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Re: Boost Converter Efficiency Improvements
On 6/4/2013 3:15 PM, David Jordan wrote:
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Wall wart flyback transformers are available.
Run such transformer in backward direction.

Vladimir Vassilevsky
DSP and Mixed Signal Designs
www.abvolt.com


Re: Boost Converter Efficiency Improvements
On Tue, 04 Jun 2013 21:15:43 +0100, David Jordan

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Got a schematic?

That's a high boost ratio for what is (I think) a 2:1 inductor stepup
ratio. A lot of energy is going to go into charging and discharging
capacitances.

Have you considered a C-W type multiplier? Diode drops won't cost much
efficiency at 200 volts out, and you could get the basic boost ratio
down by some factor.

I like to make boost converters using a 1:1 dual-winding inductor to
double the p-p swing.



+12-------/////--+--/////--------|>|------ HV
                 |
                nfet      (diode or C-W thing)
                 |
                gnd




--  

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Re: Boost Converter Efficiency Improvements
On Tuesday, June 4, 2013 11:00:44 PM UTC+2, John Larkin wrote:
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With the coupled boost converter solution, you need to be carefull with the
 FET ratings.

You would assume that you can rate the VDS lower due to the autotransformer
 action, but leakage inductance ringing forces you to add a snubber. Other  
solutions is to add a diode from the tapped point to the output to quinch t
he ringing and regenerate the leakage energy, but then you cannot use lower
 voltage rated FETs.

Regards

Klaus


Re: Boost Converter Efficiency Improvements
wrote:

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ratings.
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action, but leakage inductance ringing forces you to add a snubber. Other
solutions is to add a diode from the tapped point to the output to quinch the
ringing and regenerate the leakage energy, but then you cannot use lower voltage
rated FETs.
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Yeah, most flyback architectures need a snubber, and that wrecks efficiency.

Without a snubber, the energy left over in tne magnetizing inductance gets lost
just the same, but it makes a lot of ringing noise and overvoltage, which might
be OK.

I guess it might be possible to time the period of the fet drive to synchronize
with the magnetizing ringing, to use instead of lose some of the energy.

The OP is running low power, so he can just buy a higher-voltage fet without a
big penalty, and let it ring. Or run in continuous mode.



--  

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

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Re: Boost Converter Efficiency Improvements
On 04/06/13 22.15, David Jordan wrote:
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Your on-time is "long" and your off-time where the inductor delivers  
200V is short.

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You mayvbe need to measure if the diodes "shorts" for some time at the  
end of off-time. If so, then considerably energy might be lost during  
output capacitor discharge.

Use Silicon-carbide diode (?) if you increase your frequency considerably:
http://www.digikey.com/product-search/en/discrete-semiconductor-products/diodes-rectifiers-single/1376383?k=sic%20diode

CSD01060A, No Recovery Time > 500mA (Io). Can they be bought with  
smaller current rating?:
http://www.digikey.com/product-detail/en/CSD01060A/CSD01060A-ND/1244253

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You could try to decouple with 100nF and 10nF?

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Mayby you should consider another topology?:

* Cuk-converter

* transformer/flyback

?uk converter:
http://en.wikipedia.org/wiki/%C4%86uk_converter

home.netvigator.com: Cuk converter:
http://home.netvigator.com/~blessyou/cuk.html
Quote: "...The Cuk converter is a new SMPS topology at this moment. It  
include higher efficiency, low input and output current ripple, minimal  
RFI, small size and weight..."

Use an isolated Cuk-converter:
http://www.boostbuck.com/IsolationoftheCukConverter.html

-

September 1, 1994 Cuk converter yields 90% efficiency
Peter Demchenko,
VN, Vilnius, Lithuania
http://www.ednmag.com/archives/1994/090194/18di3.htm
http://www.ednmag.com/archives/1994/090194/Images/18DI3FG1.GIF
Ccuk=6,8nF ?? PS: Low power.

/Glenn

Re: Boost Converter Efficiency Improvements
Glenn wrote:
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Yup. Roughly 1.25usec and the 170nsec are grossly eating into that,
dissipating stored energy.

