CN210806721U - Leakage protection circuit of intelligent miniature circuit breaker - Google Patents
Leakage protection circuit of intelligent miniature circuit breaker Download PDFInfo
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- CN210806721U CN210806721U CN201921476592.9U CN201921476592U CN210806721U CN 210806721 U CN210806721 U CN 210806721U CN 201921476592 U CN201921476592 U CN 201921476592U CN 210806721 U CN210806721 U CN 210806721U
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Abstract
The utility model relates to an electric leakage protection circuit of an intelligent miniature circuit breaker, which comprises a current sampling circuit, a signal amplifying circuit, a rectifying circuit and a control circuit; the current sampling circuit is arranged on the detected live wire and the detected zero line and is used for detecting a leakage current signal and converting the leakage current signal into a leakage voltage signal; the signal amplifying circuit is connected with the current sampling circuit and used for amplifying the leakage voltage signal; the rectifying circuit is connected with the signal amplifying circuit and is used for converting the leakage voltage signal into a direct current leakage voltage signal; the control circuit is connected with the rectifying circuit and used for comparing the direct current leakage voltage signal with a preset voltage signal and outputting a protection signal, so that correct identification and effective protection of leakage current are realized.
Description
Technical Field
The utility model relates to a circuit breaker technical field especially relates to a miniature circuit breaker's of intelligence earth leakage protection circuit.
Background
The intelligent miniature circuit breaker is one of a plurality of circuit breakers, is widely applied to various power utilization places such as industries, businesses, high-rise and civil houses at present, and has the advantages of small volume, easiness in operation, strong breaking capacity, high reliability and the like. In recent years, with the development of smart grid technology, electrical devices are increasing and diversified, and particularly, with the development of power electronic technology, electrical devices such as microwave ovens, frequency converters, UPS power supplies and the like are widely applied, and when leakage faults occur to the electrical devices, the waveform of generated leakage current is often very complex. At this time, the conventional intelligent miniature circuit breaker cannot accurately protect such leakage current, and cannot meet the requirement of safe power utilization.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides an intelligence miniature circuit breaker's earth leakage protection circuit can correctly discern and effectively protect leakage current.
An electric leakage protection circuit of an intelligent miniature circuit breaker comprises a current sampling circuit, a signal amplification circuit, a rectification circuit and a control circuit;
the current sampling circuit is arranged on the detected live wire and zero line and is used for detecting a leakage current signal and converting the leakage current signal into a leakage voltage signal;
the signal amplification circuit is connected with the current sampling circuit and is used for amplifying the leakage voltage signal;
the rectifying circuit is connected with the signal amplifying circuit and is used for converting the leakage voltage signal into a direct current leakage voltage signal;
the control circuit is connected with the rectifying circuit and used for comparing the direct current leakage voltage signal with a preset voltage signal and outputting a protection signal.
In one embodiment, the current sampling circuit includes:
the current transformer is arranged on the detected live wire and the detected zero line;
and the sampling resistor is connected between the secondary side windings of the current transformer.
In one embodiment, the signal amplification circuit comprises a first operational amplifier, a first resistor and a second resistor;
the first resistor is connected between the negative input end of the first operational amplifier and the current sampling circuit;
the second resistor is connected between the negative input end of the first operational amplifier and the output end of the first operational amplifier;
and the negative input end of the first operational amplifier is connected with a first reference voltage.
In one embodiment, the first reference voltage is set to 1.65V dc.
In one embodiment, the rectifying circuit comprises a second operational amplifier, a third operational amplifier, a first diode, a second diode, a third diode, a fourth diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a first capacitor;
the third resistor is connected between the negative input end of the second operational amplifier and a second reference voltage; the fourth resistor is connected between the negative input end of the second operational amplifier and the output end of the second operational amplifier; the fifth resistor is connected between the positive input end of the second operational amplifier and a third reference voltage; the sixth resistor is connected between the negative input end of the third operational amplifier and the signal amplification circuit; the seventh resistor is connected between the negative input terminal of the third operational amplifier and the output terminal of the third operational amplifier; the eighth resistor is connected between the positive input end of the third operational amplifier and a fourth reference voltage;
the first diode is connected between the positive input end of the second operational amplifier and the signal amplification circuit; the second diode is connected between the output end of the second operational amplifier and the control circuit; the third diode is connected between the negative input end of the third operational amplifier and the signal amplification circuit and is connected with the sixth resistor in series; the fourth diode is connected between the output end of the third operational amplifier and the control circuit;
the first capacitor is connected between a pull-up voltage terminal and a ground terminal of the second operational amplifier.
