Ammeter circuit for suppressing damped oscillation wave and intelligent ammeter

Abstract

The invention is suitable for the technical field of electricity meters, and designs an electricity meter circuit for suppressing damped oscillation waves and an intelligent electricity meter. According to the circuit, high-frequency noise is absorbed through magnetic beads and an RC filter circuit, the winding mode of a high-frequency transformer is changed, and the inductance value is modified, the transformer forms a magnetic core shielding winding, a primary winding, a shielding winding, a main circuit winding, an auxiliary circuit winding and a VCC winding in a forward winding mode, the magnetic core shielding winding and the primary winding are opposite, and the winding starting point is connected to a static point. The number of turns of the magnetic core shielding winding and the number of turns of the primary winding are a preset ratio, the magnetic core shielding winding, the primary winding, the shielding winding and the VCC winding are arranged on the primary side of the transformer, the main winding and the auxiliary winding are arranged on the secondary side of the transformer, the main winding is connected with a main circuit for power supply, and the auxiliary winding is connected with an auxiliary circuit for power supply. And a coupling path formed by a damping oscillation wave signal entering the metering chip, the transformer and the ground along a voltage line is eliminated, so that error jump caused by damping oscillation conversion peak is inhibited.

Description

Technical Field

[0001] The present application is applicable to the technical field of electric meters, and in particular relates to an electric meter circuit and a smart electric meter for suppressing damped oscillation waves. Background Art

[0002] With the development of society, the power system has entered thousands of households. Every household has installed a smart meter to measure the electricity used. The accuracy of the meter directly affects the user experience and can avoid overbilling or underbilling. Therefore, when the smart meter is put into use, it is generally necessary to carry out a damped oscillation wave test. This test is applicable to electricity meters connected via voltage transformers. At present, when doing damped oscillation tests, smart meters will be affected in both differential mode 100KHZ and 1MHZ. The impact is manifested in a large error value at the switching moment. This error value is random and can be as large as exceeding the grid standard requirements.

[0003] Therefore, how to improve the circuit of the smart meter to suppress the error jump caused by the damped oscillation conversion spike has become an urgent problem to be solved. Summary of the invention

[0004] In view of this, the embodiments of the present application provide an electric meter circuit and a smart electric meter for suppressing damped oscillation waves, so as to solve the problem of how to improve the circuit of the smart electric meter to suppress error jumps caused by damped oscillation conversion spikes.

[0005] In a first aspect, an embodiment of the present application provides an electric meter circuit for suppressing damped oscillation waves, the electric meter circuit comprising a switching power supply and a transformer, the transformer adopts a forward winding to sequentially form a magnetic core shielding winding, a primary winding, a shielding winding, a main winding, an auxiliary winding and a VCC winding, the magnetic core shielding winding and the primary winding are in opposite directions and the starting point is connected to the static point of the switching power supply, the ratio of the number of turns of the magnetic core shielding winding to the number of turns of the primary winding is a preset value, and the preset value is less than 1; The magnetic core shielding winding, the primary winding, the shielding winding and the VCC winding are all arranged on the primary side of the transformer, the main winding and the auxiliary winding are both arranged on the secondary side of the transformer, the main winding is used to connect the 485 circuit, the carrier circuit, and the relay circuit of the electric meter for power supply, and the auxiliary winding is used to connect the MCU circuit, the metering circuit and the MCU peripheral circuit in the electric meter for power supply.

[0006] In one implementation, each layer of the primary winding, the main winding, the auxiliary winding and the VCC winding is tightly wound in one layer.

[0007] In one embodiment, the electric meter circuit further includes a first ADC voltage sampling circuit, a second ADC sampling circuit, and a third ADC sampling circuit, each ADC sampling circuit is grounded after passing through a first voltage-dividing resistor and a second voltage-dividing resistor, a filter capacitor is connected in parallel to the second voltage-dividing resistor, a first magnetic bead is arranged between the first voltage-dividing resistor and the second voltage-dividing resistor, and an output end of the corresponding ADC sampling circuit is led out between the first magnetic bead and the second voltage-dividing resistor; The input end of the first ADC voltage sampling circuit is used to connect the A-phase live wire of the electric meter, the output end of the first ADC voltage sampling circuit is used to connect the A-phase ADC voltage sampling terminal of the metering chip in the metering circuit, the input end of the second ADC voltage sampling circuit is used to connect the B-phase live wire of the electric meter, the output end of the second ADC voltage sampling circuit is used to connect the B-phase ADC voltage sampling terminal of the metering chip, the input end of the third ADC voltage sampling circuit is used to connect the C-phase live wire of the electric meter, and the output end of the third ADC voltage sampling circuit is used to connect the C-phase ADC voltage sampling terminal of the metering chip.

