common end between the second resistor and the third resistor, the emitter of the second triode is connected to one end of the eleventh resistor, the other end of the eleventh resistor is connected to the gate of the first MOS tube, the collector of the second triode is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to the base of the third triode, the emitter of the third triode is connected to the common end between the sixth resistor and the seventh resistor, the collector of the third triode is connected to one end of the tenth resistor, the other end of the tenth resistor is connected to the base of the second triode, one end of the eighth resistor is connected to the emitter of the third triode, the other end of the eighth resistor is connected to the base of the third triode, one end of the second capacitor is connected to the common end between the tenth resistor and the second triode, and the other end of the second capacitor is grounded.

2. The power supply circuit for suppressing instantaneous inrush current at startup according to claim 1, characterized in that The rectifier and filter module includes a first rectifier bridge, a second rectifier bridge, and a second electrolytic capacitor. The input protection module includes a neutral line input terminal, a live line input terminal, a fuse and a varistor. The fuse is connected in series to the neutral line input terminal. One end of the varistor is connected to the neutral line input terminal, and the other end of the varistor is connected to the live line input terminal. The first rectifier bridge and the second rectifier bridge are full bridges formed by a combination of four rectifier diodes. The two AC input terminals of the first rectifier bridge are connected to the neutral line input terminal. One of the DC output terminals of the first rectifier bridge is connected to the positive electrode of the second electrolytic capacitor. The other DC output terminal of the first rectifier bridge is connected to one end of the first thermistor and is grounded. The other end of the first thermistor is connected to the negative electrode of the second electrolytic capacitor. The two AC input terminals of the second rectifier bridge are connected to the live line input terminal. One of the DC output terminals of the second rectifier bridge is connected to the positive electrode of the second electrolytic capacitor. The other DC output terminal of the second rectifier bridge is connected to one end of the first thermistor that is grounded. The fourth resistor of the self-locking circuit is connected to the positive electrode of the second electrolytic capacitor.

3. The power supply circuit for suppressing instantaneous inrush current at startup according to claim 2, characterized in that The voltage divider module includes a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a fifteenth resistor, one end of the twelfth resistor is connected to the neutral line input end, the other end of the twelfth resistor is connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is connected to the live line input end, one end of the fourteenth resistor is connected to the common end between the twelfth resistor and the thirteenth resistor, the other end of the fourteenth resistor is connected to one end of the fifteenth resistor, and the other end of the fifteenth resistor is connected to the starting module.

4. The power supply circuit for suppressing instantaneous inrush current at startup according to claim 3, characterized in that The startup module includes a first control chip, a second MOS tube, a second thermistor, a first diode, a second diode, a third diode, a fourth diode, a third electrolytic capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a twenty-third resistor, and a twenty-fourth resistor. The model of the first control chip is OB2273, and the first control chip includes a GND pin, an FB pin, a PRT pin, a GATE pin, a VDD pin, and a SENSE pin. The GND pin of the first control chip is grounded; the anode of the fourth diode is connected to the PRT pin of the first control chip, the cathode of the fourth diode is connected to one end of the second thermistor, the other end of the second thermistor is connected to one end of the twenty-third resistor, and the other end of the twenty-third resistor is grounded; the GATE pin of the first control chip is connected to one end of the sixteenth resistor, the other end of the sixteenth resistor is connected to one end of the twentieth resistor, the other end of the twentieth resistor is connected to one end of the twenty-fourth resistor, the other end of the twenty-fourth resistor is connected to one end of the seventeenth resistor, and the other end of the seventeenth resistor is grounded; the cathode of the third diode is connected to the common end between the sixteenth resistor and the twentieth resistor, the anode of the third diode is connected to the common end of the twentieth resistor and the twenty-fourth resistor, the gate of the second MOS tube is connected to the anode of the third diode, the source of the second MOS tube is connected to the common end of the twenty-fourth resistor and the seventeenth resistor, the end of the first primary side of the transformer connected to the startup module is connected to the drain of the second MOS tube, one end of the sixth capacitor is connected to the source of the second MOS tube, and the other end of the sixth capacitor is connected to the drain of the second MOS tube; The VDD pin of the first control chip is connected to one end of the twenty-first resistor, the other end of the twenty-first resistor is connected to the cathode of the second diode, the anode of the second diode is connected to the cathode of the first diode, the anode of the first diode is connected to one end of the twenty-second resistor, the other end of the twenty-second resistor is connected to one end of the second primary side of the transformer of the output module, the other end of the second primary side of the transformer is grounded, the common end of the twenty-first resistor and the second diode is connected to the fifteenth resistor of the voltage divider module, the two ends of the fifth capacitor are connected in parallel to the two ends of the first diode, one end of the fourth capacitor is connected to the common end between the fifteenth resistor and the VDD pin of the first control chip, the other end of the fourth capacitor is connected to the negative electrode of the third electrolytic capacitor, the positive electrode of the third electrolytic capacitor is connected to the common end between the first diode and the second diode, and the common end between the fourth capacitor and the third electrolytic capacitor is grounded, and the collector of the first transistor of the self-locking circuit is connected to the common end between the first diode and the second diode; The SENSE pin of the first control chip is connected to one end of the third capacitor, the other end of the third capacitor is grounded, one end of the nineteenth resistor is connected to the common end between the SENSE of the first control chip and the third capacitor, and the other end of the nineteenth resistor is connected to the common end between the seventeenth resistor and the twenty-fourth resistor; one end of the eighteenth resistor is connected to the PRT pin of the first control chip and the common end of the first diode, and the other end of the eighteenth resistor is connected to the positive electrode of the third electrolytic capacitor.

