Magnetic field interference resisting module and method for magnetic latching relay of electric energy meter and terminal

Abstract

The invention discloses a magnetic field interference resisting module and method for a magnetic latching relay of an electric energy meter and a terminal. The anti-magnetic field interference module comprises an MCU, a relay drive circuit, a magnetic field intensity detection circuit and a relay anti-strong magnetic drive holding circuit. Whether the circuit is in a strong magnetic interference state or not is judged through a detection signal of the magnetic field intensity detection circuit, if strong magnetic interference exists, the driving current is increased through the relay anti-strong-magnetic driving holding circuit when the driving relay acts, and in a normal state, the driving current is increased through the relay anti-strong-magnetic driving holding circuit. And the strong-magnetic-resistance driving holding circuit of the relay is used for providing holding current for a relay coil, so that the permanent magnet magnetic flux density is increased, and the purpose of preventing misoperation of the relay is achieved.

Description

Technical Field

[0001] The invention belongs to the fields of electric energy meters and distribution terminals, and particularly relates to a magnetic holding relay anti-magnetic field interference module and method for an electric energy meter and a terminal. Background Art

[0002] The magnetic holding relay built in an electric energy meter is a core component for realizing the function of fee control. It completes the tripping and closing actions through the coordinated operation of an electromagnetic drive system and a permanent magnet magnetic circuit system. Specifically, the electromagnetic drive system consists of a coil, and an alternating magnetic field is generated by changing the direction of the coil current. The magnetic circuit system relies on a permanent magnet to provide a magnetic field in a fixed direction. When the coil is energized, if the direction of the electromagnetic field is the same as that of the permanent magnet magnetic field, the repulsive force between the two pushes the contact to close; otherwise, an attractive force is generated to disconnect the contact. This mechanism is extremely sensitive to the magnetic field environment, and external constant magnetic field interference may disrupt the magnetic circuit balance, resulting in misoperation or refusal to operate of the contact.

[0003] The influence of strong magnetic field interference on the magnetic holding relay is specifically reflected in two aspects: First, when the direction of the external magnetic field is opposite to that of the permanent magnet magnetic field, it may weaken the coercivity of the permanent magnet or even demagnetize it reversely, resulting in abnormal switching of the contact. Second, if the external magnetic field is in the same direction as the permanent magnet, the magnetic field superposition effect will enhance the contact holding force, making it unable to operate normally. In addition, the strong magnetic field will also increase the coil resistance, reduce the exciting current, and cause the relay drive to fail. Such failures may cause mis-power-off or refusal to operate, resulting in damage to user equipment or economic losses.

[0004] Traditional solutions mainly use a magnetic conductive shell cover to shield weak magnetic fields, but this method has limited protection effect on strong magnetic fields, and adding an iron shell may affect the internal heat dissipation and insulation performance of the electric energy meter, bringing potential safety hazards.

[0005] In the anti-stealing electricity circuit applied to electric energy meters and acquisition terminal products disclosed in the Chinese invention patent application with publication number CN119518607A, a solution is proposed to quantify the external magnetic field through a magnetic field intensity detection module and linearly increase the driving voltage to resist magnetic field interference. However, this solution only increases the voltage during driving to ensure normal operation, but in the normal state (non-driving state), if the interference magnetic field intensity is relatively high, there is still a situation of misoperation. Summary of the Invention

[0006] The invention provides a magnetic holding relay anti-magnetic field interference module and method for an electric energy meter and a terminal, and its purpose is to solve the problem that the magnetic holding relay is prone to misoperation due to magnetic field interference when in a static state.

[0007] The technical solution of the invention is as follows:

[0008] A magnetic holding relay anti-magnetic field interference module for an electric energy meter and a terminal, comprising an MCU and a relay driving circuit. The MCU is connected to a relay coil through the relay driving circuit, and the relay driving circuit is used to output a basic driving current to the relay coil.

[0009] The anti-magnetic field interference module further includes a magnetic field intensity detection circuit and a relay anti-strong magnetic driving and holding circuit.

[0010] The output end of the magnetic field intensity detection circuit is connected to the MCU, and is used to detect the intensity of the interference magnetic field and send a magnetic field intensity detection signal to the MCU.

[0011] The MCU is connected to the relay coil through the relay anti-strong magnetic driving and holding circuit, and the relay anti-strong magnetic driving and holding circuit is used to output an auxiliary current to the relay coil.

