# Power electronic converter duty ratio

#### Johnjacob1992

Joined Feb 27, 2015
7
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..

#### Hypatia's Protege

Joined Mar 1, 2015
3,208
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

#### Johnjacob1992

Joined Feb 27, 2015
7
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

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

#### #12

Joined Nov 30, 2010
18,190
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
If you already know the answer, why did you ask?

#### Johnjacob1992

Joined Feb 27, 2015
7
If you already know the answer, why did you ask?
just to make sure....

#### #12

Joined Nov 30, 2010
18,190
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.

#### Johnjacob1992

Joined Feb 27, 2015
7
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.
yeap

#### Hypatia's Protege

Joined Mar 1, 2015
3,208
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
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