If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #123
Joined: Fri Feb 10 2006, 12:58PM
Location:
Posts: 162
GeordieBoy wrote ...
I've read through the thread and I still don't understand one thing, why do I need to use 50% duty cycle on the gates?
There is some latitude in the gate-drive timing to the switches in the SLR inverter because the actual "turn-off" instant of the device is dictated by the resonant frequency of the load - not the gate-drive signal. As long as the gate drive is on for at least half the resonant period, and not on longer than one whole resonant period it works. That makes overall duty ratio for each switch between 0.25 and 0.50 for correct operation.
If you think about it the IGBT's in an SLR inverter actually operate like thyristors: Once they're turned on, they stay on until the current changes direction. And indeed inverter grade thyristors are sometimes used in SLR systems.
The free-wheeling current flows through the diode associated to to the same transistor that conducted the preceding halfwave right?
Load current commutation sequence:
+ve load current forced down from V+ through channel of Q1 -ve load current freewheels up to V+ through D1 -ve load current forced down to V- through channel of Q2 +ve load current freewheels up from V- through D2
Registered Member #205
Joined: Sat Feb 18 2006, 11:59AM
Location: Skørping, Denmark
Posts: 741
All,
Progress is slow, and with Finn on the starting list on a lot of training time is expected in the future, which means less time for nerdy electronics. Anyway, today we sort of finished winding the Transformer.
Here the first layer in the first section is complete.
Here is the interleaving, which we use between layers to keep the windings neat.
Here you get the picture. There are 4 turns in each layer, and it is best to have a fresh, cylindrical winding base for each layer.
Here you can see how the wire passes from one pie to the next:
And here is the finished article:
We measued the resonant frequency with a 500nF cap across the primary to be 131kHz, wheach means that we need a small series inductor to get the resonant frequency down to the design frequency of 100kHz.
That`s all for today, folks. A merry easter to you all.
Registered Member #205
Joined: Sat Feb 18 2006, 11:59AM
Location: Skørping, Denmark
Posts: 741
bob golding wrote ...
hi ultra, this should get you up to speed on ccps topology's
this was a long time before drsstc's solved some problems ,and created some others.:-))
Thanks, Bob
Yes, needless to say, Marco`s groundbreaking supply paved the way, and was our ultimate inspiration. I recall when Marco made it, how all this electronic stuff was way over my head, and I guess it still is.....
Registered Member #1084
Joined: Mon Oct 29 2007, 08:58PM
Location:
Posts: 28
hi finn, yes no one else was working on electroric power supplies back then in the dark days of the errrrmm late 1990's i feel a i have got as far as i can with SGTC coils apart from bigger. thats why i am getting into drsstc's as the next logical step now we can get the silicon at sensable prices.think ebay has played a big part in this , as buying al this stuff new is still very expensive. big filter caps are not cheap new. those 5800uF 400 volt ones are 330 euros each at RS!!! hope to see your new ccps at cambridge this year. last weekend of october, will confirm it later.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I made a "quick n' dirty" version today. Two fets in halfbridge are driven by GDT and ~40% deadtime. Here is the primary current waveform:
Ok, can anyone explain why the upper "butt" has first pulse smaller than the second, and the bottom "butt" has the first pulse bigger than the second one? The current is small, few A at most, and the Fets are heating quite a bit.
(ignore the negative ringing as it seems to be just some noise picked up by the scope)
Registered Member #618
Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628
I think it has to do with something similar to Class E waveforms, While testing out my idea of Class E\F I noticed rather similar wave forms mostly on the 2ndary side, where the wave form would start going (+) the secondary waveform would get about 30% (+) right as the direct drive fet transitionand from high to low the wave form would do the small butt, dip about 2-5% then shoot back up then go (-) and repeat on the (-) cycle Doing teh Big butt to little butt as teh inverted fet would transition from High to low.
Registered Member #191
Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720
you are driving it at 50% dutycycle. It starts with the 2nd hump of the butt(when you are actually feeding power to it), and then transistors are off, and you see the begining of a ringdown. and they cycle starts all over again in the opposite direction.
Registered Member #205
Joined: Sat Feb 18 2006, 11:59AM
Location: Skørping, Denmark
Posts: 741
Plasmaddict wrote ...
Ok, can anyone explain why the upper "butt" has first pulse smaller than the second, and the bottom "butt" has the first pulse bigger than the second one? The current is small, few A at most, and the Fets are heating quite a bit.
Plasmaddict
I see what you mean, and although I have no good explanation for it, we have seen the same picture up here several times.
It appears that you are pushing a larger current trough the transformer in one direction than in the other.
I would start by checking the dutycycle for symmetry
It is correct that we see ringdowns. It`s jst that one starts out bigger than the other.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
CCPS (Capacitor Charging Power Supply)
