Communication module built-in electric energy meter

Abstract

The utility model discloses a kind of electric energy meter with communication module built-in, including watch case, main control board, communication module and power supply part are installed in the watch case.The transformer of the power supply part is equipped with first secondary winding and second secondary winding, the reference ground of first secondary winding connects the N line of power grid, first secondary winding is powered for main control board by main control power supply module, the reference ground of second secondary winding connects floating ground plane, second secondary winding is powered for communication module by communication power supply module.The utility model sets up mutually isolated main control power supply module and communication power supply module, and using the second secondary winding of reference ground connection floating ground plane for communication module power supply, so that the power supply loop of communication module and the strong current loop of main control board are completely isolated, effectively avoid electric shock accident, reduce the safety hidden danger of built-in communication module when maintaining.

Description

Technical Field

[0001] This utility model belongs to the field of power equipment, and specifically relates to an electricity meter. Background Technology

[0002] Smart meters, as key devices for electricity metering and data acquisition, are typically equipped with communication modules to enable remote data transmission and fee control functions. In traditional designs, the communication module is often an external structure separate from the main body of the meter, with electrical connections achieved via pin sockets. However, this type of split structure has significant shortcomings in terms of waterproofing and dustproofing, and the interface is prone to degradation of protective performance due to structural gaps. To improve this situation, existing technologies have proposed integrating the communication module while maintaining a pluggable connection structure. For example, Chinese Utility Model Patent CN215340000U discloses a single-phase local fee control smart meter that supports hot-swapping of the communication module, which features a sliding protective device on the inner surface of the main housing to protect the communication interface from dust, thus improving the interface's protection level to some extent.

[0003] While these improved structures enhance interface protection, they do not completely eliminate the inherent drawbacks of the separate connection method. Improper insertion and removal during field installation or module replacement can easily lead to mechanical interference between the pins and sockets, causing pin deformation or poor contact, affecting communication reliability and long-term operational stability. Furthermore, the added protective devices are typically complex in structure, increasing manufacturing costs and making them prone to wear or failure during frequent insertion and removal, potentially introducing new points of failure.

[0004] To further enhance the overall protection and connection reliability of the device, existing technologies have also explored the design approach of replacing the communication module with a built-in, non-removable integrated structure, only providing an interface for replacing the SIM card and a corresponding sealing cover for easy replacement and maintenance. Since mature structural solutions exist for both the SIM card slot and the sealing cover, this approach can significantly improve the dust and water resistance of the electricity meter while controlling costs, avoiding mechanical damage caused by repeated insertions and removals, and eliminating compatibility issues caused by differences in interface parameters between communication modules from different manufacturers. However, this structure also introduces new safety hazards: when replacing the SIM card, maintenance personnel need to open the sealing cover to access the circuit board of the communication module, potentially exposing themselves to high-voltage components on the circuit board, posing a risk of electric shock. Utility Model Content

[0005] This utility model proposes a power meter built into a communication module, the purpose of which is to solve the problem of serious electric shock accidents caused by maintenance personnel accidentally touching high-voltage parts when replacing SIM cards.

[0006] The technical solution of this utility model is as follows: A power meter with a built-in communication module includes a casing. A main control board and a power supply unit are installed inside the casing. The power supply unit includes a transformer and a main control power supply module. The transformer has a primary winding, the reference ground of which is connected to the neutral (N) line of the power grid. The primary winding supplies power to the main control board through the main control power supply module. The power meter also includes a communication module for implementing communication functions. The communication module is electrically connected to the main control board to supply power to the communication module and facilitate communication between the main control board and the communication module. The power supply unit further includes a communication power supply module. The transformer also has a secondary winding, the reference ground of which is connected to a floating ground plane. The secondary winding supplies power to the communication module through the communication power supply module. The communication module is a communication circuit board, which is arranged parallel to the front of the main control board and mounted on the main control board through an isolation column; the main control board and the communication circuit board are electrically connected through a board-to-board connector.

[0007] As a further improvement to the energy meter built into the communication module: an operation window corresponding to the position of the communication circuit board is opened on the front side of the meter casing, an operation cover is installed on the operation window, and a sealing device is provided between the operation cover and the operation window.

[0008] As a further improvement to the energy meter built into the communication module: the communication power supply module includes a step-down converter D17; The positive terminal of the second stage winding is connected to the VIN pin of the buck converter D17, the reference ground of the second stage winding is connected to the GND pin of the buck converter D17, the VOUT pin of the buck converter D17 is connected to the positive terminal of the diode V73, and the negative terminal of the diode V73 is used to output the first communication power supply.

