A lightning protection circuit and switching power supply

Abstract

The application relates to a lightning protection circuit and a switching power supply, wherein the circuit comprises a first lightning protection module and a second lightning protection module, the input end of the first lightning protection module is connected with a power supply, the output end of the first lightning protection module is connected with the input end of the second lightning protection module, and the output end of the second lightning protection module is connected with a subsequent circuit; wherein the first lightning protection module comprises a first fuse and a first voltage-dependent resistor connected in series; and the second lightning protection module comprises a second fuse and a second voltage-dependent resistor connected in series. Through the application, the problem that a lightning protection circuit cannot simultaneously have high lightning protection efficiency and low cost is solved.

Description

Technical Field

[0001] This application relates to the field of power supplies, and in particular to a surge protection circuit and a switching power supply. Background Technology

[0002] In related technologies, surge protection circuits typically consist of a single surge protection unit, which often results in inadequate protection. During a lightning strike, components may smoke or burn, damaging subsequent circuits. To achieve better surge protection, an external surge protector is usually connected to the load. However, surge protectors are not only bulky but also expensive.

[0003] Currently, no effective solution has been proposed to address the issue that surge protection circuits in related technologies cannot simultaneously achieve both high-efficiency surge protection and low cost. Utility Model Content

[0004] This application provides a surge protection circuit and a switching power supply to at least solve the problem in related technologies that surge protection circuits cannot simultaneously achieve high-efficiency surge protection and low cost.

[0005] In a first aspect, embodiments of this application provide a surge protection circuit, the circuit comprising: a primary surge protection module and a secondary surge protection module, wherein the input terminal of the primary surge protection module is connected to a power supply, the output terminal of the primary surge protection module is connected to the input terminal of the secondary surge protection module, and the output terminal of the secondary surge protection module is connected to a subsequent circuit; wherein,

[0006] The primary lightning protection module includes a first fuse and a first varistor connected in series;

[0007] The secondary lightning protection module includes a second fuse and a second varistor connected in series.

[0008] In some embodiments, the primary surge protection module further includes a second fuse; wherein,

[0009] The first fuse, the second fuse, and the first varistor are connected in series, and the second fuse is connected to the live wire of the power supply, while the first varistor is connected to the neutral wire of the power supply.

[0010] In some embodiments, the primary surge protection module further includes a thermistor; wherein,

[0011] The first fuse, the first varistor, and the thermistor are connected in series, and the first fuse is connected to the live wire of the power supply, while the thermistor is connected to the neutral wire of the power supply.

[0012] In some embodiments, the primary surge protection module further includes a second fuse and a thermistor; wherein,

[0013] The first fuse, the second fuse, the first varistor, and the thermistor are connected in series, and the second fuse is connected to the live wire of the power supply, and the thermistor is connected to the neutral wire of the power supply.

[0014] In some embodiments, the circuit further includes: an electromagnetic interference suppression module, wherein the output terminal of the primary surge protection module is connected to the input terminal of the electromagnetic interference suppression module, and the output terminal of the electromagnetic interference suppression module is connected to the input terminal of the secondary surge protection module; wherein,

[0015] The electromagnetic interference suppression module includes a conjugate inductor.

[0016] In some embodiments, the electromagnetic interference suppression module includes a first conjugate inductor and a second conjugate inductor; wherein,

[0017] The first conjugate inductor and the second conjugate inductor are connected in series.

[0018] In some embodiments, the electromagnetic interference suppression module further includes a first capacitor unit and a second capacitor unit; wherein,

[0019] The first end of the second capacitor unit is connected to the first current input terminal of the first conjugate inductor, and the second end of the second capacitor unit is connected to the second current input terminal of the first conjugate inductor.

[0020] The first end of the first capacitor unit is connected to the first current output terminal of the first conjugate inductor and the first current input terminal of the second conjugate inductor, and the second end of the first capacitor unit is connected to the second current output terminal of the first conjugate inductor and the second current input terminal of the second conjugate inductor.

[0021] In some embodiments, the electromagnetic interference suppression module further includes a resistor unit;

[0022] The first end of the resistor unit is connected to the first end of the second capacitor unit and the first current input end of the first conjugate inductor, respectively.

