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Original question:

TMS320F28027F: would it be possible to run FOC without voltage sampling (Va,Vb,Vc)?

TMS320F28027F: Smooth rotation in Scaler(V/F) control Mode

Dave Hunson
Expert 1760 points

Part Number: TMS320F28027F

Hi everyone!
Good day!

Please bear with my question, and I would be happy if you could kindly find a solution for my problem.

I have been using InstaSPIN-FOC for ACIM for more than 11 years. Using FOC control mode in most cases is impossible because most of the time the motor is installed with a load, and we are not able to detach it from the load to identify the ACIM. It gets even harder when we need to lock the rotor!

So we resorted to using V/F control instead, but sadly V/F control (scalar control), due to dead time (which is typically 2 µs or more) causes dead time distortion that makes torque ripple in the rotor!

TI offers (DT compensation) this code:
value += _IQmpy(_IQsat(Current_neg, Ith, -Ith), Kdtc);
to cover this problem, but I think it is not a perfect solution.

What we need is current loop regulation like InstaSPIN Labs Lab01c (Closed current loop for signal chain verification) combined with V/F.

My question is: Is there any code to achieve smooth rotation (without torque ripple in the rotor) while using scalar (V/F) control?

Thanks for your attention.

Dave

  • 0
    TI__Expert 7835 points

    Hi Dave,

    Please help me understand what do you want to use as your reference and angle information for current regulation loop. For V/F control of ACIM, we normally do not have angle information, and also do not have a reference current to regulate the current to.

    To solve nonlinearity caused by DT, you can normally use better nonlinear model of the power switch device you are using, and then implement the DT compensation accordingly, with a nonlinear function. There are many papers around this. 

    Han