Multi-pulse surge protection circuit and multi-pulse surge protector

Abstract

The multi-pulse surge protection circuit comprises three branches which are connected in parallel, each branch is composed of a fuse, a thermal protection type piezoresistor, a feed-through capacitor and a first litz coil, one end of the fuse is connected with a live wire, the other end of the fuse is connected with one end of the feed-through capacitor, and the other end of the feed-through capacitor is connected with the other end of the first litz coil. The other end of the feed-through capacitor is connected with one end of the thermal protection type piezoresistor, the other end of the thermal protection type piezoresistor is grounded, the first Litz coil is connected with the feed-through capacitor in parallel, and starting voltages of the thermal protection type piezoresistors on the three branches are arranged according to steps. The surge pulser solves the technical problem that an existing surge pulser adopts a switch or a hybrid design of the switch and a voltage limiting device, and matching of energy and time of the surge pulser cannot meet the requirement for suppressing lightning multi-pulse discharge pulses.

Description

Technical Field

[0001] The present invention relates to the technical field of surge protectors, and in particular to a multi-pulse surge protection circuit and a multi-pulse surge protector. Background Art

[0002] The charge polarity within a thundercloud is positive at the top and negative at the bottom, with electric field strengths reaching 50-100 MV. Typically, a discharge occurs within the thundercloud, a process known as pre-breakdown, which sets the stage for the formation of a step (downward) leader. When the electric field strength at the bottom reaches the air ionization threshold, a downward streamer begins to form, each time penetrating the air an average distance of about 50 meters. This sequence resembles a staircase, hence the name step leader, also known as a downward leader. Influenced by the electric field at the end of the downward leader, the end of the lightning rod induces a charge of opposite polarity. When the electric field strength reaches 10 kV / m, corona occurs, generating an upward corona current (streamer), known as an upward leader. The relative motion of the upward and downward leaders sets the stage for the upper and lower leaders to connect.

[0003] Lightning discharge multi-pulse waveforms such as Figure 1 As shown, when the downward leader reaches approximately 100 meters from the end of the lightning rod, it connects with the downward leader. The distance between the ends of the upward and downward leaders (the last jump) is called the strike distance, denoted by r. The magnitude of r is generally related to the lightning discharge current. Once the upper and lower leaders connect, a discharge channel is formed. Charge rushes from the earth along the discharge channel to the cloud, neutralizing the channel and the cloud charge. This process is called the first return stroke. The arrow-shaped leader, named for its arrow-like shape, moves along the lightning channel after the first lightning strike. It forms the transition between the first return stroke and the subsequent return stroke, serving as a link between the first and subsequent return strokes. The subsequent return stroke begins after the arrow-shaped leader terminates, repeating the discharge process of the first return stroke. Because each return stroke is a pulse, multiple return strokes form a series of pulses separated by time intervals. After the first return stroke establishes the lightning channel, a charge remains in the channel to maintain the channel until the discharge ends. Between the multiple return strokes of subsequent return strokes, a pulsating current with a constant direction of motion can be seen at the bottom of the pulse, which is called a continuous current. Continuous current is defined as a lower amplitude current immediately following the return stroke process and is the pulsating DC component of the lightning current in the lightning channel. Several small pulses can be seen above the continuous current, which is called the M component and is one of the three forms of charge transferred from lightning to the ground. Continuous current transfers a large amount of charge (approximately 50%), which will cause the most serious lightning damage, including thermal effects. The last return stroke refers to the last return stroke, which is characterized by a time interval of usually 300-400ms between the previous return stroke and the last return stroke, a greater amplitude than the first return stroke, and similar parameters to the first return stroke. From the first return stroke to the last lightning stroke, the lightning discharge process is complete.

[0004] Current surge pulse devices use a switch or a hybrid design of a switch and a voltage limiting device. The coordination of energy and time cannot meet the requirements of suppressing multiple lightning pulse discharge pulses. Summary of the Invention

[0005] The present invention provides a multi-pulse surge protection circuit and a multi-pulse surge protector, which are used to solve the technical problem that the existing surge pulse protectors adopt a switch or a hybrid design of a switch and a voltage limiting device, and their energy and time coordination cannot meet the requirements of suppressing lightning multi-pulse discharge pulses.

