A magnetic latching relay unlock circuit for an electric energy meter
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-07
- Publication Date
- 2026-08-11
AI Technical Summary
[0007]本实用新型的目的在于提供一种用于电能表的磁保持继电器解锁电路，以解决现有技术中存在的电能表的磁保持继电器解锁需要微处理器、软件支持，死机无法解锁，解锁可靠性较低，成本较高的技术问题
[0019]本实用新型通过看门狗模块监测电能表的控制芯片实现磁保持继电器跳闸解锁，断开电能表的后级负载，电路简单，成本更低，同时不需要软件来驱动，不受外部电磁环境影响，相对更稳定。从而避免了电能表的控制芯片死机或晶振损坏停振时，无法对已合闸的继电器进行拉闸，导致窃电者可正常用电。
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Figure CN224625460U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electricity meter technology, and in particular to an unlocking circuit for a magnetic latching relay used in electricity meters. Background Technology
[0002] A magnetic latching relay is a special electromagnetic relay that uses a permanent magnet to maintain the state of its contacts. It requires only a pulse current to switch the switching state, eliminating the need for continuous power supply. Electricity meters are one of the basic devices for data acquisition in smart grids, undertaking the tasks of collecting, measuring, and transmitting raw electrical data. They are the foundation for information integration, analysis, optimization, and display. In a magnetic latching relay closing and opening scheme, a microcontroller control chip, a relay driver chip, and external resistors and capacitors are used. The magnetic latching relay plays a core control role in the electricity meter. The main control chip sends pulse commands to the magnetic latching relay via signal lines and sends a reverse pulse when the meter's balance is insufficient, causing the contacts to separate and cut off the circuit, significantly improving the intelligence level of the electricity meter.
[0003] In prepaid electricity meters, a "pay first, use later" mode can be realized through magnetic latching relays. The relay can be turned on and off remotely by remote command. After integrating a communication module, the electricity meter can also support automatic tripping for overdue payments and remote reconnection after payment.
[0004] However, users employ various methods to steal electricity. For example, malicious attacks can cause the electricity meter's control chip to malfunction or the crystal oscillator to stop oscillating, preventing the meter from tripping the already closed relays. This results in the meter being unable to measure electricity or disconnect the power circuit, while the thief can continue using electricity normally. Adding a microcontroller specifically for monitoring the meter's control chip, and then tripping the relays when the chip malfunctions, requires control software support, leading to low reliability and high cost.
[0005] In the process of realizing this utility model, the applicant discovered that the prior art has at least the following problems:
[0006] Unlocking the magnetic latching relay of an electricity meter requires a microprocessor and software support; if the system crashes, it cannot be unlocked, resulting in low unlocking reliability and high cost. Utility Model Content
[0007] The purpose of this invention is to provide an unlocking circuit for a magnetic latching relay in an electricity meter, thereby solving the technical problems of existing technologies where unlocking of the magnetic latching relay in electricity meters requires microprocessor and software support, is unable to unlock due to system crashes, has low unlocking reliability, and is costly. The various technical effects of the preferred technical solution provided by this invention are detailed below.
[0008] To achieve the above objectives, the present invention provides the following technical solution:
[0009] This utility model provides an unlocking circuit for a magnetic latching relay in an electricity meter, used for unlocking the magnetic latching relay after it trips. The circuit includes a watchdog module, a signal driving module, and a relay driving module. The watchdog module receives a "feed" signal and outputs a control level signal to the signal driving module via a push-pull mechanism. The transistor or MOSFET in the signal driving module receives the control level signal and sends a driving signal to the relay driving module by turning it on or off. Based on the driving signal, the relay driving module drives the magnetic latching relay to trip and unlock.
[0010] Preferably, the watchdog chip of the watchdog module is a TPV706SL1-SR. The watchdog chip includes 8 pins. The WDI pin of the watchdog chip is connected to the feed signal, and the RST pin is used to output a push-pull control level signal.