[0008] In one implementation, an RC circuit is connected in parallel to the second voltage-dividing resistor, and an output terminal of the corresponding ADC sampling circuit is connected between the resistor and the capacitor of the RC circuit.

[0009] In one embodiment, the first voltage-dividing resistor includes six 330KΩ resistors connected in series, and the second voltage-dividing resistor includes a 1KΩ resistor.

[0010] In one embodiment, the electric meter circuit further includes a neutral line grounding circuit, a second magnetic bead is arranged on the neutral line grounding circuit, one end of the second magnetic bead is used to connect the neutral line, and the other end of the second magnetic bead is grounded.

[0011] In one embodiment, the electric meter circuit further includes a metering chip power supply circuit, on which a third magnetic bead is arranged, one end of the third magnetic bead is connected to a voltage source, and the other end of the third magnetic bead is used to connect to the VCC terminal of the metering chip in the metering circuit.

[0012] In one embodiment, a first transistor is further provided on the power supply circuit of the metering chip, the control end of the first transistor is used to connect the control signal, the input end of the first transistor is connected to the third magnetic bead, and the output end of the first transistor is used to connect the VCC terminal of the metering chip in the metering circuit.

[0013] In one implementation, the preset value is 2 / 3.

[0014] In a second aspect, an embodiment of the present application provides a smart meter, the smart meter comprising a metering chip in a metering circuit and a meter circuit connected to the metering chip, the meter circuit comprising a switching power supply and a transformer, the transformer adopts a forward winding to sequentially form a magnetic core shielding winding, a primary winding, a shielding winding, a main winding, an auxiliary winding and a VCC winding, the magnetic core shielding winding and the primary winding are in opposite directions and the starting point is connected to the static point of the switching power supply, the ratio of the number of turns of the magnetic core shielding winding to the number of turns of the primary winding is a preset value, and the preset value is less than 1; The magnetic core shielding winding, the primary winding, the shielding winding and the VCC winding are all arranged on the primary side of the transformer, the main winding and the auxiliary winding are both arranged on the secondary side of the transformer, the main winding is used to connect the 485 circuit, the carrier circuit, and the relay circuit in the electric meter for power supply, and the auxiliary winding is used to connect the MCU circuit, the metering circuit and the MCU peripheral circuit of the electric meter.

[0015] In one implementation, each layer of the primary winding, the main winding, the auxiliary winding and the VCC winding is tightly wound in one layer.

[0016] In one embodiment, the electric meter circuit further includes a first ADC voltage sampling circuit, a second ADC sampling circuit, and a third ADC sampling circuit, each ADC sampling circuit is grounded after passing through a first voltage-dividing resistor and a second voltage-dividing resistor, a filter capacitor is connected in parallel to the second voltage-dividing resistor, a first magnetic bead is arranged between the first voltage-dividing resistor and the second voltage-dividing resistor, and an output end of the corresponding ADC sampling circuit is led out between the first magnetic bead and the second voltage-dividing resistor; The input end of the first ADC voltage sampling circuit is used to connect the A-phase live wire of the electric meter, the output end of the first ADC voltage sampling circuit is used to connect the A-phase ADC voltage sampling terminal of the metering chip in the metering circuit, the input end of the second ADC voltage sampling circuit is used to connect the B-phase live wire of the electric meter, the output end of the second ADC voltage sampling circuit is used to connect the B-phase ADC voltage sampling terminal of the metering chip, the input end of the third ADC voltage sampling circuit is used to connect the C-phase live wire of the electric meter, and the output end of the third ADC voltage sampling circuit is used to connect the C-phase ADC voltage sampling terminal of the metering chip.

