SLLA665 April   2025 MCF8315A , MCF8315C , MCF8315C-Q1 , MCF8315D , MCF8316A , MCF8316C-Q1 , MCF8316D , MCF8329A , MCF8329A-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Open Loop and Handoff Stage
  5. 2EEPROM Configurations Affecting Open Loop to Closed Loop Handoff
  6. 3Open Loop to Closed Loop Handoff Tuning
    1. 3.1 Experimental Way to Tune Open Loop and Handoff Stage
      1. 3.1.1 Step-1: Initial Configuration
      2. 3.1.2 Step-2: Tuning of Parameters In Case Handoff is not Proper
        1. 3.1.2.1 Tuning of OL_ILIMIT
        2. 3.1.2.2 Tuning of Open Loop Acceleration Co-Efficient A1
        3. 3.1.2.3 Tuning of Handoff Thresholds
      3. 3.1.3 Step-3: Tuning of Handoff Configurations
  7. 4Optimum Handoff
    1. 4.1 Open Loop Time With the Recommended Settings
    2. 4.2 Open Loop Time by Following Optimum Handoff Steps
  8. 5Summary
  9. 6References

3.1.1 Step-1: Initial Configuration

  1. Set open loop OL_ILIMIT to 0.5×(rated motor peak phase current)A.
  2. Set maximum speed of motor in MAX_SPEED configuration and then set OPN_CL_HANDOFF_THR to 20%.
  3. Set OL_ACC_A1 equal to (MAX_SPEED/10)Hz/s and OL_ACC_A2 to zero.
  4. Use the DACOUT1 and DACOUT2 pins to plot SPEED_FDBK and SPEED_REF_OPEN_LOOP variables on the DAC of the MCF83xx, with 8/8 scaling (bipolar), and probe them on an oscilloscope.

Give speed command to MCF83xx device, and capture the behavior of Motor Speed (FG_TRACK), Motor phase current (OUTA), SPEED_FDBK, and SPEED_REF_OPEN_LOOP variables. Observe if SPEED_FDBK is tracking SPEED_REF_OPEN_LOOP by the end of open loop, for at least 30% of open loop time. This makes sure check-points 1 and 2 are met.

MOTOR1: Rated current = 1A, Maximum speed =300Hz. Figure 3-1 demonstrates a proper handoff

Note: The trace FG_TRACK is a mathematically computed signal which tracks the frequency of the FG output signal (C1).
Proper Handoff - OL_ILIMIT = 0.5, OL_ACC_A1 = 25Hz/sec, OPN_CL_HANDOFF_THR = 20% Figure 3-1 Proper Handoff - OL_ILIMIT = 0.5, OL_ACC_A1 = 25Hz/sec, OPN_CL_HANDOFF_THR = 20%

If you do not see this happening, please go to step-2, to understand the parameters to be tuned and in which direction, based on the motor behavior.