Design Da Dace a Bincike na Wuya don Meters na Noma Digital: Tafi 4kV EFT & 15kV ESD Tests

I. Gwandar​

Wani aiki yana nuna hanyar tattalin mafi yawa da ke shiga kwaikwayon digital na gida ta tsabta a wuraren kayayyakin electromagnetic mai zurfi, musamman abin da ke fito a fili a yi ayyuka da interference. Tun daga cikin birnin hardware na inganci da aka sanya, wani aiki yana soke sosai ayyukan meter a yi Electrical Fast Transient (EFT) da Electrostatic Discharge (ESD). Yana daɗe a yi ayyukan system, don in iya tabbatar da dalilin daƙiyya da yanayin kurfo, don haka ya ba a yi data mai zama da ƙungiyoyi masu shirya kan power system.

​II. Bayanin Aiki & Muhimmanci​

​1. Tabbacin Matattaccen​

Meter na gida suna da muhimmanci. An samun karshen display module da main control board baki daya da Electromagnetic Compatibility (EMC) protection measures. Wannan yana ba a yi ayyuka a immunity tests, EFT resistance ya fi yawa da industrial application requirements, wanda ya sa a yi ayyuka a wurare da real-world distribution environments.

​2. Muhimmancin Mafi Yawa​

• ​Yawan Performance:​​ Soke sosai ayyukan meter na EMC, domin ya fi iya pass Level 4 kV EFT tests da high-level ESD tests.
• ​Ayyukan Ayyuka:​​ Ba da ayyukan ayyuka a meters a wurare da transient pulses da electrostatic interference, domin ya ba a yi data acquisition da transmission.
• ​Yawan Structure:​​ Simplify circuit design, reduce the number of external components, and control/lower hardware costs while enhancing performance.

​III. Overall System Architecture​

Ya fara aiki a modular design da take da main control chip, wanda yana da structure mai sauƙi da responsibilities. It mainly includes the following core units:

• ​Main Control Unit:​​ The "brain" of the system, responsible for data calculation, logic control, and system scheduling.
• ​Signal Acquisition Unit:​​ Responsible for acquiring and performing preliminary processing of raw three-phase voltage and current signals from the power grid.
• ​Power Management Unit:​​ Provides stable, isolated multi-channel working power for all functional modules.
• ​Human-Machine Interaction (HMI) Unit:​​ Includes the display control module for local parameter display.
• ​Data Communication Unit:​​ Provides an RS485 interface for data exchange with remote monitoring systems.
• ​Data Storage & Clock Unit:​​ Used for storing historical data and providing a precise time reference.
• ​Key Innovation: Dedicated Anti-interference Module:​​ A core aspect of this solution, adding protective modules for critical signal paths.

​IV. Key Technological Breakthroughs​

​1. Dedicated Anti-EFT Filter Circuit Design​

• ​Innovative Approach:​​ Precisely identified the communication lines between the display control module and the main control chip as the vulnerable point for EFT intrusion. Accordingly, we designed independent filtering channels for each communication signal line.
• ​Implementation:​​ A capacitor of a specific value is connected in parallel from each communication line to ground, forming a simple low-pass filter network. This capacitor effectively absorbs the high-frequency spike energy generated by EFT on the signal lines, thereby protecting the main control chip interface from interference.
• ​Result:​​ This extremely low-cost design elevates the meter's EFT immunity to 4 kV, resolving the shortcoming of traditional meters in this area.

​2. System-Level Anti-interference Optimization for Main Control​

• ​Clock Circuit Optimization:​​ Abandoned the traditional use of interference-prone high-frequency crystals, opting instead for a low-frequency crystal as the main clock source. Low-frequency clock signals inherently possess stronger anti-interference capability, reducing the probability of system-level impact.
• ​System Integration Simplification:​​ Fully leveraged the high integration of modern main control chips. The internal integration of the Analog-to-Digital Converter (ADC) and oscillator compensation capacitors eliminates the need for external discrete components.
• ​Comprehensive Benefits:​​
• The optimized clock circuit greatly enhances the meter's ability to resist external electrostatic interference, allowing it to easily pass the highest level ESD tests.
• The highly integrated design simplifies PCB layout, reduces component count, thereby not only lowering material costs but also improving production efficiency and overall reliability.

​V. Solution Advantages & Value​

​1. Exceptional Reliability​

• Capable of stable operation in EFT interference environments exceeding 4 kV and ESD environments exceeding 15 kV, meeting the most stringent industrial standards.
• The optimized hardware foundation ensures timing accuracy in data acquisition and long-term stability of measurements.

​2. Significant Economical Efficiency​

• Directly reduces material procurement costs by reducing the number of external components.
• The simplified design improves production first-pass yield and reduces post-sales maintenance costs, providing customers with a life-cycle cost advantage.

​3. Excellent Manufacturability​

• The anti-interference measures employed use standard, mature, general-purpose components. The design is simple and reliable, making it highly suitable for large-scale mass production, ensuring product consistency and high quality.