Permanent magnet interference prevention method and circuit for intelligent electric energy meter and intelligent fusion terminal power supply

Abstract

The invention discloses a permanent magnet interference prevention method and circuit for an intelligent electric energy meter and an intelligent fusion terminal power supply, and the method comprises the steps that a single-chip microcomputer outputs a pulse width modulation (PWM) wave to drive a second MOS tube to be switched on or switched off, so that the PWM wave is inputted to a copper wire wound by a coil of a relay, the copper wire generates impedance under the PWM wave, and the impedance is transmitted to the second MOS tube; coil output of the relay is connected to the single-chip microcomputer for voltage acquisition after being subjected to voltage division by a fourth resistor; the external magnetic field magnetizes the soft iron in the coil of the relay, the magnetized soft iron and the wound copper wire form an inductance structure, that is, the soft iron is equivalent to a magnetic core of an inductor, the magnetic flux of the magnetic core is increased, and the impedance formed by the PWM wave passing through the coil of the relay is increased; detecting the voltage passing through the coil of the relay to determine the current magnetic field intensity; the single-chip microcomputer adjusts the PWM wave output to the first MOS tube according to the detected magnetic field intensity, and the frequency of the PWM wave is increased, so that the antimagnetic capability of the power supply is improved. According to the invention, the permanent magnet interference can be efficiently prevented under the requirements of low carbon and low cost.

Description

Technical Field

[0001] This application relates to the field of anti-interference technology, and in particular to a method and circuit for preventing permanent magnet interference in the power supply of a smart energy meter and a smart fusion terminal. Background Technology

[0002] With the widespread application of smart meters and smart converged terminals in low-voltage network smart meters, it is necessary to ensure the normal operation of the internal power supply of the meter when it is interfered with by a permanent magnet. Increasing the size of the meter cannot simply improve the distance between the internal power supply and the permanent magnet. Instead, efforts should be made to reduce the use of plastic materials, minimize the use of large-area metal shielding shells, and reduce the use of high-flux transformer cores within a smaller meter size. Summary of the Invention In view of this, this application provides a method and circuit for preventing permanent magnet interference in smart meters and smart converged terminal power supplies. When smart meters are subjected to permanent magnet interference, under the requirements of low carbon and low cost, the design of preventing permanent magnet interference in smart meters and smart converged terminal power supplies is mainly carried out through magnetic field strength detection, transformer core and frame design, and switching power supply operating frequency design.

[0003] This application discloses a method for preventing permanent magnet interference in the power supply of smart energy meters and smart converged terminals, which includes: The microcontroller outputs a PWM wave to drive the second MOSFET to turn on or off, so that the PWM wave is input to the copper wire wound around the relay coil. The copper wire generates impedance under the PWM wave. The relay coil output is connected to the microcontroller for voltage acquisition after being divided by the fourth resistor. An external magnetic field magnetizes the soft iron inside the relay coil. After magnetization, the soft iron forms an inductive structure with the wound copper wire, meaning the soft iron is equivalent to an inductor core. At this time, the magnetic flux of the core increases, increasing the impedance formed by the PWM wave passing through the relay coil. The voltage through the relay coil is detected to determine the current magnetic field strength. The microcontroller records the magnetic field event and its occurrence time. Simultaneously, based on the detected magnetic field strength, the microcontroller adjusts the PWM wave output to the first MOSFET, increasing the frequency of the PWM wave to enhance the power supply's anti-magnetic capability.

[0004] Furthermore, once the smart energy meter and smart fusion terminal are manufactured as a complete unit, the strength of the external magnetic field is determined by the magnetic flux of different external magnetic fields and the different ADC values ​​collected by the microcontroller.

