SBOA444 November   2020 TMCS1100

 

  1.   Trademarks
  2. 1Introduction
  3. 2Implementation Block Diagram
  4. 3Hardware Implemenation
    1. 3.1 Analog Inputs
      1. 3.1.1 Voltage Measurement Analog Front End
      2. 3.1.2 Current Measurement Analog Front End
    2. 3.2 MSP432 LaunchPad Connections
    3. 3.3 PCB Layout Recommendations
  5. 4How to Implement Software for Metrology Testing
    1. 4.1 Setup
      1. 4.1.1 Clock
      2. 4.1.2 UART Setup for GUI Communication
      3. 4.1.3 Real-Time Clock (RTC)
      4. 4.1.4 Direct Memory Access (DMA)
      5. 4.1.5 ADC Setup
    2. 4.2 Foreground Process
      1. 4.2.1 Formulas
        1. 4.2.1.1 Standard Metrology Parameters
        2. 4.2.1.2 Power Quality Formulas
    3. 4.3 Background Process
      1. 4.3.1 per_sample_dsp( )
        1. 4.3.1.1 Voltage and Current ADC Samples
        2. 4.3.1.2 Pure Waveform Samples
        3. 4.3.1.3 Frequency Measurement and Cycle Tracking
      2. 4.3.2 LED Pulse Generation
      3. 4.3.3 Phase Compensation
  6. 5Metrology Accuracy Testing
    1. 5.1 Test Setup
    2. 5.2 Results
  7. 6Schematics
  8. 7References

3.1 Analog Inputs

Each of the ADS131M08 converters is differential and requires that the input voltages at its pins does not exceed ±1.2 V (assuming an internal PGA gain setting of 1 is used). To meet this input voltage specification, a voltage and current sensor circuit is needed to translate the Mains voltage and outlet current into a voltage that can be sensed by the ADS131M08. This subsection describes the analog front end used for voltage and current channels.