[0017] In one implementation, an RC circuit is connected in parallel to the second voltage-dividing resistor, and an output terminal of the corresponding ADC sampling circuit is connected between the resistor and the capacitor of the RC circuit.

[0018] In one embodiment, the first voltage-dividing resistor includes six 330KΩ resistors connected in series, and the second voltage-dividing resistor includes a 1KΩ resistor.

[0019] In one embodiment, the electric meter circuit further includes a neutral line grounding circuit, a second magnetic bead is arranged on the neutral line grounding circuit, one end of the second magnetic bead is used to connect the neutral line, and the other end of the second magnetic bead is grounded.

[0020] In one embodiment, the electric meter circuit further includes a metering chip power supply circuit, on which a third magnetic bead is arranged, one end of the third magnetic bead is connected to a voltage source, and the other end of the third magnetic bead is used to connect to the VCC terminal of the metering chip in the metering circuit.

[0021] In one embodiment, a first transistor is further provided on the power supply circuit of the metering chip, the control end of the first transistor is used to connect the control signal, the input end of the first transistor is connected to the third magnetic bead, and the output end of the first transistor is used to connect the VCC terminal of the metering chip in the metering circuit.

[0022] In one implementation, the preset value is 2 / 3.

[0023] Compared with the prior art, the embodiments of the present application have the following beneficial effects: the electric meter circuit of the present application includes a switching power supply and a transformer, the transformer adopts a forward winding, and sequentially forms a magnetic core shielding winding, a primary winding, a shielding winding, a main winding, an auxiliary winding and a VCC winding, the magnetic core shielding winding and the primary winding are reversed and the starting point is connected to the static point of the switching power supply, the ratio of the number of turns of the magnetic core shielding winding to the number of turns of the primary winding is a preset value, the magnetic core shielding winding, the primary winding, the shielding winding and the VCC winding are all arranged on the primary side of the transformer, the main winding and the auxiliary winding are all arranged on the secondary side of the transformer, the main winding is used to connect the 485 circuit, the carrier circuit, and the relay circuit of the electric meter for power supply, and the auxiliary winding is used to connect the MCU circuit, the metering circuit and the MCU peripheral circuit in the electric meter for power supply. The above-mentioned setting can eliminate the damped oscillation wave signal entering the metering chip, the transformer and the earth along the voltage line to form a coupling path, and at the same time, the magnetic core shielding winding and the primary winding are reversed relative to the earth, and the current generated by these two windings can be offset, suppressing the damped oscillation conversion peak to cause error jump. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 It is a structural schematic diagram of an electric meter circuit for suppressing damped oscillation waves provided in the first embodiment of the present application; Figure 2It is a schematic diagram of the electrical principle and winding structure of a high-frequency transformer provided in Example 1 of the present application; Figure 3 This is a circuit diagram of a three-phase voltage positive electrode of a metering chip provided in Example 2 of the present application; Figure 4 This is a circuit diagram of a three-phase voltage negative pole of a metering chip provided in Example 2 of the present application; Figure 5 This is a circuit diagram of the positive and negative poles of a three-phase current of a metering chip provided in Example 2 of the present application; Figure 6 This is a connection diagram of a metering chip control circuit provided in Example 2 of the present application; Figure 7 This is a schematic diagram of a connection between a neutral line and a ground provided in Embodiment 3 of the present application; Figure 8 This is a connection diagram of a metering chip power supply circuit provided in Example 4 of the present application. DETAILED DESCRIPTION

[0026] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0027] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0028] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0029] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0030] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0031] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0032] It should be understood that the size of the serial numbers of the steps in the following embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0033] In order to illustrate the technical solution of the present application, a specific embodiment is provided below for illustration.

