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Do not understand Solution to this problem (AC Circuit Analysis)

  1. Sep 25, 2014 #1
    1. The problem statement, all variables and given/known data
    See The attached Images.

    2. The attempt at a solution

    The problem I am having with this is the following.

    I do not know where he is getting these equations from. We haven't done anything like this in class. Although he keeps mentioning skills we learned in previous courses, which I took at another institution so it wasn't all exactly the same.

    I see what looks like normalization constants from fourier analysis? (2/pi) And square roots of 2 (usually indicates RMS). But I do not know the logic behind the equation. Also, why is he using "X" to indicate resistance? Is it a reactance? I also don't know where he gets the expression for the phase "u."

    Sorry I know this might seem like a silly question but if anyone can help me out I would really appreciate it!
     

    Attached Files:

  2. jcsd
  3. Sep 26, 2014 #2

    rude man

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    X is the universal symbol of reactance: Z = R + jX. X = wL for inductor and -1/wC for capacitor. X is in Ohms.

    I can't make out the text in the 1st (your work) slide.
     
  4. Sep 26, 2014 #3

    NascentOxygen

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    Staff: Mentor

    It looks like this might be using design approximations used for inductive smoothing at the output of a bridge rectifier. The flattened current waveform suggests you can assume very effective smoothing. That constant current indicates why you can represent the load as a fixed voltage source: a steady current into a fixed load is just like a fixed voltage in opposition.

    The topic may be discussed in your textbook, otherwise search for worked examples online.
     
    Last edited: Sep 26, 2014
  5. Sep 26, 2014 #4

    NascentOxygen

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    The handwriting is very clear and easy to read on my tablet, anyway.
     
  6. Sep 26, 2014 #5

    NascentOxygen

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    Have you asked others in the class about these formulae? In any subject, your best resource is always other students in your class.
     
  7. Sep 26, 2014 #6

    rude man

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    So's mine. I was referring to the printed text.
     
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