Electric energy meter compatible with three-phase three-wire and three-phase four-wire wiring

Abstract

The utility model discloses an electric energy meter compatible with three-phase three-wire and three-phase four-wire wiring, which comprises a power supply compatible circuit, the power supply compatible circuit comprises a primary side power supply circuit, a high-frequency transformer, a communication power supply circuit and a metering power supply circuit, the input end of the primary side power supply circuit is connected with a power grid, and the output end of the primary side power supply circuit is connected with the input end of the high-frequency transformer; the first output end of the high-frequency transformer is connected with the input end of the communication power supply circuit, the second output end of the high-frequency transformer is connected with the input end of the metering power supply circuit, the output end of the communication power supply circuit is used for supplying power to the communication module, and the output end of the metering power supply circuit is used for supplying power to the metering module. During three-phase three-wire wiring, the N-phase terminal of the primary side circuit is not connected with a power grid; and during three-phase four-wire wiring, the N-phase terminal of the primary side circuit is connected with the N-phase wire of the power grid. The electric energy meter can be compatible with different wires, and the reliability of the electric energy meter is improved.

Description

Technical Field

[0001] This utility model relates to the field of electricity meters, and in particular to an electricity meter compatible with three-phase three-wire and three-phase four-wire wiring. Background Technology

[0002] Traditional three-phase electricity meters include two types: three-phase three-wire electricity meters and three-phase four-wire electricity meters. If a three-phase three-wire electricity meter is mistakenly used in a three-phase four-wire system or vice versa during installation, it will lead to inaccurate metering and may even damage the electricity meter or affect the safe and stable operation of the entire power system.

[0003] With the continuous development of power systems, higher demands are placed on the flexibility and compatibility of electricity metering equipment. Especially in some power renovation projects or multi-scenario applications, there is a need for an electricity meter that can be compatible with both three-phase three-wire and three-phase four-wire wiring to reduce installation errors, improve the accuracy and reliability of electricity metering, and reduce overall costs. Summary of the Invention

[0004] This utility model provides an energy meter that is compatible with both three-phase three-wire and three-phase four-wire wiring, in order to solve the problems of incompatibility between three-phase three-wire and three-phase four-wire wiring and power supply incompatibility between traditional three-phase energy meters.

[0005] To achieve the above objectives, in one embodiment, an energy meter compatible with both three-phase three-wire and three-phase four-wire wiring is provided, comprising: a power compatibility circuit, the power compatibility circuit including: a primary power supply circuit, a high-frequency transformer, a communication power supply circuit, and a metering power supply circuit, wherein the input terminal of the primary power supply circuit is connected to the power grid, the output terminal of the primary power supply circuit is connected to the input terminal of the high-frequency transformer, the first output terminal of the high-frequency transformer is connected to the input terminal of the communication power supply circuit, the second output terminal of the high-frequency transformer is connected to the input terminal of the metering power supply circuit, the output terminal of the communication power supply circuit is used to power a communication module, and the output terminal of the metering power supply circuit is used to power a metering module;

[0006] The A-phase terminal of the primary power supply circuit is connected to the A-phase wire of the power grid, the B-phase terminal of the primary power supply circuit is connected to the B-phase wire of the power grid, and the C-phase terminal of the primary power supply circuit is connected to the C-phase wire of the power grid. In a three-phase three-wire connection, the N-phase terminal of the primary power supply circuit is not connected to the power grid; in a three-phase four-wire connection, the N-phase terminal of the primary power supply circuit is connected to the N-phase wire of the power grid.

[0007] In one embodiment, the primary-side power supply circuit includes: a first switching switch and a second switching switch, one end of the first switching switch being connected to the B-phase terminal and the other end of the first switching switch being connected to the C-phase terminal, one end of the second switching switch being connected to the B-phase terminal and the other end of the second switching switch being connected to the N-phase terminal, wherein the first switching switch is used to close when switching from three-phase four-wire to three-phase three-wire, and the second switching switch is also used to close when switching from three-phase four-wire to three-phase three-wire.

[0008] In one embodiment, the primary-side power supply circuit further includes: an AC signal conditioning circuit, a rectifier circuit, a protection circuit, a DC signal conditioning circuit, and a switching power supply integrated module, wherein the input terminal of the AC signal conditioning circuit is connected to the power grid, the output terminal of the AC signal conditioning circuit is connected to the input terminal of the rectifier circuit, the output terminal of the rectifier circuit is connected to the input terminal of the protection circuit, the output terminal of the protection circuit is connected to the input terminal of the DC signal conditioning circuit, and the output terminal of the DC signal conditioning circuit is connected to the input terminal of the high-frequency transformer;

[0009] The DC signal conditioning circuit includes a voltage divider. The input of the voltage divider is connected to the input of the high-frequency transformer, and the output of the voltage divider is connected to the control terminal of the switching power supply integrated module.

