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 #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Hi all
EDIT: this is without interrupter connected. Just tried with it, still excessive regulator heating.
Today I got the time to sit down and test the driver ( ) I built after Steve's schematics ( ) , with a few changes that might have had some impact.
Instead of the Infineon SPB18P06P MOSFET, I used ST IRF9540 MOSFET and viceversa for the N channel part, they are about even in characteristics except that the IRF9/540 MOSFET have about 3 times as high gate charge.
The driver is connected to a GDT that is connected to a half bridge of IGBTs
I left out the LM311 IC as I have no CT to connect at the moment, plugged a LED to the OCD indicator to see if it kicked in during runs, it did not.
There is no heating to be noticed on any MOSFET, IC or regulators... except that the 24V regulator supplying the MOSFET stage is about to catch fire in seconds.
I have thought about the following causes of this excessive heating on the regulator:
MOSFETs cross conducting and thus shorting the supply, waveforms shows there is dead time and little ringing
24V regulators capacitor is fine, 330uF, measures 348uF. No shorts over the 24V rails.
voltage on the 24V regulator is measured to 0,7V HINT! something is wrong, but somehow I doubt that the 12V supply to the MOSFET driver ic is coupling 5Vp-p through the MOSFETs to the GDT.
The feedback signal is a function generator running a square wave at 60kHz, 10Vp-p
Here are my waveforms, request more if needed
Gate waveforms
Gate waveforms zoomed on the rise/fall
GDT secondary vs feedback input signal
GDT primary vs feedback input signal, those peaks looks nasty
Registered Member #2040
Joined: Fri Mar 20 2009, 10:13PM
Location: Fairfax VA
Posts: 180
You should test it without any drive signal to narrow the problem down.
I'm wondering if you have enough turns on your GDT, or if you have the right core? You can try increasing the drive frequency to see if that reduces current draw.
On the last picture you have: "GDT primary vs feedback input signal," which one is which?
Completely unrelated, I noticed that you have a rigol scope. I just got their 100MHz model and it seems decent so far. How do you like yours?
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Z28Fistergod wrote ...
You should test it without any drive signal to narrow the problem down.
I'm wondering if you have enough turns on your GDT, or if you have the right core? You can try increasing the drive frequency to see if that reduces current draw.
On the last picture you have: "GDT primary vs feedback input signal," which one is which?
Completely unrelated, I noticed that you have a rigol scope. I just got their 100MHz model and it seems decent so far. How do you like yours?
I have tried with the GDT made for my medium DRSSTC, its 10T on a 50 mm diameter 5MHz core, i calculated a minimum of 5 turns for that core to avoid saturation, and another GDT with 15T on a smaller 25 mm diameter core that drspark sent me a while back.
First mentioned signal is on channel 1 and so forth
I have had the 50MHz Rigol DS1052E for a month or two now, I have just been too busy to sit down with the manual and get through all the stuff it can, but what I really like is the fast updating lcd display, compared to older expensive DSO, this is really fast! The measurements menu is also a good friend, get everything in an instant. Auto button is also nice if you just have to check something fast, the scope seems sturdy and the construction / finish is just as good as what i would expect from a more expensive scope. The PC software seems a little shady, not sure exactly where the benefit of it is now as a screencapture goes the wrong way in my mind, I want to click on my scope to save a waveform and then be able to download it to the pc, but its done from the pc which makes it a hazzle when doing some measurements.
Registered Member #2040
Joined: Fri Mar 20 2009, 10:13PM
Location: Fairfax VA
Posts: 180
I see what you mean about the voltage across the GDT primary:
"voltage on the 24V regulator is measured to 0,7V"
Just to be sure, I noticed on the scope that the range does not automatically adjust for the probe attenuation factor. So is it possible that you had the scope set up for a 1X probe while the probe was actually set to 10X? Meaning that you really had 7V across the primary?
What is the current rating on the regulator? Is it possible that you are drawing too much? I see that these waveforms are without the interruptor, have you rechecked the waveforms with the interruptor?
You have one picture showing "gate waveforms" at ~12V p-p, and another showing "GDT secondary" at 1.5 p-p. I'm guessing that the "gate waveforms" are for the GDT drive circuit and not the actual IGBT halfbridge?
That's good to hear that the rigols don't explode after a few days; makes me feel better about spending so much The only thing I want to complain about is that it wont work with my USB drive. I'm not sure why yet, but hopefully it won't be too much hassle to figure out.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Z28Fistergod wrote ...
I see what you mean about the voltage across the GDT primary:
"voltage on the 24V regulator is measured to 0,7V"
Just to be sure, I noticed on the scope that the range does not automatically adjust for the probe attenuation factor. So is it possible that you had the scope set up for a 1X probe while the probe was actually set to 10X? Meaning that you really had 7V across the primary?
They are set for 10x both on the probe and scope
Z28Fistergod wrote ...
What is the current rating on the regulator? Is it possible that you are drawing too much? I see that these waveforms are without the interruptor, have you rechecked the waveforms with the interruptor?
They are bought as 24V 1.5A ST L7824CV regulators from china
I have measured the current through it to peak at 1.3A and then it shuts down, so I am drawing too much current, I will have to find a alternative 24VDC source.
I still fail to see the course of this huge power consumption, the only difference from steves design are other MOSFETs and lower value decoupling caps in series with the GDT, the GDT is pretty much standard 10T with cat5e cable on a 5MHz core.
I have tried with interupter on and at 300 kHz, makes no difference
Z28Fistergod wrote ...
You have one picture showing "gate waveforms" at ~12V p-p, and another showing "GDT secondary" at 1.5 p-p. I'm guessing that the "gate waveforms" are for the GDT drive circuit and not the actual IGBT halfbridge?
Gate waveforms are as you say the gates of the MOSFETs driving the GDT, GDT secondary would be the gates of the IGBTs
Registered Member #2040
Joined: Fri Mar 20 2009, 10:13PM
Location: Fairfax VA
Posts: 180
The IGBTs aren't blown are they?
That amount of current is a clear indicator that something else is wrong. I used bricks in my DRSSTC and although I didn't measue the current, the 1A regulator never gets more than luke warm. If I had to throw out a conservative guess I'd say it should be well below 0.5A.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
The bridge is made from brand new IGBTs originial ST 30N60s
GDT driver MOSFETs are IRF(9)540 and I have measured no shorts on them.
I just checked the gate at one of the IGBTs, signal is fine at 300 kHz, but only 4.8Vp-p, could be some of the MOSFETs in the GDT driver stage is not tip top, I will look into this when I get time.
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.
Steve Wards new DRSSTC driver debugging
The only thing I want to complain about is that it wont work with my USB drive. I'm not sure why yet, but hopefully it won't be too much hassle to figure out.