Current detection circuit for electricity meters and electricity meters

Abstract

This application discloses a current detection circuit for an electricity meter and an electricity meter itself. The circuit includes: a grid current detection module, a switch module, and a power-off current detection module. The grid current detection module is connected to the power grid and is used to detect the current in the grid and output a detection signal. The switch module is connected to both the grid current detection module and the power-off current detection module, and is used to connect the grid current detection module to the power-off current detection module when the electricity meter is in a power-off state. The power-off current detection module is connected to the switch module and is used to determine whether current flows through the grid based on the detection signal after the electricity meter is powered off. This application realizes grid current detection after the electricity meter is powered off, which can effectively reflect the actual electricity consumption of the grid, thereby preventing electricity theft and other similar situations.

Description

Technical Field

[0001] This application belongs to the field of circuit technology, specifically relating to a current detection circuit for an electricity meter and an electricity meter. Background Technology

[0002] An electricity meter, also known as a kilowatt-hour meter or energy meter, is an instrument used to measure electrical energy. Connected to the power grid, the meter calculates the user's electricity consumption by detecting relevant parameters when the user uses electricity. However, in some cases, the electricity meter may experience a power outage. When power is lost, the meter cannot calculate electricity correctly, making it impossible to determine whether the user has used electricity from the grid. Therefore, detecting electricity consumption when the meter is powered off is a pressing issue that needs to be addressed.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide a current detection circuit for an electricity meter, so as to optimize the problem that electricity meters are difficult to detect electricity consumption under power failure conditions in related technologies.

[0005] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0006] According to one aspect of the embodiments of this application, a current detection circuit for an electricity meter is provided, including: a grid current detection module, a switch module, and a power failure current detection module;

[0007] The power grid current detection module is connected to the power grid and is used to detect the current in the power grid and output a detection signal.

[0008] The switching module is connected to the grid current detection module and the power failure current detection module respectively, and is used to connect the grid current detection module to the power failure current detection module when the energy meter is in a power failure state.

[0009] The power failure current detection module is connected to the switch module and is used to determine whether there is current flowing through the power grid based on the detection signal after the power meter loses power.

[0010] In one embodiment of this application, the switch module includes a normally open terminal, a common terminal, and a control terminal. The normally open terminal is connected to the grid current detection module, and the common terminal is connected to the power failure current detection module. The control terminal is used to control the connection between the common terminal and the normally open terminal according to the power failure signal of the electricity meter, wherein the power failure signal of the electricity meter indicates that the electricity meter is in a power failure state.

[0011] In one embodiment of this application, the switch module further includes a normally closed terminal, which is grounded, and the control terminal is further configured to control the connection between the common terminal and the normally closed terminal according to the power-on signal of the energy meter, wherein the power-on signal of the energy meter indicates that the energy meter is in a powered-on state.

[0012] In one embodiment of this application, the power grid current detection module includes a current sensing unit and a sampling unit;

[0013] The current sensing unit is connected to the power grid and is used to detect the current in the power grid and generate a current sensing signal.

[0014] The sampling unit is connected to the current sensing unit and is used to generate the detection signal based on the current sensing signal.

[0015] In one embodiment of this application, the sampling unit includes a first sampling resistor and a second sampling resistor;

[0016] One end of the first sampling resistor is connected to the first output terminal of the current sensing unit, and the other end is grounded;

[0017] One end of the second sampling resistor is connected to the second output terminal of the current sensing unit, and the other end is grounded.

[0018] In one embodiment of this application, the power-down current detection module includes an amplification unit, a shaping unit, and a control unit;

[0019] The amplification unit is connected to the switching module and is used to amplify the detection signal and output an amplified signal.

[0020] The shaping unit and the amplification unit are used to shape the amplified signal and output the shaped signal;

[0021] The control unit is connected to the shaping unit and is used to determine that there is current flowing through the power grid when the shaping signal is received.

[0022] In one embodiment of this application, the control unit is further connected to the switch module, and the control unit is further configured to detect the state of the electricity meter, and send a power-off signal or a power-on signal of the electricity meter to the switch module according to the detection result; wherein, the power-off signal of the electricity meter indicates that the electricity meter is in a power-off state; the power-on signal of the electricity meter indicates that the electricity meter is in a power-on state, and the power-on signal of the electricity meter is used to control the switch module to ground the power-off current detection module.

