Electric energy metering circuit

Abstract

The utility model provides an electric energy metering circuit. The electric energy metering circuit comprises L1, L2 and L3 line voltage acquisition circuits, a neutral line voltage acquisition circuit, L1, L2 and L3 line current acquisition circuits and an electric energy metering chip MCU. For any voltage acquisition circuit, a current-limiting resistor is connected in series between an input pin of the first variable gain operational amplifier and the voltage acquisition interface; the first matching resistor is connected in series between the input pin and the reference voltage pin of the amplifier; for any current acquisition circuit, the primary side of the current transformer is connected in series between the two ends of the corresponding current acquisition interface, the secondary side of the current transformer is connected in series between the input pin and the reference voltage pin of the second variable gain operational amplifier, and the second matching resistor is connected in parallel with the secondary side of the current transformer. The electric energy metering chip MCU carries out electric energy metering according to the collected voltage and current data. Therefore, according to the scheme, larger signals can be acquired, and the acquisition accuracy of the signals is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of electric energy detection and measurement, and more particularly to an electric energy measurement circuit. BACKGROUND

[0002] At present, the power consumption increases with the explosive growth of electrical equipment, and how to accurately count the consumed electric energy is an important research topic. Electric energy statistics not only apply to electric energy consumption, but also can be applied to electric power detection in power generation and other industries, as well as supporting products of related equipment around electric power.

[0003] Early electric energy statistics mostly rely on analog circuits to measure current and voltage through current transformers (CT) and voltage transformers (VT). Modern electric energy statistics systems usually rely on microcontrollers for data acquisition and processing. The microcontroller acquires current and voltage signals through the built-in or external analog-to-digital converter (ADC), and then calculates the power and electric energy.

[0004] In the prior art, the Chinese utility model patent with publication number CN 216285478 U discloses a single-phase electric energy meter circuit, which includes a sampling module for acquiring analog input current and voltage signals, a signal amplification module for amplifying the transmitted analog signals, a SOC metering chip for digitizing the amplified analog signals, a liquid crystal display module for displaying the data parameters processed by the SOC metering chip, a data storage module for storing the data parameters processed by the SOC metering chip, a key module for viewing parameters and inputting setting signals, an electric energy pulse module for outputting electric energy pulses, an indicator light module for reminding users to purchase electricity in time, a relay drive module for controlling the disconnection, a communication module for communication with other external devices, and an IC card interface for users to purchase electricity according to actual needs. The single-phase electric energy meter circuit realizes accurate measurement of small signals by using a high-precision current transformer, but due to the use of single-range sampling, it cannot collect large signals, i.e. the problem of over-range collection occurs during collection, and secondly, the accuracy of signal collection is low.

[0005] In order to solve the above problems, people have been seeking an ideal technical solution. SUMMARY

[0006] The utility model aims at the shortage of prior art, and provides an electric energy measurement circuit to solve the problem of unable to collect large signals and improve the accuracy of signal collection.

[0007] In order to achieve the above object, the utility model provides a kind of electric energy measurement circuit, comprising: voltage acquisition circuit for collecting L1, L2 and L3 line voltage respectively, voltage acquisition circuit for collecting neutral line voltage, current acquisition circuit for collecting L1, L2 and L3 line current respectively, electric energy measurement chip MCU;

[0008] Any voltage acquisition circuit includes current-limiting resistance, first matching resistance and first variable gain operational amplifier;Current-limiting resistance is connected in series between the input pin CH0 of first variable gain operational amplifier and corresponding voltage acquisition interface;First matching resistance is connected in series between the input pin CH0 of first variable gain operational amplifier and the reference voltage pin Vref of first variable gain operational amplifier, and the reference voltage pin Vref of first variable gain operational amplifier is connected to first reference voltage source;The output pin Vout of first variable gain operational amplifier is connected to the signal input pin of electric energy measurement chip MCU;

[0009] Any current acquisition circuit includes current transformer, second matching resistance and second variable gain operational amplifier;The primary side of current transformer is connected in series between the two ends of corresponding current acquisition interface, the secondary side of current transformer is connected in series between the input pin CH0 of second variable gain operational amplifier and the reference voltage pin Vref of second variable gain operational amplifier, the reference voltage pin Vref of second variable gain operational amplifier is connected to second reference voltage source, and second matching resistance is connected in parallel with the secondary side of current transformer;The output pin Vout of second variable gain operational amplifier is connected to the signal input pin of electric energy measurement chip MCU;

[0010] The electric energy measurement chip MCU performs electric energy measurement according to the voltage collected by the voltage acquisition circuit and the current collected by the current acquisition circuit.

