CN214227810U

CN214227810U - Leakage protection circuit

Info

Publication number: CN214227810U
Application number: CN202022986983.4U
Authority: CN
Inventors: 吴洋波
Original assignee: Shenzhen H&T Intelligent Control Co Ltd
Current assignee: Shenzhen H&T Intelligent Control Co Ltd
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-09-17
Anticipated expiration: 2030-12-11

Abstract

The embodiment of the utility model discloses a leakage protection circuit, leakage detection module are arranged in detecting the leakage current in the alternating current power supply return circuit to produce leakage voltage. Under the condition that the leakage voltage is higher than the reference voltage, the output of the comparator module is a first voltage with the polarity opposite to that of the leakage voltage; in the case where the leakage voltage is lower than the reference voltage, the first voltage of the output of the comparator module is clamped to the reference voltage. The adder module carries out reverse addition operation on the leakage voltage and the first voltage, and under the condition that the leakage voltage is higher than the reference voltage, the second output end outputs a second voltage with the same polarity as the leakage voltage; the second output terminal outputs a second voltage having a polarity opposite to that of the leakage voltage when the leakage voltage is lower than the reference voltage. The driving module drives the protection switch to be disconnected according to the second voltage. The protection circuit can respond in time and disconnect the protection switch with less delay time no matter the electric leakage occurs in the positive half cycle or the negative half cycle of the alternating current power supply loop.

Description

Leakage protection circuit

Technical Field

The utility model relates to a leakage protection technical field especially relates to a leakage protection circuit.

Background

The alternating current leakage detection circuit is widely applied to a leakage detection system. The method is particularly applied to household appliances such as refrigerators, washing machines and the like. In an alternating current system, the frequency of Chinese power frequency commercial power is 50HZ, the period is 20mS, the positive half period is 10mS, and the negative half period is 10 mS.

Currently, the alternating current leakage detection circuit adopts a single leakage response mode of a positive half cycle or a negative half cycle. However, with a single leakage response, the response will be delayed by a maximum of 10 mS. For example, when a positive half-cycle leakage response is adopted and the leakage condition happens in a negative half-cycle condition, the maximum delay of 10mS occurs in the leakage response, and the delay of 10mS is important for the safety of human body electric shock.

SUMMERY OF THE UTILITY MODEL

Therefore, in order to solve the above problems, it is necessary to provide a leakage protection circuit, which aims to solve the problem that the existing leakage protection circuit adopts a positive half-cycle or negative half-cycle leakage response mode and has a long response delay time.

The utility model discloses a technical means do: the utility model provides a leakage protection circuit, use in alternating current power supply return circuit, its characterized in that includes:

the leakage detection module is used for detecting leakage current in the alternating current power supply loop and generating leakage voltage based on the leakage current;

a comparator module including a first non-inverting input terminal, a first inverting input terminal, and a first output terminal, the first non-inverting input terminal being connected to the leakage detection module, the comparator module being configured to output a first voltage having a polarity opposite to that of the leakage voltage through the first output terminal when the leakage voltage is higher than the reference voltage, and clamp the first voltage output from the first output terminal to the reference voltage and output the first voltage through the first output terminal when the leakage voltage is lower than the reference voltage;

the adder module comprises a second equidirectional input end, a second reverse input end and a second output end, the second equidirectional input end receives the reference voltage, the second reverse input end is respectively connected with the leakage detection module and the first output end, and the adder module is used for outputting a second voltage obtained by performing reverse addition operation on the leakage voltage and the first voltage through the second output end; and

and the driving module is connected with the second output end and used for driving the protection switch arranged on the alternating current power supply loop to be disconnected according to the second voltage.

Due to the adoption of the technical scheme, under the condition that the leakage voltage is higher than the reference voltage, the comparator module and the first voltage with the polarity opposite to that of the leakage voltage are subjected to reverse addition operation by the adder module, so that the second voltage with the polarity identical to that of the leakage voltage can be obtained, under the condition that the leakage voltage is lower than the reference voltage, the comparator clamps the first voltage to the reference voltage, and the adder module perform reverse addition operation on the leakage voltage and the first voltage, so that the second voltage with the polarity opposite to that of the leakage voltage can be obtained. That is, by providing the comparator module and the adder module in the earth leakage protection circuit, it is possible to cause the earth leakage voltage in the positive half cycle to be converted into the second voltage having the same polarity as the earth leakage voltage and output it, and to cause the earth leakage voltage in the negative half cycle to be converted into the second voltage having the opposite polarity to the earth leakage voltage and output it, and therefore, the second voltage corresponds to the full-wave rectified voltage of the alternating-current earth leakage voltage in the entire cycle. The protection circuit can detect the leakage voltage no matter whether the leakage occurs in the positive half cycle or the negative half cycle of the alternating current power supply loop, and can respond in time to disconnect the protection switch in the loop and reduce the delay time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Wherein:

fig. 1 is a block diagram of a leakage protection circuit according to an embodiment;

fig. 2 is a block diagram of a leakage protection circuit according to an embodiment;

fig. 3 is a schematic diagram of a leakage protection circuit provided in an embodiment.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

The terms first, second and the like in the description and in the claims, and in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be practiced otherwise than as specifically illustrated.