[0023] In one embodiment of this application, the current detection circuit for the electricity meter further includes a power-on current detection module, which is connected to the grid current detection module and is used to calculate the current signal flowing through the grid based on the detection signal when the electricity meter is in a power-on state.

[0024] In one embodiment of this application, the power-on current detection module includes a filtering unit and a metering unit;

[0025] The filtering unit is connected to the power grid current detection module and is used to filter the detection signal and output a filtered signal.

[0026] The metering unit is connected to the filtering unit and is used to calculate the current signal flowing through the power grid based on the filtered signal.

[0027] According to one aspect of the embodiments of this application, an electricity meter is provided, the electricity meter including a current detection circuit for an electricity meter provided in any embodiment of this application.

[0028] In the technical solution provided in this application embodiment, the current detection circuit for an electricity meter includes a grid current detection module, a switch module, and a power outage current detection module. The grid current detection module is connected to the power grid and can detect the grid current and output a detection signal. After the electricity meter loses power, the switch module connects the grid current detection module to the power outage current detection module, so that the power outage current detection module determines whether there is current flowing through the grid based on the detection signal. This realizes the detection of grid current after the electricity meter loses power, which can effectively reflect the actual electricity consumption of the grid and thus prevent electricity theft.

[0029] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0031] Figure 1 A schematic block diagram of a current detection circuit for an electricity meter provided in one embodiment of this application is shown.

[0032] Figure 2 A schematic block diagram of a current detection circuit for an electricity meter provided in one embodiment of this application is shown.

[0033] Figure 3 A schematic block diagram of a current detection circuit for an electricity meter provided in one embodiment of this application is shown.

[0034] Figure 4 A schematic diagram of a current detection circuit for an electricity meter provided in one embodiment of this application is shown.

[0035] Figure 5 A schematic diagram illustrating an application scenario of the technical solution of this application is shown.

[0036] Figure 6 A schematic diagram illustrating an application scenario of the technical solution of this application is shown. Detailed Implementation

[0037] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0038] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other components, steps, etc., may be employed. In other instances, well-known practices, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0039] Figure 1 A schematic block diagram of a current detection circuit for an electricity meter provided in one embodiment of this application is shown.

[0040] like Figure 1 As shown, the current detection circuit 100 for an electricity meter includes a grid current detection module 200, a switch module 300, and a power failure current detection module 400. The grid current detection module 200 is connected to the power grid, and the switch module 300 is connected between the grid current detection module 200 and the power failure current detection module 400.

[0041] The power grid current detection module 200 is used to detect current in the power grid and output a detection signal. The detection signal output by the power grid current detection module 200 can indicate whether current is flowing through the power grid. Further calculations on the detection signal can also determine the magnitude of the current flowing through the power grid.

[0042] Under normal circumstances, that is, when the electricity meter is powered on, the detection signal output by the grid current detection module 200 is calculated by the electricity meter's energy measurement module to obtain the magnitude of the current flowing through the grid. The electricity meter being powered on means that the internal components of the electricity meter can operate normally under the drive of the operating voltage, thus enabling the relevant calculations to be performed on the detection signal.

[0043] When an electricity meter is in a power-off state, its internal components cannot connect to the operating voltage, and therefore cannot function properly to perform relevant calculations on the detection signals. If the power grid is still outputting electricity at this time, a traditional electricity meter, due to the malfunctioning components, will be unable to detect whether current is flowing through the power grid, and thus cannot determine whether the power grid's energy has been used.

[0044] In this embodiment, when the electricity meter is in a power-off state, the switch module 300 connects the current detection module and the power-off current detection module 400, that is, the detection signal output by the grid current detection module 200 is transmitted to the power-off current detection module 400, so that the power-off current detection module 400 can determine whether there is current flowing in the grid through the detection signal. In this way, the current detection of the electricity meter after power failure is realized.

[0045] In one embodiment of this application, the current detection circuit 100 for the electricity meter further includes a battery, and the power-off current detection module 400 is connected to the battery. When the electricity meter is in a power-off state, the battery provides the operating voltage to the power-off current detection module 400.

[0046] In one embodiment of this application, the switch module 300 and the power failure current detection module 400 adopt a low-power design, that is, the power consumed by the switch module 300 and the power failure current detection module 400 is low, thereby ensuring that the switch module 300 and the power failure current detection module 400 can effectively detect the current for a long time after the power meter is lost.