[0011] Compared with single-range sampling, the PGA variable gain operational amplifier of the utility model has multiple different amplification intervals, whether it is a larger signal or a smaller signal has a corresponding amplification interval, wherein the larger signal corresponds to a smaller amplification factor, and the smaller signal corresponds to a larger amplification factor, which can collect larger signals, and because the appropriate amplification factor can be selected according to the size of the signal, the signal acquisition accuracy is improved, and the collected signal is more accurate. Based on the more accurate voltage data and current data collected, more accurate consumed or produced electric energy can be calculated. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is the flowchart of the voltage acquisition circuit of the utility model;

[0013] Figure 2 is the circuit principle schematic diagram of the voltage acquisition circuit of the utility model;

[0014] Figure 3 is the flow schematic diagram of the current acquisition circuit of the utility model;

[0015] Figure 4 is the circuit principle schematic diagram of the current acquisition circuit of the utility model. DETAILED DESCRIPTION

[0016] The technical solutions of the utility model will be described in further detail below through specific embodiments.

[0017] The terms "first", "second", "third", "fourth" and the like in the description, claims, and drawings of the application are used to distinguish similar objects, and do not necessarily have to be used to describe a particular order or sequence. It should be understood that the terms used in this way can be interchanged under appropriate circumstances, and this is only a way of distinguishing similar objects in the description of the embodiments of the application.

[0018] Embodiment 1

[0019] As shown in the accompanying drawings, Figure 1 The voltage signals of the L1, L2 and L3 lines and the voltage signal of the neutral line of the utility model are amplified by the PGA (Programmable Gain Amplifier) variable gain operational amplifier respectively, and the amplified voltage signals are input into the electric energy metering chip MCU for analysis and processing. Among them, higher voltage corresponds to smaller amplification, and lower voltage corresponds to larger amplification. Further, more accurate voltage signals can be obtained.

[0020] As shown in the accompanying drawings, Figure 3 The current signals of the L1, L2 and L3 lines of the utility model are sequentially input into the current transformer and the PGA variable gain operational amplifier, and the amplified signals are input into the electric energy metering chip MCU for analysis and processing. Among them, larger current corresponds to smaller amplification, and smaller current corresponds to larger amplification. Further, more accurate current signals can be obtained.

[0021] Further, more accurate consumed or produced electric energy can be obtained through the calculation and processing of the electric energy metering chip MCU.

[0022] As shown in the accompanying drawings, Figure 2 The embodiment gives a specific embodiment of the voltage acquisition circuit.

[0023] An electric energy metering circuit comprises: voltage acquisition circuits for acquiring L1, L2 and L3 line voltages respectively, a voltage acquisition circuit for acquiring a neutral line voltage, current acquisition circuits for acquiring L1, L2 and L3 line currents respectively, and an electric energy metering chip MCU;

[0024] The voltage acquisition circuit of the L1 line comprises:

[0025] The voltage acquisition interface of the L1 line is connected with a first current-limiting resistor R2, a second current-limiting resistor R3, a third current-limiting resistor R4, a first patch magnetic bead L1 and an input pin CH0 of a first variable gain operational amplifier U1 in sequence.

[0026] A first matching resistor R5 is connected in series between the input pin CH0 of the first variable gain operational amplifier U1 and a reference voltage pin Vref of the first variable gain operational amplifier U1, the reference voltage pin Vref of the first variable gain operational amplifier U1 is connected with a first reference voltage source, and an output pin Vout of the first variable gain operational amplifier U1 is connected with a first signal input pin of the electric energy metering chip MCU.

