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 #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ok so now im on the power side circuit.
you've all recommended the half bridge over the P-P. so what about that capacitor ? I have know idea how to include that. is it a film, electrolytic or ceramic ? and how do I calculate the value ?
Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
If you are referring to the capacitive voltage divider that forms one of the legs of the bridge, you want big PP or electrolytic or both. The value should be nice and big to reduce the voltage fluctuation at the centre-point of the divider. You can work out a rough approximation of the capacitor values needed using the full-wave ripple voltage calculation. I/(f*Vripple) = C I choose a current of 10A to account for magnetising current plus full current under load, a frequency of 50 kHz (you might want to change that to suit) and a ripple voltage of 0.5 V (just a nice low number) that comes out to 400 uF, but that includes both the high side and low side capacitors, as they are both connected to low impedance sources. So about 200 uF per capacitor. I would break this up further into a couple of paralleled electrolytic of 100 uF each for increased ripple current capability, and a 2.2 uF PP to reduce the effects of the high frequency components.
Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
theoretically, half the DC line voltage, but use ones rated at over the DC bus voltage (say 200V ?) to prevent explosions if either of the MOSFETs stay on for too long (we have inherent DC blocking in the design provided the capcitors are rated suitably).
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Patrick wrote ...
I really need that 90 Vdc @ 2 amp one too, my mega (52kv) flyback doesnt want anything more or less it seems.
Im willing to have a slow opto response to regulation error if that means no bizarre oscilations and easier component values in the circuits below. Keep in mind i dont have a network analyzer.
Ok after having been laid off and now re-employed, im returning to this project with a new question. Can an isolation amplifier be used to skip the conventional TL431 / Opto loop, and use a capacitive IC like the Bourns/TI ISO124 to cross the barrier ?
the unwanted oscillatory behavior cant be that fast right ? i mean not in the MHz ? does this IC fade in gain after 250kHz ? im looking at the PDF but need opinions.
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.
Need help with current limiting.
