Welcome
Username or Email:

Password:


Missing Code




[ ]
[ ]
Online
  • Guests: 124
  • Members: 0
  • Newest Member: omjtest
  • Most ever online: 396
    Guests: 396, Members: 0 on 12 Jan : 12:51
Members Birthdays:
One birthday today, congrats!
modularduck (49)


Next birthdays
02/19 EDY19 (37)
02/19 rp181 (31)
02/19 Digital Chaos (41)
Contact
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.
Forums
4hv.org :: Forums :: Tesla Coils
« Previous topic | Next topic »   

DRSSTC Voltage

Move Thread LAN_403
alan sailer
Sat Feb 24 2018, 11:30PM Print
alan sailer Registered Member #59110 Joined: Mon Apr 11 2016, 04:35PM
Location: Camarillo, California
Posts: 74
I am making steady progress on a QCW project and have a beginner question about voltage waveform.

I got the DRSSTC part of the project running a while back and it looks good. The driver is loneoceans UD2.7
board and it's working very well. I used the inductor to tune the coil for ZVS operation and the waveforms
show very little overshoot when tuned correctly.

My question has to do with the voltage waveform (Collector to Emitter) after the interrupter turns off.
The voltage excursions after the interrupter turns off (and the tank current starts ringing down) are much
higher than any during the on time. I have seen this on other DRSSTC waveforms on this forum.on these.
So far I'm only running about 90 volts on the buss, but the voltage can go 10-20% higher than this during
the ring down period.

This is not a problem at the low voltage I'm currently testing at but could be an issue at higher voltage.
The only way to avoid the problem would be to use a fairly high voltage TVS. I notice that some designs
use them, others not. And I can't figure out why.

Cheers.
1519514826 59110 FT0 Dsc08788


Note: The voltage waveform was taken with a diff probe and has an effective scale of 100 V/div.
Back to top
Hydron
Sun Feb 25 2018, 10:28AM
Hydron Registered Member #30656 Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208
Your waveform looks very normal (infact it looks extremely clean!).

Some increase in bus voltage is expected (the energy left in the system when the interrupter turns off is returning to the bus capacitors, charging them up), but I do not know either why the ringdown sometimes has large spikes.

I would not any TVS diodes until you look at behaviour at higher bus voltages - you may find that the spikes get no worse as the voltage is increased. TVS diodes aren't a magic solution either - it's hard to specify them to not conduct during normal operation but to clamp at a low enough voltage to reduce high-energy spikes to safe levels.
Back to top
alan sailer
Sun Feb 25 2018, 03:17PM
alan sailer Registered Member #59110 Joined: Mon Apr 11 2016, 04:35PM
Location: Camarillo, California
Posts: 74
Thanks.

It is good to get your assessment of TVS. I was looking at the specs and they are (obviously) far from ideal devices.

I am also kind of surprised at how nice the wave-forms are. I keep thinking that I am missing something. The most
interesting thing that I noted was that the phase tuning got rid of the overshoot over the entire interrupter pulse.
All of the scope shots I found on these forums had minimal overshoot at peak current but more at the beginning of the pulse.

I'll bet that things will start to uglify when I get higher in voltage.

Cheers.
Back to top
Hydron
Sun Feb 25 2018, 06:34PM
Hydron Registered Member #30656 Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208
One thing I would check is whether the scope is capturing at a high enough sample rate to catch narrow spikes. I'm assuming that you've zoomed in a bit more than is shown in the screencap you attached and still not seen overshoot, but I do know that those old tek scopes are rather limited in memory depth (and thus sample rate at slower time/div settings).

I would be interested in more details about the coil, especially which IGBTs you're using.
Back to top
alan sailer
Sun Feb 25 2018, 08:16PM
alan sailer Registered Member #59110 Joined: Mon Apr 11 2016, 04:35PM
Location: Camarillo, California
Posts: 74
Yes I have zoomed in. Thanks for checking. It is an old Tektronics 60MHz/1Gs/sec.
In the past I've looked at ~10nsec pulses from an LED/photodiode so it should be fast enough.

I wish I could say my design is original but I'm cloning almost exactly loneoceans QCW 1.0.
I'm using his UD2.7 and the EasyBridge which uses paralleled IRGP50B60PD1 devices.

Since I hate programming I'm attempting to generate the ramp with an analog input
using ideas from another coiler. So far it's moving along fine. I'm in no particular hurry.

Cheers.



Back to top

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob

Go to:

Powered by e107 Forum System
 
Legal Information
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.