SLVAFO8A April   2024  – May 2024 DRV8214 , DRV8234

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction: Need for Sensorless Designs
  5. 2Ripple Counting − Concept
    1. 2.1 Ripple Counting Algorithm Details
  6. 3Case Study: Robotic Wheel Drive
    1. 3.1 Robotic Wheel Motor Operating Conditions
    2. 3.2 Tuning Parameters for Ripple Counting
      1. 3.2.1 Resistance Parameters
      2. 3.2.2 KMC and KMC_SCALE
        1. 3.2.2.1 Tuning KMC_SCALE
        2. 3.2.2.2 Tuning KMC
    3. 3.3 Robotic Wheel Motor with Ripple Counting
      1. 3.3.1 Inrush and Steady State Performance
        1. 3.3.1.1 Motor Speed Calculation
      2. 3.3.2 Soft Start
      3. 3.3.3 Loaded Conditions
  7. 4Challenges and Workarounds
    1. 4.1 Low Average Currents
    2. 4.2 Motor Inertia During Stop
    3. 4.3 Inrush
    4. 4.4 High Load Conditions
  8. 5Summary
  9. 6References
  10. 7Revision History

3.2.2 KMC and KMC_SCALE

Selection of KMC_SCALE and KMC can be divided into two cases:

  1. Value of the motor back emf constant, KV is known to the user from the data sheet of the motor. Please refer to section 8.2.3.1.2.1 in DRV8234 data sheet for the tuning guide in this case.
  2. Value of the motor back emf constant, KV is unknown to the user. Please refer to section 8.2.3.1.2.2.1 in DRV8234 data sheet for the tuning guide in this case.

For the robot wheel motor, the value of KV was unknown. Thus, step 2 was followed. KMC and KMC_SCALE need to be tuned manually from scratch. Both parameters are reset at the start before tuning is begun.