[0009] As a further improvement to the energy meter built into the communication module: the LDO pin of the buck converter D17 is used to output a second communication power supply. The LDO pin is also connected to the reference ground of the secondary winding via series resistors R137 and R143; the connection point between resistors R137 and R143 is connected to the FB pin of the buck converter D17.

[0010] As a further improvement to the energy meter built into the communication module, capacitors C101 and C14 are connected in parallel between the LDO pin and the reference ground of the secondary winding.

[0011] As a further improvement to the energy meter built into the communication module: a capacitor C117 is also connected between the VOUT pin of the buck converter D17 and the reference ground of the secondary winding. A parallel capacitor C115 and a capacitor C116 are connected between the negative terminal of diode V73 and the reference ground of the secondary winding.

[0012] As a further improvement to the energy meter built into the communication module, the main control board is also provided with an optocoupler signal isolation circuit, through which the first signal transceiver circuit on the main control board is communicatively connected to the second signal transceiver circuit located on the communication circuit board.

[0013] As a further improvement to the energy meter built into the communication module: the optocoupler signal isolation circuit includes a receiving section; The receiving section includes an optocoupler E9 and an NPN transistor V25; The positive terminal of the input of optocoupler E9 is connected to the positive terminal of the output of the communication power supply module, and the negative terminal is connected to the signal transmitting terminal SM_TXD of the second signal transceiver circuit through resistor R83. The collector of the output terminal of optocoupler E9 is connected to the positive terminal of the main control power supply module, and is also connected to the signal receiving terminal MCU_RXD of the first signal transceiver circuit through resistor R82; the signal receiving terminal MCU_RXD is connected to the collector of NPN transistor V25. The emitter of the output terminal of optocoupler E9 is connected to the reference ground of the primary winding through resistor R199, and is also connected to the base of NPN transistor V25 through resistor R204; the emitter of NPN transistor V25 is connected to the reference ground of the primary winding.

[0014] As a further improvement to the energy meter built into the communication module: the optocoupler signal isolation circuit includes a transmitting section; The transmitting section includes an optical coupler E11; The positive input terminal of optocoupler E11 is connected to the positive output terminal of the main control power supply module, and the negative terminal is connected to the signal transmitting terminal MCU_TXD of the first signal transceiver circuit through resistor R86. The output collector of optocoupler E11 is connected to the positive output of the communication power supply module, and the negative output is connected to the signal receiving terminal SM_RXD of the second signal transceiver circuit.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This utility model features a mutually isolated main control power supply module and communication power supply module. The communication module is powered by a secondary winding connected to a floating ground plane, ensuring complete isolation between the communication module's power supply circuit and the main control board's high-voltage circuit. When maintenance personnel open the operating cover to replace the SIM card, even if they touch live parts on the communication circuit board, the absence of a direct circuit between its potential and ground effectively prevents electric shock accidents, reducing safety hazards during maintenance of the built-in communication module.

[0016] 2. The communication circuit board is mounted parallel to the front of the main control board via isolation pillars and is electrically connected using board-to-board connectors. This structure ensures reliable communication between the two while maintaining sufficient electrical clearance and creepage distance, ensuring the withstand voltage between the communication module and the high-voltage parts of the main control board, and further improving the safety and reliability of the equipment.

[0017] 3. The communication power supply module adopts a circuit structure that includes a step-down converter, which can output two stable communication power supplies. By arranging multiple filter capacitors at key nodes, it effectively suppresses power ripple, providing a clean and high-quality operating power supply for the communication module, ensuring the stability of the communication process and the accuracy of data transmission.

[0018] 4. This utility model also includes an optocoupler signal isolation circuit between the main control board and the communication circuit board, achieving electrical isolation of signal transmission and completely blocking potential interference from the high-voltage components to the communication circuit. This isolation circuit further incorporates an NPN transistor in the receiving section, effectively eliminating erroneous signals generated by the afterglow effect during optocoupler switching, ensuring clear and complete signal edges, thereby supporting higher-speed and more reliable data communication. Attached Figure Description

[0019] Figure 1 This is a view of the exterior of the present utility model; Figure 2 A diagram showing the communication circuit board mounted on the main control board. Figure 1 ; Figure 3 A diagram showing the communication circuit board mounted on the main control board. Figure 2 ; Figure 4 This is a schematic diagram of the transformer's structure. Figure 5 Circuit diagram for the communication power supply module; Figure 6 This is a circuit diagram of the part of the main control power supply module that converts the 12V voltage output from the primary winding to 5.6V. Figure 7 This is the circuit diagram of the optocoupler signal isolation circuit on the main control board.