[0034] See also Figure 1 , is a structural schematic diagram of an electric meter circuit for suppressing damped oscillation waves provided in Example 1 of the present application, wherein the electric meter circuit includes a switching power supply and a transformer (i.e., T200), the transformer is wound in a forward direction, and a magnetic core shielding winding (i.e., N1), a primary winding (i.e., N2), a shielding winding (i.e., N3), a main winding (i.e., N4), an auxiliary winding (i.e., N5) and a VCC winding (i.e., N6) are formed in sequence, the magnetic core shielding winding and the primary winding are wound in opposite directions and the starting point is connected to the static point (bus high-voltage end) of the switching power supply, the ratio of the number of turns of the magnetic core shielding winding to the number of turns of the primary winding is a preset value, the preset value is less than 1, and in one embodiment, the preset value is 2 / 3.

[0035] The core shield winding, primary winding, shield winding and VCC winding are all set on the primary side of the transformer, the main winding and auxiliary winding are all set on the secondary side of the transformer, the main winding is used to connect the 485 circuit, carrier circuit, and relay circuit of the meter for power supply, and the auxiliary winding is used to connect the MCU circuit, metering circuit, and MCU peripheral circuits in the meter for power supply. The MCU peripheral circuit includes but is not limited to EEPROM and FLASH storage circuits, key circuits, LCD display circuits, far infrared circuits, and ESAM circuits. The MCU chip is also connected to other circuits in the meter to form a complete MCU circuit, and the metering circuit contains a metering chip.

[0036] Among them, the transformer output is divided into two paths, one is the main path (powering the 485 circuit, carrier circuit, and relay), and the other is the auxiliary path (powering the MCU circuit, metering circuit, and MCU peripheral circuit). Considering that the damped oscillation wave signal enters the meter along the input voltage line (three live wires and neutral wire), the damped oscillation wave signal enters the ADC sampling of the metering chip through three voltage resistors. At the same time, the damped oscillation wave signal goes along the rectifier filter at the input end of the flyback switching power supply to the transformer and then to the auxiliary power supply for voltage reduction, and finally enters the metering chip along the power supply to cause error jump. Therefore, it is necessary to consider attenuating and absorbing the damped oscillation wave signal at the source. The core shielding winding and the primary winding are reversed and the starting point is connected to the static point (bus high voltage end). The number of turns of the core shielding winding is 2 / 3 of the number of turns of the primary winding. The purpose of this is to eliminate the damped oscillation wave signal along the voltage line to enter the transformer and the earth to form a coupling path. At the same time, the core shielding winding and the primary winding are reversed relative to the earth, and the currents generated by these two windings can just offset each other.

[0037] The shielding winding is placed between the primary winding and the main winding in order to balance the electromotive force between the primary and main windings to reduce noise coupling, and also to prevent the damped oscillation wave signal from coupling through the primary winding to other windings and finally flowing to the metering chip to cause error jumps.

[0038] like Figure 2 As shown, it is a schematic diagram of the electrical principle and winding structure of a high-frequency transformer provided in Example 1 of the present application, wherein the winding is performed with reference to the winding sequence in Table 1 below, and the technical parameters of the inductance and leakage inductance under corresponding test conditions are referred to in Table 2 below.

[0039] Table 1 Table 2 In one embodiment, each layer of the main winding, the auxiliary winding and the VCC winding is tightly wound. Each layer of the main winding, the auxiliary winding and the VCC winding is tightly wound to ensure that the electromotive force between the windings and between each turn of the winding can offset each other, reducing the error jump caused by the noise flowing to the metering chip.

[0040] The transformer core uses EP15 and the material is PC95. The EP15 core is completely closed on the left and right and top to prevent the high-frequency noise inside the transformer from radiating to the PCB board and causing power jumps, thereby causing interference to the power supply of the metering chip and causing error jumps.

[0041] In this embodiment, the switching power supply is a flyback switching power supply, which has high reliability, simple circuit topology, complete electrical isolation between input and output, and can achieve multi-channel output to meet the application requirements of electric meters.

[0042] However, when the switching power supply chip is turned off, the transformer itself has leakage inductance, and the primary current and the secondary current form a crossover area, causing a spike voltage on the primary side. At the same time, there is also leakage inductance on the secondary side, which combines with the output rectifier diode to cause a reverse recovery current spike, which is reflected to the primary winding and also causes a primary spike voltage. Based on the above transformer adopting the forward winding method, the method of first winding the magnetic core shielding winding, primary winding, shielding winding, main winding, auxiliary winding, and VCC winding can effectively reduce the damped oscillation wave signal generated by the primary spike voltage.

