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.
Ive got it working, I put 10k ohms where Hen918 suggested.
4.6uS @ 5.1 volts
14.4uS @ 2.8 volts
Vref = 5.1 volts
It does vary linearly with the turn of the potentiometer. Now I need to pick some exact values, and really get the design formalized for a new etch.
EDIT: pics
EDIT: It appears when I put 1.3 volts on pin 9 ( ILM/SD ) the PWM pins, both drop to zero. so I guess I don't know what "pulse-by-pulse current limiting" means.
Edit : ill be using the IGBT : ]hgtg7n60a4d.pdf[/file] and switching 170 Vdc through the primary, at no more than 4 amps.
Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
The control loop of the current limiting is causing it to drop the pwm to 0: When you apply over one volt, the controller drops the pwm, and keeps dropping it until the current voltage goes below 1 volt. If you are keeping the voltage at 1.3V, the controller will rapidly drop the pulse width all the way to zero until the over current voltage is dropped.
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
Hmmmmh. IGBT @ 170V ?
Supose your 4A is the peak current. If the current was rectangular then you IGBT will have Vcesat(4A)=1.8V. What loss in a Mosfet equates to 450mOhm Rsdon. This is quite bad. If you assume a triangular current waveform the Mosfet is even better due to quadratic dependence on the current instead of nearly linear like the IGBT.
Looking at Digikey, Searching for Single Mosfets, "Vds>200V", "Ids>6A", "Rsdon < 400mOhm" and "THT" then entering the quantity of "1" and sorting for price you get a variety of alternatives that seem so much more suited for your project..... I case you cant follow my parametric search, then i just name a few: FQP19N20C (94ct, 170mOhm, 200V, 19A, TO220) RCX200N20 (110ct, 130mOhm, 200V, 20A, TO220) FDP18N20F (114ct, 145mOhm, 200V, 18A, TO220) STF20N20 (120ct, 125mOhm, 200V, 18A, TO220) FDP39N20 (132ct, 66mOhm, 200V, 39A, TO220) FDP33N25 (144ct, 94mOhm, 250V, 33A, To220) ..List continues. I just picked the ones that are much more better than your IGBT. (since i only searched for Rsdon<450mOhm.. should have searched for Rsdon<150mOhm)
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
DerAlbi wrote ...
Hmmmmh. IGBT @ 170V ?
Supose your 4A is the peak current. If the current was rectangular then you IGBT will have Vcesat(4A)=1.8V. What loss in a Mosfet equates to 450mOhm Rsdon. This is quite bad. If you assume a triangular current waveform the Mosfet is even better due to quadratic dependence on the current instead of nearly linear like the IGBT.
Looking at Digikey, Searching for Single Mosfets, "Vds>200V", "Ids>6A", "Rsdon < 400mOhm" and "THT" then entering the quantity of "1" and sorting for price you get a variety of alternatives that seem so much more suited for your project..... I case you cant follow my parametric search, then i just name a few: FQP19N20C (94ct, 170mOhm, 200V, 19A, TO220) RCX200N20 (110ct, 130mOhm, 200V, 20A, TO220) FDP18N20F (114ct, 145mOhm, 200V, 18A, TO220) STF20N20 (120ct, 125mOhm, 200V, 18A, TO220) FDP39N20 (132ct, 66mOhm, 200V, 39A, TO220) FDP33N25 (144ct, 94mOhm, 250V, 33A, To220) ..List continues. I just picked the ones that are much more better than your IGBT. (since i only searched for Rsdon<450mOhm.. should have searched for Rsdon<150mOhm)
I figured someone would say this. I just used the 7 amp and 30 amp versions since I have 30 of one and 40 of the other. there is a really good MOSFET I used at 30 volts and less. Which eventually this power supply will work off of at 12-18 volts input at 20+ amps.
EDIT: The voltage varies linearly from 0 - 0.7 after .7 it jumps to 1.25 V. below the .7 the PWM is off entirely. above the 1.25 its on. I also have to keep the pin 9 below 5 volts or it will blow out.
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
For an analog loop you should avoid PushPull-Outputstages like the PC911L0YSZ. Easy solutions like the PS2561-1 is fine. You could try it with SFH6345 , but i dont see much reason there. HCPL7520 is surely interesting.. but i honestly think its overkill.
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
Actually they are quite complex if you want to get them right. It is however easy to get something working. It depends on what kind of control loop you want to implement. If its kind of digital like "start switching" when voltage is low or "stop switchting" when voltage is high enough then its easy. but its most likely inefficient, produces high ripple under constant load conditions and... yeah.. its basically nothing else than a most primitive over voltage protection. A real analog loop also controls how much energy is transfered when switching. Such a loop can be too slow to be optimal, produce overshoots if too fast or it even can oscillate. Its in no way trivial, but often it just works somehow (most likely when its made really slow). As long as you dont care to make it optimal, its can be easy.
Thats why i propose the PS2561-1. The Push-Pull-Output has too much loop-gain (making it digital oscillating). The SFH6345 just adds complexity to the loop and the HCPL7520 might even have not enough gain. Just try.
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.
Need help with current limiting.
I just used the 7 amp and 30 amp versions since I have 30 of one and 40 of the other. there is a really good MOSFET I used at 30 volts and less. Which eventually this power supply will work off of at 12-18 volts input at 20+ amps. 