The embodiment of the utility model discloses electric leakage protection circuit, as shown in FIG. 1, use in AC power supply circuit 10, include: the leakage detection module 100, the comparator module 200, the adder module 300, and the driving module 500. The leakage detecting module 100 is configured to detect a leakage current in the ac power supply circuit 10 and generate a leakage voltage Ui based on the leakage current. The comparator module 200 includes a first non-inverting input terminal, a first inverting input terminal, and a first output terminal, the first non-inverting input terminal is connected to the reference voltage VREF, the first inverting input terminal is connected to the leakage detection module connection 100, and the comparator module 200 is configured to output a first voltage U1 with a polarity opposite to that of the leakage voltage Ui through the first output terminal when the leakage voltage Ui is higher than the reference voltage VREF, and clamp a first voltage U1 output by the first output terminal to the reference voltage VREF and output the first voltage U1 through the first output terminal when the leakage voltage Ui is lower than the reference voltage VREF. The adder module 300 includes a second equidirectional input end, a second inverse input end, and a second output end, the second equidirectional input end receives the reference voltage VREF, the second inverse input end is connected to the leakage detection module 100 and the first output end respectively, and the adder module 300 is configured to output, through the second output end, a second voltage U2 obtained by performing an inverse addition operation on the leakage voltage Ui and the first voltage U1. The driving module 500 is connected to the second output terminal, and is configured to drive the protection switch 600 disposed in the ac power supply circuit 10 to be turned off according to the second voltage U2. The protection switch 600 is disposed in the ac power supply circuit 10 and is configured to control on/off of the ac power supply circuit 10, when the driving module 500 receives the second voltage U2, the protection switch 600 is turned off, and when the driving module 500 does not receive the second voltage U2, the protection switch 600 is turned on.

With the leakage protection circuit of this embodiment, when the leakage voltage Ui is higher than the reference voltage, the comparator module 200 outputs the first voltage U1 with the polarity opposite to that of the leakage voltage Ui, and the adder module 300 performs the inverse addition operation on the leakage voltage Ui and the first voltage U1, so as to obtain the second voltage U2 with the polarity same as that of the leakage voltage Ui. In the case where the leakage voltage Ui is lower than the reference voltage VREF, the comparator module 200 clamps the first voltage U1 as the reference voltage VREF, and the adder module 300 performs inverse addition of the leakage voltage Ui and the first voltage U1, so that the second voltage U2 with the leakage voltage Ui having an opposite polarity can be obtained. That is, by providing the comparator module 200 and the adder module 300 in the leakage protection circuit, it is possible to cause the leakage voltage Ui in the positive half cycle to be converted into the second voltage U2 having the same polarity as the leakage voltage Ui for output, and to cause the leakage voltage Ui in the negative half cycle to be converted into the second voltage U2 having the opposite polarity to the leakage voltage Ui for output. Therefore, the second voltage U2 corresponds to a full-wave rectified voltage to the ac leakage voltage Ui throughout the cycle. The protection circuit can detect the leakage voltage Ui no matter the leakage occurs in the positive half cycle or the negative half cycle of the alternating current power supply loop 10, and can respond in time to disconnect the protection switch 600 in the loop and reduce the delay time.

In one embodiment, as shown in fig. 3, the comparator module 200 includes a first operational amplifier U31A, a first reverse resistor R1, a first feedback resistor R2, a first diode D31, and a second diode D32. The inverting input terminal of the first operational amplifier U31A is connected to the leakage detecting module 100 through a first inverting resistor R1. The same-direction input end of the first operational amplifier is connected with a reference voltage VREF. The output of the first operational amplifier U31A is connected to the anode of a first diode D31, and the output of the first operational amplifier U31A is also connected to the cathode of a second diode D32. The cathode of the first diode D31 and the anode of the second diode D32 are connected through a first feedback resistor R2; the cathode of the first diode D31 passes through the first feedback resistor R2 and the anode of the second diode and the second inverting input terminal. It is understood that the comparator block 200 is an inverse proportional operation circuit configuration. The voltage amplification factor is-R2/R1. Wherein the reference voltage is 0V.

