CN218567469U

CN218567469U - Three-phase four-wire electric energy metering circuit and electric energy meter

Info

Publication number: CN218567469U
Application number: CN202221279262.2U
Authority: CN
Inventors: 李秋实; 苗书立; 易文
Original assignee: SHENZHEN RENERGY TECHNOLOGY CO LTD
Current assignee: SHENZHEN RENERGY TECHNOLOGY CO LTD
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2023-03-03
Anticipated expiration: 2032-05-25

Abstract

The utility model provides an electric energy metering circuit and electric energy meter of three-phase four-wire, includes: the voltage sampling circuit detects each phase voltage of the three-phase power grid to output an analog voltage sampling signal of each phase voltage; the current sampling circuit detects each phase current and neutral current of the three-phase power grid to respectively output an analog current sampling signal of each phase current and an analog current sampling signal of the neutral current; the metering circuit converts the analog voltage sampling signal into a digital voltage sampling signal according to the reference clock signal and converts the analog current sampling signal into a digital current sampling signal according to the reference clock signal; the control circuit is configured to output a reference clock signal, and the reference clock signal is used for operating a digital voltage sampling signal of each phase voltage, a digital current sampling signal of each phase current and a digital current sampling signal of a neutral line current so as to output an electric parameter of a three-phase power grid; the digital current sampling signal and the digital voltage sampling signal are single-bit signals; the signal transmission speed and the metering accuracy are improved.

Description

Three-phase four-wire electric energy metering circuit and electric energy meter

Technical Field

The application belongs to the technical field of electric energy metering, and particularly relates to an electric energy metering circuit and an electric energy meter of a three-phase four-wire system.

Background

The electric energy meter in the prior art uses three single-phase metering chips to respectively collect voltage signals and current signals of an A phase, a B phase and a C phase, the single-phase metering chips and the single chip processor are communicated in a UART mode, the UART is a two-line full duplex communication mode, and signal isolation processing is carried out on a UART signal line. The electric energy meter in the prior art reads the split-phase power, then calculates the phase-combining power, and generates pulses by calculating the phase-combining power, the calculated phase-combining power lags the actual use power of the electric energy meter due to the restriction of the communication rate of a UART mode and the application program processing rate of a singlechip processor, and the calculated phase-combining power cannot reflect the actual use power of the current load in real time when the actual power changes.

Therefore, the electric energy meter in the prior art has the problem that the actual use power of the current load cannot be reflected in real time by the three-phase-combination power.

SUMMERY OF THE UTILITY MODEL

The application aims to provide a three-phase four-wire electric energy metering circuit and an electric energy meter, and aims to solve the problem that the traditional electric energy meter cannot reflect the actual use power of the current load in real time due to the three-phase combination power.

A first aspect of the embodiments of the present application provides an electric energy metering circuit of three-phase four-wire, including:

the voltage sampling circuit is configured to be connected to a three-phase power grid, and detect each phase voltage of the three-phase power grid so as to output an analog voltage sampling signal of each phase voltage;

the current sampling circuit is configured to be connected to the three-phase power grid, detect each phase current and a neutral current of the three-phase power grid and output an analog current sampling signal of each phase current and an analog current sampling signal of the neutral current;

a metering circuit connected to the voltage sampling circuit and the current sampling circuit, and configured to convert the analog voltage sampling signal of each phase voltage into a digital voltage sampling signal of each phase voltage according to a reference clock signal, convert the analog current sampling signal of each phase current into a digital current sampling signal of each phase current according to the reference clock signal, and convert the analog current sampling signal of the neutral current into a digital current sampling signal of the neutral current according to the reference clock signal;

the control circuit is connected with the metering circuit and is configured to output the reference clock signal, and the digital voltage sampling signal of each phase voltage, the digital current sampling signal of the phase current and the digital current sampling signal of the neutral current are operated to output the electrical parameters of the three-phase power grid;

the digital current sampling signal and the digital voltage sampling signal are single-bit signals.

In one embodiment, the voltage sampling circuit includes:

an A-phase voltage detection component configured to detect an A-phase voltage to output an analog voltage sampling signal of the A-phase voltage;

the B-phase voltage detection component is configured to detect B-phase voltage to output an analog voltage sampling signal of the B-phase voltage;

the device comprises a C phase voltage detection component and a control component, wherein the C phase voltage detection component is configured to detect C phase voltage to output an analog voltage sampling signal of the C phase voltage.

In one embodiment, each of the a-phase voltage detection assembly, the B-phase voltage detection assembly and the C-phase voltage detection assembly comprises a voltage detection module, and the voltage detection module comprises a resistor string composed of n resistors, a first resistor, a second resistor, a first capacitor and a second capacitor, wherein n is a positive integer and n is larger than or equal to 1;

the first end of the resistor string is used as a single-phase voltage input end of the voltage detection module and is connected with the three-phase power grid so as to be connected with a single-phase voltage;

the second end of the resistor string, the first end of the first resistor, the first end of the first capacitor, the second end of the second resistor and the second end of the second capacitor are jointly used as an analog voltage sampling signal output end of the voltage detection module and connected with the metering circuit to output the analog voltage sampling signal of the single-phase voltage;

the second end of the first resistor, the first end of the second resistor, the second end of the first capacitor and the first end of the second capacitor are connected to the power ground in common.

In one embodiment, the current sampling circuit includes:

the A-phase current detection assembly is configured to detect the A-phase current by adopting a manganin sheet so as to output an analog current sampling signal of the A-phase current;

the phase B current detection assembly is configured to detect the phase B current by adopting a manganin sheet so as to output an analog current sampling signal of the phase B current;

the C-phase current detection assembly is configured to detect the C-phase current by adopting a manganin sheet so as to output an analog current sampling signal of the C-phase current;

and the neutral current detection assembly is configured to detect the neutral current by adopting a manganin sheet so as to output an analog current sampling signal of the neutral current.

In one embodiment, the a-phase current detection component, the B-phase current detection component, the C-phase current detection component and the neutral current detection component each comprise a current detection module, and the current detection module comprises a manganese copper sheet, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor and a fourth capacitor;

the first end of the manganous sheet, the first end of the third resistor, the first end of the fourth resistor and the first end of the fifth resistor are used as a single-phase current input end of the current detection module or a neutral current input end of the current detection module together to access the single-phase current or the neutral current;

the second end of the fifth resistor, the first end of the third capacitor, the first end of the sixth resistor and the second end of the fourth capacitor are used as an analog current sampling signal output end of the current detection module together, and are connected with the metering circuit to output an analog current sampling signal of the single-phase current or an analog current sampling signal of the neutral line current;

the second end of the seventh resistor, the second end of the sixth resistor, the second end of the third resistor and the second end of the manganese copper sheet are used as a single-phase current output end of the current detection module or a neutral current output end of the current detection module together to output the single-phase current or the neutral current;

and the second end of the fourth resistor, the first end of the seventh resistor, the second end of the third capacitor and the first end of the fourth capacitor are connected to a power ground in common.