[0047] In the technical solution provided in this application embodiment, the current detection circuit for an electricity meter includes a grid current detection module, a switch module, and a power outage current detection module. The grid current detection module is connected to the power grid and can detect the grid current and output a detection signal. After the electricity meter loses power, the switch module connects the grid current detection module to the power outage current detection module, so that the power outage current detection module determines whether there is current flowing through the grid based on the detection signal. This realizes the detection of grid current after the electricity meter loses power, which can effectively reflect the actual electricity consumption of the grid and thus prevent electricity theft.

[0048] Figure 2 A schematic block diagram of a current detection circuit for an electricity meter according to one embodiment of this application is shown. This embodiment is a further refinement of the above embodiment.

[0049] like Figure 2 As shown, the current detection circuit 100 for an electricity meter provided in this application embodiment includes a grid current detection module 200, a switch module 300, and a power failure current detection module 400.

[0050] The switch module 300 includes a normally open terminal 310, a common terminal 320, and a control terminal 330. The normally open terminal 310 is connected to the current detection module, and the common terminal 320 is connected to the power-down current detection module 400. The control terminal 330 is used to control the connection and disconnection between the common terminal 320 and the normally open terminal 310 according to a control signal. When the energy meter is in a power-down state, the control terminal 330 receives a power-down signal from the energy meter and connects the common terminal 320 to the normally open terminal 310 according to the power-down signal, thereby connecting the current detection module to the power-down current detection module 400.

[0051] Furthermore, such as Figure 2 As shown, the switch module 300 also includes a normally closed terminal 340, which is grounded. When the energy meter is in a normal power-on state, the control terminal 330 receives the energy meter power-on signal. The control terminal 330 controls the common terminal 320 of the switch module 300 to connect to the normally closed terminal 340 according to the energy meter power-on signal, that is, to ground the power-off current detection module 400, thereby preventing the power-off current detection module 400 from affecting the energy measurement in the normal power-on state of the energy meter, and avoiding affecting the measurement accuracy of the energy meter in the normal power-on state.

[0052] Furthermore, such as Figure 2 As shown in the embodiment of this application, the current detection circuit 100 for an electricity meter also includes a power-on current detection module 500. The power-on current detection module 500 is mainly used for detecting the grid current when the electricity meter is powered on. It is connected to the current detection module, receives the detection signal output by the current detection module, and calculates the current signal flowing through the grid based on the detection signal.

[0053] The working principle of the technical solution provided in this application embodiment is as follows: when the electricity meter is in the power-on state, the power-off current detection module 400 is grounded, and the grid current is detected by the power-on current detection module 500. When the electricity meter is in the power-off state, the power-on current detection module 500 cannot work normally, and the switch module 300 connects the current detection module to the power-off current detection module 400 based on the electricity meter power-off signal, thereby realizing the detection of the grid current through the power-off current detection module 400.

[0054] Figure 3 A schematic block diagram of a current detection circuit for an electricity meter provided in one embodiment of this application is shown. This embodiment is a further refinement of the above embodiment.

[0055] like Figure 3 As shown, the current detection circuit 100 for an electricity meter provided in this application embodiment includes a grid current detection module 200, a switch module 300, a power-off current detection module 400, and a power-on current detection module 500. The specific structure of the switch module 300 is the same as that in the above embodiment, and will not be described again here.

[0056] The power grid current detection module 200 includes a current sensing unit 210 and a sampling unit 220. The current sensing unit 210 is connected to the power grid, and the sampling unit 220 is connected to the current sensing unit 210. The current sensing unit 210 detects the current in the power grid and generates a current sensing signal, which reflects the magnitude of the power grid current and is positively correlated with it. The current sensing signal is input to the sampling unit 220 to generate a detection signal.

[0057] The power failure current detection module 400 includes an amplification unit 410, a shaping unit 420, and a control unit 430, which are connected sequentially. The amplification unit 410 is also connected to the switch module 300. When the energy meter is in a power failure state, the switch module 300 connects the amplification unit 410 to the sampling unit 220, allowing the detection signal to be input to the amplification unit 410. The amplification unit 410 amplifies the detection signal to obtain an amplified signal. This amplification facilitates subsequent signal acquisition and calculation. The amplified signal is then input to the shaping unit 420, which shapes the amplified signal to obtain a shaped signal. Shaping involves modifying the waveform of the amplified signal to obtain a more regular waveform. When the control unit 430 receives the shaped signal, it can determine that current is flowing through the power grid. The control unit 430 can record the duration of the received shaped signal, which reflects the duration of power consumption after the energy meter is powered off.

