Tuesday, April 5, 2011

HW9 P1 - Voltage Loop Gain

For HW9 P1a, I was using figure 12.25a of the text as a guide, and as such I was able to get an equation for Gvc based on eqn 12.73. However, the voltage loop gain using this model would incorporate Fv as a multiplier (Tv = Gc(s) * Fv * Gvd(s)), and since Fv = 0 in model 4, I am inclined to think maybe I need to change the model in 12.25a to compensate for model 4 in some way. Could anyone give me a hint here?
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5 comments:

  1. Nitish AgrawalApril 6, 2011 at 9:45 AM

    Hi Audrey,

    I would use fig. 12.26 as a guide and eqn. 12.88 gives an expression for Gvc in terms of Gvd and Gid. Gvd is obtained from eqn. 12.81 and Gid from eqn. 12.84. Substitute Fv=0 and proceed.

    Nitish

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  2. AudreyApril 6, 2011 at 8:10 PM

    Thanks for the response Nitish. I tried using these other diagrams and equations, and I got the same result with the same question. In diagram 12.26, Fv is in the only path fed by v_hat. If Fv=0, wouldn't that imply the voltage loop gain is also zero, or are there other feedback paths not being represented in the diagram?

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  3. wrichApril 6, 2011 at 9:12 PM

    I'm at the same point. In figure 12.26 Fv is in the voltage loop so it appears that Tv=0. Perhaps the approach is to move forward utilizing the equations of table 12.3 and set Fv=0. But then how do you account or the compensator in those equations?

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  4. KYiApril 7, 2011 at 1:05 AM

    Fv=0. So you can ignore the Fv loop in fig 12.26. Then the loop can be closed as:
    ic-->v-->compensator-->vc-->ic

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  5. KYiApril 7, 2011 at 1:06 AM

    I meant fig 12.24

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