A leakage protector with bidirectional leakage detection function

Abstract

This invention discloses a residual current device (RCD) with bidirectional leakage current detection function, comprising: an isolation module power supply A, whose input circuit is connected to the input side of the RCD and whose output circuit is connected to the DC bus VCC_24V; an isolation module power supply B, whose input circuit is connected to the output side of the RCD and whose output circuit is connected to the DC bus VCC_24V, with isolation module power supply A and isolation module power supply B connected in parallel; a main detection circuit H, which includes a leakage current detection chip U3, a leakage current acquisition circuit, and a neutral grounding detection circuit; a leakage current detection circuit D, which is used to acquire the grid phase synchronization signal and output it to the leakage current detection chip U3; and a trip execution and self-reset circuit I, which is used to control the energization and de-energization of the relay coil SOL2 and the reset of the silicon controlled rectifier (SCR). Compared with the prior art, this invention solves the problem that the disconnect-type bidirectional RCD cannot be reset when reverse energized after tripping, thus failing to achieve leakage current protection.

Description

Technical Field

[0001] This invention relates to the field of residual current device (RCD) technology, and in particular to an RCD with bidirectional leakage current detection function. Background Technology

[0002] A residual current device (RCD) is an electrical device that automatically disconnects the power supply when a circuit experiences a leakage current, in order to protect personal safety and prevent electrical fires. RCDs detect leakage current using the principle of electromagnetic induction.

[0003] Existing unidirectional residual current circuit breakers (GFCIs) pose a risk of electric shock if an external independent power source supplies power in reverse to the public grid. These external independent power sources include, but are not limited to, electric vehicle batteries, photovoltaic inverters, and external energy storage batteries. Bidirectional residual current circuit breakers (BD-GFCIs), on the other hand, can detect leakage faults and disconnect the circuit in both forward and reverse power supply modes. With the increasing prevalence of external distributed power sources capable of reverse power supply, bidirectional residual current circuit breakers need to be adapted to reverse power supply functionality to prevent leakage during reverse power supply and to prevent equipment damage in the event of severe leakage.

[0004] Bidirectional residual current devices (RCDs) can be classified according to their installation method or the state of the SW contacts when power is off. Based on installation method, they can be divided into portable, mobile bidirectional RCDs or fixed-installation bidirectional RCDs. Based on the state of the SW contacts when power is off, those with open SW contacts when neither the input nor output is energized are called open-type bidirectional RCDs, and those with closed SW contacts are called closed-type bidirectional RCDs. Closed-type bidirectional RCDs are simple to implement; they are simply based on unidirectional RCDs, with improvements to the reset mechanism to ensure the product resets even when power is off. Further details are omitted.

[0005] When a power outage occurs, and neither the input nor output terminals are energized, the SW contact of the tripping-type bidirectional residual current device (RCD) remains open. The RCD can only be reset by pressing the RESET button when a continuous current is supplied to the relay coil SOL2. While the SW contact is engaged, the current in the relay coil SOL2 is maintained; once the relay coil SOL2 is de-energized, the SW contact opens, and the RCD trips.

[0006] To achieve bidirectional leakage detection, the disconnect-type bidirectional leakage current protection device (GFCI) needs to be able to reset when reverse power is supplied. However, if the module power supply is only set at the input terminal, the circuit board will have no working voltage when reverse power is supplied, and the SW contacts will not be able to close. Summary of the Invention

[0007] The purpose of this invention is to provide a leakage current protector with bidirectional leakage current detection function, so as to solve the problem that the disconnect-type bidirectional leakage current protector cannot be reset when reverse power is supplied after tripping, thus failing to achieve leakage current protection.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a leakage current protector with bidirectional leakage current detection function, comprising:

[0009] The isolation module power supply A has its input circuit connected to the input side of the leakage current protector and its output circuit connected to the DC bus VCC_24V.

[0010] The input circuit of isolation module power supply B is connected to the output side of the leakage current protection device, and the output circuit is connected to the DC bus VCC_24V. Isolation module power supply A and isolation module power supply B are connected in parallel for power supply.

