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Original question:

CCS/TIDM-BLPFC: BLPFCv 1.0

CCS/TIDM-BLPFC: BLPFC: some data in the code is doubtful

user6334344
Prodigy 30 points
Part Number: TIDM-BLPFC

Tool/software: Code Composer Studio

1 .Why is the effective value of module PFC_InvRmsSqr multiplied by VminOverVmax1？Why does traditional A find effective value without this ratio?
2 . What does VmaxOverVmin1 in module PFC_BL_ICMD stand for？
3 . What does data VoutMaxOverVinMax1 stand for(in PFC_BL_ICMD)?

  • 0
    TI__Genius 11935 points

    1. This is for scaling the signal appropriately. This is explained in TI appnote spra902a, section 3.2.2

    Now, in calculating the inverse, Vinv, of Vdc1, i.e., Vinv=1/Vdc1, it is clear that Vinv is maximum when
    Vdc1 is minimum and vice versa. Therefore, to achieve better accuracy in the fixed-point representation of
    Vinv, it is necessary to represent this with a pu value normalized with respect to its own maximum value.
    For a sine-wave input voltage, the minimum value of Vdc is 2Vmin/p, where, the minimum amplitude,
    Vmin, of the rectified input voltage is selected based on the input operating voltage range of the PFC
    converter. For example, to operate the PFC converter with a low line voltage of 90Vrms, the chosen value
    of Vmin should be less than or equal to 127V. With the selected value of Vmin, the maximum value of
    Vinv is (p/2Vmin) and the corresponding pu value of Vinv with respect to its own maximum value is:
    Once Vinv is calculated with the maximum accuracy, the feed-forward component C can be calculated
    with the same accuracy as,

    2,3. This is also for signal scaling. It is explained in the appnote.

    Shamim

  • 0 in reply to Shamim Choudhury
    Prodigy 30 points

    Hi  Shamim,

        Thank you for answering my question. There are other questions. Must the scaling factor Vmin / Vmax be a fixed value in a circuit? In the manual, I see that the range of this zoom ratio is [0, 8], is it reasonable as long as it is within this range? Can I adjust it according to the actual situation of the circuit?

        Thanks!
        

  • 0 in reply to user6334344
    TI__Genius 11935 points

     Vmax is fixed in any design. But Vmin is something you can select and change easily. It could be 65V, 70V, 80V whatever you want to choose and then use that to do you scaling/normalization. Because of this, yes, you can specify a range for the ratio.

    Shamim