In one embodiment, the metering circuit comprises:

the A-phase metering component is connected with the A-phase voltage detection component, the A-phase current detection component and the control circuit and is configured to convert an analog voltage sampling signal of the A-phase voltage into a digital voltage sampling signal of the A-phase voltage according to the reference clock signal and convert an analog current sampling signal of the A-phase current into a digital current sampling signal of the A-phase current according to the reference clock signal;

the B-phase metering component is connected with the B-phase voltage detection component, the B-phase current detection component and the control circuit, and is configured to convert an analog voltage sampling signal of the B-phase voltage into a digital voltage sampling signal of the B-phase voltage according to the reference clock signal and convert an analog current sampling signal of the B-phase current into a digital current sampling signal of the B-phase current according to the reference clock signal;

the C-phase metering component is connected with the C-phase voltage detection component, the C-phase current detection component and the control circuit, and is configured to convert an analog voltage sampling signal of the C-phase voltage into a digital voltage sampling signal of the C-phase voltage according to the reference clock signal and convert an analog current sampling signal of the C-phase current into a digital current sampling signal of the C-phase current according to the reference clock signal;

a neutral metering component coupled to the neutral current detection component and the control circuit and configured to convert an analog current sample signal of the neutral current to a digital current sample signal of the neutral current based on the reference clock signal.

In one embodiment, the phase a metrology assembly, the phase B metrology assembly, the phase C metrology assembly, and the neutral metrology assembly each comprise a metrology module comprising a single phase metrology chip;

the positive analog input end of the voltage channel of the single-phase metering chip and the negative analog input end of the voltage channel of the single-phase metering chip are used as the analog voltage sampling signal input end of the single-phase voltage of the metering module and are connected with the voltage sampling circuit so as to access the analog voltage sampling signal of the single-phase voltage;

the current channel positive analog input end of the single-phase metering chip and the current channel negative analog input end of the single-phase metering chip are used as analog current sampling signal input ends of single-phase current of the metering module and are connected with the current sampling circuit so as to access an analog current sampling signal of the single-phase current or an analog current sampling signal of the neutral current;

a voltage channel ADC sampling signal output end of the single-phase metering chip is used as a digital voltage sampling signal output end of the single-phase voltage of the metering module and is connected with the control circuit so as to output a digital voltage sampling signal of the single-phase voltage;

a current channel ADC sampling signal output end of the single-phase metering chip is used as a digital current sampling signal output end of the single-phase current of the metering module and is connected with the control circuit so as to output a digital current sampling signal of the single-phase current or a digital current sampling signal of the neutral current;

and the external irrigation system clock input end of the single-phase metering chip is used as the reference clock signal input end of the metering module and is connected with the control circuit so as to access the reference clock signal.

In one embodiment, the metering circuit further comprises:

the phase A isolation component is connected between the phase A metering component and the control circuit and is configured to capacitively couple and isolate the digital voltage sampling signal of the phase A voltage and the digital current sampling signal of the phase A current;

the phase B isolation component is connected between the phase B metering component and the control circuit and is configured to capacitively couple and isolate the digital voltage sampling signal of the phase B voltage and the digital current sampling signal of the phase B current;

the C phase isolation assembly is connected between the C phase metering assembly and the control circuit and is configured to capacitively couple and isolate the digital voltage sampling signal of the C phase voltage and the digital current sampling signal of the C phase current;

and the neutral line isolation assembly is connected between the neutral line metering assembly and the control circuit and is configured to capacitively couple and isolate the digital current sampling signal of the neutral line.

In one embodiment, the phase a isolation assembly, the phase B isolation assembly, the phase C isolation assembly, and the neutral isolation assembly comprise isolation modules; the isolation module comprises a capacitive coupling isolator;

a first input end of the capacitive coupling isolator is used as a digital voltage sampling signal input end of single-phase voltage of the isolation module and is connected with the single-phase metering assembly so as to access the digital voltage sampling signal of the single-phase voltage;

a second input end of the capacitive coupling isolator is used as a digital current sampling signal input end of single-phase current of the isolation module and is connected with the metering assembly of the single phase so as to access the digital current sampling signal of the single-phase current or the digital current sampling signal of the neutral current;

a first output end of the capacitive coupling isolator is used as a digital voltage sampling signal output end of the single-phase voltage of the isolation module and is connected with the control circuit so as to output the digital voltage sampling signal of the single-phase voltage after capacitive coupling isolation;

a second output end of the capacitive coupling isolator is used as a digital current sampling signal output end of the single-phase current of the isolation module and is connected with the control circuit so as to output a digital current sampling signal of the single-phase current after capacitive coupling isolation or a digital current sampling signal of the neutral current;

a third input end of the capacitive coupling isolator is used as a reference clock signal input end of the isolation module and is connected with the control circuit so as to access the reference clock signal;

and a third output end of the capacitive coupling isolator is used as a reference clock signal output end of the isolation module and is connected with the single-phase metering assembly so as to output the reference clock signal after capacitive coupling isolation.

In one embodiment, the control circuit comprises a three-phase metering chip;

the first voltage external ADC input end of the three-phase metering chip is used as the digital voltage sampling signal input end of the A-phase voltage of the control circuit and is connected with the metering circuit so as to access the digital voltage sampling signal of the A-phase voltage; the second voltage external ADC input end of the three-phase metering chip is used as the digital voltage sampling signal input end of the B-phase voltage of the control circuit and is connected with the metering circuit so as to access the digital voltage sampling signal of the B-phase voltage; the third voltage external ADC input end of the three-phase metering chip is used as the digital voltage sampling signal input end of the C-phase voltage of the control circuit and is connected with the metering circuit so as to access the digital voltage sampling signal of the C-phase voltage;

the external ADC input end of the first current of the three-phase metering chip is used as the digital current sampling signal input end of the phase A current of the control circuit and is connected with the metering circuit so as to access the digital current sampling signal of the phase A current; the second current external ADC input end of the three-phase metering chip is used as the digital current sampling signal input end of the phase B current of the control circuit and is connected with the metering circuit so as to access the digital current sampling signal of the phase B current; the third current external ADC input end of the three-phase metering chip is used as the digital current sampling signal input end of the C-phase current of the control circuit and is connected with the metering circuit so as to access the digital current sampling signal of the C-phase current; the fourth current external ADC input end of the three-phase metering chip is used as the digital current sampling signal input end of the neutral line current of the control circuit and is connected with the metering circuit so as to be connected with the digital current sampling signal of the neutral line current;

and the external irrigation clock output end of the three-phase metering chip is used as a reference clock signal output end of the control circuit and is connected with the metering circuit so as to output the reference clock signal.