In one embodiment, the control circuit comprises a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, an adjustable potentiometer, a fifth diode, a second capacitor, a switching tube and a comparator;
the ninth resistor and the second capacitor are connected in parallel between the positive input end and the ground end of the comparator; the fifth diode is connected between the output end of the rectifying circuit and the positive input end of the comparator; the adjustable potentiometer and the tenth resistor are connected in parallel between the negative input end of the comparator and a preset voltage signal end; the eleventh resistor is connected between the negative input end of the comparator and the ground end; the twelfth resistor is connected between the source terminal and the grounding terminal of the switching tube; and the drain end of the switching tube is connected with the negative input end of the comparator, and the grid end of the switching tube and the thirteenth resistor are connected with the output end of the comparator in series.
In one embodiment, the switch tube is configured as an NMOS tube.
In an embodiment, the predetermined voltage signal of the predetermined voltage signal terminal is set to be dc 5V.
In one embodiment, the control circuit further comprises a single chip microcomputer, and the single chip microcomputer is connected to the output end of the comparator.
The leakage protection circuit of the intelligent miniature circuit breaker comprises a current sampling circuit, a signal amplification circuit, a rectification circuit and a control circuit; the current sampling circuit is arranged on the detected live wire and zero line and is used for detecting a leakage current signal and converting the leakage current signal into a leakage voltage signal; the signal amplification circuit is connected with the current sampling circuit and is used for amplifying the leakage voltage signal; the rectifying circuit is connected with the signal amplifying circuit and is used for converting the leakage voltage signal into a direct current leakage voltage signal; the control circuit is connected with the rectifying circuit and used for comparing the direct current leakage voltage signal with a preset voltage signal and outputting a protection signal, so that correct identification and effective protection of leakage current are realized.
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 schematic structural diagram of an earth leakage protection circuit of an intelligent miniature circuit breaker in a first embodiment;
FIG. 2 is a schematic diagram of a current sampling circuit and a signal amplification circuit in one embodiment;
FIG. 3 is a schematic diagram showing a structure of a rectifier circuit in one embodiment;
FIG. 4 is a schematic diagram of a control circuit according to one embodiment;
fig. 5 is a schematic structural diagram of a control circuit in another embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention 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 merely illustrative of the invention and are not intended to limit the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present invention. The first resistance and the second resistance are both resistances, but they are not the same resistance.
The utility model relates to an intelligence miniature circuit breaker's earth leakage protection circuit, as shown in FIG. 1, an intelligence miniature circuit breaker's earth leakage protection circuit, including current sampling circuit 100, signal amplification circuit 200, rectifier circuit 300 and control circuit 400. The current sampling circuit 100 is arranged on the detected live line L and the zero line N, and is used for detecting a leakage current signal and converting the leakage current signal into a leakage voltage signal; the signal amplifying circuit 200 is connected to the current sampling circuit 100, and is configured to amplify the leakage voltage signal; the rectifying circuit 300 is connected to the signal amplifying circuit 200, and is configured to convert the leakage voltage signal into a dc leakage voltage signal; the control circuit 400 is connected to the rectifying circuit 300, and configured to compare the dc leakage voltage signal with a preset voltage signal and output a protection signal.
The leakage protection circuit of the intelligent miniature circuit breaker correctly identifies and effectively protects leakage current.
It should be understood that the intelligent miniature circuit breaker can be roughly classified into two specifications of 2P (single-phase 2-stage circuit breaker) and 3P + n (three-phase power circuit breaker). 2P means that the live wire and the zero wire are controlled simultaneously, and the live wire and the zero wire have thermal tripping functions, and the modulus is 2 x 18 mm-36 mm; 3p + n refers to 4 connections for a three-phase line with a three-phase live line plus a neutral line. The leakage protection circuits of the intelligent miniature circuit breakers of the two specifications are the same, and the single-phase leakage protection circuit of the intelligent miniature circuit breaker of the 3p + n specification is taken as an example for explanation.
In one embodiment, as shown in fig. 2, the current sampling circuit 100 includes: and the current transformer CT is arranged on the detected live wire L and the detected zero line N. And the sampling resistor R0 is connected between the secondary side windings of the current transformer CT.
