--- Olin Lathrop <olin_piclist@embedinc.com> wrote:

> That's quite long compared to the electrical and thermal time
> constants in the system, so must be dealt with as steady state from 
> the design point of view.
> 
Yes this dawned on me after a while (put bit if hysterical laughter at
this point).
> 90% is very aggresive.  I'm assuming the outputs need to be isolated,
> so this will require a transformer.  For each output, there are at 

 Well it will require a transformer irreguardless actually.  The
difficulty of using a bucking system instead of a forward system and
the efficiencies.. well it's just not going to happen is it?  I shudder
everytime I look at PC powersupplies :)

> least two switching supplies and a transformer in series (PFC is 
> essentially a switching power supply).  To get 90% overall would 

I'm very familiar with PFC, I researched and experimented with it 17
years ago (college students are crazy I'll admit it).  My main concerns
are 1) killing the switching elements, 2) safety, 3) weight reduction,
4) efficiency.  A bucking regulator is simple inadequate by any form of
measurement.  It needs to be line isolated for the obvious reason it
has to work with a lot of DC electronics (but not power them) contacts
and sensors.

> require each of these to average 96.6% efficient or higher.  That is 
> probably not possible with a realistic budget.
> 
If you don't try you won't get there.  Even if it isn't realistic from
first appearances. I'm just curious what people have done and the big
sources of difficulties with something like this.  I don't expect
someone to say "Well just use this!" In fact I would be really really
suspicious if someone said that. :)

> What you are trying to do is NOT trivial.  Your best bet is to try

Hmmm never said it was, it's also quite dangerous if done improperly.

> and find something close enough off the shelf.  If that doesn't work,

> you > might want our professional services.  Please contact me off 
> list if you're interested.
> My contact info is:
> 
>   Olin Lathrop
>   Embed Inc
>   410 Great Road
>   Littleton, MA  01460
>   (978) 742-9014
>   olin@embedinc.com

I appreicate your contact information I will look you up when I'm done
getting a theoretical design that might work.  It's a pretty scarey bit
of work. Actually very scarey considering all the different possible
scenarios that could happen.

Thanks for your input Olin!

Stephen


		
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