[0011] The main detection circuit H includes a leakage current detection chip U3, a leakage current acquisition circuit, and a neutral ground detection circuit. The leakage current acquisition circuit includes a leakage current detection magnetic ring ZCT3A, diode D10, diode D11, resistor R17, resistor R18, capacitor C11, and resistor R1. The leakage current signal acquired by the leakage current acquisition circuit is transmitted to the leakage current detection chip U3. The neutral ground detection circuit includes a neutral ground detection transformer ZCT4A, capacitor C9, capacitor C8, and resistor R20. When the neutral line output and the ground line are short-circuited, the neutral ground detection circuit generates an oscillation signal and transmits it to the leakage current detection chip U3.

[0012] The leakage current detection circuit D is used to collect the power grid phase synchronization signal and output it to the leakage current detection chip U3.

[0013] The tripping and self-reset circuit I is used to control the energization and de-energization of the relay coil SOL2 and the reset of the silicon controlled rectifier SCR after receiving the trigger signal from the leakage current detection chip U3.

[0014] As a further description of the above technical solution:

[0015] Both isolation module power supply A and isolation module power supply B are AC to DC isolation module power supplies.

[0016] As a further description of the above technical solution:

[0017] AC to DC isolation module power supplies are either high-frequency switching AC to DC isolation module power supplies or power frequency transformer type AC to DC isolation module power supplies.

[0018] As a further description of the above technical solution:

[0019] A varistor is connected in parallel between the live wire and the neutral wire on the input side of the residual current device (RCD).

[0020] As a further description of the above technical solution:

[0021] The output of the voltage regulator circuit F is connected to the analog detection power supply pin of the leakage current detection chip U3.

[0022] As a further description of the above technical solution:

[0023] The output of the voltage regulator circuit G is connected to the drive power pin of the leakage current detection chip U3.

[0024] As a further description of the above technical solution:

[0025] The main detection circuit H also includes a test circuit, which includes a TEST button and a resistor R19. The TEST button and the resistor R19 are connected in series and then connected across the live and neutral wires, and pass through the leakage current detection magnetic ring ZCT3A.

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] 1. In this invention, isolation module power supply A and isolation module power supply B form a bidirectional power supply architecture. Both isolation module power supply A and isolation module power supply B output +24V DC voltage and are electrically isolated from each other, ensuring that the withstand voltage performance of the input and output terminals meets regulatory requirements under tripping conditions. Regardless of whether the input terminal is powered in the forward direction or the output terminal is powered in the reverse direction, the relay can be powered through the corresponding isolated power supply to achieve reset and normal protection operation, solving the limitation that unidirectional leakage current protectors cannot work when powered in the reverse direction. The leakage current protector will not conduct directly when powered in the reverse direction, avoiding the risk of accidental energization caused by reverse power supply after power failure.

[0028] 2. In this invention, the residual current device (RCD) integrates neutral grounding fault protection, input surge protection, and lifespan self-monitoring functions in addition to basic residual current protection. Multiple protections enhance power reliability. After tripping, the thyristor automatically resets, and the relay coil returns to standby mode. After external faults are cleared, normal operation can be restored simply by pressing the reset button. The operation logic is clear, and maintenance costs are low.

[0029] 3. In this invention, the leakage current detection chip U3 of the main detection circuit H performs a self-test synchronously based on the bit signal collected by the leakage current detection circuit D to determine whether the leakage current detection circuit is intact, thus achieving lifespan detection. When the chip detects that its own leakage current detection function has failed or malfunctioned, pin 9 of the leakage current detection chip U3 outputs a high level, triggering the SCR to conduct, ultimately driving the main contacts to open and the protector to trip, causing the product to exit the working state. Real-time online monitoring of the protector's own leakage current detection capability allows for proactive tripping when its own function fails, indicating a fault requiring repair or replacement, thus ensuring the long-term reliability of the leakage current protection mechanism. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a circuit diagram of a leakage current protector with bidirectional leakage current detection function. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] Please see Figure 1 This invention provides a technical solution: a leakage current protector with bidirectional leakage current detection function, comprising:

[0035] The isolation module power supply A has its input circuit connected to the input side of the leakage current protector and its output circuit connected to the DC bus VCC_24V.