[0012] As a further improvement of the magnetic holding relay anti-magnetic field interference module for the electric energy meter and the terminal: The relay driving circuit includes optocoupler E1, optocoupler E2 and driving chip D1.

[0013] The input ends of optocoupler E1 and optocoupler E2 are both connected to the MCU, and respectively receive signal RelayOn and signal RelayOff.

[0014] The output ends of optocoupler E1 and optocoupler E2 are respectively connected to the IN1 input pin and IN2 input pin of the driving chip D1, and are used to control the direction of the output current between the OUT1 output pin and OUT2 output pin of the driving chip D1.

[0015] The OUT1 output pin and OUT2 output pin of the driving chip D1 are respectively connected to both ends of the relay coil.

[0016] As a further improvement of the magnetic holding relay anti-magnetic field interference module for the electric energy meter and the terminal: The positive pole of the input end of optocoupler E1 is connected to the 3.3V power supply, the negative pole of the input end receives signal RelayOn through resistor R1, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through series resistors R3 and R5, and the connection point between resistors R3 and R5 is connected to the IN1 input pin of the driving chip D1.

[0017] The positive pole of the input end of optocoupler E2 is connected to the 3.3V power supply, the negative pole of the input end receives signal RelayOff through resistor R2, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through series resistors R4 and R6, and the connection point between resistors R4 and R6 is connected to the IN2 input pin of the driving chip D1.

[0018] As a further improvement to the anti-magnetic field interference module of the magnetic latching relay for the electricity meter and the terminal: the ISET pin of the driving chip D1 is grounded through a pull-down resistor R7, and the threshold value of the output current of the driving chip D1 can be set by adjusting the resistance value of the pull-down resistor R7.

[0019] As a further improvement to the anti-magnetic field interference module of the magnetic latching relay for the electricity meter and the terminal: the relay anti-strong magnetic drive holding circuit includes optocouplers E3, E4 and a driving chip D2;

[0020] The input ends of the optocoupler E3 and the optocoupler E4 are both connected to the MCU, and respectively receive the signal RelayKeepOn and the signal RelayKeepOff;

[0021] The output ends of the optocoupler E3 and the optocoupler E4 are respectively connected to the IN1 input pin and the IN2 input pin of the driving chip D2, and are used to control the direction of the output current between the OUT1 output pin and the OUT2 output pin of the driving chip D2;

[0022] The OUT1 output pin and the OUT2 output pin of the driving chip D2 are respectively connected to both ends of the relay coil.

[0023] As a further improvement to the anti-magnetic field interference module of the magnetic latching relay for the electricity meter and the terminal: the positive pole of the input end of the optocoupler E3 is connected to the 3.3V power supply, the negative pole of the input end receives the signal RelayKeepOn through the resistor R8, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R10 and R12, and the connection point between the resistors R10 and R12 is connected to the IN1 input pin of the driving chip D2;

[0024] The positive pole of the input end of the optocoupler E4 is connected to the 3.3V power supply, the negative pole of the input end receives the signal RelayKeepOff through the resistor R9, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R11 and R13, and the connection point between the resistors R11 and R13 is connected to the IN2 input pin of the driving chip D2.

[0025] As a further improvement to the anti-magnetic field interference module of the magnetic latching relay for the electricity meter and the terminal: the ISET pin of the driving chip D2 is grounded through a pull-down resistor R14, and the threshold value of the output current of the driving chip D1 can be set by adjusting the resistance value of the pull-down resistor R14.

[0026] As a further improvement to the anti-magnetic field interference module of the magnetic latching relay for the electricity meter and the terminal: a current-limiting resistor R20 is also connected between the OUT1 output pin and / or the OUT2 output pin of the driving chip D2 and the relay coil, and is used to limit the magnitude of the output auxiliary current.

[0027] The present invention also provides an anti-magnetic field interference method based on the anti-magnetic field interference module described above: the magnetic field intensity detection circuit detects the intensity of the interfering magnetic field in real time and sends the magnetic field intensity detection signal to the MCU. The MCU determines whether it is in a strong magnetic field interference state according to the magnetic field intensity detection signal;

[0028] If it is in a strong magnetic field interference state: when the relay needs to be controlled to act, the MCU controls the relay drive circuit to output a basic drive current to the relay coil and at the same time controls the relay anti-strong magnetic drive holding circuit to output an auxiliary current in the same direction as the drive current to the relay coil. The basic drive current and the auxiliary current pass through the relay coil at the same time, increasing the drive current when the relay acts; when the relay needs to maintain its original state, the MCU controls the relay anti-strong magnetic drive holding circuit to output an auxiliary current in the same direction as the drive current during the previous action to the relay coil, and controls the relay drive circuit not to output the basic drive current.

