SPRUJ26A September   2021  – April 2024

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Motor Control Theory
    1. 2.1 Mathematical Model and FOC Structure of PMSM
    2. 2.2 Field Oriented Control of PM Synchronous Motor
    3. 2.3 Sensorless Control of PM Synchronous Motor
      1. 2.3.1 Enhanced Sliding Mode Observer with Phase Locked Loop
        1. 2.3.1.1 Design of ESMO for PMSM
        2. 2.3.1.2 Rotor Position and Speed Estimation With PLL
    4. 2.4 Hardware Prerequisites for Motor Drive
      1. 2.4.1 Motor Phase Voltage Feedback
    5. 2.5 Additional Control Features
      1. 2.5.1 Field Weakening (FW) and Maximum Torque Per Ampere (MTPA) Control
      2. 2.5.2 Flying Start
  6. 3Running the Universal Lab on TI Hardware Kits
    1. 3.1 Supported TI Motor Evaluation Kits
    2. 3.2 Hardware Board Setup
      1. 3.2.1  LAUNCHXL-F280025C Setup
      2. 3.2.2  LAUNCHXL-F280039C Setup
      3. 3.2.3  LAUNCHXL-F2800137 Setup
      4. 3.2.4  TMDSCNCD280025C Setup
      5. 3.2.5  TMDSCNCD280039C Setup
      6. 3.2.6  TMDSCNCD2800137 Setup
      7. 3.2.7  TMDSADAP180TO100 Setup
      8. 3.2.8  DRV8329AEVM Setup
      9. 3.2.9  BOOSTXL-DRV8323RH Setup
      10. 3.2.10 BOOSTXL-DRV8323RS Setup
      11. 3.2.11 DRV8353RS-EVM Setup
      12. 3.2.12 BOOSTXL-3PHGANINV Setup
      13. 3.2.13 DRV8316REVM Setup
      14. 3.2.14 TMDSHVMTRINSPIN Setup
      15.      34
      16.      35
    3. 3.3 Lab Software Implementation
      1. 3.3.1 Importing and Configuring Project
      2.      38
      3.      39
      4. 3.3.2 Lab Project Structure
      5. 3.3.3 Lab Software Overview
    4. 3.4 Monitoring Feedback or Control Variables
      1. 3.4.1 Using DATALOG Function
      2. 3.4.2 Using PWMDAC Function
      3. 3.4.3 Using External DAC Board
    5. 3.5 Running the Project Incrementally Using Different Build Levels
      1. 3.5.1 Level 1 Incremental Build
        1. 3.5.1.1 Build and Load Project
        2. 3.5.1.2 Setup Debug Environment Windows
        3. 3.5.1.3 Run the Code
      2. 3.5.2 Level 2 Incremental Build
        1. 3.5.2.1 Build and Load Project
        2. 3.5.2.2 Setup Debug Environment Windows
        3. 3.5.2.3 Run the Code
      3. 3.5.3 Level 3 Incremental Build
        1. 3.5.3.1 Build and Load Project
        2. 3.5.3.2 Setup Debug Environment Windows
        3. 3.5.3.3 Run the Code
      4. 3.5.4 Level 4 Incremental Build
        1. 3.5.4.1 Build and Load Project
        2. 3.5.4.2 Setup Debug Environment Windows
        3. 3.5.4.3 Run the Code
  7. 4Building a Custom Board
    1. 4.1 Building a New Custom Board
      1. 4.1.1 Hardware Setup
      2. 4.1.2 Migrating Reference Code to a Custom Board
        1. 4.1.2.1 Setting Hardware Board Parameters
        2. 4.1.2.2 Modifying Motor Control Parameters
        3. 4.1.2.3 Changing Pin Assignment
        4. 4.1.2.4 Configuring the PWM Module
        5. 4.1.2.5 Configuring the ADC Module
        6. 4.1.2.6 Configuring the CMPSS Module
        7. 4.1.2.7 Configuring Fault Protection Function
      3. 4.1.3 Adding Additional Functionality to Motor Control Project
        1. 4.1.3.1 Adding Push Buttons Functionality
        2. 4.1.3.2 Adding Potentiometer Read Functionality
        3. 4.1.3.3 Adding CAN Functionality
    2. 4.2 Supporting New BLDC Motor Driver Board
    3. 4.3 Porting Reference Code to New C2000 MCU
  8.   A Appendix A. Motor Control Parameters
  9.   References
  10.   Revision History

2.5.2 Flying Start

Flying start is a feature that allows the drive to determine the speed and direction of a spinning motor and begin the output voltage and frequency at that speed and direction. Without flying start, the drive will begin its output at zero volts and zero speed and attempt to ramp to the commanded speed. If the inertia or direction of rotation of a load requires the motor to produce a large amount of torque, excess current can result and overcurrent trips might occur on the drive. These problems can be eliminated with flying start.

Flying start is the capacity to start control at any speed other than ZERO, which is an important function in air-condition application for fan drive.

When a motor is started in its normal mode, the control initially applies a frequency of 0 Hz and ramps to the desired frequency. If the drive is started in this mode with the motor already spinning with non-zero frequency, large currents are generated. An over current trip can result if the current limiter cannot react quickly enough. Even if the current limiter is fast enough to prevent an over current trip, it can take an unacceptable amount of time for synchronization to occur and for the motor to reach its desired frequency. In addition, larger mechanical stress is placed on the application.

In flying start mode, the drive’s response to a start command is to synchronize with the motor’s speed (frequency and phase) and voltage. The motor then accelerates to the commanded frequency. This process prevents an over current trip and significantly reduces the time for the motor to reach its commanded frequency. Because the drive synchronizes with the motor at its rotating speed and ramps to the proper speed, little or no mechanical stress are present.

The flying start function implements an algorithm that searches for the rotor speed. The algorithm searches for a motor voltage that corresponds with the excitation current applied to the motor

When the motor is spinning, the speed and position information can be estimated from the BEMF voltages. Since the stator voltage is measured in InstaSPIN drive, the speed and position are easily obtained by switching the inverter. A zero torque current is applied to the motor and the generated current and stator voltage is measured, then InstaSPIN-FOC module uses these signals to estimate rotor position and speed.

The block diagram of FOC with flying start is shown in Figure 2-23, the flying start module outputs a flag to enable or disable speed close loop control. A zero reference torque current is set and the speed PI controller output is disabled while flying start is operating.

Flying Start Control Block Diagram Figure 2-23 Flying Start Control Block Diagram

As shown in Figure 2-24, the module routine disables speed close loop control, sets the reference Iq to zero, and enables the FOC module during starting run the motor. After the phase currents and voltages are measured, the routine runs InstaSPIN-FOC and the real motor speed can be estimated. The program re-enables speed closed loop control and sets the speed reference value after flying start is completed.

Flying Start Module Program Flowchart Figure 2-24 Flying Start Module Program Flowchart