[0036] The input circuit of isolation module power supply B is connected to the output side of the leakage current protection device, and the output circuit is connected to the DC bus VCC_24V. Isolation module power supply A and isolation module power supply B are connected in parallel for power supply.

[0037] The main detection circuit H includes a leakage current detection chip U3, a leakage current acquisition circuit, and a neutral ground detection circuit. The leakage current acquisition circuit includes a leakage current detection magnetic ring ZCT3A, diode D10, diode D11, resistor R17, resistor R18, capacitor C11, and resistor R1. The leakage current signal acquired by the leakage current acquisition circuit is transmitted to the leakage current detection chip U3. The neutral ground detection circuit includes a neutral ground detection transformer ZCT4A, capacitor C9, capacitor C8, and resistor R20. When the neutral line output and the ground line are short-circuited, the neutral ground detection circuit generates an oscillation signal and transmits it to the leakage current detection chip U3. The RC components such as R11, R13, R16, and C7 around the leakage current detection chip U3 in the main detection circuit H are used to configure the leakage current threshold, tripping delay, and oscillation parameters.

[0038] The leakage current detection circuit D is used to collect the grid phase synchronization signal and output it to the leakage current detection chip U3. The leakage current detection circuit D provides the grid phase synchronization signal for the life self-test function of the leakage current detection chip U3, and achieves strong and weak current isolation through optocoupler.

[0039] The tripping and self-reset circuit I is used to control the energization and de-energization of the relay coil SOL2 and the reset of the silicon controlled rectifier SCR after receiving the trigger signal from the leakage current detection chip U3.

[0040] The working principle of the isolation module power supply A is as follows.

[0041] Input circuit: AC input Lin → fuse F1 (2A / 250V time-delay type) → AC input pin of U1 (AC-DC-5W isolated power supply module); Nin is directly connected to another AC input pin of U1. CX1 (10μF X-type safety capacitor) is connected in parallel between live and neutral for input EMI filtering; CY1 (1nF Y-type safety capacitor) is connected between the primary and secondary sides of U1 to suppress common-mode interference.

[0042] Output circuit: Capacitors C1, D1 (24V transient suppression diode), and C2 (470μF electrolytic capacitor) are connected in parallel at the DC output terminal of U1 to form a filter + overvoltage clamping circuit, which finally outputs a stable VCC_24V DC bus, with the negative terminal connected to system ground.

[0043] The working principle of the isolation module power supply B is as follows.

[0044] Input circuit: AC output Lout → fuse F2 (2A / 250V time delay type) → AC input pin of U2 (AC-DC-5W isolated power supply module); Nout is directly connected to another AC input pin of U2; CY2 (1nF Y-type safety capacitor) is connected between the primary and secondary sides of U2.

[0045] Output circuit: C26 ceramic capacitor and C30 electrolytic capacitor are connected in parallel to filter the DC output terminal of U2. The positive terminal of the output is connected to the VCC_24V bus, and the negative terminal is connected to the system ground.

[0046] Both isolation module power supply A and isolation module power supply B are AC to DC isolation module power supplies. Specifically, the AC to DC isolation module power supply is either a high-frequency switching type AC to DC isolation module power supply or a power frequency transformer type AC to DC isolation module power supply. Either a high-frequency switching scheme or a power frequency transformer scheme can be used for the AC to DC isolation module power supply.

[0047] The leakage current detection circuit D includes two sets of EL3H7C optocouplers, U4A and U4B. The primary side of the optocoupler is connected to the AC high-voltage circuit through a current-limiting resistor, converting the power frequency AC voltage into an isolated square wave synchronization signal. The secondary side output is sent to the leakage current detection chip U3 in the main detection circuit H as a reference for power grid zero-crossing and phase identification, supporting the timing judgment of life monitoring and self-test functions.

[0048] The tripping and self-reset circuit I includes the main coil circuit, the tripping trigger branch, and the thyristor self-reset branch.

