TIDUF72 August   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
    2. 1.2 End Equipment
    3. 1.3 Electricity Meter
    4. 1.4 Power Quality Meter, Power Quality Analyzer
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Magnetic Tamper Detection With TMAG5273 Linear 3D Hall-Effect Sensor
      2. 2.2.2 Analog Inputs of Standalone ADCs
      3. 2.2.3 Voltage Measurement Analog Front End
      4. 2.2.4 Analog Front End for Current Measurement
    3. 2.3 Highlighted Products
      1. 2.3.1 AMC131M03
      2. 2.3.2 ADS131M02
      3. 2.3.3 MSPM0G1106
      4. 2.3.4 TMAG5273
      5. 2.3.5 ISO6731
      6. 2.3.6 TRS3232E
      7. 2.3.7 TPS709
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1  Software Requirements
      2. 3.1.2  UART for PC GUI Communication
      3. 3.1.3  Direct Memory Access (DMA)
      4. 3.1.4  ADC Setup
      5. 3.1.5  Foreground Process
      6. 3.1.6  Formulas
        1. 3.1.6.1 Standard Metrology Parameters
        2. 3.1.6.2 Power Quality Formulas
      7. 3.1.7  Background Process
      8. 3.1.8  Software Function per_sample_dsp()
      9. 3.1.9  Voltage and Current Signals
      10. 3.1.10 Pure Waveform Samples
      11. 3.1.11 Frequency Measurement and Cycle Tracking
      12. 3.1.12 LED Pulse Generation
      13. 3.1.13 Phase Compensation
    2. 3.2 Test Setup
      1. 3.2.1 Power Supply Options and Jumper Setting
      2. 3.2.2 Electricity Meter Metrology Accuracy Testing
      3. 3.2.3 Viewing Metrology Readings and Calibration
        1. 3.2.3.1 Calibrating and Viewing Results From PC
      4. 3.2.4 Calibration and FLASH Settings for MSPM0+ MCU
      5. 3.2.5 Gain Calibration
      6. 3.2.6 Voltage and Current Gain Calibration
      7. 3.2.7 Active Power Gain Calibration
      8. 3.2.8 Offset Calibration
      9. 3.2.9 Phase Calibration
    3. 3.3 Test Results
      1. 3.3.1 Energy Metrology Accuracy Results
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
      3. 4.1.3 PCB Layout Recommendations
      4. 4.1.4 Layout Prints
      5. 4.1.5 Altium Project
      6. 4.1.6 Gerber Files
      7. 4.1.7 Assembly Drawings
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Authors

1.3 Electricity Meter

Utility providers and customers are driving the need for more features from electricity meters. As the accuracy requirements and amount of processing expected from electricity meters rapidly increase, it becomes more and more difficult to solve these issues with a single metrology system-on-chip (SoC). A dual-chip approach with a standalone ADC and a host microcontroller (MCU) helps overcome the limitations of electricity meter SoCs and enables a mix-and-match solution, which can be optimized for cost or performance.

Using an accurate state-of-the-art standalone ADC with integrated power and data isolation, such as the AMC131M03, has the following advantages:

  • Enables meeting the most stringent of accuracy requirements
  • Enables meeting minimum sample rate requirements (without compromising on accuracy) that is sometimes not obtainable with application-specific products or metrology SoCs
  • Enables flexibility in selecting the host MCU, based on the application requirements, such as processing capability in million instructions per second (MIPS), minimum random access memory (RAM) and flash area, the number of communications modules (for example, serial peripheral interface (SPI), universal asynchronous receiver - transmitter (UART), and inter-integrated circuit (I2C), real-time clock (RTC), and continuously transposed conductors (CRC) module.

To properly measure energy consumption, voltage, and current sensors, translate mains voltage and current to a voltage range that an ADC can detect. When a multiphase power distribution system is used, it is necessary for the current sensors to be isolated from phase-to-phase, so the sensors can properly detect the current drawn from one or two different lines (when neutral is measured or in split-phase configuration) without damaging the ADCs. This design uses two cost-effective shunt sensors, which are immune to magnetic tampering, and enables the implementation of electricity meters for single-phase with optional neutral line measurement or split-phase meters with two currents and a single voltage configuration.

TIDA-010944 is a class 0.2 S high-accuracy one-phase or split-phase SHUNT electricity meter reference design, using one three-channel standalone isolated AMC131M03 ADC, one non-isolated two-channel standalone ADS131M02 ADC, and a cost-effective MSPM0G1106 MCU. The reference design can also be used for energy metering in popular products such as electric vehicle (EV) chargers and AC wall boxes. The non-isolated ADCs senses the current and the voltage on Phase A, while the non-isolated ADC is used for current monitoring of the Neutral line or Phase B, depending on which configuration is used.

The TIDA-010944 firmware specifically supports calculation of various metrology parameters for single-phase with Neutral line or split-phase energy measurement. These parameters can be viewed from the calibration GUI or through the ACT and REACT pulsed outputs, connected to a reference metrology test system.

  • Total and per-phase active (kWh), reactive (kvarh), and apparent energy (kVAh) with pulse-generation outputs
  • Total and per-phase active (kW), reactive (kvar), and apparent power (kVA)
  • Per-phase voltage and current root mean square (RMS)
  • Power factor
  • Line frequency