[0020] Figure label: 1. Case; 2. Operating cover; 3. Main control board; 4. Communication circuit board; 5. Isolation post; 6. Board-to-board connector; 7. Primary winding; 8. Secondary winding. Detailed Implementation

[0021] The technical solution of this utility model will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0022] As attached Figures 1 to 4 As shown, this utility model provides an energy meter with a built-in communication module, including a meter housing 1, a main control board 3, a communication circuit board 4 serving as a communication module, and a power supply unit installed inside the meter housing 1.

[0023] The power supply section includes a transformer, a communication power supply module, and a main control power supply module. The transformer core has a primary winding wound on one side, and a first primary winding 7 and a second primary winding 8 on the other side. The reference ground of the first primary winding 7 is connected to the neutral (N) line of the power grid, and the first primary winding 7 supplies power to the main control board 3 through the main control power supply module. The reference ground of the second primary winding 8 is connected to the floating ground plane, and the second primary winding 8 supplies power to the communication module through the communication power supply module.

[0024] The communication circuit board 4 is electrically connected to the main control board 3 to provide power to the communication module and facilitate communication between the main control board 3 and the communication module. Specifically, for example... Figure 3 and Figure 4 The communication circuit board 4 is arranged parallel to the front side of the main control board 3 and is mounted on the main control board 3 via the isolation post 5. The main control board 3 and the communication circuit board 4 are electrically connected via a board-to-board connector 6. This structure not only achieves a reliable electrical connection between the two but also maintains sufficient electrical clearance and creepage distance, enhancing the withstand voltage.

[0025] Furthermore, such as Figure 1 The front side of the watch case 1 has an operation window corresponding to the position of the communication circuit board 4. An operation cover 2 is installed on the operation window. One end of the operation cover 2 is rotatably connected to the watch case 1, and the other end is fixed to the watch case 1 with screws. A sealing device (such as a sealing strip or sealing gasket) is provided between the operation cover 2 and the operation window to improve the dustproof and waterproof performance of the whole device.

[0026] like Figure 5The communication power supply module includes a buck converter D17. The positive terminal of the secondary winding 8 is connected to the VIN pin of the buck converter D17, the reference ground of the secondary winding 8 is connected to the GND pin of the buck converter D17, and the VOUT pin of the buck converter D17 is connected to the positive terminal of diode V73. The negative terminal of diode V73 is used to output the first communication power supply (12VCC). The LDO pin of the buck converter D17 is used to output the second communication power supply (5VCC); the LDO pin is also connected to the reference ground of the secondary winding 8 through resistors R137 and R143 in series; the connection point between resistors R137 and R143 is connected to the FB pin of the buck converter D17. Capacitors C101 and C14 are also connected in parallel between the LDO pin and the reference ground of the secondary winding 8. A capacitor C117 is connected between the VOUT pin of the buck converter D17 and the reference ground of the secondary winding 8; capacitors C115 and C116 are connected in parallel between the negative terminal of diode V73 and the reference ground of the secondary winding 8.

[0027] This circuit structure can output two stable communication power supplies and effectively suppress power supply ripple through multi-stage filtering to ensure the working quality of the communication module. Specifically, the communication module consumes a relatively high amount of power (4.2W, current reaches 1A) during operation, making its power supply quality requirements particularly stringent, and ripple must be controlled at a low level. The ripple in this circuit mainly originates from the dynamic imbalance between energy supply and demand in the switching power supply under high load conditions. To suppress ripple, this solution sets capacitors C117 (470uF electrolytic capacitor), C115 (10uF ceramic capacitor), and C116 (0.1uF ceramic capacitor) in parallel at the output of the communication power supply module. Utilizing the energy storage characteristics of capacitors, they charge and store energy when the instantaneous voltage is higher than the load demand, and discharge and replenish energy when the instantaneous voltage is lower than the load demand, thereby effectively smoothing voltage fluctuations, reducing the peak-to-peak value of the output ripple, and ensuring a clean and stable power supply for the communication module. In addition, the step-down converter D17 (specific model can be DM7803) has an integrated short-circuit protection function. If a short-circuit fault occurs in the communication module, the chip can quickly cut off the power supply output, thereby ensuring that the normal operation of the energy meter under the main control power supply is not affected.