[0058] The power-on current detection module 500 includes a filtering unit 510 and a metering unit 520. The filtering unit 510 is connected to the grid current detection module 200, and the metering unit 520 is connected to the filtering unit 510. When the energy meter is powered on, the filtering unit 510 filters the detection signal output by the grid current detection module 200 and outputs a filtered signal. This filtering process is an anti-aliasing filter, which reduces aliasing components in the detection signal to improve the metering accuracy of the energy meter. The metering unit 520 calculates the current signal flowing through the grid based on the filtered signal.

[0059] Figure 4 The diagram illustrates a structural diagram of a current detection circuit for an electricity meter according to one embodiment of this application. This embodiment is a further refinement of the above embodiment.

[0060] like Figure 4 As shown, the current detection circuit 100 for an electricity meter provided in this application embodiment includes a grid current detection module 200, a switch module 300, a power-off current detection module 400, and a power-on current detection module 500.

[0061] The power grid current detection module 200 includes a current sensing unit 210 and a sampling unit 220. The current sensing unit 210 is a current sensor CT. The primary winding of the current sensor CT is connected to the power line of the power grid, and the secondary winding of the current sensor CT includes a first output terminal and a second output terminal, which are respectively connected to the sampling unit 220.

[0062] The sampling unit 220 includes a first sampling resistor R1 and a second sampling resistor R2. One end of the first sampling resistor R1 is connected to the first output terminal of the current sensor CT, and the other end is grounded. One end of the second sampling resistor R2 is connected to the second output terminal of the current sensor CT, and the other end is grounded. For ease of description, the common terminal 320 of the first sampling resistor R1 and the current sensor CT is denoted as the first node T1, and the common terminal 320 of the second sampling resistor R2 and the current sensor CT is denoted as the second node T2.

[0063] The power-on current detection module 500 includes a filtering unit 510 and a metering unit 520. The filtering unit 510 includes a first filtering resistor R3, a second filtering resistor R4, a first filtering capacitor C1, and a second filtering capacitor C2. One end of the first filtering resistor R3 is connected to a first node T1, and the other end is connected to one end of the first filtering capacitor C1, with the other end of the first filtering capacitor C1 grounded. One end of the second filtering resistor R4 is connected to a second node T2, and the other end is connected to one end of the second filtering capacitor C2, with the other end of the second filtering capacitor C2 grounded. The metering unit 520 is a metering chip 521.

[0064] The switch module 300 includes a normally open terminal 310, a normally closed terminal 340, a common terminal 320, and a control terminal 330. The normally open terminal 310 includes a first normally open interface NO1 and a second normally open interface NO2. The first normally open interface NO1 is connected to a first node T1, and the second normally open interface NO2 is connected to a second node T2. The normally closed terminal 340 includes a first normally closed interface NC1 and a second normally closed interface NC2, both of which are grounded. The common terminal 320 includes a first common interface COM1 and a second common interface COM2. The control terminal 330 connects the common terminal 320 to either the normally open terminal 310 or the normally closed terminal 340 according to a control signal.

[0065] The power-down current detection module 400 includes an amplification unit 410, a shaping unit 420, and a control unit 430. The amplification unit 410 includes an amplifier OP1, a first resistor R5, a second resistor R7, a third resistor R8, and a fourth resistor R6. One end of the first resistor R5 is connected to the first common interface COM1 of the switch module 300, and the other end is connected to the first input terminal of the amplifier OP1. One end of the second resistor R7 is connected to the second common interface COM2 of the switch module 300, and the other end is connected to the second input terminal of the amplifier OP1. The third resistor R8 is connected between the first input terminal and the output terminal of the amplifier OP1. One end of the fourth resistor R6 is connected to the second input terminal of the amplifier OP1, and the other end is grounded. The amplifier OP1 also includes a power supply terminal for connecting the operating power supply and a grounded terminal. When the energy meter is powered on, the power supply terminal of the amplifier OP1 is connected to the power supply that powers the energy meter; when the energy meter is powered off, the power supply terminal of the amplifier OP1 is connected to the built-in battery of the energy meter; that is, the operating power supply is the battery.

