Overcurrent protection topology and overcurrent protection system

Abstract

The embodiment of the utility model discloses an overcurrent protection topology and an overcurrent protection system. The over-current protection topology comprises a level conversion circuit, an over-current protection circuit and an output circuit. The level conversion circuit is connected with the output circuit, and the level conversion circuit is used for receiving externally input PWM waves and outputting level signals complementary with the PWM waves to the output circuit; the over-current protection circuit is connected with the level conversion circuit and the output circuit, the over-current protection circuit is used for controlling the output of the level conversion circuit, and the output circuit is used for outputting a preset voltage. According to the utility model, hardware over-current protection of the drive circuit can be realized, so that an auxiliary power supply part is changed into step-by-step starting, the circuit structure is optimized, the function is realized by using fewer devices, and the cost is reduced.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of power supply, and in particular to an overcurrent protection topology and an overcurrent protection system. Background Art

[0002] Figure 1 This is a driving principle diagram of an existing driving circuit, refer to Figure 1 , the drive circuit works by using the secondary side signal HF-POWER of the auxiliary power supply transformer. The drive voltage of the power tube in the inverter is composed of a simple forward circuit. The primary input of the drive transformer of the forward circuit uses the HF-POWER signal pulled out from the secondary side of the auxiliary power supply transformer. Although this drive circuit is simple, it lacks overcurrent protection. When the auxiliary power supply is started, it will bring a large starting current, and the transformer of the auxiliary power supply needs a large primary inductance. Utility Model Content

[0003] The utility model provides an overcurrent protection topology and an overcurrent protection system, which can realize hardware overcurrent protection of a driving circuit, so that an auxiliary power supply part is started step by step, the circuit structure is optimized, and fewer devices are used to realize the function, thereby reducing costs.

[0004] According to one aspect of the utility model, an overcurrent protection topology is provided, the overcurrent protection topology comprising: a level conversion circuit, an overcurrent protection circuit and an output circuit;

[0005] The level conversion circuit is connected to the output circuit, and the level conversion circuit is used to receive an externally input PWM wave and output a level signal complementary to the PWM wave to the output circuit;

[0006] The overcurrent protection circuit is connected to the level conversion circuit and the output circuit. The overcurrent protection circuit is used to control the output of the level conversion circuit. The output circuit is used to output a preset voltage.

[0007] Optionally, the level conversion circuit includes: a first protection unit, a first switch unit, a voltage dividing unit, a second protection unit and a second switch unit;

[0008] The first protection unit is connected between the control end and the second end of the first switch unit, the first end of the first switch unit is connected to the first end of the voltage divider unit, the first end of the second protection unit and the first end of the second switch unit, the second end of the voltage divider unit is connected to the second end of the second switch unit and then to the power supply end, and the third end of the second switch unit is connected to the second end of the second protection unit and the output circuit.

[0009] Optionally, the first protection unit includes a thirteenth diode, the first switch unit includes a tenth transistor, the voltage divider unit includes a ninth resistor, the second protection unit includes a tenth diode, and the second switch unit includes a ninth transistor;

[0010] The thirteenth diode is connected between the control end and the second end of the tenth transistor, the first end of the tenth transistor is connected to the first end of the ninth resistor, the first end of the tenth diode and the first end of the ninth transistor, the second end of the ninth resistor is connected to the second end of the ninth transistor and then to the power supply end, and the third end of the ninth transistor is connected to the second end of the tenth diode and the output circuit.

[0011] Optionally, the overcurrent protection circuit includes: a first filtering unit, a third switching unit, a fourth switching unit and a second filtering unit;

[0012] The first end of the first filter unit is connected to the level conversion circuit and the first end of the fourth switch unit, the second end of the first filter unit is connected to the first end of the third switch unit and the second end of the fourth switch unit, and the second filter unit is connected to the second end, the third end of the third switch unit, the third end of the fourth switch unit and the output circuit.

