Multi-domain isolation power supply module of electric energy meter

Abstract

The utility model discloses a multi-domain isolation power supply module of an electric energy meter. The multi-domain isolation power supply module comprises a power frequency isolation multi-winding transformer; the input protection structure is arranged on the primary side of the power frequency isolation multi-winding transformer; the main power supply channel is connected with a first group of secondary windings of the power frequency isolation multi-winding transformer; the communication domain power supply channel is connected with a second group of secondary windings of the power frequency isolation multi-winding transformer; the digital domain power supply channel is connected with a third group of secondary windings of the power frequency isolation multi-winding transformer; and the standby power structure is arranged in the main power supply channel. The multi-domain isolation power supply module of the electric energy meter has the characteristics of good isolation, strong anti-interference capability, reliable power-off protection and compact structure.

Description

Technical Field

[0001] The utility model relates to a multi-domain isolation power supply module for an electric energy meter. Background Art

[0002] In modern electronic devices, especially energy meters, the reliability, anti-interference capabilities, and power supply stability of power supply circuits are crucial to the proper operation of the system. As device functionality becomes increasingly complex, multiple functional modules, such as digital processing, communication transmission, and data storage, are often integrated within the same device. These different functional modules have varying power quality requirements and are prone to interference with each other.

[0003] Traditional power supply circuits typically use a single transformer and a single power supply channel to power the entire system. This simple structure has significant drawbacks: High-frequency switching noise from digital circuits can easily couple to communication circuits through shared power lines, degrading communication quality. Furthermore, transient load changes in communication circuits can adversely affect control circuits. Furthermore, grid quality fluctuations and temporary power outages are major factors affecting system reliability, and traditional power supply structures lack effective protection against grid anomalies and power outages.

[0004] Common solutions currently available on the market involve adding multiple independent transformers and isolation modules, or employing dedicated uninterruptible power supplies and switching control chips. However, these solutions not only increase system size and cost, but also introduce additional control complexity. Therefore, a compact, low-cost, multi-domain isolated power supply module for energy meters with excellent anti-interference and power-off protection is needed. Utility Model Content

[0005] The utility model aims to provide a multi-domain isolated power supply module for an electric energy meter, which has the characteristics of good isolation, strong anti-interference capability, reliable power failure protection and compact structure.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A multi-domain isolated power supply module for an electric energy meter comprises: an industrial frequency isolated multi-winding transformer (T1) having a primary winding and at least three groups of secondary windings; an input protection structure arranged on the primary side of the industrial frequency isolated multi-winding transformer (T1), comprising a self-recovery fuse (PT1) connected in series to a mains N line and a varistor (RR1) connected across the AC side; a main power supply channel connected to the first group of secondary windings of the industrial frequency isolated multi-winding transformer (T1), comprising a rectifier bridge (D3), a filter capacitor group (C45, C46, ​​C53) and a linear regulator (U8), wherein the output end of the linear regulator (U8) is connected to an electrolytic capacitor (C48) and a ceramic capacitor (C1); a communication domain power supply channel connected to the second group of secondary windings of the industrial frequency isolated multi-winding transformer (T1), comprising a rectifier diode (D9), a filter capacitor (C46, C53) and a linear regulator (U8); 47, C44) and a linear voltage regulator (U9), the output end of the linear voltage regulator (U9) is connected to an electrolytic capacitor (C20) and a ceramic capacitor (C51); a digital domain power supply channel connected to the third group of secondary windings of the power frequency isolation multi-winding transformer (T1), including a rectifier diode (D19), a filter capacitor (C55, C25) and a linear voltage regulator (U7), the output end of the linear voltage regulator (U7) is connected to a ceramic capacitor (C54); a backup power structure arranged in the main power supply channel, including a dual diode (D10), a current limiting resistor (R10) and a super capacitor (C49), the first input end of the dual diode (D10) is connected to the output end of the linear voltage regulator (U8), and the second input end is connected to an external interface (J1) and the super capacitor (C49) through the current limiting resistor (R10).