I'd probably get a CCFL transformer and use that instead.

[...]

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
wrote:

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It's not that bad, the duty cycle is around 40% for 200V. Take a look  
at the attached schematic. I didn't model the gate driver but the  
pulse source rise/fall times are approximately correct.

Version 4
SHEET 1 880 696
WIRE -32 128 -224 128
WIRE 288 128 32 128
WIRE -560 192 -720 192
WIRE -432 192 -560 192
WIRE -240 192 -352 192
WIRE -224 192 -224 128
WIRE -224 192 -240 192
WIRE -144 192 -224 192
WIRE 16 192 -80 192
WIRE 144 192 16 192
WIRE 288 192 288 128
WIRE 288 192 224 192
WIRE 336 192 288 192
WIRE 480 192 400 192
WIRE 640 192 480 192
WIRE -240 272 -240 192
WIRE 16 288 16 192
WIRE 480 288 480 192
WIRE -720 304 -720 192
WIRE -400 352 -448 352
WIRE -288 352 -320 352
WIRE 640 352 640 192
WIRE -560 368 -560 192
WIRE -448 416 -448 352
WIRE -720 592 -720 384
WIRE -560 592 -560 432
WIRE -560 592 -720 592
WIRE -448 592 -448 496
WIRE -448 592 -560 592
WIRE -240 592 -240 368
WIRE -240 592 -448 592
WIRE 16 592 16 352
WIRE 16 592 -240 592
WIRE 480 592 480 352
WIRE 480 592 16 592
WIRE 640 592 640 432
WIRE 640 592 480 592
WIRE -720 656 -720 592
FLAG -720 656 0
SYMBOL ind -448 208 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 100µ
SYMATTR SpiceLine Ipk=3.4 Rser=0.13
SYMBOL diode -144 208 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value ES1D
SYMBOL cap 0 288 R0
SYMATTR InstName C1
SYMATTR Value 4µ7
SYMATTR SpiceLine Rser=3.2
SYMBOL res -304 336 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 1m
SYMBOL voltage -720 288 R0
WINDOW 123 0 0 Left 2
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL voltage -448 400 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 12 0 100n 200n 8u5 25u)
SYMBOL cap -576 368 R0
SYMATTR InstName C2
SYMATTR Value 1000µ
SYMATTR SpiceLine Rser=0.02
SYMBOL nmos -288 272 R0
SYMATTR InstName M1
SYMATTR Value IPP110N20N3
SYMBOL ind 128 208 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L2
SYMATTR Value 100µ
SYMATTR SpiceLine Ipk=3.4 Rser=0.13
SYMBOL diode 336 208 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D2
SYMATTR Value ES1D
SYMBOL cap 464 288 R0
SYMATTR InstName C3
SYMATTR Value 4µ7
SYMATTR SpiceLine Rser=3.2
SYMBOL res 624 336 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL cap 32 112 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 1µ
TEXT -704 680 Left 2 !.tran 0 100m 0



Dave.

Re: Boost Converter Efficiency Improvements
On Wed, 05 Jun 2013 01:44:22 +0100, David Jordan

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This is a tapped-inductor boost. It shows an improbable 96.4% efficiency at 217
volts out. I added a few parts for observability.

There are lots of nice surface-mount dual-winding inductors around.