[0013] Optionally, the first filtering unit includes an eleventh resistor and a sixteenth capacitor, the third switch unit includes a sixth transistor, the fourth switch unit includes a seventh transistor, and the second filtering unit includes a fifteenth capacitor and an eighth resistor;

[0014] The first ends of the eleventh resistor and the sixteenth capacitor are connected to the level conversion circuit and the first end of the seventh transistor, the second ends of the eleventh resistor and the sixteenth capacitor are connected to the first end of the sixth transistor and the second end of the seventh transistor, the first end of the fifteenth capacitor is connected to the second end of the sixth transistor, the third end of the seventh transistor and the first end of the eighth resistor, the second end of the eighth resistor is connected to the output circuit, and the second end of the fifteenth capacitor is connected to the third end of the sixth transistor and then grounded.

[0015] Optionally, the output circuit includes: a transformer, a driving unit, a switch unit, an overcurrent unit, a first voltage limiting unit and a second voltage limiting unit;

[0016] The first end of the driving unit is connected to the level conversion circuit, the second end of the driving unit is connected to the control end of the switch unit, the first end of the switch unit is connected to the fifth end of the primary side of the transformer and the first end of the first voltage limiting unit, the second end of the first voltage limiting unit is connected to the first end of the second voltage limiting unit, the second end of the second voltage limiting unit is connected to the third end of the switch unit and the first end of the overcurrent unit, and the second end of the overcurrent unit is grounded.

[0017] Optionally, the driving unit includes a tenth resistor, the switching unit includes an eighth transistor, the overcurrent unit includes a fifth resistor, the first voltage limiting unit includes an eleventh diode, and the second voltage limiting unit includes a twelfth diode;

[0018] The first end of the tenth resistor is connected to the level conversion circuit, the second end of the tenth resistor is connected to the control end of the eighth transistor, the first end of the eighth transistor is connected to the fifth end of the primary side of the transformer and the first end of the eleventh diode, the second end of the eleventh diode is connected to the first end of the twelfth diode, the second end of the twelfth diode is connected to the third end of the eighth transistor and the first end of the fifth resistor, and the second end of the fifth resistor is grounded.

[0019] Optionally, the output circuit further includes: an eighth capacitor, a third diode, a first diode, a fifth capacitor, a sixth capacitor, a first resistor, a second diode, a fourth capacitor, a seventh capacitor, a fifth diode, a ninth capacitor, a tenth capacitor, a fourth diode, a third resistor, an eleventh capacitor and a twelfth capacitor;

[0020] The eighth capacitor is connected between the first end and the third end of the primary side of the transformer, and the third diode is connected between the first end and the second end of the primary side of the transformer;

[0021] The tenth end of the secondary side of the transformer is connected to the first end of the first diode, the second end of the first diode is connected to the first end of the fifth capacitor, the first end of the sixth capacitor, the first end of the first resistor, and the first end of the fourth capacitor, the second end of the first resistor is connected to the first end of the second diode, the second end of the fourth capacitor is connected to the first end of the seventh capacitor, the second end of the first resistor is connected to the second end of the fourth capacitor, and the second end of the seventh capacitor is connected to the second end of the second diode, the second end of the sixth capacitor, the second end of the fifth capacitor, and the ninth end of the secondary side of the transformer;

[0022] The seventh end of the secondary side of the transformer is connected to the first end of the ninth capacitor, the first end of the tenth capacitor, the first end of the fourth diode and the first end of the eleventh capacitor, the second end of the fourth diode is connected to the first end of the third resistor, the second end of the eleventh capacitor is connected to the first end of the twelfth capacitor, the second end of the fourth diode is connected to the second end of the eleventh capacitor, the second end of the twelfth capacitor is connected to the second end of the third resistor, the second end of the tenth capacitor, the second end of the ninth capacitor and the first end of the fifth diode, and the second end of the fifth diode is connected to the sixth end of the secondary side of the transformer.

[0023] Optionally, the overcurrent protection topology further includes: a first capacitor, a second capacitor and a third capacitor;

[0024] The first end of the first capacitor is connected to the first end of the second capacitor and the first end of the third capacitor and then connected to the power supply end, and the second end of the first capacitor is connected to the second end of the second capacitor and the second end of the third capacitor and then grounded.

