Sampling circuit and metering circuit

Abstract

The application discloses a sampling circuit and a metering circuit. The sampling circuit comprises a voltage division module, a voltage follower module and a differential amplification module. The voltage follower module is used for voltage following of an initial voltage of a zero line and an initial voltage of a fire line. The influence of load fluctuation of a later-stage circuit on generated target voltages of the zero line and the fire line can be reduced. The differential amplification module is used for differential amplification of the target voltage of the zero line and target voltages of each fire line, so as to generate corresponding phase sampling voltages. Fluctuation of each phase voltage caused by high resistance of the zero line can be eliminated, so that stable and smooth phase sampling voltages are obtained, and the sampling precision is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a sampling circuit and a metering circuit. Background Technology

[0002] With the rapid development of the new energy industry, the demand for energy gateway products is also constantly evolving. In energy gateways with metering functions, the sampling circuit often uses a resistor to divide the voltage of the live wire and the neutral wire. This creates a high-resistance solution between the neutral wire and the metering unit, which reduces the risk of electric shock when a person touches the metering unit and its downstream circuitry.

[0003] However, due to load fluctuations in the subsequent circuits and / or the high impedance of the neutral line, the phase sampling voltage generated by the sampling circuit is prone to fluctuations, resulting in a decrease in sampling accuracy. Utility Model Content

[0004] This application provides a sampling circuit and a metering circuit to alleviate the technical problem of low sampling accuracy.

[0005] In a first aspect, this application provides a sampling circuit, which includes a voltage divider module, a voltage follower module, and a differential amplifier module. The voltage divider module is connected to a neutral line and at least one live line, and is configured to divide the voltage of the neutral line and the voltage of the live line respectively to generate corresponding initial voltages for the neutral line and the live line. The voltage follower module is connected to the voltage divider module and is configured to follow the initial voltages of the neutral line and the live line respectively to generate corresponding target voltages for the neutral line and the live line. The differential amplifier module is connected to the voltage follower module and is configured to differentially amplify the target voltage of the neutral line and each target voltage of the live line respectively to generate corresponding phase sampling voltages.

[0006] Secondly, this application also provides a metering circuit, which includes the above-mentioned sampling circuit and metering module. The metering module is connected to the output terminal of the differential amplifier module and is configured to perform metering based on the phase sampling voltage.

[0007] The sampling and metering circuits provided in this application use a voltage follower module to follow the initial voltage of the neutral wire and the initial voltage of the live wire. This reduces the impact of load fluctuations in the subsequent circuits on the generated target voltages of the neutral wire and the live wire. The differential amplification module differentially amplifies the target voltage of the neutral wire and each target voltage of the live wire to generate the corresponding phase sampling voltage. This eliminates the fluctuations in the phase voltages introduced by the high resistance of the neutral wire, thereby obtaining a stable and smooth phase sampling voltage and improving the sampling accuracy. Attached Figure Description

[0008] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 This is a schematic block diagram of the sampling circuit provided in an embodiment of this application.

[0010] Figure 2 The first circuit schematic diagram of the sampling circuit provided in the embodiments of this application.

[0011] Figure 3 The second circuit schematic diagram of the sampling circuit provided in the embodiments of this application.

[0012] Figure 4 The circuit schematic diagram of the power supply module of the sampling circuit provided in the embodiment of this application.

[0013] Figure 5 This is a schematic diagram of the metering circuit provided in an embodiment of this application. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0015] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Features thus defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more unless otherwise explicitly specified.

[0016] With the rapid development of the new energy industry, the demand for energy gateway products is also constantly evolving. In the past, the circuit part of energy gateways with metering functions often used resistors to divide the voltage of the live wire, converting the mains power into a small voltage signal that could be processed by a microcontroller, and then the metering unit measured the voltage signal.

[0017] This method typically employs a neutral wire grounding design, which uses the neutral wire as the reference for voltage sampling. The voltage on the actual power line can be directly calculated through the voltage divider resistors to achieve the purpose of voltage sampling.

[0018] In this design, the neutral wire is directly connected to the metering unit at the next stage. The mains power and the metering unit do not form a high-impedance circuit, and there is no electrical isolation required by safety regulations, which poses certain safety hazards to the human body.

[0019] Furthermore, adding isolation devices between the metering unit and the microcontroller unit (MCU) increases both product cost and size, thus reducing the product's competitiveness in the market.