[0010] In one embodiment, the voltage divider is a switching transistor, and the DC signal conditioning circuit further includes: a voltage divider branch, a first voltage regulator branch, a second voltage regulator branch, and a primary-side absorption branch. One end of the voltage divider branch is connected to a first power supply terminal, and the other end of the voltage divider branch is connected to the input terminal of the first voltage regulator branch, the output terminal of the second voltage regulator branch, and the controlled terminal of the switching transistor. The output terminal of the first voltage regulator branch is grounded, the input terminal of the second voltage regulator branch is connected to the output terminal of the switching transistor and the control terminal of the switching power supply integrated module, the input terminal of the primary-side absorption branch is connected to the first power supply terminal, and the output terminal of the primary-side absorption branch is connected to the input terminal of the high-frequency transformer.

[0011] In one embodiment, a feedback circuit is further included, comprising: an optocoupler module, a first voltage regulation feedback module, and a second voltage regulation feedback module. The input terminal of the first voltage regulation feedback module is connected to the first output terminal of the high-frequency transformer, the output terminal of the first voltage regulation feedback module is connected to the input terminal of the optocoupler module, the output terminal of the optocoupler module is connected to the input terminal of the second voltage regulation feedback module, and the input terminal of the second voltage regulation feedback module is connected to the power supply terminal of the switching power supply integrated module.

[0012] In one embodiment, the AC signal conditioning circuit includes a varistor module and a filter module. The input terminal of the varistor module is connected to the power grid, the output terminal of the varistor module is connected to the input terminal of the filter module, and the output terminal of the filter module is connected to the input terminal of the rectifier circuit.

[0013] In one embodiment, the protection circuit includes: a noise signal filtering branch, a balanced voltage divider branch, and a first filtering branch, wherein the input terminal of the noise signal filtering branch is connected to the output terminal of the rectifier circuit, the output terminal of the noise signal filtering branch is connected to the input terminal of the balanced voltage divider branch, the output terminal of the balanced voltage divider branch is connected to the input terminal of the first filtering branch, and the output terminal of the first filtering branch is connected to the input terminal of the DC signal conditioning circuit.

[0014] In one embodiment, a power supply module circuit is further included. The power supply module circuit includes a first absorption resistor, a first capacitor, a first rectifier diode, and a first filter capacitor. One end of the first filter capacitor is connected to a second power supply terminal, and the other end of the first filter capacitor is grounded. One end of the first absorption resistor is connected to the second power supply terminal. The first capacitor is connected in series with the first absorption resistor. The other end of the first capacitor is connected to the input terminal of the power supply module circuit. The anode of the first rectifier diode is connected to one end of the first absorption resistor, and the cathode of the first rectifier diode is connected to the other end of the first capacitor. The output terminal of the power supply module circuit is connected to the ground terminal.

[0015] In one embodiment, the metering power supply circuit includes: a second absorption resistor, a second capacitor, a second rectifier diode, and a second filter branch. The second output terminal of the high-frequency transformer is connected to one end of the second absorption resistor and the cathode of the second rectifier diode. The second capacitor is connected in series with the second absorption resistor. The other end of the second absorption resistor is connected to the anode of the second rectifier diode. The anode of the second rectifier diode is also connected to the input terminal of the second filter branch. The input terminal of the second filter branch is also connected to a third power supply terminal. The output terminal of the second filter branch is grounded.

[0016] In one embodiment, the communication power supply circuit includes: a rectifier absorption branch, a harmonic filter branch, and a buffer branch, wherein the input terminal of the rectifier absorption branch is connected to the first output terminal of the high-frequency transformer, the output terminal of the rectifier absorption branch is connected to the input terminal of the harmonic filter branch, the output terminal of the harmonic filter branch is connected to the input terminal of the buffer branch, and the output terminal of the buffer branch is used to supply power to the communication module of the energy meter.