[0043] See also Figure 3 , which is a circuit diagram of a three-phase voltage positive pole of a metering chip provided in Example 2 of the present application. The electric meter circuit also includes a first ADC voltage sampling circuit, a second ADC sampling circuit and a third ADC sampling circuit. Each ADC sampling circuit is grounded after passing through a first voltage-dividing resistor and a second voltage-dividing resistor. A filter capacitor is connected in parallel to the second voltage-dividing resistor. A first magnetic bead is arranged between the first voltage-dividing resistor and the second voltage-dividing resistor. An output end of the corresponding ADC sampling circuit is led out between the first magnetic bead and the second voltage-dividing resistor.

[0044] The input end of the first ADC voltage sampling circuit is used to connect the A-phase live wire of the electric meter, the output end of the first ADC voltage sampling circuit is used to connect the A-phase ADC voltage sampling terminal of the metering chip in the metering circuit, the input end of the second ADC voltage sampling circuit is used to connect the B-phase live wire of the electric meter, the output end of the second ADC voltage sampling circuit is used to connect the B-phase ADC voltage sampling terminal of the metering chip, the input end of the third ADC voltage sampling circuit is used to connect the C-phase live wire of the electric meter, and the output end of the third ADC voltage sampling circuit is used to connect the C-phase ADC voltage sampling terminal of the metering chip.

[0045] In one implementation, an RC circuit is connected in parallel to the second voltage-dividing resistor, and an output terminal of the corresponding ADC sampling circuit is connected between the resistor and the capacitor of the RC circuit.

[0046] In one implementation, the first voltage-dividing resistor includes six 330KΩ resistors connected in series, and the second voltage-dividing resistor includes a 1KΩ resistor.

[0047] Among them, UA, UB, UC, and UN are three live wires and a neutral wire, respectively, realizing three-way voltage ADC and four-way current ADC. The A-phase voltage sampling uses six 330K resistors (i.e., R14 to R19) and a 1K resistor (i.e., R20) to divide the voltage and enter the A-phase ADC of the metering chip. A bit-numbered magnetic bead L210 is added between R19 and R20. The purpose of the magnetic bead L210 is to suppress high-frequency noise and spike interference on the signal line and power line. In addition, in order to prevent the magnetic bead from absorbing insufficiently and still having high-frequency noise and spike interference at the back end, a chip resistor (i.e., R48) and a chip capacitor (i.e., C40) are added at the back end of the magnetic bead to form an RC circuit to further filter out high-frequency noise and spike interference, ensuring that the voltage entering the A-phase ADC of the metering chip is stable and reliable.

[0048] The B-phase voltage is divided by six 330K resistors (R34 to R39) and a 1K resistor (R40) and enters the B-phase ADC of the metering chip. A magnetic bead (L211) is added between R39 and R40, and a chip resistor (R49) and a chip capacitor (C39) are added to the rear end of the magnetic bead to form an RC circuit to suppress high-frequency noise and spike interference, ensuring that the B-phase ADC voltage entering the metering chip is stable and reliable.

[0049] The C-phase voltage is divided by six 330K resistors (R54 to R59) and a 1K resistor (R60) and enters the C-phase ADC of the metering chip. A magnetic bead (L212) is added between R59 and R60, and a chip resistor (R68) and a chip capacitor (C38) are added to the rear end of the magnetic bead to form an RC circuit to suppress high-frequency noise and spike interference, ensuring that the C-phase ADC voltage entering the metering chip is stable and reliable.

[0050] By adding magnetic beads and RC circuits to the back end of each voltage sampling signal, the damped oscillation wave signal is attenuated and absorbed to prevent the ADC port of the metering chip from sampling abnormal voltage and causing error jumps.

[0051] like Figure 4 , which is a circuit diagram of a three-phase voltage negative pole of a metering chip provided in Embodiment 2 of the present application, wherein VAN, VBN and VCN correspond to the VAN terminal, VBN terminal and VCN terminal of the metering chip respectively.