[0066] The shaping unit 420 includes a comparator OP2, a fifth resistor R9, a sixth resistor R10, and a seventh resistor R11. The first input terminal of comparator OP2 is connected to the output terminal of amplifier OP1. The second input terminal of comparator OP2 is connected to one end of the fifth resistor R9, and the other end of the fifth resistor R9 is connected to the operating power supply. One end of the sixth resistor R10 is connected to the second input terminal of comparator OP2, and the other end is grounded. One end of the seventh resistor R11 is connected to the output terminal of comparator OP2, and the other end is connected to the operating power supply. Comparator OP2 also includes a power supply terminal connected to the operating power supply and a ground terminal. The configuration of the operating power supply in the shaping unit 420 is the same as that in the amplification unit 410, and will not be described again here.

[0067] In one embodiment of this application, the first and second input terminals of comparator OP2 in the shaping unit 420 can be reversed, that is, the second input terminal of comparator OP2 is connected to the output terminal of amplifier OP1, and the first input terminal of comparator OP2 is connected to the fifth resistor R9. The reversal of the first and second input terminals of comparator OP2 only affects the direction of the signal output by comparator OP2 (i.e., the positive or negative sign of the signal), and does not affect the amplitude of the output signal (i.e., the magnitude of the signal value).

[0068] The control unit 430 is an MCU (Microcontroller Unit), which is connected to the output of comparator OP2, the metering chip 521, and the control terminal 330 of the switch module 300. The metering chip 521 can communicate with the MCU, sending its own data to the MCU for further calculation or use.

[0069] When the MCU detects that the energy meter is powered on, it generates an energy meter power-on signal and sends the energy meter power-on signal to the control terminal 330 of the switch module 300. This causes the switch module 300 to connect the common terminal 320 to the normally closed terminal 340, which means that the power-down current detection module 400 is grounded, thus preventing the power-down current detection module 400 from affecting the detection accuracy of the power-on current detection module 500.

[0070] When the MCU detects that the energy meter is in a power-off state, it generates an energy meter power-off signal and sends the energy meter power-off signal to the control terminal 330 of the switch module 300. This causes the switch module 300 to connect the common terminal 320 with the normally open terminal 310, which in turn connects the power-off current detection module 400 with the grid current detection module 200, enabling the power-off current detection module 400 to start working and determine whether there is current flowing through the grid.

[0071] When the electricity meter is powered on, the power-off current detection module 400 is grounded and does not detect the grid current; instead, the power-on current detection module 500 operates normally. When current flows through the power line, the secondary winding of the current sensor CT generates a current sensing signal. Since the sampling unit 220 and the secondary winding of the current sensor CT form a loop, the current sensing signal generates a voltage signal across the resistor of the sampling unit 220, forming a voltage detection signal between the first node T1 and the second node T2. This voltage detection signal is then filtered by the anti-aliasing filter unit 510 and input to the metering chip 521, which calculates the grid current.

[0072] When the electricity meter is in a power-off state, the power-on current detection module 500 cannot function properly, and the power-off current detection module 400 is connected to the grid current detection module 200 to detect the grid current. When current flows through the power line, the secondary winding of the current sensor CT generates a current sensing signal. Since the sampling unit 220 and the secondary winding of the current sensor CT form a loop, the current sensing signal forms a voltage signal across the resistor of the sampling unit 220, forming a voltage detection signal between the first node T1 and the second node T2. This voltage detection signal is transmitted to both ends of the amplification unit 410 via the switching module 300, where it is amplified to generate an amplified signal. Then, the shaping unit 420 shapes the amplified signal and outputs the shaped signal to the MCU. This shaped signal can be a square wave signal. When the MCU detects the shaped signal, it determines that current is flowing through the power line, indicating that a user is using electricity.

[0073] When the electricity meter is de-energized, if no current flows through the power line, the detection signal output by the grid current detection circuit will be 0, and the shaping signal output by the shaping unit 420 will remain unchanged, for example, continuously high or continuously low. When the MCU detects this unchanging shaping signal, it determines that no current flows through the power line.

[0074] It is understandable that when the electricity meter is powered on, the power failure current detection module 400 is grounded, which is equivalent to the signal received by the power failure current detection module 400 being 0. At this time, the output of the shaping unit 420 is the same as when the electricity meter is powered off and no current flows through the power line, that is, it remains unchanged, such as a continuous high level or a continuous low level.

[0075] In the technical solution provided in this application embodiment, when the electricity meter loses power, the power-on current detection module 500 is switched to the power-off current detection module 400, realizing the detection of the grid current after the electricity meter loses power, which can effectively prevent electricity theft. At the same time, the power-off current detection module 400 has a simple circuit structure, small size, low power consumption, low manufacturing difficulty, and is easy to implement.