[0017] The aforementioned energy meter, compatible with both three-phase three-wire and three-phase four-wire wiring, connects the input terminal of the primary power supply circuit to the power grid. In three-phase three-wire wiring, the N-phase terminal of the primary power supply circuit is not connected to the power grid; in three-phase four-wire wiring, the N-phase terminal of the primary power supply circuit is connected to the N-phase power grid line. This allows the same three-phase energy meter to be compatible with both three-phase three-wire and three-phase four-wire wiring. The power grid signal input to the primary power supply circuit is integrated through the primary power supply circuit, accommodating different voltage inputs under both wiring configurations. This improves the applicability of the energy meter in different power supply systems, reduces the types of energy metering equipment in the power system, simplifies installation and maintenance processes, and reduces costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram showing the connection of various parts of the power compatibility circuit of an energy meter in one embodiment of this utility model;

[0020] Figure 2 This is a schematic diagram of a three-phase four-wire wiring in one embodiment of this utility model;

[0021] Figure 3 This is a schematic diagram of a three-phase three-wire wiring in one embodiment of this utility model;

[0022] Figure 4 This is a schematic diagram of another three-phase three-wire connection in one embodiment of this utility model;

[0023] Figure 5 This is a partial schematic diagram of the primary-side circuit in one embodiment of the present invention;

[0024] Figure 6 This is a schematic diagram of another part of the primary circuit, the high-frequency transformer, the communication power supply circuit, and the metering power supply circuit in one embodiment of this utility model.

[0025] Reference numerals in the attached diagram: 1. Primary power supply circuit; 101. AC signal conditioning circuit; 1011. Varistor module; 1012. Filter module; 102. Rectifier circuit; 103. Protection circuit; 1031. First balanced voltage divider branch; 1032. Second balanced voltage divider branch; 104. DC signal conditioning circuit; 1041. Voltage divider branch; 1042. First voltage regulator branch; 1043. Second voltage regulator branch; 1044. Primary absorption branch; 2. High-frequency transformer; 3. Communication power supply circuit; 301. Rectifier absorption branch; 302. Harmonic filter branch; 303. Buffer branch; 4. Metering power supply circuit; 401. Second filter branch; 5. Feedback circuit; 501. Optocoupler module; 502. First voltage regulator feedback module; 503. Second voltage regulator feedback module; 6. Power supply module power supply circuit. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0027] It should be understood that this invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this invention to those skilled in the art. In the drawings, for clarity, the dimensions of layers and regions, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0028] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this utility model, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0029] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0031] To fully understand this utility model, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this utility model. Preferred embodiments of this utility model are described in detail below; however, in addition to these detailed descriptions, this utility model may have other embodiments.

[0032] In one embodiment, an energy meter compatible with both three-phase three-wire and three-phase four-wire wiring is provided, comprising: a power compatibility circuit, such as... Figure 1 As shown, the power compatibility circuit includes: a primary-side power supply circuit 1, a high-frequency transformer 2, a communication power supply circuit 3, and a metering power supply circuit 4. The input terminal of the primary-side power supply circuit 1 is connected to the power grid, the output terminal of the primary-side power supply circuit 1 is connected to the input terminal of the high-frequency transformer 2, the first output terminal of the high-frequency transformer 2 is connected to the input terminal of the communication power supply circuit 3, the second output terminal of the high-frequency transformer 2 is connected to the input terminal of the metering power supply circuit 4, the output terminal of the communication power supply circuit 3 is used to power the communication module, and the output terminal of the metering power supply circuit 4 is used to power the metering module.

[0033] like Figure 2 and 3As shown, the A-phase terminal of the primary power supply circuit 1 is connected to the A-phase wire L1 of the power grid, the B-phase terminal of the primary power supply circuit 1 is connected to the B-phase wire L2 of the power grid, and the C-phase terminal of the primary power supply circuit 1 is connected to the C-phase wire L3 of the power grid. In a three-phase three-wire connection, the N-phase terminal of the primary power supply circuit 1 is not connected to the power grid; in a three-phase four-wire connection, the N-phase terminal of the primary power supply circuit 1 is connected to the N-phase wire of the power grid.

[0034] Among them, the terminals of the primary power supply circuit 1 are voltage terminals, and the output terminal of the communication power supply circuit 3 outputs a voltage of about 12V to power the external communication module.

[0035] The working process of the above-mentioned electricity meter is as follows:

[0036] When a three-phase three-wire connection is made, the A, B, and C phase terminals of the primary power supply circuit receive voltage signals from the A, B, and C phase wires of the power grid, respectively.

[0037] In a three-phase four-wire connection, the A, B, C, and N phase terminals of the primary power supply circuit receive voltage signals from the A, B, C, and N phase wires of the power grid, respectively.

[0038] The received voltage signal is processed by the primary power supply circuit and transmitted to the high-frequency transformer. After energy conversion by the high-frequency transformer, it is output to the communication power supply circuit through the first output terminal to power the external communication module, and then output to the metering power supply circuit through the second output terminal to power the metering module.