[0005] Furthermore, when the smart meter and smart fusion terminal are powered on normally and there is no magnetic field interference, the AC rectifier and filter circuit rectifies and filters the external AC mains power into DC power. This DC power passes through the switching power supply transformer, enters the first MOSFET, and then returns to the AC rectifier and filter circuit. The microcontroller starts working from the high-voltage power supply circuit, and drives the first MOSFET to be on or off through the PWM wave, so that the switching power supply transformer is charging and discharging. The microcontroller collects the DC voltage output after rectification and filtering by the switching power supply transformer, and uses the switching power supply voltage feedback circuit to adjust the duty cycle of the PWM wave output to make the power supply output stable and serve as the input of the voltage conversion circuit. The voltage conversion circuit outputs the voltage to power the microcontroller.

[0006] Furthermore, the microcontroller is connected to the relay coil, which is composed of copper wire wound with soft iron. The relay coil acts as a relay opening and closing driver and is also used for magnetic field detection. The microcontroller outputs a PWM wave, which enters the copper wire through one end of the relay coil. The copper wire generates impedance, and the output of the other end of the relay coil is connected to the microcontroller through a resistor divider for voltage acquisition. An external magnetic field magnetizes the soft iron inside the relay coil. After magnetization, the wound copper core forms an inductor structure, meaning the soft iron is equivalent to an inductor core. At this time, the magnetic flux of the core increases, causing the impedance of the PWM wave passing through the relay coil to increase. The voltage passing through the relay coil is detected to determine the current magnetic field strength. The microcontroller records the magnetic field event and its occurrence time. At the same time, the microcontroller adjusts the PWM wave output to the first MOSFET based on the detected magnetic field strength, thereby increasing the power supply's anti-magnetic capability.

[0007] Furthermore, the magnetic core of the switching power supply transformer is placed vertically and soldered to the back of the PCB board, with the top of the transformer facing the bottom shell and the bottom facing the top shell. The only side affected by interference is the top shell, i.e., the bottom of the transformer. It is only necessary to add an iron plate under the switching power supply transformer to conduct away the large number of magnetic field lines generated by the permanent magnet. This allows a large number of magnetic field lines to pass through the iron plate instead of through the magnetic core of the switching power supply transformer, thereby reducing magnetic core saturation and preventing the magnetic core from charging and discharging energy during the switching power supply process.

[0008] This application also discloses a circuit for preventing permanent magnet interference in the power supply of a smart energy meter and a smart fusion terminal, which is applicable to the aforementioned method for preventing permanent magnet interference in the power supply of a smart energy meter and a smart fusion terminal. It includes an AC rectifier and filter circuit, a high-voltage power supply circuit, a first MOSFET, a switching power supply transformer, a microcontroller, a relay coil, a voltage conversion circuit, a switching power supply voltage feedback circuit, and a relay.

[0009] Furthermore, the AC rectifier and filter circuit includes a first rectifier diode and a first capacitor connected in series between the live wire and the neutral wire; The high-voltage power extraction circuit includes a third resistor and a sixth Zener diode connected in series. The voltage divider circuit includes a fourth resistor, a fifth rectifier diode, and a third capacitor; The voltage feedback circuit of the switching power supply includes a first resistor and a second resistor connected in series.

[0010] Furthermore, it also includes a second rectifier diode, a third rectifier diode, a fourth rectifier diode, a seventh rectifier diode, a second MOSFET, and a second capacitor.