[0052] like Figure 4 As shown, it is a circuit diagram of the positive and negative poles of the three-phase current of a metering chip provided in Example 2 of the present application, wherein IAP / IAN, IBP / IBN, ICP / ICN and INP / INN respectively represent the positive and negative poles of the A-phase line current, the positive and negative poles of the B-phase line current, the positive and negative poles of the C-phase line current and the positive and negative poles of the neutral line current, and correspond to the IAP terminal / IAN terminal, IBP terminal / IBN terminal, ICP terminal / ICN terminal and INP terminal / INN terminal connected to the metering chip respectively.

[0053] like Figure 6 As shown, it is a connection diagram of a metering chip control circuit provided in the second embodiment of the present application, wherein the metering chip (i.e., U10) used in this embodiment adopts the RN8302B chip. Specifically, the metering chip includes 7 high-precision ADCs, which correspond to the above-mentioned three voltage ADCs and four current ADCs respectively.

[0054] See also Figure 7 , is a schematic diagram of the connection between the neutral line and the ground provided in Example 3 of the present application, wherein the electric meter circuit also includes a neutral line grounding circuit, a second magnetic bead is arranged on the neutral line grounding circuit, one end of the second magnetic bead is used to connect the neutral line, and the other end of the second magnetic bead is grounded.

[0055] A magnetic bead (i.e. L208) is connected in series between the metering ground wire and the neutral wire to suppress the error jump caused by ground wire jitter. This magnetic bead needs to have strong current resistance to prevent damage caused by excessive lightning surges. It can effectively prevent the metering chip ground wire from being interfered by the damped oscillation wave signal.

[0056] See also Figure 8 , is a connection diagram of a metering chip power supply circuit provided in Example 4 of the present application, wherein the electric meter circuit also includes a metering chip power supply circuit, a third magnetic bead is arranged on the metering chip power supply circuit, one end of the third magnetic bead is connected to a voltage source, and the other end of the third magnetic bead is used to connect to the VCC terminal of the metering chip in the metering circuit.

[0057] In addition, a first transistor is provided on the power supply circuit of the metering chip, the control end of the first transistor is used to connect the control signal, the input end of the first transistor is connected to the third magnetic bead, and the output end of the first transistor is used to connect the VCC terminal of the metering chip in the metering circuit.

[0058] A magnetic bead (i.e., L209) is used before the VCC power supply enters the metering chip to ensure that the VCC power supply entering the metering chip is clean, effectively preventing the voltage converted from the transformer from entering the VCC power supply of the metering chip from being affected by the damped oscillation wave.

[0059] After the above circuit, the damped oscillation wave test was carried out using the State Grid D-level three-phase four-wire transformer access meter. During the entire test process, whether it was differential mode or common mode, the error was very stably controlled below 0.1, which fully complies with the grid error standard requirement of less than 1.0.

[0060] Furthermore, the present application can also use a higher-level metering chip, the dynamic range of the metering chip reaches 20000:1, including power quality analysis, providing higher frequency fixed sampling or synchronous sampling data, supporting the storage of some abnormal waveforms, using an oscilloscope to capture the damped oscillation wave waveforms in differential mode and common mode, analyzing these waveform frequencies, amplitudes, rising edges, and falling edges, and using these waveform data to establish a space to store damped oscillation wave waveforms in the metering chip. Once a similar damped oscillation wave appears in an experiment or on site, the metering chip can immediately identify and filter out these interference signals, extract useful fundamental wave data to ensure that the power is real and reliable.

[0061] In addition, no hardware modification is made on the basis of the existing metering chip, and the damped oscillation wave signal is identified by software. However, due to the limited sampling rate and bandwidth of the metering chip, it cannot guarantee that every interference signal can be identified. The metering chip identifies these damped oscillation wave signals, and the software uses the average slip method to control the error within the grid standard range.

[0062] The present application adopts a new transformer winding method to reduce the interference of the metering chip power supply caused by noise or radiation, thereby causing error jumps, and the three-way voltage sampling uses a combination of magnetic beads and RC circuits to absorb and filter out damped oscillation wave signals, ensuring error stability and ensuring that the power is real and reliable, thus solving user disputes caused by unstable and unreliable power.