A second aspect of the embodiments of the present application provides an electric energy meter, including the electric energy metering circuit as described in any one of the above first aspects.

Compared with the prior art, the embodiment of the utility model beneficial effect who exists is:

the voltage sampling circuit detects each phase voltage of the three-phase power grid to output an analog voltage sampling signal of each phase voltage; the current sampling circuit detects each phase current and neutral current of the three-phase power grid to output an analog current sampling signal of each phase current and an analog current sampling signal of the neutral current; the metering circuit converts the analog voltage sampling signal into a digital voltage sampling signal according to the reference clock signal and converts the analog current sampling signal into a digital current sampling signal according to the reference clock signal; the control circuit outputs a reference clock signal, and calculates a digital voltage sampling signal of each phase voltage, a digital current sampling signal of each phase current and a digital current sampling signal of a neutral line current to output an electric parameter of a three-phase power grid; the digital current sampling signal and the digital voltage sampling signal are single-bit signals; the metering circuit and the control circuit are transmitted by adopting a single-bit signal, so that the transmission speed is high, and the actual use power of the current load can be reflected in real time by the three-phase-combination power of the electric energy meter; and the metering circuit uses the same clock to convert the analog voltage sampling signal of each phase voltage, the analog current sampling signal of each phase current and the analog current sampling signal of the neutral line current, so that the A \ B \ C phases have a common clock reference on the clock in the clock phase, the parameter values of phase angle, electric energy and the like can be directly obtained through the control circuit, the calculation precision of the electric energy meter is improved, and the performance of the electric energy meter is further improved.

Drawings

Fig. 1 is a schematic structural diagram of a three-phase four-wire electric energy metering circuit provided in an embodiment of the present application;

fig. 2 is a schematic structural diagram of voltage detection components of a voltage sampling circuit according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of current detection components of a voltage sampling circuit according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of various metering components of a metering circuit according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of isolation components of a metrology circuit according to an embodiment of the present disclosure;

fig. 6 is a schematic diagram of a partial example circuit structure of a voltage detection module of a voltage sampling circuit according to an embodiment of the present disclosure;

fig. 7 is a schematic diagram of a partial example circuit structure of a current detection module of a current sampling circuit according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of a partial example circuit structure of a metering module and an isolation module of a metering circuit according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of a partial example circuit structure of a three-phase metering chip of a control circuit according to an embodiment of the present disclosure;

fig. 10 is a specific structural diagram of a three-phase four-wire electric energy metering circuit provided in an embodiment of the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

The following is a detailed description of specific embodiments.

Fig. 1 shows a schematic structural diagram of a three-phase four-wire electric energy metering circuit provided in a preferred embodiment of the present application, and for convenience of description, only the parts related to the present embodiment are shown, and detailed descriptions are as follows:

as shown in fig. 1, a first aspect of the embodiments of the present application provides a three-phase four-wire electric energy metering circuit, which includes a voltage sampling circuit 100, a current sampling circuit 200, a metering circuit 300, and a control circuit 400.

The voltage sampling circuit 100 is configured to be connected to a three-phase power grid, and detect each phase voltage of the three-phase power grid to output an analog voltage sampling signal of each phase voltage.

The current sampling circuit 200 is configured to be connected to a three-phase power grid, and detect each phase current and a neutral current of the three-phase power grid to output an analog current sampling signal of each phase current and an analog current sampling signal of the neutral current.

The metering circuit 300 is connected to the voltage sampling circuit 100 and the current sampling circuit 200, and is configured to convert the analog voltage sampling signal of each phase voltage into a digital voltage sampling signal of each phase voltage according to the reference clock signal, convert the analog current sampling signal of each phase current into a digital current sampling signal of each phase current according to the reference clock signal, and convert the analog current sampling signal of the neutral current into a digital current sampling signal of the neutral current according to the reference clock signal.

And a control circuit 400 connected to the metering circuit 300 and configured to output the reference clock signal, and to perform an operation on the digital voltage sampling signal of each phase voltage, the digital current sampling signal of each phase current, and the digital current sampling signal of the neutral current to output an electrical parameter of the three-phase power grid.

The digital voltage sampling signal of each phase voltage, the digital current sampling signal of each phase current, and the digital current sampling signal of the neutral current may be single-bit signals.

As shown in fig. 2, in one embodiment, the voltage sampling circuit 100 includes an a-phase voltage detection component 110, a B-phase voltage detection component 120, and a C-phase voltage detection component 130.

An a-phase voltage detection component 110 configured to detect an a-phase voltage to output an analog voltage sampling signal of the a-phase voltage; a B-phase voltage detection component 120 configured to detect a B-phase voltage to output an analog voltage sampling signal of the B-phase voltage; the C-phase voltage detection component 130 is configured to detect a C-phase voltage to output an analog voltage sampling signal of the C-phase voltage.

Because the a-phase voltage detection component 110, the B-phase voltage detection component 120 and the C-phase voltage detection component 130 respectively perform voltage sampling on the voltages of the three phases and output analog voltage sampling signals of the voltages of the phases, more accurate electric energy parameters can be obtained.

As shown in FIG. 3, in one embodiment, the current sampling circuit 200 includes an A-phase current detection component 210, a B-phase current detection component 220, a C-phase current detection component 230, and a neutral current detection component 240.

The a-phase current detection component 210 is configured to detect the a-phase current by using a manganin sheet to output an analog current sampling signal of the a-phase current; a B-phase current detection component 220 configured to detect the B-phase current using a manganin sheet to output an analog current sampling signal of the B-phase current; a C-phase current detecting component 230 configured to detect the C-phase current using a manganin sheet to output an analog current sampling signal of the C-phase current; the neutral current detection assembly 240 is configured to detect the neutral current using the manganin sheet to output an analog current sampling signal of the neutral current.

The a-phase current detection component 210, the B-phase current detection component 220, the C-phase current detection component 230 and the neutral current detection component 240 respectively perform current sampling on the three-phase current and the neutral current, and output analog current sampling signals of each phase current and analog current sampling signals of the neutral current, which is beneficial to obtaining more accurate electric energy parameters.

