No Fan, Sealed, 200 Watt, 110VAC -> 20VDC Power Supply

[TheRealMagicRat]

All,

Well, I have this idea for a patent ... but ... it requires a power supply ... and I can't find one that meets my needs.

I need to come up with the smallest, cheapest 110VAC -> 20VDC, 10AMP (or close to that) power converter (about 190 - 200 Watts), constant voltage.

Small means about 5" X 3" X 2".

Ideally, I would find some commercially available power supply for less than $100 a copy and adapt it ... but, no such luck.

I can't find one that size at any price.

There seems to be a barrier at about 120 Watts. This is due (I think) to the U/L certification requirement for 30 cfm air flow (fans) to get any more power than about 120 watts. So, things above 120Watts get a lot bigger (about twice as big in terms of form factor).

But, maybe ... hopefully ... I'm wrong about that.

I have two design ideas and the primary factor that differentiates the two is cost. A small $100 or less unit makes my desired plan the best option. If price is above $100 then I must go to the second option (which allows a bigger power supply but requires lots more cables and other manufucturing ... it's not as good a design ... but it will work).

I dunno.

So ... anybody think of anything??

 

[ScottyUK]

Check out Vicor's range:

http://www.vicr.com

http://www.vicorpower.com/documents/datasheets/ds_flatpac.pdf

http://www.vicorpower.com/documents/design_guides/vipac.pdf

There are modules in the latter link which look a close fit if you can get rid of the heat. You'll have to work out which modules make the best solution - the VC/VP-E and VC/VP-G configurations shown on page 16 (18th page in .pdf) are fairly close in size to your requirement.

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Sometimes I only open my mouth to swap feet...

 

[DaveScott]

What about the humble computer ATX PSU? Now they are available without fans. Trouble is, with +/- 12V, they doesn't match precisely, but they are cheap!

 

[itsmoked]

Naw his space constraints are insane.. It can probably be done but I bet it would be a full-on custom.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

Have a look at these.

http://www.xp-medical.com/index.php

I have been studying them for a compact application. The RCL175 is close, but not quite what you are after. Sometimes, it is better to adjust to the real world than trying to adjust the world to suit one's needs.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[MikeHalloran]

Your power supply spec is not complete yet. You need to decide how 'constant' a voltage you can tolerate, and how constant your demand is, and over what frequency range you define 'constant'.

E.g. if your load current is not always 10A, but could vary from 1..10A, would it be okay for the voltage to also vary from, say 20..16V?

E.g. would it be okay to have some ripple in the supply voltage, say 2V p-p @ 20kHz?

Since you appear to have decided on the envelope before anything else, you'll probably need a full custom supply, and simple switchers have a chance of squeezing what you want into your box.



Mike Halloran
Pembroke Pines, FL, USA

 

[CJCPE]

You are looking for a 200 W power supply in a 30 cu. in. package. I have a 65 W 18.5 V notebook computer power supply that is in an 8.7 cu. in. package. Three of those whould come pretty close.

 

[DaveScott]

Power adaptors as follows. None fit what you want. I think you might need to review some of your requirements.

Adjustable volts, 120W:

http://www.maplin.co.uk/module.aspx?TabID=1&ModuleNo=43515&doy=10m11

150W, 19V:

http://www.powersolve.co.uk/jkcm/cache/fl0000350.pdf

http://www.lambdapower.com

All are too big.

By the way, ATX power supplies have very small ability for -12V, so forget that route.

Good luck, Dave.

 

[TheRealMagicRat]

DaveScott,

That one 150 Watt, 19V model just might do it. I'm gonna buy one to see. It's right at the low end of the threshold, I think.

I think it will work with as low as 18.5V, 7.5Amp ... and no more than 22V, 11Amp. Using my bench. That's when it starts to smell a little bit like burning plastic (LOL).

I've tried ATX computer power supplies. I can get 24V out of them by connecting the standard +12 and -12 channels, but the current rating for the -12 is less than an AMP. I can't get by with that.

I'm going to see what that 150 Watt model you found can do ... that is exactly what I'm looking for (if it were just about 50 Watts more).

I'm also going to try to rebuild the whole project using 12V. That's going to take a month or so. I dunno if it will work. Damn.

 

[ScottyUK]

You might find it easier to migrate to 24V from 20V. Most of the commercial 24V supplies will trim down to 21V or so. Maybe a diode V_f drop after that? There are an incredible number of 24V modules out there - you've probably got enough leads to manuufacturers already, but Melcher / PowerOne, Astec Standard, Artesyn are all worth checking out.

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Sometimes I only open my mouth to swap feet...

 

[DaveScott]

Before you buy, there might be a better one:

160W, 20V, 8A adaptor.

http://www.made-in-china.com/showro...China-Switching-Power-Supply-SPS-Z160US-.html

 

[TheRealMagicRat]

Excellent, Dave.

Thank you.

 

[TheRealMagicRat]

UPDATE.

I noticed that my cordless drill, which uses an 18V battery has the exact dimensions I need.

A charged battery will yield 20V, 8.7 amps for about 30 minutes under load.

Amazing how powerful that battery pack is.

That's exactly what I need in a power supply.

 

[DaveScott]

Ah, a battery. That's another story.

If you only need 30 mins, then some of the power supplies have short term overload ratings.

You also might want to follow up on CJCPE's comment: running two adapters in parallel. You should check if they have current limit, and maybe a diode on the output of each would be a good idea. I really don't know if they could work in parallel - try it and see!

 

[itsmoked]

Expect smoke from two adapters!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com