Version 4
SHEET 1 880 696
WIRE -672 192 -720 192
WIRE -560 192 -592 192
WIRE -432 192 -560 192
WIRE -240 192 -352 192
WIRE -176 192 -240 192
WIRE -64 192 -176 192
WIRE 96 192 16 192
WIRE 144 192 96 192
WIRE 288 192 208 192
WIRE 368 192 288 192
WIRE 448 192 368 192
WIRE 544 192 448 192
WIRE 656 192 624 192
WIRE 688 192 656 192
WIRE -240 272 -240 192
WIRE 288 288 288 192
WIRE -720 304 -720 192
WIRE -400 352 -448 352
WIRE -304 352 -320 352
WIRE -288 352 -304 352
WIRE 448 352 448 192
WIRE 688 352 688 192
WIRE -560 368 -560 192
WIRE -448 416 -448 352
WIRE -720 592 -720 384
WIRE -560 592 -560 432
WIRE -560 592 -720 592
WIRE -448 592 -448 496
WIRE -448 592 -560 592
WIRE -240 592 -240 368
WIRE -240 592 -448 592
WIRE 288 592 288 352
WIRE 288 592 -240 592
WIRE 448 592 448 432
WIRE 448 592 288 592
WIRE 688 592 688 416
WIRE 688 592 448 592
WIRE -720 656 -720 592
FLAG -720 656 0
FLAG -304 352 G
FLAG -176 192 D
FLAG 368 192 OUT
FLAG 96 192 BOOST
FLAG 656 192 FILT
SYMBOL ind2 -448 208 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 100µ
SYMATTR SpiceLine Ipk=3.4 Rser=0.13
SYMATTR Type ind
SYMBOL res -304 336 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 20
SYMBOL voltage -720 288 R0
WINDOW 123 0 0 Left 2
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL voltage -448 400 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 12 0 100n 200n 12u 25u)
SYMBOL cap -576 368 R0
SYMATTR InstName C2
SYMATTR Value 1000µ
SYMATTR SpiceLine Rser=0.02
SYMBOL nmos -288 272 R0
SYMATTR InstName M1
SYMATTR Value IPP110N20N3
SYMBOL ind2 -80 208 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L2
SYMATTR Value 100µ
SYMATTR SpiceLine Ipk=3.4 Rser=0.13
SYMATTR Type ind
SYMBOL diode 144 208 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D2
SYMATTR Value ES1D
SYMBOL cap 272 288 R0
SYMATTR InstName C3
SYMATTR Value 1µ
SYMATTR SpiceLine Rser=3.2
SYMBOL res 432 336 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL ind -688 208 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L3
SYMATTR Value 50µ
SYMBOL res 640 176 R90
WINDOW 0 71 60 VBottom 2
WINDOW 3 83 54 VTop 2
SYMATTR InstName R3
SYMATTR Value 10K
SYMBOL cap 672 352 R0
SYMATTR InstName C1
SYMATTR Value 100n
TEXT 72 352 Left 2 !.tran 0 30m 0
TEXT -216 112 Left 2 !K L1 L2 1
TEXT 16 424 Left 2 ;JL's Boost  June 4, 2013



--  

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

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Re: Boost Converter Efficiency Improvements
On Jun 5, 12:02 pm, John Larkin
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at 217

<snipped LTspice circuit>

96% would be high, but the classic circuit for the job - Peter
Baxandall's class-D oscillator - usually gets pretty close

Peter Baxandall described his parallel- and series-resonant class-D
oscillators in 1959 in a paper in the Proceedings of the (British)
Institute of Electrical Engineers (P.J.Baxandall "Transistor sine-wave
LC oscillators, some general considerations and new developments"
Proc. I.E.E. vol. 106, part B, supplement 16 pages 748-58, May 1959).
It's hard to get hold of, so my web-page discussing the circuit

http://home.planet.nl/~sloma000/Baxandall%20parallel-resonant%20Class-D%20o
scillator1.htm

provides a link to a pdf copy of the paper.

http://home.planet.nl/~sloma000/0344_001_Baxandal.pdf

He is reputed to have developed the circuit for driving high turns-
ratio step-up transformers ? which tend to have low self-resonant
frequencies ? being used to generate high output voltages from battery-
level inputs.

The circuit is probably best known from Jim Williams? series of
application notes for Linear Technology, on high frequency inverters
for driving cold cathode back-lights used in laptop computers
(application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams
describes the inverter as a current-driven Royer inverter, referring
back to the non-resonant inverter described by Bright, Pittman and
George H. Royer  in  1954 in a paper ?Transistors as on-off switches
in saturable core circuits? in Electrical Manufacturing. AN65 does
include a reference to Peter Baxandall, but to his 1960 paper
?Transistor Sine-Wave LC Oscillators? in the British Journal of the
IEEE paper number 2978E which is cited in a discussion of root-mean-
square power measurements.