[0039] In this embodiment, the input terminal of the primary power supply circuit is connected to the power grid wire. In the case of three-phase three-wire connection, the N-phase terminal of the primary power supply circuit is not connected to the power grid. In the case of three-phase four-wire connection, the N-phase terminal of the primary power supply circuit is connected to the N-phase power grid wire. This enables the same energy meter to be compatible with both three-phase three-wire and three-phase four-wire connections. The power grid signal input to the primary power supply circuit is integrated through the primary power supply circuit, which is compatible with different voltage inputs under both three-phase three-wire and three-phase four-wire connections. This improves the applicability of the energy meter in different power supply systems, reduces the types of energy metering equipment in the power system, simplifies the installation and maintenance process, and reduces costs.

[0040] In one embodiment, such as Figure 5As shown, the primary power supply circuit 1 includes: a first switching switch RT1 and a second switching switch RT5. One end of the first switching switch RT1 is connected to the B-phase terminal, and the other end of the first switching switch RT1 is connected to the C-phase terminal. One end of the second switching switch RT5 is connected to the B-phase terminal, and the other end of the second switching switch RT5 is connected to the N-phase terminal. The first switching switch RT5 is used to close when switching from three-phase four-wire to three-phase three-wire, and the second switching switch RT5 is also used to close when switching from three-phase four-wire to three-phase three-wire.

[0041] When the first and second switching switches are open, the three-phase three-wire connection is the type of three-phase three-wire connection mentioned in the previous embodiment, such as... Figure 3 As shown, the N-phase terminal of the primary power supply circuit is not connected to the power grid; when the first and second switching switches are closed, it is another three-phase three-wire connection mentioned in this embodiment, such as... Figure 4 As shown.

[0042] In this embodiment, by opening and closing the first switching switch, the energy meter can be compatible with three types of wiring, including three-phase four-wire wiring and two types of three-phase three-wire wiring, to adapt to different power systems. This avoids inaccurate metering or damage to the energy meter caused by wiring errors. The wiring switching can be completed using only one energy meter without replacement, saving costs.

[0043] In one embodiment, such as Figure 5 and Figure 6 As shown, the primary-side power supply circuit 1 further includes: an AC signal conditioning circuit 101, a rectifier circuit 102, a protection circuit 103, a DC signal conditioning circuit 104, and a switching power supply integrated module U11. The input terminal of the AC signal conditioning circuit 101 is connected to the power grid, the output terminal of the AC signal conditioning circuit 101 is connected to the input terminal of the rectifier circuit 102, the output terminal of the rectifier circuit 102 is connected to the input terminal of the protection circuit 103, the output terminal of the protection circuit 103 is connected to the input terminal of the DC signal conditioning circuit 104, and the output terminal of the DC signal conditioning circuit 104 is connected to the input terminal of the high-frequency transformer 2.

[0044] The DC signal conditioning circuit 102 is equipped with a voltage divider M1. The input terminal of the voltage divider M1 is connected to the input terminal of the high-frequency transformer 2, and the output terminal of the voltage divider M1 is connected to the control terminal SW of the switching power supply integrated module U11.

[0045] Among them, the switching power supply integrated module U11 adopts the 8234T series, which realizes efficient conversion of electrical energy through high-frequency switching action. The rectifier circuit 102 includes 16 rectifier diodes from D19 to D34.

[0046] The operation of the primary-side power supply circuit described above is as follows:

[0047] The input terminal of the AC signal conditioning circuit receives the grid voltage signal. After processing by the AC signal conditioning circuit, it is output to the rectifier circuit. The rectifier circuit rectifies the three-phase AC voltage into DC pulsating voltage, and then outputs it to the protection circuit. After processing by the protection circuit, it outputs it to the DC signal conditioning circuit. After further conditioning by the DC signal conditioning circuit, it outputs it to the high-frequency transformer.

[0048] In this embodiment, the AC signal conditioning circuit handles surge voltage and current impacts from the power grid, as well as conducted and radiated interference voltages generated by the switching power supply integrated module. It also prevents external electromagnetic interference from affecting the normal operation of the circuit. This not only protects the power compatibility circuit in the energy meter from voltage and current impacts and improves the service life of the energy meter, but also makes the signal output by the power compatibility circuit in the energy meter more reliable.