[0023] The second end of the resistor unit is connected to the second end of the second capacitor unit and the second current input end of the first conjugate inductor, respectively.

[0024] In some embodiments, the subsequent circuitry includes a switching circuit.

[0025] Secondly, embodiments of this application provide a switching power supply, which includes the surge protection circuit and switching circuit described in the first aspect above.

[0026] Compared to related technologies, the surge protection circuit and switching power supply provided in this application embodiment form a two-stage surge protection module through a first fuse and a first varistor, and a second fuse and a second varistor, respectively. This module absorbs lightning energy and effectively prevents damage to downstream circuits during lightning strikes. Furthermore, by reducing the in-loop current of the first and second varistors through the first and second fuses, the surge protection capability is further improved while maintaining low cost. This solves the problem that surge protection circuits cannot simultaneously achieve both high-efficiency surge protection capability and low cost.

[0027] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0029] Figure 1 This is a schematic diagram of a lightning protection circuit in one embodiment of this application;

[0030] Figure 2 This is a schematic diagram of a primary lightning protection module in one embodiment of this application;

[0031] Figure 3 This is a schematic diagram of an electromagnetic interference suppression module in one embodiment of this application;

[0032] Figure 4 This is a schematic diagram of a flyback power supply surge protection circuit in one embodiment of this application;

[0033] Figure 5 This is a schematic diagram of a switching power supply according to one embodiment of this application.

[0034] Figure reference numerals: 1. Lightning protection circuit; 11. Primary lightning protection module; 12. Secondary lightning protection module; 13. Electromagnetic interference suppression module; 131. First capacitor unit; 132. Second capacitor unit; 133. Resistor unit; 2. Switching circuit; FU1. First fuse; FU2. First fuse; FU3. Third fuse; RV1. First varistor; RV2. Second varistor; RT1. Thermistor; R1. First resistor; R2. Second resistor; CX1. First capacitor; CX2. Second capacitor; CM1. First conjugate inductor; CM2. Second conjugate inductor. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application. Furthermore, it is understood that although the efforts made in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, modifications to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0036] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0037] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application means two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The terms “first,” “second,” “third,” etc., used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0038] This embodiment provides a surge protection circuit 1, including: a primary surge protection module 11 and a secondary surge protection module 12. The input terminal of the primary surge protection module 11 is connected to a power supply, the output terminal of the primary surge protection module 11 is connected to the input terminal of the secondary surge protection module 12, and the output terminal of the secondary surge protection module 12 is connected to a subsequent circuit. The primary surge protection module 11 includes a first fuse FU1 and a first varistor RV1 connected in series; the secondary surge protection module 12 includes a second fuse FU2 and a second varistor RV2 connected in series.

[0039] In the primary surge protection module 11, the first fuse FU1 and the second fuse FU2 limit the current, disconnecting the circuit connection when the current abnormally increases to prevent lightning strikes from causing overload or short circuits and damaging subsequent circuits. The first varistor RV1 absorbs primary lightning energy, and the second varistor RV2 absorbs secondary lightning energy. When the voltage in the circuit exceeds the threshold voltage of the varistor, the varistor reduces its resistance, allowing the lightning energy to be directed to the ground. The first fuse FU1 and the second fuse FU2, as well as the first varistor RV1 and the second varistor RV2, can be of the same or different types; no restriction is placed here. Because the second fuse FU2 and the third fuse FU3 are connected in series, the loop current of the first varistor RV1 and the second varistor RV2 can be limited.

[0040] Optionally, Figure 1 A schematic diagram of a lightning protection circuit 1 is provided, as follows: Figure 1 As shown, when the primary surge protection module 11 includes a first fuse FU1 and a first varistor RV1 connected in series, the first end of the first fuse FU1 is connected to the live wire of the power supply, the second end of the first fuse FU1 is connected to the first end of the first varistor RV1, and the second end of the first varistor RV1 is connected to the neutral wire of the power supply. When the secondary surge protection module 12 includes a second fuse FU2 and a second varistor RV2 connected in series, the first end of the second fuse FU2 is connected to the first end of the first fuse FU1, the second end of the second fuse FU2 is connected to the first end of the second varistor RV2, and the second end of the second varistor RV2 is connected to the second end of the first varistor RV1.