[0029] As a further improvement of the anti-magnetic field interference method, if it is not in a strong magnetic field interference state: when the relay needs to be controlled to act, the MCU controls the relay drive circuit to output a basic drive current to the relay coil, and the relay anti-strong magnetic drive holding circuit does not output current; when the relay needs to maintain its original state, neither the relay drive circuit nor the relay anti-strong magnetic drive holding circuit outputs current.

[0030] Compared with the prior art, the present invention has the following positive effects:

[0031] 1. The present invention determines whether it is in a strong magnetic interference state through the detection signal of the magnetic field intensity detection circuit. If there is strong magnetic interference, the relay anti-strong magnetic drive holding circuit is used to increase the drive current when driving the relay to act, and under normal conditions, the relay anti-strong magnetic drive holding circuit is also used to provide a holding current for the relay coil to increase the magnetic flux density of the permanent magnet, so as to prevent the relay from malfunctioning.

[0032] 2. A current limiting resistor is connected to the output end of the relay anti-strong magnetic drive holding circuit, which can limit the magnitude of the holding current and avoid excessive current and obvious temperature rise during holding under normal conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the architecture diagram of the anti-magnetic field interference module of the present invention;

[0034] Figure 2 is the circuit diagram of the magnetic field intensity detection circuit;

[0035] Figure 3 is the circuit diagram of the MCU and its control circuit part;

[0036] Figure 4 Circuit diagram of relay drive circuit;

[0037] Figure 5 Circuit diagram of relay anti-strong magnetic drive and hold circuit. Specific implementation manner

[0038] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0039] Embodiment 1

[0040] As Figure 1 , this embodiment provides a magnetic field interference resistance module for a magnetic latching relay of an electric energy meter and a terminal, including an MCU, a relay drive circuit, a magnetic field intensity detection circuit, and a relay anti-strong magnetic drive and hold circuit.

[0041] The MCU is connected to the relay coil through the relay drive circuit, and the relay drive circuit is used to output a basic drive current to the relay coil.

[0042] The output end of the magnetic field intensity detection circuit is connected to the MCU, and is used to detect the intensity of the interference magnetic field and send the magnetic field intensity detection signal to the MCU.

[0043] The MCU is connected to the relay coil through the relay anti-strong magnetic drive and hold circuit, and the relay anti-strong magnetic drive and hold circuit is used to output an auxiliary current to the relay coil.

[0044] Specifically:

[0045] As Figure 2 , the magnetic field intensity detection circuit is based on the MT6131 model chip, and the output end Vout of the chip is connected to the 36th pin of the MCU chip, and sends the magnetic field intensity detection signal CEKHALL to the MCU.

[0046] As Figure 3 , the MCU model is HT6025, it receives the magnetic field intensity detection signal CEKHALL, and outputs four control signals: RelayOn, RelayOff, RelayKeepOn, RelayKeepOff. Among them, the signal RelayOn and the signal RelayOff are sent to the relay drive circuit, and the signal RelayKeepOn and the signal RelayKeepOff are sent to the relay anti-strong magnetic drive and hold circuit.

[0047] As Figure 4, the relay driving circuit includes optocouplers E1, E2 and a driving chip D1. The input ends of optocoupler E1 and optocoupler E2 are both connected to the MCU, receiving signal RelayOn and signal RelayOff respectively. The output ends of optocoupler E1 and optocoupler E2 are respectively connected to the IN1 input pin and IN2 input pin of the driving chip D1, for controlling the direction of the output current between the OUT1 output pin and OUT2 output pin of the driving chip D1. The OUT1 output pin and OUT2 output pin of the driving chip D1 are respectively connected to both ends of the relay coil.