[0076] Figure 4 The current detection circuit shown for an electricity meter enables the detection of single-phase current, namely the detection of the current in the live wire (L-line).

[0077] Figure 5 A schematic diagram illustrating an application scenario of the technical solution of this application is shown. For example... Figure 5 As shown, the current detection circuit 100 for an electricity meter provided in this application embodiment is connected to the live wire (L line) and neutral wire (N line) of the power grid, respectively, realizing the detection of two current loops, the live wire and the neutral wire. The current detection circuit 100 for the electricity meter connected to the live wire and the neutral wire can share a single MCU.

[0078] Figure 6 A schematic diagram illustrating an application scenario of the technical solution of this application is shown. Figure 6 The diagram shows a three-phase four-wire current detection circuit, with the current detection circuit 100 for an energy meter provided in this application connected to each power line. Each detection circuit shares a single MCU.

[0079] This application also provides an electricity meter, which includes a current detection circuit 100 for an electricity meter provided in any embodiment of this application. The structure of the detection circuit can be referred to the description of the foregoing embodiments, and will not be repeated here.

[0080] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0081] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A current detection circuit for an electricity meter, characterized in that, include: Grid current detection module, switch module and power failure current detection module; The power grid current detection module is connected to the power grid and is used to detect the current in the power grid and output a detection signal. The switching module is connected to the grid current detection module and the power failure current detection module respectively, and is used to connect the grid current detection module to the power failure current detection module when the energy meter is in a power failure state. The power failure current detection module is connected to the switch module and is used to determine whether there is current flowing through the power grid based on the detection signal after the power meter loses power. The switch module includes a normally open terminal, a common terminal, and a control terminal. The normally open terminal is connected to the grid current detection module, and the common terminal is connected to the power failure current detection module. The control terminal is used to control the connection between the common terminal and the normally open terminal according to the power failure signal of the electricity meter. The power failure signal of the electricity meter indicates that the electricity meter is in a power failure state.

2. The current detection circuit for an electricity meter according to claim 1, characterized in that, The switch module also includes a normally closed terminal, which is grounded. The control terminal is also used to control the connection between the common terminal and the normally closed terminal according to the power-on signal of the energy meter. The power-on signal of the energy meter indicates that the energy meter is in a powered-on state.

3. The current detection circuit for an electricity meter according to claim 1, characterized in that, The power grid current detection module includes a current sensing unit and a sampling unit; The current sensing unit is connected to the power grid and is used to detect the current in the power grid and generate a current sensing signal. The sampling unit is connected to the current sensing unit and is used to generate the detection signal based on the current sensing signal.

4. The current detection circuit for an electricity meter according to claim 3, characterized in that, The sampling unit includes a first sampling resistor and a second sampling resistor; One end of the first sampling resistor is connected to the first output terminal of the current sensing unit, and the other end is grounded; One end of the second sampling resistor is connected to the second output terminal of the current sensing unit, and the other end is grounded.

5. The current detection circuit for an electricity meter according to claim 1, characterized in that, The power-down current detection module includes an amplification unit, a shaping unit, and a control unit; The amplification unit is connected to the switching module and is used to amplify the detection signal and output an amplified signal. The shaping unit and the amplification unit are used to shape the amplified signal and output the shaped signal; The control unit is connected to the shaping unit and is used to determine that there is current flowing through the power grid when the shaping signal is received.

6. The current detection circuit for an electricity meter according to claim 5, characterized in that, The control unit is also connected to the switch module. The control unit is also used to detect the status of the electricity meter and send a power-off signal or a power-on signal to the switch module according to the detection result. The power-off signal indicates that the electricity meter is in a power-off state. The power-on signal indicates that the electricity meter is in a power-on state. The power-on signal is used to control the switch module to ground the power-off current detection module.

7. The current detection circuit for an electricity meter according to any one of claims 1-6, characterized in that, The current detection circuit for the electricity meter also includes a power-on current detection module, which is connected to the grid current detection module and is used to calculate the current signal flowing through the grid based on the detection signal when the electricity meter is powered on.

8. The current detection circuit for an electricity meter according to claim 7, characterized in that, The power-on current detection module includes a filtering unit and a metering unit; The filtering unit is connected to the power grid current detection module and is used to filter the detection signal and output a filtered signal. The metering unit is connected to the filtering unit and is used to calculate the current signal flowing through the power grid based on the filtered signal.

9. An electricity meter, characterized in that, The electricity meter includes a current detection circuit for an electricity meter as described in any one of claims 1-8.

Images