[0008] The present invention is further configured as follows: the three groups of secondary windings respectively have independent reference grounds, including a main power channel ground, a communication domain ground (G485) and a digital domain ground, and the reference grounds are electrically isolated from each other.

[0009] The utility model is further configured such that: the output end of the linear voltage regulator (U8) of the main power supply channel is connected to a clamping protection diode (D1) for preventing output overvoltage from damaging the supercapacitor (C49).

[0010] The utility model is further configured as follows: the dual diodes (D10) are BAV23S type diodes, forming an "OR" structure to achieve automatic seamless switching between the main power supply and the backup power supply.

[0011] The utility model is further configured as follows: the super capacitor (C49) has a capacitance of 1.5F and a rated voltage of 5.5V, and is used to discharge to the VDD terminal through the dual diode (D10) to maintain system operation when the main power supply is cut off.

[0012] The present invention is further configured such that the rectification and voltage stabilization components corresponding to the three groups of secondary windings are physically isolated from each other to form a star topology structure.

[0013] The utility model is further configured as follows: the self-resetting fuse (PT1) is of FPTC type, which has the characteristics of automatically increasing resistance when overcurrent occurs and automatically recovering after the abnormality is eliminated.

[0014] The utility model is further configured as follows: the varistor (RR1) is labeled 20K / 681, corresponding to a clamping voltage of 680V.

[0015] In summary, the present invention has the following beneficial effects:

[0016] Multi-domain isolated power supply architecture: A single multi-winding power-frequency isolation transformer provides isolated power to three independent functional domains. This not only reduces noise coupling and interference between domains, improving system stability, but also offers a more compact and energy-efficient design compared to solutions using multiple independent power-frequency isolation transformers. The three secondary windings of the power-frequency isolation transformer are physically separated for electrical isolation and each connected to an independent reference ground, effectively suppressing ground loop interference.

[0017] Seamless Backup Power Switching: A dual-diode and supercapacitor backup power structure enables seamless automatic switching between primary and backup power without requiring additional control circuitry. When the primary power source is functioning properly, the dual diodes conduct to charge the supercapacitor. When the primary power source fails, the supercapacitor discharges into the system through the dual diodes, maintaining critical circuitry. This simple and reliable structure offers fast response and avoids instantaneous power outages during power switching.

[0018] Enhanced Input Protection: The primary-side input protection structure utilizes a combination of a resettable fuse and a varistor, forming a two-level protection barrier. The resettable fuse increases resistance to limit current in the event of overcurrent and automatically resets when the anomaly is resolved. The varistor quickly clamps the voltage during lightning strikes or surges, absorbing spike energy. This structure enhances the system's survivability in harsh power grid environments and extends the device's service life.

[0019] Optimized filtering and decoupling structure: Each power supply channel uses a multi-stage decoupling structure with large and small capacitors in parallel. Electrolytic capacitors provide high-capacity low-frequency filtering, while ceramic capacitors provide high-frequency decoupling. The combination of the two forms a broadband filtering network. This structure effectively suppresses various types of noise and interference, improves power quality, and ensures stable system operation.

[0020] Star topology layout optimization: Three sets of independent power channels radiate outward from the power frequency isolation multi-winding transformer to form a star topology structure. This not only reduces the mutual interference between the channels, but also minimizes the rectification loop area, reduces electromagnetic radiation, and improves electromagnetic compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a circuit diagram of the utility model.

[0022] Reference numerals:

[0023] 1. Power frequency isolation multi-winding transformer (T1); 2. Resettable fuse (PT1); 3. Varistor (RR1); 4. Rectifier bridge (D3); 5. Filter capacitor group (C45, C46, ​​C53); 6. Linear regulator (U8); 7. Electrolytic capacitor (C48); 8. Ceramic capacitor (C1); 9. Rectifier diode (D9); 10. Filter capacitor (C47, C44); 11. Linear regulator (U9); 12. Electrolytic capacitor Capacitor (C20); 13. Ceramic capacitor (C51); 14. Rectifier diode (D19); 15. Filter capacitor (C55, C25); 16. Linear regulator (U7); 17. Ceramic capacitor (C54); 18. Dual diode (D10); 19. Current-limiting resistor (R10); 20. Supercapacitor (C49); 21. External interface (J1); 22. Clamping protection diode (D1); 23. Communication domain ground (G485). DETAILED DESCRIPTION

[0024] The present invention will be described in further detail below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, the utility model provides a multi-domain isolated power supply module for an electric energy meter, which adopts a domain power supply structure and provides isolated power for three independent functional domains through an industrial frequency isolated multi-winding transformer (T1) 1.