[0011] Furthermore, one end of the first capacitor is grounded via the third resistor and the sixth Zener diode, and the other end is connected to the source of the first MOSFET; the drain of the first MOSFET is connected to one terminal of the input of the switching power supply transformer; the other terminal of the input of the switching power supply transformer is connected to the cathode of the first rectifier diode; one end of the output of the switching power supply transformer is connected to the voltage conversion circuit via the second rectifier diode, and the other end is connected to the voltage conversion circuit via the second capacitor; the voltage conversion circuit is connected to the power supply terminal of the microcontroller via the third rectifier diode; the power supply terminal of the microcontroller is connected to the common terminal of the third resistor and the sixth Zener diode via the fourth rectifier diode; the microcontroller... The first control terminal is connected to the gate of the first MOSFET; the second control terminal of the microcontroller is connected to the gate of the second MOSFET; the source of the second MOSFET is grounded, and the drain is connected to one end of the relay coil; the DC power supply VCC is connected to one end of the relay coil through the seventh rectifier diode; the other end of the relay coil is grounded through the fourth resistor, and the other end is grounded through the fifth rectifier diode and the third capacitor in sequence; the common terminal of the fifth rectifier diode and the third capacitor is connected to the sampling terminal of the microcontroller; the third control terminal of the microcontroller is connected to the common terminal of the first resistor and the second resistor; the first resistor is connected to the common terminal of the second rectifier diode and the second capacitor, and one end of the second resistor is grounded.

[0012] Furthermore, the relay coil, microcontroller, and voltage divider circuit form a permanent magnet interference detection circuit to detect the external magnetic field strength; the microcontroller and the first MOSFET are used to adjust the operating frequency of the PWM wave driving the first MOSFET according to the detected external magnetic field strength.

[0013] Due to the adoption of the above technical solution, this application has the following advantages: This application can effectively prevent permanent magnet interference under the requirements of low carbon and low cost. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0015] Figure 1 This is a schematic diagram of a power supply anti-permanent magnet interference circuit for a smart energy meter and a smart fusion terminal according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a switching power supply transformer according to an embodiment of this application; Figure 3(a) is a schematic diagram of the structure of another switching power supply transformer according to an embodiment of this application; Figure 3(b) is a schematic diagram of another switching power supply transformer according to an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a relay according to an embodiment of this application; Figure 5 This is a schematic diagram illustrating the relationship between the frequency of the PWM wave and the impedance of the copper wire in the absence of interference from a permanent magnet, according to an embodiment of this application. Figure 6 This is a schematic diagram showing the relationship between the frequency of the PWM wave and the impedance of the copper wire when a permanent magnet interference is applied in an embodiment of this application. Detailed Implementation

[0016] The present application will be further described in conjunction with the accompanying drawings and embodiments. The described embodiments are only some, not all, of the embodiments of the present application. All other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of the present application.

[0017] See Figure 1 This application provides an embodiment of a method for preventing permanent magnet interference in the power supply of a smart energy meter and a smart converged terminal, which includes: The microcontroller A5 outputs a pulse width modulation (PWM) wave to drive the second MOSFET Q2 to turn on or off, so that the PWM wave is input to the copper wire wound around the relay coil A6. The copper wire generates impedance under the PWM wave. The output of the relay coil A6 is connected to the microcontroller A5 for voltage acquisition after being divided by the fourth resistor R4. An external magnetic field magnetizes the soft iron inside the relay coil A6. After magnetization, the soft iron forms an inductive structure with the wound copper wire, meaning the soft iron is equivalent to an inductor core. At this time, the magnetic flux of the core increases, increasing the impedance formed by the PWM wave passing through the relay coil A6. The voltage through the relay coil A6 is detected to determine the current magnetic field strength. The microcontroller A5 records the magnetic field event and its occurrence time. Simultaneously, based on the detected magnetic field strength, the microcontroller A5 adjusts the PWM wave output to the first MOSFET Q1, increasing the frequency of the PWM wave to enhance the power supply's anti-magnetic capability.

[0018] Optionally, after the smart energy meter and smart fusion terminal are manufactured into a complete unit, the strength of the external magnetic field is determined by the magnetic flux of different external magnetic fields and the different ADC values ​​collected by the microcontroller A5.

