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Original question:

Low Speed control of DRV8308

DRV8308: RPM of EVM

Garig Hazt
Prodigy 40 points
Part Number: DRV8308

What is the TESTED minimum and maxium rpm that I can expect to achieve with the 8308 EVM and the included BLDC motor?  What frame is the motor?

Thanks

  • 0
    TI__Guru 61280 points
    Garig,

    Please lookup the motor spec, it will be listed there. The model number of the motor can be found in the User's Guide for the EVM or on the motor itself.

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    Prodigy 40 points

    Adam,

    Prior to my message to you I had already read the EVM doc, no specs for the motor are listed concerning the RPM or the model number.  But with your response I looked in the doc again, two more times.  I do not see any specs on the motor listed, just that its a Telco Motion motor, but they manufacture many.  And if I had a motor I would have looked and not bothered posting a message here.

    Anyway it would seem to me that the design of  EVM would determine the  lowest and highest possible RPM  for the motor, I don't care about the RPM limit of the INCLUDED motor, the document states the EVM can be used with other motors.  So again, please I would like to know the design limits of the EVM's RPM. This is going to determine whether or not I am going to purchase the EVM.  This is something that I would expect the engineer of the EVM would know.

    TIA

  • 0 in reply to Garig Hazt
    Prodigy 40 points

    TI has this listed as THINKS RESOLVED, but my questions are not  Resolved. The available EVM doc does not list  any motor specs. And since I requested the motor frame size it could be assumed that I did NOT  have a motor,

    Otherwise I would have measured it and also known the RPM parameters of the EVM, and not posted here. I thought my questions were not too complicated to answer fully instead of being redirected to nowhere.   If someone could help me  with my presale questions it would be greatly appreciated.

    Thank you.

  • 0 in reply to Adam Sidelsky
    Prodigy 40 points
    I post below how to help resolve my issue
  • 0 in reply to Garig Hazt
    TI__Guru 61280 points
    Garig,

    I apologize for the frustration. The motor model information should be included in the User's Guide. Doing a quick search on E2E, I find the following thread which also has your answer:

    e2e.ti.com/.../490559

    The hardware files for the EVM in the tool folder contain the motor specs.

    That being said. The EVM doesn't have an RPM min/max as this is dictated by the number of poles that the motor has. Any BLDC motor accepting up to 32V can be used.

    From datasheet section 7.4.1: The DRV8308 device is designed to support a wide range of motor speeds and constructions. Speeds of up to
    approximately 50000 RPM are supported with motor constructions of up to 16 poles, or corresponding lower
    speeds with more poles. This translates into a Hall sensor speed of up to 6.7 kHz. (The frequency of one Hall
    sensor can be calculated by RPM × (motor poles) / 120.)

    Regards,

    -Adam