[0049] In one embodiment, such as Figure 6 As shown, the voltage divider M1 is a MOS switch. The DC signal conditioning circuit 104 further includes a voltage divider branch 1041, a first voltage regulator branch 1042, a second voltage regulator branch 1043, and a primary-side absorption branch 1044. One end of the voltage divider branch 1041 is connected to the first power supply terminal HVIN. The other end of the voltage divider branch 1041 is connected to the input terminal of the first voltage regulator branch 1042, the output terminal of the second voltage regulator branch 1043, and the controlled terminal of the MOS switch M1. The output terminal of the first voltage regulator branch 1042 is grounded to GND1. The input terminal of the second voltage regulator branch 1043 is connected to the output terminal of the MOS switch M1 and the control terminal SW of the switching power supply integrated module U11. The input terminal of the primary-side absorption branch 1044 is connected to the first power supply terminal HVIN. The output terminal of the primary-side absorption branch 1044 is connected to the input terminal of the high-frequency transformer 2.

[0050] Among them, the MOS switch M1 remains on when the circuit is working, is connected to the control terminal SW of the switching power supply integrated module U11, and is connected in series with the MOS transistor inside the switching power supply integrated module U11 to share the surge voltage and VDS voltage; the primary side absorption branch 1044 improves the voltage and current of the power compatibility circuit in the energy meter during turn-on and turn-off, reducing fluctuations and impacts.

[0051] The operation of the DC signal conditioning circuit described above is as follows:

[0052] The voltage divider branch and the primary-side absorption branch process the output signal of the protection circuit. After voltage division and filtering, the signal is output to the high-frequency transformer, then to the switching transistor, and finally to the switching power supply integrated module after voltage division by the switching transistor.

[0053] In this embodiment, the switching transistor is connected in series with the MOSFET inside the switching power supply integrated module, which improves the withstand voltage of the MOSFET inside the switching power supply integrated module, thereby increasing the withstand voltage range of the power supply compatibility circuit in the entire energy meter and enabling wide voltage input under different wiring methods of three-phase three-wire and three-phase four-wire.

[0054] In one embodiment, such as Figure 6 As shown, it also includes a feedback circuit 5, which includes an optocoupler module 501, a first voltage regulation feedback module 502, and a second voltage regulation feedback module 503. The input terminal of the first voltage regulation feedback module 502 is connected to the first output terminal of the high-frequency transformer 2, the output terminal of the first voltage regulation feedback module 502 is connected to the input terminal of the optocoupler module 501, the output terminal of the optocoupler module 501 is connected to the input terminal of the second voltage regulation feedback module 503, and the input terminal of the second voltage regulation feedback module 503 is connected to the power supply terminal of the switching power supply integrated module U11.

[0055] The feedback circuit 5 monitors the voltage of the power compatibility circuit in the energy meter in real time. When the voltage deviates from the set value, it adjusts the circuit to quickly restore the set voltage value, so that the energy meter can maintain normal operation even when the external environment changes.

[0056] In this embodiment, the voltage regulation feedback circuit enables the circuit to quickly restore the set voltage value, improving the efficiency of the power compatibility circuit in the energy meter. By setting the voltage regulation feedback circuit to monitor the voltage in real time, circuit failures caused by abnormal voltage are avoided, thus improving the reliability of the energy meter.

[0057] In one embodiment, such as Figure 5 As shown, the AC signal conditioning circuit 101 includes a varistor module 1011 and a filter module 1012. The input terminal of the varistor module 1011 is connected to the power grid, the output terminal of the varistor module 1011 is connected to the input terminal of the filter module 1012, and the output terminal of the filter module 1012 is connected to the input terminal of the rectifier circuit 102.

[0058] The varistor module 1011 contains three varistors, V1, V2, and V3. The voltage terminals of the power grid pass through the three varistors in the varistor module 1011 to suppress and discharge the surge voltage and current impact of the power grid, and then output to the filter module 1012. The filter module 1012 includes three filter inductors, L3, L4, and L5, and three filter capacitors, C147, C129, and C130, to filter out the conducted and radiated interference voltage generated inside the switching power supply integrated module U11 in the power compatibility circuit of the energy meter and external electromagnetic interference.

[0059] In this embodiment, a varistor module and a filter module are set in the AC signal conditioning circuit to process the voltage signal of the power grid, thereby protecting the power compatibility circuit in the energy meter and ensuring the safe operation and accurate measurement of the energy meter.

[0060] In one embodiment, the protection circuit 103 includes: a noise signal filtering branch, a balanced voltage divider branch, and a first filtering branch, wherein the input terminal of the noise signal filtering branch is connected to the output terminal of the rectifier circuit, the output terminal of the noise signal filtering branch is connected to the input terminal of the balanced voltage divider branch, the output terminal of the balanced voltage divider branch is connected to the input terminal of the first filtering branch, and the output terminal of the first filtering branch is connected to the input terminal of the DC signal conditioning circuit.