The prior art electric energy meter mainly uses a mature Current Transformer (CT) sampling circuit in a multifunctional three-phase meter, but has the following disadvantages: the direct current component is easy to saturate, so that the metering error becomes large; the device is easily interfered by a constant magnetic field, so that the metering error is increased; the volume is large, and the installation is not easy; the nonlinear components have angular differences; for different subharmonics, the attenuation amplitude and phase shift are different, and the cost is higher, for example, the direct current magnetic bias resisting mutual inductor has the defects of high price and poor precision at high temperature of 0.5L.

The manganin sheet sampling is adopted in the embodiment, and the method has the following advantages: the manganese copper sheet is a pure resistive component, can completely truly reflect the waveform of a power grid in real time, and has no condition of quick saturation influence error under the condition of direct current component; is not influenced by a constant magnetic field; the volume is small and the installation is easy; the cost is low; the nonlinear element has no angular difference.

As shown in fig. 4, in one embodiment, the metering circuit 300 includes a phase a metering component 311, a phase B metering component 312, a phase C metering component 313, and a neutral metering component 314.

The a-phase metering component 311 is connected to the a-phase voltage detecting component 110, the a-phase current detecting component 210, and the control circuit 400, and configured to convert an analog voltage sampling signal of the a-phase voltage into a digital voltage sampling signal of the a-phase voltage according to the reference clock signal, and convert an analog current sampling signal of the a-phase current into a digital current sampling signal of the a-phase current according to the reference clock signal.

The phase B metering component 312 is connected to the phase B voltage detecting component 120, the phase B current detecting component 220, and the control circuit 400, and configured to convert an analog voltage sampling signal of the phase B voltage into a digital voltage sampling signal of the phase B voltage according to the reference clock signal, and convert an analog current sampling signal of the phase B current into a digital current sampling signal of the phase B current according to the reference clock signal.

The C-phase metering component 313 is connected to the C-phase voltage detecting component 130, the C-phase current detecting component 230, and the control circuit 400, and configured to convert the analog voltage sampling signal of the C-phase voltage into a digital voltage sampling signal of the C-phase voltage according to the reference clock signal, and convert the analog current sampling signal of the C-phase current into a digital current sampling signal of the C-phase current according to the reference clock signal.

The neutral metering component 314, coupled to the neutral current detecting component 240 and the control circuit 400, is configured to convert an analog current sample signal of the neutral current to a digital current sample signal of the neutral current according to the reference clock signal.

Through the A-phase metering component 311, the B-phase metering component 312, the C-phase metering component 313 and the neutral line metering component 314, the transmission efficiency is improved, and the control circuit can conveniently calculate the electric energy parameters according to the digital sampling signals.

As shown in FIG. 5, in one embodiment, the metering circuit 300 further includes an isolated A block 321, an isolated B block 322, an isolated C block 323, and a neutral isolation block 324.

The phase a isolation component 321 is connected between the phase a metering component 311 and the control circuit 400, and configured to capacitively couple and isolate the digital voltage sampling signal of the phase a voltage and the digital current sampling signal of the phase a current.

The phase B isolation assembly 322 is connected between the phase B metering assembly 312 and the control circuit 400, and configured to capacitively isolate the digital voltage sampling signal of the phase B voltage and the digital current sampling signal of the phase B current.

The C phase isolating component 323 is connected between the C phase metering component 313 and the control circuit 400, and is configured to capacitively isolate the digital voltage sampling signal of the C phase voltage and the digital current sampling signal of the C phase current.

The neutral isolation assembly 324 is coupled between the neutral metering assembly 314 and the control circuit 400 and configured to capacitively isolate the digital current sample signal of the neutral.

Because the isolation component electrically isolates the digital current sampling signal of the strong current end from the control circuit 400 of the weak current end in a capacitive coupling isolation mode, the requirement of safety in a power utilization scene that the control circuit 400 needs to control strong current equipment by using a weak current signal is met, and the voltage resistance of the electric energy meter is enhanced.

In another embodiment, the metering circuit 300 further includes a filter circuit, wherein the filter circuit performs filtering processing on a 1-bit digital voltage signal U _1bit _INof the single-phase voltage after capacitive coupling isolation, and then inputs the signal into the control circuit 400; the filter circuit filters the 1-bit digital current signal I _1bit _inof the single-phase current or neutral line current after capacitive coupling isolation, and inputs the signal to the control circuit 400. The filter current may be an RC filter circuit.

Fig. 6 shows a partial example circuit structure of a voltage detection module in the electric energy metering circuit of three-phase four-wire that the embodiment of the utility model provides, fig. 7 shows a partial example circuit structure of a current detection module in the electric energy metering circuit of three-phase four-wire that the embodiment of the utility model provides a partial example circuit structure of metering module in the electric energy metering circuit of three-phase four-wire that provides, fig. 8 shows a partial example circuit structure of isolation module in the electric energy metering circuit of three-phase four-wire that the embodiment of the utility model provides a, fig. 9 shows a partial example circuit structure of control circuit in the electric energy metering circuit of three-phase four-wire that the embodiment of the utility model provides, for the convenience of explanation, only shown with the embodiment of the utility model relates to relevant part, the detailed description is as follows:

the a-phase voltage detection module 110, the B-phase voltage detection module 120, and the C-phase voltage detection module 130 each include a voltage detection module. As shown in fig. 6, the voltage detection module includes a resistor string Rn composed of n resistors, a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2.

The first end of the resistor string Rn is used as a single-phase voltage input end of the voltage detection module and is connected with a three-phase power grid so as to be connected with a single-phase voltage UN; the second end of the resistor string Rn, the first end of the first resistor R1, the first end of the first capacitor C1, the second end of the second resistor R2 and the second end of the second capacitor C2 are used as analog voltage sampling signal output ends of the voltage detection module, and are connected to the metering circuit 300 to output analog voltage sampling signals of single-phase voltage; the second end of the first resistor R1, the first end of the second resistor R2, the second end of the first capacitor C1, and the first end of the second capacitor C2 are commonly connected to the power ground.

In addition, taking phase a as an example, the second end of the resistor string Rn, the first end of the first resistor R1, and the first end of the first capacitor C1 are collectively used as a first analog voltage sampling signal output end of the voltage detection module, and are connected to the metering circuit 300, so as to output a positive analog voltage sampling signal VAP of the phase a voltage.

The second end of the second resistor R2 and the second end of the second capacitor C2 are used as a second analog voltage sampling signal output end of the voltage detection module, and are connected to the metering circuit 300 to output a negative analog voltage sampling signal VAN of a single-phase voltage.