[0049] Main circuit of the coil: Relay coil SOL2 is connected in parallel between VCC_24V and ground, D7 is a freewheeling diode, and C4 is a buffer capacitor. Under normal conditions, MOSFET Q2 is turned off, all current flows through relay coil SOL2, relay coil SOL2 is energized, and SW contacts remain closed.

[0050] Tripping trigger branch: When the leakage current detection function is normal, when a neutral ground fault occurs and the leakage current exceeds the set threshold, pin 13 of the leakage current detection chip U3 outputs a high level, triggering the SCR to conduct. Vg is applied to the gate of Q2 through the conducting SCR, and the gate of Q2 becomes high. At this time, the MOSFET Q2 is turned on, the relay coil SOL2 is de-energized, the SW contact is opened, and the leakage current protector is tripped.

[0051] The self-reset branch of the thyristor: the leakage current detection chip U3 sends an instantaneous pulse signal to drive the transistor Q1. The gate level of the MOSFET Q2 is pulled low instantaneously, turning off the MOSFET Q2. The thyristor SCR is automatically turned off and reset due to the disappearance of the anode current. The relay coil SOL2 is energized again and will maintain a continuous current, entering the waiting for manual reset state.

[0052] Manual reset logic: The SW contacts are equipped with a tripping mechanism with a mechanical latch. When the coil is de-energized, the latch releases and the contacts open. After the coil is energized again, the latch will not automatically reset. Pressing the RESET button will push the mechanical structure to reset, and the SW contacts will then close again.

[0053] A varistor is connected in parallel between the live and neutral wires on the input side of the residual current device (RCD). At point E of the surge protection circuit at the input terminal, when a lightning strike or operational surge overvoltage occurs at the input terminal, the varistor quickly conducts to discharge energy and clamp the voltage, protecting the downstream high-voltage components.

[0054] The output of the voltage regulator circuit F is connected to the analog detection power supply pin of the leakage current detection chip U3. The voltage regulator circuit F acts as the Vs power supply, stepping down and regulating the 24V DC to 5V, providing independent power to the detection section of the leakage current detection chip U3.

[0055] VCC_24V is current-limited by R6, clamped by Zener diode D5, and filtered by capacitor C10, outputting Vs 5V DC, which is connected to the analog detection power supply pin of U3 chip to power the leakage current signal acquisition and fault diagnosis circuit.

[0056] The output of the voltage regulator circuit G is connected to the drive power pin of the tripping and leakage detection chip U3. As the Vg power supply, the voltage regulator circuit G steps down and regulates the 24V DC to 5V, providing independent power to the chip's drive section and reducing interference.

[0057] VCC_24V is current-limited by R8, clamped by Zener diode D9, and filtered by C6, outputting Vg 5V DC, which is connected to the drive power supply pin of U3 chip, and at the same time provides a level reference for the gate of the MOS transistor in the trip execution and self-reset circuit I.

[0058] The main detection circuit H also includes a test circuit, which consists of a TEST button and a resistor R19. The TEST button and resistor R19 are connected in series and then connected across the live and neutral wires, passing through the leakage current detection magnetic ring ZCT3A. When the TEST button is pressed, a simulated leakage current is generated to verify the tripping function of the leakage current protector.

[0059] Working principle: When the input is powered in the forward direction, the SW contact is initially open, and the power supply of the isolation module B on the output side cannot receive input. The power supply of the relay coil SOL2 is supplied by the power supply of the isolation module A on the input side, and it supports RESET button reset. When the output is powered in the reverse direction, the SW contact is initially open, and the power supply of the isolation module A on the input side cannot receive input. The power supply of the relay coil SOL2 is supplied by the power supply of the isolation module B on the output side, and it also supports RESET button reset.

[0060] Isolation module power supply A and isolation module power supply B form a bidirectional power supply architecture. Isolation module power supply A draws power from the input side (Lin / Nin) of the residual current device (RCD) and outputs an isolated 24V DC to supply power to the system during forward power supply. Isolation module power supply B draws power from the output side (Lout / Nout) of the RCD and outputs an isolated 24V DC to supply power to the system during reverse power supply.

