Self-recovery AC input overvoltage protection circuit

Abstract

A self-recovery alternating current input overvoltage protection circuit comprises a live wire, a zero wire, a resistance-capacitance step-down circuit, a rectification circuit, a filter circuit and an output control circuit, the left end of the live wire is a live wire input end, the right end of the live wire is a live wire output end, and the left side of the lower portion of the live wire is connected with the resistance-capacitance step-down circuit. The lower portion of the resistance-capacitance step-down circuit is connected with the rectification circuit, the lower portion of the rectification circuit is connected with the filter circuit, the lower portion of the filter circuit is connected with the zero line, the right side of the lower portion of the live wire is connected with the output control circuit, the lower portion of the output control circuit is connected with the zero line, the left end of the zero line is a zero line input end, and the right end of the zero line is a zero line output end. According to the circuit design of the utility model, current input is subjected to resistance-capacitance voltage reduction, rectification and filtering to supply power to the normally-closed relay, the voltage-regulator tube DZ1 controls the normally-closed relay, and the voltage-regulator tube DZ2 protects the coil of the normally-closed relay, so that the design is simple in structure and low in cost, and overvoltage protection of a line can be realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric power supply, and in particular relates to a self-recovering AC input overvoltage protection circuit. Background Art

[0002] There are currently two main types of overvoltage protection. One is to protect through the power chip. When the voltage exceeds the overvoltage value of the power supply, the power supply stops working, the back end of the power supply stops outputting, and the various circuits stop working. This method can only protect the back end of the power supply, but cannot protect the power chip itself and the filtering and rectifying devices at its front end. It is only suitable for slight overvoltages. When the input is severely overvoltage, the filtering and rectifying devices may be damaged. The other is to add an overvoltage protector to the power input end. When overvoltage occurs, the overvoltage protector cuts off the power input to achieve protection. However, the overvoltage protector is large in size and high in cost. At present, the maximum protection voltage of most overvoltage protectors can only reach 450Vac, which cannot meet the board-level application scenarios with high requirements on size and cost, and the maximum protection voltage is greater than 450Vac.

[0003] Based on this, in order to realize a small-volume, low-cost overvoltage protector, this design proposes a self-recovering AC input overvoltage protection circuit. Utility Model Content

[0004] The utility model aims to provide a self-recovering AC input overvoltage protection circuit.

[0005] A self-recovering AC input overvoltage protection circuit comprises: a live wire, a neutral wire, a RC step-down circuit, a rectifier circuit, a filter circuit, and an output control circuit, wherein the left end of the live wire is a live wire input end, the right end of the live wire is a live wire output end, the left side of the lower part of the live wire is connected to a RC step-down circuit, the lower part of the RC step-down circuit is connected to a rectifier circuit, the lower part of the rectifier circuit is connected to a filter circuit, the lower part of the filter circuit is connected to a neutral wire, the right side of the lower part of the live wire is connected to an output control circuit, the lower part of the output control circuit is connected to a neutral wire, the left end of the neutral wire is a neutral wire input end, and the right end of the neutral wire is a neutral wire output end.

[0006] Preferably, the RC step-down circuit comprises: a resistor R1 and a capacitor C2, the upper ends of the resistor R1 and the capacitor C2 are both connected to the live wire, and the lower ends of the resistor R1 and the capacitor C2 are connected and connected to the rectifier circuit.

[0007] Preferably, the rectifier circuit includes: a diode D1 and a diode D2, the diode D1 and the diode D2 are installed in opposite directions, pin No. 2 of the diode D2 is connected to the RC step-down circuit, pin No. 1 of the diode D2 is connected to the neutral line, pin No. 1 of the diode D1 is connected to the RC step-down circuit, pin No. 2 of the diode D1 is connected to the upper part of the filter circuit, the right side of pin No. 2 of the diode D1 is also connected to the output control circuit, and the lower part of the filter circuit is connected to the neutral line.