[0027] The output pin Vout of the first variable gain operational amplifier U1 is connected with a first filter capacitor C1 and then grounded.

[0028] A positive supply pin VDD of the first variable gain operational amplifier U1 is connected with a second filter capacitor C2 and then grounded, and the positive supply pin VDD of the first variable gain operational amplifier U1 is connected with a first power supply voltage source.

[0029] The input pin CH0 of the first variable gain operational amplifier U1 is connected with a third filter capacitor C3 and then grounded.

[0030] A chip select pin CS of the first variable gain operational amplifier U1 is connected with an input / output pin of the electric energy metering chip MCU.

[0031] It should be noted that the first filter circuit of the voltage acquisition circuit of the L1 line comprises the first patch magnetic bead L1 and the third filter capacitor C3.

[0032] The voltage acquisition circuit of the L2 line comprises:

[0033] The voltage acquisition interface of the L2 line is connected with a first current-limiting resistor R7, a second current-limiting resistor R8, a third current-limiting resistor R9, a first patch magnetic bead L2 and an input pin CH0 of a first variable gain operational amplifier U2 in sequence.

[0034] The first matching resistor R10 is connected in series between the input pin CH0 of the first variable gain operational amplifier U2 and the reference voltage pin Vref of the first variable gain operational amplifier U2, and the reference voltage pin Vref of the first variable gain operational amplifier U2 is connected to the first reference voltage source; and the output pin Vout of the first variable gain operational amplifier U2 is connected to the first signal input pin of the electric energy metering chip MCU.

[0035] The output pin Vout of the first variable gain operational amplifier U2 is connected to the first filter capacitor C4 and then grounded.

[0036] The positive supply pin VDD of the first variable gain operational amplifier U2 is connected to the second filter capacitor C5 and then grounded, and the positive supply pin VDD of the first variable gain operational amplifier U2 is connected to the first power supply voltage source.

[0037] The input pin CH0 of the first variable gain operational amplifier U2 is connected to the third filter capacitor C6 and then grounded.

[0038] The chip select pin CS of the first variable gain operational amplifier U2 is connected to the input / output pin of the electric energy metering chip MCU.

[0039] The voltage acquisition circuit of the L3 line:

[0040] The voltage acquisition interface of the L3 line is connected in sequence to the first current limiting resistor R12, the second current limiting resistor R13, the third current limiting resistor R14, the first patch magnetic bead L3, and the input pin CH0 of the first variable gain operational amplifier U3.

[0041] The first matching resistor R15 is connected in series between the input pin CH0 of the first variable gain operational amplifier U3 and the reference voltage pin Vref of the first variable gain operational amplifier U3, and the reference voltage pin Vref of the first variable gain operational amplifier U3 is connected to the first reference voltage source; and the output pin Vout of the first variable gain operational amplifier U3 is connected to the first signal input pin of the electric energy metering chip MCU.

[0042] The output pin Vout of the first variable gain operational amplifier U3 is connected to the first filter capacitor C7 and then grounded.

[0043] The positive supply pin VDD of the first variable gain operational amplifier U3 is connected to the second filter capacitor C8 and then grounded, and the positive supply pin VDD of the first variable gain operational amplifier U3 is connected to the first power supply voltage source.

[0044] The input pin CH0 of the first variable gain operational amplifier U3 is connected to the third filter capacitor C9 and then grounded.

[0045] The chip select pin CS of the first variable gain operational amplifier U3 is connected to the input / output pin of the power metering chip MCU.

[0046] Neutral line voltage acquisition circuit:

[0047] The voltage acquisition interface of the neutral line is connected in sequence to the first current limiting resistor R17, the second current limiting resistor R18, the third current limiting resistor R19, the first surface-mount ferrite bead L4, and the input pin CH0 of the first variable gain operational amplifier U4;

[0048] The first matching resistor R20 is connected in series between the input pin CH0 of the first variable gain operational amplifier U4 and the reference voltage pin Vref of the first variable gain operational amplifier U4. The reference voltage pin Vref of the first variable gain operational amplifier U4 is connected to the first reference voltage source. The output pin Vout of the first variable gain operational amplifier U4 is connected to the first signal input pin of the power metering chip MCU.

