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TIDA-010933: Questions about the sample code

Seamus Pu
Intellectual 830 points

Part Number: TIDA-010933

Tool/software:

Hi Expert,

I have some questions about the sample code of TIDA-010933:

1. uINV_DCAC_runISR1_lab3

Why does the final result output need to be *-1? So it feels like the output becomes the opposite?
In addition, what is the purpose of passing the DC voltage through the band rejection filter?

2. uINV_DCAC_runISR1_lab4

   uINV_DCAC_runISR1_lab5

Why do we need pr to control the 1st, 3rd, 5th, 7th and 9th harmonics?

3.  void computeDF22_NotchFltrCoeff(DCL_DF22 *v, float32_t Fs, float32_t notch_freq, float32_t c1, float32_t c2)

What do the c1 and c2 parameters of the band rejection filter represent?

4. Which method do we use for z conversion in the programming of pr controller and band rejection filter?

Best Regards,

Seamus

  • 0
    TI__Intellectual 2930 points

    Hi Seamus,
    Riccardo is responsible for DC/AC part and will answer you soon.

    Best regards, Seva. 

  • 0
    TI__Expert 3290 points

    Seamus,

    1. uINV_DCAC_runISR1_lab3 sign minus is there for stability of the voltage control loop. Notch filter is used because there will be 100 Hz harmonics on the DC link voltage measurement.

    2. when you use this controllers, you need to implement this for all the higher order harmonics. If the final design of another application is not critical with certain harmonics that harmonics controls can be removed too.

    3. C1 and C2 are damping factor for the denominator and numerator

    Hnf=(s^2+2*c2*wn*s+wn^2)/(s^2+2*c1*wn*s+wn^2)

    4: trapeizoid

    Thanks

    Best Regards

    Riccardo