[0011] Preferably, if the WDI pin receives a continuous watchdog signal, the RST pin outputs a high level; when the power supply of the watchdog chip is lower than the reset threshold or the MR pin of the watchdog chip is input to a low level, the RST pin outputs a 200ms low level.
[0012] Preferably, the dog-feeding signal is a square wave signal, and the duration of the high or low level of the square wave signal does not exceed 1.6 seconds.
[0013] Preferably, if the WDI pin does not receive a dog feed signal, the RST pin outputs a low-level signal for 200ms.
[0014] Preferably, the signal driving module includes transistors Q1, Q2, and Q3; transistors Q1, Q2, and Q3 are PNP type transistor Q1, NPN type transistor Q2, and NPN type transistor Q3, respectively; the base of transistor Q1 is connected to the RST pin of the watchdog chip, the emitter is connected to the power supply, and the collector is connected to the relay driving module; the base of transistor Q2 is connected to the RST pin of the watchdog chip, the emitter is grounded, and the collector is connected to the power supply and the base of transistor Q3; the emitter of transistor Q3 is grounded, and the collector is connected to the relay driving module.
[0015] Preferably, the signal driving module includes MOSFETs Q4 and Q5, and transistor Q6. MOSFETs Q4 and Q5 are PMOS transistors, and transistor Q6 is an NPN transistor. The gate of MOSFET Q4 is connected to the RST pin of the watchdog chip, its source is connected to the power supply, and its drain is connected to the relay driving module. The gate of MOSFET Q5 is connected to the RST pin of the watchdog chip, its source is connected to the power supply, and its drain is connected to the base of transistor Q6. The emitter of transistor Q6 is grounded, and its collector is connected to the relay driving module.
[0016] Preferably, the relay driver chip of the relay driver module is AL868, and pins 3 and 6 of the relay driver chip are connected to the signal driver module, while pins 1 and 4 are connected to the relay.
[0017] Preferably, when pins 3 and 6 are simultaneously input with a high or low level, pins 1 and 4 are both in a high-impedance state, and the magnetic latching relay is inactive; when pins 3 and 6 are respectively at a high and low level, pins 1 and 4 are also respectively at a high and low level, and the magnetic latching relay trips and unlocks; when pins 3 and 6 are respectively at a low and high level, pins 1 and 4 are also respectively at a low and high level, and the magnetic latching relay closes.
[0018] Implementing one of the above-described technical solutions of this utility model has the following advantages or beneficial effects:
[0019] This invention uses a watchdog module to monitor the control chip of the electricity meter, thereby tripping and unlocking the magnetic latching relay, disconnecting the downstream load of the electricity meter. The circuit is simple and lower in cost, and it does not require software to drive it, is unaffected by external electromagnetic environments, and is relatively more stable. This avoids the situation where the control chip of the electricity meter malfunctions or the crystal oscillator fails to oscillate, preventing the relay from being pulled back and allowing electricity thieves to use the electricity normally. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments 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. In the drawings:
[0021] Figure 1 This invention relates to a circuit for a watchdog module and a signal drive module in the unlocking circuit of a magnetic latching relay for an electricity meter. Figure 1 ;
[0022] Figure 2 This invention relates to a circuit for a watchdog module and a signal drive module in the unlocking circuit of a magnetic latching relay for an electricity meter. Figure 2 ;
[0023] Figure 3 This is a circuit diagram of the relay drive module in the unlocking circuit of a magnetic latching relay for an electricity meter, according to an embodiment of this utility model. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be adopted to implement this utility model. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of this utility model disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of this utility model.
[0025] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "multiple" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0026] To illustrate the technical solution described in this utility model, specific embodiments are described below, showing only the parts related to the embodiments of this utility model.
