Buck converter output voltage ripple

Discussion in 'Homework Help' started by notoriusjt2, Oct 21, 2010.

Feb 4, 2010
209
0

deltaVo/Vo = (1 - D)/(8 LCf^2) = (1 - 0.6)/(8 (10uH) (50uF) (150000)^2)

= 0.4/90 = 0.0044v

the book says "It is also useful to express the ripple as a fraction of the output voltage"

so then the answer would be 0.44% but not 0.44v. is this a typo or did i do something wrong?

2. t_n_k AAC Fanatic!

Mar 6, 2009
5,448
782
You should check your calculations more carefully

ΔVo/Vo=.00444

Vo=D*Vs=0.6*15=9V

ΔVo=0.00444*9=0.04V

Feb 4, 2010
209
0
do you have all these formulas memorized or are you looking this up?

4. t_n_k AAC Fanatic!

Mar 6, 2009
5,448
782
I'm mainly using the formulas you are posting - for this case in particular. Presumably these are what you have been given in class. Best to stick with the methods your teachers / text books are using.

Since you are struggling somewhat with this work it might be worth doing some simulations - if you have some simulation software on your PC or you could download one of the freebies. Doing some simulations may help in visualizing what is actually happening with the various voltage and currents in the circuits in relation to time.

I've never found just plugging values into formulas particularly helpful without first having some clearer idea of what is physically happening. Where possible I like to trust what I use through confirmation by some alternate means - particularly in more complex circuits.