CN204391741U - Surge protection circuit - Google Patents

Abstract

The utility model discloses a surge protection circuit, which comprises a first voltage divider circuit composed of a resistor and a capacitor, a rectifier circuit for rectifying commercial power, and a control circuit for surge protection; the control circuit A first comparator is included; the input end of the first voltage dividing circuit is connected to the output end of the rectification circuit, and the output end of the first voltage dividing circuit is connected to the first input end of the first comparator; The second input terminal of the first comparator is connected to the preset first standard power supply, and when the voltage of the commercial power is lower than the first preset value, the voltage at the output terminal of the first voltage divider circuit is lower than the preset value. The voltage of the first standard power supply, the control circuit performs surge protection control according to the state of the output level of the output terminal of the first comparator. The utility model improves the safety of power supply.

Description

surge protection circuit

technical field

The utility model relates to the technical field of home appliance control, in particular to a surge protection circuit.

Background technique

As we all know, the surge detection adopted in the prior art usually samples multiple voltage divider circuits for voltage division, and performs surge protection according to the magnitude of the voltage in each voltage divider circuit. Since the voltage of each voltage dividing circuit near the zero crossing point of the alternating current is basically the same, in order to prevent the misoperation of the surge protection at the zero crossing point, it is usually necessary to detect the zero crossing point and shield the surge protection at this time. Since there is no surge detection near the zero crossing point, the safety of power supply is low.

The above content is only used to assist in understanding the technical solution of the present utility model, and does not mean to admit that the above content is the prior art.

Utility model content

The main purpose of the utility model is to provide a surge protection circuit, aiming at improving the safety of power supply.

In order to achieve the above object, the utility model provides a surge protection circuit, which includes a first voltage divider circuit composed of a resistor and a capacitor, a rectifier circuit for rectifying the mains power, and a surge protection circuit for A control circuit for surge protection; the control circuit includes a first comparator;

The input end of the first voltage divider circuit is connected to the output end of the rectification circuit, and the output end of the first voltage divider circuit is connected to the first input end of the first comparator; the first comparator The second input terminal of the first voltage divider circuit is connected to the preset first standard power supply, and when the voltage of the commercial power is lower than the first preset value, the voltage of the output terminal of the first voltage divider circuit is lower than that of the first standard power supply voltage, the control circuit performs surge protection control according to the state of the output level of the output terminal of the first comparator.

Preferably, the first voltage divider circuit includes a first resistor, a second resistor and a first capacitor, one end of the first resistor is connected to the output end of the rectifier circuit, and the other end is connected to the ground through the second resistor. The first capacitor is connected in parallel with both ends of the second resistor; the first input terminal of the first comparator is connected to the common terminal of the first resistor and the second resistor.

Preferably, the surge protection circuit further includes a second voltage dividing circuit and a third voltage dividing circuit composed of resistors and capacitors, and the control circuit further includes a second comparator and a third comparator;

The input end of the second voltage dividing circuit is connected to the output end of the rectification circuit, the output end of the second voltage dividing circuit is connected to the first input end of the second comparator, and the second comparator The second input end of the first voltage divider circuit is connected to the output end of the first voltage divider circuit; and when there is no forward surge voltage in the mains, the voltage at the output end of the first voltage divider circuit is greater than that of the second divider The voltage at the output end of the voltage divider circuit; when there is a forward surge voltage in the mains, the voltage at the output end of the first voltage divider circuit is less than the voltage at the output end of the second voltage divider circuit;

The input end of the third voltage dividing circuit is connected to the output end of the rectification circuit, the output end of the third voltage dividing circuit is connected to the first input end of the third comparator, and the third comparator The second input end of the second input terminal is connected with the preset second standard power supply, and is used to detect the zero crossing point of the commercial power supply, and when the output terminal voltage of the third voltage dividing circuit is less than the second preset value, control the The output terminal of the second comparator outputs a preset level signal.

Preferably, the second voltage dividing circuit includes a third resistor, a fourth resistor and a second capacitor, one end of the third resistor is connected to the output end of the rectifier circuit, and the other end is connected to the ground through the fourth resistor The second capacitor is connected in parallel with both ends of the fourth resistor; the first input terminal of the second comparator is connected to the common terminal of the third resistor and the fourth resistor.

