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First successful ZVS driver. Yay.

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LAN_403

Inducktion

Sun Jan 30 2011, 08:28PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

I know exactly what you guys are thinking. Oh boy. Another ZVS driver.

Heh. Well, you guys are completely right in your emotions about this overused and overdone thing, but this circuit is the one thing I've managed to build in the past few months that actually works, and works pretty well actually.

Here's a video of it in action if you guys wanna see.

I had actually built this a while back, but it didn't work very well. The arcs were really short and REALLY loud, and it was drawing excessive amounts of amperage from my power supply. So, I kept my eyes open for how to fix this, and found out that I was using a ferrite toroid. Basically, too much inductance caused my ZVS driver to suck. I quickly changed it out for a powdered iron one i had lying around, and WOW. What a difference it made in the arc length! It's so much quieter too, and draws roughly 9.66 amps from my psu. I'm gonna see how big i can get the arcs, the video is only at 12 volts in!
Here's a picture of the actual driver, too.

I know it's not the prettiest thing, but I think I did a pretty snazzy job on it. The mosfet's get pretty warm after a while, the cap, however, doesn't warm up at all. The flyback get's a little toasty too though, at 3+3 turns. It seems to like higher frequency, being that it was from a small TV. I'm really proud of myself for finally getting this thing to work right. ^^

quicksilver

Sun Jan 30 2011, 10:37PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Congratulations on building it and making it work.

However you are the very 1st person have heard from whose MOSFETs got warm! I made several and all of mine were cool (the 'FETs).

I wonder if you would mind telling me if you used the IRFP250, super-fast diodes, and .68uf cap that was standard? I ask because I am curious why you should get warm MOSFETs from a 12v supply at (what; 20A?? more?). I've run about 20 at 35Vdc and still they stayed cool. I did find that they work a heck of a lot better w/ an AC LOPT than the DC however.
To the best of my knowledge the design was made for higher current than 8-10A - so you've got me curious.

Inducktion

Sun Jan 30 2011, 10:45PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

Hm. I used everything i was supposed to use, except for the mosfets xD They're FDL100N50f fets samples from Fairchild Semi. They're good for 100 amps at 500 volts, and their RDS on is .043 ohms. It uses 9.66 amps so...
I don't know what's going on here. Do i need to try and use different mosfets? Their RDS on is lower than the standard ones... Odd.

The inductor also gets slightly warm too, but maybe i just need a bigger heatsink? Or try less windings on the inductor? I have QUITE alot of windings on it, since it's powdered iron. And it's pretty thick gauge enameled wire too...

Edit
Yeah, i think I'm going to reduce my turns on my toroid, i got aLOT of turns on it, way too many looking at everyone else's. I'll post back in a little bit and tell you guys how it did.

Inducktion

Mon Jan 31 2011, 03:39AM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

I changed the turns, didn't really change the performance of it much. The fets still heat up a bit, but i added a fan to it. That seemed to fix it.

MRacerxdl

Tue Feb 01 2011, 01:17AM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Try to increase/decrese the cap in parallel with the primary. One year ago I has this problem too. You should notice increased arc too

quicksilver

Tue Feb 01 2011, 08:39PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Yes, please post a pic. What I had learned is that basically the primary and cap(s) need a degree of "tuning" to get optimum performance. However the level of inductance from the coil may not have as great an impact as the relationship of the "cap to primary" design you've implemented.

The internal schematic of the FDL100N50f differs from the IRFP250: I don't know if this is an issue but it appears there are differences.

Inducktion

Tue Feb 01 2011, 09:03PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

Well, I managed to run it effectively all the way up to 32 volts, and the fets stayed warm with the fan on them. I was getting really big arcs, at about 9-10 amps flowing through it.

Also, what do you mean they differ?

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