Control Systems Engineering - Masons Rule Help

[GreenPrint]

Homework Statement

I'm trying to find \frac{V_{Load}(s)}{I_{Dist}(s)} using Mason's rule. I was able to solve for \frac{V_{Load}}{I_{Cf}(S)} using Mason's rule but am not sure how to solve for \frac{V_{Load}(s)}{I_{Dist}(s)}.

http://imageshack.com/a/img31/4299/zr5.PNG

Homework Equations

The Attempt at a Solution

There's only one forward path, 1*\frac{1}{C_{f}s}*1. Am I supposed to consider the loops to the left of I_{Dist} to be non-touching loops? I've never solved a problem like this before were I'm asked to solve for the transfer function for a variable that's in the middle of a flow diagram and am not exactly sure. I'm also unsure if in the diagram that's a negative sign in front of I_{Dist}. Thanks for any help.

 

[donpacino]

As you stated there is only one forward path. That means that the gain will always be 1*1/CFS*1, as you already stated. It looks like there is a negative sign to me.

I don't want to just give you the answer, but you are VERY close.

 

[GreenPrint]

Is it really just -\frac{C_{f}s}{1 - C_{f}s}?

 

[donpacino]

well there is no loops in the circuits. so the gain would just be the forware gain.

so vload/-Idist=1/(CFS)

 

[GreenPrint]

So if I wanted positive Vload/Idist it would just be the opposite magnitude, -1/(CFS)?

 

[donpacino]

Yessir