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 #347
Joined: Sat Mar 25 2006, 08:26AM
Location: Vancouver, Canada
Posts: 106
Hi All,
I just completed a schematic and PCB layout for a DRSSTC power board, and I'd like your opinion on it. I'm building my first DRSSTC and I'm trying to come up with the most bulletproof power board possible.
I've tried to go with common, cheap parts as much as possible, and used SMT parts to save space and keep inductance down. I plan to have the board made with 4oz copper, as opposed to the normal 1oz thickness.
This full bridge uses 5 TO-247 IGBTs in parallel as each switch element, to allow the use of cheap IGBTs, and give a high peak current rating. I'm thinking of using HGTG20N60A4D IGBTs which are rated 600V 280A maximum pulse, for a bridge rating of 1400A max without exceeding datasheet spec. These cost about $4.73 each. The board has room for terminal strips to allow easy IGBT replacement.
I've opted to go for many small parallel bus capacitors for low internal resistance and good heat dissipation (large surface area to volume ratio) The main bus cap will be 30 of either 150uF 400V or 100uF 450V KXG series from United Chemi-con.
There are some MCX RF connector jacks installed to provide easy and accurate measurements of the low side gate drives and the outputs, using MCX-BNC and BNC-scope probe adapters.
The schematic and board layouts are in PDF format below.
-Is the inductance of the HF current loop from the bus caps, through the IGBTs, and back to the bus caps low enough?
-If the above inductance is low enough, are TVSs necessary?
-Will the electrolytics have low enough ESL to allow operation without other capacitors? I've made provisions for 20 x 500V 0.22uF SMT ceramic caps Those caps are expensive and I'd like to avoid using them if possible.
-Will GDTs be suitable? Each 5 IGBT bank has a Qg of about 1uC. I'm thinking one GDT on each half bridge.
-Will shoot though be a problem with the individual gate resistors on each IGBT? Those are there to prevent oscillations that can occur when directly paralleling gates.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
I think that paralleling 5 IGBTs is too big piece of cake... I made a lot of experiments of paralleling the IGBTs in a single switch design and the power peak you can switch is not following the linear additive function. I personally think that three transitors is the rational maximum unless you have very precisly matched components (including resitors). Otherwise you can use the GDT for all three (or five?) transitors, the limiting factor is rather in the gate drive. There are few schematics for really powerful gate drivers around this board... Good luck with your project - It looks very attractive
BTW: Always use the TVS! - they are cheap and can save a lot...
Registered Member #347
Joined: Sat Mar 25 2006, 08:26AM
Location: Vancouver, Canada
Posts: 106
Hi Mates,
I was thinking that the ZCS of a primary current feedback DRSSTC would help with any imbalances during switching by allowing the switching to occur at relatively low current, hopefully completely within the rating of 1 IGBT. Was the application you were referring to with parallel IGBTs ZCS or hard switched?
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
tesla500 wrote ...
Hi Mates,
I was thinking that the ZCS of a primary current feedback DRSSTC would help with any imbalances during switching by allowing the switching to occur at relatively low current, hopefully completely within the rating of 1 IGBT. Was the application you were referring to with parallel IGBTs ZCS or hard switched?
David
Once you are able to keep the system all the time close to ZCS than you can parallel IGBT's without limits... But driving 5 gates in parallel will be challenge - I would go for min 30A, 20V per five transitors, each gate its own resitor and zeners. You should also find some rather big toroids for your GDT's. Otherwise, your scheme and PCBs proposals look great. I'm thinking of using it for my own future projects - good job. Good luck...
Registered Member #1024
Joined: Sun Sept 23 2007, 10:56AM
Location: Northern NSW, Australia
Posts: 95
nice layout If I was to change anything I would make the gate tracks thicker and try to extend the emitter tracks underneath them, but really it looks good. I have a few tubes of those 20n60's so I may well put one of your boards together! I would probably add some big poly caps instead of the expensive ceramic smt's. And I would probably drive the gates with one or two big gdt's wound with shielded audio cable, and driven with a descreet driver for good power. Anyway looks very good,let us know how it goes!
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.