The resistor string can divide the voltage of each phase of the phase voltage signal, and the capacitor filters clutter signals in the voltage sampling signal, so that a stable analog voltage sampling signal can be conveniently obtained.

Preferably, the resistances of the resistors in the resistor string Rn are equal or unequal, N is a positive integer and N ≧ 1, and further N is 8. The specific value of n is not limited in this embodiment, and the value of n of the resistor string is set according to the requirement of the voltage sampling circuit of the electric energy meter.

The a-phase current detecting component 210, the B-phase current detecting component 220, the C-phase current detecting component 230, and the neutral current detecting component 240 each include a current detecting module. As shown in fig. 7, the current detection module includes a manganese copper sheet MTA, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, and a fourth capacitor C4.

The first end of the manganese copper sheet MTA, the first end of the third resistor R3, the first end of the fourth resistor R4 and the first end of the fifth resistor R5 are jointly used as a single-phase current input end of the current detection module or a neutral current input end of the current detection module to be connected with single-phase current or neutral current.

The second end of the fifth resistor R5, the first end of the third capacitor C3, the first end of the sixth resistor R6, and the second end of the fourth capacitor C4 are used together as an output end of the analog current sampling signal of the current detection module to output the analog current sampling signal of the single-phase current or the analog current sampling signal of the neutral current.

The second end of the seventh resistor R7, the second end of the sixth resistor R6, the second end of the third resistor R3 and the second end of the manganese copper sheet MTA are used as a single-phase current output end of the current detection module or a neutral current output end of the current detection module together to output a single-phase current or a neutral current.

The second end of the fourth resistor R4, the first end of the seventh resistor R7, the second end of the third capacitor C3, and the first end of the fourth capacitor C4 are commonly connected to the power ground.

It should be noted that the second end of the fifth resistor R5 and the first end of the third capacitor C3 together serve as a first analog current sampling signal output end of the current detection module to output a positive analog current sampling signal of the single-phase current or a positive analog current sampling signal of the neutral current.

A first end of the sixth resistor R6 and a second end of the fourth capacitor C4 are used together as a second analog current sampling signal output end of the current detection module to output a negative analog current sampling signal of a single-phase current or a negative analog current sampling signal of a neutral current.

The phase a metrology assembly 311, the phase B metrology assembly 312, the phase C metrology assembly 313, and the neutral metrology assembly 314 each comprise metrology modules. As shown in fig. 8, the metering module includes a single-phase metering chip U1.

The positive analog input end V2P of the voltage channel and the negative analog input end V2N of the voltage channel of the single-phase metering chip U1 are used as analog voltage sampling signal input ends of single-phase voltage of the metering module and connected with the voltage sampling circuit 100 so as to access analog voltage sampling signals of the single-phase voltage.

The current channel positive analog input end V1P and the current channel negative analog input end V1N of the single-phase metering chip U1 are used as analog current sampling signal input ends of single-phase current of the metering module and are connected with the current sampling circuit 200 so as to be connected with an analog current sampling signal of the single-phase current or an analog current sampling signal of neutral current.

The voltage channel ADC sampling signal output terminal ADC _ UOUT of the single-phase metering chip U1 is connected to the control circuit 400 as a digital voltage sampling signal output terminal of the single-phase voltage of the metering module, so as to output a digital voltage sampling signal of the single-phase voltage.

The current channel ADC sampling signal output terminal ADC _ IOUT of the single-phase metering chip U1 is connected to the control circuit 400 as a digital current sampling signal output terminal of the single-phase current of the metering module, so as to output a digital current sampling signal of the single-phase current or a digital current sampling signal of the neutral current.

The external irrigation system clock input end of the single-phase metering chip U1 serves as a reference clock signal input end of the metering module and is connected with the control circuit 400 to access a reference clock signal.

More specifically, the single-phase metering chip amplifies the analog voltage signal and the analog current signal, converts the amplified analog voltage signal into a 1-bit digital voltage sampling signal, converts the amplified analog current signal into a 1-bit digital current sampling signal, acquires the 1-bit digital voltage sampling signal according to the reference clock signal output by the control circuit 400, acquires the 1-bit digital current sampling signal according to the reference clock signal output by the control circuit 400, outputs the 1-bit digital voltage sampling signal through a hardware pin voltage channel ADC sampling signal output terminal ADC _ UOUT of the single-phase metering chip U1, and outputs the 1-bit digital current sampling signal through a hardware pin current channel ADC sampling signal output terminal ADC _ IOUT of the single-phase metering chip U1.

Because the analog voltage sampling signal and the analog current sampling signal of three-phase four-wire are through single-phase measurement chip U1 collection back, through the sampling frequency of single-phase measurement chip U1's hardware pin voltage channel ADC sampling signal output ADC _ OUT and current channel ADC sampling signal output ADC _ IOUT with megaclock data stream, real-time transmission handles in control circuit 400, signal acquisition and processing have the real-time, the error that the electric energy measurement brought is given in the time delay of having avoided prior art's electric energy meter communication itself, and the electric energy metering error that the response untimely leads to when having avoided user's load rapid change.

In one embodiment, the model of the single-phase metering chip U1 is preferably RN8207D, and preferably, the frequency of the clock data stream is greater than or equal to 2M. Preferably, the single-phase metering chip U1 has any one of 1-fold, 2-fold, 4-fold, 8-fold, or 16-fold magnification.

In one embodiment, isolator assembly a 321, isolator assembly B322, isolator assembly C323, and neutral isolator assembly 324 comprise isolator modules including capacitively coupled isolator U2.

As shown in fig. 8, the first input terminal INA of the capacitive coupling isolator U2 is used as a digital voltage sampling signal input terminal of the single-phase voltage of the isolation module, and is connected to the single-phase metering component to receive the digital voltage sampling signal of the single-phase voltage.

The second input end INB of the capacitively coupled isolator U2 serves as a digital current sampling signal input end of the single-phase current of the isolation module, and is connected to the single-phase metering component to access the digital current sampling signal of the single-phase current or the digital current sampling signal of the neutral current.

The first output terminal OUTA of the capacitive coupling isolator U2 is used as a digital voltage sampling signal output terminal of the single-phase voltage of the isolation module, and is connected to the control circuit 400 to output a digital voltage sampling signal of the single-phase voltage.

The second output terminal OUTB of the capacitive coupling isolator U2 is used as a digital current sampling signal output terminal of the single-phase current of the isolation module, and is connected to the control circuit 400 to output a digital current sampling signal of the single-phase current or a digital current sampling signal of the neutral current.

The third input terminal INC of the capacitive coupling isolator U2 serves as a reference clock signal input terminal of the isolation module, and is connected to the control circuit 400 to receive the reference clock signal.

