A circuit for simulating a leakage current with a dc generated leakage protection device

Abstract

The application is suitable for the field of power distribution technology, and relates to a circuit for simulating leakage current by using direct current to generate a leakage protection device, which comprises resistance R5, resistance R8, resistance R13, triode Q2 and capacitor C2; further comprises resistance R1, resistance R2, resistance R9, capacitor C1 and operational amplifier U1A; further comprises resistance R3, resistance R4 and operational amplifier chip U1B; further comprises resistance R6, resistance R12, resistance R15, triode Q1 and triode Q3; further comprises socket XS1, which is connected with a leakage current transformer. The application realizes the simulation of leakage current in the form of sinusoidal alternating current through the circuit, and can simulate the waveform generated when leakage occurs in the real situation, so that the detection of leakage current measuring devices and action devices is more reliable, system loss is reduced, and the precision of leakage protection detection is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power distribution, and particularly relates to a circuit for simulating leakage current by using direct current to generate a leakage protection device. BACKGROUND

[0002] The leakage protection device is mainly used to protect the human body from electric shock when a device has a leakage fault, and the function involves the protection of personal and property safety. Therefore, the reliability of the protection action of the leakage detection and action device needs to be tested periodically. The leakage protection device includes a residual current operated circuit breaker, a leakage protection switch, etc. The leakage protection device actively generates a simulated leakage current to trigger the leakage protection action through an external trigger test jump function, and detects whether the leakage measurement device and the leakage protection action device are working normally.

[0003] With the intelligent development of leakage protection device products, high-efficiency switching power supplies will replace low-efficiency traditional power frequency transformer linear power supplies. In this background, the leakage circuit breaker often directly adopts a direct current square wave form to generate a simulated leakage current. The direct current square wave simulated leakage current is directly input to the test coil of the leakage current transformer. According to Faraday's law of electromagnetic induction, since the input is a square wave signal, the time of current mutation is extremely short. Therefore, the signal output at the measurement end is a sawtooth wave signal with extremely low amplitude. In order to meet the leakage current action threshold requirement, the input current needs to be increased, which leads to an increase in system invalid loss. In addition, the distorted sawtooth wave waveform cannot reflect the characteristics of the alternating leakage current waveform, which may cause deviation in the detection and judgment of the test current. Patent application No. CN211505856U provides a leakage current transformer detection circuit for a leakage circuit breaker, which includes a connector P5, a triode V2, and an operational amplifier chip U2D. The 1 pin of the connector P5 is connected to a test jump resistor R49. The 2 pin of the connector P5 is connected to the triode V2. The 3 pin of the connector P5 is connected to a current limiting resistor R48 and the operational amplifier chip U2D. The 3 pin and the 4 pin of the connector P5 are connected to a sampling resistor R47. The 4 pin of the connector P5 is connected to the ground. The reverse input end of the operational amplifier chip U2D is connected to a resistor R51 and a resistor R53. The other end of the resistor R53 is connected to the output end of the operational amplifier chip U2D. The other end of the resistor R51 is connected to the ground. The current limiting resistor R48 and the ground end of the resistor R51 are connected to a capacitor C17. The output end of the operational amplifier chip U2D is connected to a resistor R50. The resistor R50 is connected to a capacitor C10 with the other end connected to the ground. The resistor R50 is connected to the ADC sampling port of the main chip. This patent has the same drawbacks as the prior art, and the simulated current generation method still uses a direct current square wave method.

[0004] Therefore, how to eliminate the use of DC square waves to generate simulated leakage current in existing technologies, thereby reducing system losses and improving the accuracy of leakage protection detection, is a problem that urgently needs to be solved by those in this technical field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a circuit that uses DC to generate a leakage current to simulate leakage current in a leakage protection device, thereby solving the problems of high system losses and low leakage protection detection accuracy caused by using DC square waves to generate simulated leakage current in existing technologies.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This invention provides a circuit for simulating leakage current using a DC-generated leakage protection device, comprising:

[0008] The system includes resistors R5, R8, and R13, transistor Q2, and capacitor C2. One end of resistor R5 is connected to an external power supply. The other end of resistor R5 is connected to the collector of transistor Q2 and one end of resistor R8. The emitter of transistor Q2 is grounded. The two ends of capacitor C2 are connected to the other end of resistor R8 and the emitter of transistor Q2. The two ends of resistor R13 are connected to the microcontroller and the base of transistor Q2. The system also includes resistors R1, R2, and R9, capacitor C1, and operational amplifier U1A. One end of resistor R1 is connected to the other end of resistor R8 and one end of resistor R9. The other end of resistor R1 is connected to one end of resistor R2 and the second pin of operational amplifier U1A. The other end of resistor R2 is connected to one end of capacitor C1 and the first pin of operational amplifier U1A. The other end of capacitor C1 is connected to the other end of resistor R9. The system also includes resistor R3. The system includes a resistor R4 and an operational amplifier chip U1B. One end of resistor R3 is connected to one end of resistor R4 and the sixth pin of operational amplifier chip U1B. The other end of resistor R3 is grounded. The other end of resistor R4 is connected to the seventh pin of operational amplifier chip U1B. The system also includes resistors R6, R12, and R15, transistors Q1 and Q3. One end of resistor R6 is connected to the emitter of transistor Q1. The other end of resistor R6 is connected to one end of resistor R15. The other end of resistor R15 is connected to the emitter of transistor Q3. One end of resistor R12 is connected to the other end of resistor R4 and the seventh pin of operational amplifier chip U1B. The other end of resistor R12 is connected to the base of transistor Q1 and the base of transistor Q3. The collector of transistor Q1 is connected to an external power supply, and the collector of transistor Q3 is grounded. Finally, the system includes a socket XS1 connected to a leakage current transformer.

[0009] Furthermore, it also includes a resistor R14, one end of which is connected to the collector of the transistor Q2 and one end of the resistor R8, and the other end of which is connected to the emitter of the transistor Q2 and one end of the capacitor C2.

[0010] Furthermore, it also includes a resistor R10 and a capacitor C3. One end of the resistor R10 is connected to the other end of the resistor R9 and the other end of the capacitor C1, respectively. The other end of the resistor R10 is connected to one end of the capacitor C3 and the third pin of the operational amplifier U1A, respectively. The other end of the capacitor C3 is grounded.

[0011] Furthermore, it also includes a resistor R7, one end of which is connected to one end of the capacitor C1 and the first pin of the operational amplifier U1A, and the other end of which is connected to the fifth pin of the operational amplifier chip U1B.

[0012] Furthermore, the first and second pins of the socket XS1 are connected to the measuring coil of the leakage current transformer to output leakage current measurement signals. The third and fourth pins of the socket XS1 are connected to the test coil of the leakage current transformer. The analog leakage current signal is input through the third and fourth pins, and the leakage current is detected through the first and second pins.

[0013] Furthermore, when the leakage current test trip operation is triggered, the microcontroller generates a square wave signal I0_Test with a frequency of 50Hz, a duty cycle of 50%, and a peak value of 3.3V or 5V.

[0014] Compared with the prior art, the circuit for generating leakage current protection devices using DC power provided by this invention has at least the following advantages:

[0015] Existing technologies often directly generate simulated leakage current using DC square waves. By directly inputting a DC square wave into the test coil of a leakage current transformer to simulate leakage current, the output signal at the measurement end is a sawtooth wave signal with extremely low amplitude. Due to the small amplitude of the sawtooth wave at the measurement end, an increased square wave input current is required to meet the leakage current action threshold requirement, leading to increased system ineffective losses. Furthermore, the distorted sawtooth wave waveform cannot reflect the characteristics of AC leakage current waveforms, potentially causing errors in the detection and judgment of the test current. This invention converts the input I0_Test square wave signal into an output triangular wave signal using a designed circuit. The designed integrator circuit then converts the triangular wave signal into a sine wave signal, and the designed non-inverting amplifier circuit amplifies the sine wave signal, realizing a sinusoidal AC simulated leakage current. This can simulate the waveform of leakage current generation under real-world conditions, making the detection of leakage current measurement devices and action devices more reliable, reducing system losses, and improving the accuracy of leakage current protection detection. Attached Figure Description

[0016] To more clearly illustrate the solution of the present invention, a brief introduction will be given to the drawings used in the description of the embodiments below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 A circuit diagram of a circuit that uses a DC-generated leakage protection device to simulate leakage current, provided for an embodiment of the present invention;

[0018] Figure 2 The waveform diagram of converting the square wave signal I0_Test into a triangular wave signal at point U1 in a circuit that uses a DC leakage current generation leakage protection device to simulate leakage current in an embodiment of the present invention;

[0019] Figure 3 The waveform diagram of converting the triangular wave signal at point U1 into a sine wave signal at point U2 in a circuit that uses a DC leakage current generation leakage protection device to simulate leakage current in an embodiment of the present invention.

[0020] Figure 4 The waveform diagram of converting the sinusoidal signal at point U2 to the sinusoidal signal at point U3 in a circuit that uses a DC-generated leakage protection device to simulate leakage current in an embodiment of the present invention.

