An electromagnetic protection device for 24V DC power line

Abstract

The utility model discloses an electromagnetic protection device for a 24V DC power line, belonging to the technical field of electromagnetic protection, comprising a protective housing and a PCB board arranged in the protective housing; a 24V DC power line protection circuit is integrated on the PCB board; the 24V DC power line protection circuit comprises a 24V DC power supply, a first-level circuit, a second-level circuit and a third-level circuit; the 24V DC power supply is respectively connected to the first-level circuit, the second-level circuit and the third-level circuit. The utility model adopts a gas discharge tube, a transient suppression diode to limit the amplitude and cooperates with a filter circuit to complete electromagnetic protection. Through the combined use of the three, the system can be protected from overvoltages of different frequencies and energy levels, and the problem that the power supply system cannot work normally due to interference from external electromagnetic pulses is effectively solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of electromagnetic protection, and specifically relates to an electromagnetic protection device for a 24V direct current power line. Background Art

[0002] With the development of science and technology, the importance of electronic equipment and power systems has become increasingly obvious, and power supply is very important for electronic power systems. Stable and reliable power supply ensures the normal operation of equipment, prevents voltage fluctuations, and ensures the efficient and stable operation of power systems, which has a key impact on the sustainability of modern social functions. And more complex power systems also bring more complex electromagnetic environments. With the continuous development of science and technology, the popularization of electronic equipment and the widespread application of wireless communications, electromagnetic radiation has become a highly concerned issue. The increase in electromagnetic radiation may have an impact or even harm electronic and electrical systems, which has attracted attention to electromagnetic radiation protection. Electromagnetic pulses may enter the power supply system through transmission line coupling, backdoor coupling, etc., which will not only affect the normal operation of the power supply system, but also may cause electrical breakdown and melting damage to the components of the later stage of the circuit.

[0003] When designing electromagnetic radiation protection for circuits, we should not only pay attention to the radiation level of the equipment itself, but also consider factors such as the frequency, intensity and propagation path of the radiation. In electronic power systems, in order to reduce the impact of electromagnetic radiation, a common method is to use passive shielding, that is, to use electromagnetic radiation protection equipment to slow down or block the propagation of radiation. These equipment may include shielding covers, shielding boxes and shielding materials, etc., which are designed to effectively reduce the leakage of electromagnetic radiation to protect the safety of electronic equipment and end users; but the existing passive shielding effect is not good. Utility Model Content

[0004] The utility model aims to provide an electromagnetic protection device for a 24V DC power line in view of the above-mentioned deficiencies in the prior art, so as to solve the problem that the existing power supply system cannot work normally due to interference from external electromagnetic pulses.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] An electromagnetic protection device for a 24V DC power line, comprising a protective shell and a PCB board arranged in the protective shell; a 24V DC power line protection circuit is integrated on the PCB board;

[0007] The 24V DC power line protection circuit comprises a 24V DC power supply, a first-level circuit, a second-level circuit and a third-level circuit; the 24V DC power supply is connected to the first-level circuit, the second-level circuit and the third-level circuit respectively.

[0008] Furthermore, the first-stage circuit includes a first varistor, a second varistor and a gas discharge tube; the first varistor, the gas discharge tube and the second varistor are connected in series in sequence; the positive electrode of the 24V DC power supply is connected to one end of the first varistor, and the negative electrode of the 24V DC power supply is connected to one end of the second varistor.

[0009] Furthermore, the second-stage circuit is arranged between the first-stage circuit and the third-stage circuit.

[0010] Furthermore, the second-stage circuit includes a first common-mode capacitor, a common-mode inductor, and a second common-mode capacitor; the first common-mode capacitor, the common-mode inductor, and the second common-mode capacitor are arranged in parallel in sequence; and both ends of the first common-mode capacitor, both ends of the common-mode inductor, and both ends of the second common-mode capacitor are respectively connected to the positive pole of the 24V DC power supply and the negative pole of the 24V DC power supply.

[0011] Furthermore, the third stage circuit includes a first transient suppression diode, a second transient suppression diode and a third transient suppression diode; the first transient suppression diode and the second transient suppression diode are connected in series and then connected in parallel with the third transient suppression diode.

[0012] Furthermore, the positive electrode of the 24V DC power supply is connected to the first transient suppression diode, and the negative electrode of the 24V DC power supply is connected to the second transient suppression diode; and both ends of the third transient suppression diode are respectively connected to the positive electrode of the 24V DC power supply and the negative electrode of the 24V DC power supply.

[0013] Furthermore, a second common-mode capacitor is arranged in parallel between the branch where the first transient suppression diode is located and the branch where the third transient suppression diode is located.

[0014] The electromagnetic protection device for a 24V DC power line provided by the utility model has the following beneficial effects:

[0015] 1. The utility model adopts gas discharge tube, transient suppression diode limiting and cooperates with filter circuit to complete electromagnetic protection. Through the combined use of the three, the system can be protected from overvoltages of different frequencies and energy levels, and the problem of the power supply system being disturbed by external electromagnetic pulses and unable to work normally can be effectively solved.