[0026] The core component of this power supply circuit is the power frequency isolation multi-winding transformer (T1) 1, which has a primary winding and at least three sets of secondary windings. The primary winding of the power frequency isolation multi-winding transformer (T1) 1 is connected to the mains L / N line, with a self-resetting fuse (PT1) 2 connected in series on the N line. The self-resetting fuse (PT1) 2 is an FPTC type, which has the characteristics of automatically increasing resistance when overcurrent occurs and automatically recovering after the abnormality is eliminated, without the need for manual replacement. The primary side of the power frequency isolation multi-winding transformer (T1) 1 is also connected across a varistor (RR1) 3, labeled 20K / 681, corresponding to a clamping voltage of 680V, ​​which is used to absorb overvoltage spike energy generated by lightning strikes or grid surges.

[0027] The first secondary winding of the power-frequency isolation multi-winding transformer (T1) 1 is connected to the main power supply channel, which includes a rectifier bridge (D3) 4, a filter capacitor bank (C45, C46, ​​C53) 5, and a linear regulator (U8) 6. The rectifier bridge (D3) 4 converts AC power to DC power. The filter capacitor bank (C45, C46, ​​C53) 5, consisting of a large-capacity electrolytic capacitor C45 (1000μF / 25V) and small-capacity ceramic capacitors C46 and C53 (0.1μF each) in parallel, is used to filter out ripple after rectification. The linear regulator (U8) 6 is a 78L05 / MD8557. Its output is connected to an electrolytic capacitor (C48) 7 (470μF / 10V) and a ceramic capacitor (C1) 8 (0.1μF), respectively, to withstand load steps and improve high-frequency stability. The output end of the linear regulator (U8) 6 is also connected to a clamping protection diode (D1) 22 to prevent output overvoltage from damaging the subsequent circuit and the super capacitor (C49) 20.

[0028] The second secondary winding of the power frequency isolation multi-winding transformer (T1) 1 is connected to the communication domain power channel, which is used to power the RS-485 communication circuit. The communication domain power channel includes a rectifier diode (D9) 9, filter capacitors (C47, C44) 10, with C47's performance parameters of 220μF / 25V and C44's performance parameters of 0.1μF, and a linear regulator (U9) 11, model PJ78L05. The output of the linear regulator (U9) 11 is connected to an electrolytic capacitor (C20) 12, 10μF, and a ceramic capacitor (C51) 13, 0.1μF, to ensure transient load stability and high-frequency suppression. The communication domain power channel has an independent reference ground (G485) 23, which is electrically isolated from the ground of other domains to reduce common-mode interference in the communication loop.

[0029] The third secondary winding of the power-frequency isolation multi-winding transformer (T1) 1 is connected to the digital domain power supply channel, which is used to power the MCU and digital logic circuits. This channel includes a rectifier diode (D19) 14 and filter capacitors (C55, C25) 15, consisting of a 220μF / 25V capacitor C55 and a 0.1μF capacitor C25. It also includes a linear regulator (U7) 16, model PJ78L05. A 0.1μF ceramic capacitor (C54) 17 is connected to the output of the linear regulator (U7) 16 for output decoupling.