[0006] In view of this, the first aspect of the present invention provides a multi-pulse surge protection circuit, comprising three branches connected in parallel, each branch consisting of a fuse, a thermal protection type varistor, a through-hole capacitor and a first Litz coil, one end of the fuse is connected to the live wire, the other end of the fuse is connected to one end of the through-hole capacitor, the other end of the through-hole capacitor is connected to one end of the thermal protection type varistor, the other end of the thermal protection type varistor is grounded, the first Litz coil is connected in parallel with the through-hole capacitor, and the starting voltages of the thermal protection type varistors on the three branches are set in steps.

[0007] Optionally, the capacitance of the feedthrough capacitor is 4700 pF.

[0008] Optionally, the inductance of the first Litz coil is 54 mH.

[0009] Optionally, the first Litz coil is wound from 0.1 mm Litz wire.

[0010] Optionally, the first Litz coil is made by winding 3 layers of 0.1 mm Litz wire around a ferrite magnetic ring, with each layer having 100 turns.

[0011] Optionally, the starting voltages of the thermal protection varistors on the three branches are set in a ratio of 1:1.03:1.0609.

[0012] A second aspect of the present invention provides a multi-pulse surge protector, comprising the multi-pulse surge protection circuit described in any one of the first aspects, and further comprising a second Litz coil and a ferrite reinforcement layer;

[0013] The second Litz coil is laid on the ferrite reinforcement layer in a direct grounding manner, and the ferrite reinforcement layer is laid on the inner wall of the multi-pulse surge protector shell.

[0014] Optionally, the inductance of the second Litz coil is 22 mH.

[0015] Optionally, the second Litz coil is wound from 0.1 mm Litz wire.

[0016] Optionally, the second Litz coil is made of 0.1 mm Litz wire wound in 4 layers, each layer is wound with 85 turns, and the coil diameter of the second Litz coil is 50 mm.

[0017] It can be seen from the above technical solutions that the multi-pulse surge protection circuit provided by the present invention has the following advantages:

[0018] The multi-pulse surge protection circuit provided by the present invention includes three branches connected in parallel, each branch consisting of a fuse, a thermal protection type varistor, a feedthrough capacitor and a first Litz coil, one end of the fuse is connected to a live wire, the other end of the fuse is connected to one end of the feedthrough capacitor, the other end of the feedthrough capacitor is connected to one end of the thermal protection type varistor, the other end of the thermal protection type varistor is grounded, the first Litz coil is connected in parallel with the feedthrough capacitor, and the starting voltages of the thermal protection type varistors on the three branches are set in steps. By connecting a pulse fuse with large pulse current carrying capacity and small power frequency breaking capacity in parallel with a varistor, the current is evenly distributed to each branch, avoiding single-point overload, achieving graded absorption when the lightning current passes through, and effectively reducing the residual voltage generated by the lightning current. At the same time, the fuse equipped at each level can ensure that when a certain level of thermal protection varistor fails due to overload, a certain branch is accurately disconnected, and the remaining branches continue to work, ensuring that the overall protection is not interrupted. This solves the technical problem that the existing surge pulse device adopts a switch or a hybrid design of a switch and a voltage limiting device, and its energy and time coordination cannot meet the requirements of suppressing multiple lightning pulse discharge pulses. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a multi-pulse waveform diagram of lightning discharge;

[0021] Figure 2 A schematic diagram of the circuit structure of a multi-pulse surge protection circuit provided in an embodiment of the present invention;

[0022] Figure 3 The figure is a schematic structural diagram of a multi-pulse surge protector provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0024] For easier understanding, see Figure 2 The present invention provides an embodiment of a multi-pulse surge protection circuit, comprising three branches connected in parallel, each branch consisting of a fuse F, a thermal protection varistor R, a feedthrough capacitor C, and a first Litz coil L. One end of the fuse F is connected to a live wire, the other end of the fuse F is connected to one end of the feedthrough capacitor C, the other end of the feedthrough capacitor C is connected to one end of the thermal protection varistor R, the other end of the thermal protection varistor R is grounded, the first Litz coil L is connected in parallel with the feedthrough capacitor C, and the starting voltages of the thermal protection varistors R in the three branches are set in steps.