[0016] 2. The utility model uses a second-order limiting system composed of a gas discharge tube and a transient suppression diode in the limiting part. The gas discharge tube is a device used to protect electronic equipment from damage by overvoltage or overcurrent. Its main working principle is based on the gas discharge phenomenon. When the voltage exceeds a certain threshold, the gas discharge tube will conduct electricity, thereby directing the overvoltage to the ground or other safe paths to protect the protected equipment.

[0017] 3. The transient suppression diode of the utility model is a device used to protect electronic equipment from transient overvoltage damage. Its main working principle is that when the voltage exceeds a certain threshold, the transient suppression diode will quickly turn on and guide the overvoltage to the ground or other safe paths to limit the amplitude of the overvoltage, thereby protecting the protected equipment.

[0018] 4. The transient suppression diode of the utility model has the characteristic of fast response and is suitable for processing short-term high-frequency overvoltage pulses. The gas discharge tube can absorb pulses with relatively large energy and is suitable for processing high-energy overvoltage shocks. The transient suppression diode is used in parallel with the gas discharge tube, and the starting voltage of the transient suppression diode is lower than the starting voltage of the gas discharge tube, which ensures that the overall response speed is determined by the faster transient suppression diode (when the amplitude of the input electromagnetic pulse is small, only the transient suppression diode starts); improves the withstand current of the overall transient response circuit and prolongs the service life of the transient suppression diode (when the amplitude of the input electromagnetic pulse increases, the conduction time of the gas discharge tube will be shortened, thereby quickly conducting together with the transient suppression diode, playing a role of shunting); wherein the resistor plays the role of absorbing standing waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A 24V DC power line protection circuit is provided for an electromagnetic protection device for a 24V DC power line.

[0020] Figure 2 The schematic diagram of the circuit board structure of the 24V DC power line protection circuit is shown in FIG.

[0021] Among them, 1. 24V DC power supply positive electrode; 2. 24V DC power supply negative electrode; 3. 24V DC power supply ground wire; 4. first varistor; 5. second varistor; 6. gas discharge tube; 7. first common mode capacitor; 8. second common mode capacitor; 9. common mode inductor; 10. first transient suppression diode; 11. second transient suppression diode; 12. third transient suppression diode. DETAILED DESCRIPTION

[0022] The specific implementation methods of the utility model are described below to facilitate technical personnel in this technical field to understand the utility model, but it should be clear that the utility model is not limited to the scope of the specific implementation methods. For ordinary technical personnel in this technical field, as long as various changes are within the spirit and scope of the utility model defined and determined by the attached claims, these changes are obvious, and all utility model creations using the concept of the utility model are protected.

[0023] Example 1

[0024] This embodiment provides an electromagnetic protection device for a 24V DC power line. Figure 1 and Figure 2 , which specifically include:

[0025] A protective shell and a PCB board arranged in the protective shell, wherein a 24V DC power line protection circuit is integrated on the PCB board; the protective shell is not drawn in the figure, and this embodiment does not limit the shape of the protective shell.

[0026] The 24V DC power line protection circuit includes a 24V DC power supply, a first-level circuit, a second-level circuit and a third-level circuit; the 24V DC power supply is connected to the first-level circuit, the second-level circuit and the third-level circuit respectively, and the second-level circuit is arranged between the first-level circuit and the third-level circuit.

[0027] Specifically, the first-stage circuit of this embodiment is also a first-stage discharge, which is used to clamp the overvoltage generated by the electromagnetic pulse and discharge the current passing therethrough.

[0028] The first-stage circuit includes a first varistor 4, a second varistor 5 and a gas discharge tube 6; the first varistor 4, the gas discharge tube 6 and the second varistor 5 are connected in series in sequence; the positive electrode 1 of the 24V DC power supply is connected to one end of the first varistor 4, and the negative electrode 2 of the 24V DC power supply is connected to one end of the second varistor 5.

[0029] The second stage circuit, which is also a secondary filtering circuit, is used to suppress the small common-mode and differential-mode electromagnetic interference on the power line and the wide-spectrum electromagnetic interference in the microwave frequency band.

[0030] The second-stage circuit includes a first common-mode capacitor 7, a common-mode inductor 9, and a second common-mode capacitor 8; the first common-mode capacitor 7, the common-mode inductor 9, and the second common-mode capacitor 8 are arranged in parallel in sequence; and both ends of the first common-mode capacitor 7, both ends of the common-mode inductor 9, and both ends of the second common-mode capacitor 8 are respectively connected to the positive pole 1 of the 24V DC power supply and the negative pole 2 of the 24V DC power supply.

[0031] The third-level circuit, which is also a three-level discharge circuit, is used to shunt and isolate the electromagnetic pulse and discharge the residual strong electromagnetic pulse energy again through the transient discharge tube.

