Anti-surge microminiature ammeter based on LC filtering

Abstract

The utility model relates to an anti-surge microminiature ammeter based on LC filtering, and belongs to the field of household metering ammeters. The electric meter comprises an LC filtering module, an analog-to-digital conversion module, a metering module, a microprocessor, a storage module, a display module and a communication module. The LC filtering module, the analog-to-digital conversion module, the metering module and the microprocessor are connected in sequence; the microprocessor is also respectively connected with the storage module, the display module and the communication module; the LC filter module comprises a first-order LC filter circuit, a second-order LC filter circuit, a protection circuit and an amplification circuit which are connected in sequence; wherein the first-order LC filter circuit is in cascade connection with the second-order LC filter circuit. According to the utility model, high-frequency interference and surge voltage introduced from a power grid can be filtered, the accuracy of electric energy metering is ensured, the stability and durability of the ammeter are enhanced, and in addition, the final filtering result can ensure that the carrier communication frequency after filtering accords with the broadband carrier frequency range specified by the state grid.

Description

Technical Field

[0001] The utility model belongs to the field of household metering electric meters and relates to a surge-resistant micro-miniature electric meter based on LC filtering. Background Art

[0002] As a key device for measuring power consumption, the electric meter plays an important role in modern power systems. With the development and application of smart grids, higher requirements are imposed on the accuracy, stability, and reliability of electric meters. Especially in some complex or harsh power environments, such as large transient fluctuations in the power grid and frequent occurrence of surge currents, most of the traditional electric meters on the market are vulnerable to interference, resulting in increased measurement errors or even damage. A surge, also known as transient overvoltage / overcurrent, is usually caused by events such as lightning strikes, power grid operations, startup or shutdown of large electrical equipment. These instantaneous energy pulses far exceed the levels under normal operating conditions and pose a serious threat to the electric meter circuit, potentially leading to a decrease in measurement accuracy, damage to components, and even paralysis of the entire system. Therefore, the development of electric meters with surge-resistant capabilities has become a key point in current research and application. Content of the Utility Model

[0003] In view of this, the purpose of the utility model is to provide a surge-resistant micro-miniature electric meter based on LC filtering, which can protect the electric meter in the scenario of instantaneous large current / voltage, and realizes the miniaturization of the electric meter through a highly integrated circuit structure to meet the special requirements of small volume.

[0004] To achieve the above purpose, the utility model provides the following technical solutions:

[0005] A surge-resistant micro-miniature electric meter based on LC filtering includes an LC filtering circuit, an analog-to-digital conversion module, a metering module, a microprocessor, a storage module, a display module, and a communication module. Among them, the LC filtering circuit, the analog-to-digital conversion module, the metering module, and the microprocessor are connected in sequence; the microprocessor is also respectively connected to the storage module, the display module, and the communication module.

[0006] The LC filtering circuit includes a first-order LC filtering circuit, a second-order LC filtering circuit, a protection circuit, and an amplifier circuit connected in sequence; the first-order LC filtering circuit and the second-order LC filtering circuit are cascaded.

[0007] Among them, the first-order LC filter circuit includes resistors R1 to R4, capacitors C1 to C2, and inductor L1; the first end of resistor R2 is connected to the circuit signal, and the second end is connected to the first end of capacitor C1; the first end of resistor R4 is connected to the circuit signal, and the second end is connected to the first end of capacitor C2; both ends of inductor L1 are respectively connected to the second ends of capacitor C1 and capacitor C2; the first end of resistor R1 is grounded, and the second end is connected between resistor R2 and capacitor C1; the first end of resistor R3 is grounded, and the second end is connected between resistor R4 and capacitor C2.

[0008] The second-order LC filter circuit includes capacitors C3 to C8, inductors L2 to L3, and resistor R5; the first end of capacitor C3 is connected to the second end of capacitor C1, and the second end of capacitor C3 is connected to the first end of inductor L2; the second end of inductor L2 is connected to the first end of capacitor C4, and the second end of capacitor C4 outputs a signal to the protection circuit; the first end of capacitor C7 is connected to the second end of capacitor C2, and the second end of capacitor C7 is connected to the first end of inductor L3; the second end of inductor L3 is connected to the first end of capacitor C8, and the second end of capacitor C8 outputs a signal to the protection circuit; both ends of capacitor C5 are respectively connected to the second ends of capacitor C3 and C7; both ends of capacitor C6 are respectively connected to the second ends of inductor L2 and L3; both ends of resistor R5 are respectively connected to the second ends of inductor L2 and L3.

[0009] Optionally, the electric meter further includes a varistor / thermistor circuit, which is connected to the household circuit signal and transmitted to the LC filter circuit.

[0010] Optionally, the electric meter further includes a power supply module, which is respectively connected to the LC filter circuit, the analog-to-digital conversion module, the metering module, the microprocessor, the storage module, the display module, and the communication module for power supply.

[0011] Optionally, the varistor / thermistor circuit, the power supply module, the LC filter circuit, the analog-to-digital conversion module, the metering module, the microprocessor, the storage module, the display module, and the communication module can be integrated on a PCB board and encapsulated in a housing.