Further, the first reverse resistor R1 and the first feedback resistor R2 have the same resistance, and the voltage amplification factor is-1. It will be appreciated that in the case of a leakage voltage in the positive half cycle, the leakage voltage Ui is greater than the reference voltage VREF and the output voltage U31Ao of the first operational amplifier U31A is less than the reference voltage VREF. At this time, the first diode D31 is turned off, the second diode D32 is turned on, the output voltage U31Ao of the first operational amplifier is the first voltage U1, and the first voltage U1 is the same as the leakage voltage Ui and in the opposite direction, that is, U1 is-Ui. In the case where the leakage voltage is in the negative half cycle, the leakage voltage Ui is less than the reference voltage VREF, and the output voltage U31Ao of the first operational amplifier U31A is greater than the reference voltage VREF. At this time, the first diode D31 is turned on, the second diode D32 is turned off, and the first voltage U1 is clamped to the reference voltage VREF, i.e., U1 is equal to VREF.

In one embodiment, the adder module 300 includes a second operational amplifier U31B, a second inverting resistor R3, a third inverting resistor R4, and a second feedback resistor R5. One end of the second reverse resistor R3 is connected to the leakage detecting module 100, and the other end of the second reverse resistor R3 is connected to the reverse input terminal of the second operational amplifier U31B. One end of the third inverting resistor R4 is connected to the first output terminal, and the other end of the third inverting resistor R4 is connected to the inverting input terminal of the second operational amplifier U31B. One end of the second feedback resistor R5 is connected to the other end of the second inverting resistor R3, and the other end of the second feedback resistor R5 is connected to the output end of the second operational amplifier U31B and connected to the driving module 500. It is understood that the adder module 300 is formed by an adding operational circuit, the output voltage U31Bo of the second operational amplifier U31B is ═ - (R5/R3 × Ui + R5/R4 × U1), and the output voltage of the second operational amplifier U31B is the second voltage U2.

Further, the resistance of the second reverse resistor R3 is the same as the resistance of the second feedback resistor R5, and the resistance of the second feedback resistor R5 is twice as large as the resistance of the third reverse resistor R4, that is, R3 ═ R5, and R5 ═ 2R 4. The second voltage U2 is the sum of the fourth voltage and the fifth voltage, the fourth voltage is the negative value of the leakage voltage Ui, i.e., -Ui, and the fifth voltage is twice the negative value of the first voltage, i.e., -2U 1.

In the case where the leakage voltage is in the positive half cycle, the first voltage is the fourth voltage, i.e., U1 ═ Ui. U2 ═ - (R5/R3 ═ Ui + R5/R4 ═ U1), where R3 ═ R5 and R5 ═ 2R4, so the second voltage is the leakage voltage, i.e., U2 ═ Ui. In the case where the leakage voltage is in the negative half-cycle, the first voltage is the reference voltage VREF, i.e., U1 is VREF. U2 ═ - (R5/R3 ═ Ui + R5/R4 ═ U1), where the reference voltage VREF is 0v, R3 ═ R5, R5 ═ 2R4, so the second voltage is the fourth voltage, i.e., U2 ═ Ui.

It will be appreciated that after the leakage voltage Ui passes through the comparator module 200 and the adder module 300, a second voltage is obtained, and in the positive half period, the second voltage U2 is the same as the leakage voltage Ui, and in the negative half period, the second voltage U2 is opposite to the leakage voltage Ui, i.e., -Ui. The second voltage U2 thus corresponds to a full-wave rectified voltage of the ac leakage voltage Ui during the entire cycle.

In an embodiment, as shown in fig. 2 and fig. 3, the driving module 500 includes an amplifier 510 and a thyristor 520, wherein an input terminal of the amplifier 510 is connected to the second output terminal, and is configured to amplify the second voltage U2 to obtain a third voltage U3; the thyristor 520 is connected to the output of the amplifier 510 for driving the protection switch 600, which is arranged in the circuit of the ac power supply 10, to open according to the third voltage U3.

Further, the amplifier 510 is a differential amplifier for amplifying the second voltage U2. Since the second voltage U2 has a small voltage value and cannot drive the thyristor 520 to turn off the protection switch 600, a differential amplifier is added to the leakage protection circuit, and the differential amplifier amplifies the second voltage U2 to obtain the third voltage U3.

The thyristor 520 rectifier element is a high-power semiconductor device with a four-layer structure having three PN junctions, and is also called a thyristor. The semiconductor device has the characteristics of small volume, relatively simple structure, strong function and the like, and is one of the commonly used semiconductor devices. The device is widely applied to various electronic equipment and electronic products, and is mainly used for controllable rectification, inversion, frequency conversion, voltage regulation, contactless switch and the like.