[0032] The third stage circuit includes a first TVS diode 10 , a second TVS diode 11 and a third TVS diode 12 ; the first TVS diode 10 and the second TVS diode 11 are connected in series and then connected in parallel with the third TVS diode 12 .

[0033] The positive electrode 1 of the 24V DC power supply is connected to the first transient suppression diode 10, and the negative electrode 2 of the 24V DC power supply is connected to the second transient suppression diode 11; the two ends of the third transient suppression diode 12 are respectively connected to the positive electrode 1 of the 24V DC power supply and the negative electrode 2 of the 24V DC power supply.

[0034] The second common mode capacitor 8 is arranged in parallel between the branch where the first transient suppression diode 10 is located and the branch where the third transient suppression diode 12 is located.

[0035] During the specific operation, the input pulse first causes the gas discharge tube 6 to discharge. After the leakage pulse is filtered by the secondary filtering circuit, the high-frequency component in the wide-band electromagnetic pulse is suppressed. After the input pulse is protected by the protection component, the electromagnetic pulse is filtered and limited at the same time to achieve the protection of the subsequent circuit.

[0036] The circuit indicators protected by the protection circuit design of this embodiment are rated voltage 24V, withstand voltage 36V, rated current less than 40A, operating frequency is DC, and common mode inductor 9 and parallel bypass capacitor are used to construct low-pass filter response, that is, the second-stage circuit. In the discharge network design, the gas discharge tube 6 is used as the first-level discharge, and the common mode and differential mode two-way transient suppression diode array is used as the second-level clamp to ensure that after the secondary discharge, the voltage is clamped below 36V to meet the withstand voltage value. At the same time, LC filtering is used to obtain a low-pass filtering effect to ensure that the signal works normally while suppressing high-frequency pulses.

[0037] As a preferred embodiment of this embodiment, the protection component uses GDT as the first-level discharge, and the first-level GDT uses a 3RM230L-8 gas discharge tube 6 to suppress narrow-spectrum high-voltage pulses. The maximum pulse breakdown voltage of the GDT reaches 700V, which can effectively perform the first-level clamping. A transient voltage suppression diode 5.0SMDJ36CA is used as the second-level clamping, and the second-level clamping voltage is 36V.

[0038] As a preference of this embodiment, the resistance values ​​of the first varistor 4 and the second varistor 5 are preferably 121k, the first common-mode capacitor 7 and the second common-mode capacitor 8 are 3300pF, and the common-mode inductor 9 is 500uH.

[0039] Although the specific implementation of the utility model is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. An electromagnetic protection device for a 24V DC power line, characterized in that: It comprises a protective shell and a PCB board arranged in the protective shell; the PCB board is integrated with a 24V DC power line protection circuit; The 24V DC power line protection circuit comprises a 24V DC power supply, a first-level circuit, a second-level circuit and a third-level circuit; the 24V DC power supply is connected to the first-level circuit, the second-level circuit and the third-level circuit respectively.

2. The electromagnetic protection device for a 24V DC power line according to claim 1, characterized in that: The first-stage circuit includes a first varistor, a second varistor and a gas discharge tube; the first varistor, the gas discharge tube and the second varistor are connected in series in sequence; the positive electrode of the 24V DC power supply is connected to one end of the first varistor, and the negative electrode of the 24V DC power supply is connected to one end of the second varistor.

3. The electromagnetic protection device for a 24V DC power line according to claim 1, characterized in that: The second-stage circuit is arranged between the first-stage circuit and the third-stage circuit.

4. The electromagnetic protection device for a 24V DC power line according to claim 1, characterized in that: The second-stage circuit includes a first common-mode capacitor, a common-mode inductor and a second common-mode capacitor; the first common-mode capacitor, the common-mode inductor and the second common-mode capacitor are arranged in parallel in sequence; and both ends of the first common-mode capacitor, both ends of the common-mode inductor and both ends of the second common-mode capacitor are respectively connected to the positive electrode of the 24V DC power supply and the negative electrode of the 24V DC power supply.

5. The electromagnetic protection device for a 24V DC power line according to claim 4, characterized in that: The third-stage circuit includes a first transient suppression diode, a second transient suppression diode and a third transient suppression diode; the first transient suppression diode and the second transient suppression diode are connected in series and then connected in parallel with the third transient suppression diode.

6. The electromagnetic protection device for a 24V DC power line according to claim 5, characterized in that: The positive electrode of the 24V DC power supply is connected to the first transient suppression diode, and the negative electrode of the 24V DC power supply is connected to the second transient suppression diode; the two ends of the third transient suppression diode are respectively connected to the positive electrode of the 24V DC power supply and the negative electrode of the 24V DC power supply.

7. The electromagnetic protection device for a 24V DC power line according to claim 6, characterized in that: The second common mode capacitor is arranged in parallel between the branch where the first transient suppression diode is located and the branch where the third transient suppression diode is located.

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