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 #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
Regarding I started this new thread because I no longer think my problem lies with the gate driver. Glad to report a bit of success for me as well. Below is the new board entirely inspired by the self resonant driver board by EVR, pretty much all of the layout is copied with respect to the gate driver layout and power supply, I kept the primary feedback inputs at the bottom left (the 4 blue terminals on left) which gave me plenty of room to put the IC's in the middle and route everything nicely.. There is an added hex inverter not shown here, meant to invert the incoming signal from the FO since that was also an issue I had before.
--
Above is the Pulse at the igbt gates. much better then before, rise time is about 144us with no 'roll' anymore, just a little overshoot. I am also using the 10uF tantalum for DC blocking and no longer having problems with that anymore. --
These wave forms taken at the output of the gate drivers are with ONLY the interrupter on as well as GDT/half bridge connected (when unconnected it is normal). I was given the impression that this is not normal though. I got something similar to this with the old board, which is partially why I dont think my problem lies with the gate drivers anymore, I've cleared that problem up with the new layout. Once the signal from the signal generator is in place it seems to go back to normal (which is good), whereas with my old board the feedback signal would follow that waveform resulting in very messy drive. Hours of extensive searching around the board and tracing all the signals and I've concluded there are no wrong connections, solder shorts, or bad solder joints. I put my heart and soul into this board after the problems I had with my last few boards and there definitely has been progress. -- I am thinking now that if this is a problem, It must lie in my GDT design because I only get this waveform with the GDT and half bridge section connected to my board. Here are a few pics of the half bridge section as well
As you can see this is also copied artwork from EVR. GDT core is also from EVR.
I initially thought that this waveform was the interrupter start-up pulse. I'm pretty much stuck here, has anyone seen something like this before? suggestions please...
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
I assume the first wave form photo is without anything attached to the gate drivers? What does the wave for look like with just the GDT connected (nothing else on the H-bridge)? So connecting leads across the two secondary wires that would go to the gate of the IGBT? how long are the primary leads on the GDT? I kept mine under 2" to avoid stray inductive effects. Also - what does the gate-emitter wave form look like (doing a differential measurement) at the IGBT?
Trying to see if it helps to slowly connect one component at a time and see what the response is to identify where it starts falling apart.
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
Bushman wrote ...
I assume the first wave form photo is without anything attached to the gate drivers? What does the wave for look like with just the GDT connected (nothing else on the H-bridge)? So connecting leads across the two secondary wires that would go to the gate of the IGBT? how long are the primary leads on the GDT? I kept mine under 2" to avoid stray inductive effects. Also - what does the gate-emitter wave form look like (doing a differential measurement) at the IGBT?
Trying to see if it helps to slowly connect one component at a time and see what the response is to identify where it starts falling apart.
First waveform is at the gates of the igbt's. Both interrupter and signal generator on .Only one half bridge section is connected. Zooming out would show it more normal, sharp rise and fall, flat tops with a bit of overshoot.. Unfortunately the pdf manual for my oscilloscope has incorrect instructions on how to take differential measurement. It is impossible to change the v/div when using the CH1+CH2 function, it just stays at 100nV so I can't see a darn thing. What I do is just take the differential measurement anyways and then use the measurements functions to acquire what I need. From that information it seems normal. Sharp rise times, about +25ish and -25ish volts (in a perfect situation it would be +-20, the extra +-5 is the overshoots). The primaries are longer than 2 inches but pretty tightly twisted. I guess I'll trim them down and see. I've seen Many setups with GDT primaries more than twice the size of mine I just never thought mine were causing this particular problem.
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
If that first waveform is at the gate with the IGBTs installed, it looks pretty good. So if I understand, when the interrupter is running this is what you see at the gate, but the gate driver signal is then messed up - correct? What is the gate driver signal like when the H-bridge is not connected? Is each of the channels connected to a single Gate Driver? I see you have double up the driver ICs - what happens if you try with just 2 ICs (one inverting and one non-inverting)?
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
I have double up drivers because i will be running on fullbridge using two half bridge sections. Rather than attach a bunch more scope pics, i think i will make a short video going through all the connections with scope shots. That way you can see exactly what is connected and such. I will post the video tonight when I can make it.
See this for a moment and take note of that first waveform that is of the interrupter only, it looks silly like mine. And a few people mentioned that it is just the GDT core saturating to start oscillations. How is this different from what I am experiencing?
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
If that is just the core saturating (it does look similar to yours) yet the waveform at the gate looks good when the feedback is connected, why is it an issue? I guess I am a little confused as to what exactly is the problem? Sorry, I can be slow sometimes
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
Well honestly I do not know if it is an Issue or not. When I got this waveform on my other board which i posted here , EVR said "Your middle waveform looks really funky. I've never seen that before. I think you have something else going on somewhere. Maybe something really simply like a solder short or incorrect connection - i don't know. And probably because of this is why the 10uF tantalum isn't working out for you." and I trust his judgement. My difference now is that I do not have problems with the yellow tantalum capacitor or regulator heating anymore, all those issues are gone. But yet I still get this funky waveform. I can spend all day tracing the signals all throughout the circuit and everything is completely normal, up until I connect a GDT. And like i mentioned before I've spent a long time going over every connection and making sure there are no solder shorts/bridges between traces, no cold solder joints.. And I even tried 3 different core types to see if that made a difference, it did not. Heres info on the other two cores, the green is fair-rite 77 and the blue is epcos N87, info for the core from EVR can be found in his site.
Here is the video by the way And for some reason when I scoped the igbt gates this time around they were all messy, but the the other day it was looking just fine. EVR was probably right, I got to have a bad solder connection somewhere, either that or bad component. Although I've used all new components each time I made a board. Might have to spend all weekend re-doing any suspicious looking solder joints
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
The video was very helpful. Which lead is connected to the IC with the Dc blocking cap - the yellow or the blue trace? Strange that only one signal is messed up. The second and third GDTs you used seemed a lot better. I do not recall if I check my driver output with just the interrupter running - always had a feedback signal. Later today I will hook up the scope and try and duplicate your setup and see what I get. Our circuits are very similar so if I get the same signal, we know my coil works so it may not be an issue. Before you go re-solder everything at least I'll be back !
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
Ummm I think it was the yellow trace I had connected to DC blocking because the interrupt signal initially is present only on the return side when the GDT is not connected which is why the blue trace would show the signal. Then when I connect the GDT, the yellow trace on DC blocking side shows the silly wave. I very much appreciate you trying to duplicate results, that would very helpful!! Also now that I think of it I remember specifically that the signal came through the DC blocking capacitor on one occasion but after a few seconds it went away and the blue trace went normal. I think that may suggest a bad capacitor or bad solder joint. At this point I am trying random tests with different value caps and even adding low value resistor in parallel on occasion, in efforts to try and clean up the waveform. So far with little success. I want to keep the design as close to original scheme as possible since changes should not be necessary..
Registered Member #4146
Joined: Tue Oct 18 2011, 02:01AM
Location: Wisconsin, U.S.A
Posts: 56
I could be wrong but i think your signal looks messed up when only the interrupter is going because the gdt is designed for the frequency of the of the feedback signal not the interrupter frequency and that is why when you have both signals going its it looks better if that makes any sense.
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.
IGBT signals problem
and there definitely has been progress.