[0025] According to another aspect of the present invention, an overcurrent protection system is provided. The overcurrent protection system includes any one of the overcurrent protection topologies described in the above aspect.

[0026] According to the technical solution of the embodiment of the utility model, when the overcurrent protection circuit is started, it will receive a current exceeding the threshold value, directly trigger the protection, control the output of the level conversion circuit, and suspend the output; and after the current becomes smaller, the overcurrent protection is gradually restored, so that the level conversion circuit can output normally, and the entire circuit obtains a preset output voltage. As a result, when the auxiliary power supply is started, it will not bring a large starting current, and the transformer of the auxiliary power supply does not need a large primary inductance, and the hardware overcurrent protection of the drive circuit can be realized, so that the auxiliary power supply part becomes a step-by-step start, the circuit structure is optimized, and fewer devices are used to realize this function, reducing costs. In summary, the utility model solves the problem that the existing drive circuit lacks overcurrent protection, brings a large starting current when the auxiliary power supply is started, and the transformer of the auxiliary power supply needs a large primary inductance.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present utility model, nor are they intended to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a driving principle diagram of an existing driving circuit;

[0030] Figure 2 It is a structural schematic diagram of an overcurrent protection topology provided according to an embodiment of the utility model;

[0031] Figure 3 It is a working diagram of an overcurrent protection topology provided according to an embodiment of the utility model;

[0032] Figure 4 It is a circuit schematic diagram of an overcurrent protection topology provided according to an embodiment of the utility model. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] Figure 2 is a schematic diagram of an overcurrent protection topology provided according to an embodiment of the present invention, with reference to Figure 2The embodiment of the utility model provides an overcurrent protection topology, which includes: a level conversion circuit 10, an overcurrent protection circuit 20 and an output circuit 30; the level conversion circuit 10 is connected to the output circuit 30, and the level conversion circuit 10 is used to receive an external input PWM wave and output a level signal complementary to the PWM wave to the output circuit 30; the overcurrent protection circuit 20 is connected to the level conversion circuit 10 and the output circuit 30, and the overcurrent protection circuit 20 is used to control the output of the level conversion circuit 10, and the output circuit 30 is used to output a preset voltage.

[0036] Specifically, the externally input PWM wave passes through the level conversion circuit 10, and outputs a level signal complementary to the PWM wave to the transistor in the output circuit 30, so that it works normally. When the overcurrent protection circuit 20 is started, it will receive a current exceeding the threshold, directly trigger the protection, control the output of the level conversion circuit 10, and suspend the output. And after the current becomes smaller, the overcurrent protection is gradually restored, so that the level conversion circuit 10 can output normally, and the entire circuit obtains a preset output voltage.

[0037] The level conversion circuit 10 uses level conversion to make the output PWM wave complementary to the input PWM waveform. The output circuit 30 controls the opening and closing of its internal transistor by the PWM wave output by the level conversion circuit 10, and feeds back the overcurrent signal to the overcurrent protection circuit 20 through voltage. The protection is triggered at startup, causing the transistor to turn off. And as the current decreases, the overcurrent protection will automatically recover, allowing the transistor to operate normally, thereby outputting a preset voltage.

[0038] Figure 3 This is a flowchart of an overcurrent protection topology provided according to an embodiment of the present utility model, referring to Figure 3 , by inputting PWM wave into the level conversion circuit to give the transistor action signal in the output circuit. If there is an overcurrent phenomenon, the overcurrent protection circuit will pull down the output of the level conversion circuit, causing the transistor in the output circuit to turn off.

[0039] According to the technical solution of the embodiment of the utility model, when the overcurrent protection circuit is started, it will receive a current exceeding the threshold value, directly trigger the protection, control the output of the level conversion circuit, and suspend the output; and after the current becomes smaller, the overcurrent protection is gradually restored, so that the level conversion circuit can output normally, and the entire circuit obtains a preset output voltage. As a result, when the auxiliary power supply is started, it will not bring a large starting current, and the transformer of the auxiliary power supply does not need a large primary inductance, and the hardware overcurrent protection of the drive circuit can be realized, so that the auxiliary power supply part becomes a step-by-step start, the circuit structure is optimized, and fewer devices are used to realize this function, reducing costs. In summary, the utility model solves the problem that the existing drive circuit lacks overcurrent protection, brings a large starting current when the auxiliary power supply is started, and the transformer of the auxiliary power supply needs a large primary inductance.