[0061] Among them, such as Figure 5 As shown, the noise signal filtering branch includes: capacitor C137, common-mode inductor L8, and differential-mode inductor L2. The balanced voltage divider branch includes: a first balanced voltage divider branch 1031 and a second balanced voltage divider branch 1032. The first filtering branch includes: a second filtering capacitor C119 and a third filtering capacitor C121. One end of capacitor C137 is connected to the output terminal of rectifier circuit 102 and the first input terminal of common-mode inductor L8. The other end of capacitor C137 is connected to the output terminal of rectifier circuit 102 and the second input terminal of common-mode inductor L8. The first output terminal of common-mode inductor L8... One end of the differential-mode inductor L2 is connected, and the second output terminal of the common-mode inductor L8 is connected to one end of the second balanced voltage divider branch 1032 and ground GND1. The other end of the differential-mode inductor L2 is connected to one end of the first balanced voltage divider branch 1031, one end of the second filter capacitor C119, and the first power supply terminal HVIN. The other end of the first balanced voltage divider branch 1031 is connected to the other end of the second balanced voltage divider branch 1032, the other end of the second filter capacitor C119, and one end of the third filter capacitor C121. The other end of the third filter capacitor C121 is grounded to GND1.

[0062] The input terminal of the protection circuit 103 receives the DC pulsating voltage processed by the rectifier circuit 102. After passing through capacitor C137, common-mode inductor L8, and differential-mode inductor L2, it reaches the second filter capacitor C119 and the third filter capacitor C121 for filtering. Then, it outputs high-voltage DC power to the DC signal conditioning circuit 104 to provide high-voltage DC power to the switching power supply integrated module U11. The first balanced voltage divider branch 1031 includes three resistors R24, R25, and R31, and the second balanced voltage divider branch 1032 includes three resistors R164, R166, and R167. The first balanced voltage divider branch 1031 and the second balanced voltage divider branch 1032 are the balancing resistors of the second filter capacitor C119 and the third filter capacitor C121, used to balance the voltage and avoid abnormal operation caused by uneven voltage values ​​between the two filter capacitors.

[0063] In this embodiment, the common-mode inductor suppresses common-mode noise and interference in the circuit, improving circuit stability and reducing interference to other components in the circuit; the differential-mode inductor suppresses differential-mode interference, improving the circuit's anti-interference capability and ensuring signal stability; and the filter capacitor balances high-frequency noise and ripple, making the output DC more stable and improving signal quality.

[0064] In one embodiment, such as Figure 6 As shown, it also includes a power supply module circuit 6, which includes: a first absorption resistor R249, a first capacitor C9, a first rectifier diode D10, and a first filter capacitor C10. One end of the first filter capacitor C10 is connected to the second power supply terminal 15V1, and the other end of the first filter capacitor C10 is grounded to GND1. One end of the first absorption resistor R249 is connected to the second power supply terminal 15V1. The first capacitor C9 is connected in series with the first absorption resistor R249, and the other end of the first capacitor C9 is connected to the input terminal of the power supply module circuit 6. The anode of the first rectifier diode D10 is connected to one end of the first absorption resistor R249, and the cathode of the first rectifier diode D10 is connected to the other end of the first capacitor C9. The output terminal of the power supply module circuit 6 is connected to the ground terminal GND1.

[0065] Among them, the power supply module power supply circuit 6 is used to provide working voltage to the switching power supply integrated module U11. The first filter capacitor C10 is used for filtering. The first absorption resistor R249 and the first capacitor C9 form an RC absorption circuit to absorb the instantaneous overvoltage generated during the conduction and turn-off process. When the circuit is on, it limits the rate of rise of the current. The first rectifier diode D10 can prevent reverse current.

[0066] In this embodiment, the first absorption resistor and the first capacitor form an RC absorption circuit, which can reduce the turn-on loss of the circuit, balance voltage differences, achieve dynamic voltage equalization, reduce electromagnetic interference of the circuit, and improve the stability and reliability of the circuit; the first rectifier diode can protect other components in the circuit from damage.

[0067] In one embodiment, such as Figure 6As shown, the metering power supply circuit 4 includes: a second absorption resistor R172, a second capacitor C128, a second rectifier diode D33, and a second filter branch 401. The second output terminal of the high-frequency transformer 2 is connected to one end of the second absorption resistor R172 and the cathode of the second rectifier diode D33. The second capacitor C128 is connected in series with the second absorption resistor R172. The other end of the second absorption resistor R172 is connected to the anode of the second rectifier diode D33. The anode of the second rectifier diode D33 is also connected to the input terminal of the second filter branch 401. The input terminal of the second filter branch 401 is also connected to the third power supply terminal VHH1. The output terminal of the second filter branch 401 is grounded to GND.