[0019] Optionally, when the smart meter and smart fusion terminal are powered on normally and there is no magnetic field interference, the AC rectifier and filter circuit A1 rectifies and filters the external AC mains power into DC power. This DC power passes through the switching power supply transformer A4 and enters the first MOSFET Q1 before returning to the AC rectifier and filter circuit A1. The microcontroller A5 starts working, powered by the high-voltage power supply circuit A2. It drives the first MOSFET Q1 to be on or off via a PWM wave, causing the switching power supply transformer A4 to charge and discharge. The microcontroller A5 collects the DC voltage output after rectification and filtering by the switching power supply transformer A4, and uses the switching power supply voltage feedback circuit A9 to adjust the duty cycle of the PWM wave output to stabilize the power supply output and use it as the input of the voltage conversion circuit LDO. The voltage conversion circuit LDO (corresponding to Figure 1 The output voltage of A8 in the microcontroller powers A5 of the microcontroller.

[0020] Optionally, the microcontroller A5 is connected to the relay coil A6. The relay coil A6 is composed of copper wire wound with soft iron material. The relay coil A6 serves as a relay opening and closing driver and is also used for magnetic field detection. The microcontroller A5 outputs a PWM wave, which enters the copper wire through one end of the relay coil A6. The copper wire generates impedance, and the output of the other end of the relay coil A6 is connected to the microcontroller A5 through a resistor divider for voltage acquisition. An external magnetic field will magnetize the soft iron inside the relay coil A6. After the soft iron is magnetized, the wound copper core forms an inductor structure, that is, the soft iron is equivalent to an inductor core. At this time, the magnetic flux of the core increases, which increases the impedance of the PWM wave passing through the relay coil A6. The voltage passing through the relay coil A6 is detected to determine the current magnetic field strength. The microcontroller A5 records the magnetic field event and the occurrence time. At the same time, the microcontroller A5 adjusts the PWM wave output to the first MOSFET Q1 according to the detected magnetic field strength, thereby increasing the anti-magnetic capability of the power supply.

[0021] Optionally, the magnetic core of the switching power supply transformer A4 is placed vertically and soldered to the back of the PCB board, with the top of the transformer A4 facing the bottom shell and the bottom facing the top shell. The only side affected by interference is the top shell, i.e., the bottom of the transformer. It is only necessary to add an iron plate under the transformer A4 to block the large number of magnetic field lines generated by the permanent magnet, so that a large number of magnetic field lines pass through the iron plate instead of the magnetic core of the transformer A4, thereby reducing the saturation of the magnetic core and preventing the magnetic core from charging and discharging energy during the switching power supply process.

[0022] This application also discloses a circuit for preventing permanent magnet interference in the power supply of a smart energy meter and a smart converged terminal, applicable to the aforementioned method for preventing permanent magnet interference in the power supply of a smart energy meter and a smart converged terminal. It includes an AC rectifier and filter circuit A1, a microcontroller A5, a high-voltage power supply circuit A2, and a first MOSFET Q1 (corresponding to...). Figure 1 The components include A3, A4 (switching power supply transformer), A6 (relay coil), A7 (voltage divider circuit), LDO (voltage conversion circuit), A9 (switching power supply voltage feedback circuit), and the relay.

[0023] Optionally, the AC rectifier and filter circuit A1 includes a first rectifier diode D1 and a first capacitor C1 connected in series between the live wire L and the neutral wire N; the neutral wire N is grounded; The high-voltage power supply circuit A2 includes a third resistor R3 and a sixth Zener diode D6 connected in series. Voltage divider circuit A7 includes a fourth resistor R4, a fifth rectifier diode D5, and a third capacitor C3; The switching power supply voltage feedback circuit A9 includes a first resistor R1 and a second resistor R2 connected in series.

[0024] Optionally, it also includes a second rectifier diode D2, a third rectifier diode D3, a fourth rectifier diode D4, a seventh rectifier diode D7, a second MOSFET Q2, and a second capacitor C2.

