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 Post subject: Efficiency of 90% possible?
PostPosted: Tue Dec 05, 2006 10:39 pm 
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I keep hoping for a "premium" PSU that is 90% efficient at the 100-200 Watt range. The power range my PC actually runs at. Is it technically feasible?


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PostPosted: Wed Dec 06, 2006 3:48 am 
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vincentfox wrote:
I keep hoping for a "premium" PSU that is 90% efficient at the 100-200 Watt range. The power range my PC actually runs at. Is it technically feasible?


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

Quote:
In all SMPS topologies, the transistors are always fully on or fully off. Thus, an "ideal" SMPS will be 100% efficient. The only heat generated is because ideal components do not exist. Switching losses in the main switching transistors, non-zero resistance in the "on" state, and rectifier voltage drop will produce a fair amount of heat. However, by optimizing SMPS design, the amount of heat produced can be minimized. A good design can have an efficiency of more than 95%.


So it is technically feasible. And PicoPSU+ power brick has already demonstrated efficiency of 87%. However, the cost of making such an efficient PSU may not make economic sense for the big PSU manufacturers; it will be a low-volume product, and even at premium prices may not recoup development costs.


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PostPosted: Wed Dec 06, 2006 4:39 am 
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"Everything is (seems to be) impossible, untill it's done"


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PostPosted: Wed Dec 06, 2006 11:05 am 
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Perhaps some day there'll be ATX PSUs with 12V-only output. Then we'll see much higher efficiencies.

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PostPosted: Wed Dec 06, 2006 12:02 pm 
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"Possible... But very expensive!" (old russian anecdote)

Very high frequency switching, ultrafast MOSFETs, synchronous rectifier instead of diodes... Possible, but unprofitable for manufacturers, such PSU will cost too much. Maybe some years later...


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PostPosted: Wed Dec 06, 2006 8:48 pm 
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Well PicoPSU seems to be doing fine, so there are obviously niche markets that can do well.

However, the problem I have is wanting to build a DECENT multi-purpose PC with a Core2 Duo and a 7600GT. No matter how you minimize you still need a PSU capable of up to 200 Watts for that. Largest PicoPSU says 120 Watts. Perhaps if they built a heavier version?

No one is optimizing for a "normal" power range. Every review I read at SPCR seems to show <80% in the 90-150 Watt range. The claimed 80+ only comes at 300 Watts and up.


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PostPosted: Wed Dec 06, 2006 10:49 pm 
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Possible? Yes, it's technically possible. However, so far as I know, there are no actual products that approach this.

Side note: It's probably easier to find a product like this in regions that use 230VAC power, since most power supplies are slightly more efficient at this voltage compared to North America's 120VAC power grid.


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PostPosted: Thu Dec 07, 2006 3:34 am 
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Quote:
the problem I have is wanting to build a DECENT multi-purpose PC with a Core2 Duo and a 7600GT. No matter how you minimize you still need a PSU capable of up to 200 Watts for that.


Not necessarily. C2D TDP is 65W, max consumption of 7600GT is 36W as measured by Xbitlabs, you still have enough for a laptop hard drive, RAM etc.

Quote:
Largest PicoPSU says 120 Watts. Perhaps if they built a heavier version?

No one is optimizing for a "normal" power range


The PicoPSU is not the only DC-DC converter on the market you know. For example the PW200M targets exactly the power range you are talking about.


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PostPosted: Thu Dec 07, 2006 7:45 am 
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vincentfox wrote:
No one is optimizing for a "normal" power range. Every review I read at SPCR seems to show <80% in the 90-150 Watt range. The claimed 80+ only comes at 300 Watts and up.


http://www.80plus.org/


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PostPosted: Thu Dec 07, 2006 9:15 am 
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Regarding the PW-200M, what's the efficiency of this device from the wall to the motherboard? I find references to over 90% for the DC-DC board, but the brick is not being factored in there.....


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 Post subject:
PostPosted: Thu Dec 07, 2006 10:27 am 
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vincentfox wrote:
Regarding the PW-200M, what's the efficiency of this device from the wall to the motherboard? I find references to over 90% for the DC-DC board, but the brick is not being factored in there.....


Well, if the AC/DC brick is 95% efficient (which is high but not impossible) and the PW200M is 95% also, then it's slightly less than 90% or thereabouts.


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 Post subject:
PostPosted: Thu Dec 07, 2006 10:39 am 
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Bricks I have looked at so far list max efficiency 84%.


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PostPosted: Thu Dec 07, 2006 11:22 am 
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OK then the total efficiency will be a lot lower, in which case it's very questionable whether you will see any benefit from going for AC/DC brick + DC/DC board over a normal PSU like Seasonic SS-300SFD 80 Plus which is 85% efficient @ 100-200W. The only positive of the brick + DC/DC in that case is that it moves some heat-generating components outside of the case, making it easier to cool.