[0008] Preferably, the output control circuit includes: a normally closed relay K1, a voltage regulator DZ1 and a voltage regulator DZ2, pin No. 4 on the upper part of the normally closed relay K1 is connected to the live wire input end, pin No. 3 on the upper part of the normally closed relay K1 is connected to the live wire output end, pin No. 5 of the normally closed relay K1 is to be connected, pin No. 2 of the normally closed relay K1 is connected to pin No. 2 of the diode D1 in the rectifier circuit, pin No. 2 of the normally closed relay K1 is also connected to pin No. 2 of the voltage regulator DZ2, pin No. 1 of the voltage regulator DZ2 is connected to pin No. 1 of the normally closed relay K1, pin No. 1 of the voltage regulator DZ2 is also connected to pin No. 2 of the voltage regulator DZ1, and pin No. 1 of the voltage regulator DZ1 is connected to the neutral line.

[0009] The beneficial effects of the above scheme are:

[0010] 1. The circuit design of the utility model supplies power to the normally closed relay through current input, resistance-capacitance voltage reduction, rectification and filtering. The voltage regulator DZ1 controls the normally closed relay, and the voltage regulator DZ2 protects the normally closed relay coil. This design has a simple structure, low cost and can achieve overvoltage protection for the line. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the circuit structure principle of the utility model;

[0012] In the figure: 6, RC step-down circuit; 7, rectification; 8, filtering; 9, diabolo output; 10, live wire; 11, neutral wire. DETAILED DESCRIPTION

[0013] The present invention is further explained in detail below in conjunction with the accompanying drawings of the specification, but the protection scope of the present invention is not limited thereto.

[0014] according to Figure 1As shown, a self-recovering AC input overvoltage protection circuit includes: a live wire 10, a neutral wire 11, a RC step-down circuit 6, a rectifier circuit 7, a filter circuit 8, and an output control circuit 9, wherein the left end of the live wire 10 is the live wire 10 input end, the right end of the live wire 10 is the live wire 10 output end, the left side of the lower part of the live wire 10 is connected with the RC step-down circuit 6, the lower part of the RC step-down circuit 6 is connected to the rectifier circuit 7, the lower part of the rectifier circuit 7 is connected to the filter circuit 8, the lower part of the filter circuit 8 is connected to the neutral wire 11, the right side of the lower part of the live wire 10 is connected to the output control circuit 9, the lower part of the output control circuit 9 is connected to the neutral wire 11, the left end of the neutral wire 11 is the neutral wire 11 input end, and the right end of the neutral wire 11 is the neutral wire 11 output end.

[0015] Specifically, the RC step-down circuit 6 includes: a resistor R1 and a capacitor C2 , the upper ends of the resistor R1 and the capacitor C2 are both connected to the live wire 10 , and the lower ends of the resistor R1 and the capacitor C2 are connected to the rectifier circuit 7 .

[0016] Specifically, the rectifier circuit 7 includes: a diode D1 and a diode D2, the diode D1 and the diode D2 are installed in opposite directions, pin No. 2 of the diode D2 is connected to the RC step-down circuit 6, pin No. 1 of the diode D2 is connected to the neutral line 11, pin No. 1 of the diode D1 is connected to the RC step-down circuit 6, pin No. 2 of the diode D1 is connected to the upper part of the filter circuit 8, the right side of pin No. 2 of the diode D1 is also connected to the output control circuit 9, and the lower part of the filter circuit 8 is connected to the neutral line 11.

[0017] Specifically, the output control circuit 9 includes: a normally closed relay K1, a voltage regulator tube DZ1 and a voltage regulator tube DZ2, wherein the No. 4 pin on the upper part of the normally closed relay K1 is connected to the input end of the live wire 10, the No. 3 pin on the upper part of the normally closed relay K1 is connected to the output end of the live wire 10, the No. 5 pin of the normally closed relay K1 is to be connected, the No. 2 pin of the normally closed relay K1 is connected to the No. 2 pin of the diode D1 in the rectifier circuit 7, the No. 2 pin of the normally closed relay K1 is also connected to the No. 2 pin of the voltage regulator tube DZ2, the No. 1 pin of the voltage regulator tube DZ2 is connected to the No. 1 pin of the normally closed relay K1, the No. 1 pin of the voltage regulator tube DZ2 is also connected to the No. 2 pin of the voltage regulator tube DZ1, and the No. 1 pin of the voltage regulator tube DZ1 is connected to the neutral line;

[0018] During operation, the voltage input supplies power to the normally closed relay through the RC step-down circuit 6. When the input voltage is normal, the voltage after the RC step-down circuit is insufficient to drive the normally closed relay to operate. When the voltage is over-voltage, the voltage across the normally closed relay coil will reach the operating voltage of the relay, and the normally closed relay will operate to disconnect the output.

