CN219086800U - Surge protection circuit and switching power supply - Google Patents

Abstract

The embodiment of the utility model discloses a surge protection circuit and a switching power supply, wherein the circuit comprises a differential mode surge suppression circuit and a common mode surge suppression circuit; the differential mode surge suppression circuit comprises a fuse tube FU1, a piezoresistor RV1, a thermistor RT1, a capacitor C2 and an inductor LB1; the common-mode surge suppression circuit comprises a piezoresistor RV2, a piezoresistor RV3, a capacitor C3 and a capacitor C4. The utility model can protect the switch power supply when bearing surge voltage, avoid the interference of the switch power supply to other equipment when bearing interference, enhance the anti-risk capability of the electric power automation device under the condition of occurrence of surge voltage, prevent leakage current from flowing back to the ground to cause electric shock hidden trouble to field operators, has simple structure, reduces the use quantity of components, and is a universal component, low in cost, stable and reliable and suitable for popularization and application.

Description

Surge protection circuit and switching power supply

Technical Field

The embodiment of the utility model relates to the technical field of switching power supplies, in particular to a surge protection circuit and a switching power supply.

Background

For the switching power supply, in order to restrain the influence of input surge current and lightning stroke, before the energy enters the equipment, the energy is either clamped and weakened or discharged to the ground, so that the self-protection capability of the switching power supply during the period is effectively ensured, and the anti-risk capability of the matched power automation device under the condition of surge voltage is further enhanced. As shown in figure 1, for the common-mode voltage generated during lightning surge, a bleeder circuit is formed by a piezoresistor RV2, a piezoresistor RV3, a gas discharge tube BK1 and a resistor R1 pair FG, namely a common-mode wave suppression circuit, when common-mode overvoltage energy enters from L and N, the common-mode voltage is directly added to the piezoresistor RV2, the piezoresistor RV3, the gas discharge tube BK1 and the resistor R1 after passing through a differential-mode part, and if the common-mode voltage exceeds the threshold value of the piezoresistor, the current flowing through the piezoresistor RV2 and the piezoresistor RV3 rises sharply, and the piezoresistor RV2 and the piezoresistor RV3 are equivalent to resistors with infinitesimal resistance values; the common mode voltage will continue to be applied to the gas discharge tube BK1, and when the voltage across the gas discharge tube BK1 reaches its own trigger voltage, the gas gap of the gas discharge tube BK1 breaks down by the high voltage, at which time it can be considered that the gas discharge tube BK1 is shorted and most of the energy is discharged, while the resistor R1 provides a freewheel loop for the residual voltage on the gas discharge tube BK1, so that the voltage will recover to the off state after the disturbance passes, and isolate the piezoresistors RV2, RV3 and FG. The traditional surge protection circuit is complex in structure, more components are used, the distributed capacitance of the middle piezoresistor can interfere a communication loop of the power automation device, and the electric shock risk of field operators is greatly increased by leakage current.

The above problems are to be solved.

Disclosure of Invention

In order to solve the related technical problems, the utility model provides a surge protection circuit and a switching power supply, which solve the problems mentioned in the background art section.

In order to achieve the above purpose, the embodiment of the present utility model adopts the following technical scheme:

in a first aspect, an embodiment of the present utility model provides a surge protection circuit, the circuit including a differential mode surge suppression circuit and a common mode surge suppression circuit; the differential mode surge suppression circuit comprises a fuse tube FU1, a piezoresistor RV1, a thermistor RT1, a capacitor C2 and an inductor LB1; the common-mode surge suppression circuit comprises a piezoresistor RV2, a piezoresistor RV3, a capacitor C3 and a capacitor C4; one end of the fuse FU1 is connected with a mains supply wire end, the other end of the fuse is connected with one end of the piezoresistor RV1 and one end of the thermistor RT1, the other end of the piezoresistor RV1 is connected with a mains supply zero wire end, one end of the capacitor C2, one end of the piezoresistor RV3 and a first wiring end of the inductor LB1, the other end of the piezoresistor RV3 is connected with a second wiring end of the inductor LB1, one end of the capacitor C1 and a first alternating current pin of the rectifier bridge BR1, the other end of the thermistor RT1 is connected with the other end of the capacitor C2, one end of the piezoresistor RV2 and a third wiring end of the inductor LB1, the other end of the piezoresistor RV2 is connected with a fourth wiring end of the inductor LB1, the other end of the capacitor C1, one end of the capacitor C4 and a second alternating current pin of the rectifier bridge BR1, and the other end of the capacitor C3 is connected with the other end of the capacitor C4 and then connected with an FG end.

