Velocity Reviews > Convert ATX PSU to run on 192V DC rail

# Convert ATX PSU to run on 192V DC rail

VWWall
Guest
Posts: n/a

 06-11-2004
VWWall wrote:
> WiseIndian wrote:
>
>> thanks for your inputs guys.
>>
>>
>>> Normal 200V AC input?
>>> where are you?
>>> Do you perhaps mean 220/240?

>>
>>
>> yes i did mean 220/240V
>>
>>
>>> however the power savings would probably be too small to bother with
>>> unless you happen to be running a pretty niced sized "server farm"

>>
>>
>> yes it is a 35 comp plus gaming center with the monitors on a seperate
>> offline inverter line. the online UPS has a 16 battery bank and seems
>> to
>> working at 65-70% overall efficiancy, since we are running 24 hrs a
>> day
>> the saving potential is huge.
>>
>>
>>> A SMPS peak charges the input caps to 1.414 times the input voltage.

>>
>>
>> So, >200VAC would result in about 283VDC on the caps.
>> true but considering that we run on clean battery power is it
>> necessary to
>> have them caps fully charged ?

>
>
> The DC input to the switching circuitry has to be within design limits.
> For 90-140 V this is 255-396 V DC. Your 292 V DC is far too low.
>

This, obviously, should say: Your *192 V DC* is far too low. Put
another way, 192 V DC at the input to the switching circuits would
correspond to an input of 72/136 V AC, below the low limit design of
90/180 V AC. The PSU would not even attempt to start at this level.

Virg Wall
--
A foolish consistency is the
hobgoblin of little minds,........
Ralph Waldo Emerson
(Microsoft programmer's manual.)

kony
Guest
Posts: n/a

 06-11-2004
On Fri, 11 Jun 2004 04:53:15 GMT, VWWall <(E-Mail Removed)> wrote:

>> There is no guarantee that a 120VAC supply will have a voltage doubler. For
>> the same power (~300W), I suspect a 170V input supply is cheaper to build
>> than a 350 V supply. For the voltage doubler, you about doubled the price of
>> the filter caps, used more expensive transistors, and transformers with more
>> turns. If you make a million power supplies, and save a dollar on each one,
>> you start approaching serious money.

>
>I've never seen one without, have you? Actually the cost of switching
>transistors is much more dependant on their current capacity than their
>voltage ratings. Also, with a fixed "on" voltage drop, the heat will
>increase with the current being passed, requiring larger heat sinks, and
>resulting in lowered efficency.
>
>For a 240 V DC input , there is no choice but to use the full peak
>rectified DC! Check the price of filter caps. You'll find no where
>near a double price! The output transformer primary turns are double,
>at the higher voltage, but with half the wire size . The output
>windings have fewer turns at the same wire size.
>
>It may be serendipity, but the voltage doubling power supply represents
>about the most economical design possible. When you consider that a
>single SPST switch makes it a 115/130 V unit, you can see why the design
> is so universal!
>
>Virg Wall

IIRC, most if not all of the Active PFC units don't have a voltage
doubler, if we can take it for grated that having only one HV cap on the
HV side is evidence of a non-doubled design.

However, I"m not so sure of the viability of setting up this multi-dozen
system arcade as OP wants... It would require replacing all the power
supplies with, at a minimum, signficantly higher than average priced
units, then a customized power grid to deliver the 192V DC... it is not
going to meet code to use the existing AC wiring and outlets to deliver
192V DC, so less common, more expensive couplers will be needed at
multiple points.

Once one starts adding up the costs then the difference in energy
consumption, energy cost, may not be recouped within projected lifespan of
these gaming systems. If power generation is the issue then perhaps a
different UPS, modification to existing UPS, or alternate energy source
would be beneficial.

VWWall
Guest
Posts: n/a

 06-11-2004
Robert Baer wrote:

> VWWall wrote:
>
>>WiseIndian wrote:
>>
>>
>>>I am wondering if a normal 200V AC input ATX PSU can be converted to
>>>run on a 192V DC Rail, considering the enormous electricity my 16
>>>battery online UPS is using it must be more efficient running the
>>>computers directly an the 192V DC rail and running the monitors on a
>>>seperate offline inverter line . I am not very familiar with how the
>>>ATX PSU works , but it understand the first stage involves converting
>>>the 200V AC Input to 200V rectified DC. anyone guide me if it is
>>>possible?

