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InstaSpin FOC timing advancement

Gary H
Expert 1855 points

Other Parts Discussed in Thread: INSTASPIN-BLDC

 

My motor supplier is telling me that some customers have been able to squeeze out some more efficiency on their motor by using “FOC timing advancement”. I was able to manually adjust the Kslide in our old SMO motor drive and could get a little more efficient while running our system. I think this is what they are referring too. Just wondering if this “FOC timing advancement” is the same as adjusting the Kslide in the old SMO drive and if so, can and should I do something similar in the InstaSpin FOC?

In our previous SMO drive I would bring our system up with the calculated SMO parameters and then while our system was running steady state, I would tweak the Kslide to get maximum efficiency. If I was going to try to manually tweak the Instapin FOC, what would I adjust and what procedure would I follow. The motor seems to be running fine with the auto motor identify parameters, but just wondering if there is any manual tweaking that can be done?

  • 0
    TI__Guru** 119680 points
    Gary,
    Is this for operation at higher speeds? If so, back in release 9 we added phase delay compensation. This adds on a delta angle to the angle from FAST to compensate for the additional angle rotation that occurs from the sample to the PWM output. This is built in to the CTRL code for any project NOT running the CTRL out of ROM (proj_lab02b+).

    The only compensation you can make to the observer is to
    1. run RsOnline so it is always using latest Rs value
    2. manually load new values for Ls_d and Ls_q based on the current/torque operating point.

    There are some additional things that customers do from the CONTROL loop standpoint (cross coupled current controllers, various other forward/feedback control schemes, different modulation) that can increase efficiency in certain applications.
  • 0 in reply to ChrisClearman
    Expert 1855 points
    Not really. We are only running at a Max of 1700 RPM. I do believe the application my supplier is referring to is in some of their other motors that are used in blower applications the speeds can reach 20,000+ RPM. This is probably where there customers are using Phase delay or “Timing advancement”.

    I am currently using the Rs_Online and it seems to work great. I will explore some of your other suggestions and see what we get, but for now I am happy with the efficiencies we are getting and would probably not gain much by tweaking things. I just wanted to make sure I understood their suggestion and make it sound like I know what I am talking about when I reply:)
  • 0 in reply to Gary H
    TI__Guru** 119680 points
    yes, phase advancement is a BLDC technique. If you were using InstaSPIN-BLDC you could achieve this by lower the commutation threshold voltage to start the commutation slightly sooner as a means to compensate for the rotation of the rotor. Just using FOC already achieves this MUCH more accurately. And adding phase delay compensation makes it even more precise.