SLLA663 March   2025 MCF8315A , MCF8315C , MCF8315C-Q1 , MCF8315D , MCF8316A , MCF8316C-Q1 , MCF8316D , MCF8329A , MCT8315A , MCT8316A , MCT8329A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2End Application Configuration Recommendation
    1. 2.1 Resynchronization
    2. 2.2 Reverse Drive
    3. 2.3 Coasting (Hi-Z)
    4. 2.4 Startup Brake
    5. 2.5 Direction Change Mode
  6. 3Tuning Guidance
    1. 3.1 Initial Speed Detection Module
      1. 3.1.1 Initial Speed Detection
      2. 3.1.2 ISD Times
      3. 3.1.3 Stationary Detect Threshold
    2. 3.2 Resynchronization
      1. 3.2.1 Forward Drive Resync Threshold
      2. 3.2.2 Reverse Drive
      3. 3.2.3 Reverse Acceleration Parameters
      4. 3.2.4 Reverse Drive Current Limits
      5. 3.2.5 Reverse Drive Handoff Threshold
      6. 3.2.6 Reverse Drive Open Loop Deceleration (REV_DRV_OPEN_LOOP _DEC)
    3. 3.3 Coasting (Hi-Z)
    4. 3.4 Brake
      1. 3.4.1 Brake Config (BRK_CONFIG)
  7. 4Feature Availability of MCx Devices
    1. 4.1 FOC Family (MCF83xx devices)
    2. 4.2 TRAP Family (MCT83xx devices)
  8. 5Summary
  9. 6References

3.2 Resynchronization

If the motor is already spinning in the commanded direction, resynchronization feature enables us to sync the motor to the drive and ramp to commanded speed. The available configurations are described in Table 3-2.

Table 3-2 Resync Related Configurations
Configuration Sub-Feature Description Tuning Considerations
RESYNC_EN If the motor is spinning forward (same direction as the commanded direction) with sufficient speed (BEMF), this feature resynchronizes with the spinning motor. Enable for applications that use high inertia motors like Fans.
FWD_DRV_RESYN_THR If motor speed > FWD_DRV_RESYN_THR, then device can go to resynchronize directly to closed loop otherwise the device can go for open loop drive before closed loop operation. FWD_DRV_RESYN_THR needs to be the same as OPN_CL_HANDOFF_THR as this is expected to be the minimum speed where BEMF is reliable enough to transition to closed loop. If set too low, device can have reliability issues as closed loop can fail due to unreliable BEMF. If set too high, device forces open loop drive even though BEMF is reliable and closed loop drive is possible. Note: BEMF generated = BEMF constant of the motor * motor speed. Make sure speed is sufficient to generate few 100mV at FWD_DRV_RESYN_THR as per motor BEMF constant.