[0028] like Figure 6 As shown, the main control power supply module includes a DC-DC converter D15, which converts the 12V power output from the primary winding 7 to 5.6V. It's important to note that the reference ground in this circuit is connected to the reference ground of the primary winding 7 (i.e., the N line). This solution also uses another DC-DC converter to convert the 5.6V power supply to 3.3V, and its circuit principle is similar. Figure 6 The same applies, so I won't go into details here.

[0029] In addition, when printing the main control board 3, it is necessary to ensure that the distance between the two sets of power-related circuits is greater than 6mm, and to ensure that it can withstand 4000V AC insulation withstand voltage.

[0030] As attached Figure 7 As shown, the main control board 3 is also equipped with an optocoupler signal isolation circuit. The first signal transceiver circuit on the main control board 3 is connected to the second signal transceiver circuit located on the communication circuit board 4 through the optocoupler signal isolation circuit, thereby isolating the power supply (3.3V) of the main control part and the power supply (5VCC) of the communication module.

[0031] Specifically, the optocoupler signal isolation circuit includes a receiving section and a transmitting section.

[0032] The receiving section includes an optocoupler E9 and an NPN transistor V25. The positive terminal of the input of optocoupler E9 is connected to the positive terminal of the output of the communication power supply module, and the negative terminal is connected to the signal transmitting terminal SM_TXD of the second signal transceiver circuit through resistor R83. The collector of the output of optocoupler E9 is connected to the positive terminal of the output of the main control power supply module, and also to the signal receiving terminal MCU_RXD of the first signal transceiver circuit through resistor R82; the signal receiving terminal MCU_RXD is connected to the collector of NPN transistor V25. The emitter of the output of optocoupler E9 is connected to the reference ground of the first stage winding 7 through resistor R199, and also to the base of NPN transistor V25 through resistor R204; the emitter of NPN transistor V25 is connected to the reference ground of the first stage winding 7.

[0033] The receiving section not only achieves electrical isolation for signal transmission but also effectively eliminates erroneous signals caused by the persistence effect during the switching process of the optocoupler by introducing an NPN transistor, ensuring the reliability of high-speed communication. Specifically, when the input signal SM_TXD changes from high to low, the LED inside optocoupler E9 conducts and emits light, and its secondary phototransistor conducts accordingly. Current flows through resistor R199 and charges the base of transistor V25. When the base voltage of V25 reaches the turn-on voltage, V25 conducts, and the output signal MCU_RXD is pulled low. When the input signal SM_TXD changes from low to high, the LED of optocoupler E9 turns off, its secondary current begins to decrease, and resistor R199 quickly pulls down the base voltage of V25, causing V25 to quickly turn off and enter the cutoff region. The output signal MCU_RXD is pulled high by the power supply V3.3V through resistor R82. This mechanism effectively eliminates the optocoupler turn-off delay, ensuring the clarity and integrity of signal edges during high-speed communication, thereby guaranteeing communication reliability.

[0034] The transmitting section includes an optocoupler E11. The positive input terminal of optocoupler E11 is connected to the positive output terminal of the main control power supply module, and the negative terminal is connected to the signal transmitting terminal MCU_TXD of the first signal transceiver circuit through resistor R86. The collector of the output terminal of optocoupler E11 is connected to the positive output terminal of the communication power supply module, and the negative terminal is connected to the signal receiving terminal SM_RXD of the second signal transceiver circuit. When MCU_TXD is low, the LED at the input terminal of optocoupler E11 is turned on and emits light, and the photosensitive element at the output terminal is turned on by the light, making the output of SM_RXD high. When MCU_TXD is high, the LED is turned off, the photosensitive element is turned off, and the output of SM_RXD is low through the pull-down resistor R91.

[0035] The working principle of this utility model is as follows: After the electricity meter is connected to the mains power, the transformer provides isolated power to the main control board 3 and the communication circuit board 4 through the primary winding 7 and the secondary winding 8, respectively. The reference ground of the secondary winding 8 is a floating ground plane, so that there is no direct loop between the potential of the communication circuit board 4 and the ground. Even if maintenance personnel touch the communication circuit board 4 when opening the operation cover 2 to replace the SIM card, no electric shock loop will be formed, ensuring operational safety. During communication, the main control board 3 and the communication circuit board 4 exchange data through the board-to-board connector 6 and the optocoupler signal isolation circuit. The design of the optocoupler isolation and the receiving end acceleration circuit effectively improves the signal transmission rate and reliability.