>>
>>Where do you get the value for "the 192V DC rail"? 16 12V, (6 cell),
>>batteries in series will give this value. Is it then rectified and
>>converted to 120/240 V AC? This must be a very large UPS!

This, of course should read: "Is it then applied to an invertor and..."
>>
>>The ATX PSU input is nominally 240V AC, which when rectified results in:
>>240 x 1.44 = ~345V DC. (For 120V AC input a doubler rectifier circuit

Typo: (240 x 1.414 = ~340 V DC)

>>is used, resulting in about the same DC voltage.) This DC voltage is
>>supplied to the switching transistors, resulting in an output to the
>>final transformer at an equivalent of 40-60 K Hz. This high frequency
>>allows for the use of a much smaller transformer.
>>
>>One could design a PSU to run from 192V DC with a somewhat lower
>>efficiency, but this would be a completely non-standard unit.

> *RECTIFY*???? a DC voltage??? NUTS! cannot be done!

Webster's Dictionary: rectify 1) To make or set right
4) To make an alternating current unidirectional.

Sorry, it was getting late!

Virg Wall
--
A foolish consistency is the
hobgoblin of little minds,........
Ralph Waldo Emerson
(Microsoft programmer's manual.)

VWWall
Guest
Posts: n/a

 06-11-2004
kony wrote:
> On Fri, 11 Jun 2004 04:53:15 GMT, VWWall <(E-Mail Removed)> wrote:

>>It may be serendipity, but the voltage doubling power supply represents
>>about the most economical design possible. When you consider that a
>>single SPST switch makes it a 115/130 V unit, you can see why the design
>> is so universal!

> IIRC, most if not all of the Active PFC units don't have a voltage
> doubler, if we can take it for grated that having only one HV cap on the
> HV side is evidence of a non-doubled design.

I'm curious. I always thought they used something like "steering"
diodes to select the voltage range. I can't imagine a switching circuit
that would work over a range of 127-340 V DC (90-240 V AC input). That
would imply a current range of 2.67/1! What is the voltage at the HV
side? And how does it get there? Anybody know?

Schematics for any ATX supplies are scarce. Anybody have any sources?

Virg Wall, K6EVE
--
A foolish consistency is the
hobgoblin of little minds,........
Ralph Waldo Emerson
(Microsoft programmer's manual.)

kony
Guest
Posts: n/a

 06-11-2004
On Fri, 11 Jun 2004 15:20:37 GMT, VWWall <(E-Mail Removed)> wrote:

>kony wrote:
>> On Fri, 11 Jun 2004 04:53:15 GMT, VWWall <(E-Mail Removed)> wrote:

>
>>>It may be serendipity, but the voltage doubling power supply represents
>>>about the most economical design possible. When you consider that a
>>>single SPST switch makes it a 115/130 V unit, you can see why the design
>>> is so universal!

>
>> IIRC, most if not all of the Active PFC units don't have a voltage
>> doubler, if we can take it for grated that having only one HV cap on the
>> HV side is evidence of a non-doubled design.

>
>I'm curious. I always thought they used something like "steering"
>diodes to select the voltage range. I can't imagine a switching circuit
>that would work over a range of 127-340 V DC (90-240 V AC input). That
>would imply a current range of 2.67/1! What is the voltage at the HV
>side? And how does it get there? Anybody know?
>
>Schematics for any ATX supplies are scarce. Anybody have any sources?
>
>Virg Wall, K6EVE

I have one, around here "somewhere", LOL...
Have been pretty busy these days but if I get a chance and can find it,
I'll take a look at it. Well, I can "look" at it now since I have a
picture handy but that's not quite enough.

http://69.36.189.159/usr_1034/liteon_side.jpg

Ryan
Guest
Posts: n/a

 06-11-2004
http://www.velocityreviews.com/forums/(E-Mail Removed) (WiseIndian) wrote in message news:<(E-Mail Removed). com>...
> I am wondering if a normal 200V AC input ATX PSU can be converted to
> run on a 192V DC Rail, considering the enormous electricity my 16
> battery online UPS is using it must be more efficient running the
> computers directly an the 192V DC rail and running the monitors on a
> seperate offline inverter line . I am not very familiar with how the
> ATX PSU works , but it understand the first stage involves converting
> the 200V AC Input to 200V rectified DC. anyone guide me if it is
> possible?

