A surge protection circuit

Abstract

The utility model discloses a kind of anti-surge circuit in the technical field of power supply protection, including conducting circuit, conducting circuit is connected input end acquisition circuit and output end acquisition circuit respectively, input end acquisition circuit is connected with current limiting circuit.The circuit is connected on the positive and negative pole of power supply, the output voltage of circuit is collected by output end acquisition circuit, and when surge current appears, conducting circuit is excited to conduct, so that input end acquisition circuit sends power supply voltage to current limiting circuit, let the current in circuit slowly increase, so as to effectively suppress surge current, protect power safety, and not be influenced by environmental temperature.

Description

Technical Field

[0001] This utility model relates to a surge protection circuit in the field of power supply protection technology. Background Technology

[0002] Capacitors act as filters in power supplies, but at the moment of power-on, the instantaneous charging of the capacitor can create inrush current. At the instant the power is switched on, the capacitor charges rapidly, which is microscopically equivalent to a momentary short circuit, generating a spike current. The actual transient current generated can be several times or even tens of times the rated current, damaging the power supply system and, in severe cases, causing irreversible damage to equipment. Current technology uses NTC surge protection circuits: negative temperature coefficient thermistors, whose resistance decreases as temperature increases. The NTC is directly connected in series with a large capacitor. During power-on, the resistance is high, charging is slow, and the resistance decreases after power-on, reducing losses. However, a problem exists: the performance in limiting the surge current is affected by ambient temperature. At high ambient temperatures, the NTC fails to effectively limit the surge current. Utility Model Content

[0003] The purpose of this invention is to provide a surge protection circuit that can effectively suppress surge current generated at the moment of power-on and is unaffected by ambient temperature.

[0004] To achieve the above objectives, this utility model provides a surge protection circuit, including a conduction circuit, which is connected to an input acquisition circuit and an output acquisition circuit respectively, and the input acquisition circuit is connected to a current suppression circuit.

[0005] Compared with the prior art, the beneficial effect of this utility model is that the circuit is connected to the positive and negative terminals of the power supply, the output voltage of the circuit is collected by the output terminal acquisition circuit, and when a surge current occurs, the conduction circuit is activated, so that the input terminal acquisition circuit sends the power supply voltage to the current suppression circuit, allowing the current in the circuit to increase slowly, thereby effectively suppressing the surge current, protecting electrical safety, and is not affected by the ambient temperature.

[0006] As a further improvement of this utility model, the conduction circuit includes a thyristor VT1. The anode and control electrode of the thyristor VT1 are connected to the output acquisition circuit. The cathode of the thyristor VT1 is connected to pin 2 of the optocoupler U1. Pin 1 of the optocoupler U1 is connected to the output acquisition circuit through resistor R3. Pin 3 of the optocoupler U1 is connected to the positive terminal of the power supply. Pin 4 of the optocoupler U1 is connected to the input acquisition circuit.

[0007] When a surge current occurs, the circuit's output voltage increases, causing the thyristor VT1 to conduct, which in turn turns on the optocoupler. The power supply voltage is then acquired by the input acquisition circuit and sent to the current suppression circuit, which in turn turns on the current suppression circuit to suppress the surge current.

[0008] As a further improvement of this utility model, the output acquisition circuit includes resistors R4 and R5. One end of resistor R4 is connected to pin 1 of optocoupler U1 via resistor R3. The other end of resistor R4 is connected to one end of resistor R5 and the control electrode of thyristor VT1, and the other end of resistor R5 is connected to the anode of thyristor VT1.

[0009] In this way, the voltage divider signal at the output terminal is collected through resistors R1 and R2 and then sent to thyristor VT1. When there is a surge current, the voltage divider signal at the output terminal continuously increases until thyristor VT1 is turned on.

[0010] As a further improvement of this utility model, the input acquisition circuit includes resistors R1 and R2. One end of resistor R1 is connected to pin 4 of optocoupler U1, and the other end of resistor R1 is connected to one end of resistor R2 and the current suppression circuit. The other end of resistor R2 is connected to the current suppression circuit and the negative terminal of the power supply.

[0011] In this way, the voltage of the power supply is collected by resistors R1 and R2 to form a voltage divider signal, which is then transmitted to the current suppression circuit via an optocoupler, thereby turning on the current suppression circuit.

[0012] As a further improvement of this utility model, the current suppression circuit includes MOSFETs Q1 and Q2. A capacitor C2 is connected in parallel between the source and gate of MOSFET Q1. The source of MOSFET Q1 is connected to the anode of Zener diode D1 and the source of MOSFET Q2. The anode of Zener diode D1 is connected to the other end of resistor R2. The cathode of Zener diode D1 is connected to one end of resistor R2 and the gate of MOSFET Q1. The gate of MOSFET Q1 is connected to the gate of MOSFET Q2. The drain of MOSFET Q1 is connected to the drain of MOSFET Q2 and the anode of thyristor VT1. Resistors R6 and R7 are connected in parallel between the source and drain of MOSFET Q2.

[0013] When the optocoupler is turned on, the positive terminal voltage of the power supply is sent to the gates of MOSFETs Q1 and Q2 via the voltage divider signal obtained from pins 3 and 4 of the optocoupler and resistors R1 and R2, thus turning them on. A capacitor C2 is connected between the gate and source of the MOSFETs. The voltage divider signal obtained from resistors R1 and R2 causes capacitor C2 to start charging, and the gate-source voltage of the MOSFETs will rise slowly, causing the current in the power supply circuit to increase slowly, thereby reducing the surge current. Attached Figure Description

[0014] Figure 1 This is the circuit diagram of the auxiliary power supply for this utility model. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings:

[0016] like Figure 1The surge protection circuit shown includes a conduction circuit, which is connected to both an input acquisition circuit and an output acquisition circuit. The input acquisition circuit is connected to a current suppression circuit.