[0049] The output pin Vout of the first variable gain operational amplifier U4 is connected to the first filter capacitor C10 and then grounded.

[0050] The positive power supply pin VDD of the first variable gain operational amplifier U4 is connected to the second filter capacitor C11 and then grounded. The positive power supply pin VDD of the first variable gain operational amplifier U4 is connected to the first power supply voltage source.

[0051] The input pin CH0 of the first variable gain operational amplifier U4 is connected to the third filter capacitor C12 and then grounded;

[0052] The chip select pin CS of the first variable gain operational amplifier U4 is connected to the input / output pin of the power metering chip MCU.

[0053] It should be noted that the voltage of the first power supply source is 3.3 volts.

[0054] It should also be noted that after each voltage path passes through a current-limiting resistor, it is filtered and then passed through a matching resistor to obtain a voltage signal. The PGA (Variable Gain) operational amplifier can identify and amplify this voltage signal. The PGA has multiple different amplification ranges, corresponding to both higher and lower voltages. Higher voltages correspond to lower amplification factors, and lower voltages correspond to higher amplification factors. Based on this, this invention can acquire a wider range of voltage data, including higher voltage data, solving the problem of being unable to acquire higher voltage signals, i.e., the problem of exceeding the acquisition range. Secondly, because an appropriate amplification factor can be selected according to the magnitude of the voltage data, the acquisition accuracy of the voltage data is improved, making the acquired voltage data more accurate.

[0055] likeFigure 4 As shown in the figure, this embodiment provides a specific implementation method for the current acquisition circuit.

[0056] L1 line current acquisition circuit:

[0057] The primary winding of current transformer TC1 is connected in series between current acquisition interfaces TC1_S1 and TC1_S2. The secondary winding of current transformer TC1 is connected in series between the input pin CH0 of the second variable gain operational amplifier U1 and the reference voltage pin Vref of the second variable gain operational amplifier U1. The reference voltage pin Vref of the second variable gain operational amplifier U1 is connected to the second reference voltage source. The second matching resistor R1 is connected in parallel with the secondary winding of current transformer TC1. The output pin Vout of the second variable gain operational amplifier U1 is connected to the second signal input pin of the energy metering chip MCU.

[0058] One end of the secondary side of the current transformer TC1 is connected in series with the second surface mount bead L1 and then connected to the input pin CH0 of the second variable gain operational amplifier U1. The other end is connected in series with the third surface mount bead L2 and then connected to the reference voltage pin Vref of the second variable gain operational amplifier U1.

[0059] The output pin Vout of the second variable gain operational amplifier U1 is connected to the fourth filter capacitor C1 and then grounded.

[0060] The positive power supply pin VDD of the second variable gain operational amplifier U1 is connected to the fifth filter capacitor C2 and then grounded. The positive power supply pin VDD of the second variable gain operational amplifier U1 is connected to the second power supply voltage source.

[0061] The input pin CH0 of the second variable gain operational amplifier U1 is connected to the sixth filter capacitor C3 and then grounded;

[0062] The seventh filter capacitor C4 is connected in parallel with the second matching resistor;

[0063] The reference voltage pin Vref of the second variable gain operational amplifier U1 is connected to the eighth filter capacitor C5 and then grounded.

[0064] The chip select pin CS of the second variable gain operational amplifier U1 is connected to the input / output pin of the power metering chip MCU.

[0065] It should be noted that the second LC filter circuit of the current acquisition circuit of L1 line includes the second surface mount ferrite bead L1, the third surface mount ferrite bead L2, the sixth filter capacitor C3, and the eighth filter capacitor C5.