As Jim Williams points out, this circuit can offer good efficiency ?
90% - when driving difficult loads. Even when lightly loaded, it
produces a slightly distorted sine wave, with an appreciable odd
harmonic content, about one percent of the third harmonic, and
decreasing proportions of the higher odd harmonics.

--
Bill Sloman, Sydney


Re: Boost Converter Efficiency Improvements
In message < snipped-for-privacy@d8g2000pbe.googlegrou  
ps.com>


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Interesting but for a DCDC step up I can't see that this inverter is  
the classic approach. All automotive HID ballasts which are using an  
internal conversion:
5V-32V -> 30VDC-500VDC -> inverter square wave to bulb
are using flyback transformers.

If in case you need just 5W at fixed 200VDC you can do that with a  
very small transformer core already like RM6.
In case you want to have it as a compact type you may use a planar
transformer and hang it into cut outs of the PCB itself, etc.

Because you may not like or are used to develop your own transformers  
for such applications and want also an SMD type, it makes sense to  
start to google for such step up transformer and base the design on  
it.

If the project is high volume and you have no luck finding existing  
type, I am sure you can get full design support for instance from  
EPCOS and they will supply you transformer samples based on the specs.  

I have also some small SMD bobbins in mind like from SUMIDA EFD15

But like the other Joerg already mentioned you may just work on the
details of the existing design for some improvements here and  
there......

Joerg




--  

Nucon Gesellschaft bürgerlichen Rechts Geschäftsführer: Joerg  
Niggemeyer & Gert G.Niggemeyer  Email: snipped-for-privacy@nucon.de WEB:  
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Re: Boost Converter Efficiency Improvements
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It's the approach that copes most elegantly with the relatively high
interwinding capacitances and low self-resonant frequencies of high
turns-ratio transformers.

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The Baxandall circuit uses two cores - one for an inductor and the
other for the transformer. This makes it expensive in very high-volume
applications, where it can be worth bank-winding a single inductor to
get low inter-winding capacitance.

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So nominate one.

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EPCOS makes cores and formers, and their application notes are the
best in the business, but I've never heard that they wind coils for
anybody - coil winding is pretty much a cottage industry.

For development work I've mostly wound my own - when I've been able to
get hold of a minimal coil-winding machine with a built-in turns
counter.

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Voltage step-up applications do tend to be idiosyncratic. Jim
Williams' series of application notes are aimed at a single
application -  high frequency inverters for driving cold cathode back-
lights used in laptop computers. The curious thing is that he latched
onto the Baxandall architecture - probably from a U.K. informant - and
ran with it.

The Baxandall approach is one of the existing designs, and definitely
worht looking at.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
In message < snipped-for-privacy@ow4g2000pbc.googlegro  
ups.com>

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<snip>

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When using a PCB planar transformer you don't suffer on those
interwinding capacities.

On our own ballasts we do 2 turns on the primary and 10 on the  
secondary. On a ELP22 core set gapped with 100um.
Runs with output max 75W avg 200DC of input 10DC can generate up
to 600V with a transformer ratio of just 5 :-O

Because it's not a sinus driven transformer you don't need
that high transformer ratios, the switch off speed gives you
the high volts.

Because you have only low volt you must reach some amps to
get the energy stored into the core - you won't do that with
the transistors of what have been available the last century.


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Actually they don't wind for anybody, that's what I said and
they are only to considered if you need their quality otherwise
it's too expensive.

But they had or still have an EHP16-SMD Xenon transformer
3/15/8
L 1-2 1.4uH
Rdc 11/105/205 mOhms
H 10mm 23mm gullwing distance width 16mm
http://www.nucon,de/infos/Xenon_Standard_3279_A2.pdf

(I have of that type of transformer EHP19 samples available
4:24.15  primary inductance 5uH  9mR/210mR/165mR)

In case you need just some transformers and you know
what type you can try to go to some Chinese companies
and pay some bucks to get ready wound samples for little
money only.

The ferrite powder EPCOS or Ferrox is using is from CHina
anyhow. Custom design of transformers is not expensive there.

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I like todo the copper windings in the PCBs, this is very precise and  
no one makes a mistake or crosses a wire on another and is covered by  
this yellow tape......

