# Power electronic converter duty ratio

Discussion in 'General Electronics Chat' started by Johnjacob1992, Apr 28, 2015.

1. ### Johnjacob1992 Thread Starter New Member

Feb 27, 2015
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I have read from several different sources that the duty ratio for a Cuk converter is
(Vo/Vin)=(-D/(1-D)

but several other sources say its:
(Vo/Vin)=(D/(1-D)

which is the correct one...i'm tad bit confused..

2. ### Hypatia's Protege Distinguished Member

Mar 1, 2015
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Short answer: The former ((i.e. -D/[1-D]) is correct (from a 'positive' perspective)...

Note that Ćuk conversion schemes are, in essence, a variant of buck/boost topology (q.v.) hence the similar operation/performance thereof...

Best regards
HP

3. ### Johnjacob1992 Thread Starter New Member

Feb 27, 2015
7
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This is a snippet from the power electronics book from mohan and undeland, they say otherwise...
furthermore, I did some simulation and I got results which say (Vo/Vin)=(D/(1-D) is correct

Nov 30, 2010
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5. ### Johnjacob1992 Thread Starter New Member

Feb 27, 2015
7
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just to make sure....

6. ### #12 Expert

Nov 30, 2010
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The first responder did not accomplish that. Maybe some other people will answer and you can arrive at a two out of three or a three out of five consensus.

Feb 27, 2015
7
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yeap

8. ### Hypatia's Protege Distinguished Member

Mar 1, 2015
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The sign on the duty cycle is a matter of convention (specifically "truth" in the logical sense) - I stand by my reply -- On the other hand, if your perspective works for you, fair enough! -- 'tho I daresay insistence upon counter-conventionalism seems an unnecessary obstruction to communication...

Sincerely best regards
HP

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9. ### Johnjacob1992 Thread Starter New Member

Feb 27, 2015
7
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Thanks for the reply HP, I was just a bit puzzled as to why different folks used different signs. It makes sense now...Thank you