[0025] Optionally, one end of the first capacitor C1 is grounded through the third resistor R3 and the sixth Zener diode D6, and the other end is connected to the source of the first MOSFET Q1; the drain of the first MOSFET Q1 is connected to one terminal of the input of the switching power supply transformer A4; the other terminal of the input of the switching power supply transformer A4 is connected to the cathode of the first rectifier diode D1; one end of the output of the switching power supply transformer A4 is connected to the voltage conversion circuit LDO through the second rectifier diode D2, and the other end is connected to the voltage conversion circuit LDO through the second capacitor C2; the voltage conversion circuit LDO is connected to the power supply terminal of the microcontroller A5 through the third rectifier diode D3; the power supply terminal of the microcontroller A5 is connected to the common terminal of the third resistor R3 and the sixth Zener diode D6 through the fourth rectifier diode D4; the microcontroller A... The first control terminal of microcontroller A5 is connected to the gate of the first MOSFET Q1; the second control terminal of microcontroller A5 is connected to the gate of the second MOSFET Q2; the source of the second MOSFET Q2 is grounded, and the drain is connected to one end of the relay coil A6; the DC power supply VCC is connected to one end of the relay coil A6 through the seventh rectifier diode D7; the other end of the relay coil A6 is grounded through the fourth resistor R4, and the other end is grounded through the fifth rectifier diode D5 and the third capacitor C3 in sequence; the common terminal of the fifth rectifier diode D5 and the third capacitor C3 is connected to the sampling terminal of microcontroller A5; the third control terminal of microcontroller A5 is connected to the common terminal of the first resistor R1 and the second resistor R2; the first resistor R1 is connected to the common terminal of the second rectifier diode D2 and the second capacitor C2, and one end of the second resistor R2 is grounded.

[0026] Optionally, the relay coil A6, the microcontroller A5, and the voltage divider circuit A7 form a permanent magnet interference detection circuit to detect the external magnetic field strength; the microcontroller A5 and the first MOSFET Q1 are used to adjust the operating frequency of the PWM wave drive A3 according to the detected external magnetic field strength.

[0027] Based on the above embodiment, when powered on normally and without magnetic field interference, A1 rectifies and filters the AC power into DC power. A1 receives AC mains power as input and outputs DC power. The DC output of A1 is connected to A4, and the output of A4 is connected to Q1. The microcontroller A5 is powered by the high-voltage power supply circuit A2 and starts working. It drives A3 to be on and off with a default 45kHz PWM wave with a 20% duty cycle, causing the switching power supply transformer A4 to charge and discharge, outputting 12V power. The microcontroller collects the 12V voltage and uses voltage feedback A9 to adjust the duty cycle of the PWM wave output. At this time, the 12V power supply is stably output. The 12V is used as the input of LDOA8, and A8 outputs 5V power to power the microcontroller A5.

[0028] The microcontroller A5 is connected to the relay coil A6. A6 is originally used for relay opening and closing control. The relay coil is made of copper wire wound with soft iron material. Here, the relay coil not only acts as the relay opening and closing driver, but also as a magnetic field detector. The microcontroller A5 outputs a 300KHz PWM wave with a duty cycle of 50%. The copper wire wound inside the relay coil generates impedance at 300KHz. The output of the other end of the relay coil is connected to the microcontroller A5 through a resistor divider for voltage acquisition.

[0029] The switching power supply transformer A4 uses an EE-shaped magnetic core. Typically, to allow for a large number of copper wire turns on the transformer, the magnetic core is placed horizontally, such as... Figure 2 As shown, the locations of the left and right sides of the transformer are indicated. A horizontal magnetic core is positioned between the left and right sides of the transformer. The vertical space of the switching power supply transformer is unrestricted, allowing for numerous turns of copper wire. However, a drawback is that the NS (new and neutral) terminals of the magnetic core are also horizontal. After the transformer is soldered onto the PCB, the magnetic core and PCB are horizontal, and the PCB is parallel to the front and back of the meter. The left and right sides of the transformer are susceptible to interference from permanent magnets. When this occurs, the NS terminals of the transformer core are repelled by the permanent magnets, or the magnetic flux through the transformer is much greater than the core's own magnetic flux, leading to core saturation. Once the core is saturated, the transformer cannot function as a storage medium in the switching power supply, thus failing to complete the switching power supply operation and causing abnormal power supply operation. When using this horizontal magnetic core structure, if it is necessary to resist permanent magnet interference, and the smart meter and smart fusion terminal power supply can operate normally in the presence of permanent magnets, the distance between the transformer and the permanent magnet needs to be increased, which increases the product size. Alternatively, a shielding iron shell can be added to enclose the transformer, which increases the amount of metal used and affects the transformer's own magnetic flux, reducing its efficiency. None of them conform to the green and low-carbon design concept.