[0021] Figure 5 The waveform diagram shows the conversion of the sinusoidal signal at point U3 to the sinusoidal signal at point U4 in a circuit that uses a DC-generated leakage protection device to simulate leakage current, as provided in an embodiment of the present invention. Detailed Implementation

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as “length,” “width,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” indicate orientations or positions based on the orientations or positions shown in the accompanying drawings and are for ease of description only, and should not be construed as limiting the technical solution.

[0023] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a particular order. In the specification, claims, and accompanying drawings of this invention, when an element is referred to as "fixed to," "mounted to," "disposed of," or "connected to" another element, it may be directly or indirectly located on that other element. For example, when an element is referred to as "connected to" another element, it may be directly or indirectly connected to that other element.

[0024] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] This invention provides a circuit for simulating leakage current using a DC power source in a leakage current protection device, applied in the leakage current detection process of the leakage current protection device. The circuit for simulating leakage current using a DC power source in a leakage current protection device includes:

[0026] The system includes resistors R5, R8, and R13, transistor Q2, and capacitor C2. One end of resistor R5 is connected to an external power supply, and the other end of resistor R5 is connected to the collector of transistor Q2 and one end of resistor R8. The emitter of transistor Q2 is grounded. The two ends of capacitor C2 are connected to the other end of resistor R8 and the emitter of transistor Q2. The two ends of resistor R13 are connected to the microcontroller and the base of transistor Q2. The system also includes resistors R1, R2, and R9, capacitor C1, and operational amplifier U1A. One end of resistor R1 is connected to the other end of resistor R8 and one end of resistor R9. The other end of resistor R1 is connected to one end of resistor R2 and the second pin of operational amplifier U1A. The other end of resistor R2 is connected to one end of capacitor C1 and the first pin of operational amplifier U1A. The other end of capacitor C1 is connected to the other end of resistor R9. The system includes resistors R3 and R4, and operational amplifier chip U1B. One end of resistor R3 is connected to one end of resistor R4 and pin 6 of operational amplifier chip U1B. The other end of resistor R3 is grounded. The other end of resistor R4 is connected to pin 7 of operational amplifier chip U1B. The system also includes resistors R6, R12, and R15, transistors Q1 and Q3. One end of resistor R6 is connected to the emitter of transistor Q1. The other end of resistor R6 is connected to one end of resistor R15. The other end of resistor R15 is connected to the emitter of transistor Q3. One end of resistor R12 is connected to the other end of resistor R4 and pin 7 of operational amplifier chip U1B. The other end of resistor R12 is connected to the base of transistor Q1 and the base of transistor Q3. The collector of transistor Q1 is connected to an external power supply, and the collector of transistor Q3 is grounded. Finally, the system includes socket XS1, which is connected to a leakage current transformer.

[0027] This invention simulates leakage current in the form of sinusoidal AC through circuitry, which can simulate the waveform when leakage occurs in real-world conditions. This makes the detection of leakage current measuring devices and operating devices more reliable, reduces system losses, and improves the accuracy of leakage protection detection.

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0029] This invention provides a circuit for simulating leakage current in a leakage current protection device using DC power, which is applied in the leakage current detection process of the leakage current protection device, such as... Figure 1 As shown, in this embodiment, the circuit for simulating leakage current using a DC-generated leakage protection device includes:

[0030] The circuit consists of resistors R5, R8, R13, and R14, transistor Q2, and capacitor C2. One end of resistor R5 is connected to an external power supply, and the other end of resistor R5 is connected to the collector of transistor Q2 and one end of resistor R8. The emitter of transistor Q2 is grounded. The two ends of capacitor C2 are connected to the other end of resistor R8 and the emitter of transistor Q2. The two ends of resistor R13 are connected to the microcontroller and the base of transistor Q2. One end of resistor R14 is connected to the collector of transistor Q2 and one end of resistor R8. The other end of resistor R14 is connected to the emitter of transistor Q2 and one end of capacitor C2. The terminals are connected respectively; it also includes resistors R1, R2, R9, and R10, capacitors C1 and C3, and operational amplifier U1A. One end of resistor R1 is connected to the other end of resistor R8 and one end of resistor R9. The other end of resistor R1 is connected to one end of resistor R2 and the second pin of operational amplifier U1A. The other end of resistor R2 is connected to one end of capacitor C1 and the first pin of operational amplifier U1A. The other end of capacitor C1 is connected to the other end of resistor R9. One end of resistor R10 is connected to the other end of resistor R9 and the other end of capacitor C1. Resistor R10... The other end is connected to one end of capacitor C3 and the third pin of operational amplifier U1A, respectively, and the other end of capacitor C3 is grounded; it also includes resistors R3, R4, R7 and operational amplifier chip U1B, one end of resistor R3 is connected to one end of resistor R4 and the sixth pin of operational amplifier chip U1B, the other end of resistor R3 is grounded, the other end of resistor R4 is connected to the seventh pin of operational amplifier chip U1B, one end of resistor R7 is connected to one end of capacitor C1 and the first pin of operational amplifier U1A, and the other end of resistor R7 is connected to the fifth pin of operational amplifier chip U1B; it also includes resistors R6 and R... 12. Resistors R15, transistors Q1 and Q3; one end of resistor R6 is connected to the emitter of transistor Q1, and the other end of resistor R6 is connected to one end of resistor R15; the other end of resistor R15 is connected to the emitter of transistor Q3; one end of resistor R12 is connected to the other end of resistor R4 and the seventh pin of operational amplifier chip U1B; the other end of resistor R12 is connected to the base of transistor Q1 and the base of transistor Q3; the collector of transistor Q1 is connected to an external power supply, and the collector of transistor Q3 is grounded; also includes socket XS1, which is connected to a leakage current transformer.

[0031] Furthermore, the following is combined with Figures 1 to 5 The working principle of the circuit for simulating leakage current using a DC-generated leakage protection device provided in this embodiment of the invention will be explained as follows:

[0032] Socket XS1 connects to a leakage current transformer. The first and second pins of socket XS1 are connected to the measuring coil of the leakage current transformer to output leakage current measurement signals. The third and fourth pins of socket XS1 are connected to the test coil of the leakage current transformer. A simulated leakage current signal is input through the third and fourth pins, and the leakage current is detected through the first and second pins. When the leakage current test trip operation is triggered, the microcontroller generates a square wave signal I0_Test with a frequency of 50Hz, a duty cycle of 50%, and a peak value of 3.3V or 5V.

[0033] The circuit consisting of resistors R5, R8, R13, R14, transistor Q2, and capacitor C2 converts the input square wave signal I0_Test into a triangular wave signal output at point U1. The I0_Test signal is connected to the microcontroller, and the transistor Q2 is driven by the current-limiting resistor R13 to achieve conduction and cutoff. Resistors R5 and R8 are current-limiting resistors, and capacitor C2 is a charging and discharging capacitor, which can slow down the rising and falling edges of the square wave to form a triangular wave. Figure 2 As shown, an integrating circuit consisting of resistors R1, R2, R9, and R10, capacitors C1 and C3, and operational amplifier U1A converts the triangular wave of U1 into a sine wave of U2. R1 and R2 are the adjusting resistors for the integrating operational amplifier circuit, and C1 is the integrating capacitor. The waveform of U2 after conversion is shown below. Figure 3 As shown, a non-inverting amplifier circuit composed of resistors R3, R4, R7, and operational amplifier chip U1B amplifies the sinusoidal signal of U2. Resistors R3 and R4 are feedback resistors. Therefore, U3 can be calculated as U2(R4+R3) / R3. The waveform of U3 is as follows. Figure 4 As shown; the current amplifier circuit consists of resistors R6, R12, and R15, and transistors Q1 and Q3. Transistors Q1 and Q3 form a half-bridge circuit. Resistor R12 is the current-limiting resistor for the half-bridge drive, and resistors R6 and R15 are also current-limiting resistors to prevent overcurrent damage to the transistors when both half-bridges are conducting simultaneously. The input voltage of U3 is between 0 and 12V. Transistors Q1 and Q3 periodically pass through the cutoff region, amplification region, and saturation region. Current is amplified through the half-bridge circuit, increasing the load-carrying capacity of U4. The waveform of U4 is shown below. Figure 5 As shown.

[0034] The third pin of the leakage current transformer test coil is connected to the system's 5V power supply to simulate leakage current. The leakage current I0 = (U4 - 5V) / (R11 + RL + R), where R is the resistance value of R6 or R15, and R6 and R15 have the same resistance value; RL is the internal resistance of the leakage current test coil. Therefore, it can be seen that the waveform of I0 is a sine wave, rather than the DC square wave in the existing technology.