[0041] In this embodiment, through the design of a two-stage lightning protection module, if a large amount of electrical energy is still left after the first-stage lightning protection module 11 limits the circuit current and absorbs lightning energy, the second-stage lightning protection module 12 can further limit the circuit current and absorb lightning energy, achieving low cost and enhanced lightning protection effect, which can effectively protect the subsequent circuits.

[0042] In some embodiments, the primary surge protection module 11 further includes a second fuse FU2; wherein the first fuse FU1, the second fuse FU2 and the first varistor RV1 are connected in series, and the second fuse FU2 is connected to the live wire of the power supply, and the first varistor RV1 is connected to the neutral wire of the power supply.

[0043] In this design, by connecting the second fuse FU2 to the live wire of the power supply, the second fuse FU2 not only provides overcurrent protection but also limits current. Optionally, when the primary surge protection module 11 includes a first fuse FU1, a second fuse FU2, and a first varistor RV1, the first end of the second fuse FU2 is connected to the live wire of the power supply, the second end of the second fuse FU2 is connected to the first end of the first fuse FU1, the second end of the first fuse FU1 is connected to the first end of the first varistor RV1, and the second end of the first varistor RV1 is connected to the neutral wire of the power supply. In this case, in the secondary surge protection module 12, the first end of the second fuse FU2 remains connected to the first end of the first fuse FU1, and the second end of the second fuse FU2 remains connected to the first end of the second varistor RV2.

[0044] In this embodiment, the first fuse FU1, the second fuse FU2, and the first varistor RV1 connected in series can achieve hierarchical protection for the downstream circuit, while absorbing lightning energy and further improving the lightning protection capability.

[0045] In some embodiments, the primary surge protection module 11 further includes a thermistor RT1; wherein the first fuse FU1, the first varistor RV1 and the thermistor RT1 are connected in series, and the first fuse FU1 is connected to the live wire of the power supply, and the thermistor RT1 is connected to the neutral wire of the power supply.

[0046] The thermistor RT1 is used to limit surge current. When struck by lightning, the lightning protection circuit receives a large amount of electrical energy, which may cause a surge. The resistance of the thermistor RT1 changes with temperature, and this change in resistance suppresses the surge. Optionally, to improve the limitation of surge current, the thermistor RT1 can be a negative temperature coefficient thermistor. Optionally, when the primary surge protection module 11 includes a first fuse FU1, a first varistor RV1, and a thermistor RT1, the first terminal of the first fuse FU1 is connected to the live wire of the power supply, the second terminal of the first fuse FU1 is connected to the first terminal of the first varistor RV1, the second terminal of the first varistor RV1 is connected to the first terminal of the thermistor RT1, and the second terminal of the thermistor RT1 is connected to the neutral wire of the power supply. In this case, the first terminal of the second fuse FU2 in the secondary surge protection module 12 remains connected to the first terminal of the first fuse FU1, and the second terminal of the second fuse FU2 remains connected to the first terminal of the second varistor RV2.

[0047] In this embodiment, the first fuse FU1, the first varistor RV1, and the thermistor RT1 can absorb lightning energy and prevent surge current, thereby improving the lightning protection capability.

[0048] In some embodiments, the primary surge protection module 11 further includes a second fuse FU2 and a thermistor RT1; wherein the first fuse FU1, the second fuse FU2, the first varistor RV1 and the thermistor RT1 are connected in series, and the second fuse FU2 is connected to the live wire of the power supply, and the thermistor RT1 is connected to the neutral wire of the power supply.

[0049] Figure 2 A schematic diagram of a primary surge protection module 11 is provided, as shown below. Figure 2 As shown, the first end of the second fuse FU2 is connected to the live wire of the power supply, and the second end of the second fuse FU2 is connected to the first end of the first fuse FU1; the second end of the first fuse FU1 is connected to the first end of the varistor, the second end of the varistor is connected to the first end of the thermistor RT1, and the second end of the thermistor RT1 is connected to the neutral wire of the power supply.