[0061] Both isolation module power supply A and isolation module power supply B output +24V DC voltage and are electrically isolated from each other, ensuring that the withstand voltage performance of the input and output terminals meets regulatory requirements under tripping conditions. Regardless of whether the input terminal is energized in the forward direction or the output terminal is energized in the reverse direction, the relay can be powered through the corresponding isolated power supply to achieve reset and normal protection operation, overcoming the limitation of unidirectional leakage current protectors failing to operate under reverse power. The leakage current protector will not conduct directly under reverse power, avoiding the risk of accidental energization caused by reverse power supply after power failure.

[0062] The leakage current detection chip U3 in the main detection circuit H performs a self-test synchronously based on the bit signal collected by the leakage current detection circuit D to determine whether the leakage current detection circuit is intact, thus achieving lifespan detection. When the chip detects a failure or malfunction in its own leakage current detection function, pin 9 of the leakage current detection chip U3 outputs a high level, triggering the SCR to conduct, ultimately driving the main contacts to open and the protector to trip, causing the product to exit the working state. Real-time online monitoring of the protector's own leakage current detection capability allows for proactive tripping when its own function fails, indicating a fault requiring repair or replacement, thus ensuring the long-term reliability of the leakage current protection mechanism.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A residual current device (RCD) with bidirectional leakage current detection function, characterized in that, include: The isolation module power supply A has its input circuit connected to the input side of the leakage current protector and its output circuit connected to the DC bus VCC_24V. The isolation module power supply B has its input circuit connected to the output side of the leakage current protector and its output circuit connected to the DC bus VCC_24V. The isolation module power supply A and the isolation module power supply B are connected in parallel for power supply. The main detection circuit H includes a leakage current detection chip U3, a leakage current acquisition circuit, and a neutral ground detection circuit. The leakage current acquisition circuit includes a leakage current detection magnetic ring ZCT3A, a diode D10, a diode D11, a resistor R17, a resistor R18, a capacitor C11, and a resistor R1. The leakage current signal acquired by the leakage current acquisition circuit is transmitted to the leakage current detection chip U3. The neutral ground detection circuit includes a neutral ground detection transformer ZCT4A, a capacitor C9, a capacitor C8, and a resistor R20. When the neutral line output and the ground line are short-circuited, the neutral ground detection circuit generates an oscillation signal and transmits it to the leakage current detection chip U3. The leakage current detection circuit D is used to collect the power grid phase synchronization signal and output it to the leakage current detection chip U3. The tripping and self-reset circuit I is used to control the energization and de-energization of the relay coil SOL2 and the reset of the silicon controlled rectifier SCR after receiving the trigger signal from the leakage current detection chip U3.

2. A residual current device (RCD) with bidirectional leakage current detection function according to claim 1, characterized in that, Both the isolation module power supply A and the isolation module power supply B are AC to DC isolation module power supplies.

3. A residual current device (RCD) with bidirectional leakage current detection function according to claim 2, characterized in that, The AC to DC isolation module power supply is a high-frequency switching AC to DC isolation module power supply or a power frequency transformer type AC to DC isolation module power supply.

4. A residual current device (RCD) with bidirectional leakage current detection function according to claim 1, characterized in that, A varistor is connected in parallel between the live wire and the neutral wire on the input side of the residual current device (RCD).

5. A residual current device (RCD) with bidirectional leakage current detection function according to claim 1, characterized in that, The output of the voltage regulator circuit F is connected to the analog detection power supply pin of the leakage current detection chip U3.

6. A residual current device (RCD) with bidirectional leakage current detection function according to claim 1, characterized in that, The output of the voltage regulator circuit G is connected to the drive power pin of the leakage current detection chip U3.

7. A residual current device (RCD) with bidirectional leakage current detection function according to claim 1, characterized in that, The main detection circuit H also includes a test circuit, which includes a TEST button and a resistor R19. The TEST button and the resistor R19 are connected in series and then connected across the live and neutral wires, and pass through the leakage current detection magnetic ring ZCT3A.

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