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ZVS philosophical question

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Xray

Tue Feb 01 2011, 05:33AM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

I've read many posts from guys researching, designing, and building a ZVS circuit. After spending a lot of money, and countless hours on making the stupid thing work, they make sparks and arcs with it and then post a 5-minute video on YouTube drawing an arc between a wire and a grounded alligator clip. Why?

Microwatt

Tue Feb 01 2011, 05:55AM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
Location:
Posts: 224

becuase its a pissing contest.

Patrick

Tue Feb 01 2011, 05:57AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Microwatt wrote ...

becuase its a pissing contest.

Yes, I think thats it.

Ash Small

Tue Feb 01 2011, 06:10AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

For the same reason that people build Tesla coils.

I'm currently researching to build a >3kW HV supply. I'll probably try push-pull and Mazilli ZVS topology to drive the transformer(s). (For Mazilli topology I'll have the four 'U' cores arranged in an 'E' core formation, for push-pull I may arrange them as two 'U' core pairs and run at a higher frequency.)

It should produce some pretty big arcs either way.

It's a 'stepping stone' on the 'learning curve', as is the single transistor driver.

You may as well ask 'Why do philatelists collect stamps?'

Patrick

Tue Feb 01 2011, 07:45AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Ash Small wrote ...

For the same reason that people build Tesla coils.

Yeah but Tesla coiling really matters, ZVS'ing is just for cowards and pansies.

Coronafix

Tue Feb 01 2011, 07:54AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Not all of them post videos of the arcs they make.
Some post pictures of the things they destroy with the arcs.

I thought that was bloody funny.

Steve Conner

Tue Feb 01 2011, 10:11AM

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

Ash Small wrote ...

You may as well ask 'Why do philatelists collect stamps?'

Because they (we?) have no life?

Xray doesn't understand, because if he wants some enormous flaming arcs he can just grab an X-ray transformer from the heap in the corner. Using the forklift if necessary.

Or, working with HV for a living, he sees it as a powerful tool to be respected, rather than an exciting and dangerous toy.

Ash, the Mazzilli topology is a strange choice for 3kW. The original Mazzilli circuit worked with 1200V IGBTs and drove a Tesla coil, but I've never seen another one like that. The successful hobbyist-built HV power supplies I've seen mostly end up as SLRs driven by a full bridge. The original model for this is Marco Denicolai's Thor CCPS, which was simplified and improved by Steve Ward:

He was blowing lots of FETs using the ordinary resonant topology, and I think it was me who persuaded him to try the SLR. He also invented those neat single-layer secondaries, which I thought were a great idea.

Ash Small

Tue Feb 01 2011, 10:33AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Steve, I was considering SLR H-bridge topology and I read Marco's website and Steve Ward's website but it was pointed out to me that it is difficult to regulate the current using this topology as you can't use PWM.

I realise the Mazilli driver has similar drawbacks, and that is how I arrived at push-pull topology (I can't really see how an H-bridge would be a better option if using hard switching).

I may well end up ditching the current regulation and end up with SLR H-bridge topology, but it makes sense to experiment with simpler topologies first as I'm still relatively new to this game.

Thanks for your opinions, though. (Any advice regarding current regulation using SLR topology will be appreciated.)

Dr. Dark Current

Tue Feb 01 2011, 10:35AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Because the arcs look cool.
And I've learned the basics of power electronics and switching supplies on them.

Steve Conner

Tue Feb 01 2011, 10:45AM

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

Ash: The whole point of the SLR is that it is current limited by design. You can happily short the output and pull arcs off it. The Mazzilli is actually worse in that respect.

Dr. kV: That is the idea. Kids nowadays have no attention span, and a huge host of multimedia gadgets competing for it. If the race of engineers isn't to die out, we have to bribe them with cool looking arcs, to force them to learn stuff.

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