[0019] If the operating voltage U is determined by the input voltage frequency F, the capacitance C of C2, the forward voltage drop Vf of the diode D1, the operating voltage Ur of the relay, the resistance Rr of the relay coil, and the voltage Uz of the voltage regulator, the relationship is U=[Ur / (2πF·C·Rr)+Vf+Ur+Uz] / √2;

[0020] That is: when the input voltage Uin is less than the action voltage U, the relay does not act, and the input L-IN and the output L-OUT are directly connected. When the input voltage Uin≥U, the relay acts to disconnect the output, thereby achieving overvoltage protection.

[0021] R1, C2, and the primary and secondary withstand voltage of the relay should be selected according to the actual maximum overvoltage protection value. For example, if the maximum overvoltage protection is 500Vac, it is necessary to select more than 500Vac. The voltage stabilization value of DZ2 is selected according to the maximum rated voltage of the relay coil to achieve protection of the relay coil.

Claims

1. A self-recovering AC input overvoltage protection circuit, comprising: A live wire (10), a neutral wire (11), a resistor-capacitor voltage-drop circuit (6), a rectifier circuit (7), a filter circuit (8), and an output control circuit (9), characterized in that the left end of the live wire (10) is the live wire (10) input end, the right end of the live wire (10) is the live wire (10) output end, the left side of the lower part of the live wire (10) is connected to the resistor-capacitor voltage-drop circuit (6), the lower part of the resistor-capacitor voltage-drop circuit (6) is connected to the rectifier circuit (7), the lower part of the rectifier circuit (7) is connected to the filter circuit (8), the lower part of the filter circuit (8) is connected to the neutral wire (11), the right side of the lower part of the live wire (10) is connected to the output control circuit (9), the lower part of the output control circuit (9) is connected to the neutral wire (11), the left end of the neutral wire (11) is the neutral wire (11) input end, and the right end of the neutral wire (11) is the neutral wire (11) output end.

2. A self-recovering AC input overvoltage protection circuit as claimed in claim 1, characterized in that: The RC step-down circuit (6) comprises: a resistor R1 and a capacitor C2, the upper ends of the resistor R1 and the capacitor C2 are both connected to a live wire (10), and the lower ends of the resistor R1 and the capacitor C2 are connected and connected to a rectifier circuit (7).

3. A self-recovering AC input overvoltage protection circuit as claimed in claim 1, characterized in that: The rectifier circuit (7) comprises: a diode D1 and a diode D2, wherein the diode D1 and the diode D2 are installed in opposite directions, the No. 2 pin of the diode D2 is connected to the RC step-down circuit (6), the No. 1 pin of the diode D2 is connected to the neutral line (11), the No. 1 pin of the diode D1 is connected to the RC step-down circuit (6), the No. 2 pin of the diode D1 is connected to the upper part of the filter circuit (8), the right side of the No. 2 pin of the diode D1 is also connected to the output control circuit (9), and the lower part of the filter circuit (8) is connected to the neutral line (11).

4. A self-recovering AC input overvoltage protection circuit as claimed in claim 1, characterized in that: The output control circuit (9) comprises: a normally closed relay K1, a voltage regulator tube DZ1 and a voltage regulator tube DZ2, wherein pin No. 4 on the upper portion of the normally closed relay K1 is connected to the input end of the live wire (10), pin No. 3 on the upper portion of the normally closed relay K1 is connected to the output end of the live wire (10), pin No. 5 of the normally closed relay K1 is to be connected, pin No. 2 of the normally closed relay K1 is connected to pin No. 2 of the diode D1 in the rectifier circuit (7), pin No. 2 of the normally closed relay K1 is also connected to pin No. 2 of the voltage regulator tube DZ2, pin No. 1 of the voltage regulator tube DZ2 is connected to pin No. 1 of the normally closed relay K1, pin No. 1 of the voltage regulator tube DZ2 is also connected to pin No. 2 of the voltage regulator tube DZ1, and pin No. 1 of the voltage regulator tube DZ1 is connected to the neutral line.

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