[0048] Specifically, the positive pole of the input end of optocoupler E1 is connected to the 3.3V power supply, the negative pole of the input end receives signal RelayOn through resistor R1, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R3 and R5, and the connection point between resistors R3 and R5 is connected to the IN1 input pin of the driving chip D1. The positive pole of the input end of optocoupler E2 is connected to the 3.3V power supply, the negative pole of the input end receives signal RelayOff through resistor R2, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R4 and R6, and the connection point between resistors R4 and R6 is connected to the IN2 input pin of the driving chip D1. The VCC pin of the driving chip D1 is connected to the 5V power supply for power supply, and a filter capacitor C1 is connected between this VCC pin and the ground terminal. The ISET pin of the driving chip D1 is grounded through a pull-down resistor R7, and the threshold value of the output current of the driving chip D1 can be set by adjusting the resistance value of the pull-down resistor R7. In this embodiment, the resistance value of resistor R7 is 100 kΩ, and the output current is limited to 2A.

[0049] The relay anti-strong magnetic driving and holding circuit is basically similar in structure to the relay driving circuit: as Figure 5 , the relay anti-strong magnetic driving and holding circuit includes optocouplers E3, E4 and a driving chip D2. The input ends of optocoupler E3 and optocoupler E4 are both connected to the MCU, receiving signal RelayKeepOn and signal RelayKeepOff respectively. The output ends of optocoupler E3 and optocoupler E4 are respectively connected to the IN1 input pin and IN2 input pin of the driving chip D2, for controlling the direction of the output current between the OUT1 output pin and OUT2 output pin of the driving chip D2. The OUT1 output pin and OUT2 output pin of the driving chip D2 are respectively connected to both ends of the relay coil.

[0050] Specifically, the positive pole of the input end of optocoupler E3 is connected to the 3.3V power supply, the negative pole of the input end receives the signal RelayKeepOn through resistor R8, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R10 and R12, and the connection point between resistors R10 and R12 is connected to the IN1 input pin of drive chip D2. The positive pole of the input end of optocoupler E4 is connected to the 3.3V power supply, the negative pole of the input end receives the signal RelayKeepOff through resistor R9, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R11 and R13, and the connection point between resistors R11 and R13 is connected to the IN2 input pin of drive chip D2. The VCC pin of drive chip D2 is connected to the 5V power supply for power supply, and a filter capacitor C3 is connected between this VCC pin and the ground terminal. The ISET pin of drive chip D2 is grounded through a pull-down resistor R14, and the threshold value of the output current of drive chip D1 can be set by adjusting the resistance value of pull-down resistor R14. In this embodiment, the resistance value of resistor R14 is 100 kΩ, and the output current is limited to 2A.

[0051] The difference between the relay anti-strong magnetic drive hold circuit and the relay drive circuit is that: a current-limiting resistor R20 is also connected between the OUT1 output pin and / or the OUT2 output pin of drive chip D2 and the relay coil, which is used to limit the magnitude of the auxiliary current output. In this embodiment, the resistance value of the current-limiting resistor R20 is a high-power resistor of about 50 Ω.

[0052] In this embodiment, the models of drive chips D1 and D2 are both 8251SEC.

[0053] Embodiment 2

[0054] This embodiment provides an anti-magnetic field interference method based on Embodiment 1: The magnetic field intensity detection circuit continuously detects the intensity of the interfering magnetic field and sends the magnetic field intensity detection signal to the MCU. The MCU determines whether it is currently in a strong magnetic field interference state according to the magnetic field intensity detection signal. Preferably, the MCU determines whether it is in a strong magnetic field interference state according to whether the magnetic field intensity detection signal exceeds a preset value.

[0055] If in a strong magnetic field interference state: When it is necessary to control the relay to operate, the MCU controls the relay drive circuit to output a basic drive current to the relay coil, and at the same time controls the relay anti-strong magnetic drive holding circuit to output an auxiliary current in the same direction as the drive current to the relay coil. The basic drive current and the auxiliary current pass through the relay coil at the same time, increasing the drive current when the relay operates. When it is necessary for the relay to maintain its original state, the MCU controls the relay anti-strong magnetic drive holding circuit to output an auxiliary current in the same direction as the drive current during the previous operation to the relay coil, and controls the relay drive circuit not to output the basic drive current.

[0056] If not in a strong magnetic field interference state: When it is necessary to control the relay to operate, the MCU controls the relay drive circuit to output a basic drive current to the relay coil, and the relay anti-strong magnetic drive holding circuit does not output current. When it is necessary for the relay to maintain its original state, neither the relay drive circuit nor the relay anti-strong magnetic drive holding circuit outputs current.