[0025] It should be noted that fuse F and thermally protected varistor R form a power-frequency short-circuit protection circuit. Fuse F is a backup protection device capable of withstanding large pulse currents and tripping when a power-frequency short-circuit current passes through it. Thermally protected varistor R also has a built-in fusible alloy. By connecting fuse F and thermally protected varistor R in series, the dual protection of disconnecting the varistor from the main circuit ensures that if the varistor R cannot withstand the excessive energy, it will be disconnected from the main circuit, protecting the entire circuit and protecting the low-voltage distribution line from the short circuit. This serves as a backup protection device and enables direct disconnection during power-frequency short-circuit testing without the need to replace the thermally protected varistor R with a copper block. Three branches of thermally protected varistors R, connected in parallel, form a stepped circuit to absorb strong electromagnetic pulse energy. Arranging the varistors in these three branches in a specific voltage step sequence allows the varistors within the surge protector to conduct step by step, effectively dissipating lightning current energy. The trigger voltages of the thermally protected varistors R in the three branches are set at a ratio of 1:1.03:1.0609. The capacitance of the feedthrough capacitors C in the three branches is 4700pF. The first Litz coil L is made of three layers of 0.1mm Litz wire wound around a ferrite ring, with 100 turns per layer, and an inductance of 54mH. The feedthrough capacitors C and the first Litz coil L form a passive resonant circuit that can directionally absorb 10kHz lightning electromagnetic waves and reduce leakage of the lightning electromagnetic field. Furthermore, the use of passive components reduces the heat generated in the shielding layer by eddy currents and hysteresis losses.

[0026] Feedthrough capacitors (C) are primarily used for high-frequency electromagnetic noise suppression, covering a range of up to 10MHz-10GHz. They utilize a three-terminal structure, offering the following advantages: They lack lead inductance. Traditional capacitor leads introduce parasitic inductance (approximately 1-10nH), leading to increased impedance at high frequencies. These capacitors, however, are directly grounded through the metal casing, eliminating lead inductance. They can operate at GHz levels (e.g., 1-10GHz) and offer lower impedance at high frequencies. The capacitance of the capacitor (typically 100pF-1μF) forms a low-impedance path with the metal casing, bypassing high-frequency noise to ground. The internal multilayer ceramic or thin-film structure optimizes the equivalent series inductance at high frequencies, ensuring broadband filtering.

[0027] The multi-pulse surge protection circuit provided by the present invention includes three branches connected in parallel. Each branch consists of a fuse F, a thermal protection type varistor R, a feedthrough capacitor C, and a first Litz coil L. One end of the fuse F is connected to a live wire, the other end of the fuse F is connected to one end of the feedthrough capacitor C, the other end of the feedthrough capacitor C is connected to one end of the thermal protection type varistor R, and the other end of the thermal protection type varistor R is grounded. The first Litz coil L is connected in parallel with the feedthrough capacitor C. The starting voltages of the thermal protection type varistor R in the three branches are set in steps. By connecting a pulse fuse F with large pulse current carrying capacity and low power frequency breaking capacity in parallel with a varistor, the current is evenly distributed to each branch, avoiding single-point overload, achieving graded absorption when the lightning current passes through, and effectively reducing the residual voltage generated by the lightning current. At the same time, the fuse F equipped at each level can ensure that when a certain level of thermal protection varistor R fails due to overload, a certain branch is accurately disconnected, and the remaining branches continue to work, ensuring uninterrupted overall protection. This solves the technical problem that the existing surge pulse device adopts a switch or a hybrid design of a switch and a voltage limiting device, and its energy and time coordination cannot meet the requirements for suppressing multiple lightning pulse discharge pulses.