If I am winding my owns I have an more than 50 yers old drilling
machine from the US with a mechanic gear to make very slow
turns and having a very hi force available for bending thick
wires arroung small bobbins :-)    yes the clock counter is a must  
have.......


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That's dam right
but the software control of the PWM generation
is in this critical designs very important too and gives you nowadays  
the option to get rid of most analogue PWM ICs,  their shunts and even  
worse their "nice" compensation networks, because we have
now inexpensive micros in our hands which get by software the
safe operating areas and the reg speed simply coded.
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Those type of converters are driving an AC high voltage load directly.
It makes no sense to use for Cold cathode: DCDC plus 50Khz inverter.
The inverters can be designed and operated by none or primitive PWM  
generators.
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Yes it is very good to have a look on old circuit design, because
it was not yet the time of AN cookbook design finding the right
IC or component over the internet.
Because this base principle was already working well with old semis
for the CCL application  the type of transformer and the principle is  
still working very well and even better with modern switches.



However if you need a DCDC converter from input 12V and 0V-200V
also controlable on a shortened output, minimum, no load, etc.
or for fast charging up flash cap, I prefer to you use the flyback.
If it must be a transformer for the 200VDC here it is to be fined out
and it depends on price and if it's available ;-)

rgds

Joerg

--  

Nucon Gesellschaft bürgerlichen Rechts Geschäftsführer: Joerg  
Niggemeyer & Gert G.Niggemeyer  Email: snipped-for-privacy@nucon.de WEB:  
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Re: Boost Converter Efficiency Improvements
wrote:
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Of course you do. You've got more control over them, but some inter-
winding capacitance is inevitable.

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Back in the last century I built a couple of electronic ignition
circuits to drive the induction coils in my cars. I used SCR's to
deliver the multi-ampere currents involved, but transistors were
developed for that market.

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tandard_3279_A2.pdf
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Sure you can, if you don't mind the communications problems. Getting
something made by somebody you can talk to face-to-face has its
advantages. Development time saved can be worth quite a lot of money.

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In custom design, you get what you pay for. Ferrite core powder is
quite a way from completed ferrite cores - EPCOS/TDK does add value
when it turns them into cores.

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Copper density isn't great.

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-
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It looks as if Baxandall invented his inverter for generating roughly
1kV DC voltages for photomuliplier tubes from 24V DC rails. I can't
guarantee this - it based on gossip with a very good engineer who did
his electronic apprenticeship at the Royal Radar Establishment at
Malvern, supervised by Peter Baxandall amongst others. Jim Williams
latched onto it for CCLs much later.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:

[...]


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Oh c'mon, Bill. There is a plethora of COTS flyback transformers
available. Such as this example for a buck fifty:

http://productfinder.pulseeng.com/products/datasheets/P563.pdf


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Fast forward to the 21st century. There's lots of companies who will
gladly wind prototypes and production volumens for you. Last time for me
was a few months ago when we needed a really odd form factor.

[...]

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
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I wasn't arguing that they didn't exist, merely that if you claim that
such a device is available off the shelf, you are obliged to point to
at least one example.

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Sure. And I can recommend ACE-Wikkeltechniek
( snipped-for-privacy@acewikkeltechniek.nl) to anybody in the Netherlands.
Sadly, EPCOS won't wind prototypes for you - as I said, coil winding
is still pretty much a cottage industry. Some of the bigger cottages
run to machines that can more-or-less mass produce toroidal
transformers, but the capital involved still falls a number of orders
of magnitudes short of the EPCOSs of this world.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:
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That would be like requiring someone to point out bread on the shelves
at Safeway, after claiming that bread is available in America. Or sand
on the beaches.


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Sure they take custom orders. Epcos is now part of TDK.

http://www.tdk.co.jp/ferrite_cus_e/bec01000.htm

Quote "Even single items can be ordered! ... Customers can order low
quantities for product development, special usages, and development
studies including orders for single products. Please contact us about
low-quantity orders".

Now how much more clearly could they say it?