[0057] The specific control logic of the relay drive circuit is as follows:

[0058] When both the signal RelayOn and the signal RelayOff are at high level, the relay drive circuit does not output the basic current, and the relay maintains its original state.

[0059] When the signal RelayOn is at low level and the signal RelayOff is at high level, optocoupler E1 conducts and optocoupler E2 turns off. The 5V power supply pulls up the IN1 input pin of the drive chip D1 through resistors R3 and R5. At the same time, the IN2 input pin of the drive chip D1 is pulled down by resistor R6. The OUT1 output pin of the drive chip D1 is pulled up and the OUT2 output pin is set low. At this time, the output basic drive current flows from the OUT1 output pin to the OUT2 output pin, and the relay trips.

[0060] When the signal RelayOn is at high level and the signal RelayOff is at low level, optocoupler E1 turns off and optocoupler E2 conducts. The IN1 input pin of the drive chip D1 is pulled down by resistor R6. At the same time, the 5V power supply pulls up the IN2 input pin of the drive chip D1 through resistors R4 and R6. The OUT1 output pin of the drive chip D1 is set low and the OUT2 output pin is pulled up. At this time, the output basic drive current flows from the OUT2 output pin to the OUT1 output pin, and the relay closes.

[0061] The specific control logic of the relay anti-strong magnetic drive holding circuit is as follows:

[0062] When both the signal RelayKeepOn and the signal RelayKeepOff are at high level, the relay anti-strong magnetic drive holding circuit does not output the auxiliary current and does not affect the magnetic field of the relay coil.

[0063] When the signal RelayKeepOn is at a low level and the signal RelayKeepOff is at a high level, optocoupler E3 conducts and optocoupler E4 turns off. The 5V power supply pulls up the IN1 input pin of the driving chip D2 through resistors R10 and R12. At the same time, the IN2 input pin of the driving chip D2 is pulled low by resistor R13. The OUT1 output pin of the driving chip D2 is pulled high and the OUT2 output pin is set low. At this time, the output auxiliary current flows from the OUT1 output pin to the OUT2 output pin, and the auxiliary relay performs a tripping action or maintains the current tripping state.

[0064] When the signal RelayKeepOn is at a high level and the signal RelayKeepOff is at a low level, optocoupler E3 turns off and optocoupler E4 conducts. The IN1 input pin of the driving chip D2 is pulled low by resistor R13. At the same time, the 5V power supply pulls up the IN2 input pin of the driving chip D2 through resistors R11 and R13. The OUT1 output pin of the driving chip D2 is set low and the OUT2 output pin is pulled high. At this time, the output auxiliary current flows from the OUT2 output pin to the OUT1 output pin, and the auxiliary relay performs a closing action or maintains the current closing state.

[0065] It should be noted that for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. The scope of the present invention is defined by the claims rather than the above description.

Claims

1. A magnetic holding relay anti-magnetic field interference module for an electric energy meter and a terminal, comprising an MCU and a relay driving circuit. The MCU is connected to a relay coil through the relay driving circuit, and the relay driving circuit is used to output a basic driving current to the relay coil. It is characterized in that: The anti-magnetic field interference module further includes a magnetic field intensity detection circuit and a relay anti-strong magnetic driving and holding circuit; The output end of the magnetic field intensity detection circuit is connected to the MCU, and is used to detect the intensity of the interference magnetic field and send a magnetic field intensity detection signal to the MCU; The MCU is connected to the relay coil through the relay anti-strong magnetic driving and holding circuit, and the relay anti-strong magnetic driving and holding circuit is used to output an auxiliary current to the relay coil.

2. The magnetic holding relay anti-magnetic field interference module of the electric energy meter and the terminal according to claim 1, wherein: The relay driving circuit includes optocoupler E1, optocoupler E2 and driving chip D1; The input ends of optocoupler E1 and optocoupler E2 are both connected to the MCU, and receive signal RelayOn and signal RelayOff respectively; The output ends of optocoupler E1 and optocoupler E2 are respectively connected to the IN1 input pin and IN2 input pin of the driving chip D1, and are used to control the direction of the output current between the OUT1 output pin and OUT2 output pin of the driving chip D1; The OUT1 output pin and OUT2 output pin of the driving chip D1 are respectively connected to both ends of the relay coil.