[0063] In addition, an embodiment of the present application further provides a smart meter, which includes a metering chip and a meter circuit connected to the metering chip. The meter circuit adopts the above-mentioned circuit, and the details are not repeated here.

[0064] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An electric meter circuit for suppressing damped oscillation waves, characterized in that: The electric meter circuit includes a switching power supply and a transformer. The transformer is wound in a forward direction to form a magnetic core shielding winding, a primary winding, a shielding winding, a main winding, an auxiliary winding and a VCC winding in sequence. The magnetic core shielding winding and the primary winding are wound in opposite directions and the starting point is connected to the static point of the switching power supply. The ratio of the number of turns of the magnetic core shielding winding to the number of turns of the primary winding is a preset value, and the preset value is less than 1. The magnetic core shielding winding, the primary winding, the shielding winding and the VCC winding are all arranged on the primary side of the transformer, the main winding and the auxiliary winding are all arranged on the secondary side of the transformer, the main winding is used to connect the 485 circuit, carrier circuit, and relay circuit of the electric meter for power supply, and the auxiliary winding is used to connect the MCU circuit, metering circuit and MCU peripheral circuit in the electric meter for power supply.

2. The electric meter circuit according to claim 1, characterized in that: Each layer of the primary winding, the main circuit winding, the auxiliary circuit winding and the VCC winding is tightly wound in one layer.

3. The electric meter circuit according to claim 1, characterized in that: The three-way voltage sampling circuit of the electric meter also includes a first ADC voltage sampling circuit, a second ADC sampling circuit and a third ADC sampling circuit, each ADC sampling circuit is grounded after passing through a first voltage-dividing resistor and a second voltage-dividing resistor, a filter capacitor is connected in parallel to the second voltage-dividing resistor, a first magnetic bead is arranged between the first voltage-dividing resistor and the second voltage-dividing resistor, and an input end of the corresponding ADC sampling circuit is led out between the first magnetic bead and the second voltage-dividing resistor; The input end of the first ADC voltage sampling circuit is used to connect the A-phase live wire of the electric meter, the output end of the first ADC voltage sampling circuit is used to connect the A-phase ADC voltage sampling terminal of the metering chip in the metering circuit, the input end of the second ADC voltage sampling circuit is used to connect the B-phase live wire of the electric meter, the output end of the second ADC voltage sampling circuit is used to connect the B-phase ADC voltage sampling terminal of the metering chip, the input end of the third ADC voltage sampling circuit is used to connect the C-phase live wire of the electric meter, and the output end of the third ADC voltage sampling circuit is used to connect the C-phase ADC voltage sampling terminal of the metering chip.

4. The electric meter circuit according to claim 3, characterized in that: An RC circuit is also connected in parallel to the second voltage-dividing resistor, and an output end of the corresponding ADC sampling circuit is led out between the resistor and the capacitor of the RC circuit.

5. The electric meter circuit according to claim 1, characterized in that: The first voltage-dividing resistor includes six 330KΩ resistors connected in series, and the second voltage-dividing resistor includes a 1KΩ resistor.

6. The electric meter circuit according to claim 1, characterized in that: The electric meter circuit also includes a neutral line grounding circuit, on which a second magnetic bead is arranged, one end of the second magnetic bead is used to connect the neutral line, and the other end of the second magnetic bead is grounded.

7. The electric meter circuit according to claim 1, characterized in that: The electric meter circuit also includes a metering chip power supply circuit, on which a third magnetic bead is arranged, one end of the third magnetic bead is connected to a voltage source, and the other end of the third magnetic bead is used to connect to the VCC terminal of the metering chip in the metering circuit.

8. The electric meter circuit according to claim 1, characterized in that: A first transistor is also provided on the metering chip power supply circuit, the control end of the first transistor is used to connect the control signal, the input end of the first transistor is connected to the third magnetic bead, and the output end of the first transistor is used to connect the VCC terminal of the metering chip in the metering circuit.

9. The electric meter circuit according to claim 1, characterized in that: The preset value is 2 / 3.

10. A smart electric meter, characterized in that: The smart electric meter comprises a metering chip in a metering circuit and an electric meter circuit connected to the metering chip, and the electric meter circuit is the electric meter circuit according to any one of claims 1 to 9.

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