[0050] In this embodiment, by simultaneously setting a second fuse FU2 and a thermistor RT1 in the primary lightning protection module 11, overcurrent protection can be provided by the second fuse FU2, while surge current can be limited by the thermistor RT1, effectively preventing damage to components in the subsequent circuit during lightning strikes.

[0051] In some embodiments, the circuit further includes: an electromagnetic interference suppression module 13, wherein the output terminal of the primary surge protection module 11 is connected to the input terminal of the electromagnetic interference suppression module 13, and the output terminal of the electromagnetic interference suppression module 13 is connected to the input terminal of the secondary surge protection module 12; wherein the electromagnetic interference suppression module 13 includes a conjugate inductor.

[0052] A conjugate inductor, also known as a common-mode choke, can suppress common-mode noise. In applications requiring high common-mode noise suppression, such as switching power supplies, AC power filters, and data communication lines, a conjugate inductor can suppress electromagnetic interference and reduce the susceptibility of the downstream circuitry to external interference.

[0053] The electromagnetic interference suppression module 13 may include one conjugate inductor, or it may include two or more conjugate inductors connected in series. Optionally, in some embodiments, the electromagnetic interference suppression module 13 includes a first conjugate inductor CM1 and a second conjugate inductor CM2; wherein the first conjugate inductor CM1 and the second conjugate inductor CM2 are connected in series. By connecting two common-mode chokes in series, the impedance to common-mode noise can be increased, thereby more effectively suppressing unwanted noise signals. Optionally, the first conjugate inductor CM1 and the second conjugate inductor CM2 can be selected from different models, so that the first conjugate inductor CM1 and the second conjugate inductor CM2 can suppress noise in different frequency ranges respectively. By connecting two common-mode chokes in series, effective noise suppression can be achieved over a wider frequency range.

[0054] Furthermore, in some embodiments, the electromagnetic interference suppression module 13 further includes a first capacitor unit 131 and a second capacitor unit 132; wherein, the first end of the second capacitor unit 132 is connected to the first current input terminal of the first conjugate inductor CM1, and the second end of the second capacitor unit 132 is connected to the second current input terminal of the first conjugate inductor CM1; the first end of the first capacitor unit 131 is connected to the first current output terminal of the first conjugate inductor CM1 and the first current input terminal of the second conjugate inductor CM2, and the second end of the first capacitor unit 131 is connected to the second current output terminal of the first conjugate inductor CM1 and the second current input terminal of the second conjugate inductor CM2.

[0055] The second capacitor unit 132 may include one or more capacitors. Connecting the two current input terminals of the first conjugate inductor CM1 to the two terminals of the second capacitor unit 132 enhances the ability to suppress electromagnetic interference and expands the operating frequency band of the first conjugate inductor CM1. Adding capacitors with appropriate parameters can also help absorb voltage spikes and transient phenomena. Similarly, the first capacitor unit 131 may also include one or more capacitors. Connecting the two current output terminals of the first conjugate inductor CM1 and the two current input terminals of the second conjugate inductor CM2 to the two terminals of the second capacitor unit 132 can also improve the ability of the electromagnetic interference suppression module 13 to prevent electromagnetic interference.

[0056] In this embodiment, by setting a first capacitor unit 131 and a second capacitor unit 132 in the electromagnetic interference suppression module 13, they can work together with the first conjugate inductor CM1 and the second conjugate inductor CM2 to reduce the impact of electromagnetic interference on the subsequent circuit.

[0057] Furthermore, in some embodiments, the electromagnetic interference suppression module 13 further includes a resistor unit 133; the first end of the resistor unit 133 is connected to the first end of the second capacitor unit 132 and the first current input terminal of the first conjugate inductor CM1, respectively; the second end of the resistor unit 133 is connected to the second end of the second capacitor unit 132 and the second current input terminal of the first conjugate inductor CM1, respectively.

[0058] The resistor unit 133 may include a single resistor or two or more resistors connected in series. When the load is struck by lightning, the resistor unit 133 can discharge the energy, reducing the possibility that excessive electrical energy may damage the components in the electromagnetic interference suppression module 13 if the first-level lightning protection module 11 cannot fully release the electrical energy.

