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TMS320F28069M: Reverse issues

Robin Maubert
Intellectual 845 points
Part Number: TMS320F28069M


Hello TI support,

We are facing issues with reverse phases with a plane motor driving a propeller.

Main issue is not clear. Original topic is the https://e2e.ti.com/support/microcontrollers/c2000/f/171/p/779560/2921477#2921477

So my questions are : 

1. (replying on old 8th point) : You mentionned tu ose only the instaSPIN-FOC API instead of instaSPIN-MOTION if we do not care about the motion profile. Do you have any example or lab to refer ? What will be the advantage to use only the FOC part and not the MOTION ?

2. The main issue during reverse (mainly with wind so an unknown and variating torque applied on the rotor during the low RPM phase of the reverse) is not understood yet. How can we move froward with this hot question ? It is critical for us.

Thanks for the help,

Robin

  • 0
    TI__Genius 17175 points
    Are you using a position sensor? For the drive in question, what is the goal? For precise motion with position feedback, MOTION is the applicable algorithm as it provides a position loops. If you are interested in just torque or speed control, FOC is the solution I would recommend. MOTION is an additional set of S-T curves that are used for motion profiles, among other things. These are generally intended for use for drives that have position feedback, for something like a gimbal for instance

    Sean
  • 0 in reply to Sean Bigley
    Intellectual 845 points

    Hello,

    No we are not using a position sensor. For the drive, we want to drive a brushless motor (Axi 2808-20 V2) with a propeller (9x6) attached on the rotor with rubbers (so relative movement between the propeller and the reotor is possible) on a fixed wing plane. The most difficult thing is to achieve reverse (spin from positive to negative RPM) with an unknown wind applying an unknown and unstable torque on the propeller. Yes, it seems we are just interested into a speed and torque control. To give an idea, the RPM goal is always moving and updated at a rate between 50 and 200Hz.

    Robin

  • 0 in reply to Robin Maubert
    TI__Guru** 116120 points
    1. You may refer to lab5d or lab5e if you only need to implement velocity control based on instaSPIN-motion, you can change the reference speed at any timer per your requirement, but you can't change the acceleration that will be set by the motion speed controller. That's why we recommend instaSPIN-FOC for your case.
    2. For instaSPIN-motion, it's better to know the inertia and fraction of the system to get a good control performance, but it seems like the inertia and fraction will change as the motor speed. For a startup process, you should use a different gain or bandwidth, a precise Rs and ADC current&voltage offset will help improve startup performance also.
  • 0 in reply to Yanming Luo
    Intellectual 845 points
    Hi Yanming,
    Ok thanks for the reply and explanations.
    Robin