Use the utility model discloses a leakage protection circuit, as shown in fig. 3 schematic diagram, wherein, reference voltage is 0V, and first syntropy input is first operational amplifier U31A's syntropy input, and first reverse input is first operational amplifier U31A's reverse input end, and first output is the common end of cathode terminal of first diode D31 and the anode terminal connection of second diode D32. The second inverting input is the inverting input of the second operational amplifier U31B, the second inverting input is the inverting input of the second operational amplifier U31B, and the second output is the output of the second operational amplifier U31B. Wherein, R1 ═ R2, R3 ═ R5, and R5 ═ 2R 4.

When the leakage voltage Ui is higher than 0V, the output terminal of the first operational amplifier U31A outputs a voltage with a polarity opposite to that of the leakage voltage, i.e., a negative voltage, at this time, the second diode D32 is turned on, the first diode D31 is turned off, and further, the second output terminal outputs a first voltage U1 with a polarity opposite to that of the leakage voltage, where U1 is-Ui. The first operational amplifier U31B inversely adds the leakage voltage Ui and the first voltage U1, and outputs a second voltage U2, where U2 ═ - (R5/R3 ═ Ui + R5/R4 ═ U1), and thus U2 ═ Ui;

when the leakage voltage Ui is lower than 0V, the output terminal of the first operational amplifier U31A has a voltage opposite to the leakage voltage, i.e., a positive voltage, at which the first diode D31 is turned on, the second diode D32 is turned off, and the voltage output from the first output terminal is clamped to 0V, and U1 is 0V. The second operational amplifier U31B inversely adds the leakage voltage Ui and the first voltage U1, and outputs a second voltage U2, where U2 ═ - (R5/R3 ═ Ui + R5/R4 ═ U1), and therefore U2 ═ Ui.

Thus, during an entire ac cycle, U2 ═ Ui |.

The second voltage U2 is connected to the non-inverting input terminal of the operational amplifier U31C, the output terminal of the operational amplifier U31C outputs a third voltage U3, and the third voltage U3 drives the thyristor 520 to turn off the protection switch 600.

When a human body touches the shell of the electric leakage household appliance by mistake, the shell of the electric leakage household appliance, the human body and the ground form an electric leakage loop and generate electric leakage, the electric leakage detection module 100 detects the electric leakage, and generates electric leakage voltage Ui based on the electric leakage, and no matter whether an electric shock phenomenon occurs in a positive half cycle or a negative half cycle of an alternating current power supply loop, a protection circuit can disconnect a protection switch 600 in the power supply loop in time, so that the electric leakage loop is disconnected, and personal safety is ensured.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An earth leakage protection circuit, which is applied in an AC power supply loop, is characterized by comprising:

2. The leakage protection circuit of claim 1, wherein the comparator module comprises a first operational amplifier, a first reverse resistor, a first feedback resistor, a first diode, and a second diode;

the reverse input end of the first operational amplifier is connected with the electric leakage detection module through the first reverse resistor;

the same-direction input end of the first operational amplifier is connected with the reference voltage;

the output end of the first operational amplifier is connected with the anode of the first diode, and the output end of the first operational amplifier is also connected with the cathode of the second diode;

the cathode of the first diode is connected with the anode of the second diode and the second reverse input end through the first feedback resistor.

3. The leakage protection circuit of claim 2, wherein the first reverse resistor and the first feedback resistor have the same resistance.

4. The leakage protection circuit of claim 1, wherein the adder module comprises a second operational amplifier, a second inverting resistor, a third inverting resistor, and a second feedback resistor;

one end of the second reverse resistor is connected with the electric leakage detection module, and the other end of the second reverse resistor is connected with the reverse input end of the second operational amplifier;

one end of the third reverse resistor is connected with the first output end, and the other end of the third reverse resistor is connected with the reverse input end of the second operational amplifier;

one end of the second feedback resistor is connected with the other end of the second reverse resistor, and the other end of the second feedback resistor is connected with the output end of the second operational amplifier and connected with the driving module.

5. The leakage protection circuit of claim 4,

the resistance value of the second reverse resistor is the same as that of the second feedback resistor, and the resistance value of the second feedback resistor is twice that of the third reverse resistor.

6. The leakage protection circuit of claim 1, wherein the driving module comprises an amplifier and a thyristor, and an input terminal of the amplifier is connected to the second output terminal and is configured to amplify the second voltage to obtain a third voltage; and the controllable silicon is connected with the output end of the amplifier and used for driving a protection switch arranged on the alternating current power supply loop to be switched off according to the third voltage.

7. The leakage protection circuit of claim 6, wherein the amplifier is a differential amplifier.

8. The leakage protection circuit of claim 1, wherein the reference voltage is 0V.