[0020] Designing a high-resistance neutral wire scheme can effectively avoid the aforementioned design drawbacks. This scheme involves inserting a large resistor (high resistance) in series between the neutral wire and the metering reference point (GND). The sampled signal is then processed by an operational amplifier before being measured by the metering unit. Because of the high resistance between the neutral wire and the metering unit, the risk of electric shock when a person touches the metering unit and its subsequent circuitry is reduced. Furthermore, no other isolation devices are required, achieving the design goals of low cost and miniaturization.

[0021] like Figure 1 As shown, this embodiment provides a sampling circuit 100, which includes a voltage divider module 10, a voltage follower module 20, and a differential amplifier module 30. The voltage divider module 10 is connected to the neutral line N and at least one live line. The voltage divider module 10 is configured to divide the voltage of the neutral line N and the voltage of the live line respectively to generate corresponding initial voltages for the neutral line and live line. The voltage follower module 20 is connected to the voltage divider module 10 and is configured to follow the initial voltages of the neutral line and live line to generate corresponding target voltages for the neutral line and live line respectively. The differential amplifier module 30 is connected to the voltage follower module 20 and is configured to differentially amplify the target voltage of the neutral line and each target voltage of the live line to generate corresponding phase sampling voltages.

[0022] It is understood that the sampling circuit 100 provided in this embodiment uses the voltage follower module 20 to perform voltage following on the initial voltage of the neutral line and the initial voltage of the live line, which can reduce the influence of load fluctuations in the subsequent circuits on the generated target voltages of the neutral line and the live line. The differential amplification module 30 performs differential amplification on the target voltage of the neutral line and each target voltage of the live line to generate the corresponding phase sampling voltage, which can eliminate the fluctuations of each phase voltage introduced by the high resistance of the neutral line N, thereby obtaining a stable and smooth phase sampling voltage, and thus improving the sampling accuracy.

[0023] It should be noted that the number of live wires can be an integer such as 1, 2, or 3, corresponding one-to-one with the number of phase sampling voltages.

[0024] In some embodiments, such as Figure 2As shown, at least one live wire includes a first live wire A, a second live wire B, and a third live wire C. The voltage divider module 10 includes a first voltage divider unit 11, a second voltage divider unit 12, a third voltage divider unit 13, and a fourth voltage divider unit 14. The first voltage divider unit 11 is connected to the first live wire A and the first input terminal of the voltage follower module 20; the second voltage divider unit 12 is connected to the second live wire B and the second input terminal of the voltage follower module 20; the third voltage divider unit 13 is connected to the third live wire C and the third input terminal of the voltage follower module 20; and the fourth voltage divider unit 14 is connected to the neutral wire N and the fourth input terminal of the voltage follower module 20.

[0025] It should be noted that this application uses voltage sampling of a three-phase four-wire power grid as an example for illustration. The first voltage divider unit 11 can divide the voltage of the first live wire A to obtain a first initial voltage. The second voltage divider unit 12 can divide the voltage of the second live wire B to obtain a second initial voltage. The third voltage divider unit 13 can divide the voltage of the third live wire C to obtain a third initial voltage. The fourth voltage divider unit 14 can divide the voltage of the neutral wire N to obtain the initial neutral wire voltage.

[0026] The fourth voltage divider unit 14 enables a high-resistance scheme between the neutral wire N and the subsequent metering module 210, thereby avoiding the risk of electric shock to the human body.

[0027] In some embodiments, such as Figure 2 As shown, the first voltage divider unit 11 includes multiple first resistors and second resistors R14. The multiple first resistors are connected in series between the first live wire A and the first input terminal of the voltage follower module 20. The first end of the second resistor R14 is connected to the first input terminal of the voltage follower module 20 and the first resistors, and the second end of the second resistor R14 is connected to the ground terminal GND. The resistance value of the first resistor is greater than the resistance value of the second resistor R14.

[0028] It should be noted that the plurality of first resistors can be at least two of R114, R115, R116, R117, R118, R119, and R120. In other embodiments of this application, the first voltage divider unit 11 includes seven first resistors. The resistance value of each first resistor can be, but is not limited to, the same value, or different values. The resistance value of the first resistor can be in the megaohm range (MΩ), and the resistance value of the second resistor R14 can be in the kiloohm range (KΩ). For example, the resistance value of the first resistor can be 1MΩ, and the resistance value of the second resistor R14 can be 3KΩ. This is beneficial for obtaining a voltage signal suitable for processing by the operational amplifier in the voltage follower module 20.