In this embodiment, the current transformer CT is disposed on the live line L and the neutral line N to be detected, and the sampling resistor R0 is connected between the secondary side windings. It is to be understood that the current transformer CT is used to detect the leakage current value, and the sampling resistor R0 converts the detected current into a voltage signal, and a leakage voltage signal. Therefore, the sampling resistor R0 can be an adjustable resistor, and the sampling value of the leakage current can be adjusted by adjusting the resistance value of the sampling resistor R0, so that the sampling precision is ensured.
In one embodiment, as shown in fig. 2, the signal amplifying circuit 200 includes a first operational amplifier U1, a first resistor R1, and a second resistor R2. The first resistor R1 is connected between the negative input terminal of the first operational amplifier U1 and the current sampling circuit 100; the second resistor R2 is connected between the negative input of the first operational amplifier U1 and the output of the first operational amplifier U1; the negative input of the first operational amplifier U1 is connected to a first reference voltage VREF 1.
In this embodiment, the current sampling circuit 100 outputs a leakage voltage signal through the sampling resistor R0, and the first reference voltage VREF1 is accessed through the first signal amplifier U1 to raise the voltage value of the sampled leakage voltage signal, so that the leakage voltage signal is raised to above the zero point as a whole. The first signal amplifier U1 then amplifies the amplitude of the leakage voltage signal. It can be understood that the measurement accuracy is related to the magnitude of the input voltage, and the signal is amplified and then measured, so that the measurement accuracy can be improved.
Specifically, taking the detected leakage current signal as 30mA as an example, the first signal amplifier U1 is set to LM2902PT, which can achieve 11 times amplification of the leakage voltage signal.
Specifically, the first reference voltage VREF1 is set to dc 1.65V. This value can raise the leakage voltage signal above zero as a whole.
In one embodiment, as shown in fig. 3, the rectifier circuit 300 includes a second operational amplifier U2, a third operational amplifier U3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a first capacitor C1.
Wherein the third resistor R3 is connected between the negative input terminal of the second operational amplifier U2 and the second reference voltage; the fourth resistor R4 is connected between the negative input terminal of the second operational amplifier U2 and the output terminal of the second operational amplifier U2; the fifth resistor R5 is connected between the positive input terminal of the second operational amplifier U2 and the third reference voltage; the sixth resistor R6 is connected between the negative input terminal of the third operational amplifier U3 and the signal amplification circuit; the seventh resistor R7 is connected between the negative input terminal of the third operational amplifier U3 and the output terminal of the third operational amplifier U3; the eighth resistor R8 is connected between the positive input of the third operational amplifier U3 and a fourth reference voltage.
The first diode D1 is connected between the positive input end of the second operational amplifier U2 and the signal amplification circuit; the second diode D2 is connected between the output of the second operational amplifier U2 and the control circuit; the third diode D3 is connected between the negative input terminal of the third operational amplifier U3 and the signal amplification circuit, and is connected in series with the sixth resistor R6; the fourth diode D4 is connected between the output of the third operational amplifier U3 and the control circuit.
The first capacitor C1 is connected between the pull-up voltage terminal of the second operational amplifier U2 and the ground terminal.
In this embodiment, the rectifier circuit 300 adopts a full-bridge push-pull scheme of four diodes (a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4) to flip the signal of the negative half shaft of the leakage voltage signal to the positive half shaft, so as to obtain the dc leakage voltage signal.
Specifically, the first capacitor C1 is used to reduce the influence of the pull-up voltage on the second operational amplifier U2, i.e., to reduce the high frequency interference introduced into the operational amplifier.
Specifically, the second operational amplifier U2 and the third operational amplifier U3 employ an LM2902PT operational amplifier. It has the characteristics of low noise, high input resistance and high gain.
In an embodiment, as shown in fig. 4, the control circuit 400 includes a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, an adjustable potentiometer RX, a fifth diode D5, a second capacitor C2, a switching tube Q1, and a comparator CMP.
The ninth resistor R9 and the second capacitor C2 are connected in parallel between the positive input terminal and the ground terminal of the comparator CMP; the fifth diode D5 is connected between the output terminal of the rectifying circuit and the positive input terminal of the comparator CMP; the adjustable potentiometer RX and the tenth resistor R10 are connected in parallel between the negative input terminal of the comparator CMP and the preset voltage signal terminal VCC; the eleventh resistor R11 is connected between the negative input terminal of the comparator CMP and the ground terminal; the twelfth resistor R12 is connected between the source terminal and the ground terminal of the switching tube Q1; the drain terminal of the switching tube Q1 is connected to the negative input terminal of the comparator CMP, and the gate terminal of the switching tube Q and the thirteenth resistor R13 are connected in series to the output terminal of the comparator CMP.