[0035] The circuit described in the above embodiment, which uses DC to generate a leakage current to simulate leakage current in a leakage current protection device, differs from existing technologies. Existing technologies often directly generate simulated leakage current using a DC square wave, inputting the DC square wave directly to the test coil of the leakage current transformer. This results in a sawtooth wave signal with extremely low amplitude at the measurement end. Due to the small amplitude of the sawtooth wave at the measurement end, an increased square wave input current is required to meet the leakage current action threshold, leading to increased system ineffective losses. Furthermore, the distorted sawtooth wave waveform cannot reflect the characteristics of AC leakage current waveforms, potentially causing errors in the detection and judgment of the test current. This invention, through its designed circuit, converts the input I0_Test square wave signal into an output triangular wave signal. The designed integrator circuit then converts the triangular wave signal into a sine wave signal, and the designed non-inverting amplifier circuit amplifies the sine wave signal, achieving a sinusoidal AC form of simulated leakage current. This can simulate the waveform of leakage current generation under real-world conditions, making the detection of leakage current measurement devices and action devices more reliable, reducing system losses, and improving the accuracy of leakage current protection detection.

[0036] Obviously, the embodiments described above are merely preferred embodiments of the present invention, and not all embodiments. The accompanying drawings illustrate preferred embodiments of the present invention, but do not limit the scope of the patent. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this invention.

Claims

1. A circuit that uses DC to generate a leakage current protection device to simulate leakage current, characterized in that, include: The system includes resistors R5, R8, and R13, transistor Q2, and capacitor C2. One end of resistor R5 is connected to an external power supply. The other end of resistor R5 is connected to the collector of transistor Q2 and one end of resistor R8. The emitter of transistor Q2 is grounded. The two ends of capacitor C2 are connected to the other end of resistor R8 and the emitter of transistor Q2. The two ends of resistor R13 are connected to the microcontroller and the base of transistor Q2. The system also includes resistors R1, R2, and R9, capacitor C1, and operational amplifier U1A. One end of resistor R1 is connected to the other end of resistor R8 and one end of resistor R9. The other end of resistor R1 is connected to one end of resistor R2 and the second pin of operational amplifier U1A. The other end of resistor R2 is connected to one end of capacitor C1 and the first pin of operational amplifier U1A. The other end of capacitor C1 is connected to the other end of resistor R9. The system also includes resistor R3. The system includes a resistor R4 and an operational amplifier chip U1B. One end of resistor R3 is connected to one end of resistor R4 and the sixth pin of operational amplifier chip U1B, and the other end of resistor R3 is grounded. The other end of resistor R4 is connected to the seventh pin of operational amplifier chip U1B. The system also includes resistors R6, R12, and R15, transistors Q1 and Q3. One end of resistor R6 is connected to the emitter of transistor Q1, and the other end of resistor R6 is connected to one end of resistor R15. The other end of resistor R15 is connected to the emitter of transistor Q3. One end of resistor R12 is connected to the other end of resistor R4 and the seventh pin of operational amplifier chip U1B. The other end of resistor R12 is connected to the base of transistor Q1 and the base of transistor Q3. The collector of transistor Q1 is connected to an external power supply, and the collector of transistor Q3 is grounded. Finally, the system includes a socket XS1 connected to a leakage current transformer. It also includes a resistor R14, one end of which is connected to the collector of the transistor Q2 and one end of the resistor R8, and the other end of the resistor R14 is connected to the emitter of the transistor Q2 and one end of the capacitor C2. It also includes a resistor R10 and a capacitor C3. One end of the resistor R10 is connected to the other end of the resistor R9 and the other end of the capacitor C1, respectively. The other end of the resistor R10 is connected to one end of the capacitor C3 and the third pin of the operational amplifier U1A, respectively. The other end of the capacitor C3 is grounded.

2. The circuit for simulating leakage current using a DC-generated leakage protection device according to claim 1, characterized in that, It also includes a resistor R7, one end of which is connected to one end of the capacitor C1 and the first pin of the operational amplifier U1A, and the other end of the resistor R7 is connected to the fifth pin of the operational amplifier chip U1B.

3. The circuit for simulating leakage current using a DC-generated leakage protection device according to claim 1, characterized in that, The first and second pins of the socket XS1 are connected to the measuring coil of the leakage current transformer and are used to output leakage current measurement signals. The third and fourth pins of the socket XS1 are connected to the test coil of the leakage current transformer. The analog leakage current signal is input through the third and fourth pins, and the leakage current is detected through the first and second pins.

4. The circuit for simulating leakage current using a DC-generated leakage protection device according to claim 1, characterized in that, When the leakage current test trip operation is triggered, the microcontroller generates a square wave signal I0_Test with a frequency of 50Hz, a duty cycle of 50%, and a peak value of 3.3V or 5V.

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