[0059] Optionally, Figure 3 A schematic diagram of an electromagnetic interference suppression module 13 is provided, as shown below. Figure 3 As shown, the electromagnetic interference suppression module 13 includes a first conjugate inductor CM1, a second conjugate inductor CM2, a first capacitor unit 131, a second capacitor unit 132, and a resistor unit 133. The first terminal of the second capacitor unit 132 is connected to the first current input terminal of the first conjugate inductor CM1 and the first terminal of the resistor unit 133; the second terminal of the second capacitor unit 132 is connected to the second current input terminal of the first conjugate inductor CM1 and the second terminal of the resistor unit 133. The first terminal of the first capacitor unit 131 is connected to the first current output terminal of the first conjugate inductor CM1 and the first current input terminal of the second conjugate inductor CM2; the second terminal of the first capacitor unit 131 is connected to the second current output terminal of the first conjugate inductor CM1 and the second current input terminal of the second conjugate inductor CM2.

[0060] In some embodiments, the subsequent circuit includes a switching circuit 2. Optionally, the subsequent circuit is a switching circuit 2, which includes a switching element, a load, a rectifier circuit, etc. Optionally, combining the surge protection circuit 1 and the subsequent circuit can constitute a flyback switching power supply.

[0061] In flyback power supplies of related technologies, the surge protection circuit 1 is generally composed of a single-stage surge protection unit, resulting in unsatisfactory surge protection performance. During a lightning strike, the downstream rectifier diodes are easily damaged, and phenomena such as smoke and burning of the varistor often occur. In one embodiment, Figure 4 A schematic diagram of a flyback power supply surge protection circuit is provided, such as... Figure 4 As shown, J1 is the AC mains input interface, with a voltage range of AC200~240V.

[0062] In the primary surge protection module 11, the following components are selected: a first fuse FU1 (model A250-200 / PTC / 10A), a second resistance-maintaining wire FU2 (model 250V / 2A), a third fuse FU3 (model A250-200 / PTC / 10A), a thermistor RT1 (model 3D-9 / NTC / 5Ω), a first varistor RV1 (model 10D471K), and a second varistor RV2 (model 10D471K). The first terminal of the second resistance-maintaining wire FU2 is connected in series with the mains line L, and the second terminal of FU2 is connected to FU2, primarily for overcurrent protection. The first terminal of the first fuse FU1 is connected in series with the second terminal of the second resistance-maintaining wire FU2, and the second terminal is connected in series with the varistor RV1, primarily for current limiting. The first terminal of the first varistor RV1 is connected in series with the first fuse FU1, and the second terminal of the first varistor RV1 is connected to the first terminal of the thermistor RT1, primarily for absorbing primary lightning energy. The second terminal of the thermistor RT1 is connected in series with the neutral (N) line of the mains power supply, and its main function is to limit surge current.

[0063] In the electromagnetic interference suppression module 13, the resistor unit 133 includes a first resistor R1 and a second resistor R2 connected in series. The resistance of the first resistor R1 is 1.2M ohms, and the resistance of the second resistor R2 is 1.2M ohms. A second capacitor CX2 of type 105 / 310V is selected as the second capacitor unit 132, and a first capacitor CX1 of type 473 / 310V is selected as the first capacitor unit 131. The second capacitor unit 132 is connected in parallel with the resistor unit 133. Furthermore, the first terminal of the second capacitor CX2 is connected to pin 3 (the first current input terminal) of the first conjugate inductor CM1, and the second terminal of the second capacitor CX2 is connected to pin 1 (the second current input terminal) of the first conjugate inductor CM1. The first terminal of the first capacitor CX1 is connected to pin 3 (first current output terminal) of the first conjugate inductor CM1 and pin 4 (first current input terminal) of the second conjugate inductor CM2. The second terminal of the first capacitor CX1 is connected to pin 2 (second current output terminal) of the first conjugate inductor CM1 and pin 1 (second current input terminal) of the second conjugate inductor CM2.

[0064] In the secondary surge protection module 12, a PTC / 10A third fuse FU3 and a 10D471K second varistor RV2 are selected. The second terminal of the third fuse FU3 is connected in series with the second varistor RV2, and the first terminal of the third fuse FU3 is connected to pin 3 of the second conjugate inductor CM2, mainly for current limiting. The first terminal of the second varistor RV2 is connected in series with the third fuse FU3, and the second terminal of the second varistor RV2 is connected to pin 2 of the second conjugate inductor CM2, mainly for absorbing secondary lightning energy.