[0068] The metering power supply circuit 4 is used to power the metering module. The second absorption resistor R172 and the second capacitor C128 form an RC absorption circuit to reduce the VDS spike pulse of the reverse voltage of the second rectifier diode D33. The second filter branch 401 includes four filter capacitors: C59, C52, C57 and C131, which process the signal and then power the metering module.

[0069] In this embodiment, a metering power supply circuit is set up to supply power to the metering module, and an RC absorption circuit, rectifier diodes and filter capacitors are set up to process the signal output to the metering module to achieve accurate metering of electricity.

[0070] In one embodiment, such as Figure 6 As shown, the communication power supply circuit 3 includes: a rectifier absorption branch 301, a harmonic filter branch 302, and a buffer branch 303. The input terminal of the rectifier absorption branch 301 is connected to the first output terminal of the high-frequency transformer 2, the output terminal of the rectifier absorption branch 301 is connected to the input terminal of the harmonic filter branch 302, the output terminal of the harmonic filter branch 302 is connected to the input terminal of the buffer branch 303, and the output terminal of the buffer branch 303 is used to supply power to the communication module of the energy meter.

[0071] Among them, such as Figure 6 As shown, the rectifier absorption branch is equipped with resistor R162, capacitor C118 and rectifier diode D31. Resistor R162 and capacitor C118 form an RC absorption circuit. The harmonic filter branch is equipped with four capacitors C124, C46, ​​C43 and C56, inductor L7 and resistor R9. The buffer branch is equipped with two resistors R14 and R208, which are dummy loads.

[0072] In this embodiment, a rectifier absorption branch is set in the power compatibility circuit of the energy meter to absorb voltage spike energy and prevent voltage from damaging other components in the power compatibility circuit of the energy meter. A harmonic filter branch is set to filter the signal and improve the circuit's anti-interference capability. A buffer branch is set to provide a dummy load. By setting different resistance values ​​of two resistors, different loads can be simulated to test and verify whether the signal output by the communication power supply circuit meets the power supply requirements of the communication module, thereby improving the accuracy of the power supply signal output to the communication module of the energy meter.

[0073] Preferably, the metering module of the electricity meter also includes a power correction unit and a function register, because in cases such as Figure 3 In the three-phase three-wire connection shown, the neutral wire of the meter is equivalent to a floating ground. Therefore, when the electricity meter is measuring, it is necessary to correct and compensate for the power deviation according to the measurement. At the same time, the mode of the function register is switched to three-phase three-wire to realize the accurate measurement of electricity meter by different wiring methods.

[0074] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. An energy meter compatible with both three-phase three-wire and three-phase four-wire wiring, characterized in that, include: A power compatibility circuit includes: a primary-side power supply circuit, a high-frequency transformer, a communication power supply circuit, and a metering power supply circuit. The input terminal of the primary-side power supply circuit is connected to the power grid, and the output terminal of the primary-side power supply circuit is connected to the input terminal of the high-frequency transformer. The first output terminal of the high-frequency transformer is connected to the input terminal of the communication power supply circuit, and the second output terminal of the high-frequency transformer is connected to the input terminal of the metering power supply circuit. The output terminal of the communication power supply circuit supplies power to the communication module of the energy meter, and the output terminal of the metering power supply circuit supplies power to the metering module of the energy meter. The A-phase terminal of the primary power supply circuit is connected to the A-phase wire of the power grid, the B-phase terminal of the primary power supply circuit is connected to the B-phase wire of the power grid, and the C-phase terminal of the primary power supply circuit is connected to the C-phase wire of the power grid. In a three-phase three-wire connection, the N-phase terminal of the primary power supply circuit is not connected to the power grid; in a three-phase four-wire connection, the N-phase terminal of the primary power supply circuit is connected to the N-phase wire of the power grid.

2. The electricity meter according to claim 1, characterized in that, The primary power supply circuit includes: a first switching switch and a second switching switch. One end of the first switching switch is connected to the B-phase terminal, and the other end of the first switching switch is connected to the C-phase terminal. One end of the second switching switch is connected to the B-phase terminal, and the other end of the second switching switch is connected to the N-phase terminal. The first switching switch is used to close when switching from three-phase four-wire to three-phase three-wire, and the second switching switch is also used to close when switching from three-phase four-wire to three-phase three-wire.

