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 #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
thanks guys for trying to solace me, but I really consider this one lost. It's much better idea to spend time on something else.
Well if anything, we got some entertainment out of reading about it. I think that bridges could be parallel without problems. Instead of a parallel bridge you could parallel each mostfet and have it as one bridge. I see it in designs here at work on a daily basis. They just love to parallel IRFP450's
Paralleling mosfets directly was my initial intention but then Richie Burnett scared me with stories about parasitic oscillations. So I went the hard way.
You guys may have not realized that I still *don't know* why the coil kept dying. After it worked flawlessly for a month, after some minor upgrades (remote control, tappable primary) it started dying instantly.
It continued dying even after those upgrades were removed, and debugging was extremely hard due to idiotic construction.
I don't know why it suddenly worked after I placed a single bridge in instead of previous two.
Actually, that single one blew once too for no apparent reason.
do you have any figures of power in and power received? Your workmanship is also very nice, and if you had the desire I think you could solve some of your issues creatively.
I never got to measure efficiency properly because coil never had the chance to run without breakout point.
In debugging mania I removed the additional primary winding that was intended to be used to run without streamer load, and never put it back as I was too scared to run without spark anyway.
I just demonstrated it with the spark, at 1..1.5meters I probably pumped like 150W at most while coil was drawing like a 1 kW+. Really just a showpiece and no practical use.
For a "failed" SSTC, I'd say that one worked quite well :)
Well, I had many SSTC's that ''worked quite well'', which consisted of alligator clips and breadboarded circuits dragged across the table - none of which lived for long.
I hoped to have something more permanent, but I didn't even after all the work.
Banned on 3/17/2009. Registered Member #487
Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617
GeordieBoy wrote ...
You work for Sorensen/Elgar yeah? Out of curiosity what is the power rating of the product with the twin'ed bridges using 16x 450's ?
I'd imagine it will make a great CW driver for a coil. Particularly if you can get your hands on the active PFC front-end too :)
-Richie,
Hi Ritchie,
Yes I work for Elgar but we are called Xantrex now. Which is the reason I am looking for a new job. Xantrex is a mess and I am tired of working on fixing thier shitty documentation instead of doing real work. They also screwed up by ditching the Elgar name for Xantrex. Anyway.....
It goes from 1700 to 21kVA. Its and AC power supply and it uses three of the 16 FET modules. You can put a DC bias and do all kinds of weird things with the output wave form. Arbitrary waveforms as well. Here's a link to the supply.
So I have one of the amp modules. Ive been trying to get my hands on a working PFC boost converter board to power it. Then I can try paralleling the bridges. I have a ton of these fixed voltage switchers I might use on it instead.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
Wow, 21kVA! I shudder to think how much that weighs! I've got one of the little Elgar CW supplies here and I can just about lift that off the floor without putting my back out! I'm guessing the new stuff doesn't have the iron transformer though if you can put DC on the output! It's all clever stuff, and interesting too - thanks for the link.
Banned on 3/17/2009. Registered Member #487
Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617
GeordieBoy wrote ...
Wow, 21kVA! I shudder to think how much that weighs! I've got one of the little Elgar CW supplies here and I can just about lift that off the floor without putting my back out! I'm guessing the new stuff doesn't have the iron transformer though if you can put DC on the output! It's all clever stuff, and interesting too - thanks for the link.
-Richie,
No the monster one doesn't have that big fat iron core tranny. Its not a very new design. The boards are all through hole components. There is a lot of boards and separate assemblies that go into that thing. That supply weighs a ton! Never attempted to lift one but the part I have is pretty heavy. It also costs around 18k too! We don't even get discounts.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Dr. Spark wrote ...
Hi Marko,
First your have big balls @ to post “FAILEDâ€
Second, your documentation is stupendous! Good work!
Third, I am always working on 3 or 4 coils at the same time as get pissed and roll one in corner. Coming back later gives me new energy and sometimes looking at a problem over and over again, you will miss something. Take a break for a few months. I am just now ready to hit the Quad VTTC again after Dr. H post.
May I make a few suggestions? Wind a new primary with a bunch of turns to lower the stress on the FET’s. You can always reduce windings giving you more power once things are stable. Also put some space between the turns @ .