[0027] Example:
[0028] like Figures 1-3As shown, this utility model provides an unlocking circuit for a magnetic latching relay in an electricity meter, used for unlocking the magnetic latching relay after it trips. It includes a watchdog module, a signal drive module, and a relay drive module. The watchdog module receives a feed signal, which is a reset pulse or specific command periodically sent to the watchdog module. When the electricity meter is working normally, the feed signal is continuously generated. If the control chip of the electricity meter encounters a power theft attack and malfunctions or the crystal oscillator stops oscillating, it cannot continuously generate the feed signal and will push-pull out a control level signal to the signal drive module, thus achieving deterministic level drive. After receiving the control level signal, the transistor or MOSFET of the signal drive module sends a drive signal to the relay drive module by turning it on or off. Based on the drive signal, the relay drive module drives the magnetic latching relay to trip and unlock. This drive signal can also cause the magnetic latching relay to close or not perform any operation. This embodiment uses a watchdog module to monitor the control chip of the electricity meter to achieve the tripping and unlocking of the magnetic latching relay, disconnecting the downstream load of the electricity meter. The circuit is simple and lower in cost. Furthermore, it does not require software to drive it, is unaffected by the external electromagnetic environment, and is relatively more stable, effectively preventing electricity theft. This avoids the situation where the electricity meter's control chip malfunctions or the crystal oscillator fails to oscillate, preventing the relay from tripping and thus preventing the electricity meter from measuring and disconnecting the power circuit, allowing electricity thieves to use electricity normally.
[0029] As an optional implementation, the watchdog chip in the watchdog module is model TPV706SL1-SR. The TPV706SL1-SR chip has low cost and ultra-low power consumption, with an operating current as low as 4μA. Therefore, this embodiment will not generate much additional power consumption during long-term use after configuration. It has an ultra-wide operating temperature range of -40℃ to +125℃, making it suitable for use in various working environments. It features a fixed 1.6S watchdog timeout and a 200ms timeout reset, facilitating rapid tripping and unlocking of the magnetic latching relay. The TPV706SL1-SR watchdog chip includes 8 pins. The WDI pin (pin 6) of the watchdog chip receives the feed signal, and the RST pin (pin 7) outputs a push-pull control level signal. In this embodiment, the VCC pin (pin 2) is the power supply pin, and the 3.3V power supply is connected to the VCC pin through resistor R1 and capacitor C1; the GND pin (pin 3) is grounded; the FPI pin (pin 4) is the power fault detection pin, which is not used in this embodiment and can be connected to the GND pin; the FPO pin (pin 5) is the power fault detection output, which is not used in this embodiment; the WDO pin (pin 8) outputs a watchdog signal. When the WDI pin continuously receives a watchdog signal, this pin outputs a high level. When WDI remains high or low for more than 1.6 seconds, the WDO input is low; the MR pin (pin 1) is the manual reset input pin. The WDO pin is connected to the input through resistor R2, so when the WDO pin is high, the MR pin is also high, and when the WDO pin is low, the MR pin is also low.
[0030] As an optional implementation, if the WDI pin receives a continuous watchdog signal, the RST pin outputs a high level; if the WDI pin does not receive a watchdog signal, such as when the control chip of the energy meter malfunctions or the crystal oscillator stops oscillating, the RST pin outputs a 200ms low-level signal. When the power supply of the watchdog chip is lower than the reset threshold or the MR pin of the watchdog chip is input with a low level, the RST pin outputs a 200ms low level. Based on the high and low levels output by the RST pin, different controls for opening and closing the magnetic latching relay can be achieved.
[0031] As an optional implementation, the dog-feeding signal is a square wave signal, and the duration of the high or low level of the square wave signal does not exceed 1.6 seconds. This square wave signal can be generated by existing technology, so that the TPV706SL1-SR chip can maintain normal operation.