[0029] In some embodiments, such as Figure 2As shown, the second voltage divider unit 12 includes multiple third resistors and a fourth resistor R13. The multiple third resistors are connected in series between the second live wire B and the second input terminal of the voltage follower module 20. The first end of the fourth resistor R13 is connected to the second input terminal of the voltage follower module 20 and the third resistors, and the second end of the fourth resistor R13 is connected to the ground terminal GND. The resistance value of the third resistor is greater than the resistance value of the fourth resistor R13.

[0030] It should be noted that the multiple third resistors can be at least two of R121, R122, R123, R124, R125, R126, and R127. In other embodiments of this application, the second voltage divider unit 12 includes seven third resistors. The resistance value of each third resistor can be, but is not limited to, the same value, or different values. The resistance value of the third resistor can be in the megaohm range (MΩ), and the resistance value of the fourth resistor R13 can be in the kiloohm range (KΩ). For example, the resistance value of the third resistor can be 1MΩ, and the resistance value of the fourth resistor R13 can be 3KΩ. This is beneficial for obtaining a voltage signal suitable for processing by the operational amplifier in the voltage follower module 20.

[0031] In some embodiments, such as Figure 2 As shown, the third voltage divider unit 13 includes multiple fifth resistors and a sixth resistor R45. The multiple fifth resistors are connected in series between the third live wire C and the third input terminal of the voltage follower module 20. The first end of the sixth resistor R45 is connected to the third input terminal of the voltage follower module 20 and the fifth resistors, and the second end of the sixth resistor R45 is connected to the ground terminal GND. The resistance value of the fifth resistor is greater than the resistance value of the sixth resistor R45.

[0032] It should be noted that the plurality of fifth resistors can be at least two of R128, R129, R130, R131, R132, R133, and R134. In other embodiments of this application, the third voltage divider unit 13 includes seven fifth resistors. The resistance value of each fifth resistor can be, but is not limited to, the same value, or different values. The resistance value of the fifth resistor can be in the megaohm range (MΩ), and the resistance value of the sixth resistor R45 can be in the kiloohm range (KΩ). For example, the resistance value of the fifth resistor can be 1MΩ, and the resistance value of the sixth resistor R45 can be 3KΩ. This is beneficial for obtaining a voltage signal suitable for processing by the operational amplifier in the voltage follower module 20.

[0033] In some embodiments, such as Figure 2As shown, the fourth voltage divider unit 14 includes multiple seventh resistors and an eighth resistor R167. The multiple seventh resistors are connected in series between the neutral line N and the fourth input terminal of the voltage follower module 20. The first end of the eighth resistor R167 is connected to the fourth input terminal of the voltage follower module 20 and the seventh resistors, and the second end of the eighth resistor R167 is connected to the ground terminal GND. The resistance value of the seventh resistor is greater than the resistance value of the eighth resistor R167.

[0034] It should be noted that the plurality of seventh resistors can be at least two of R160, R161, R162, R163, R164, R165, and R166. In other embodiments of this application, the fourth voltage divider unit 14 includes seven seventh resistors. The resistance value of each seventh resistor can be, but is not limited to, the same value, or different values. The resistance value of the seventh resistor can be in the megaohm range (MΩ), and the resistance value of the eighth resistor R167 can be in the kiloohm range (KΩ). For example, the resistance value of the seventh resistor can be 1MΩ, and the resistance value of the eighth resistor R167 can be 3KΩ. This is beneficial for obtaining a voltage signal suitable for processing by the operational amplifier in the voltage follower module 20.

[0035] In some embodiments, such as Figure 2 As shown, the voltage follower module 20 includes a first operational amplifier U3B, a second operational amplifier U3C, a third operational amplifier U7B, and a fourth operational amplifier U7C. The first input terminal of the first operational amplifier U3B is connected to the output terminal of the first voltage divider unit 11, and the second input terminal of the first operational amplifier U3B is connected to its output terminal and the first input terminal of the differential amplifier module 30. The first input terminal of the second operational amplifier U3C is connected to the output terminal of the second voltage divider unit 12, and the second input terminal of the second operational amplifier U3C is connected to its output terminal and the second input terminal of the differential amplifier module 30. The first input terminal of the third operational amplifier U7B is connected to the output terminal of the third voltage divider unit 13, and the second input terminal of the third operational amplifier U7B is connected to its output terminal and the third input terminal of the differential amplifier module 30. The first input terminal of the fourth operational amplifier U7C is connected to the output terminal of the fourth voltage divider unit 14, and the second input terminal of the fourth operational amplifier U7C is connected to its output terminal and the fourth input terminal of the differential amplifier module 30.

