• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 82 subscribers
  • Views 1764 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

F28069 versus F28027 with DRV8305 BLDC motor booster pack.

Genatco
Guru 54057 points
Other Parts Discussed in Thread: DRV8305

Hello C2000 Piccolo group,

Does anyone know of any major difference between the F20827 or F28069 that might inflict InstaSpin motor ware?

The Piccolo F28027 WEB page suggest models ending XL have embedded support for instaSpin - is that entirely true?

Recently discovered dead band mode 6 has phase shifted center PWM alignment and causing runt pulses pwmB on TM4C1294 ePWM. Has that ever been witnessed F28027 or F28069 when ePWM is producing 3 phase motor commutation?

The DRV8305 datasheet shows a properly formed PWM signal 3 phase motor drive with what seems to be dead band enabled, page 48.

Thanks 

Slow decay CH1 95% PWM duty cycle low side FET drive and CH2 20% duty cycle high side PWM FET drive, same 1/2 bridge.

  • 0
    TI__Guru** 118000 points
    "The Piccolo F28027 WEB page suggest models ending XL have embedded support for instaSpin - is that entirely true?"
    Piccolo devices with "F" like F28027F and F28026F have InstaSPIN libraries in ROM. That is the only difference between non-F versions. Same goes for F2806x and 5x InstaSPIN enabled devices.

    I'm confused by your question relating to a TIVA Launchpad...you're asking if this same issue is seen on Piccolo F2802x?

    If you are trying to discuss an issue with the TIVA Launchpad I would ask on the TIVA forum.
  • 0 in reply to ChrisClearman
    Guru 54057 points
    HI Chris,

    Are you referring to the suffix F having embedded support?

    Issue of scope capture discovered yesterday is an actually artifact of (slow decay) mode. It is not dead band delay FED pulse as originally believed. Slow decay is highly necessary for slow rotor speeds below 500 RPM. Scopes love to trigger before that edge making it nearly impossible to capture RED/FED delays, slow decay enabled.

    Our motor will not spin at all without slow decay enabled, seems there is no real torque creating phase current to speak of. Oddly the bridge FET body diode (di/dt) end up being uniquely centered or bipolar (slow decay disable) and (di/dt) moves toward B+ high side FETS slow decay enabled.

    Do you know if the F28069F with an DRV8503 supports Slow Decay mode in the upper bridge FETS?
  • 0 in reply to Genatco
    TI__Guru** 118000 points
    "Are you referring to the suffix F having embedded support?"
    F28062F, 68F, 69F, 52F, 54F, 25F, 27F support InstaSPIN-FOC

    " Do you know if the F28069F with an DRV8503 supports Slow Decay mode in the upper bridge FETS?"
    I'll have to ask the DRV8305 team. I don't see why it wouldn't.

    You have your own motor control SW running on the TIVA Launchpad?
  • 0 in reply to ChrisClearman
    Guru 54057 points

    >You have your own motor control SW running on the TIVA Launchpad?

    Yes migrated qs-bldc and has ability to set low side drives 95% duty (slow decay) during a duty cycle update call. After trouble shooting, yet again finding pulse CH2 is in same position and is FED for both fast and slow decay modes.

    Would seem slow decay should be an embedded class function F28069F and others?

  • 0 in reply to ChrisClearman
    TI__Guru** 114905 points
    The DRV8305 does support slow decay mode in the upper bridge. The upper bridges can be enabled at 100% duty cycle.

    For more information, please refer to section 7.3.3 of the current datasheet.