[0030] When designing smart meters and smart converged terminals, the IEC 62052-11 standard is referenced, specifying that surfaces that the product may come into contact with must withstand 50... 50 Interference from a 25mm, 0.4T permanent magnet. Exemption is given if there are inaccessible surfaces after installation. Based on this, the transformer can be modified from a horizontal to a vertical structure, as shown in Figures 3(a) and 3(b). The NS-grade core is vertical, and the surfaces susceptible to permanent magnet interference are the top and bottom of the transformer. The transformer is soldered to the back of the PCB board, with the top facing the bottom shell and the bottom facing the top shell. The only surface affected by interference is the bottom shell of the transformer. This requires only adding a 1mm iron plate below the transformer. Utilizing the principle that the iron plate can conduct away a large number of magnetic field lines, the permanent magnet's magnetic field lines pass through the iron plate instead of through the transformer core, reducing core saturation and preventing the core from charging and discharging energy during the switching power supply process. In Figures 3(a) and 3(b), the switching power supply transformer includes a vertical core and an iron plate, and the locations of the top and bottom of the transformer are shown.

[0031] The structure of a relay is as follows Figure 4 As shown, it includes a relay closing contact, a closing contact, a coil interface, copper wire for inner loop crosstalk, and a soft iron core.

[0032] The microcontroller A5 has a PWM output pin connected to the second MOSFET Q2. This pin outputs a 300kHz PWM wave with a 50% duty cycle, turning on the second MOSFET Q2. The output of Q2 connects to the first interface of the relay coil. The PWM signal is input to the copper wire wound inside the relay coil. The copper wire generates impedance under the 300kHz signal. The output of the relay coil's second interface is connected to the microcontroller via a resistor divider for voltage acquisition. An external magnetic field magnetizes the soft iron inside A6. This magnetization, combined with the wound copper wire, forms an inductive structure, effectively making the soft iron an equivalent inductor core. This increases the magnetic flux of the core, increasing the impedance of the 300kHz PWM wave passing through the relay coil. The current magnetic field strength can be determined by detecting the voltage across the relay coil.

[0033] A PWM wave of 50~500KHz is generated by a microcontroller A5. The value of the ADC is measured and converted into the impedance of the copper wire wound inside the relay control coil. Figure 5 Without applying permanent magnet interference, it can be seen that after a 300kHz PWM wave is input to the relay control coil, its copper wire impedance is approximately 20KΩ. For example... Figure 6This is the case with permanent magnet interference. It can be seen that after a 300kHz PWM wave is input to the relay control coil, its copper wire impedance is approximately 47KΩ. When a 300kHz PWM wave with a 50% duty cycle and a peak value of 5V is input to the relay control coil, the coil outputs a PWM wave that is divided by resistor R4 (20KΩ). Without permanent magnet interference, the PWM waveform across R4 is a 300kHz waveform with a 50% duty cycle and a peak-to-peak value of 2.5V, formed by the 20KΩ relay control coil impedance and resistor R4. After passing through the fifth rectifier diode D5 and the filter energy storage capacitor (third capacitor) C3, the PWM waveform across R4 is rectified and filtered into a DC voltage, which is then fed to the ADC pin of the microcontroller A5 for voltage sampling.

