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Teknic motor in DRV8301-LS31-KIT

Yu Zou
Expert 1190 points
Other Parts Discussed in Thread: INSTASPIN-BLDC

It is said the provided BLDC is 6k rpm. Does it mean 12 poles then?

The default number of poles in "Setting" of GUI is 8 poles and I found I cannot change it to 12! Why is this?

Also, under "Duty Cycle" mode and no load, I tried 90%, the speed reach 4k rpm and the current is jumping up and down (the motor is getting hot too, of course.)

  • 0
    TI__Guru** 119590 points

    The Teknic motor is 8 poles. Why do you think 6k RPM relates to 12 poles?

    here is the datasheet

    http://www.teknic.com/files/product_info/N23_Industrial_Grade_Motors_v5.0.pdf

    I'm not sure why that GUI won't let you change the poles, some do. Hercules group probably didn't want you changing it with the motor provided.

    You didn't reach 6k RPM because you don't have enough voltage. These motors are rated for like 50-60V. A 24V power supply won't allow them to go fast enough.

    Regarding current jumping, InstaSPIN-BLDC initially has no current control, it is just to give you an easy way to "tune" your commutation.  You then have to tun the current and speed if you want yourself.

    There is an InstaSPIN-BLDC GUI lab for Piccolo that you can follow to learn the general concept.

     

     

  • 0 in reply to ChrisClearman
    Expert 1190 points

    Very helpful, thanks a lot. Two more questions here:

    1. Could I feed PVDD and GND with my own high voltage power supply? Do I need to limit certain level of the supply current then?

    2. I'm still confused that why 6k related to 8 poles? What's the formula for this then?

  • 0 in reply to Yu Zou
    TI__Guru** 119590 points

    1. sure. from a HW perspective you need to limit to 60V.  For InstaSPIN-BLDC GUI the SW should be fine, it shouldn't care....I think. There may be an overvoltage check in the GUI....there was one in one of the GUIs but not in others. Sorry, I can't recall.

    2. RPM = Hz * 120 / poles.

    so for this motor 6000 = Hz * 120 / 8 = 400 Hz, but only at the rated voltage.  I'm trying to get the link from Teknic which shows the speed / torque/ voltage curves.

     

  • 0 in reply to ChrisClearman
    Expert 1190 points

    Chris,

    I'm still confusing how to know the motor's pole at beginning. I mean w/o knowing 400Hz, how could I know the # of poles? 

    Previously, I used 60Hz to do the cal. and the resulted rpm does not make sense at all. But, how to know what Hz I should use then? I mean w. 6k rpm, we should know the freq 1st and then cal. the # of poles, right?

  • 0 in reply to Yu Zou
    TI__Guru** 119590 points

    you get the # of motor poles from

    1. the manufacturer / datasheet or

    2. you can take a guess, and if InstaSPIN-FOC IDs reasonably correctly you can set 60 RPM and see if you are getting 1 revolution per second. If not, you need to adjust the pole count.

    3. on some motors you may be able to turn the rotor and count the poles. This isn't very reliable with most motors though

  • 0 in reply to ChrisClearman
    Expert 1190 points

    This makes sense, thanks a lot!