Feedback, feedback, feedback. You be surprised how much the fo will change from day to day on a little secondary. Just moving your hand can make a fo shift big time. If the coil is not 100% in tune, the primary will fight the FETs.
Do some FA on the FET’s, that is open one up and look at the die. What is blown? This will allow you to focus on that area like if the gate, look at the over shoot, etc. Use a Dremel tool and take it down in layers. We use rocket fuel (red stuff they mix with O2) to dissolve the plastic. One drop and die is exposed but maybe hard to get.
Good luck, I am sure all will work out if you just take a break.
Cheers, Ch
Hi Dr. Spark, thanks for kind words
Really this one is dead now for like 2 months, and now I began construction of a completely new inverter (much easier than bothering with the thing in this thread) that may be used to drive a SSTC at some point.
Even if I could fix the first one I think it's not right to waste any more time on it.
I've decided that's really better and more practical to have a box with all non-tesla-coil components which I can connect to anything around I want. I've seen people building DRSSTC's in that manner and it seems very practical, plus I'll correct all my mistakes so far.
Changing the PCB's I could even use the inverter for something else like induction heater.
Need though to gather some parts and hope the temperature to drop somewhat so I can work in the garage at all.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Dear Marko, I was full of expectation about your wireless project and remember your notes about some troubles with your SSTC. Now the things are clear… It is a bit ironic that you, a man giving usually most complex and most funded advices and comments failed with H-bridge SSTC – a piece of cake for some of the other members. To make things a bit easier for you, I destroyed my IRFP450 half bridge immediately I plugged it in…I realized that for my crappy designs I need much more robust transistors, mainly higher voltage ratings. No more IRF450 in my live and it is much easier life now…
I wish you good luck with your next design, remember to put your transistors straight (no beds) on FAT piece of aluminum. And keep us updated about your “Marco wireless†progresses
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hi,
my pc is dead so I'll be online less, but thanks for kind words in any case guys.
I was full of expectation about your wireless project and remember your notes about some troubles with your SSTC. Now the things are clear… It is a bit ironic that you, a man giving usually most complex and most funded advices and comments failed with H-bridge SSTC – a piece of cake for some of the other members. To make things a bit easier for you, I destroyed my IRFP450 half bridge immediately I plugged it in…I realized that for my crappy designs I need much more robust transistors, mainly higher voltage ratings. No more IRF450 in my live and it is much easier life now…
Hm, no higher voltage ratings are needed for me as I run only from rectified mains for now. I may use 3 phase power and 1200V IGBT's but only in distant future if everything goes right.
I believe IRFP450's are actually rather solid devices, and I believe they can process lots of power if heatsunking can statisfy their maximum dissipation.
Isolated heatsinks with direct clamp mounting are absolute must if I want to push the devices to end of their rating.
In H bridge each device sees the laod current only half of time so RMS current can effectively be 2x larger than device rating.
If I can get 8 amps at 100C it's still theoretically 5200VA at 325V or 3680VA at 230V (fullwave rectified without filtering). Not sure how much kVA could I get in reality though, and considering SSTC's circulate lots of reactive power the actual real power put into may be some 1500W - but I'd be very happy with that if it could work in reality.
Even more would be possible if voltage is pushed further than mains.
I have started building a new inverter, and would really want to finish it this summer. Going to do the initial work with IRFP450's and only switch to bigger mosfets after the first fail after being pushed *to the end*.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
> In H bridge each device sees the load current only half of time so RMS current can effectively be 2x larger than device rating.
No. The RMS calculation already takes the waveshape into account Marko. It automatically allows for the fact that the current is a half-sinusoid in shape or whatever weird shape the current waveform through a given device happens to be. The RMS current basically tells you the "equivalent DC resistive heating current."
If the device is rated for 8 amps RMS at 100'c junction temperature, that means it is spec'ed to carry a drain current of 8 amps RMS whatever the waveshape.
For what it's worth if an inverter's load current is perfectly sinusoidal, then the peak current can be increased by 41% if only alternate half-cycles are conducted instead of the whole sinewave. This keeps the same RMS current value. It might seem suprising that this is not a factor of two improvement since current is now only flowing for half of the previous time. The average load current does indeed half, but remember that resistive heating is proportional to I squared. That's why the permisable increase in peak current is sqrt(2) and not 2. The RMS calculation takes this into account in its root mean and sqaure operations.
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.
Marko's SSTC