[0017] The conducting circuit includes thyristor VT1. The anode and control electrode of thyristor VT1 are connected to the output acquisition circuit. The cathode of thyristor VT1 is connected to pin 2 of optocoupler U1. Pin 1 of optocoupler U1 is connected to the output acquisition circuit through resistor R3. Pin 3 of optocoupler U1 is connected to the positive terminal of the power supply. Pin 4 of optocoupler U1 is connected to the input acquisition circuit.

[0018] The output acquisition circuit includes resistors R4 and R5. One end of resistor R4 is connected to pin 1 of optocoupler U1 via resistor R3. The other end of resistor R4 is connected to one end of resistor R5 and the control electrode of thyristor VT1. The other end of resistor R5 is connected to the anode of thyristor VT1.

[0019] The input acquisition circuit includes resistors R1 and R2. One end of resistor R1 is connected to pin 4 of optocoupler U1, and the other end of resistor R1 is connected to one end of resistor R2 and the current suppression circuit. The other end of resistor R2 is connected to the current suppression circuit and the negative terminal of the power supply.

[0020] The current suppression circuit includes MOSFETs Q1 and Q2. A capacitor C2 is connected in parallel between the source and gate of MOSFET Q1. The source of MOSFET Q1 is connected to the anode of Zener diode D1 and the source of MOSFET Q2. The anode of Zener diode D1 is connected to the other end of resistor R2. The cathode of Zener diode D1 is connected to one end of resistor R2 and the gate of MOSFET Q1. The gate of MOSFET Q1 is connected to the gate of MOSFET Q2. The drain of MOSFET Q1 is connected to the drain of MOSFET Q2 and the anode of thyristor VT1. Resistors R6 and R7 are connected in parallel between the source and drain of MOSFET Q2.

[0021] In this invention, during normal power supply, the current flows through resistors R6 and R6 to the output terminals VOUT+ and VOUT- of the circuit. Resistors R4 and R5 collect the voltage divider signal of the output voltage and send the voltage divider signal to thyristor VT1. The voltage is insufficient to turn on thyristor VT1, and the power supply is normal.

[0022] When a surge current occurs, the voltage across the output terminals VOUT+ and VOUT- of the circuit will continuously increase. When a certain voltage is reached, the voltage divider signal collected by resistors R4 and R5 will turn on the thyristor VT1, thereby turning on the optocoupler U1. Thus, the voltage at the input terminals VIN+ and VIN- of the circuit, i.e. the power supply voltage, is sent to the gates of MOSFETs Q1 and Q2 by the voltage divider signal collected by resistors R1 and R2 after passing through optocoupler U1, and turns them on.

[0023] Because a capacitor C2 is connected between the gate and source of the MOSFET, the voltage divider signal of resistors R2 and R1 will charge capacitor C2, causing the gate-source voltage VGS of the MOSFET to rise slowly, thereby gradually increasing the current in the circuit and effectively suppressing surge current.

[0024] This invention, by acquiring the output voltage, enables the gate-source power supply of MOSFETs Q1 and Q2 to rise slowly when a surge current occurs, allowing the current in the circuit to increase gradually, thereby effectively suppressing the surge current, protecting electrical safety, and is unaffected by ambient temperature.

[0025] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.

Claims

1. A surge protection circuit, characterized in that: It includes a conduction circuit, which is connected to both the input acquisition circuit and the output acquisition circuit. The input acquisition circuit is connected to the current suppression circuit. The conducting circuit includes thyristor VT1. The anode and control electrode of thyristor VT1 are connected to the output acquisition circuit. The cathode of thyristor VT1 is connected to pin 2 of optocoupler U1. Pin 1 of optocoupler U1 is connected to the output acquisition circuit through resistor R3. Pin 3 of optocoupler U1 is connected to the positive terminal of the power supply. Pin 4 of optocoupler U1 is connected to the input acquisition circuit. The output acquisition circuit includes resistors R4 and R5. One end of resistor R4 is connected to pin 1 of optocoupler U1 via resistor R3. The other end of resistor R4 is connected to one end of resistor R5 and the control electrode of thyristor VT1. The other end of resistor R5 is connected to the anode of thyristor VT1. The input acquisition circuit includes resistors R1 and R2. One end of resistor R1 is connected to pin 4 of optocoupler U1, and the other end of resistor R1 is connected to one end of resistor R2 and the current suppression circuit. The other end of resistor R2 is connected to the current suppression circuit and the negative terminal of the power supply.

2. The surge protection circuit according to claim 1, characterized in that: The current suppression circuit includes MOSFETs Q1 and Q2. A capacitor C2 is connected in parallel between the source and gate of MOSFET Q1. The source of MOSFET Q1 is connected to the anode of Zener diode D1 and the source of MOSFET Q2. The anode of Zener diode D1 is connected to the other end of resistor R2. The cathode of Zener diode D1 is connected to one end of resistor R2 and the gate of MOSFET Q1. The gate of MOSFET Q1 is connected to the gate of MOSFET Q2. The drain of MOSFET Q1 is connected to the drain of MOSFET Q2 and the anode of thyristor VT1. Resistors R6 and R7 are connected in parallel between the source and drain of MOSFET Q2.

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