3. The electricity meter according to claim 2, characterized in that, The primary-side power supply circuit further includes: an AC signal conditioning circuit, a rectifier circuit, a protection circuit, a DC signal conditioning circuit, and a switching power supply integrated module. The input terminal of the AC signal conditioning circuit is connected to the power grid, the output terminal of the AC signal conditioning circuit is connected to the input terminal of the rectifier circuit, the output terminal of the rectifier circuit is connected to the input terminal of the protection circuit, the output terminal of the protection circuit is connected to the input terminal of the DC signal conditioning circuit, and the output terminal of the DC signal conditioning circuit is connected to the input terminal of the high-frequency transformer. The DC signal conditioning circuit includes a voltage divider. The input of the voltage divider is connected to the input of the high-frequency transformer, and the output of the voltage divider is connected to the control terminal of the switching power supply integrated module.

4. The electricity meter according to claim 3, characterized in that, The voltage divider is a switching transistor. The DC signal conditioning circuit further includes a voltage divider branch, a first voltage regulator branch, a second voltage regulator branch, and a primary-side absorption branch. One end of the voltage divider branch is connected to a first power supply terminal, and the other end of the voltage divider branch is connected to the input terminal of the first voltage regulator branch, the output terminal of the second voltage regulator branch, and the controlled terminal of the switching transistor. The output terminal of the first voltage regulator branch is grounded. The input terminal of the second voltage regulator branch is connected to the output terminal of the switching transistor and the control terminal of the switching power supply integrated module. The input terminal of the primary-side absorption branch is connected to the first power supply terminal, and the output terminal of the primary-side absorption branch is connected to the input terminal of the high-frequency transformer.

5. The electricity meter according to claim 3, characterized in that, It also includes a feedback circuit, which comprises an optocoupler module, a first voltage regulation feedback module, and a second voltage regulation feedback module. The input terminal of the first voltage regulation feedback module is connected to the first output terminal of the high-frequency transformer, the output terminal of the first voltage regulation feedback module is connected to the input terminal of the optocoupler module, the output terminal of the optocoupler module is connected to the input terminal of the second voltage regulation feedback module, and the input terminal of the second voltage regulation feedback module is connected to the power supply terminal of the switching power supply integrated module.

6. The electricity meter according to claim 3, characterized in that, The AC signal conditioning circuit includes a varistor module and a filter module. The input terminal of the varistor module is connected to the power grid, the output terminal of the varistor module is connected to the input terminal of the filter module, and the output terminal of the filter module is connected to the input terminal of the rectifier circuit.

7. The electricity meter according to claim 3, characterized in that, The protection circuit includes: a noise signal filtering branch, a balanced voltage divider branch, and a first filtering branch. The input terminal of the noise signal filtering branch is connected to the output terminal of the rectifier circuit, the output terminal of the noise signal filtering branch is connected to the input terminal of the balanced voltage divider branch, the output terminal of the balanced voltage divider branch is connected to the input terminal of the first filtering branch, and the output terminal of the first filtering branch is connected to the input terminal of the DC signal conditioning circuit.

8. The electricity meter according to claim 1, characterized in that, It also includes a power supply module circuit, which includes: a first absorption resistor, a first capacitor, a first rectifier diode, and a first filter capacitor. One end of the first filter capacitor is connected to the second power supply terminal, and the other end of the first filter capacitor is grounded. One end of the first absorption resistor is connected to the second power supply terminal. The first capacitor and the first absorption resistor are connected in series. The other end of the first capacitor is connected to the input terminal of the power supply module circuit. The anode of the first rectifier diode is connected to one end of the first absorption resistor, and the cathode of the first rectifier diode is connected to the other end of the first capacitor. The output terminal of the power supply module circuit is grounded.

9. The electricity meter according to claim 1, characterized in that, The metering power supply circuit includes: a second absorption resistor, a second capacitor, a second rectifier diode, and a second filter branch. The second output terminal of the high-frequency transformer is connected to one end of the second absorption resistor and the cathode of the second rectifier diode. The second capacitor is connected in series with the second absorption resistor. The other end of the second absorption resistor is connected to the anode of the second rectifier diode. The anode of the second rectifier diode is also connected to the input terminal of the second filter branch. The input terminal of the second filter branch is also connected to a third power supply terminal. The output terminal of the second filter branch is grounded.

10. The electricity meter according to claim 1, characterized in that, The communication power supply circuit includes a rectifier absorption branch, a harmonic filter branch, and a buffer branch. The input terminal of the rectifier absorption branch is connected to the first output terminal of the high-frequency transformer, the output terminal of the rectifier absorption branch is connected to the input terminal of the harmonic filter branch, the output terminal of the harmonic filter branch is connected to the input terminal of the buffer branch, and the output terminal of the buffer branch is used to supply power to the communication module of the energy meter.

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