[0012] The beneficial effects of the present utility model are as follows:

[0013] (1) The present utility model can effectively resist the surge impact caused by lightning, power grid operation, heavy equipment startup, etc., and protect the electric meter itself and the subsequent circuit from damage. The surge protection mechanism reduces the equipment failure rate caused by voltage spikes.

[0014] (2) The present utility model can maintain the accuracy of metering and the stability of system operation under the condition of unstable power grid voltage or transient overvoltage, and reduce the misoperation or data error caused by voltage fluctuation.

[0015] (3) The present utility model protects the precision electronic components inside the electricity meter from damage by absorbing and dispersing surge energy, thereby extending the service life of the electricity meter and other connected electrical equipment, reducing maintenance costs and replacement frequencies.

[0016] (4) The present utility model can reduce the fire risk and other safety hazards caused by electrical surges, ensuring the safety of users and facilities.

[0017] (5) The present utility model is a surge-resistant electricity meter that complies with international standards such as IEC 61000-4-5, ensuring its compatibility and compliance globally and being applicable to various electrical environments.

[0018] (6) In a circuit connected to sensitive electronic devices (such as smart home systems, precision instruments, etc.), the present utility model can provide front-end protection for these devices to prevent them from being damaged by electrical surges.

[0019] Other advantages, objectives, and features of the present utility model will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present utility model. The objectives and other advantages of the present utility model can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the objectives, technical solutions, and advantages of the present utility model clearer, the present utility model will be described in detail preferably with reference to the accompanying drawings, where:

[0021] Figure 1 is the design principle of the LC filter circuit;

[0022] Figure 2 is the LC filter circuit diagram;

[0023] Figure 3 is the schematic diagram of the configuration of varistor / thermistor in the electricity meter circuit;

[0024] Figure 4 is the varistor / thermistor circuit diagram;

[0025] Figure 5 is the Bode plot of the filter circuit;

[0026] Figure 6 is the circuit framework diagram of the electricity meter of the present utility model;

[0027] Figure 7 is the schematic diagram of the outer shell structure of the electricity meter of the present utility model, Figure 7 (a) is the front view, Figure 7 (b) is the side view, Figure 7 (c) is the bottom view;

[0028] Figure 8 For Figure 7 the three-dimensional exploded view of the shown housing.

[0029] Reference numerals: 100 - base; 200 - housing; 210 - first fixed cover; 220 - second fixed cover; 230 - wire plug-in interface; 240 - communication interface; 300 - guide rail groove; 310 - guide rail hook; 320 - guide rail hook groove; 400 - terminal; 410 - terminal block; 500 - PCB board support; 600 - display panel groove. Specific embodiments

[0030] The following uses specific specific examples to illustrate the implementation manners of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that the drawings provided in the following embodiments only schematically illustrate the basic concept of the present utility model. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0031] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present utility model; in order to better illustrate the embodiments of the present utility model, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0032] In the drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] The utility model applies LC filtering technology to the design of micro - sized electric meters, mainly focusing on the input power line and signal transmission path. Through the designed LC filtering circuit, high - frequency interference and surge voltage introduced from the power grid can be filtered out, ensuring the accuracy of electric energy metering, and enhancing the stability and durability of the electric meter. In addition, the final result of filtering can also ensure that the filtered carrier communication frequency meets the broadband carrier frequency range (1 MHz - 30 MHz) specified by the State Grid.

[0034] As Figure 1 and Figure 2 shown, the LC filtering circuit for surge - resistant electric meters provided by an embodiment of the utility model can perform a series of processing such as low - frequency filtering and LC filtering on the PLC signal after coupling processing by integrating multiple high - efficiency LC filtering components and related circuit signal processing components within a limited circuit space, so as to filter out high - frequency signals and some low - frequency noises, achieving the effects of eliminating noises and resisting high - frequency impacts (resisting surges). In the LC filtering circuit, high - performance ceramic capacitors and miniaturized inductors are used for circuit elements, and multilayer circuit board design technology is adopted to improve circuit performance. The signal processing process of this LC filtering circuit is as follows:

[0035] 1) In the input processing circuit, low - frequency noises in the coupled zero - line and live - line circuit signals are filtered out; among them, the input processing circuit is a transformer;

[0036] 2) Unwanted high - frequency noises or interference signals are filtered out through two consecutive LC filtering sub - circuits;

[0037] 3) In the protection sub - circuit, clamping diodes are used to limit large current / voltage, preventing excessive current / voltage from causing losses to the overall circuit of the electric meter, thereby ensuring circuit safety;

[0038] 4) The overall circuit signal is amplified through an amplifier circuit and transmitted to the carrier communication module.

[0039] In this embodiment, according to the working frequency range of the electric meter and the expected immunity requirements, appropriate inductance values and capacitance values are selected to achieve the best filtering effect. Specifically, the capacitance (C) value is selected as 2.2 nF, and the inductance (L) value is selected as 15 μH. As Figure 5 shown in the Bode plot, based on the selected capacitance value and inductance value, the effective frequency range of the band - pass filtering circuit is 1 MHz - 13 MHz.