In this embodiment, the comparator CMP in the control circuit 400 compares the dc leakage voltage signal obtained from the rectifying circuit with the preset voltage signal of the preset voltage signal terminal VCC, and if the dc leakage voltage signal is greater than the preset voltage signal, the comparator CMP outputs a high level to drive the switching tube Q1 to be turned on, and further pull down the preset voltage signal of the preset voltage signal terminal VCC to achieve locking. Meanwhile, the high level output by the comparator CMP is sent to a singlechip and a relay (not shown) to control the opening of the intelligent miniature circuit breaker so as to play a role in leakage protection.
In one embodiment, the switch tube is configured as an NMOS tube.
It should be understood that the characteristics of the NMOS transistor are: the voltage difference VGS between the grid and the source is larger than a certain value, the grid is switched on, and the grid is switched off otherwise. Therefore, when the comparator CMP outputs a high level, the switching tube Q1 is turned on.
In one embodiment, the predetermined voltage signal of the predetermined voltage signal terminal VCC is set to be dc 5V.
In this embodiment, a voltage signal dc 5V is preset, a preset voltage signal terminal VCC enters an inverting terminal (i.e., a negative input terminal) of the comparator CMP after being connected to the adjustable potentiometer RX, and the amplitude of the preset voltage signal can be adjusted by adjusting the adjustable potentiometer RX, so as to adjust the amplitude of the leakage current protection action.
In an embodiment, as shown in fig. 5, the control circuit 400 further includes a single chip, and the single chip is connected to an output terminal of the comparator CMP.
In this embodiment, the high level output by the comparator CMP is sent to the single chip microcomputer to control the opening of the intelligent miniature circuit breaker, so as to play a role in leakage protection.
In this embodiment, a leakage protection method for an intelligent micro circuit breaker is further provided, which is suitable for the leakage protection circuit of the intelligent micro circuit breaker, and the method includes steps S100 to S300:
step S100: and acquiring a leakage current signal, and converting the leakage current signal into a leakage voltage signal.
Step S200: and amplifying the leakage voltage signal.
Step S300: and converting the amplified leakage voltage signal into a direct current leakage voltage signal.
Step S400: and comparing the direct current leakage voltage signal with a preset voltage signal and outputting a protection signal.
In this embodiment, referring to fig. 1, the leakage protection method of the intelligent miniature circuit breaker is suitable for the leakage protection circuit of the intelligent miniature circuit breaker, that is, the current sampling circuit 100 obtains a leakage current signal and converts the leakage current signal into a leakage voltage signal; the signal amplification circuit 200 amplifies the leakage voltage signal; the rectifying circuit 300 converts the amplified leakage voltage signal into a direct current leakage voltage signal; the control circuit 400 compares the dc leakage voltage signal with a predetermined voltage signal and outputs a protection signal. The specific implementation manner is described in detail in the leakage protection circuit of the intelligent miniature circuit breaker, and is not described herein again.
The leakage protection circuit of the intelligent miniature circuit breaker comprises a current sampling circuit 100, a signal amplification circuit 200, a rectification circuit 300 and a control circuit 400; the current sampling circuit 100 is arranged on the detected live wire and the detected zero line, and is used for detecting a leakage current signal and converting the leakage current signal into a leakage voltage signal; the signal amplifying circuit 200 is connected to the current sampling circuit 100, and is configured to amplify the leakage voltage signal; the rectifying circuit 300 is connected to the signal amplifying circuit 200, and is configured to convert the leakage voltage signal into a dc leakage voltage signal; the control circuit 400 is connected to the rectifying circuit 300, and is configured to compare the dc leakage voltage signal with a preset voltage signal, and output a protection signal, thereby implementing correct identification and effective protection of the leakage current.
