Odin The All-Fragger: a large DRSSTC / Projects / Forums

Forums

4hv.org :: Forums :: Projects

« Previous topic | Next topic »

Odin The All-Fragger: a large DRSSTC

first previous 3 4 5 6 next last

Move Thread

LAN_403

ragnar

Mon Jun 19 2006, 10:31AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

I've had really good experience with those "tall donuts" / ferrite sleeves... but then again even free common-mode chokes give better performance/waveforms than ferrite I pay good money for ^^

Silkscreen... pshh. I don't even print out my schematics or overlays when assembling my boards... which might explain why I blow so much stuff up

hehehe

Besides, it makes commercial obfuscation more straightforward... second to grinding chipnumbers and the black epoxy, that is.

I just loooove the bipolar* drive! Sexy waveforms! What kind of charge/capacitance are we talking here?

*I know it's deliberately 2/3----1/3

Steve Conner

Sat Jun 24 2006, 09:47PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

It's a CM600HA-24H IGBT brick so the gate charge is about 5000nC, I think.

Today I took the single turn primary off the OLTC2 resonator and replaced it with 9 turns of 1/4" copper tubing. It could probably do with somewhat more, but 9 was all I could fit while still keeping good clearances.

I also managed to drop the resonator onto a concrete floor, breaking the secondary wire in about 3 places and shearing off half the nylon screws that hold the lid on.

Marko

Sat Jun 24 2006, 09:59PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I also managed to drop the resonator onto a concrete floor

poor resonator..
I hate when this happens, I just recently burned a hole (from inside) in my DRSSTC secondary, just from pure carelessnes with toroid connection wire.
Now that part has bulged and is crispy to touch

So you are going to completely 're-use' OLTC 2 as a DRSSTC.
Sounds cool.

-me sees steve posting in 'attachments'
PS. OMG just saw it

Steve Conner

Sat Jul 08 2006, 12:46PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yea, it's coming on slowly. I'm going to do more work on the frame tomorrow, and try to get the gate driver boards finished today. I'll try and post a pic of me wielding the finished coil a la Sam Barros for old time's sake

Marko

Sat Jul 08 2006, 01:00PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

looks pretty good to me.
Are you currently using conel or helical primary?

I also had problems with primary coils, and pipe I had was so degenerated that I had lots of places where turns touched mutually.
I had to use solid 2,7mm wire wich now makes trouble limmiting the primary current

It seems that only hope is to buy already wound pipe and just roll it 'as is' on there.

Primary from your MjÃ¶llnir looked pretty good, I like the style how is it 'pressed' between columns and inner pipe.

Hazmatt_(The Underdog)

Sat Jul 08 2006, 06:39PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

If you have space issues with 1/4" why not get 1/8" Copper tubeing or 3/16". It's an easy answer you know!

And don't come back with "well yea..but the current is going to heat it up really fast" So! you're going to all this trouble with everything, just put a circulator in the system with a small pump.

GimpyJoe

Sat Jul 08 2006, 10:59PM

Registered Member #316 Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212

He's saying (I think) that the pipe he had was bent around and had been used for other things before he wound a primary with it so it had bumps and kinks in it. And I don't care how much current you have, it's still gonna be hard to heat up 1/8" copper pipe enough to need cooling

Marko

Sun Jul 09 2006, 12:20AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Steve Conner wrote ...

omg updatez @ scopeboy.com

Hehe, always been my favourite site, keep it going

I'm pretty sure that copper pipe if it was 'used' cannot be wound nicely anymore, no matter how much you heat or punish it.

If it isn't already 'in roll' it's very hard to bend it into desired shape.

Steve Conner

Sun Jul 09 2006, 04:50PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Omg updatez!

Hazmatt: I hope it won't come to needing water cooling. :-/ The spark output of this coil is probably going to be limited by how much power I can get at venues, so I want it to be efficient. If I can only get say 32A@240V, that's 6kVA or about 4kW, and I don't really want to waste one of those kilowatts making tea.

Firkragg: Yes I reused the copper tubing from my old Tesla-2 primary, and I wish I hadn't.

I had to scrap the "inner pipe" part of the Mjollnir primary, this new page explains

Steve Ward

Mon Jul 10 2006, 12:03AM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Looking great Steve.

I dont know that 1/4" copper tube will handle the power... it will probably get piping hot at even 4kW. When i run my coil at 5kW for awhile, even the 2awg wiring gets quite warm. I recently replaced every connection that was made from steel hardware with brass... the steel was getting absurdly hot.

I also recently figured out why my coil blew up twice recently. I thought it was a voltage spike issue, but it really turned out to be that my old gate driver design floated the output HI when it lost power, and i happened to be running the control circuits on the same 240V feed. So after a few minutes of exceeding my 20A breaker, it would trip, then all the IGBT would blow up from shoot-through on the rails. My new gate driver doesnt have this problem and is also a far better driver.

What i did find in the end is that the little film decoupling caps dont really help much for voltage spikes, provided you keep the lytics connected to the IGBTs with a laminated bus structure. In the end i did end up using RCD snubbers across the IGBTs, which helped the voltage spiking, but i dont think the spikes harm the IGBTs anyway

.

Really looking forward to the end result Steve!

first previous 3 4 5 6 next last

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