[0066] L2 line current acquisition circuit:

[0067] The primary winding of current transformer TC2 is connected in series between current acquisition interfaces TC2_S1 and TC2_S2. The secondary winding of current transformer TC2 is connected in series between the input pin CH0 of the second variable gain operational amplifier U2 and the reference voltage pin Vref of the second variable gain operational amplifier U2. The reference voltage pin Vref of the second variable gain operational amplifier U2 is connected to the second reference voltage source. The second matching resistor R2 is connected in parallel with the secondary winding of current transformer TC2. The output pin Vout of the second variable gain operational amplifier U2 is connected to the second signal input pin of the energy metering chip MCU.

[0068] One end of the secondary side of the current transformer TC2 is connected in series with the second surface mount bead L3 and then connected to the input pin CH0 of the second variable gain operational amplifier U2. The other end is connected in series with the third surface mount bead L4 and then connected to the reference voltage pin Vref of the second variable gain operational amplifier U2.

[0069] The output pin Vout of the second variable gain operational amplifier U2 is connected to the fourth filter capacitor C6 and then grounded.

[0070] The positive power supply pin VDD of the second variable gain operational amplifier U2 is connected to the fifth filter capacitor C7 and then grounded. The positive power supply pin VDD of the second variable gain operational amplifier U2 is connected to the second power supply voltage source.

[0071] The input pin CH0 of the second variable gain operational amplifier U2 is connected to the sixth filter capacitor C8 and then grounded;

[0072] The seventh filter capacitor C9 is connected in parallel with the second matching resistor;

[0073] The reference voltage pin Vref of the second variable gain operational amplifier U2 is connected to the eighth filter capacitor C10 and then grounded;

[0074] The chip select pin CS of the second variable gain operational amplifier U2 is connected to the input / output pin of the power metering chip MCU.

[0075] L3 line current acquisition circuit:

[0076] The primary winding of current transformer TC3 is connected in series between current acquisition interfaces TC3_S1 and TC3_S2. The secondary winding of current transformer TC3 is connected in series between the input pin CH0 of the second variable gain operational amplifier U3 and the reference voltage pin Vref of the second variable gain operational amplifier U3. The reference voltage pin Vref of the second variable gain operational amplifier U3 is connected to the second reference voltage source. The second matching resistor R3 is connected in parallel with the secondary winding of current transformer TC3. The output pin Vout of the second variable gain operational amplifier U3 is connected to the second signal input pin of the energy metering chip MCU.

[0077] One end of the secondary side of the current transformer TC3 is connected in series with the second surface mount bead L5 and then connected to the input pin CH0 of the second variable gain operational amplifier U3. The other end is connected in series with the third surface mount bead L6 and then connected to the reference voltage pin Vref of the second variable gain operational amplifier U3.

[0078] The output pin Vout of the second variable gain operational amplifier U3 is connected to the fourth filter capacitor C11 and then grounded.

[0079] The positive power supply pin VDD of the second variable gain operational amplifier U3 is connected to the fifth filter capacitor C12 and then grounded. The positive power supply pin VDD of the second variable gain operational amplifier U3 is connected to the second power supply voltage source.

[0080] The input pin CH0 of the second variable gain operational amplifier U3 is connected to the sixth filter capacitor C13 and then grounded;

[0081] The seventh filter capacitor C14 is connected in parallel with the second matching resistor;

[0082] The reference voltage pin Vref of the second variable gain operational amplifier U3 is connected to the eighth filter capacitor C15 and then grounded.

[0083] The chip select pin CS of the second variable gain operational amplifier U3 is connected to the input / output pin of the power metering chip MCU.

[0084] It should be noted that the input / output pins of the power metering chip MCU can be ordinary I / O pins; the first signal input pin and the second signal input pin of the power metering chip MCU are ADC detection pins; the voltage of the second power supply voltage source is 3.3 volts; the VSS pin of the variable gain operational amplifier is grounded; the other peripheral circuits of the variable gain operational amplifier are well known to those skilled in the art and will not be described in detail.

