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

3.2.1.5 Rotor Flux Position

Knowledge of the rotor flux position is the core of the FOC. In fact if there is an error in this variable the rotor flux is not aligned with the d-axis and isd and isq are incorrect flux and torque components of the stator current. Figure 3-10 shows the (a, b, c), (α, β) and (d, q) reference frames, and the correct position of the rotor flux, the stator current and stator voltage space vector that rotates with d,q reference at synchronous speed.

TIDA-010282 Current, Voltage and Rotor Flux Space Vectors in the (d, q) Rotating Reference FrameFigure 3-10 Current, Voltage and Rotor Flux Space Vectors in the (d, q) Rotating Reference Frame

The measure of the rotor flux position is different when considering the synchronous or asynchronous motor:

  • In the synchronous machine the rotor speed is equal to the rotor flux speed. Then θ (rotor flux position) is directly measured by the position sensor or by integration of rotor speed.
  • In the asynchronous machine the rotor speed is not equal to the rotor flux speed (there is a slip speed), then this needs a particular method to calculate θ. The basic method is the use of the current model which needs two equations of the motor model in the d, q reference frame.

Theoretically, the FOC for the PMSM drive allows the motor torque be controlled independently with the flux like DC motor operation. In other words, the torque and flux are decoupled from each other. The rotor position is required for variable transformation from the stationary reference frame to the synchronously rotating reference frame. As a result of this transformation (so called Park transformation), q-axis current can be controlling torque while d-axis current is forced to zero. Therefore, the key module of this system is the estimation of rotor position using enhance Sliding-Mode Observer (eSMO) or FAST estimator.

Figure 3-11 shows the overall block diagram of sensorless FOC of fan PMSM using eSMO with flying start.

Figure 3-12 shows the overall block diagram of sensorless FOC of compressor PMSM using eSMO with field weakening control (FWC) and maximum torque per ampere (MTPA) .

Figure 3-13 shows the overall block diagram of sensorless FOC of fan PMSM using FAST with flying start.

TIDA-010282 Sensorless FOC of Fan PMSM Using eSMO With Flying Start (FS)Figure 3-11 Sensorless FOC of Fan PMSM Using eSMO With Flying Start (FS)
TIDA-010282 Sensorless FOC of compressor PMSM Using eSMO With FWC and MTPAFigure 3-12 Sensorless FOC of compressor PMSM Using eSMO With FWC and MTPA
TIDA-010282 Sensorless FOC of Fan PMSM using FAST with Flying Start (FS)Figure 3-13 Sensorless FOC of Fan PMSM using FAST with Flying Start (FS)