[0040] Figure 4 is a circuit schematic diagram of an overcurrent protection topology provided according to an embodiment of the utility model, referring to Figure 4 Optionally, the level conversion circuit 10 includes: a first protection unit 11, a first switch unit 12, a voltage divider unit 13, a second protection unit 14 and a second switch unit 15; the first protection unit 11 is connected between the control terminal G and the second terminal of the first switch unit 12, the first terminal of the first switch unit 12 is connected to the first terminal of the voltage divider unit 13, the first terminal of the second protection unit 14 and the first terminal of the second switch unit 15, the second terminal of the voltage divider unit 13 is connected to the second terminal of the second switch unit 15 and then connected to the power supply terminal VCC-12V, and the third terminal of the second switch unit 15 is connected to the second terminal of the second protection unit 14 and the output circuit 30.

[0041] Continue to refer Figure 4 Optionally, the first protection unit 11 includes a thirteenth diode D13, the first switch unit 12 includes a tenth transistor Q10, the voltage divider unit 13 includes a ninth resistor R9, the second protection unit 14 includes a tenth diode D10, and the second switch unit 15 includes a ninth transistor Q9; the thirteenth diode D13 is connected between the control terminal G and the second terminal of the tenth transistor Q10, the first end of the tenth transistor Q10 is connected to the first end of the ninth resistor R9, the first end of the tenth diode D10 and the first end of the ninth transistor Q9, the second end of the ninth resistor R9 is connected to the second end of the ninth transistor Q9 and then connected to the power supply terminal VCC-12V, and the third end of the ninth transistor Q9 is connected to the second end of the tenth diode D10 and the output circuit 30.

[0042] Continue to refer Figure 4Optionally, the overcurrent protection circuit 20 includes: a first filtering unit 21, a third switch unit 22, a fourth switch unit 23 and a second filtering unit 24; the first end of the first filtering unit 21 is connected to the level conversion circuit 10 and the first end of the fourth switch unit 23, the second end of the first filtering unit 21 is connected to the first end of the third switch unit 22 and the second end of the fourth switch unit 23, and the second filtering unit 24 is connected to the second end, the third end, the third end of the fourth switch unit 24 and the output circuit 30 of the third switch unit 22.

[0043] Continue to refer Figure 4 Optionally, the first filtering unit 21 includes an eleventh resistor R11 and a sixteenth capacitor C16, the third switch unit 22 includes a sixth transistor Q6, the fourth switch unit 23 includes a seventh transistor Q7, and the second filtering unit 24 includes a fifteenth capacitor C15 and an eighth resistor R8; the first ends of the eleventh resistor R11 and the sixteenth capacitor C16 are connected to the level conversion circuit 10 and the first end of the seventh transistor Q7, the second ends of the eleventh resistor R11 and the sixteenth capacitor C16 are connected to the first end of the sixth transistor Q6 and the second end of the seventh transistor Q7, the first end of the fifteenth capacitor C15 is connected to the second end of the sixth transistor Q6, the third end of the seventh transistor Q7 and the first end of the eighth resistor R8, the second end of the eighth resistor R8 is connected to the output circuit 30, and the second end of the fifteenth capacitor C15 is connected to the third end of the sixth transistor Q6 and then grounded.

[0044] Specifically, the sixth transistor Q6 is an NPN transistor, the seventh transistor Q7 is a PNP transistor, and the eighth resistor R8 is a bias resistor. The main part of the overcurrent protection circuit 20 is composed of the NPN transistor and the PNP transistor. The overcurrent signal is received through the base of the NPN transistor. After being turned on, the PNP transistor is activated together. After both are turned on, the internal current is continuously amplified due to positive feedback, forming a latch. The sixteenth capacitor C16 is connected in parallel at both ends of the NPN transistor, and the fifteenth capacitor C15 is connected in parallel at both ends of the PNP transistor to reduce the voltage change rate to prevent it from being mis-conducted. The current flowing into the PNP transistor is reduced by the bias resistor connected in parallel on the PNP transistor side.