[0065] The subsequent circuit includes rectifier diodes D1, D2, D3, and D4, and capacitor C1. The first terminal of the third fuse FU3 is connected to the positive terminal of rectifier diode D1 and the negative terminal of rectifier diode D3. The negative terminal of D1 is connected to the negative terminal of D2. The second terminal of the second varistor RV2 is connected to the positive terminal of rectifier diode D2 and the negative terminal of rectifier diode D4. The positive terminals of rectifier diodes D4 and D3 are grounded. One end of capacitor C1 is connected to the negative terminal of D2, and the other end of capacitor C1 is grounded. The subsequent circuit outputs DC power.

[0066] It is understandable that, depending on the actual application requirements, the device in this embodiment can also be replaced with other models of devices.

[0067] In this embodiment, the first varistor RV1, the second varistor RV2, the first fuse FU1, the second fuse FU2, the third fuse FU3, and the thermistor RT1 form a two-stage lightning protection unit, effectively preventing damage to rectifier diodes D1, D2, D3, and D4, as well as subsequent components, during lightning strikes. Furthermore, by connecting the second fuse FU2 and the third fuse FU3 in series, the loop current of the first varistor RV1 and the second varistor RV2 is reduced, lowering the possibility of the first varistor RV1 and the second varistor RV2 exploding, smoking, or burning due to the large current during a lightning strike.

[0068] This embodiment also provides a switching power supply, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the terms "module," "unit," "subunit," etc., can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0069] In one embodiment, Figure 5 A schematic diagram of a switching power supply is provided, such as... Figure 5 As shown, the switching power supply includes a surge protection circuit 1 and a switching circuit 2.

[0070] In one embodiment, the surge protection circuit 1 includes a primary surge protection module 11 and a secondary surge protection module 12. The input terminal of the primary surge protection module 11 is connected to a power supply, the output terminal of the primary surge protection module 11 is connected to the input terminal of the secondary surge protection module 12, and the output terminal of the secondary surge protection module 12 is connected to a subsequent circuit. The primary surge protection module 11 includes a first fuse FU1 and a first varistor RV1 connected in series; the secondary surge protection module 12 includes a second fuse FU2 and a second varistor RV2 connected in series. The subsequent circuit includes a switching circuit 2.

[0071] Optionally, the primary surge protection module 11 also includes a second fuse FU2; wherein the first fuse FU1, the second fuse FU2 and the first varistor RV1 are connected in series, and the second fuse FU2 is connected to the live wire of the power supply, and the first varistor RV1 is connected to the neutral wire of the power supply.

[0072] Optionally, the primary surge protection module 11 also includes a thermistor RT1; wherein the first fuse FU1, the first varistor RV1 and the thermistor RT1 are connected in series, and the first fuse FU1 is connected to the live wire of the power supply, and the thermistor RT1 is connected to the neutral wire of the power supply.

[0073] Optionally, the primary surge protection module 11 also includes a second fuse FU2 and a thermistor RT1; wherein the first fuse FU1, the second fuse FU2, the first varistor RV1 and the thermistor RT1 are connected in series, and the second fuse FU2 is connected to the live wire of the power supply, and the thermistor RT1 is connected to the neutral wire of the power supply.

[0074] In one embodiment, the circuit further includes an electromagnetic interference suppression module 13, wherein the output terminal of the primary surge protection module 11 is connected to the input terminal of the electromagnetic interference suppression module 13, and the output terminal of the electromagnetic interference suppression module 13 is connected to the input terminal of the secondary surge protection module 12; wherein the electromagnetic interference suppression module 13 includes a conjugate inductor.

[0075] Optionally, the electromagnetic interference suppression module 13 includes a first conjugate inductor CM1 and a second conjugate inductor CM2; wherein the first conjugate inductor CM1 and the second conjugate inductor CM2 are connected in series.