[0030] The main power supply channel is equipped with a backup power structure, including dual diodes (D10) 18, a current-limiting resistor (R10) 19, and a supercapacitor (C49) 20. The dual diodes (D10) 18 are BAV23S type and form an "OR" structure. Their first input is connected to the output of the linear regulator (U8) 6, and their second input is connected to the external interface (J1) 21 and the supercapacitor (C49) 20 through the current-limiting resistor (R10) 19. The current-limiting resistor (R10) 19 limits the charging current of the supercapacitor (C49) 20, protecting the power supply circuit and the supercapacitor (C49) 20. The supercapacitor (C49) 20 has a capacitance of 1.5F and a rated voltage of 5.5V. When the main power supply is disconnected, it discharges to the VDD terminal through the dual diodes (D10) 18 to maintain system operation. The external interface (J1) 21 facilitates replacement and maintenance of the supercapacitor (C49) 20.

[0031] The rectifier and voltage regulator components corresponding to each of the three secondary windings are physically isolated from each other, forming a star topology. Each capacitor is placed close to the corresponding IC pins to reduce trace inductance, thereby minimizing noise and interference. The wiring between the power-frequency isolation multi-winding transformer (T1) and the rectifier circuit is short, minimizing loop area and reducing electromagnetic radiation.

[0032] The three sets of secondary windings inside the power frequency isolation multi-winding transformer (T1) 1 are separated by physical space and isolated by insulating materials to ensure electrical safety isolation.

[0033] The working process of the present invention is as follows: when the mains power is connected, the primary side protection structure takes effect first, the self-recovery fuse (PT1) 2 limits the inrush current, and the varistor (RR1) 3 is on standby for clamping protection. The power frequency isolation multi-winding transformer (T1) 1 isolates and reduces the voltage of the mains power, and the three sets of secondary windings supply power to three independent power channels respectively. The rectifier devices of each channel convert AC power into DC power, the filter capacitor group filters out the ripple, and the linear regulator generates a stable 5V output voltage. In addition to supplying the load, the regulated output of the main power channel also charges the supercapacitor (C49) 20 through the current limiting resistor (R10) 19. When the mains power is interrupted, the supercapacitor (C49) 20 discharges to the VDD terminal through the dual diode (D10) 18 to maintain the operation of the system circuit and ensure that data is not lost.

[0034] The utility model realizes physical isolation through a multi-winding power frequency isolation multi-winding transformer (T1) 1, realizes multi-stage filtering through a combination of large and small capacitors, realizes backup power protection through a combination of dual diodes and supercapacitors, and minimizes interference through a star topology layout, thereby comprehensively forming a highly reliable, low-noise, and anti-interference multi-domain isolated power supply module for electric energy meters.

[0035] The utility model conducts the following experimental verifications on the core technical effects of the multi-domain isolated power supply module of the electric energy meter: inter-domain noise isolation performance, backup power switching reliability, anti-interference ability and compact structure.

[0036] 1. Comparative testing was used to compare the performance of the present invention with that of a conventional single-domain power supply circuit under identical operating conditions. Each test was repeated three times, and the average value was taken. The ambient temperature was 25±2°C and the humidity was 50±10%. The test equipment included a high-precision oscilloscope, spectrum analyzer, surge generator, and precision dimensional measurement tools.

[0037] 2. Technical Effect Comparison Table

[0038]

[0039] 3. Verification plan and results

[0040] Inter-domain noise isolation testing: A 10MHz / 1Vp-p interference signal was injected into the digital domain, while noise coupling was measured in the communication and control domains. The results showed that while traditional single-domain power supply attenuates noise by only 20-30dB, the multi-domain isolation structure of this utility model provides 65-80dB of isolation, effectively resolving interference issues between different functional modules.

[0041] Power-off retention test: This simulates a sudden mains outage and records the voltage curves of the three power supply domains. While traditional power supplies experience a rapid voltage drop after a power outage, falling below the 4.5V operating voltage in less than a second, the dual diode and supercapacitor combination employed by this new device maintains a stable power supply for over 25 seconds, ensuring uninterrupted circuit operation.

[0042] Interference immunity testing: IEC61000-4-5 standard surge testing was used, with the test voltage gradually increased until the device failed. Conventional single-domain power supplies fail under a 2kV surge, while the resettable fuse and varistor combination of this utility model can withstand a 5kV surge, significantly improving survivability in harsh power grid environments.