[0040] The utility model also adds varistor / thermistor design on the basis of LC filtering, as Figure 3 and Figure 4As shown in the figure, it is a varistor / thermistor circuit provided by an embodiment of the present utility model. Among them, the varistor / thermistor is arranged before the signal input end of the LC filter circuit. Under normal working conditions, the varistor presents a high-resistance state and does not affect the normal operation of the circuit. When an overvoltage appears in the circuit, the varistor quickly changes to a low-resistance state, clamping the overvoltage at a safe level, thereby protecting the subsequent circuit from damage. The thermistor is mainly used for the heat generated during the surge absorption process to ensure that the electric meter can still maintain stable performance during long-term operation. In this embodiment, a PTC thermistor is used. Such a resistor will increase its resistance value correspondingly as the temperature rises, preventing the circuit from overheating and effectively offsetting the impact brought by the instantaneous high voltage to the circuit.

[0041] The present utility model further includes a microprocessor, a metering module, a storage module, a communication module, a display module, a power supply module, and an analog-to-digital conversion module. Among them, the input end of the analog-to-digital conversion module is connected to the output end of the LC filter module, the output end of the analog-to-digital conversion module is connected to the input end of the metering module, the output end of the metering module is connected to the microprocessor, and the microprocessor is simultaneously connected to the storage module, the display module, and the communication module, as Figure 6 shown. In an embodiment of the present utility model, the microprocessor is selected as Cortex M4 and is used for processing data. In addition, in the embodiment, the data of the electric meter can also be read through the RS485 high-speed serial port, providing more diverse data acquisition methods.

[0042] In an embodiment of the present utility model, the LC filter circuit, the varistor / thermistor, the analog-to-digital conversion module, the metering module, the microprocessor, the storage module, the communication module, the display module, and the power supply module are integrated on a PCB board and encapsulated in the Figure 7 and Figure 8 mentioned housing. The overall size of the housing can reach 82×36×50mm, realizing the miniaturized design of the electric meter and being able to be flexibly applied to some scenarios with smaller installation spaces. The electric meter can fix the electric meter at the place where it needs to be installed through the guide rail groove 300 of the housing, and then insert the guide rail hook 310 into the guide rail hook groove 320 to fasten the electric meter and prevent it from falling off.

[0043] In Figure 8 the shown electric meter housing, the display panel groove 600 is used to fix the display module, and the display module can use a liquid crystal display screen to display information. The plug-in interface 230, the terminal block 400, and the terminal seat 410 are used to realize the connection with the household circuit for metering. The communication interface 240 is for the RS485 serial port line to enter and exit. The PCB board support column 500 is used to fix the PCB board.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A surge-resistant miniature electric meter based on LC filtering, characterized in that: It includes an LC filtering module, an analog-to-digital conversion module, a metering module, a microprocessor, a storage module, a display module and a communication module; the LC filtering module, the analog-to-digital conversion module, the metering module and the microprocessor are connected in sequence; the microprocessor is also connected to the storage module, the display module and the communication module respectively; the LC filtering module includes a first-order LC filtering circuit, a second-order LC filtering circuit, a protection circuit and an amplifying circuit connected in sequence; the first-order LC filtering circuit is cascaded with the second-order LC filtering circuit.

2. The surge-resistant miniature electric meter according to claim 1, characterized in that: The first-order LC filter circuit includes resistors R1-R4, capacitors C1-C2 and inductor L1; the first end of resistor R2 is connected to the circuit signal, and the second end is connected to the first end of capacitor C1; the first end of resistor R4 is connected to the circuit signal, and the second end is connected to the first end of capacitor C2; the two ends of inductor L1 are respectively connected to the second ends of capacitor C1 and capacitor C2; the first end of resistor R1 is grounded, and the second end is connected between resistor R2 and capacitor C1; the first end of resistor R3 is grounded, and the second end is connected between resistor R4 and capacitor C2; The second-order LC filter circuit includes capacitors C3 to C8, capacitors L2 to L3 and a resistor R5; the first end of capacitor C3 is connected to the second end of capacitor C1, and the second end of capacitor C3 is connected to the first end of inductor L2; the second end of inductor L2 is connected to the first end of capacitor C4, and the second end of capacitor C4 outputs a signal to the protection circuit; the first end of capacitor C7 is connected to the second end of capacitor C2, and the second end of capacitor C7 is connected to the first end of inductor L3; the second end of inductor L3 is connected to the first end of capacitor C8, and the second end of capacitor C8 outputs a signal to the protection circuit; the two ends of capacitor C5 are respectively connected to the second ends of capacitors C3 and C7; the two ends of capacitor C6 are respectively connected to the second ends of inductors L2 and L3; the two ends of resistor R5 are respectively connected to the second ends of inductors L2 and L3.

3. The surge-resistant miniature electric meter according to claim 1, characterized in that: It also includes a varistor / thermistor circuit, which is connected to the household circuit signal and transmitted to the LC filter module.

4. The surge-resistant miniature electric meter according to claim 1, characterized in that: It also includes a power supply module, which is respectively connected to the LC filter module, the analog-to-digital conversion module, the metering module, the microprocessor, the storage module, the display module and the communication module for power supply.

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