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Re: Boost Converter Efficiency Improvements
On Mon, 10 Jun 2013 22:25:08 -0700, Bill Sloman wrote:

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Counting Sheep In Remote Outback :-)

--  
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled."
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Re: Boost Converter Efficiency Improvements
On Wednesday, 12 June 2013 04:01:05 UTC+10, Fred Abse  wrote:
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My aunt's husband did a bit of that - he once took a flock of sheep to Mara
linga, presumably just before the 1956 UK atom bomb test took place there.  
He died a few years ago (2009) at 90-odd. I doubt if the sheep did as well.
 He also worked on human metabolism and nutrition.

--  
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements

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Farnell was never a good alternativ to buy in Germany ferrites
and even more important: bobbins, clips, spacers, enameled wire and  
bundled wires etc.

I don't know if http://www.distrelec.com
or              http://www.buerklin.com
are exporting to outside EU you have to ask by email.
The online browsing and searching can't compare with Digikey
or Mousers. But if you look for EPCOS you may look there.

Those two above mentioned distributors had been since the early
beginning the reps and distributor for EPCOS.
Especially if you want a specific item like a small toroid without
a thick plastic coating just the naked core, which is listed, but
not stocked, you can go trough them to get an offer for a MOQ.

Although Philips had in Hamburg not far away from me their
ferrite laboratory, where the ferrox was once invented, they never
built up such good way offering their product line in Germany.  
Meanwhile they sold out many subdivisions to focus on their key biz.
Seems not too much know how left:
When I read last time an article about the Hue LED globe, I was
suprised: the engineers did not manage to have one transformer inside
working for wide range input 110VAC and 230 VAC otherwise
the transformer would not fit inside :-O

rgds Joerg


--  
Joerg Niggemeyer on Beagleboard running RiscOS
http://joerg-niggemeyer.de


Re: Boost Converter Efficiency Improvements
Joerg Niggemeyer wrote:
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Thanks. That would be good for EU clients.


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I won't do that here in the US anymore. Too many times I found that EU
vendors cannot properly handle international business. To the point
where on purchasing manager literally pleaded with me to change a part
in my design to a domestic inductor, or at least an Asian one. I found a
good source in Japan and all purchasing problems miraculously vanished.


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Yeah, the old Valvo. That is a sad story, it used to be a true
electronics powerhouse. They were very good to me as a student in
Germany when I needed parts and databooks. Still have most of those
databooks because many transistors and diodes didn't change over the
last 25 years. Actually I got into electronics via Philips, the EE-20
experimenter's kit:

http://ee.old.no/20/


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When I see how universities are nowadays teaching that is not at all a
surprise. Although it probably won't matter for screw-in bulbs because
the sockets are slightly different between the US and Europe. Not much
though, I have several German lamps with 120V bulbs and American CFL
here, one right next to the PC.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
On Tue, 04 Jun 2013 19:02:55 -0700, John Larkin

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<SNIP>

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I don't believe the 96% at all, I would be very happy if it got to 90%
in reality though.

Tapped inductors are not something I've looked at before... I thought  
they were a bit boutique. Something like a Bourns SRF1280 type seems  
to be easily available though and I won't need to 1uF between the two  
inductors any more.  

Interesting idea, thanks. I've got a couple of those inductors on  
order.


Dave.

Re: Boost Converter Efficiency Improvements
David Jordan wrote:
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217
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Coilcraft makes duals, too. They are very much mainstream these days and
I use them in switchers all the time.


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In the simulation one should set the coupling coefficient to around
0.98. That's where it realistically is for most of them. Unfortunately
SPICE does not easily take core losses into account. When simulating
loop behavior set it back to 1 for the initial runs because that saves a
lot of CPU runtime.

If you are ordering stuff anyway, why not add a few mains flybacks, CCFL
transformers and PoE flybacks? Those are cheap.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements

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If you build a regular buck or boost switcher with one winding, you get free AC
out of the other winding. For floating supplies, negative supplies, whatever.


--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
John Larkin wrote:
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217
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AC
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Psssst, don't reveal all the tricks of the trade. At least not without
getting a beer at Zeitgeist out of it  :-)

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements

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at 217
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AC
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Oh, there are so many tricks that no great harm is done by giving a few away.
Besides, so few people on Usenet are actually going to ever do anything.

Hey, look for Sofie Goose Island Belgian Style Farmhouse Ale, in a big black
wine bottle. We got some at Whole Foods (aka Whole Paycheck.)