[0036] It should be noted that, as will be apparent to those skilled in the art, this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. The scope of this utility model is defined by the claims rather than the foregoing description.

Claims

1. A power meter with a built-in communication module, comprising a casing (1), wherein a main control board (3) and a power supply are installed inside the casing (1), the power supply comprising a transformer and a main control power supply module, the transformer having a primary winding (7), the reference ground of the primary winding (7) being connected to the N line of the power grid, the primary winding (7) being powered by the main control power supply module to the main control board (3); the power meter further comprising a communication module for realizing communication functions, the communication module being electrically connected to the main control board (3) to realize power supply to the communication module and communication between the main control board (3) and the communication module, characterized in that: The power supply section also includes a communication power supply module; the transformer is also provided with a secondary winding (8), the reference ground of the secondary winding (8) is connected to the floating ground plane, and the secondary winding (8) supplies power to the communication module through the communication power supply module; The communication module is a communication circuit board (4), which is arranged parallel to the front side of the main control board (3) and is mounted on the main control board (3) through an isolation column (5); the main control board (3) and the communication circuit board (4) are electrically connected through a board-to-board connector (6).

2. The energy meter built into the communication module as described in claim 1, characterized in that: The front side of the watch case (1) has an operation window corresponding to the position of the communication circuit board (4). An operation cover (2) is installed on the operation window, and a sealing device is provided between the operation cover (2) and the operation window.

3. The energy meter built into the communication module as described in claim 1, characterized in that: The communication power supply module includes a step-down converter D17; The positive terminal of the second stage winding (8) is connected to the VIN pin of the buck converter D17, the reference ground of the second stage winding (8) is connected to the GND pin of the buck converter D17, the VOUT pin of the buck converter D17 is connected to the positive terminal of the diode V73, and the negative terminal of the diode V73 is used to output the first communication power supply.

4. The energy meter built into the communication module as described in claim 3, characterized in that: The LDO pin of the buck converter D17 is used to output a second communication power supply. The LDO pin is also connected to the reference ground of the secondary winding (8) via series resistors R137 and R143; the connection point between resistors R137 and R143 is connected to the FB pin of the buck converter D17.

5. The energy meter built into the communication module as described in claim 4, characterized in that: A parallel capacitor C101 and a capacitor C14 are also connected between the LDO pin and the reference ground of the secondary winding (8).

6. The energy meter built into the communication module as described in claim 3, characterized in that: A capacitor C117 is also connected between the VOUT pin of the buck converter D17 and the reference ground of the secondary winding (8); A parallel capacitor C115 and a capacitor C116 are also connected between the negative terminal of diode V73 and the reference ground of the secondary winding (8).

7. The energy meter built into the communication module as described in any one of claims 1 to 6, characterized in that: The main control board (3) is also provided with an optocoupler signal isolation circuit. The first signal transceiver circuit on the main control board (3) is connected to the second signal transceiver circuit located on the communication circuit board (4) through the optocoupler signal isolation circuit.

8. The energy meter built into the communication module as described in claim 7, characterized in that: The optocoupler signal isolation circuit includes a receiving section; The receiving section includes an optocoupler E9 and an NPN transistor V25; The positive terminal of the input of optocoupler E9 is connected to the positive terminal of the output of the communication power supply module, and the negative terminal is connected to the signal transmitting terminal SM_TXD of the second signal transceiver circuit through resistor R83. The collector of the output terminal of optocoupler E9 is connected to the positive terminal of the main control power supply module, and is also connected to the signal receiving terminal MCU_RXD of the first signal transceiver circuit through resistor R82; the signal receiving terminal MCU_RXD is connected to the collector of NPN transistor V25. The emitter of the output terminal of optocoupler E9 is connected to the reference ground of the primary winding (7) through resistor R199, and is also connected to the base of NPN transistor V25 through resistor R204; the emitter of NPN transistor V25 is connected to the reference ground of the primary winding (7).

9. The energy meter built into the communication module as described in claim 7, characterized in that: The optocoupler signal isolation circuit includes a transmitting section; The transmitting section includes an optical coupler E11; The positive input terminal of optocoupler E11 is connected to the positive output terminal of the main control power supply module, and the negative terminal is connected to the signal transmitting terminal MCU_TXD of the first signal transceiver circuit through resistor R86. The output collector of optocoupler E11 is connected to the positive output of the communication power supply module, and the negative output is connected to the signal receiving terminal SM_RXD of the second signal transceiver circuit.

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