[0076] Optionally, the electromagnetic interference suppression module 13 further includes a first capacitor unit 131 and a second capacitor unit 132; wherein, the first end of the second capacitor unit 132 is connected to the first current input terminal of the first conjugate inductor CM1, and the second end of the second capacitor unit 132 is connected to the second current input terminal of the first conjugate inductor CM1; the first end of the first capacitor unit 131 is connected to the first current output terminal of the first conjugate inductor CM1 and the first current input terminal of the second conjugate inductor CM2, and the second end of the first capacitor unit 131 is connected to the second current output terminal of the first conjugate inductor CM1 and the second current input terminal of the second conjugate inductor CM2.

[0077] Optionally, the electromagnetic interference suppression module 13 further includes a resistor unit 133; the first end of the resistor unit 133 is connected to the first end of the second capacitor unit 132 and the first current input terminal of the first conjugate inductor CM1 respectively; the second end of the resistor unit 133 is connected to the second end of the second capacitor unit 132 and the second current input terminal of the first conjugate inductor CM1 respectively.

[0078] It should be noted that the above modules are implemented in hardware, and the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0079] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A lightning protection circuit, characterized in that, The circuit includes: a primary surge protection module and a secondary surge protection module. The input terminal of the primary surge protection module is connected to the power supply, the output terminal of the primary surge protection module is connected to the input terminal of the secondary surge protection module, and the output terminal of the secondary surge protection module is connected to the subsequent circuit. The primary lightning protection module includes a first fuse and a first varistor connected in series; The secondary lightning protection module includes a second fuse and a second varistor connected in series.

2. The lightning protection circuit according to claim 1, characterized in that, The primary lightning protection module also includes a second fuse; wherein... The first fuse, the second fuse, and the first varistor are connected in series, and the second fuse is connected to the live wire of the power supply, while the first varistor is connected to the neutral wire of the power supply.

3. The lightning protection circuit according to claim 1, characterized in that, The primary surge protection module also includes a thermistor; wherein... The first fuse, the first varistor, and the thermistor are connected in series, and the first fuse is connected to the live wire of the power supply, while the thermistor is connected to the neutral wire of the power supply.

4. The lightning protection circuit according to claim 1, characterized in that, The primary surge protection module also includes a second fuse and a thermistor; wherein... The first fuse, the second fuse, the first varistor, and the thermistor are connected in series, and the second fuse is connected to the live wire of the power supply, and the thermistor is connected to the neutral wire of the power supply.

5. The lightning protection circuit according to claim 1, characterized in that, The circuit further includes: an electromagnetic interference suppression module, wherein the output terminal of the primary surge protection module is connected to the input terminal of the electromagnetic interference suppression module, and the output terminal of the electromagnetic interference suppression module is connected to the input terminal of the secondary surge protection module; wherein, The electromagnetic interference suppression module includes a conjugate inductor.

6. The lightning protection circuit according to claim 5, characterized in that, The electromagnetic interference suppression module includes a first conjugate inductor and a second conjugate inductor; wherein... The first conjugate inductor and the second conjugate inductor are connected in series.

7. The lightning protection circuit according to claim 6, characterized in that, The electromagnetic interference suppression module further includes a first capacitor unit and a second capacitor unit; wherein... The first end of the second capacitor unit is connected to the first current input terminal of the first conjugate inductor, and the second end of the second capacitor unit is connected to the second current input terminal of the first conjugate inductor. The first end of the first capacitor unit is connected to the first current output terminal of the first conjugate inductor and the first current input terminal of the second conjugate inductor, and the second end of the first capacitor unit is connected to the second current output terminal of the first conjugate inductor and the second current input terminal of the second conjugate inductor.

8. The lightning protection circuit according to claim 6 or 7, characterized in that, The electromagnetic interference suppression module also includes a resistor unit; The first end of the resistor unit is connected to the first end of the second capacitor unit and the first current input end of the first conjugate inductor, respectively. The second end of the resistor unit is connected to the second end of the second capacitor unit and the second current input end of the first conjugate inductor, respectively.

9. The lightning protection circuit according to claim 1, characterized in that, The subsequent circuitry includes a switching circuit.

10. A switching power supply, characterized in that, The switching power supply includes: the surge protection circuit and the switching circuit as described in any one of claims 1 to 9.

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