[0085] It should also be noted that after each current flows through a current transformer and is filtered, it passes through a matching resistor to obtain a voltage signal. The PGA (Variable Gain) operational amplifier can identify and amplify this voltage signal. The PGA has multiple different amplification ranges, corresponding to both large and small currents. Larger currents correspond to smaller amplification factors, and smaller currents correspond to larger amplification factors. Based on this, this invention can acquire a wider range of current data, including larger current data, solving the problem of being unable to acquire large current signals, i.e., the problem of exceeding the acquisition range. Secondly, because an appropriate amplification factor can be selected according to the magnitude of the current data, the acquisition accuracy of the current data is improved, making the acquired current data more accurate.

[0086] The MCU (Microcontroller Unit) for energy metering can sequentially read voltage and current data from each circuit via a chip select program, enabling direct calculation of energy data for each circuit. Compared to using a separate machine to directly calculate the total energy of the three phases and then calculate the energy of each phase, the circuit in this embodiment can obtain energy data from one or more circuits as needed, allowing for calculation of energy data as required. For example, if only the energy of line L1 needs to be calculated, the energy data of line L1 can be calculated solely based on the collected current and voltage data, and the obtained energy data is more accurate.

[0087] Based on the collected current and voltage data, the energy metering chip MCU can calculate the consumed or produced electrical energy. Because current and voltage data are more accurate, the calculated electrical energy is also more precise.

[0088] In some embodiments, the variable gain operational amplifier is model MCP6S91.

[0089] To ensure the stable operation and provide a guarantee for the power system, and to provide strong data support for the entire system, the power metering circuit of this utility model can work in relatively complex environments.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it; although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this utility model or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the technical solution claimed by this utility model.

Claims

1. An electrical energy metering circuit, characterized by The application relates to an electric energy metering circuit. Any voltage acquisition circuit comprises a current-limiting resistor, a first matching resistor and a first variable gain operational amplifier; the current-limiting resistor is connected in series between an input pin CH0 of the first variable gain operational amplifier and a corresponding voltage acquisition interface; the first matching resistor is connected in series between the input pin CH0 of the first variable gain operational amplifier and a reference voltage pin Vref of the first variable gain operational amplifier, and the reference voltage pin Vref of the first variable gain operational amplifier is connected to a first reference voltage source; an output pin Vout of the first variable gain operational amplifier is connected to a signal input pin of an electric energy metering chip MCU; Any current acquisition circuit comprises a current transformer, a second matching resistor and a second variable gain operational amplifier; a primary side of the current transformer is connected in series between two ends of a corresponding current acquisition interface, a secondary side of the current transformer is connected in series between an input pin CH0 of the second variable gain operational amplifier and a reference voltage pin Vref of the second variable gain operational amplifier, the reference voltage pin Vref of the second variable gain operational amplifier is connected to a second reference voltage source, and the second matching resistor is connected in parallel with the secondary side of the current transformer; an output pin Vout of the second variable gain operational amplifier is connected to a signal input pin of the electric energy metering chip MCU. The electric energy metering chip MCU performs electric energy metering according to the voltage acquired by the voltage acquisition circuit and the current acquired by the current acquisition circuit. Any voltage acquisition circuit further comprises a first LC filter circuit.

2. An electrical energy metering circuit according to claim 1, characterised in that, The first LC filter circuit is connected between the input pin CH0 of the first variable gain operational amplifier and the corresponding voltage acquisition interface. A chip select pin CS of the first variable gain operational amplifier is connected to an input / output pin of the electric energy metering chip MCU.

3. An electrical energy metering circuit according to claim 2, characterised in that: Any current acquisition circuit further comprises a second LC filter circuit.

4. An electrical energy metering circuit according to claim 1, characterized in that: The second LC filter circuit is connected between the input pin CH0 of the second variable gain operational amplifier and the secondary side of the current transformer.

5. The electric energy metering circuit according to claim 4, characterized in that: A chip select pin CS of the second variable gain operational amplifier is connected to an input / output pin of the electric energy metering chip MCU. The model of the operational amplifier is MCP6S91.

6. An electrical energy metering circuit according to any one of claims 1 to 5, characterized in that: ​

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