And a third output end OUTC of the capacitive coupling isolator U2 is used as a reference clock signal output end of the isolation module and is connected with the single-phase metering assembly so as to output the reference clock signal after capacitive coupling isolation.

It should be noted that the first input terminal INA of the capacitive coupling isolator U2 is connected to the digital voltage sampling signal of the single-phase voltage transmitted from the voltage channel ADC sampling signal output terminal ADC _ UOUT of the single-phase metering chip U1, and then the first output terminal OUTA of the capacitive coupling isolator U2 outputs the digital voltage signal U _1bit _inof 1bit of the single-phase voltage; the second input end INB of the capacitive coupling isolator U2 is connected with a digital current sampling signal of single-phase current or a digital current sampling signal of center line current transmitted by the current channel ADC sampling signal output end ADC _ IOUT of the single-phase metering chip U1, then, a 1bit digital current signal I _1bit _INof single-phase current or neutral current is output through a second output end OUTB of the capacitive coupling isolator U2; the third input terminal INC of the capacitive coupling isolator U2 is connected to the reference clock signal transmitted by the control circuit 400, and then outputs the reference clock signal after capacitive coupling isolation through the third output terminal OUTC of the capacitive coupling isolator U2.

Taking the phase a as an example, by setting the capacitive coupling isolation module, the electrical isolation among the phase a voltage detection component 110, the phase a current detection component 210, the phase a metering component 311, and the control circuit 400 is realized, that is, the electrical isolation between the strong current input end of the analog sampling signal and the weak current output end of the digital sampling signal is realized, at this time, the control circuit takes the weak current as the ground, the withstand voltage of the control circuit for controlling the strong current equipment by adopting the weak current signal is improved, and the safety of the electric energy metering circuit and the electric energy meter is improved. Preferably, the isolation voltage of the capacitively coupled isolation module is set to be greater than or equal to 5000V.

Because the capacitive coupling isolation module is arranged to efficiently transmit the digital current sampling signal, the digital voltage sampling signal and the reference clock signal in a capacitive coupling isolation mode, the transmission speed of a megaclock data stream of the electric energy metering circuit and the electric energy meter is realized, the digital current sampling signal and the digital voltage sampling signal can be transmitted to the control circuit in real time to be processed, the signal acquisition and processing have real-time performance, the error caused by the delay of the communication of the electric energy meter in the prior art to the electric energy metering is avoided, and the electric energy metering error caused by the untimely response when the load of a user is changed rapidly is avoided.

As shown in FIG. 9, in one embodiment, control circuit 400 includes a three-phase metering chip U3.

A first voltage external ADC input end VAN of the three-phase metering chip U3 is used as a digital voltage sampling signal input end of the A-phase voltage of the control circuit 400 and is connected with the metering circuit 300 so as to access the digital voltage sampling signal of the A-phase voltage; the second voltage external ADC input terminal VBN is used as a digital voltage sampling signal input terminal of the B-phase voltage of the control circuit 400, and is connected to the metering circuit 300 to access the digital voltage sampling signal of the B-phase voltage; the third voltage external ADC input terminal VCN is used as a digital voltage sampling signal input terminal of the C-phase voltage of the control circuit 400, and is connected to the metering circuit 300 to access the digital voltage sampling signal of the C-phase voltage.

A first current external ADC input end IA _ DIN of the three-phase metering chip U3 is used as an analog current sampling signal input end of the phase A current of the control circuit 400 and is connected with the metering circuit 300 so as to access a digital current sampling signal of the phase A current; the second current external ADC input terminal IB _ DIN is used as the digital current sampling signal input terminal of the phase B current of the control circuit 400, and is connected to the metering circuit 300 to access the digital current sampling signal of the phase B current; the third current external ADC input terminal IC _ DIN is used as the digital current sampling signal input terminal of the C-phase current of the control circuit 400, and is connected to the metering circuit 300 to access the digital current sampling signal of the C-phase current; the fourth external ADC input terminal IN _ DIN is used as a digital current sampling signal input terminal for the neutral current of the control circuit 400, and is connected to the metering circuit 300 for receiving the digital current sampling signal for the neutral current.

The external clock output terminal ADIN _ CKO of the three-phase metering chip U3 is used as the reference clock signal output terminal of the control circuit 400, and is connected to the metering circuit 300 to output the reference clock signal.

It should be noted that a first voltage external ADC input terminal VAN of the three-phase metering chip U3 is accessed to a 1-bit digital voltage sampling signal of an a-phase voltage, a second voltage external ADC input terminal VBN is accessed to a 1-bit digital voltage sampling signal of a B-phase voltage, a third voltage external ADC input terminal VCN is accessed to a 1-bit digital voltage sampling signal of a C-phase voltage, a first current external ADC input terminal IA _ DIN of the three-phase metering chip U3 is accessed to a 1-bit digital current sampling signal of an a-phase current, a second current external ADC input terminal IB _ DIN is accessed to a 1-bit digital current sampling signal of a B-phase current, a third current external ADC input terminal IC _ DIN is accessed to a 1-bit digital current sampling signal of a C-phase current, and a fourth current external ADC input terminal IN _ DIN is accessed to a 1-bit digital current sampling signal of a neutral current, and a digital signal processing module of the three-phase metering chip U3 performs an operation according to a preset calculation formula to output electrical parameters of a three-phase power grid, such as reactive power, an active power, a voltage active power factor, a current effective value, a phase angle, and the like. Meanwhile, the three-phase metering chip U3 also has the functions of waveform caching, zero-crossing detection, overvoltage and overcurrent detection, voltage sag detection, phase sequence detection and voltage line frequency detection.

In one embodiment, the model of the three-phase metering chip U3 is preferably RN8302C.

After the digital signals of all phases are transmitted to the digital signal processing module of the three-phase metering chip, the three-phase four-wire electric energy metering circuit can process electric energy metering in real time through hardware, accumulation operation and electric energy metering operation on the split-phase power in the prior art are not needed, software overhead is reduced, and operation time is shortened.

The electric energy metering circuit of three-phase four-wire of this embodiment has realized the electrical isolation between three-phase metering chip and the single-phase metering module through the isolation mode that sets up the capacitive coupling isolation module, and the three-phase metering chip uses weak current as ground this moment, has improved the safety that three-phase metering chip adopted weak current signal control forceful electric power equipment.

