Blog for students taking ECEN5817 Resonant and Soft Switching Techniques in Power Electronics, ECEE Department, University of Colorado at Boulder, Spring 2012
Friday, February 5, 2010
Problem 19.9
Can someone help me compare the Voc value for part A. I used Voc=(4*Vg/pi)*n*||H_inf(s)|| and got Voc=138V. This value seems too big for Vg=12V. Maybe my formula for Voc is wrong! Anybody with the same result?
I am having some doubts about my value of Isc. I get Isc =6uA. The way I did it was to find mag(Zo_0) and then use Isc = Voc/(n*mag(Zo_0). I get Zo_0 as 3.36M!!!
Also, I think wo and woo are independent of N. If you transform the load to the primary side (R/N^2)....this variable gets shorted and opened....so you just get what you calculated in the other problem. Does this seem right?
Yusuf, What are you calling Z_o0 in your formula? I think there is a Z_o0p found with the shorted input voltage for the primary side of the transformer that needs to be reflected to the secondary to find Z_o0=n^2 Z_o0p.
I guess I don't know what you mean by "reflect the short to the primary" since the only short should be on the input voltage on the primary.
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6 comments:
19.9a
Voc(peak)=154V
Your formula is correct.
H_inf(s)=sLp/(s(Ls+Lp)+1/(sC))
I am having some doubts about my value of Isc. I get Isc =6uA. The way I did it was to find
mag(Zo_0) and then use Isc = Voc/(n*mag(Zo_0).
I get Zo_0 as 3.36M!!!
Zoo = (Xp*Xs)/(Xp+Xs) = 3.2345 (on primary side)
Voc/Zoo = 154/3.2345/(1/N)^2 = 0.85A
Note: R1/R2 = (N1/N2)^2
Vojkan, do you agree?
Also, I think wo and woo are independent of N. If you transform the load to the primary side (R/N^2)....this variable gets shorted and opened....so you just get what you calculated in the other problem. Does this seem right?
I agree
Shouldn't it be OK to also reflect the short to the primary. In that case we get
nIsc=Voc/mag(Zo_0) giving the Isc formula I mentioned above.
Yusuf,
What are you calling Z_o0 in your formula? I think there is a Z_o0p found with the shorted input voltage for the primary side of the transformer that needs to be reflected to the secondary to find Z_o0=n^2 Z_o0p.
I guess I don't know what you mean by "reflect the short to the primary" since the only short should be on the input voltage on the primary.
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