[0045] Continue to refer Figure 4Optionally, the output circuit 30 includes: a transformer T1, a driving unit 31, a switch unit 32, an overcurrent unit 33, a first voltage limiting unit 34 and a second voltage limiting unit 35; the first end of the driving unit 31 is connected to the level conversion circuit 10, the second end of the driving unit 31 is connected to the control end G of the switch unit 32, the first end of the switch unit 32 is connected to the fifth end 5 of the primary side of the transformer T1 and the first end of the first voltage limiting unit 34, the second end of the first voltage limiting unit 34 is connected to the first end of the second voltage limiting unit 35, the second end of the second voltage limiting unit 35 is connected to the third end of the switch unit 32 and the first end of the overcurrent unit 33, and the second end of the overcurrent unit 33 is grounded.

[0046] Continue to refer Figure 4 Optionally, the driving unit 31 includes a tenth resistor R10, the switching unit 32 includes an eighth transistor Q8, the overcurrent unit 33 includes a fifth resistor R5, the first voltage limiting unit 34 includes an eleventh diode D11, and the second voltage limiting unit 35 includes a twelfth diode D12; a first end of the tenth resistor R10 is connected to the level conversion circuit 10, a second end of the tenth resistor R10 is connected to the control end G of the eighth transistor Q8, a first end of the eighth transistor Q8 is connected to the fifth end 5 of the primary side of the transformer T1 and a first end of the eleventh diode D11, a second end of the eleventh diode D11 is connected to a first end of the twelfth diode D12, a second end of the twelfth diode D12 is connected to the third end of the eighth transistor Q8 and a first end of the fifth resistor R5, and a second end of the fifth resistor R5 is grounded.

[0047] Specifically, the fifth resistor R5 is an overcurrent resistor, the tenth resistor R10 is a driving resistor of the eighth transistor Q8, and the eleventh diode D11 and the twelfth diode D12 are used for voltage limiting. The output circuit 30 controls the opening and closing of the eighth transistor Q8 inside it by the PWM wave output by the level conversion circuit 10, and feeds back the overcurrent signal to the overcurrent protection circuit 20 through the voltage of the fifth resistor R5. The protection is triggered at startup, so that the eighth transistor Q8 is turned off. And as the current decreases, the overcurrent protection will recover autonomously, so that the eighth transistor Q8 operates normally, thereby outputting a preset voltage.

[0048] Continue to refer Figure 4Optionally, the output circuit 30 further includes: an eighth capacitor C8, a third diode D3, a first diode D1, a fifth capacitor C5, a sixth capacitor C6, a first resistor R1, a second diode D2, a fourth capacitor C4, a seventh capacitor C7, a fifth diode D5, a ninth capacitor C9, a tenth capacitor C10, a fourth diode D4, a third resistor R3, an eleventh capacitor C11 and a twelfth capacitor C12; the eighth capacitor C8 is connected between the first end 1 and the third end 3 of the primary side of the transformer T1, and the third diode D3 is connected between the first end 1 and the second end 2 of the primary side of the transformer T1; the tenth end 10 of the secondary side of the transformer T1 is connected to the first end of the first diode D1, the second end of the first diode D1 is connected to the first end of the fifth capacitor C5, the first end of the sixth capacitor C6, the first end of the first resistor R1 and the first end of the fourth capacitor C4, the second end of the first resistor R1 is connected to the first end of the second diode D2, the second end of the fourth capacitor C4 is connected to the seventh capacitor C 7 is connected to the first end of the transformer T1, the second end of the first resistor R1 is connected to the second end of the fourth capacitor C4, the second end of the seventh capacitor C7 is connected to the second end of the second diode D2, the second end of the sixth capacitor C6, the second end of the fifth capacitor C5 and the ninth end 9 of the secondary side of the transformer T1; the seventh end 7 of the secondary side of the transformer T1 is connected to the first end of the ninth capacitor C9, the first end of the tenth capacitor C10, the first end of the fourth diode D4 and the first end of the eleventh capacitor C11, the second end of the fourth diode D4 is connected to the first end of the third resistor R3, the second end of the eleventh capacitor C11 is connected to the first end of the twelfth capacitor C12, the second end of the fourth diode D4 is connected to the second end of the eleventh capacitor C11, the second end of the twelfth capacitor C12 is connected to the second end of the third resistor R3, the second end of the tenth capacitor C10, the second end of the ninth capacitor C9 and the first end of the fifth diode D5, and the second end of the fifth diode D5 is connected to the sixth end 6 of the secondary side of the transformer T1.

