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Original question:

question for technical support

TMS320F28035: DQ Decoupling for PMSM motor

Patel
Intellectual 330 points
Part Number: TMS320F28035

Hi,

I was reading the article (

https://e2e.ti.com/blogs_/b/industrial_strength/archive/2013/04/30/teaching-your-pi-controller-to-behave-part-ix#pi321855=1

) and it describes the decoupling in very detail. I am using Enhansed Sensorless application note. Now the question is how do I get per units values for all the variables? 

I have PU voltage and PU Current with regards to my ADC max measurements. How do I calculate PU Ld, PU Lq, PU back-emf constant, PU omega? 

  • 0
    TI__Guru** 114200 points

    Only the current, voltage, and frequency need to be converted to PU format. The motor parameters are not used in the control code directly as the article you mentioned, which must be calculated with the sampling period. You might refer to the SMO/eSMO example code that uses the Rs and Ls value.

  • 0 in reply to Yanming Luo
    Intellectual 330 points

    Vd = -wLq*Iq;

    Here w is in PU and IQ24, Iq is in PU  + Iq24. Should I use Lq in Iq24?  If I do so term will be so big and will screwup my PI outs.

    Please correct me If I am wrong.

  • 0 in reply to Patel
    TI__Guru** 114200 points

    As mentioned above, you need to convert these equations in a discrete form that includes the motor electrical time constant and the sample time, and then uses the PU with IQ format. You might find such content in motor control textbooks. It's difficult to explain it in a short text on E2E.

    Recommend you use the latest C2000 devices like F2804x, F2838x... that supports floating-point, so you can use the mathematical formula with SI format to design your code.