Preferably, the third voltage dividing circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor and a fourth capacitor, one end of the fifth resistor is connected to the output end of the rectification circuit, and the other end The sixth resistor and the seventh resistor are sequentially connected in series and then connected to the ground terminal; the third capacitor is connected in parallel to both ends of the fifth resistor; the fourth capacitor is connected in parallel to both ends of the seventh resistor ; The first input terminal of the third comparator is connected to the common terminal of the sixth resistor and the seventh resistor.

Preferably, the surge protection circuit further includes a fourth voltage divider circuit composed of a resistor and a capacitor, and the control circuit further includes a fourth comparator;

The input end of the fourth voltage dividing circuit is connected to the output end of the rectification circuit, the output end of the fourth voltage dividing circuit is connected to the first input end of the fourth comparator, and the fourth comparator The second input end of the second voltage dividing circuit is connected to the output end of the second voltage dividing circuit; and when there is no negative surge voltage in the mains, the voltage at the output end of the fourth voltage dividing circuit is smaller than the second dividing circuit The voltage at the output end of the voltage divider circuit; when the commercial power has a negative surge voltage, the voltage at the output end of the fourth voltage divider circuit is greater than the voltage at the output end of the second voltage divider circuit;

The third comparator is further configured to control the output terminal of the fourth comparator to output a preset level signal when the voltage at the output terminal of the third voltage dividing circuit is lower than a second preset value.

Preferably, the fourth voltage dividing circuit includes an eighth resistor, a ninth resistor and a fifth capacitor, one end of the eighth resistor is connected to the output end of the rectification circuit, and the other end is connected to the ground through the ninth resistor The fifth capacitor is connected in parallel with both ends of the ninth resistor; the first input terminal of the fourth comparator is connected to the common terminal of the eighth resistor and the ninth resistor.

Preferably, the rectifier circuit includes a first diode and a second diode, the anode of the first diode is connected to the first AC input end of the mains, and the second diode is connected to the The second AC input terminal of the commercial power is connected, and the cathode of the first diode is connected with the cathode of the second diode.

In the embodiment of the utility model, after rectifying the mains electricity by setting a rectification circuit, the first voltage divider circuit divides the voltage, and compares the divided voltage with the first standard voltage. Whether there is a forward surge voltage in the zero time period, when there is a forward surge voltage, the surge protection is performed by the control circuit. Because the utility model realizes the surge detection in the time period when the commercial power is close to zero, it prevents damage to electrical equipment due to the surge phenomenon at the zero crossing point of the commercial power, thereby improving the safety of power supply.

Description of drawings

FIG. 1 is a schematic diagram of the circuit structure of an embodiment of the surge protection circuit of the present invention.

The realization of the purpose of the utility model, functional characteristics and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The utility model provides a surge protection circuit. Referring to FIG. 1, in one embodiment, the surge protection circuit includes a first voltage divider circuit 10 composed of a resistor and a capacitor, and a rectifier circuit for rectifying mains power. 20. A control circuit 30 for performing surge protection; the control circuit 30 includes a first comparator 31;

The input end of the first voltage divider circuit 10 is connected to the output end of the rectification circuit 20, and the output end of the first voltage divider circuit 10 is connected to the first input end of the first comparator 31; The second input terminal of the first comparator 31 is connected with the preset first standard power supply, and when the voltage of the commercial power is less than the first preset value, the voltage of the output terminal of the first voltage dividing circuit 10 is less than the set value. The voltage of the first standard power supply, the control circuit 30 performs surge protection control according to the state of the output level of the output terminal of the first comparator 31 .

In this embodiment, the first input terminal of the above-mentioned first comparator 31 may be a non-inverting input terminal or an inverting input terminal, which may be specifically set according to actual needs, and is not further limited here. The above preset voltage of the first standard power supply can be set according to actual needs. In this embodiment, preferably, the voltage of the first standard power supply is +5V.

Specifically, in the working process, when the voltage of the commercial power is less than the first preset value (that is, close to the zero-crossing point), if no forward surge voltage is generated, the voltage at the output terminal of the first voltage divider circuit 10 is less than The voltage of the first standard power supply, the first comparator 31 will output the first level signal; if there is a forward surge peak voltage at this moment, then when the forward surge peak voltage arrives, the first comparator 31 The output end will output a reverse voltage to obtain a second level signal, and the control circuit 30 will perform a surge protection operation according to the second level signal.

