At 20.50 2011.12.27, you wrote:
>At 11:35 AM 12/27/2011, Electron wrote:
>>At 18.51 2011.12.27, you wrote:
>> >
>> >Side question: are the diodes that make up the bridge rectifier fast
>> >or ultra-fast diodes?  If not, you will be seeing significant losses
>> >from those diodes.
>>
>>No they ain't but now after Your post they will be. :D
>>
>>If it matters: max switching frequency is about only 1000Hz though.
>>
>>By the way, when are fast recovery diodes NOT necessary, talking=20
>>about SMPS? Is there any situation ever when they can be safely avoided?
>
>I use fast diodes anytime I'm switching significantly faster than=20
>line frequency (60Hz *2 in my case).  I'm pretty sure that reverse=20
>recovery currents will start to become a measurable problem at 1 kHz.
>
>The more important factor is the rise time of your spike, as opposed=20
>to the actual switching frequency.
>
>The easy way to see if there is a difference is to actually try=20
>it.  Note - you may see your ringing problem actually get worse when=20
>you change to fast diodes.  However, I don't think that the ringing=20
>is a problem unless it becomes an EMI issue.

I will definitely try. Where should I see the improvements, at zero crossin=
g?

Just a thought: if ultrafast diodes are used because of their short reverse
recovery time (not for the fast forward recovery time) then a boost convert=
er
used in discontinuos mode should not benefit from it, or would it?

With kind regards,
Mario


>
>dwayne
>
>--=20
>Dwayne Reid   <dwayner@planet.eon.net>
>Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
>(780) 489-3199 voice          (780) 487-6397 fax
>www.trinity-electronics.com
>Custom Electronics Design and Manufacturing
>
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