Maximum power transfer question

Discussion in 'Homework Help' started by electroboc, Nov 24, 2011.

  1. electroboc

    Thread Starter New Member

    Nov 17, 2011
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    Any body able to give me a hand with this question?

    A. The value of R and X that will result in maximum power to be transfered across terminals A and B?

    B. The value of Maximum power?

    can anyone give me any direction??

    Many thanks
     
  2. jimkeith

    Active Member

    Oct 26, 2011
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    99
    My guess is that if you isolate the load and determine the thevenin Zequiv in rectangular form, you will have the max transfer of power when R and X are equal to these values as L and C will series resonate.

    Happy Thanksgiving Day, if you live in the US
     
    Last edited: Nov 24, 2011
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Another perspective:

    The load would need to be the complex conjugate of Zequiv.

    So if Zequiv=A+jB then the required load for MPT would be Zload=A-jB.
     
  4. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
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    I believe maximum power transfer always occurs when source impedance matches load impedance. That's why antennas use impedance matching transformers to match the 75 Ohm transmission line.
     
  5. Yako

    New Member

    Nov 24, 2011
    245
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    ^ Yeah that's right

    XL = XC = resonance / max amplitude

    Tuning for max amplitude.
     
  6. Yako

    New Member

    Nov 24, 2011
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    XC = 1 / 2 pi (fc)

    I have forgotten XL equation.
     
  7. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    That's true when the load and source impedances are purely resistive.

    When there are complex reactive terms involved then the MPT occurs when you have complex conjugate matching between the source and load.
     
  8. electroboc

    Thread Starter New Member

    Nov 17, 2011
    4
    0
    one question i have, i have removed the load and worked out the short circuit voltage and have 50 volts.

    when you work out the impedance i am struggling on whether just product over sum

    5x5 over 5+5 or do i need to incorporate the j10ohm as well due to the phase angle?
     
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