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
Pinky's Brain wrote ...
AFAICS the snubber transfers the energy from the primary leakage induction to the snubber capacitor when the MOSFET turns off (it doesn't keep ringing of course, I was wrong about that). When the MOSFET turns on the capacitor starts a partial oscillation with the inductor, initially the voltage at the right side of the capacitor will be negative, when it rings up with the inductor they can dump energy in the main power supply smoothing capacitor (ie. regeneration).
excellent, ill try to simulate all this then, ZVS and ZCS are what im trying to use to ease the burden on my square wave switching MOSFET/PPCT transformers too.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
You sure you want the headaches of ZVS/ZCS? The control schemes are not fixed frequency, and the standard ICs for them schemes aren't designed for transformers as lousy as high voltage transformers.
One way to reduce stress on the MOSFET is two switch flyback, Jan Martis's design is very elegant but to work it has to increase Vds above the power supply voltage. With a two switch design you can keep Vds at the same value as your power supply voltage.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Pinky's Brain wrote ...
You sure you want the headaches of ZVS/ZCS? The control schemes are not fixed frequency, and the standard ICs for them schemes aren't designed for transformers as lousy as high voltage transformers.
One way to reduce stress on the MOSFET is two switch flyback, Jan Martis's design is very elegant but to work it has to increase Vds above the power supply voltage. With a two switch design you can keep Vds at the same value as your power supply voltage.
when i say ZCS/ZVS i mean making sure the voltage and curretn arnt present at the same time while the switching transsistions are occurring. i absolutley dont want to get into sine wave stuff.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
I am trying to do the math on a current transformer, id like to use a single wire pass through for the primary (as i see many of you SSTC'ers do with your bridges) so do i consider this kind of primary a 1/2 turn?
ive been reading the TI/Unitrode stuff here -> but it doesnt say in this case.
im trying for a 40kHz, single switch forward waveform current detection.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
What EXACTLY do you mean with soft switching? I thought you merely meant slow switching since you want to avoid resonance.
AFAICS this isn't what your reference means when it says soft switching, it means using something like a resonant snubber or active circuit to achieve ZVS ... evil sine waves.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Pinky's Brain wrote ...
What EXACTLY do you mean with soft switching?
I want to use soft switching to reduce MOSFET heating. When i say ZVS/ZVC i dont mean a resonant circuit. I mean the voltage and current are not present at the same time, first one rises then the other, or first one falls then the other, having both V and I cross while the resistance is in the "linear" state it where most transistor heating comes from.
The switching times should change from off to on in the shortest time period possible.
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.
HV Flyback Bench Top Power Supply for Lab.
