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Help appreciated designing (DR)SSTC

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LAN_403

Kakashi

Sat May 20 2017, 01:07PM

Registered Member #61610 Joined: Sat May 13 2017, 09:19AM
Location:
Posts: 4

Hi everyone,
I'm trying to build a DRSSTC or at least (new)SSTC. I wanted to do so for a very long time, nearly gathered all parts but didn't find the time to build it. So now I want to dedicate myself to build one functioning coil. I have immensely read about them all over the net with special accent to Steve Wards pages, Kaizer's and Loneocean's. I have even contacted the guy at Loneoceans about his drsstc designs.
4-5years ago I tried to build a SSTC out of the blue but failed miserably and the coil only worked for like 15secs before blowing all the mosfets. I think it was something similar to ward's SSTC5 if I'm not mistaken just with a different prim/sec.

I have this secondary and primary from the original SSTC I wanted to build, to cut the explaining here is a pic with dimensions and everything:
PIC

The ones with the question mark values, I'm not sure about them since I used simulators,calculators and what not to find their near correct value.

For starters I wanted to go with this type of schematic based of some loneocean's coils. Which I'm not sure if i copied, redrawn it or designed it properly. So correction of mistakes will be much needed.
Schematic

Here are some pics of the secondary coil along with Uzzors fres finder. If i'm not mistaken the fres found is around 220KHz without topload.
Imgur album

So I will need help to design it properly. Is my schematic OK? What type of MMC caps I will need? What about the primary?
Thanks in advance!

Mads Barnkob

Mon May 22 2017, 07:39AM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

The coupling between your primary and secondary looks too high, I would suggest to widen the diameter of the primary coil to get the coupling to be around 0.15-0.2 depending on what performs best for you.

You should use the UD1.3 driver instead of that simple miniSSTC clone to primary feedback driver:

Good MMC capacitors:

MMC calculator:

DRSSTC design guide:

Kakashi

Tue May 23 2017, 09:48PM

Registered Member #61610 Joined: Sat May 13 2017, 09:19AM
Location:
Posts: 4

Mads Barnkob wrote ...

The coupling between your primary and secondary looks too high, I would suggest to widen the diameter of the primary coil to get the coupling to be around 0.15-0.2 depending on what performs best for you.

You should use the UD1.3 driver instead of that simple miniSSTC clone to primary feedback driver:

Good MMC capacitors:

MMC calculator:

DRSSTC design guide:

Thanks for the answer, much appreciated! Now more of my boring questions.

Can you please give me an example of the stated "k" coupling about the primary? An example of how much I need to widen it?
Since the secondary is already made, any proper suggestion on what to begin with the primary side?
I was planing on going half bridge but I do have around 8-10 FGA65N60 IGBT, so should I give it a chance for a full bridge?
Last one. On the steve ward's UD1.3 the small mosfets before the GDT are they really necessary because where I live I can't purchase/find them. Talking about, if I need them for my project, for driving the 65n60. Thanks again

teravolt

Wed May 24 2017, 03:41AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

I am not shore of your skill level and eqipment but the UD2.7 is quit comprehensive with a good description I just bought 2 boards for 12ea

Kakashi

Wed May 24 2017, 01:22PM

Registered Member #61610 Joined: Sat May 13 2017, 09:19AM
Location:
Posts: 4

Yeah, saw that driver also. But I think I will go with steve ward's because it's a bit more simple=nearly the same. I will draw a pcb these days and start from there(also I hate SMD). Another thing, since I can't find those optic receivers/transmitters will some salvaged from old motherboards work?

futurist

Wed May 24 2017, 02:46PM

Registered Member #61400 Joined: Sun Jan 01 2017, 01:01PM
Location:
Posts: 33

I have a spare ST fiber transmitter, receiver and populated UD2.7C board, if you are interested send me PM

I agree on the smd part

Kakashi

Wed May 31 2017, 05:32PM

Registered Member #61610 Joined: Sat May 13 2017, 09:19AM
Location:
Posts: 4

Nearly finished drawing the PCB for the driver. But about those CT/feedback transformers. Will these ones do? link from ebay

Alex Yuan

Wed May 31 2017, 09:33PM

Registered Member #9614 Joined: Mon Jan 14 2013, 10:00PM
Location:
Posts: 44

Those won't work very well, they are designed for 50-60Hz.

I use these for my current transformers:

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