[0049] Continue to refer Figure 4 Optionally, the overcurrent protection topology also includes: a first capacitor C1, a second capacitor C2 and a third capacitor C3; the first end of the first capacitor C1 is connected to the first end of the second capacitor C2 and the first end of the third capacitor C3 and then connected to the power supply end VCC-12V, and the second end of the first capacitor C1 is connected to the second end of the second capacitor C2 and the second end of the third capacitor C3 and then grounded.

[0050] An embodiment of the utility model further provides an overcurrent protection system, which includes the overcurrent protection topology provided by any embodiment of the utility model.

[0051] Since the overcurrent protection system includes the overcurrent protection topology provided by any embodiment of the utility model, the beneficial effects of the above-mentioned overcurrent protection system and the overcurrent protection topology are the same and will not be repeated here.

[0052] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. An overcurrent protection topology, characterized in that: include: Level conversion circuit, overcurrent protection circuit and output circuit; The level conversion circuit is connected to the output circuit, and the level conversion circuit is used to receive an externally input PWM wave and output a level signal complementary to the PWM wave to the output circuit; The overcurrent protection circuit is connected to the level conversion circuit and the output circuit. The overcurrent protection circuit is used to control the output of the level conversion circuit. The output circuit is used to output a preset voltage.

2. The overcurrent protection topology according to claim 1, characterized in that: The level conversion circuit comprises: a first protection unit, a first switch unit, a voltage dividing unit, a second protection unit and a second switch unit; The first protection unit is connected between the control end and the second end of the first switch unit, the first end of the first switch unit is connected to the first end of the voltage divider unit, the first end of the second protection unit and the first end of the second switch unit, the second end of the voltage divider unit is connected to the second end of the second switch unit and then to the power supply end, and the third end of the second switch unit is connected to the second end of the second protection unit and the output circuit.

3. The overcurrent protection topology according to claim 2, characterized in that: The first protection unit includes a thirteenth diode, the first switch unit includes a tenth transistor, the voltage divider unit includes a ninth resistor, the second protection unit includes a tenth diode, and the second switch unit includes a ninth transistor; The thirteenth diode is connected between the control end and the second end of the tenth transistor, the first end of the tenth transistor is connected to the first end of the ninth resistor, the first end of the tenth diode and the first end of the ninth transistor, the second end of the ninth resistor is connected to the second end of the ninth transistor and then to the power supply end, and the third end of the ninth transistor is connected to the second end of the tenth diode and the output circuit.

4. The overcurrent protection topology according to claim 1, characterized in that: The overcurrent protection circuit comprises: a first filtering unit, a third switching unit, a fourth switching unit and a second filtering unit; The first end of the first filter unit is connected to the level conversion circuit and the first end of the fourth switch unit, the second end of the first filter unit is connected to the first end of the third switch unit and the second end of the fourth switch unit, and the second filter unit is connected to the second end, the third end of the third switch unit, the third end of the fourth switch unit and the output circuit.

