CN117060363A

CN117060363A - Low-cost lightning-proof surge circuit

Info

Publication number: CN117060363A
Application number: CN202311303488.0A
Authority: CN
Inventors: 林双龙
Original assignee: Guangdong Dongling Power Technology Co ltd
Current assignee: Guangdong Dongling Power Technology Co ltd
Priority date: 2023-10-10
Filing date: 2023-10-10
Publication date: 2023-11-14

Abstract

The low-cost lightning protection surge circuit is characterized in that a thermistor NTC1 is connected to an N phase, a piezoresistor RV2 is arranged between an L phase and an N phase, the piezoresistor RV2 is connected with a common mode LF2, a capacitor CX1 is further arranged between two ends of the common mode LF2, one end of the capacitor CX1 is connected with a PE end through an inductor L5 and a capacitor CY5, the other end of the capacitor CX1 is connected with the PE end through an inductor L4 and a capacitor CY4, the capacitor CX1 is connected with the common mode LF1, the output end of the capacitor CX1 is provided with the piezoresistor RV1, the rectifier bridge BD1 is further connected with a grounding end of the rectifier bridge BD1, and the grounding end of the rectifier bridge BD1 is connected with the PE end through a capacitor CY 3; when the PCB is seen, the discharging saw teeth are arranged between the two groups of inductors of the common mode inductor, the distance between the discharging saw teeth is designed to be 0.5-0.75mm, and the conventional lightning surge prevention effect can be achieved by only using one safety rule Y1 capacitor and saw tooth discharging design skill, so that the lightning surge common mode 6 KV/differential mode 8KV input can be met, and the power supply can be effectively protected from being damaged.

Description

Low-cost lightning-proof surge circuit

Technical Field

The application relates to the field of LED illumination, in particular to a low-cost lightning-proof surge circuit.

Background

The outdoor LED lighting power supply is widely applied to a plurality of demonstration projects at home and abroad, and based on the harsh use environment, the outdoor LED lighting power supply is designed to mainly evaluate problems caused by factors such as water resistance, high temperature, lightning stroke and the like. Lightning strikes are a natural phenomenon, particularly in rainy seasons. The damage and loss caused by the lightning stroke are counted in billions of yuan each year, and the lightning stroke is divided into a direct lightning stroke and an indirect lightning stroke, wherein the indirect lightning stroke mainly comprises a conductive lightning stroke and an inductive lightning stroke. Because the energy impact caused by direct lightning is very large, the damage is very strong, and the power supply is not bearable in general. The application is only applicable to indirect lightning, including both conductive and inductive lightning types.

A traditional lightning protection typical circuit in a switching power supply is formed by connecting two piezoresistors in parallel with L and N respectively and then connecting a discharge tube in series to a protection ground (PE). Although the circuit has good lightning protection effect of the power supply, the voltage-withstanding value of the piezoresistor is generally hundreds of volts because the circuit is connected between the L/N and the Protective Earth (PE) in parallel, and a discharge tube with the voltage-withstanding value of more than 1.5KV is needed to meet the safety requirement (1.75 KVAC/5 mA) of the insulation strength between the L/N and the PE. But this element is costly. Therefore, the cost performance of the lightning protection circuit formed by two voltage-sensitive discharge tubes is greatly reduced in the power supply design with higher cost requirement.

Disclosure of Invention

In order to solve the problems, the technical scheme provides a low-cost lightning-proof surge circuit.

In order to achieve the above purpose, the technical scheme is as follows:

the utility model provides a low-cost lightning protection surge circuit, includes L looks and N looks of input, N looks is connected with thermistor NTC1, be connected with piezo-resistor RV2 between L looks and the N looks, be connected with the input of common mode LF2 at piezo-resistor RV 2's both ends, be equipped with resistance R29, resistance R30 and resistance R31 in proper order between the output both ends of common mode LF2, still be equipped with electric capacity CX1 between the output both ends of common mode LF2, electric capacity CX1 one end connects the PE end through inductance L5 and electric capacity CY5, and the other end connects the PE end through inductance L4 and electric capacity CY4, electric capacity CX 1's both ends are connected with the input of common mode LF1, are equipped with piezo-resistor RV1 between its output both ends, still are connected with rectifier bridge BD1, rectifier bridge BD 1's ground connection passes through electric capacity CY3 and connects the PE end;

and when seen on the PCB, discharge saw teeth are arranged between the two groups of inductors of the common-mode inductor, and the distance between the discharge saw teeth is designed to be 0.5-0.75 mm.

In some embodiments, the discharge saw teeth are provided with tips, and the tips on both sides are disposed opposite to each other.

In some embodiments, the L phase is also connected with a fuse F1.

The application has the beneficial effects that:

the circuit of the application can basically achieve the effect of lightning stroke and surge prevention of the conventional combined circuit of two piezoresistors and a discharge tube by using the PCLYOUT skill of one safety rule Y1 capacitor and sawtooth discharge, has higher cost performance when being used in occasions with higher cost requirements and not very high lightning stroke and surge common mode 6 KV/differential mode 8KV input, and can effectively protect the power supply from being damaged.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below.