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Then just buy'em ready to eat:

http://www.epcos.com/inf/85/ds/b82802a.pdf

But as outlined above, you can also get custom orders processed there. I
personally prefer smaller companies because they can do more cutting
edge stuff. End of last year I had one flyback transformer where most
everyone said "It can't be done" and we did it anyhow.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
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:
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s

Rubbish. Tapped inductors are relatively rare. Pulse Engineering isn't
a broad-line distributor - if you'd found something at Farnell/Newark
who are the electronic equivalents of Safeway, you might have a case.

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s.
o
me

There's a big gap between supplying small quantities of cores and
formers for development work, and actually winding a coil onto one of
those formers. If you wave a big enough order in front of them they
may even make you special purpose ferrites, but they'd have to see the
prospect of very large sales before they'd devote much time or
resesource to your particular problem.

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... - as I said, coil winding
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If that's exactly what you want, and you can order a big enough batch
to get their attention. It's less than obvious that this would do what
the OP wanted, and highly unlikely that you could get anything that
wasn't on the data sheet if you weren't buying for a 10,000 unit a
year market.

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That happens. They mostly mean "it can't be done the way we usually do
it". Finding another way is the trick, but as soon as you have done
it, the same people will tell you that it's obvious.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:
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Rubbish? You really need to get out more. Further down I have given
another example from Epcos. Now if that's not a company you would
consider mainstream then I can't help you.

As for tapped inductors, you can easily buy those off the shelf from
Delevan, Bourns, Cooper, Sumida, TT, Wuerth, and on and on. A custom
order would have been needed in 1970 but this is the 21st century.

So you want something from Newark? Voila:

http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-efd20/dp/43W5642?in_merch=Popular%20Pulse%20Transformers&MER=PPSO_N_P_Pulse_None
http://www.newark.com/wurth-elektronik/750311308/trans-flyback-lt3575-lt3574-100uh/dp/47T5826?in_merch=Popular%20Pulse%20Transformers&MER=PPSO_N_P_Pulse_None

Why were you not able to see those yourself?


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Yesterday your story was, quote "Sadly, EPCOS won't wind prototypes for
you". And that is obviously wrong.

As for NRE, that is the same with all companies or they'd go under.
Either you pay hefty NRE or you'll have to dangle a big order in front
of them. What is so unusual about that?


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This was merely one example. You can get lots of these off the shelf,
and David could just pick one that is for European voltage supplies,
then use it in reverse. Has to be big enough to ferry the 4 watts across
because at his low frequency of 40kHz the energy has to be "tossed over"
in chunks. Most such flyback transformers are optimized for 100-150kHz,
for obvious reasons.

If you read up on how flybacks work you'll see that such supplies are
very flexible when it comes to turns ratio. There are a few trade-offs
but I have designed converters that can be steered more than 3:1 in
their output voltage.


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Many of them weren't even willing to try a different more modern ferrite
even after I looked up all the data for them. In that business, one
quickly finds out who are the true leaders in the industry. The ones
with the loudest advertising are often not the leaders.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements

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Sloman is generally both obnoxious and wrong, a stupid combination. Digikey
offers tons of dual-winding inductors from several vendors. The duals make nice
transformers, too. Most are surface mount. Coiltronics DRQ series, as one
example.

He also seems to think that Farnell is the only distributor in the world.


--  

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

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Re: Boost Converter Efficiency Improvements
On Jun 7, 1:41 am, John Larkin
:
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ote:
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a
r
mers
o
on
at
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s
d

John Larkin finds it obnoxous when I prove him wrong, which happens
too often to suit him. He reduces the damage to his sensitive psyche
by practicing denial, which is indeed stupid, but he can't do better.

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uals make nice
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They do offer a few. The chances are they won't offer one that will do
the job you want.

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John Larkin infers this from the fact that I usually use Farnell as my
example of a broad-line distributor - I'm used to the web-site, and
know my way around it. This doesn't mean that I think that it's the
only broad-line distributor - my most recent reference to Digikey as a
distributor was on the 17th April this year, in the thread "Grinding
Ferrite" but John Larkin's memory is as weak as his logic.

--
Bill Sloman, Sydney

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