[0036] It should be noted that the first operational amplifier U3B, the second operational amplifier U3C, the third operational amplifier U7B, and the fourth operational amplifier U7C all function as voltage followers, which can isolate the output signal of the voltage divider module 10 from the subsequent signal and perform impedance transformation, thereby reducing signal attenuation and load effects, and thus avoiding the influence of load fluctuations in the subsequent circuit.

[0037] The first operational amplifier U3B performs voltage following on the first initial voltage output by the first voltage divider unit 11 to generate the first target voltage. The second operational amplifier U3C performs voltage following on the second initial voltage output by the second voltage divider unit 12 to generate the second target voltage. The third operational amplifier U7B performs voltage following on the third initial voltage output by the third voltage divider unit 13 to generate the third target voltage. The fourth operational amplifier U7C performs voltage following on the initial voltage of the neutral line output by the fourth voltage divider unit 14 to generate the neutral line target voltage.

[0038] In some embodiments, such as Figure 2 As shown, the phase sampling voltage includes a first sampling voltage A_VAP, a second sampling voltage A_VBP, and a third sampling voltage A_VCP. The differential amplifier module 30 includes a first differential amplifier unit 31, a second differential amplifier unit 32, and a third differential amplifier unit 33. The two input terminals of the first differential amplifier unit 31 are respectively connected to the output terminals of the first operational amplifier U3B and the fourth operational amplifier U7C, and the output terminal of the first differential amplifier unit 31 is configured to generate the first sampling voltage A_VAP. The two input terminals of the second differential amplifier unit 32 are respectively connected to the output terminals of the second operational amplifier U3C and the fourth operational amplifier U7C, and the output terminal of the second differential amplifier unit 32 is configured to generate the second sampling voltage A_VBP. The two input terminals of the third differential amplifier unit 33 are respectively connected to the output terminals of the third operational amplifier U7B and the fourth operational amplifier U7C, and the output terminal of the third differential amplifier unit 33 is configured to generate the third sampling voltage A_VCP.

[0039] It should be noted that the first differential amplification unit 31 is configured to differentially amplify the first target voltage and the neutral line target voltage to generate the first sampling voltage A_VAP. The second differential amplification unit 32 is configured to differentially amplify the second target voltage and the neutral line target voltage to generate the second sampling voltage A_VBP. The third differential amplification unit 33 is configured to differentially amplify the third target voltage and the neutral line target voltage to generate the third sampling voltage A_VCP. Through differential amplification processing, not only can the difference between each phase target voltage and the neutral line target voltage be extracted, but common-mode noise can also be effectively suppressed, thereby improving the anti-interference capability and measurement accuracy of the sampling voltage.

[0040] In some embodiments, such as Figure 2As shown, the first differential amplifier unit 31 includes a ninth resistor R15, a tenth resistor R18, an eleventh resistor R27, a twelfth resistor R26, and a fifth operational amplifier U3A. The first end of the ninth resistor R15 is connected to the output terminal of the first operational amplifier U3B; the first end of the tenth resistor R18 is connected to the ground terminal GND; the first end of the eleventh resistor R27 is connected to the output terminal of the fourth operational amplifier U7C; the first input terminal of the fifth operational amplifier U3A is connected to the second ends of the ninth resistor R15 and the tenth resistor R18; the second input terminal of the fifth operational amplifier U3A is connected to the second end of the eleventh resistor R27 and the first end of the twelfth resistor R26; and the output terminal of the fifth operational amplifier U3A is connected to the second end of the twelfth resistor R26.

[0041] It should be noted that the first input terminal and the second input terminal of the fifth operational amplifier U3A are, respectively, the positive input terminal (+) and the negative input terminal (-). In this embodiment, the first differential amplifier unit 31 can extract the voltage difference between the first target voltage and the neutral line target voltage and amplify this difference. This effectively suppresses the common-mode noise carried by the first target voltage and the neutral line target voltage, amplifying only the useful differential-mode signal, thereby significantly improving the anti-interference capability and accuracy of the measured first sampling voltage A_VAP.