The three-phase four-wire electric energy metering circuit of this embodiment is through the single-phase measurement chip of 3 volume productions, with the collocation of the three-phase measurement chip of 1 volume productions, the cost is reduced. The clock of the 3 single-phase metering chips and the clock of the three-phase metering chip are kept synchronous, so that the A \ B \ C phases have a common clock reference on the clock, the phase angle, the electric energy and other parameter values can be directly obtained through the three-phase metering chip, and the calculation accuracy of the electric energy meter is improved. For example, when calculating the phase angle between the voltage and the current, a common phase may be selected, for example, the a-phase voltage UA is used as a clock reference, and the angular difference between UB/UC/IA/IB/IC and UA can be directly calculated.

In the electric energy meter in the prior art, because the single-phase metering chip and the three-phase metering chip read the split-phase power in a UART communication mode, and then calculate the phase-combining power, and the pulse is generated by calculating the phase-combining power, the calculated phase-combining power lags behind the actual power of the electric energy meter due to the restriction of the UART communication rate and the application program processing rate of the chip, and when the actual load power of a user changes, the calculated phase-combining power cannot obtain the real-time load power. In addition, when the electric energy meter repeatedly powers on and powers off, the pulse mantissa of the three-phase metering chip and the three-phase metering chip are difficult to obtain through communication. For example, the power data is read once in 1 second, and the prior art power meter defaults to the 1 second, in which the power of the load is stable, but the actual load operation is not ideal stable operation. Therefore, when the load changes, or the electric energy calculated by the three-phase metering chip in the power-up and power-down processes of the electric energy meter has a large error with the actual load electric energy.

The electric energy meter adopting the electric energy metering circuit of the embodiment transmits the sampling data of the A \ B \ C phase single-phase metering chip to the three-phase metering chip through the data stream of the 1bit digital signal, thereby eliminating the calculation error caused by the communication mode when the load current fluctuates.

The electric energy meter adopting the electric energy metering circuit of the embodiment can also have the functions of harmonic analysis and full voltage loss.

The following further description of the embodiments shown in fig. 6 to 10 is made with reference to the working principle:

analog voltage signals of the A phase of the three-phase power grid pass through an A phase voltage detection component 110 comprising a voltage division resistor string to obtain analog voltage sampling signals of the A phase voltage; a positive analog voltage sampling signal VAP of the A-phase voltage enters a voltage channel positive analog input end V2P of a single-phase metering chip U1 of the A-phase metering component 311, a negative analog voltage sampling signal VAN of the A-phase voltage enters a voltage channel negative analog input end V2N of the A-phase metering component 311, the analog voltage sampling signal of the A-phase voltage is amplified through the single-phase metering chip U1 and converted into a 1bit digital voltage sampling signal; the single-phase metering chip U1 receives a reference clock signal which is transmitted by a three-phase metering chip U3 of the control circuit 400 through a capacitive coupling isolator U2 of an A phase isolation assembly 321 after capacitive coupling isolation, a clock of the single-phase metering chip U1 and a clock of the three-phase metering chip U3 keep synchronous, and a 1bit digital voltage sampling signal is acquired according to the reference clock signal; a 1bit digital voltage sampling signal UA _1bit _OUTis output from a voltage channel ADC sampling signal output end ADC _ UOUT end of the single-phase metering chip U1 and is transmitted to a first input end INA of a capacitive coupling isolator U2 of an A isolation component 321; a first output end OUTA of the capacitive coupling isolator U2 outputs a 1-bit digital voltage sampling signal UA _1bit _INafter capacitive coupling isolation; the 1-bit digital voltage sampling signal UA _1bit _INis subjected to resistance-capacitance filtering and then converted into a 1-bit digital voltage sampling signal UA _1bit (a filter circuit is not shown in the figure), and the 1-bit digital voltage sampling signal UA _1bit is input from a first voltage external ADC input end VAN of the three-phase metering chip U3.

The analog current signal of the phase A of the three-phase power grid is converted into an analog voltage signal through a phase A current detection component 210 comprising a manganese copper sheet, and an analog current sampling signal of the phase A current is obtained, so that the analog current sampling signal of the phase A current is an analog voltage signal; a positive analog current sampling signal IAP of the A-phase current enters a current channel positive analog input end V1P of a single-phase metering chip U1 of the A-phase metering component 311, a negative analog current sampling signal IAN of the A-phase current enters a current channel negative analog input end V1N of the single-phase metering chip U1 of the A-phase metering component 311, and the analog current sampling signal of the A-phase current is amplified by the single-phase metering chip and converted into a 1bit digital current sampling signal; the single-phase metering chip U1 receives a reference clock signal which is subjected to capacitive coupling isolation and transmitted by a three-phase metering chip U3 of the control circuit 400 through a capacitive coupling isolator U2 of an A phase isolation assembly 321, a clock of the single-phase metering chip U1 and a clock of the three-phase metering chip U3 keep synchronous, and a 1-bit digital current sampling signal is acquired according to the reference clock signal; a 1bit digital current sampling signal IA _1bit _OUTis output from a current channel ADC sampling signal output end ADC _ IOUT of the single-phase metering chip U1 and is transmitted to a second input end INB of a capacitive coupling isolator U2 of an A isolation component 321; a second output end OUTB of the capacitive coupling isolator U2 outputs a capacitive coupling isolated 1-bit digital current sampling signal IA _1bit _IN; the 1-bit digital current sampling signal IA _1bit _INis converted into a 1-bit digital current sampling signal IA _1bit (a filter circuit is not shown in the figure) after the RC filtering, and is input from a first current external ADC input end IA _ DIN of the three-phase metering chip U3.

The sampling working process of the phase B and the phase C of the three-phase power grid is the same as that of the phase A, only current sampling is carried out on a neutral line of the three-phase power grid, and the working process is the same as that of the phase A.

A first voltage external ADC input end VAN of a three-phase metering chip U3 is accessed to a 1-bit digital voltage sampling signal UA _1bit of an A-phase voltage, a second voltage external ADC input end VBN is accessed to a 1-bit digital voltage sampling signal UB _1bit of a B-phase voltage, a third voltage external ADC input end VCN is accessed to a 1-bit digital voltage sampling signal UC _1bit of a C-phase voltage, a first current external ADC input end IA _ DIN of the three-phase metering chip U3 is accessed to a 1-bit digital current sampling signal IA _1bit of an A-phase current, a second current external ADC input end IB _ DIN is accessed to a 1-bit digital current sampling signal IB _1bit of a B-phase current, a third current external ADC input end IC _ DIN is accessed to a 1-bit digital current sampling signal IC _1bit of a C-phase current, a fourth current external ADC input end IN _1bit is accessed to a 1-bit digital current sampling signal IN _1bit of a DIN neutral current, the three-phase external ADC input end VAN receives the 1-bit digital voltage sampling signal and the digital current sampling signal IN _1bit of the three-phase voltage sampling signal, and a three-phase metering chip U3 outputs a digital electric energy calculation module according to a three-phase electric power grid calculation formula.