3. The magnetic holding relay anti-magnetic field interference module of the electric energy meter and the terminal according to claim 2, characterized in that: The positive pole of the input end of optocoupler E1 is connected to the 3.3V power supply, the negative pole of the input end receives signal RelayOn through resistor R1, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R3 and R5, and the connection point between resistors R3 and R5 is connected to the IN1 input pin of the driving chip D1; The positive pole of the input end of optocoupler E2 is connected to the 3.3V power supply, the negative pole of the input end receives signal RelayOff through resistor R2, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through the series-connected resistors R4 and R6, and the connection point between resistors R4 and R6 is connected to the IN2 input pin of the driving chip D1.

4. The magnetic holding relay anti-magnetic field interference module of the electric energy meter and the terminal according to claim 3, characterized in that: The ISET pin of the driving chip D1 is grounded through a pull-down resistor R7, and the threshold value of the output current of the driving chip D1 can be set by adjusting the resistance value of the pull-down resistor R7.

5. The magnetic holding relay anti-magnetic field interference module of the electric energy meter and the terminal according to claim 1, characterized in that: The relay anti-strong magnetic driving and holding circuit includes optocoupler E3, optocoupler E4 and driving chip D2; The input ends of optocoupler E3 and optocoupler E4 are both connected to the MCU, and receive signal RelayKeepOn and signal RelayKeepOff respectively; The output ends of optocoupler E3 and optocoupler E4 are respectively connected to the IN1 input pin and IN2 input pin of the driving chip D2, and are used to control the direction of the output current between the OUT1 output pin and OUT2 output pin of the driving chip D2; The OUT1 output pin and OUT2 output pin of the driving chip D2 are respectively connected to both ends of the relay coil.

6. The magnetic holding relay anti-magnetic field interference module of the electric energy meter and the terminal according to claim 5, characterized in that: The positive terminal of the input end of optocoupler E3 is connected to the 3.3V power supply, the negative terminal of the input end receives the signal RelayKeepOn through resistor R8, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through series resistors R10 and R12, and the connection point between resistors R10 and R12 is connected to the IN1 input pin of driver chip D2; The positive terminal of the input end of optocoupler E4 is connected to the 3.3V power supply, the negative terminal of the input end receives the signal RelayKeepOff through resistor R9, the collector of the output end is connected to the 5V power supply, the emitter of the output end is grounded through series resistors R11 and R13, and the connection point between resistors R11 and R13 is connected to the IN2 input pin of driver chip D2.

7. The anti-magnetic field interference module of the magnetic latching relay of the electric energy meter and the terminal according to claim 6, characterized in that: The ISET pin of driver chip D2 is grounded through pull-down resistor R14, and the threshold value of the output current of driver chip D1 can be set by adjusting the resistance value of pull-down resistor R14.

8. The magnetic holding relay anti-magnetic field interference module of the electric energy meter and the terminal according to claim 5, characterized in that: A current-limiting resistor R20 is also connected between the OUT1 output pin and / or the OUT2 output pin of driver chip D2 and the relay coil, which is used to limit the magnitude of the output auxiliary current.

9. An anti-magnetic field interference method based on the anti-magnetic field interference module according to any one of claims 1 to 8, characterized in that: The magnetic field intensity detection circuit detects the intensity of the interfering magnetic field in real time and sends the magnetic field intensity detection signal to the MCU. The MCU determines whether it is in a strong magnetic field interference state according to the magnetic field intensity detection signal; If in a strong magnetic field interference state: when the relay needs to be controlled to act, the MCU controls the relay drive circuit to output a basic drive current to the relay coil and at the same time controls the relay anti-strong magnetic drive holding circuit to output an auxiliary current in the same direction as the drive current to the relay coil. The basic drive current and the auxiliary current pass through the relay coil at the same time to increase the drive current when the relay acts; when the relay needs to maintain its original state, the MCU controls the relay anti-strong magnetic drive holding circuit to output an auxiliary current in the same direction as the drive current during the previous action to the relay coil, and controls the relay drive circuit not to output the basic drive current.

10. The anti-magnetic field interference method according to claim 9, wherein If not in a strong magnetic field interference state: when the relay needs to be controlled to act, the MCU controls the relay drive circuit to output a basic drive current to the relay coil, and the relay anti-strong magnetic drive holding circuit does not output current; when the relay needs to maintain its original state, neither the relay drive circuit nor the relay anti-strong magnetic drive holding circuit outputs current.

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