TIDUFE5 July   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1  TMS320F2800137
      2. 2.3.2  LMG3651R025
      3. 2.3.3  LMG2650
      4. 2.3.4  TMCS1126
      5. 2.3.5  ISO6721
      6. 2.3.6  UCC28881
      7. 2.3.7  UCC27712
      8. 2.3.8  TPS562206
      9. 2.3.9  TLV9062
      10. 2.3.10 TLV74033
  9. 3System Design Theory
    1. 3.1 Totem Pole PFC
      1. 3.1.1 Inductor Ratings
      2. 3.1.2 AC Voltage Sensing
      3. 3.1.3 DC Link Voltage Sensing
      4. 3.1.4 AC Current Sensing
      5. 3.1.5 DC Link Capacitor Rating
    2. 3.2 Three-Phase PMSM Drive
      1. 3.2.1 Field Oriented Control of PM Synchronous Motor
        1. 3.2.1.1 Space Vector Definition and Projection
        2. 3.2.1.2 Clarke Transformation
        3. 3.2.1.3 Park Transformation
        4. 3.2.1.4 Basic Scheme of FOC for AC Motor
        5. 3.2.1.5 Rotor Flux Position
      2. 3.2.2 Sensorless Control of PM Synchronous Motor
        1. 3.2.2.1 Enhanced Sliding Mode Observer With Phase Locked Loop
          1. 3.2.2.1.1 Mathematical Model and FOC Structure of an IPMSM
          2. 3.2.2.1.2 Design of ESMO for the IPMSM
          3. 3.2.2.1.3 Rotor Position and Speed Estimation With PLL
      3. 3.2.3 Hardware Prerequisites for Motor Drive
        1. 3.2.3.1 Current Sensing With Three-Shunt
        2. 3.2.3.2 Motor Voltage Feedback
  10. 4Hardware, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 Hardware Board Overview
      2. 4.1.2 Test Conditions
      3. 4.1.3 Test Equipment Required for Board Validation
    2. 4.2 Test Setup
    3. 4.3 Test Results
      1. 4.3.1 Functional Waveforms
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 Bill of Materials
      3. 5.1.3 Altium Project
      4. 5.1.4 Gerber Files
      5. 5.1.5 PCB Layout Recommendations
    2. 5.2 Tools
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

3.1.4 AC Current Sensing

The AC current sensing circuit is used to convert the PFC inductor current signal into a low voltage signal, and then to condition the sensed signal to meet the requirements of the ADC input port. As part of PFC inner current loop control, AC current sensing is crucial for both bandwidth and accuracy. A TMCS1126B4 is used for AC current sensing as shown in Figure 3-3.

TIDA-010282 PFC AC Current Sensing CircuitFigure 3-3 PFC AC Current Sensing Circuit
  • AC current gain, the TMCS1126B4 has 100mV/A sensitivity.
Equation 5. V P F C _ I A C = I A C _ P F C × G i
Equation 6. VPFC_IAC = 0.1 × IAC