5. The power supply circuit for suppressing instantaneous inrush current during startup according to claim 4, characterized in that The power output end includes a positive output end and a negative output end, the output module also includes a second control chip, a third MOS tube, a fourth electrolytic capacitor, a seventh capacitor, an eighth capacitor, a twenty-fifth resistor, a twenty-sixth resistor, a twenty-seventh resistor, a twenty-eighth resistor, and a twenty-ninth resistor, and the second control chip includes a VG pin, a VSS pin, a HVC pin, a VD pin, a SLEW pin, and a VDD pin; The VG pin of the second control chip is connected to the gate of the third MOS tube, the source of the third MOS tube is connected to one end of the secondary side of the transformer, the other end of the secondary side of the transformer is connected to a feedback module, the feedback module is connected to the FB pin of the first control chip, the source of the third MOS tube is connected to one end of the twenty-eighth resistor, the other end of the twenty-eighth resistor is connected to the VD pin of the second control chip, the VSS pin of the second control chip is connected to the source of the third MOS tube, the HVC pin of the second control chip is connected to the VSS pin of the second control chip, the SLEW of the second control chip is connected to one end of the twenty-ninth resistor, the other end of the twenty-ninth resistor is connected to one end of the eighth capacitor, and the eighth capacitor The other end of the twenty-fifth resistor is connected to the VDD pin of the second control chip, the common end of the twenty-ninth resistor and the eighth capacitor is connected to the source of the third MOS tube, one end of the twenty-sixth resistor is connected to the source of the third MOS tube, the other end of the twenty-sixth resistor is connected to one end of the seventh capacitor, the other end of the seventh capacitor is connected to the positive electrode of the fourth electrolytic capacitor, the positive electrode of the fourth electrolytic capacitor is connected to the positive output end, the negative electrode of the fourth electrolytic capacitor is connected to the negative output end, the two ends of the twenty-fifth resistor are connected in parallel to the two ends of the fourth electrolytic capacitor, one end of the twenty-seventh resistor is connected to the common end between the twenty-sixth resistor and the source of the third MOS tube, and the other end of the twenty-seventh resistor is connected to the common end between the twenty-sixth resistor and the seventh capacitor.

6. The power supply circuit for suppressing instantaneous inrush current during startup according to claim 5, characterized in that The feedback module includes a first photocoupler, a second voltage-stabilizing diode, a ninth capacitor, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, a thirtieth resistor, a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, and a thirty-sixth resistor, and the first photocoupler includes a light-emitting diode and a phototransistor; The emitter of the phototransistor is grounded, the collector of the phototransistor is connected to one end of the 30th resistor, the other end of the 30th resistor is connected to one end of the ninth capacitor, the other end of the ninth capacitor is connected to one end of the tenth capacitor, the other end of the tenth capacitor is connected to the emitter of the phototransistor, and the common end between the 30th resistor and the ninth capacitor is connected to the FB pin of the first control chip; The cathode of the light-emitting diode is connected to the cathode of the second voltage-stabilizing diode, the anode of the second voltage-stabilizing diode is connected to one end of the thirty-fifth resistor, the other end of the thirty-fifth resistor is connected to the cathode of the second voltage-stabilizing diode, the end of the secondary side of the transformer connected to the feedback module is connected to the common end between the anode of the second voltage-stabilizing diode and the thirty-fifth resistor, one end of the thirty-first resistor is connected to the anode of the light-emitting diode, the other end of the thirty-first resistor is connected to one end of the thirty-fourth resistor, the other end of the thirty-fourth resistor is connected to one end of the thirty-sixth resistor, and the other end of the thirty-sixth resistor is connected to the second voltage-stabilizing diode. The anode of the tube is connected to the common end between the thirty-fifth resistor, the two ends of the thirty-second resistor are connected in parallel to the two ends of the light-emitting diode, one end of the thirty-third resistor is connected to the common end between the cathode of the second voltage-stabilizing diode and the cathode of the light-emitting diode, the other end of the thirty-third resistor is connected to one end of the eleventh capacitor, the other end of the eleventh capacitor is connected to one end of the twelfth capacitor, the other end of the twelfth capacitor is connected to the common end between the thirty-sixth resistor and the thirty-fourth resistor, the common end between the thirty-first resistor and the thirty-fourth resistor is connected to the common end between the seventh capacitor of the output module and the positive electrode of the fourth electrolytic capacitor.

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