5. The overcurrent protection topology according to claim 4, characterized in that: The first filtering unit includes an eleventh resistor and a sixteenth capacitor, the third switch unit includes a sixth transistor, the fourth switch unit includes a seventh transistor, and the second filtering unit includes a fifteenth capacitor and an eighth resistor; The first ends of the eleventh resistor and the sixteenth capacitor are connected to the level conversion circuit and the first end of the seventh transistor, the second ends of the eleventh resistor and the sixteenth capacitor are connected to the first end of the sixth transistor and the second end of the seventh transistor, the first end of the fifteenth capacitor is connected to the second end of the sixth transistor, the third end of the seventh transistor and the first end of the eighth resistor, the second end of the eighth resistor is connected to the output circuit, and the second end of the fifteenth capacitor is connected to the third end of the sixth transistor and then grounded.

6. The overcurrent protection topology according to claim 1, characterized in that: The output circuit comprises: a transformer, a driving unit, a switch unit, an overcurrent unit, a first voltage limiting unit and a second voltage limiting unit; The first end of the driving unit is connected to the level conversion circuit, the second end of the driving unit is connected to the control end of the switch unit, the first end of the switch unit is connected to the fifth end of the primary side of the transformer and the first end of the first voltage limiting unit, the second end of the first voltage limiting unit is connected to the first end of the second voltage limiting unit, the second end of the second voltage limiting unit is connected to the third end of the switch unit and the first end of the overcurrent unit, and the second end of the overcurrent unit is grounded.

7. The overcurrent protection topology according to claim 6, characterized in that: The driving unit includes a tenth resistor, the switch unit includes an eighth transistor, the overcurrent unit includes a fifth resistor, the first voltage limiting unit includes an eleventh diode, and the second voltage limiting unit includes a twelfth diode; The first end of the tenth resistor is connected to the level conversion circuit, the second end of the tenth resistor is connected to the control end of the eighth transistor, the first end of the eighth transistor is connected to the fifth end of the primary side of the transformer and the first end of the eleventh diode, the second end of the eleventh diode is connected to the first end of the twelfth diode, the second end of the twelfth diode is connected to the third end of the eighth transistor and the first end of the fifth resistor, and the second end of the fifth resistor is grounded.

8. The overcurrent protection topology according to claim 6, characterized in that: The output circuit further includes: an eighth capacitor, a third diode, a first diode, a fifth capacitor, a sixth capacitor, a first resistor, a second diode, a fourth capacitor, a seventh capacitor, a fifth diode, a ninth capacitor, a tenth capacitor, a fourth diode, a third resistor, an eleventh capacitor and a twelfth capacitor; The eighth capacitor is connected between the first end and the third end of the primary side of the transformer, and the third diode is connected between the first end and the second end of the primary side of the transformer; The tenth end of the secondary side of the transformer is connected to the first end of the first diode, the second end of the first diode is connected to the first end of the fifth capacitor, the first end of the sixth capacitor, the first end of the first resistor, and the first end of the fourth capacitor, the second end of the first resistor is connected to the first end of the second diode, the second end of the fourth capacitor is connected to the first end of the seventh capacitor, the second end of the first resistor is connected to the second end of the fourth capacitor, and the second end of the seventh capacitor is connected to the second end of the second diode, the second end of the sixth capacitor, the second end of the fifth capacitor, and the ninth end of the secondary side of the transformer; The seventh end of the secondary side of the transformer is connected to the first end of the ninth capacitor, the first end of the tenth capacitor, the first end of the fourth diode and the first end of the eleventh capacitor, the second end of the fourth diode is connected to the first end of the third resistor, the second end of the eleventh capacitor is connected to the first end of the twelfth capacitor, the second end of the fourth diode is connected to the second end of the eleventh capacitor, the second end of the twelfth capacitor is connected to the second end of the third resistor, the second end of the tenth capacitor, the second end of the ninth capacitor and the first end of the fifth diode, and the second end of the fifth diode is connected to the sixth end of the secondary side of the transformer.

9. The overcurrent protection topology according to claim 1, characterized in that: Also includes: a first capacitor, a second capacitor and a third capacitor; The first end of the first capacitor is connected to the first end of the second capacitor and the first end of the third capacitor and then connected to the power supply end, and the second end of the first capacitor is connected to the second end of the second capacitor and the second end of the third capacitor and then grounded.

10. An overcurrent protection system, characterized in that: Includes the overcurrent protection topology described in any one of claims 1-9.

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