[0032] As an optional implementation method, such as Figure 1As shown, the signal driving module includes transistors Q1, Q2, and Q3; transistors Q1, Q2, and Q3 are PNP type, NPN type, and NPN type, respectively; the base of transistor Q1 is connected to the RST pin of the watchdog chip, the emitter is connected to the power supply, and the collector is connected to the relay driving module; the base of transistor Q2 is connected to the RST pin of the watchdog chip, the emitter is grounded, and the collector is connected to the power supply and the base of transistor Q3; the emitter of transistor Q3 is grounded, and the collector is connected to the relay driving module. When the electricity meter is working normally, the watchdog chip's WDI pin receives a continuous feed signal, the watchdog chip's RST pin outputs a high level, transistor Q1 is cut off, transistor Q2 is turned on, and transistor Q3 is cut off. Since transistors Q1 and Q3 are both cut off, the levels of the RLYA and RLYB signal lines are unaffected, and the magnetic latching relay does not operate. When the electricity meter's microprocessor crashes or the crystal oscillator fails and stops oscillating, the watchdog chip's WDI pin receives no feed signal input. After maintaining a high or low level for more than 1.6 seconds, the WDI pin outputs a low level, the MR pin inputs a low level, the watchdog chip's RST pin outputs a 200ms low-level signal, transistor Q1 turns on, the RLYA signal line is high, transistor Q2 is cut off, transistor Q3 turns on, and the RLYB signal line is low. At this time, the magnetic latching relay is driven to disconnect, thus tripping and unlocking the magnetic latching relay.
[0033] As an optional implementation method, such as Figure 2 As shown, the signal driving module includes MOSFETs Q4 and Q5, and transistor Q6. MOSFETs Q4 and Q5 are PMOS transistors, and transistor Q6 is an NPN transistor. The gate of MOSFET Q4 is connected to the RST pin of the watchdog chip, the source is connected to the power supply, and the drain is connected to the relay driving module. The gate of MOSFET Q5 is connected to the RST pin of the watchdog chip, the source is connected to the power supply, and the drain is connected to the base of transistor Q6. The emitter of transistor Q6 is grounded, and the collector is connected to the relay driving module. When the microprocessor of the electricity meter crashes or the crystal oscillator fails and stops oscillating, the watchdog chip's WDI pin receives no feed signal input. After maintaining a high or low level for more than 1.6 seconds, the WDO pin outputs a low level, the MR pin inputs a low level, the watchdog chip's RST pin outputs a 200ms low-level signal, MOSFET Q4 turns on, the RLYA signal line is high, MOSFET Q5 turns on, transistor Q6 turns on, and the RLYB signal line is low. At this time, the magnetic latching relay is driven to disconnect, thus tripping and unlocking the magnetic latching relay.
[0034] As an optional implementation method, such as Figure 3As shown, the relay driver chip in the relay driver module is model AL868. The AL868 chip is a bidirectional relay driver chip from Shanghai Aolong Electronics, capable of combining and switching input levels to perform different control operations on the magnetic latching relay, such as opening and closing. The AL868 chip operates within a voltage range of 5–36V and features high output current and extremely low static power consumption, facilitating bidirectional control of the magnetic latching relay. Pins 3 and 6 of the relay driver chip connect to the signal driver module, pins 1 and 4 connect to the relay, and two of these pins correspond to the live and neutral wires of the AC power supply. Pin 2 is grounded, and pin 5 is connected to the 12V power supply.
[0035] As an optional implementation, when pins 3 and 6 are simultaneously input with a high or low level, pins 1 and 4 are both in a high-impedance state, and the magnetic latching relay does not operate; when pins 3 and 6 are respectively high and low, pins 1 and 4 are also respectively high and low, and the magnetic latching relay trips and unlocks; when pins 3 and 6 are respectively low and high, pins 1 and 4 are also respectively low and high, and the magnetic latching relay closes. Through the above combinations, different types of control operations on the magnetic latching relay are realized, which can further expand the applicable scenarios of this embodiment.
[0036] The embodiment is merely a special case and does not indicate that this utility model is implemented in such a way.
