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Evaluating InstaSPIN FOC for Traction Drive

Elliott Partridge
Prodigy 195 points
I'm trying to hunt down some answers to specific questions on InstaSPIN:
  1. How much code/RAM space is left after the burned-in InstaSPIN library?
  2. Where and how is angle selection made (FOC estimator vs sensor angle)?
  3. What are the limits on current measurement as far as scaling, dynamic range, and resolution?
  4. Can HFI/FOC be used to provide more fine-grained angle estimation along with a hall-sensor providing coarser angle feedback?
Thanks,
Elliott
  • 0
    Prodigy 195 points
    Found some answers (please correct if I am wrong):
    1. FOC & MOTION each use a separate 32KB block of ROM, which does not take up any user code space. Only 2KB of RAM is used by either library.
    2. FAST provides an angle estimate only; it does not integrate sensor feedback into its estimation strategy.
  • 0 in reply to Elliott Partridge
    TI__Guru** 119680 points
    1. The libraries are in on-chip ROM. The example projects we provide are a baseline and will take up some user memory. A portion of this must remain in RAM. Your own code can be added and can be distributed between RAM and FLASH.

    2. In the project that use an encoder (like proj_lab12 and 13) FAST is still being run, so you can compare the feedback from FAST and the sensor. You will need to review the code to see how this is implemented with the SpinTAC functions.

    3. When using FAST you need to maximize the resolution of the ADC signals for the best results. Don't over-build your scaling where the resolution of your measurements will be poor.

    4. The HFI function is very, very challenging to get working in a real application. It requires a very specific motor with incredibly high saliency and user motor control experience. I will caution you on that before you spend much effort on this topic.

    For most traction drives you will need to use mechanical sensors to get an acceptable start-up experience, especially if it is something that a human is transported on. If it's a machine that just has to start-up and it can be a little bit rough; or if the motor produces much more torque than any expected load sensorless could be used.