A second aspect of embodiments of the present application provides an electric energy meter including an electric energy metering circuit as described in any one of the above first aspects.

the embodiment of the application provides an electric energy metering circuit and an electric energy meter of a three-phase four-wire, each phase voltage of a three-phase power grid is detected through a voltage sampling circuit to output an analog voltage sampling signal, each phase current and a neutral line current of the three-phase power grid are detected through a current sampling circuit to output an analog current sampling signal, the metering circuit converts the analog voltage sampling signal into a digital voltage sampling signal according to a reference clock signal and converts the analog current sampling signal into a digital current sampling signal according to the reference clock signal, and a control circuit outputs the reference clock signal and calculates the digital voltage sampling signal of each phase voltage, the digital current sampling signal of each phase current and the digital current sampling signal of the neutral line to output electric parameters of the three-phase power grid; the digital current sampling signal and the digital voltage sampling signal are single-bit signals; the metering circuit and the control circuit are transmitted by adopting a single-bit signal, and the transmission speed is high, so that the three-phase combined power of the electric energy meter can reflect the actual use power of the current load in real time; and the metering circuit uses the same clock to convert the analog voltage sampling signal of each phase voltage, the analog current sampling signal of each phase current and the analog current sampling signal of the neutral line current, so that the A \ B \ C phases have a common clock reference on the clock in the clock phase, the parameter values such as phase angle and electric energy can be directly obtained through the control circuit, the calculation precision of the electric energy meter is improved, and the performance of the electric energy meter is improved.

Meanwhile, due to the integration of the functional modules, the cost of the electric energy meter is reduced, and the comprehensive actual requirements of the electric energy meter on functions, speed, power consumption, reliability, controllable cost and the like are met.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. A three-phase four-wire electric energy metering circuit, comprising:

the digital current sampling signal and the digital voltage sampling signal are single-bit signals;

wherein the voltage sampling circuit comprises: the device comprises an A phase voltage detection component, a B phase voltage detection component and a C phase voltage detection component; the current sampling circuit comprises an A-phase current detection component, a B-phase current detection component, a C-phase current detection component and a neutral current detection component; the metering circuit comprises an A-phase metering component, an A-phase isolation component, a B-phase metering component, a B-phase isolation component, a C-phase metering component, a C-phase isolation component, a neutral line metering component and a neutral line isolation component;

the A-phase voltage detection component is configured to detect an A-phase voltage to output an analog voltage sampling signal of the A-phase voltage; the B phase voltage detection component is configured to detect B phase voltage to output an analog voltage sampling signal of the B phase voltage; the C phase voltage detection component is configured to detect a C phase voltage to output an analog voltage sampling signal of the C phase voltage;

the A-phase current detection assembly is configured to detect A-phase current by adopting a manganin sheet so as to output an analog current sampling signal of the A-phase current; the phase B current detection component is configured to detect the phase B current by adopting a manganin sheet so as to output an analog current sampling signal of the phase B current; the C-phase current detection component is configured to detect the C-phase current by adopting a manganin sheet so as to output an analog current sampling signal of the C-phase current; the neutral current detection assembly is configured to detect the neutral current by adopting a manganin sheet so as to output an analog current sampling signal of the neutral current;

the A-phase metering component is connected with the A-phase voltage detection component, the A-phase current detection component and the control circuit, and is configured to convert an analog voltage sampling signal of the A-phase voltage into a digital voltage sampling signal of the A-phase voltage according to the reference clock signal and convert an analog current sampling signal of the A-phase current into a digital current sampling signal of the A-phase current according to the reference clock signal; the phase A isolation component is connected between the phase A metering component and the control circuit and is configured to capacitively couple and isolate the digital voltage sampling signal of the phase A voltage and the digital current sampling signal of the phase A current;

the B-phase metering component is connected with the B-phase voltage detection component, the B-phase current detection component and the control circuit, and is configured to convert an analog voltage sampling signal of the B-phase voltage into a digital voltage sampling signal of the B-phase voltage according to the reference clock signal and convert an analog current sampling signal of the B-phase current into a digital current sampling signal of the B-phase current according to the reference clock signal; the phase B isolation component is connected between the phase B metering component and the control circuit and is configured to capacitively couple and isolate the digital voltage sampling signal of the phase B voltage and the digital current sampling signal of the phase B current;

the C-phase metering component is connected with the C-phase voltage detecting component, the C-phase current detecting component and the control circuit, and is configured to convert an analog voltage sampling signal of the C-phase voltage into a digital voltage sampling signal of the C-phase voltage according to the reference clock signal and convert an analog current sampling signal of the C-phase current into a digital current sampling signal of the C-phase current according to the reference clock signal; the C phase isolating component is connected between the C phase metering component and the control circuit and is configured to capacitively couple and isolate the digital voltage sampling signal of the C phase voltage and the digital current sampling signal of the C phase current;

the neutral line metering component is connected with the neutral current detection component and the control circuit and is configured to convert an analog current sampling signal of the neutral current into a digital current sampling signal of the neutral current according to the reference clock signal; the neutral isolation assembly is connected between the neutral metering assembly and the control circuit and is configured to capacitively couple and isolate the digital current sampling signal of the neutral.

2. The electric energy metering circuit of claim 1, wherein the a-phase voltage detection assembly, the B-phase voltage detection assembly and the C-phase voltage detection assembly each comprise a voltage detection module, and the voltage detection module comprises a resistor string composed of n resistors, a first resistor, a second resistor, a first capacitor and a second capacitor, wherein n is a positive integer and n ≧ 1;

3. The electric energy metering circuit of claim 1, wherein the a-phase current detecting component, the B-phase current detecting component, the C-phase current detecting component and the neutral current detecting component each comprise a current detecting module, and the current detecting module comprises a manganese copper sheet, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor and a fourth capacitor;

4. The electrical energy metering circuit of claim 1, wherein the a-phase metering component, the B-phase metering component, the C-phase metering component, and the neutral metering component each comprise a metering module comprising a single-phase metering chip;

5. The electrical energy metering circuit of claim 1, wherein the phase a isolation assembly, the phase B isolation assembly, the phase C isolation assembly, and the neutral isolation assembly comprise isolation modules; the isolation module comprises a capacitive coupling isolator;

6. An electric energy metering circuit as claimed in any one of claims 1 to 5, wherein the control circuit comprises a three-phase metering chip;

7. An electric energy meter comprising the electric energy metering circuit according to any one of claims 1 to 6.