[0028] For easier understanding, see Figure 2 and Figure 3The present invention provides an embodiment of a multi-pulse surge protector, which includes any multi-pulse surge protection circuit in the multi-pulse surge protection circuit embodiments provided in the present invention, and also includes a second Litz coil 200 and a ferrite reinforcement layer 300. The second Litz coil 200 is laid on the ferrite reinforcement layer 300 by direct grounding, and the ferrite reinforcement layer 300 is laid on the inner wall of the multi-pulse surge protector housing 400. Through the second Litz coil 200 and the ferrite reinforcement layer 300, the electromagnetic field in space is absorbed, and the low-frequency electromagnetic pulse energy is absorbed and discharged to the ground. The second Litz coil 200 is made of 0.1mm Litz wire wound in 4 layers, with 85 turns in each layer. The coil diameter of the second Litz coil 200 is 50mm, and the inductance of the second Litz coil 200 is 22mH. The ferrite reinforcement layer 300 is laid on the inner wall of the surge protector housing 400. The ferrite reinforcement layer 300 is a hollow rectangular parallelepiped structure as a whole, with a length of 50 mm, a width of 38 mm, a height of 40 mm, and a thickness of 2 mm.

[0029] The multi-pulse surge protector also includes a ferrite shielding layer 100, which is applied to the outer surface of the multi-pulse surge protector housing 400, and the housing 400 is reliably grounded. The ferrite shielding layer 100 is a hollow rectangular structure with a length of 71 mm, a width of 45 mm, a height of 50 mm, and a thickness of 3 mm. The double ferrite shielding of the ferrite reinforcement layer 300 and the ferrite shielding layer 100 can enhance the efficiency of absorbing the electromagnetic field of lightning current leakage. The ferrite shielding layer 100 is directly grounded, forming a shielding effect on the interior of the surge protector, absorbing the remaining leakage electromagnetic field, and minimizing the heating of the shielding layer. This avoids the defect of using only a single shielding layer, which causes most of the electromagnetic energy to generate eddy current loss and hysteresis loss in the shielding layer, generating a large amount of heat, so that an external heat dissipation device is required to assist in heat dissipation.

[0030] The terms "first" and "second" in the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, products or apparatus.

[0031] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0032] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-pulse surge protection circuit, characterized in that: It includes three branches connected in parallel, each branch consists of a fuse, a thermal protection type varistor, a through-hole capacitor and a first Litz coil, one end of the fuse is connected to the live wire, the other end of the fuse is connected to one end of the through-hole capacitor, the other end of the through-hole capacitor is connected to one end of the thermal protection type varistor, the other end of the thermal protection type varistor is grounded, the first Litz coil is connected to the through-hole capacitor in parallel, and the starting voltage of the thermal protection type varistor on the three branches is set in steps.

2. The multi-pulse surge protection circuit according to claim 1, characterized in that: The capacitance of the feedthrough capacitor is 4700pF.

3. The multi-pulse surge protection circuit according to claim 2, characterized in that: The inductance value of the first Litz coil is 54mH.

4. The multi-pulse surge protection circuit according to claim 3, characterized in that: The first litz coil is wound from 0.1 mm litz wire.

5. The multi-pulse surge protection circuit according to claim 4, characterized in that: The first Litz coil is made of 0.1mm Litz wire wound around a ferrite magnetic ring in three layers, with 100 turns in each layer.

6. The multi-pulse surge protection circuit according to claim 1, characterized in that: The starting voltages of the thermal protection varistors on the three branches are set in a ratio of 1:1.03:1.0609.

7. A multi-pulse surge protector, characterized in that: A multi-pulse surge protection circuit comprising the invention as claimed in any one of claims 1 to 6, further comprising a second Litz coil and a ferrite reinforcement layer; The second Litz coil is laid on the ferrite reinforcement layer in a direct grounding manner, and the ferrite reinforcement layer is laid on the inner wall of the multi-pulse surge protector shell.

8. The multi-pulse surge protector according to claim 7, characterized in that: The inductance of the second Litz coil is 22mH.

9. The multi-pulse surge protector according to claim 8, characterized in that: The second Litz coil is wound with 0.1 mm Litz wire.

10. The multi-pulse surge protector according to claim 9, characterized in that: The second Litz coil is made of 0.1 mm Litz wire wound in four layers, each layer having 85 turns, and the coil diameter of the second Litz coil is 50 mm.

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