As an alternative embodiment, both the capacitor C1 and the capacitor C2 use a safety capacitor.

In a second aspect, an embodiment of the present utility model provides a switching power supply, where the surge protection circuit according to any one of the first aspect is used.

The technical scheme of the embodiment of the utility model ensures that the switching power supply can protect the switching power supply when bearing surge voltage, avoids the interference of the switching power supply to other equipment when bearing interference, enhances the anti-risk capability of the electric power automation device under the condition of occurrence of surge voltage, prevents leakage current from flowing back to the ground to cause electric shock hidden danger to field operators, has simple structure, reduces the use quantity of components, has low cost, is stable and reliable, and is suitable for popularization and application.

Drawings

For a clearer description and understanding of the technical solutions of the embodiments of the present utility model, the following description will make a brief introduction to the drawings required for the description of the embodiments of the present utility model, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to the contents of the embodiments of the present utility model and the drawings without inventive effort for those skilled in the art.

FIG. 1 is a block diagram of a conventional surge protection circuit;

fig. 2 is a schematic diagram of a surge protection circuit according to an embodiment of the present utility model.

Detailed Description

In order to make the technical problems solved by the present utility model, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present utility model will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to fall within the scope of the utility model.

Example 1

Referring to fig. 2, fig. 2 is a schematic diagram of a surge protection circuit according to an embodiment of the present utility model.

The surge protection circuit in the embodiment comprises a differential mode surge suppression circuit and a common mode surge suppression circuit; the differential mode surge suppression circuit comprises a fuse tube FU1, a piezoresistor RV1, a thermistor RT1, a capacitor C2 and an inductor LB1; the common-mode surge suppression circuit comprises a piezoresistor RV2, a piezoresistor RV3, a capacitor C3 and a capacitor C4; one end of the fuse FU1 is connected with a mains supply wire end, the other end of the fuse is connected with one end of the piezoresistor RV1 and one end of the thermistor RT1, the other end of the piezoresistor RV1 is connected with a mains supply zero wire end, one end of the capacitor C2, one end of the piezoresistor RV3 and a first wiring end of the inductor LB1, the other end of the piezoresistor RV3 is connected with a second wiring end of the inductor LB1, one end of the capacitor C1 and a first alternating current pin of the rectifier bridge BR1, the other end of the thermistor RT1 is connected with the other end of the capacitor C2, one end of the piezoresistor RV2 and a third wiring end of the inductor LB1, the other end of the piezoresistor RV2 is connected with a fourth wiring end of the inductor LB1, the other end of the capacitor C1, one end of the capacitor C4 and a second alternating current pin of the rectifier bridge BR1, and the other end of the capacitor C3 is connected with the other end of the capacitor C4 and then connected with an FG end.

Illustratively, in this embodiment, the capacitor C1 and the capacitor C2 are both ampere capacitors.