In the embodiment of the present invention, after the rectification circuit 20 is set to rectify the mains power, the first voltage dividing circuit 10 divides the voltage, and compares the divided voltage with the first standard voltage. Whether there is a forward surge voltage during the time period when electricity is close to zero, and when there is a forward surge voltage, the control circuit 30 performs surge protection. Because the utility model realizes the surge detection in the time period when the commercial power is close to zero, it prevents damage to electrical equipment due to the surge phenomenon at the zero crossing point of the commercial power, thereby improving the safety of power supply.

Specifically, the above-mentioned first voltage divider circuit 10 includes a first resistor R1, a second resistor R2 and a first capacitor C1, one end of the first resistor R1 is connected to the output end of the rectifier circuit 20, and the other end is connected to the output end of the rectifier circuit 20 through the The second resistor R2 is connected to the ground terminal; the first capacitor C1 is connected in parallel to both ends of the second resistor R2; the first input terminal of the first comparator 31 is connected to the first resistor R1 and the second Common terminal of resistor R2.

It can be understood that the above-mentioned first resistor R1 and second resistor R2 may be formed by one resistor or multiple resistors connected in series, as long as the corresponding resistance requirements are met to realize the corresponding voltage division ratio.

Further, based on the above embodiment, in this embodiment, the above surge protection circuit also includes a second voltage divider circuit 40 and a third voltage divider circuit 50 composed of resistors and capacitors, and the control circuit 30 also includes a second comparator device 32 and the third comparator 33;

The input end of the second voltage dividing circuit 40 is connected to the output end of the rectification circuit 20, the output end of the second voltage dividing circuit 40 is connected to the first input end of the second comparator 32, and the The second input end of the second comparator 32 is connected with the output end of the first voltage dividing circuit 10; The voltage is greater than the voltage at the output terminal of the second voltage dividing circuit 40; when there is a forward surge voltage in the commercial power, the voltage at the output terminal of the first voltage dividing circuit 10 is less than that of the second voltage dividing circuit 40 the voltage at the output;

The input end of the third voltage dividing circuit 50 is connected to the output end of the rectification circuit 20, the output end of the third voltage dividing circuit 50 is connected to the first input end of the third comparator 33, and the The second input terminal of the third comparator 33 is connected with the preset second standard power supply for detecting the zero-crossing point of the commercial power, and when the output terminal voltage of the third voltage dividing circuit 33 is less than the second preset value, the output end of the second comparator 32 is controlled to output a preset level signal.

In this embodiment, by comparing the voltage of the second voltage dividing circuit 40 with the voltage of the first voltage dividing circuit 10 , the surge detection in the commercial power is realized. Further, a voltage divider circuit can also be set to realize negative surge detection.

Specifically, the above surge protection circuit also includes a fourth voltage divider circuit 60 composed of a resistor and a capacitor, and the control circuit 30 also includes a fourth comparator 34;

The input end of the fourth voltage dividing circuit 34 is connected to the output end of the rectification circuit 20, the output end of the fourth voltage dividing circuit 60 is connected to the first input end of the fourth comparator 34, and the The second input end of the fourth comparator 34 is connected with the output end of the second voltage dividing circuit 60; The voltage is less than the voltage at the output terminal of the second voltage dividing circuit 40; when there is a negative surge voltage in the mains, the voltage at the output terminal of the fourth voltage dividing circuit 60 is greater than that of the second voltage dividing circuit 40 the voltage at the output;

The third comparator 33 is further configured to control the output terminal of the fourth comparator 34 to output a preset level signal when the voltage at the output terminal of the third voltage dividing circuit 50 is lower than a second preset value.

In this embodiment, the above-mentioned third voltage dividing circuit 50 is used to realize zero-crossing detection. Specifically, when the voltage at the output terminal of the third voltage dividing circuit 50 is greater than the above-mentioned second preset value, the output terminal of the third comparator 32 outputs A level signal, when the voltage at the output terminal of the third voltage dividing circuit 50 is lower than the second preset value, the output terminal of the third comparator 32 outputs an inverted level signal. At this time, the control circuit 30 will shield the above-mentioned second comparator 32 and the fourth comparator 34 from outputting preset level signals according to the inversion level signal, thereby preventing the first voltage dividing circuit 10, the second voltage dividing circuit 40 and the fourth voltage dividing circuit from When the voltage divider circuit 60 is close to the zero point of the commercial power, the output voltages of the first voltage divider circuit 10, the second voltage divider circuit 40 and the fourth voltage divider circuit 60 are relatively close to cause the second comparator 32 and the fourth comparator 34 to output incorrectly. , thus improving the stability of the power supply.

