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

2.1 Block Diagram

There are two configurations for the TIDA-010944 block diagram: either one- or single-phase (Phase A and Neutral, 1P2W, Wye) or split-phase (Phase A to Phase B, 2P2W, Delta) configuration.

In the split-phase configuration, the voltage is measured between Phase A and Phase B, which are 180 degrees apart.

TIDA-010944 Split-Phase Energy Measurement ConfigurationFigure 2-1 Split-Phase Energy Measurement Configuration

In the single-phase configuration the Phase (or line) A line-to-neutral voltage is directly measured, as well as the two currents on Phase A and Neutral. The non-isolated ADS131M02 standalone ADC is used to measure both current and voltage on Phase A, while the AMC131M03 only measures the current through Neutral.

A separate shunt sensor is used on each of the 2 phases for the current measurement while a simple voltage divider is used for dividing down the corresponding voltage between Phase A and Neutral or Phase A and Phase B. The selection of the shunt is made based on the current range required for the energy measurements, with common values being in the range of 150μΩ to 200μΩ, assuming that a maximum current per phase of 60A–120A has to be measured.

TIDA-010944 Single-Phase With Neutral Energy MeasurementFigure 2-2 Single-Phase With Neutral Energy Measurement

In this design, the one AMC131M03 and one ADS131M02 devices interact with the MSPM0+ MCU in the following manner:

  1. An external 16.384MHz XTAL supplies the MSPM0G1106 HFXIN and HFXOUT pins and runs through an internal divider by 2 to create the M0_CLKOUT signal, shared between both ADCs.
  2. The AMC131M03 and the ADS131M02 devices divide the CLKIN input by 2 and use this divided clock as the delta-sigma modulation clock.
  3. The SPI_SCLK (SPU Bus clock) signal (output from the MCU being the SPI controller) is fed into both ADCs to obtain synchronous SPI data transfer.
  4. The SPI_SCLK, PICO, and POCI lines are shared between the two ADCs, making sure all ADCs run synchronously on the shared SPI bus.
  5. Two separate CS lines are used, these are automatically controlled by the SPI peripheral of the MSPM0+ MCU.
  6. When new ADC samples are ready, each AMC131M03 and the ADS131M02 device assert the DRDY1 and DRDY2 output pins, which alert the MCU that new data samples are available
  7. In addition, the MCU also communicates to a PC GUI through either isolated RS232 port or non-isolated UART connection on J4.
  8. ACT and REACT output signals from the MCU represent the active and reactive energy pulses used for accuracy measurement and calibration. Both are mandatory signals needed for calibrating the electricity meter against a reference meter.