Specifically, in this embodiment, the differential mode surge suppression circuit is composed of a fuse FU1, a varistor RV1, a thermistor RT1, a capacitor C2, and an inductor LB1, when differential mode energy comes in from the mains supply L, N, the differential mode voltage is directly superimposed on the varistor RV1 through the fuse FU1 and the varistor RV1, at this time, the varistor RV1 weakens the differential mode energy and clamps the differential mode energy in the threshold voltage range of the varistor RV1, and the thermistor RT1, the capacitor C2, and the inductor LB1 further suppress differential mode surge current, so that the fuse FU1 protects the whole differential mode loop, thereby protecting the subsequent devices from being damaged by the superposition of differential mode voltages. The common-mode surge suppression circuit in the embodiment is composed of a piezoresistor RV2, a piezoresistor RV3, a capacitor C3 and a capacitor C4; the piezoresistor RV2 and the piezoresistor RV3 are connected in parallel at two ends of the inductor LB1, so that the energy of common-mode voltage can be effectively weakened, the capacitor C3 and the capacitor C4 provide a discharging loop for FG, leakage current of the capacitor C3 and leakage current of the capacitor C4 can exist in a circuit, and the piezoresistor RV2 and the piezoresistor RV3 in FIG. 1 have larger leakage current, but parasitic capacitance of a discharge tube is very small, and the piezoresistor RV2 and the piezoresistor RV3 are separated from FG ends after the discharge tube BK1 is restored to a cut-off state.

The surge protection circuit provided by the embodiment of the utility model can protect the switching power supply when the switching power supply bears surge voltage, avoid the interference of the switching power supply to other equipment when the switching power supply bears interference, enhance the anti-risk capability of the power automation device under the condition that the surge voltage occurs, and prevent the leakage current from flowing back to the ground to cause electric shock hidden trouble to field operators. The surge protection circuit provided by the embodiment of the utility model has the advantages of simple structure, reduced use quantity of components, low cost, stability and reliability, and suitability for popularization and application, and the related components are universal components.

Example two

In this embodiment, the surge protection circuit described in the first embodiment is used as the switching power supply.

The surge protection circuit provided by the embodiment of the utility model can protect the switching power supply when bearing surge voltage, avoid the interference of the switching power supply to other equipment when bearing interference, enhance the risk resistance of the power automation device under the condition of the surge voltage, and prevent the leakage current from flowing back to the ground to cause electric shock hidden trouble to field operators.

Note that the above is only a preferred embodiment of the present utility model and the technical principle applied. The present utility model is not limited to the specific embodiments described herein, but is capable of numerous modifications, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the utility model. Therefore, while the utility model has been described in connection with the above embodiments, the utility model is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the utility model, which is set forth in the following claims.

Claims (3)

1. A surge protection circuit is characterized by comprising a differential mode surge suppression circuit and a common mode surge suppression circuit; the differential mode surge suppression circuit comprises a fuse tube FU1, a piezoresistor RV1, a thermistor RT1, a capacitor C2 and an inductor LB1; the common-mode surge suppression circuit comprises a piezoresistor RV2, a piezoresistor RV3, a capacitor C3 and a capacitor C4; one end of the fuse FU1 is connected with a mains supply wire end, the other end of the fuse is connected with one end of the piezoresistor RV1 and one end of the thermistor RT1, the other end of the piezoresistor RV1 is connected with a mains supply zero wire end, one end of the capacitor C2, one end of the piezoresistor RV3 and a first wiring end of the inductor LB1, the other end of the piezoresistor RV3 is connected with a second wiring end of the inductor LB1, one end of the capacitor C1 and a first alternating current pin of the rectifier bridge BR1, the other end of the thermistor RT1 is connected with the other end of the capacitor C2, one end of the piezoresistor RV2 and a third wiring end of the inductor LB1, the other end of the piezoresistor RV2 is connected with a fourth wiring end of the inductor LB1, the other end of the capacitor C1, one end of the capacitor C4 and a second alternating current pin of the rectifier bridge BR1, and the other end of the capacitor C3 is connected with the other end of the capacitor C4 and then connected with an FG end.

2. The surge protection circuit of claim 1 wherein said capacitor C1 and said capacitor C2 each employ a safety capacitor.

3. A switching power supply employing the surge protection circuit of any one of claims 1 to 2.

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