FIG. 1 is a prior art schematic;

FIG. 2 is a schematic circuit diagram of an embodiment of the present application;

fig. 3 is a schematic diagram of pclyout according to an embodiment of the present application.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects solved by the application more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

Referring to fig. 1-3, a low-cost lightning-protection surge circuit comprises an L phase and an N phase at an input end, wherein the N phase is connected with a thermistor NTC1, a piezoresistor RV2 is connected between the L phase and the N phase, two ends of the piezoresistor RV2 are connected with an input end of a common mode LF2, a resistor R29, a resistor R30 and a resistor R31 are sequentially arranged between two ends of an output end of the common mode LF2, a capacitor CX1 is further arranged between two ends of the output end of the common mode LF2, one end of the capacitor CX1 is connected with a PE end through an inductor L5 and a capacitor CY5, the other end of the capacitor CX1 is connected with the PE end through an inductor L4 and a capacitor CY4, two ends of the capacitor CX1 are connected with an input end of the common mode LF1, a piezoresistor RV1 is arranged between two ends of an output end of the capacitor CX1, and a rectifier bridge BD1 is further connected with a ground end of the rectifier bridge BD1 is connected with the PE end through a capacitor CY 3;

In this embodiment, the discharge saw teeth are provided with tips, and the tips on both sides are disposed opposite to each other.

In this embodiment, the L phase is also connected with a fuse F1.

In the conventional circuit of fig. 1, when the common mode lightning surge is input, energy is blocked and weakened a little by the thermistor NTC1, and then is grounded (PE) by the discharge tube M1 after passing through the piezoresistor RV4 or RV5, so as to form a loop, and the leakage is performed.

Referring to fig. 2 and 3, when energy is blocked and weakened by a thermistor NTC1 when a common mode lightning surge is input, and then passes through a common mode LF2, the energy is relaxed because the current in the inductor cannot be suddenly changed, but the energy is damaged if the induced electromotive force is not limited and neutralized because a higher induced electromotive force is generated, at this time, a discharging saw tooth is added between two groups of inductors of the common mode inductor, the distance between the saw teeth is designed to be between 0.5 and 0.75mm, and when the induced electromotive force of the inductor is higher than 500 to 750V, the tip arc discharge is performed between the two saw teeth to discharge the energy, so that the energy of the lightning surge is further weakened; then, since the safety Y1 capacitor CY4/CY5 is connected in parallel between the L/N and the ground to form a loop, a part of energy can be discharged through the CY4/CY 5. The rest energy of the lightning surge is also weakened when passing through the common mode LF1, and finally after passing through the rectifier bridge, the rest energy which is not discharged or consumed by the lightning surge is conducted from the anode of the rectifier bridge to the cathode of the rectifier bridge due to the large filter capacitance after rectification, and although the rest energy is weakened and consumed to a certain extent after passing through the front thermosensitive, common mode and Y capacitance, the rest energy also needs to be returned to the PE for collecting and discharging. The circuit of the application is provided with the safety rule Y1 capacitor between the negative electrode of the rectifier bridge and PE ground, and the lightning surge is instant rapid pulse and is equivalent to alternating current, so the Y1 capacitor can effectively form a discharge loop for the rectifier bridge. The safety Y1 capacitor can withstand a voltage 10 times higher than the nominal withstand voltage (about 4000V), and is therefore absolutely safe. Residual voltage of lightning surge after the discharging of the circuit is insufficient to damage a power supply.

When the differential mode lightning surge is input, after energy is weakened by the thermistor NTC1, a relief loop is formed between the L line and the N line through the first-stage piezoresistor RV2 for collecting and releasing, and the rest energy is relieved again between the L line and the N line through the second-stage pressure-sensitive resistor RV1 after the energy is weakened by the common modes LF2 and LF 1. The same residual voltage of the lightning surge after the discharge of the circuit of the application is insufficient to damage our power supply.

A large number of actual measurement and experiments prove that the circuit can bear the lightning surge input of common mode 6KV and differential mode 8 KV.

The circuit of the application is simple and effective, and the fine and ingenious structure ensures that the circuit of the application has low cost, and the Y capacitor to the ground is introduced at the cathode of the bridge pile, so that the safety of the power supply when lightning surge occurs is skillfully ensured, and meanwhile, the performance of filtering the interference noise of the power supply is good, so that the integral EMI/EMC characteristic of the power supply is much better.

The foregoing description of the preferred embodiments of the present application is not intended to limit the scope of the application, but rather is presented in the claims.

Claims

1. The utility model provides a low-cost lightning protection surge circuit, its characterized in that includes L phase and the N phase of input, N phase is connected with thermistor NTC1, be connected with piezo-resistor RV2 between L phase and the N phase, piezo-resistor RV 2's both ends are connected with the input of common mode LF2, be equipped with resistance R29, resistance R30 and resistance R31 in proper order between the output both ends of common mode LF2, still be equipped with electric capacity CX1 between the output both ends of common mode LF2, electric capacity CX1 connects the PE end through inductance L5 and electric capacity CY5, and the other end connects the PE end through inductance L4 and electric capacity CY4, electric capacity CX 1's both ends are connected with the input of common mode LF1, are equipped with piezo-resistor RV1 between its output both ends, still be connected with rectifier bridge BD1, rectifier bridge BD 1's ground connection PE end through electric capacity CY 3;

2. A low cost lightning and surge protection circuit according to claim 1 and wherein: the discharging saw teeth are provided with pointed ends, and the pointed ends on two sides are oppositely arranged.

3. A low cost lightning and surge protection circuit according to claim 1 and wherein: the L phase is also connected with a fuse F1.