A lightning protection circuit

Abstract

The utility model discloses a lightning -resistant circuit, including rectifier bridge BD1, the input of rectifier bridge BD1 connects the live wire L and zero line N of commercial power, and the live wire L and zero line N between being connected with pressure -sensitive resistance MOV1, and the live wire L has the fuse F1 in series, and rectifier bridge BD1 and commercial power between having common mode inductance LF1 and common mode inductance LF2 in series, and common mode inductance LF1 and common mode inductance LF2 between being connected with capacitor CX1 and thermistor NTC4. When lightning voltage enters from the live wire L and zero line N, first, after absorbing through pressure -sensitive resistance MOV1, then, through the high impedance structure that is formed by common mode inductance LF1 and common mode inductance LF2 in series, make the lightning surge current of whole circuit greatly reduce, reduced the influence of lightning to the post stage circuit.

Description

Technical Field

[0001] This utility model relates to a protection circuit device, and more particularly to a lightning protection circuit. Background Technology

[0002] With the rise of various electrical devices and the large-scale use of electricity, the switching transients and natural lightning transients at the AC input power system generate a strong interference voltage. If the upstream surge protection circuit is inadequate, it can cause damage and failure of the electrical equipment, making the surge protection circuit increasingly important. In existing circuit applications, to meet lightning protection requirements, multiple varistors are often added, increasing costs; at the same time, fuses need to be replaced with resistor fuses. However, replacing them with resistor fuses has certain drawbacks; under special abnormal conditions, resistor fuses are not easy to burn out, posing a risk of equipment burnout. Utility Model Content

[0003] In order to overcome the shortcomings of the existing technology, this utility model provides a lightning protection circuit.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A lightning protection circuit includes a rectifier bridge BD1. The input terminal of the rectifier bridge BD1 is connected to the live wire L and the neutral wire N of the mains power supply. A varistor MOV1 is connected between the live wire L and the neutral wire N. A fuse F1 is connected in series with the live wire L. A common mode inductor LF1 and a common mode inductor LF2 are connected in series between the rectifier bridge BD1 and the mains power supply. A capacitor CX1 and a thermistor NTC4 are connected between the common mode inductors LF1 and LF2.

[0006] As a further improvement of this utility model, the live wire L is connected to the first pin of the common mode inductor LF1, the neutral wire N is connected to the second pin of the common mode inductor LF1, the third pin of the common mode inductor LF1 is connected to the second pin of the common mode inductor LF2, the fourth pin of the common mode inductor LF1 is connected to the first pin of the common mode inductor LF2, and the thermistor NTC4 is connected in series between the third pin of the common mode inductor LF1 and the second pin of the common mode inductor LF2.

[0007] As a further improvement of this utility model, the second pin of the common mode inductor LF2 is connected to the negative power supply through capacitors CY3 and CY4. Specifically, the negative power supply is the ground wire.

[0008] As a further improvement of this utility model, the output terminal of the rectifier bridge BD1 is connected to the load, and an electrolytic capacitor EC1, an electrolytic capacitor EC2 and a capacitor C1 are connected in parallel between the third and fourth pins of the rectifier bridge BD1. A thermistor NTC1 is connected in series with the third pin of the rectifier bridge BD1, and a thermistor NTC2 is connected in series with the fourth pin of the rectifier bridge BD1.

[0009] As a further improvement of this utility model, the varistor MOV1 is model 10D681K.

[0010] The beneficial effects of this utility model are as follows: This utility model includes a rectifier bridge BD1. The input terminal of the rectifier bridge BD1 is connected to the live wire L and the neutral wire N of the mains power. A varistor MOV1 is connected between the live wire L and the neutral wire N. A fuse F1 is connected in series with the live wire L. Common mode inductors LF1 and LF2 are connected in series between the rectifier bridge BD1 and the mains power. A capacitor CX1 and a thermistor NTC4 are connected between the common mode inductors LF1 and LF2. When a lightning strike voltage enters from the live wire L and the neutral wire N, it is first absorbed by the varistor MOV1, and then passes through the high impedance structure formed by the common mode inductors LF1 and LF2 connected in series. This significantly reduces the lightning surge current of the entire circuit, reducing the impact of lightning strikes on subsequent circuits. Attached Figure Description

[0011] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0012] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features of the present utility model can be combined with each other.

[0014] It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this invention.

[0015] The following describes some embodiments of the present invention with reference to the accompanying drawings.