What you want is a "full input range" ATX supply. Do not get an
"auto-switch" supply as these have voltage doublers that won't work
with DC.

I am willing to bet a full input range supply will work just fine on
DC without modification, and most spec 90-264 VAC which is 127-373
VDC; indeed within your 192 VDC rail.

Ryan

N. Thornton
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Posts: n/a

 06-11-2004
"Tam/WB2TT" <t-tammaru@c0mca\$t.net> wrote in message news:<(E-Mail Removed)>...
> "N. Thornton" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) om...
> >
> > so youre saying more or less all universal supplies should work on 192

> IIUC.
> >
> > Regards, NT

>
> I am saying this is a marketing issue, not an engineering issue. Also, for
> multi voltage use, having to change a strap from bridge rectifier to voltage
> doubler is not the preferred way. Preferred by whom? depends on your
> management and marketing types.
>
> Tam

You still dont seem to addressing the simple question of whether a PC
PSU is likely to work on 192dc. Thats the q here, marketing has
nothing to do with that. Design optimisation is not marketing.

Regards, NT

Tam/WB2TT
Guest
Posts: n/a

 06-11-2004

"N. Thornton" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> "Tam/WB2TT" <t-tammaru@c0mca\$t.net> wrote in message

news:<(E-Mail Removed)>...
> > "N. Thornton" <(E-Mail Removed)> wrote in message
> > news:(E-Mail Removed) om...
> > >
> > > so youre saying more or less all universal supplies should work on 192

> > IIUC.
> > >
> > > Regards, NT

> >
> > I am saying this is a marketing issue, not an engineering issue. Also,

for
> > multi voltage use, having to change a strap from bridge rectifier to

voltage
> > doubler is not the preferred way. Preferred by whom? depends on your
> > management and marketing types.
> >
> > Tam

>
>
> You still dont seem to addressing the simple question of whether a PC
> PSU is likely to work on 192dc. Thats the q here, marketing has
> nothing to do with that. Design optimisation is not marketing.
>
> Regards, NT

Well, if you have a supply built for 95 -135 VAC operation that does not
use a voltage doubler it should work. 135 x SQRT(2) =190, close enough. Now
the question is does the supply need AC for other reasons. When the PC goes
into standby the fan stops; I don't know for a fact, but suspect the main
supply also might shut down. Where does the keep alive voltage come from?

Tam

ric
Guest
Posts: n/a

 06-12-2004
Tam/WB2TT wrote:

> Well, if you have a supply built for 95 -135 VAC operation that does not
> use a voltage doubler it should work. 135 x SQRT(2) =190, close enough. Now
> the question is does the supply need AC for other reasons. When the PC goes
> into standby the fan stops; I don't know for a fact, but suspect the main
> supply also might shut down. Where does the keep alive voltage come from?

Depends on the supply design. Some use a small bias transformer off of
the AC input, and some use a switching design off of the 300v buss.
Whether his 192VDC would support the latter is a good question. If his
supply used the former, he'd be SOL.

I'd use an AT rather than a ATX supply, if possible.

Robert Baer
Guest
Posts: n/a

 06-12-2004
Ryan wrote:
>
> (E-Mail Removed) (WiseIndian) wrote in message news:<(E-Mail Removed). com>...
> > I am wondering if a normal 200V AC input ATX PSU can be converted to
> > run on a 192V DC Rail, considering the enormous electricity my 16
> > battery online UPS is using it must be more efficient running the
> > computers directly an the 192V DC rail and running the monitors on a
> > seperate offline inverter line . I am not very familiar with how the
> > ATX PSU works , but it understand the first stage involves converting
> > the 200V AC Input to 200V rectified DC. anyone guide me if it is
> > possible?

>
> What you want is a "full input range" ATX supply. Do not get an
> "auto-switch" supply as these have voltage doublers that won't work
> with DC.
>
> I am willing to bet a full input range supply will work just fine on
> DC without modification, and most spec 90-264 VAC which is 127-373
> VDC; indeed within your 192 VDC rail.
>
> Ryan

Incorrect; any switcher will work from DC - by definition!
What do you think happens to the incoming AC?
It gets rectified, and due to a fairly large capacitor, gets turned
into.......
......
......
......
......
......DC!