--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
On Wednesday, June 5, 2013 5:59:15 PM UTC+2, John Larkin wrote:
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at 217
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free AC
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whatever.
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Somebody should write a book on all the nice tricks like this, to do all good
for mankind :-)

Cheers

Klaus

Re: Boost Converter Efficiency Improvements
On 6/4/2013 7:44 PM, David Jordan wrote:
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It appears from your LTSpice circuit that the big culprit is C1 with  
about a half watt of loss. Maybe concentrate on that one first.


Re: Boost Converter Efficiency Improvements
On 6/5/2013 9:49 AM, John S wrote:
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Or use JL's boost circuit.

Re: Boost Converter Efficiency Improvements

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Cap ESR loss could matter in a boost, with high peak current into a small cap.

I don't entirely trust that diode, either.


--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
On 6/5/2013 10:32 AM, John Larkin wrote:
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It does. It is the major contributor.

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Plug in a UPSC600. That might put you at ease.

Re: Boost Converter Efficiency Improvements
wrote:

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<SNIP>

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You're right, 350mA there gives around 400mW loss. Hopefully when I  
change that for a ceramic, a lot of that should go away. I haven't yet
found the ESR for the 1uF 250V part I'm going to use but it should be  
less than 100mR.


Dave.

Re: Boost Converter Efficiency Improvements
David Jordan wrote:
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On a ceramic cap the ESR is normally miniscule. Just stay away (in this
case) from ceramic caps with deliberately increased ESRs as they would
be necessary for those dreaded LDOs and stuff:

http://www.eetimes.com/electronics-news/4192016/TDK--MLCC-capacitors-offer-settable-ESR

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
wrote:

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Here're a few results from my recent experimentation:

I've been able to increase the frequency to 80kHz using the method  
discussed earlier. I have tested several different inductors on my  
original PCB that was giving me 79.4% efficiency at 4W output.

                                                        Efficiency
COILTRONICS     HC9-470-R               47uH    3.65A   77.0%
COILCRAFT       DO5022P-473MLD          47uH    2.6A    77.5%
EPCOS           B82477P4473M000         47uH    2.8A    77.5%
COILCRAFT       MSS1210-104KEB          100uH   3.4A    79.4%
WURTH           7447709101              100uH   2.8A    79.6%
COILCRAFT       DO5040H-473MLD          47uH    3.7A    80.3%
COILCRAFT       MSS1260T-104MLB         100uH   2.1A    81.7%
COILCRAFT       DO5040H-104MLD          100uH   2.8A    82.5%


I did another PCB layout using an MCP1407 FET driver, a lower gate  
charge FET, the DO5040H-104MLD inductors and 1uF ceramic capacitors  
replacing the electrolytics.

The FET driver gives a 23ns rise time and a 22ns fall time at the  
gate, a huge improvement.

The efficiency is now 85.5%, A 6% improvement.  


I also did another PCB using a tapped inductor as suggested by John  
Larkin, an SRF1280 47uH. This version got to 85.8% efficiency and has  
about half the number of parts and takes less board space.

The single inductor has around a 22C temp rise. The FET, now a DPAK,  
has around a 10C rise but some of that may be being conducted back  
from the inductor.

The only downside so far is slightly higher RF emissions.

If there're no major EMC problems, I think the winner for my  
application is obvious.

Thanks everyone!


Dave.

Re: Boost Converter Efficiency Improvements
David Jordan wrote:
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http://www.eetimes.com/electronics-news/4192016/TDK--MLCC-capacitors-offer-settable-ESR
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That indicates significant differences in core loss. It does not
surprise me much that Coilcraft and Wuerth score better.

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That's almost all in the layout.


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Great. Considering the extreme step-up ratio and the low output power I
think 85% is quite a respectable efficiency. The 22C rise on the
inductor is still a bit high for my taste but that might be as good as
it gets with catalog parts.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
On Saturday, June 15, 2013 9:47:31 PM UTC+2, Joerg wrote:
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http://www.eetimes.com/electronics-news/4192016/TDK--MLCC-capacitors-offer-settable-ESR
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Choose a bigger catalog part with higher peak current limit. It will have lower
RDC and higher saturation limit. That will reduce copper losses and core losses
since you will be working at a lower peak flux.

Regards

Klaus

Re: Boost Converter Efficiency Improvements
Klaus Kragelund wrote:
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[...]

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I think David already has the biggest one on there that will fit.

--  
Regards, Joerg

http://www.analogconsultants.com/

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