Specifically, the above-mentioned second voltage dividing circuit 40 includes a third resistor R3, a fourth resistor R4 and a second capacitor C1, one end of the third resistor R3 is connected to the output end of the rectifier circuit 20, and the other end is connected to the output end of the rectifier circuit 20 through the The fourth resistor R4 is connected to the ground terminal; the second capacitor C2 is connected in parallel to both ends of the fourth resistor R4; the first input terminal of the second comparator 32 is connected to the third resistor R3 and the fourth Common terminal of resistor R4.

The above-mentioned third voltage dividing circuit 50 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3 and a fourth capacitor C4, one end of the fifth resistor R5 is connected to the output end of the rectifier circuit 20 The other end is connected in series with the ground terminal through the sixth resistor R6 and the seventh resistor R7; the third capacitor C3 is connected in parallel to both ends of the fifth resistor R5; the fourth capacitor C4 is connected in parallel The two ends of the seventh resistor R7; the first input end of the third comparator 33 is connected to the common end of the sixth resistor R6 and the seventh resistor R7.

The above fourth voltage divider circuit 60 includes an eighth resistor R8, a ninth resistor R9 and a fifth capacitor C5, one end of the eighth resistor R8 is connected to the output end of the rectifier circuit 20, and the other end is passed through the ninth resistor R9 is connected to the ground terminal; the fifth capacitor C5 is connected in parallel to both ends of the ninth resistor R9; the first input end of the fourth comparator 34 is connected to the eighth resistor R8 and the ninth resistor R9 public side.

It should be noted that the third resistor R3 , the fourth resistor R4 , the fifth resistor R5 , the sixth resistor R6 and the seventh resistor R7 may be one resistor, or may be composed of multiple resistors connected in series. The sizes of the first capacitor C1, the second capacitor C2 and the fifth capacitor C5 can be set according to actual needs. In this embodiment, preferably, the capacitance of the first capacitor C1 is equal to the capacitance of the fifth capacitor C5. And the capacitance of the first capacitor C1 is greater than the capacitance of the second capacitor C2.

It can be understood that, in order to reduce the demand of the first voltage dividing circuit 10, the second voltage dividing circuit 40 and the fourth voltage dividing circuit 60 on resistance voltage division, the first voltage dividing circuit 10, the second voltage dividing circuit 40 and the The input end of the fourth voltage divider circuit 60 and the output end of the rectifier circuit 20 are directly provided with a common voltage divider resistance R, after a voltage divider, the first voltage divider circuit 10, the second voltage divider circuit 40 and The fourth voltage dividing circuit 60 performs secondary voltage dividing.

It should be noted that the circuit structure of the above-mentioned rectification circuit 20 can be set according to actual needs, including the first diode D1 and the second diode D2, the anode of the first diode D1 is connected to the first diode D2 of the commercial power. An AC input terminal is connected, the second diode D2 is connected to the second AC input terminal of the mains, and the cathode of the first diode D1 is connected to the cathode of the second diode D2.

In this embodiment, the above-mentioned first AC input end can be an L line end, then the second AC input end is an N line end; the first AC input end can also be an N line end, then the second AC input end is an L line end . In this embodiment, positive surge detection and negative surge detection can be realized by using the first diode D1 and the second diode D2 to perform full-wave rectification on the commercial power.

The above are only preferred embodiments of the present utility model, and are not intended to limit the patent scope of the present utility model. Any equivalent structure or equivalent process conversion made by using the description of the utility model and the contents of the accompanying drawings, or directly or indirectly used in other related All technical fields are all included in the scope of patent protection of the utility model in the same way.

Claims (8)

1. a surge protection circuit, is characterized in that, comprise be made up of resistance and electric capacity the first bleeder circuit, for civil power is carried out rectification rectification circuit, for carrying out the control circuit of surge protection; Described control circuit comprises the first comparator;

The input of described first bleeder circuit is connected with the output of described rectification circuit, and the output of described first bleeder circuit is connected with the first input end of described first comparator; Second input of described first comparator is connected with the first preset reference power supply; and when described civil power is less than the first preset value at voltage; the voltage of the output of described first bleeder circuit is less than the voltage of described first reference power supply, and described control circuit carries out surge protection control according to the state of described first comparator output terminal output level.