[0034] When there is permanent magnet interference, the PWM waveform across R4 is a voltage divider formed by the relay control coil impedance of 47KΩ and R4. The PWM waveform across R4 is 300KHz, with a duty cycle of 50% and a peak-to-peak value of 1.5V. After passing through rectifier diode D5 and filter energy storage capacitor C3, the PWM waveform across R4 is rectified and filtered into a DC voltage, which is then supplied to the ADC pin of microcontroller A5 for voltage sampling. Because the input voltage to the ADC is different, the ADC can distinguish whether there is permanent magnet interference.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A method for preventing permanent magnet interference in the power supply of a smart energy meter and a smart integrated terminal, characterized in that, include: The microcontroller outputs a pulse width modulation (PWM) wave to drive the second MOSFET to turn on or off, so that the PWM wave is input to the copper wire wound around the relay coil. The copper wire generates impedance under the PWM wave, and the relay coil output is connected to the microcontroller for voltage acquisition after being divided by the fourth resistor. An external magnetic field magnetizes the soft iron inside the relay coil. After magnetization, the soft iron forms an inductive structure with the wound copper wire, meaning the soft iron is equivalent to an inductor core. At this time, the magnetic flux of the core increases, increasing the impedance formed by the PWM wave passing through the relay coil. The voltage through the relay coil is detected to determine the current magnetic field strength. The microcontroller records the magnetic field event and its occurrence time. Simultaneously, based on the detected magnetic field strength, the microcontroller adjusts the PWM wave output to the first MOSFET, increasing the frequency of the PWM wave to enhance the power supply's anti-magnetic capability.

2. The method for preventing permanent magnet interference in the power supply of smart energy meters and smart integrated terminals according to claim 1, characterized in that, Once the smart energy meter and smart fusion terminal are manufactured as a complete unit, the strength of the external magnetic field is determined by the magnetic flux of different external magnetic fields and the different ADC values ​​collected by the microcontroller.

3. The method for preventing permanent magnet interference in smart energy meters and smart converged terminal power supplies according to claim 1, characterized in that, When the smart meter and smart fusion terminal are powered on normally and there is no magnetic field interference, the AC rectifier and filter circuit rectifies and filters the external AC mains power into DC power. This DC power passes through the switching power supply transformer, enters the first MOSFET, and then returns to the AC rectifier and filter circuit. The microcontroller starts working with power from the high-voltage power supply circuit. It drives the first MOSFET to be on or off through a PWM wave, so that the switching power supply transformer is charging and discharging. The microcontroller collects the DC voltage output after rectification and filtering by the switching power supply transformer, and uses the switching power supply voltage feedback circuit to adjust the duty cycle of the PWM wave output to stabilize the power output and use it as the input of the voltage conversion circuit. The voltage conversion circuit outputs the voltage to power the microcontroller.

4. The method for preventing permanent magnet interference in the power supply of a smart energy meter and a smart converged terminal according to claim 1, characterized in that, The microcontroller connects to the relay coil, which is composed of copper wire wound with soft iron. The relay coil acts as a relay opening and closing driver and is also used for magnetic field detection. The microcontroller outputs a PWM wave, which passes through one end of the relay coil and enters the copper wire, creating impedance. The output from the other end of the relay coil is connected to the microcontroller via a resistor divider for voltage acquisition. An external magnetic field magnetizes the soft iron inside the relay coil. After magnetization, the wound copper core forms an inductor structure, meaning the soft iron is equivalent to an inductor core. This increases the magnetic flux of the core, increasing the impedance of the PWM wave passing through the relay coil. The voltage across the relay coil is detected to determine the current magnetic field strength. The microcontroller records the magnetic field event and its occurrence time. Simultaneously, based on the detected magnetic field strength, the microcontroller adjusts the PWM wave output to the first MOSFET, thereby increasing the power supply's anti-magnetic capability.