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 represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (9)
1. The leakage protection circuit of the intelligent miniature circuit breaker is characterized by comprising a current sampling circuit, a signal amplification circuit, a rectification circuit and a control circuit;
the current sampling circuit is arranged on the detected live wire and zero line and is used for detecting a leakage current signal and converting the leakage current signal into a leakage voltage signal;
the signal amplification circuit is connected with the current sampling circuit and is used for amplifying the leakage voltage signal;
the rectifying circuit is connected with the signal amplifying circuit and is used for converting the leakage voltage signal into a direct current leakage voltage signal;
the control circuit is connected with the rectifying circuit and used for comparing the direct current leakage voltage signal with a preset voltage signal and outputting a protection signal.
2. The leakage protection circuit of the intelligent miniature circuit breaker as set forth in claim 1, wherein said current sampling circuit comprises:
the current transformer is arranged on the detected live wire and the detected zero line;
and the sampling resistor is connected between the secondary side windings of the current transformer.
3. The leakage protection circuit of the intelligent miniature circuit breaker as recited in claim 1, wherein said signal amplification circuit comprises a first operational amplifier, a first resistor and a second resistor;
the first resistor is connected between the negative input end of the first operational amplifier and the current sampling circuit;
the second resistor is connected between the negative input end of the first operational amplifier and the output end of the first operational amplifier;
and the negative input end of the first operational amplifier is connected with a first reference voltage.
4. The leakage protection circuit of an intelligent miniature circuit breaker of claim 3 wherein said first reference voltage is set to 1.65 DC.
5. The leakage protection circuit of the intelligent miniature circuit breaker according to claim 1, wherein said rectifying circuit comprises a second operational amplifier, a third operational amplifier, a first diode, a second diode, a third diode, a fourth diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a first capacitor;
the third resistor is connected between the negative input end of the second operational amplifier and a second reference voltage; the fourth resistor is connected between the negative input end of the second operational amplifier and the output end of the second operational amplifier; the fifth resistor is connected between the positive input end of the second operational amplifier and a third reference voltage; the sixth resistor is connected between the negative input end of the third operational amplifier and the signal amplification circuit; the seventh resistor is connected between the negative input terminal of the third operational amplifier and the output terminal of the third operational amplifier; the eighth resistor is connected between the positive input end of the third operational amplifier and a fourth reference voltage;
the first diode is connected between the positive input end of the second operational amplifier and the signal amplification circuit; the second diode is connected between the output end of the second operational amplifier and the control circuit; the third diode is connected between the negative input end of the third operational amplifier and the signal amplification circuit and is connected with the sixth resistor in series; the fourth diode is connected between the output end of the third operational amplifier and the control circuit;
the first capacitor is connected between a pull-up voltage terminal and a ground terminal of the second operational amplifier.
6. The leakage protection circuit of the intelligent miniature circuit breaker as recited in claim 1, wherein said control circuit comprises a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, an adjustable potentiometer, a fifth diode, a second capacitor, a switch tube and a comparator;
the ninth resistor and the second capacitor are connected in parallel between the positive input end and the ground end of the comparator; the fifth diode is connected between the output end of the rectifying circuit and the positive input end of the comparator; the adjustable potentiometer and the tenth resistor are connected in parallel between the negative input end of the comparator and a preset voltage signal end; the eleventh resistor is connected between the negative input end of the comparator and the ground end; the twelfth resistor is connected between the source terminal and the grounding terminal of the switching tube; and the drain end of the switching tube is connected with the negative input end of the comparator, and the grid end of the switching tube and the thirteenth resistor are connected with the output end of the comparator in series.
7. The leakage protection circuit of intelligent miniature circuit breaker according to claim 6, wherein said switching tube is configured as an NMOS tube.
8. The leakage protection circuit of an intelligent miniature circuit breaker as recited in claim 6, wherein said preset voltage signal of said preset voltage signal terminal is set to DC 5V.
9. The leakage protection circuit of an intelligent miniature circuit breaker according to claim 6, wherein said control circuit further comprises a single chip microcomputer, said single chip microcomputer being connected to an output terminal of said comparator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921476592.9U CN210806721U (en) | 2019-09-05 | 2019-09-05 | Leakage protection circuit of intelligent miniature circuit breaker |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921476592.9U CN210806721U (en) | 2019-09-05 | 2019-09-05 | Leakage protection circuit of intelligent miniature circuit breaker |
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| CN210806721U true CN210806721U (en) | 2020-06-19 |
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| CN201921476592.9U Active CN210806721U (en) | 2019-09-05 | 2019-09-05 | Leakage protection circuit of intelligent miniature circuit breaker |
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- 2019-09-05 CN CN201921476592.9U patent/CN210806721U/en active Active
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