2. surge protection circuit as claimed in claim 1, it is characterized in that, described first bleeder circuit comprises the first resistance, the second resistance and the first electric capacity, and one end of described first resistance is connected with the output of described rectification circuit, and the other end is connected with earth terminal by described second resistance; Described first Capacitance parallel connection is in the two ends of described second resistance; The first input end of described first comparator is connected to the common port of described first resistance and the second resistance.

3. surge protection circuit as claimed in claim 1, it is characterized in that, described surge protection circuit also comprises the second bleeder circuit and the 3rd bleeder circuit that are made up of resistance and electric capacity, and described control circuit also comprises the second comparator and the 3rd comparator;

The input of described second bleeder circuit is connected with the output of described rectification circuit, the output of described second bleeder circuit is connected with the first input end of described second comparator, and the second input of described second comparator is connected with the output of described first bleeder circuit; And when described civil power does not exist forward surge voltage, the voltage of the output of described first bleeder circuit is greater than the voltage of the output of described second bleeder circuit; When described civil power exists forward surge voltage, the voltage of the output of described first bleeder circuit is less than the voltage of the output of described second bleeder circuit;

The input of described 3rd bleeder circuit is connected with the output of described rectification circuit, the output of described 3rd bleeder circuit is connected with the first input end of described 3rd comparator, second input of described 3rd comparator is connected with the second preset reference power supply, for detecting the zero crossing of described civil power, and when the output end voltage of described 3rd bleeder circuit is less than the second preset value, the output controlling described second comparator exports preset level signal.

4. surge protection circuit as claimed in claim 3, it is characterized in that, described second bleeder circuit comprises the 3rd resistance, the 4th resistance and the second electric capacity, and one end of described 3rd resistance is connected with the output of described rectification circuit, and the other end is connected with earth terminal by described 4th resistance; Described second Capacitance parallel connection is in the two ends of described 4th resistance; The first input end of described second comparator is connected to the common port of described 3rd resistance and the 4th resistance.

5. surge protection circuit as claimed in claim 3, it is characterized in that, described 3rd bleeder circuit comprises the 5th resistance, the 6th resistance, the 7th resistance, the 3rd electric capacity and the 4th electric capacity, one end of described 5th resistance is connected with the output of described rectification circuit, and the other end is connected with earth terminal after being connected in series successively by described 6th resistance and the 7th resistance; Described 3rd Capacitance parallel connection is in the two ends of described 5th resistance; Described 4th Capacitance parallel connection is in the two ends of described 7th resistance; The first input end of described 3rd comparator is connected to the common port of described 6th resistance and the 7th resistance.

6. surge protection circuit as claimed in claim 3, it is characterized in that, described surge protection circuit also comprises the 4th bleeder circuit be made up of resistance and electric capacity, and described control circuit also comprises the 4th comparator;

The input of described 4th bleeder circuit is connected with the output of described rectification circuit, the output of described 4th bleeder circuit is connected with the first input end of described 4th comparator, and the second input of described 4th comparator is connected with the output of described second bleeder circuit; And when described civil power does not exist negative sense surge voltage, the voltage of the output of described 4th bleeder circuit is less than the voltage of the output of described second bleeder circuit; When described civil power exists negative sense surge voltage, the voltage of the output of described 4th bleeder circuit is greater than the voltage of the output of described second bleeder circuit;

Described 3rd comparator is also for when the output end voltage of described 3rd bleeder circuit is less than the second preset value, and the output controlling described 4th comparator exports preset level signal.

7. surge protection circuit as claimed in claim 6, it is characterized in that, described 4th bleeder circuit comprises the 8th resistance, the 9th resistance and the 5th electric capacity, and one end of described 8th resistance is connected with the output of described rectification circuit, and the other end is connected with earth terminal by described 9th resistance; Described 5th Capacitance parallel connection is in the two ends of described 9th resistance; The first input end of described 4th comparator is connected to the common port of described 8th resistance and the 9th resistance.

8. the surge protection circuit according to any one of claim 1 to 7; it is characterized in that; described rectification circuit comprises the first diode and the second diode; the anode of described first diode is connected with the first ac input end of described civil power; described second diode is connected with the second ac input end of described civil power, and the negative electrode of described first diode is connected with the negative electrode of described second diode.