[0042] In some embodiments, such as Figure 2 As shown, the second differential amplifier unit 32 includes a thirteenth resistor R16, a fourteenth resistor R17, a fifteenth resistor R29, a sixteenth resistor R28, and a sixth operational amplifier U3D. The first end of the thirteenth resistor R16 is connected to the output terminal of the second operational amplifier U3C; the first end of the fourteenth resistor R17 is connected to the ground terminal GND; the first end of the fifteenth resistor R29 is connected to the output terminal of the fourth operational amplifier U7C; the first input terminal of the sixth operational amplifier U3D is connected to the second ends of the thirteenth resistor R16 and the fourteenth resistor R17; the second input terminal of the sixth operational amplifier U3D is connected to the second end of the fifteenth resistor R29 and the first end of the sixteenth resistor R28; and the output terminal of the sixth operational amplifier U3D is connected to the second end of the sixteenth resistor R28.

[0043] It should be noted that the first and second input terminals of the sixth operational amplifier U3D are, respectively, the positive input terminal (+) and the negative input terminal (-). In this embodiment, the second differential amplifier unit 32 can extract the voltage difference between the second target voltage and the neutral target voltage, and amplify this difference. This effectively suppresses the common-mode noise carried by the second target voltage and the neutral target voltage, amplifying only the useful differential-mode signal, thereby significantly improving the anti-interference capability and accuracy of the measured second sampling voltage A_VBP.

[0044] In some embodiments, such as Figure 2 As shown, the third differential amplifier unit 33 includes a seventeenth resistor R34, an eighteenth resistor R35, a nineteenth resistor R44, a twentieth resistor R43, and a seventh operational amplifier U7A. The first end of the seventeenth resistor R34 is connected to the output terminal of the third operational amplifier U7B; the first end of the eighteenth resistor R35 is connected to the ground terminal GND; the first end of the nineteenth resistor R44 is connected to the output terminal of the fourth operational amplifier U7C; the first input terminal of the seventh operational amplifier U7A is connected to the second end of the seventeenth resistor R34 and the second end of the eighteenth resistor R35; the second input terminal of the seventh operational amplifier U7A is connected to the second end of the nineteenth resistor R44 and the first end of the twentieth resistor R43; and the output terminal of the seventh operational amplifier U7A is connected to the second end of the twentieth resistor R43.

[0045] It should be noted that the first and second input terminals of the seventh operational amplifier U7A are, respectively, the positive input terminal (+) and the negative input terminal (-). In this embodiment, the third differential amplifier unit 33 can extract the voltage difference between the third target voltage and the zero-line target voltage, and amplify this difference. This effectively suppresses the common-mode noise carried by the third target voltage and the zero-line target voltage, amplifying only the useful differential-mode signal, thereby significantly improving the anti-interference capability and accuracy of the measured third sampling voltage A_VCP.

[0046] In some embodiments, such as Figure 3 As shown, the sampling circuit 100 also includes a power supply module 40, which is connected to the voltage follower module 20 and the differential amplifier module 30, and is configured to provide positive and negative voltages of equal amplitude to the voltage follower module 20 and the differential amplifier module 30, respectively.

[0047] It should be noted that, in order to optimize the circuit layout and reduce circuit complexity, in this embodiment, the first operational amplifier U3B, the second operational amplifier U3C, the fifth operational amplifier U3A, and the sixth operational amplifier U3D can be integrated into the first operational amplifier chip, and the third operational amplifier U7B, the fourth operational amplifier U7C, and the seventh operational amplifier U7A can be integrated into the second operational amplifier chip, so as to facilitate the miniaturization of the circuit and the stable power supply.

[0048] Since the sampling circuit 100 samples the AC voltage of the power grid and has no corresponding DC power supply, this embodiment configures a power supply module 40 to provide dual power supply for the first and second operational amplifier chips. In this embodiment, the power supply module 40 can provide ±5V dual power supply to meet the operating requirements of the operational amplifiers. Of course, in other embodiments, other positive and negative power supplies with equal amplitudes, such as ±12V, can also be used.

