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 #1960
Joined: Thu Feb 05 2009, 11:57PM
Location:
Posts: 48
Long time lurker, first time poster - hello 4hv!
After reading the interwebs many resources about induction heating (IH), I've decided to realize my own.
I'll use a AVR microprocessor with a Allegro ACS756 current sensor(yes, it's a bit overkill(capable of 200A)). Basically I'll start high and tune the frequency down - and this way achieve pll similar operation. I intend it to stay in the inductive load region slighly above resonance. My goal is that it will constantly dither between resonance and 1-2% over resonance. IE: decrease frequency until current goes up - and down (meaning that it's in the capacitive region); then tune a bit up to. If current changes, start over or take action to protect everything. The uP will work as a pll (while not actually doing 'true' pll). A simple timer-interrupt vect toggling a pin will give me fine resolution tuneability.
I'm using a half bridge driver with tristated input and programmable deadtime. I have not decided mosfets yet, I'm a bit tempted to try PQFN dualcool. I have access to cnc pcb machining equipment, time to try it!
The plan is to rectify mains. Maximum power will be 2kW. Power controll will be done by detuning, but it will be tuned to run at maximum power at resonance.
I have 100x these 1,8uF capacitors. I would like to use them, but their capacitance seems a bit on the high side. Would a suitable compromise be to make the work coil low inductance - to get the frequency out of the audible range? And secondly, are these caps really rated for this use. When checking datasheets dV/dt they seem unsuitable. Anyone have recommendations for my tank setup, I would highly appreciate it!
Registered Member #3888
Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649
Hello and welcome.
Since you already have the capacitors they might be worth a shot. Worst case scenario you fry a few of them. Since they do have a high capacitance and are less robust then what many people use (metallized polypropylene) you should use a bunch of them in paralleled series strings to get your desired capacitance.
Having so many to work with should also help you narrow down the capacitance value that works best before you replace them (should you need/want to.) I think the electrical connections should be made close to the capacitor so that you don't have a ton of stray inductance in your mmc, but you could probably leave the rest of the capacitor lead in place so that you could reuse the caps (again, should you choose to replace them later)
Registered Member #1960
Joined: Thu Feb 05 2009, 11:57PM
Location:
Posts: 48
Thank you :) yes, coupling them in series and then parallell is an obvious solution. I'll do that and start off with 6 in series - with 5 parallell strings. 30 caps total, should give some surface area xD 1.5uF and I'm aiming for a 3-4uH inductor would net me ~65kHz operating freq, and that is suitable.
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.
Lclr induction heater. uP pll. Questions about design.
