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Help with a Low Inductance, High Speed Motor

William Smith69
Prodigy 20 points

Part Number: DRV8312-69M-KIT
Other Parts Discussed in Thread: MOTORWARE

PSI has developed a pump which is attracting investor interest.  Our biggest problem is that conventional brushless, sensorless DC motor drivers run the pump poorly.  Motor inductance about 10 microhenries, speed range 10,000 - 60000 rpm.  After some research, I bought the subject kit as a promising candidate.  Ran the kit motor fine.  Trying to work through the labs, but very, very slow for me; totally out of my depth.  At this point I don't need to develop the controller, just show that I can run the pump reliably.  Is there somebody who can help me get through the the motor identification phase so I can make this motor run with the kit set up.  If/when the investment comes we will hire an EE or a consultant (or both) to go farther towards a product.

  • 0
    TI__Guru** 116860 points
    What's the rated power, current and voltage of the motor? You might try InstaSPIN-FOC for this application, please download motorWare from below link, you could find instaSPIN lab guide in the folder, and then follow the guide to run the related lab project, you might spin your motor in just minutes. You may have a look at the Video to get more information about the InstaSPIN-FOC solution.

    www.ti.com/.../motorware

    And you may select an EVM kit based on your motor as below link.
    www.ti.com/.../instaspin.html
  • 0 in reply to Yanming Luo
    Prodigy 20 points
    I have tried to work thru InstaSPIN and I have Motorware on my computer. I believe it should be possible to get the motor spinning in minutes, but as I noted in my original message I am struggling with the lab exercises due to an utter lack of experience. I keep getting lost in the menus.

    The nominal voltage is 12 V, the current runs around 2 amps, and therefore the power is about 24 watts.
  • 0 in reply to William Smith69
    TI__Guru** 116860 points
    You could use DRV8312-Kit with F28069M ControlCard, just run lab02c to identify motor parameters, and run lab05b or lab10a to implement speed close loop control as you required. Please go ahead and let me know if you have any further question, and post a detailed description of your application process. Thanks.
    www.ti.com/.../drv8312-69m-kit
  • 0 in reply to Yanming Luo
    TI__Guru** 116860 points

    Just wanted to check in and see if there is any update from your side, I haven’t heard from you for two weeks, so I’m assuming you were able to resolve your issue. Please let me know if you have any questions. We would like to close this thread if no any further questions. Thanks.

  • 0 in reply to Yanming Luo
    Intellectual 310 points

    We are very confused  about current measurements. In SPRUHJ1G 4.1.5, 5.1.3, and 5.2.1 seem to define current measurements in different ways. Sometimes it says current, sometimes it says peak current and in one place it says peak to peak current. So, unless otherwise specified are we to assume peak current? 

    If the custom board is set up to measure is 9.9 A RMS ( +/-14 A Peak) at ADC saturation, what is the correct value to put into USER_IQ_FULL_SCALE_CURRENT_A, 14 A or 28 A? Does 5.2.1 code snippet have it right? Or does the first code snippet in 5.1.3 have it right?
  • 0 in reply to David Larson
    TI__Guru** 116860 points
    USER_IQ_FULL_SCALE_CURRENT_A is not a critical value in an instaSPIN project. You need to set a correct USER_ADC_FULL_SCALE_CURRENT_A based on the hardware board, it is based on the current sensing and scaling to the ADC
    input. And then you could set USER_IQ_FULL_SCALE_CURRENT_A to half of USER_ADC_FULL_SCALE_CURRENT_A. So the hardware should have enough sensing range that is higher than the maximum peak-peak current with a few headroom.