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 #3964
Joined: Thu Jun 23 2011, 03:23AM
Location: Valenzuela City
Posts: 332
ben123324 wrote ...
Fjust to correct what I see as a misconception in this thread. ALL capacitors "snub". The only thing hat dictates how well the do so is how fast they can accept charge, which directly translates to current. You could use anything from 20nF to 2mF, it all depends on the use. The benefit of small capacitors(the 2-20uF usually used) are that they can be physically close to the device.
To put in another way, if you want to snub 1J of transient energy, a 10u cap may see a voltage rise of 20v, where for the same energy transfer a 100u snubber may only rise 2v. These numbers are made up, but you should see what I am saying.
If you could fit a high current 100uf cap as close to the bridge as you could a 1u, then it would be preferred. But the main limiting factor is pulse current, so find a decent metalized film cap that can be close enough to the bridge.
I agree, but the poster looks tired on finding good cap. and also, we want to let him practice correct snubbing installation and technique by insisting him to put the caps as close as the switches so 10uf should do. The capacitors he posted are MKP (but for audio apps) But i think it will work reliably since those caps are exactly what I use and like his situation, those are the only caps available on my place.
Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
But you also have to keep in mind that with he mosfets he uses, snubbing isn't as critical as igbts may require because irfp's can avalanche. But I Also will say that snubbing can never hurt(at least in most situations) so if you don't know whether or not you need to, use them by default.
Another option that can be cosidered are tvs diodes. They accomplish the same goal, but they heat up if too much energy is dumped. Using them along with snubbers will render your bridge pretty much transientproof.
Registered Member #3964
Joined: Thu Jun 23 2011, 03:23AM
Location: Valenzuela City
Posts: 332
As I have said earlier, The guy needs some help/hints =) as EE's we design for more than the requirements and also space for future developments (DRSSTC) , that's why we encourage to let him use whatever can help him even it is over rated, when we look at the bridge, its obvious that there are plenty of room for transient to build up. Yes, fets has avalanche rating, but when he try to replace it or develop it into a DRSSTC, im sure those IGBT will blow once he put higher power. TVS are very good snubbing choice, but sometimes, finding it is a more difficult task than finding caps. I agree to use it both whenever available, as it is also my practice on my bridge.
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.
Low output and mosfets burn
