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Electrical Engineering/Question on kickback voltage on coil

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Question
Hello,
In this buck regulator circuit:
http://i.imgur.com/uFg2qKF.png
When current to primary coil is cutoff, kickback will develop on primary coil with polarity (+) at bottom. So direction of D1 is correct for this kickback voltage.
But on the secondary side, when current that was coming from the dot was cutoff, kickback would develop with polarity (+) on top (??)(to maintain the original direction of current). If that is the case D2 would be no help to absorb the kickback. Is there something I miss in this observation ?
Thank you!

Answer
D2 charges up the output cap whilst conducting.  D3 keeps the output cap from discharging whilst D2 is non-conducting and conducts forward as well to keep the charge at the output cap.

A full explanation of the buck converter is found at:

http://en.wikipedia.org/wiki/Buck_converter

Hope this helps.  

Electrical Engineering

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