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TMS320F28069M: RsOnline diverges

Robin Maubert
Intellectual 845 points
Part Number: TMS320F28069M

Hello TI community,

As mentionned in the http://e2e.ti.com/support/microcontrollers/c2000/f/171/t/507801?RsOnline-oscillating#pi320995=2, we are facing a similar issue. 

RsOnline estimation works perfectly most of the time, but sometimes it diverges : it reaches 200% of the expected value and leads to a bad control...

We tried to change SlowRotatingAngle frequency and RsOnline filter parameters (keeping the ratio between them as in the datasheet) but it is very painful.

Can we get some help ?

Can we get some details about the feature and the source code for this feature ?

Thanks,

Robin

  • 0
    TI__Guru** 109730 points
    Please only enable Rsonline during the motor is running with a constant load and the torque current is much less than the maximum current. It can't work well under heavy load when the torque current is close to the maximum current, and you must inject a higher current if the motor is running without load.

    Please refer to Chapter of instaSPIN user's guide (SPRUHJ1G) to find more information about RsOnline that are all contents we can provide.
  • 0 in reply to Yanming Luo
    Intellectual 845 points

    Hello Yanming,

    Thanks for the reply.

    1) We worked a lot on the RsOnline filter and found that RsOnline returned by the estimator function is close to the voltage filter output over the current filter output, can you confirm ? Can you precise also the input and the units of the outputs of the filter please ?

    2) We found that there is something which discards or smooths the returned value by the estimator, can you add some details ? Our issue is still a divergence with a slow rotating angle at 2s period. Is there a rule concerning the SlowRotatingAngle frequency and the filter parameters to respect ?

    3) We also found that when we set RsOnlineFilter parameters, filter seems to reset, can you detail ?

    4) In the datasheet, §15.8.3, some functions are mentionned to adjust delta but are not available in the TMS320F28069M, is it normal ?

    Thanks for your help,

    Robin

  • 0 in reply to Robin Maubert
    TI__Guru** 109730 points
    1. The detailed information can be found in Chapter 15.8.4. The RsOnline will be derived for the current and voltage filter output. The inputs are the feedback current and voltage from the outout of clark transfrom, the real unit should be V and A, but uses per-unit for caculation in the algorithm.
    2. That depends on the temperature dynamics of the motor, default parameters should be enough for most motor and system.
    3. The chapter 15.8.4 should have all the information we can provide, that should be enough, you just need to change the cut off frequency of the filter accronding to the temperature dynamics of the motor.
    4. Right, both functions are not disclosed, you can't change the delta value of RsOnline.

    Btw, we don't recommend that you should use RsOnline always, especially the power supply is battery, you might enable RsOnline after some interval of time when the load or speed doesn't have greatly change.
  • 0 in reply to Yanming Luo
    TI__Guru** 109730 points
    So you may try to increase the injection current (gMotorVars.RsOnLineCurrent), and tune the filter parameters that should improve the stability.