5. The method for preventing permanent magnet interference in smart energy meters and smart converged terminal power supplies according to claim 1, characterized in that, The core of the switching power supply transformer is placed vertically and soldered to the back of the PCB board, with the top of the transformer facing the bottom shell and the bottom facing the top shell. The only side affected by interference is the bottom shell of the transformer. Simply add an iron plate under the switching power supply transformer to block the large number of magnetic field lines generated by the permanent magnet. This will cause a large number of magnetic field lines to pass through the iron plate instead of the core of the switching power supply transformer, thereby reducing core saturation and preventing the core from charging and discharging energy during the switching power supply process.

6. A circuit for preventing permanent magnet interference in the power supply of a smart energy meter and a smart converged terminal, applicable to the method for preventing permanent magnet interference in the power supply of a smart energy meter and a smart converged terminal as described in any one of claims 1-5, characterized in that, It includes an AC rectifier and filter circuit, a high-voltage power supply circuit, a first MOSFET, a switching power supply transformer, a microcontroller, a relay coil, a voltage conversion circuit, a switching power supply voltage feedback circuit, and a relay.

7. The anti-permanent magnet interference circuit for smart energy meters and smart integrated terminal power supplies according to claim 6, characterized in that, The AC rectifier and filter circuit includes a first rectifier diode and a first capacitor connected in series between the live wire and the neutral wire; The high-voltage power extraction circuit includes a third resistor and a sixth Zener diode connected in series. The voltage divider circuit includes a fourth resistor, a fifth rectifier diode, and a third capacitor; The voltage feedback circuit of the switching power supply includes a first resistor and a second resistor connected in series.

8. The anti-permanent magnet interference circuit for smart energy meters and smart fusion terminal power supplies according to claim 7, characterized in that, It also includes a second rectifier diode, a third rectifier diode, a fourth rectifier diode, a seventh rectifier diode, a second MOSFET, and a second capacitor.

9. The anti-permanent magnet interference circuit for smart energy meters and smart fusion terminal power supplies according to claim 8, characterized in that, One end of the first capacitor is grounded via the third resistor and the sixth Zener diode, and the other end is connected to the source of the first MOSFET. The drain of the first MOSFET is connected to one terminal of the input of the switching power supply transformer. The other terminal of the input of the switching power supply transformer is connected to the cathode of the first rectifier diode. One end of the output of the switching power supply transformer is connected to the voltage conversion circuit via the second rectifier diode, and the other end is connected to the voltage conversion circuit via the second capacitor. The voltage conversion circuit is connected to the power supply terminal of the microcontroller via the third rectifier diode. The power supply terminal of the microcontroller is connected to the common terminal of the third resistor and the sixth Zener diode via the fourth rectifier diode. The first... The control terminal is connected to the gate of the first MOSFET; the second control terminal of the microcontroller is connected to the gate of the second MOSFET; the source of the second MOSFET is grounded, and the drain is connected to one end of the relay coil; the DC power supply VCC is connected to one end of the relay coil through the seventh rectifier diode; the other end of the relay coil is grounded through the fourth resistor, and the other end is grounded through the fifth rectifier diode and the third capacitor in sequence; the common terminal of the fifth rectifier diode and the third capacitor is connected to the sampling terminal of the microcontroller; the third control terminal of the microcontroller is connected to the common terminal of the first resistor and the second resistor; the first resistor is connected to the common terminal of the second rectifier diode and the second capacitor, and one end of the second resistor is grounded.

10. The anti-permanent magnet interference circuit for the smart energy meter and smart fusion terminal power supply according to claim 9, characterized in that, The relay coil, microcontroller, and voltage divider circuit form a permanent magnet interference detection circuit, used to detect the external magnetic field strength; the microcontroller and the first MOSFET are used to adjust the operating frequency of the PWM wave driving the first MOSFET according to the detected external magnetic field strength.

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