[0016] Reference Figure 1A lightning protection circuit includes a rectifier bridge BD1. The input terminal of the rectifier bridge BD1 is connected to the live wire L and the neutral wire N of the mains power supply. A varistor MOV1 is connected between the live wire L and the neutral wire N. A fuse F1 is connected in series with the live wire L. Common-mode inductors LF1 and LF2 are connected in series between the rectifier bridge BD1 and the mains power supply. A capacitor CX1 and a thermistor NTC4 are connected between the common-mode inductors LF1 and LF2. The common-mode inductors LF1 and LF2 are connected in series to form a high-impedance structure. In this embodiment, when a lightning strike voltage enters from the live wire L and the neutral wire N, it is first absorbed by the varistor MOV1, reducing the voltage to 600-800V. Then, after passing through the impedance of the common-mode inductors LF1 and LF2, the voltage is clamped to a safe voltage of 400VDC by the rectifier bridge BD1, which significantly reduces the lightning surge current of the entire circuit and reduces the impact of lightning strikes on subsequent circuits.

[0017] The varistor MOV1 used is model 10D681K. 10D681K is a commonly used varistor model. Under normal operation, voltage fluctuations generally will not exceed its varistor voltage. However, when overvoltage conditions such as lightning surges occur and the voltage exceeds 680V, ​​the resistance value of the varistor MOV1 will decrease rapidly, bypassing the excessive voltage to ground in the form of a large current, thereby protecting the components in the subsequent circuit from high voltage impact.

[0018] The live wire L is connected to pin 1 of common-mode inductor LF1, the neutral wire N is connected to pin 2 of common-mode inductor LF1, pin 3 of common-mode inductor LF1 is connected to pin 2 of common-mode inductor LF2, pin 4 of common-mode inductor LF1 is connected to pin 1 of common-mode inductor LF2, and the thermistor NTC4 is connected in series between pin 3 of common-mode inductor LF1 and pin 2 of common-mode inductor LF2. Capacitor CX1 is connected between common-mode inductors LF1 and LF2 to filter differential-mode interference signals between the live wire L and the neutral wire N. The thermistor NTC4 has a high resistance at room temperature during circuit startup, limiting surge current. As current flows, the temperature rises, and the resistance decreases, resulting in minimal impact on current during normal operation. Pin 2 of common-mode inductor LF2 is connected to the negative power supply via capacitors CY3 and CY4, specifically, the negative power supply is ground, further filtering common-mode interference signals. In this embodiment, after the common-mode inductors LF1 and LF2 are connected in series, since the number of turns and phase of the two windings are the same, the magnetic fields generated are superimposed in the same direction, causing the common-mode inductors to exhibit a high impedance state, thereby reducing the impact of lightning strikes.

[0019] As a further improvement of this utility model, the output terminal of the rectifier bridge BD1 is connected to the load. Electrolytic capacitors EC1, EC2, and C1 are connected in parallel between pins 3 and 4 of the rectifier bridge BD1. A thermistor NTC1 is connected in series with pin 3 of the rectifier bridge BD1, and a thermistor NTC2 is connected in series with pin 4 of the rectifier bridge BD1. In this embodiment, the rectifier bridge BD1 converts the input AC power to DC power. Electrolytic capacitors EC1, EC2, and C1 are used to smooth the DC voltage ripple and provide a stable DC voltage output. Thermistors NTC1 and NTC2 limit inrush current when the circuit starts up.

[0020] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A lightning protection circuit, comprising a rectifier bridge BD1, characterized in that... The input terminal of the rectifier bridge BD1 is connected to the live wire L and the neutral wire N of the mains power. A varistor MOV1 is connected between the live wire L and the neutral wire N. A fuse F1 is connected in series with the live wire L. A common mode inductor LF1 and a common mode inductor LF2 are connected in series between the rectifier bridge BD1 and the mains power. A capacitor CX1 and a thermistor NTC4 are connected between the common mode inductors LF1 and LF2.

2. The lightning protection circuit according to claim 1, characterized in that... The live wire L is connected to the first pin of the common mode inductor LF1, the neutral wire N is connected to the second pin of the common mode inductor LF1, the third pin of the common mode inductor LF1 is connected to the second pin of the common mode inductor LF2, the fourth pin of the common mode inductor LF1 is connected to the first pin of the common mode inductor LF2, and the thermistor NTC4 is connected in series between the third pin of the common mode inductor LF1 and the second pin of the common mode inductor LF2.

3. The lightning protection circuit according to claim 1, characterized in that... The second pin of the common-mode inductor LF2 is connected to the negative power supply through capacitors CY3 and CY4.

4. The lightning protection circuit according to claim 3, characterized in that... The negative power source is the ground wire.

5. The lightning protection circuit according to claim 1, characterized in that... The output terminal of the rectifier bridge BD1 is connected to the load. Electrolytic capacitors EC1, EC2 and C1 are connected in parallel between the third and fourth pins of the rectifier bridge BD1. Thermistor NTC1 is connected in series with the third pin of the rectifier bridge BD1, and thermistor NTC2 is connected in series with the fourth pin of the rectifier bridge BD1.

6. The lightning protection circuit according to claim 1, characterized in that... The varistor MOV1 used is model 10D681K.

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