120V monstrous ZVS driver for custom flyback transformer / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

120V monstrous ZVS driver for custom flyback transformer

1 2 next

Move Thread

LAN_403

Chris Cristini

Wed Apr 15 2009, 09:22PM

Registered Member #1749 Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497

This is just an idea but if you use large anough mosfet's and make a huge flyback transformer with like 20 winds on the primary and as many winds on the secondary with reasonable thickness wire to handle huge amounts of power at very high voltage. It may be hard to rectify and smooth all that current but it would put out a nice arc im sure.

Proud Mary

Wed Apr 15 2009, 10:12PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

In domestic television use, line output transformers (US: 'flybacks') are normally operated at around 115V.

Chris Cristini

Wed Apr 15 2009, 10:29PM

Registered Member #1749 Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497

Wow I did not know they ran at that voltage in TV.s I always thought they were ran at 20V or so. I mean like this

but at 120V at a couple of Amp's

Mike

Wed Apr 15 2009, 10:45PM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

the problem with flybacks is when you drive to very high levels the secondary begins to arc over inside and eventually just melt. if you use thick enough wire to stop this from happening you wont get nearly as high voltage output as you would with the tiny magnet wire that is normally used.

Myke

Wed Apr 15 2009, 11:07PM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

One problem with the ZVS flyback driver is that as you increase the voltage input to the driver, it becomes harder and harder to aviod parasitic oscillations. That's why most people use other driver topologies at high powers.

Big MOSFETs tend to have large gate capacitances and so to keep the MOSFETs out of the linear range of operation as much as possible, you would need to decrease the resistance of the pull up resistors. You could also lower the oscillating freq so that the tine the MOSFET is in linear operation is kept a small percentage of the cycle.

Arcing shouldn't be a problem if you make your own secondary because you can pretty much make the insulation as thick as you want. You would need some filler insulator to prevent corona at high voltages though.

Chris Cristini

Wed Apr 15 2009, 11:08PM

Registered Member #1749 Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497

Well can't you make your own on a bigger core and put it all in transformer oil and maybe the driver to?

Note. I need to obtain a large variac don't want to just plug things in.

Mike

Thu Apr 16 2009, 12:27AM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

I think if you want to have some fun make one of those full bridge resonant drivers and just destroy a couple flybacks. I have seen a few threads on the forums of people pulling foot long arcs out of flybacks before killing them!

Firefox

Thu Apr 16 2009, 12:52AM

Registered Member #1389 Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346

I think once you pass the point (50-80Vin) when it is tough to keep paracitic oscillations out of the ZVS driver, the SLR topology becomes superior. While the ZVS flyback driver can pull massive currents at low voltages (tough with the SLR topo), limiting current draw becomes the problem at higher voltages, which the SLR topokogy does by nature.

Chris Cristini

Thu Apr 16 2009, 02:03AM

Registered Member #1749 Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497

Firefox wrote ...

I think once you pass the point (50-80Vin) when it is tough to keep paracitic oscillations out of the ZVS driver, the SLR topology becomes superior. While the ZVS flyback driver can pull massive currents at low voltages (tough with the SLR topo), limiting current draw becomes the problem at higher voltages, which the SLR topokogy does by nature.

SLR topology?

Arcstarter

Thu Apr 16 2009, 02:07AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Firefox seems to have hit it head on. That sounds about right. The current would indeed be insane. Also, the mosfets would have to be good. I have seen a 120 mains powered zvs sstc though. Exact same schematic.... Not sure whats up with that but the sparks where about a foot or something.

1 2 next

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