[0043] 4. Verify the conclusion

[0044] Comparative test results show that this utility model's multi-domain isolated power supply module for electric energy meters significantly outperforms traditional single-domain power supply designs in terms of inter-domain noise isolation, power-off holdover capability, anti-interference capability, and compactness. In particular, inter-domain isolation is improved by approximately 45dB, and power-off holdover time is extended by 24 times. These improvements directly address the issues of interference and power-off protection between different functional modules in electric energy meters. This fully demonstrates the practical value of this utility model's technical solution and its broad application prospects.

Claims

1. A multi-domain isolated power supply module for an electric energy meter, characterized in that: include: A power frequency isolation multi-winding transformer (T1) having a primary winding and at least three sets of secondary windings; An input protection structure provided on the primary side of the power frequency isolation multi-winding transformer (T1), comprising a self-recovery fuse (PT1) connected in series to the N line of the mains power and a varistor (RR1) connected across the AC side; A main power supply channel connected to the first group of secondary windings of the power frequency isolation multi-winding transformer (T1) comprises a rectifier bridge (D3), a filter capacitor group (C45, C46, ​​C53) and a linear regulator (U8), wherein the output end of the linear regulator (U8) is connected to an electrolytic capacitor (C48) and a ceramic capacitor (C1); A communication domain power supply channel connected to the second group of secondary windings of the power frequency isolation multi-winding transformer (T1), comprising a rectifier diode (D9), filter capacitors (C47, C44) and a linear regulator (U9), wherein the output end of the linear regulator (U9) is connected to an electrolytic capacitor (C20) and a ceramic capacitor (C51); A digital domain power supply channel connected to the third group of secondary windings of the power frequency isolation multi-winding transformer (T1), comprising a rectifier diode (D19), filter capacitors (C55, C25) and a linear regulator (U7), wherein the output end of the linear regulator (U7) is connected to a ceramic capacitor (C54); A backup power structure provided in the main power supply channel comprises a dual diode (D10), a current-limiting resistor (R10) and a super capacitor (C49); a first input end of the dual diode (D10) is connected to the output end of the linear regulator (U8); and a second input end is connected to an external interface (J1) and the super capacitor (C49) via the current-limiting resistor (R10).

2. The multi-domain isolated power supply module for electric energy meters according to claim 1, characterized in that: The three groups of secondary windings respectively have independent reference grounds, including a main power channel ground, a communication domain ground (G485) and a digital domain ground, and the reference grounds are electrically isolated from each other.

3. The multi-domain isolated power supply module for electric energy meters according to claim 1, characterized in that: The output end of the linear voltage regulator (U8) of the main power supply channel is connected to a clamping protection diode (D1) for preventing output overvoltage from damaging the super capacitor (C49).

4. The multi-domain isolated power supply module for electric energy meters according to claim 1, characterized in that: The dual diodes (D10) are BAV23S diodes, forming an "OR" structure to achieve automatic seamless switching between the main power supply and the backup power supply.

5. The multi-domain isolated power supply module for electric energy meter according to claim 1, characterized in that: The super capacitor (C49) has a capacitance of 1.5F and a rated voltage of 5.5V, and is used to discharge to the VDD terminal through the dual diodes (D10) to maintain system operation when the main power supply is cut off.

6. The multi-domain isolated power supply module for electric energy meter according to claim 1, characterized in that: The rectification and voltage stabilization components corresponding to the three groups of secondary windings are physically isolated from each other to form a star topology.

7. The multi-domain isolated power supply module for electric energy meter according to claim 1, characterized in that: The self-resetting fuse (PT1) is of FPTC type, which has the characteristics of automatically increasing resistance when overcurrent occurs and automatically recovering after the abnormality is eliminated.

8. The multi-domain isolated power supply module for electric energy meters according to claim 1, characterized in that: The varistor (RR1) is labeled 20K / 681, corresponding to a clamping voltage of 680V.

Images