[0037] The above description is merely a preferred embodiment of the present utility model. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present utility model. Furthermore, under the teachings of the present utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present utility model. Therefore, the present utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present utility model.
Claims
1. A magnetic latching relay unlocking circuit for an electricity meter, characterized in that, The device is used to unlock the magnetic latching relay of an electricity meter after it trips. It includes a watchdog module, a signal drive module, and a relay drive module. The watchdog module receives a watchdog signal and outputs a control level signal to the signal drive module via a push-pull mechanism. After receiving the control level signal, the transistor or MOSFET of the signal drive module sends a drive signal to the relay drive module by turning it on or off. Based on the driving signal, the relay driving module drives the magnetic latching relay to trip and unlock.
2. The magnetic latching relay unlocking circuit for an electricity meter according to claim 1, characterized in that, The watchdog chip of the watchdog module is model TPV706SL1-SR. The watchdog chip includes 8 pins. The WDI pin of the watchdog chip is connected to the feed signal, and the RST pin is a push-pull output control level signal.
3. The magnetic latching relay unlocking circuit for an electricity meter according to claim 2, characterized in that, If the WDI pin receives a continuous watchdog signal, the RST pin outputs a high level; when the power supply of the watchdog chip is lower than the reset threshold or the MR pin of the watchdog chip is low, the RST pin outputs a 200ms low level.
4. The unlocking circuit for a magnetic latching relay in an energy meter according to claim 2, characterized in that, The dog-feeding signal is a square wave signal, and the duration of the high or low level of the square wave signal does not exceed 1.6 seconds.
5. The unlocking circuit for a magnetic latching relay in an electricity meter according to claim 2, characterized in that, If the WDI pin does not receive a dog feed signal, the RST pin outputs a low-level signal for 200ms.
6. A magnetic latching relay unlocking circuit for an electricity meter according to any one of claims 2-5, characterized in that, The signal driving module includes transistors Q1, Q2, and Q3; transistors Q1, Q2, and Q3 are PNP, NPN, and NPN transistors, respectively; the base of transistor Q1 is connected to the RST pin of the watchdog chip, its emitter is connected to the power supply, and its collector is connected to the relay driving module; the base of transistor Q2 is connected to the RST pin of the watchdog chip, its emitter is grounded, and its collector is connected to the power supply and the base of transistor Q3; the emitter of transistor Q3 is grounded, and its collector is connected to the relay driving module.
7. A magnetic latching relay unlocking circuit for an electricity meter according to any one of claims 2-5, characterized in that, The signal driving module includes MOSFETs Q4 and Q5, and transistor Q6. MOSFETs Q4 and Q5 are PMOS transistors, and transistor Q6 is an NPN transistor. The gate of MOSFET Q4 is connected to the RST pin of the watchdog chip, its source is connected to the power supply, and its drain is connected to the relay driving module. The gate of MOSFET Q5 is connected to the RST pin of the watchdog chip, its source is connected to the power supply, and its drain is connected to the base of transistor Q6. The emitter of transistor Q6 is grounded, and its collector is connected to the relay driving module.
8. The unlocking circuit for a magnetic latching relay in an electricity meter according to claim 1, characterized in that, The relay driver chip of the relay driver module is model AL868. Pins 3 and 6 of the relay driver chip are connected to the signal driver module, and pins 1 and 4 are connected to the relay.
9. The unlocking circuit for a magnetic latching relay in an electricity meter according to claim 8, characterized in that, When pins 3 and 6 are simultaneously input with a high or low level, pins 1 and 4 are both in a high-impedance state, and the magnetic latching relay is inactive; when pins 3 and 6 are respectively at a high and low level, pins 1 and 4 are also respectively at a high and low level, and the magnetic latching relay trips and unlocks; when pins 3 and 6 are respectively at a low and high level, pins 1 and 4 are also respectively at a low and high level, and the magnetic latching relay closes.