[0049] In some embodiments, such as Figure 4 As shown, the power module 40 includes a first power supply unit U3E and a second power supply unit U7E. One of the first power supply unit U3E and the second power supply unit U7E can power the first operational amplifier chip, and the other of the first power supply unit U3E and the second power supply unit U7E can power the second operational amplifier chip. Specifically, the first power supply unit U3E is configured to provide ±5V dual power to the first operational amplifier chip (integrating the first operational amplifier U3B, the second operational amplifier U3C, the fifth operational amplifier U3A, and the sixth operational amplifier U3D), and the second power supply unit U7E is configured to provide ±5V dual power to the second operational amplifier chip (integrating the third operational amplifier U7B, the fourth operational amplifier U7C, and the seventh operational amplifier U7A) to meet the power supply requirements of the operational amplifier for sampling the AC voltage of the power grid.

[0050] It should be noted that the positive voltage can be, for example, +5V or +12V, and the negative voltage can be, for example, -5V or -12V.

[0051] In some embodiments, such as Figure 5 As shown, this embodiment also provides a metering circuit 200, which includes the above-mentioned sampling circuit 100 and metering module 210. The metering module 210 is connected to the output terminal of the differential amplifier module 30, and the metering module 210 is configured to perform metering based on the phase sampling voltage.

[0052] It is understood that, since the metering circuit 200 provided in this embodiment includes a sampling circuit 100, it can also be used through... Figure 1 , Figure 2 The voltage follower module 20 performs voltage follower on the initial voltage of the neutral wire and the initial voltage of the live wire, which can reduce the impact of load fluctuations in the subsequent circuits on the generated target voltages of the neutral wire and the live wire. The differential amplifier module 30 performs differential amplification on the target voltage of the neutral wire and each target voltage of the live wire to generate the corresponding phase sampling voltage. This can eliminate the fluctuations of each phase voltage introduced by the high resistance of the neutral wire N, thereby obtaining a stable and smooth phase sampling voltage. This not only improves the sampling accuracy, but also improves the measurement accuracy of the metering module 210.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0054] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A sampling circuit, characterized in that, The sampling circuit includes: A voltage divider module, which is connected to a neutral wire and at least one live wire, is configured to divide the voltage of the neutral wire and the voltage of the live wire respectively to generate corresponding initial voltages for the neutral wire and live wire respectively. A voltage follower module, connected to the voltage divider module, is configured to perform voltage following on the initial voltage of the neutral wire and the initial voltage of the live wire, so as to generate corresponding target voltages for the neutral wire and the live wire, respectively. The differential amplifier module, connected to the voltage follower module, is configured to differentially amplify the neutral target voltage and each of the live target voltages to generate corresponding phase sampling voltages.

2. The sampling circuit according to claim 1, characterized in that, The at least one live wire includes a first live wire, a second live wire, and a third live wire, and the voltage divider module includes: The first voltage divider unit is connected to the first live wire and the first input terminal of the voltage follower module; The second voltage divider unit is connected to the second live wire and the second input terminal of the voltage follower module; The third voltage divider unit is connected to the third live wire and the third input terminal of the voltage follower module; The fourth voltage divider unit is connected to the neutral line and the fourth input terminal of the voltage follower module.

3. The sampling circuit according to claim 2, characterized in that, The first voltage divider unit includes: Multiple first resistors are connected in series between the first live wire and the first input terminal of the voltage follower module; The second resistor has a first end connected to the first input terminal of the voltage follower module and the first resistor, and a second end connected to the ground terminal. Wherein, the resistance value of the first resistor is greater than the resistance value of the second resistor; The second voltage divider unit includes: Multiple third resistors are connected in series between the second live wire and the second input terminal of the voltage follower module; The fourth resistor has its first end connected to the second input terminal of the voltage follower module and the third resistor, and its second end connected to the ground terminal. Wherein, the resistance value of the third resistor is greater than the resistance value of the fourth resistor; The third voltage divider unit includes: Multiple fifth resistors are connected in series between the third live wire and the third input terminal of the voltage follower module; The sixth resistor has its first end connected to the third input terminal of the voltage follower module and the fifth resistor, and its second end connected to the ground terminal. Wherein, the resistance value of the fifth resistor is greater than the resistance value of the sixth resistor; The fourth voltage divider unit includes: Multiple seventh resistors are connected in series between the neutral line and the fourth input terminal of the voltage follower module; The eighth resistor has its first end connected to the fourth input terminal of the voltage follower module and the seventh resistor, and its second end connected to the ground terminal. The resistance value of the seventh resistor is greater than that of the eighth resistor.