Frankly, the difference in watts between an 85% and 90% efficient PSU at the load levels you are talking about is always going to be in single figures; if your aim is to save energy, get some energy-saving lightbulbs.


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PostPosted: Thu Dec 07, 2006 3:13 pm 
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You can always make the lightbulb argument regarding a 70% versus 80% PSU. Or that the first place to look for household energy-saving is at your HVAC, fridge, or washer/dryer units.

I didn't start this thread with a question about saving money on my electric bill. I'm interested in what is the edge of what is possible here. With all the whacky "enthusiast" luxury items out there like windowed cases and PicoPSU this seems like a niche no one has really explored yet.


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 Post subject:
PostPosted: Thu Dec 07, 2006 5:54 pm 
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90% efficiency is possible and has been achieved for single DC line output adapters. Efficiency Challenge 2004was a competition for energy efficient ac-dc power supplies. It was sponsored jointly by California Energy Commission's PIER program and the EPA's ENERGY STAR program. EPRI, Ecos Consulting (80 Plus), and EPRI Solutions Inc., as contractors to the PIER program, assisted with the development and facilitation of the design competition.

In the Desktop replacement laptop computer power supply category, Acbel's API 3 D25-380 won best of class.
Quote:
Average Efficiency 90%
Output Power - 150 W
Output Voltage - 19 V
Output Current - 7.9 A
Judges Comment(s): This product is particularly remarkable because it has an average of 90% efficiency in active mode and still achieves outstanding power factor correction (average of 0.99 across four loading points).

http://www.efficientpowersupplies.org/p ... _sheet.pdf

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 Post subject:
PostPosted: Thu Dec 07, 2006 11:30 pm 
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Wow, now that is the kind of information I was looking for. Thanks!


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 Post subject:
PostPosted: Sun Dec 10, 2006 1:40 am 
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MikeC wrote:
Efficiency Challenge 2004was a competition for energy efficient ac-dc power supplies. It was sponsored jointly by California Energy Commission's PIER program and the EPA's ENERGY STAR program.


Cool! Thanks!


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 Post subject:
PostPosted: Sun Dec 10, 2006 10:10 am 
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Great link, MikeC. According to the Judging Process document on the 2004 Design Competition website, the Acbel API 3 D25-380 is 90%+ efficient at 37.5W, 75W, 112.5W, and 150W - that beats out the Seasonic SS-300SFD 80 Plus as the new low-power efficiency champ, assuming a DC-DC PSU of better than 90% efficiency (like the PicoPSU).

I also found this power brick for sale at Shentech here - ~$59 shipped.

Note that this brick could be a fantastic match for the SPCR-reviewed AOpen i945GTt-VFA, which has a 19V DC-DC PSU built-in.


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 Post subject:
PostPosted: Sun Dec 10, 2006 10:38 am 
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Linus wrote:
Note that this brick could be a fantastic match for the SPCR-reviewed AOpen i945GTt-VFA, which has a 19V DC-DC PSU built-in.

The Delta power brick that comes with the AOpen is already pretty good. It is is a Delta Electronics ADP-90SB BB. It is on Energy Star's list of Qualified External Power Supplies (PDF), which oddly cites 88% avg efficiency at 115VAC/60Hz and 85% at 230VAC/50Hz.

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 Post subject:
PostPosted: Sun Dec 10, 2006 12:46 pm 
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Ok, let's try to find out more 60W+ notebook style PSUs. Either 12V (PicoPSU, PW200) or 19V (AOpen i945GTt-VFA).

Acbel API 3 D25-380 - 19V - 150W - "average of 90%" at 25,50,75,100% @110V source 1, 2, shop
Delta ADP-90SB BB - 19V - 90W - 88%@115V and 85%@230V, energy star, comes with the AOpen i945GTt-VFA
Delta ADP-120SB X - 19V - 120W - 89%@115V and 90%@230V, energy star
Li Shin LSE9901B1260 - 12V - 60W - 85%@115V, 87%@230V, energy star
There are many more 19V 88%+ on the energy star pdf.

The best I could find in my prior research:
powerbox PUP120 Series - 12V - 96W - "86% min on all models", source
powerbox TR100 Series - 12V - 100W - "88% typical (12V version).", source
Craftec PSA80W - 12V - 80W - "87% under EPA Energy-Star measurement.", source
EQS ZVC90 - 12V - 80W - "Efficiency to 92%", source
Some more with "typical" and "up to" rating:
http://www.craftec.info/productPDF/pw132.pdf
http://www.craftec.info/productPDF/PW122.pdf
http://www.craftec.info/productPDF/PW116.pdf

Edit: I calculated the efficiency of the PSU supplied with the PicoPSU since the efficiency of the PicoPSU and PicoPSU+brick are known.
Edac EA112003A - 12V - 120W - 83% (delivering 23.5W DC @115V) and 88.5%(delivering 93W DC @115V)


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