4. The sampling circuit according to any one of claims 2 or 3, characterized in that, The voltage follower module includes: A first operational amplifier, wherein the first input terminal of the first operational amplifier is connected to the output terminal of the first voltage divider unit, and the second input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier and the first input terminal of the differential amplifier module; The second operational amplifier has its first input terminal connected to the output terminal of the second voltage divider unit, and its second input terminal connected to both the output terminal of the second operational amplifier and the second input terminal of the differential amplifier module. The third operational amplifier has its first input terminal connected to the output terminal of the third voltage divider unit, and its second input terminal connected to both the output terminal of the third operational amplifier and the third input terminal of the differential amplifier module. The fourth operational amplifier has its first input terminal connected to the output terminal of the fourth voltage divider unit, and its second input terminal connected to both the output terminal of the fourth operational amplifier and the fourth input terminal of the differential amplifier module.

5. The sampling circuit according to claim 4, characterized in that, The phase sampling voltage includes a first sampling voltage, a second sampling voltage, and a third sampling voltage. The differential amplification module includes: The first differential amplifier unit has two input terminals connected to the output terminals of the first operational amplifier and the fourth operational amplifier, respectively, and the output terminal of the first differential amplifier unit is configured to generate the first sampling voltage. The second differential amplifier unit has two input terminals connected to the output terminals of the second operational amplifier and the fourth operational amplifier, respectively, and the output terminal of the second differential amplifier unit is configured to generate the second sampling voltage. The third differential amplifier unit has two input terminals connected to the output terminals of the third operational amplifier and the fourth operational amplifier, respectively, and its output terminal is configured to generate the third sampling voltage.

6. The sampling circuit according to claim 5, characterized in that, The first differential amplifier unit includes: The ninth resistor, the first end of which is connected to the output terminal of the first operational amplifier; The tenth resistor, the first end of which is connected to the ground terminal; The eleventh resistor, the first end of which is connected to the output terminal of the fourth operational amplifier; The twelfth resistor; The fifth operational amplifier has its first input terminal connected to the second terminal of the ninth resistor and the second terminal of the tenth resistor, its second input terminal connected to the second terminal of the eleventh resistor and the first terminal of the twelfth resistor, and its output terminal connected to the second terminal of the twelfth resistor.

7. The sampling circuit according to claim 6, characterized in that, The second differential amplifier unit includes: The thirteenth resistor, the first end of which is connected to the output terminal of the second operational amplifier; The fourteenth resistor, the first end of which is connected to the ground terminal; The fifteenth resistor, the first end of which is connected to the output terminal of the fourth operational amplifier; The sixteenth resistor; The sixth operational amplifier has its first input terminal connected to the second terminal of the thirteenth resistor and the second terminal of the fourteenth resistor, its second input terminal connected to the second terminal of the fifteenth resistor and the first terminal of the sixteenth resistor, and its output terminal connected to the second terminal of the sixteenth resistor.

8. The sampling circuit according to claim 7, characterized in that, The third differential amplification unit includes: The seventeenth resistor, the first end of which is connected to the output terminal of the third operational amplifier; The eighteenth resistor, the first end of which is connected to the ground terminal; The nineteenth resistor, the first end of which is connected to the output terminal of the fourth operational amplifier; The twentieth resistor; The seventh operational amplifier has its first input terminal connected to the second terminals of the seventeenth and eighteenth resistors, its second input terminal connected to the second terminal of the nineteenth and twentieth resistors, and its output terminal connected to the second terminal of the twentieth resistor.

9. The sampling circuit according to claim 8, characterized in that, The first operational amplifier, the second operational amplifier, the fifth operational amplifier, and the sixth operational amplifier are integrated with a first operational amplifier chip, and the third operational amplifier, the fourth operational amplifier, and the seventh operational amplifier are integrated with a second operational amplifier chip.

10. The sampling circuit according to any one of claims 1-3, characterized in that, The sampling circuit further includes a power supply module, which is connected to the voltage follower module and the differential amplifier module, and is configured to provide positive and negative voltages of equal amplitude to the voltage follower module and the differential amplifier module, respectively.

11. A metering circuit, characterized in that, The metering circuit includes: The sampling circuit as described in any one of claims 1-10; The metering module, connected to the output of the differential amplifier module, is configured to perform metering based on the phase sampling voltage.

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