Designing HV transformers.

I'd love to get a copy of that amazing pile you've gathered. My mailbox has no overall limits that I'm aware of, although I usually don't go much over 10MB per email message, to be safe.

I can put the pile on our ftp server, for others, if you like. My email is, ahem, hill-atthingie-rowland-dot-org

Win & others,

Mebart has begun sending me his data, and I'll stick it on a web site after I get it all and have bundled it up.

---Joel

But this is less of an issue at higher frequencies.

Thanks Win. Why is space less of an issue at higher frequencies? I presume you mean less of an issue for insulation/arcing but I can't see why.

... or are replaced by unwanted resonances and capacitive losses. Distance is Good!

If it's not that hard to send it to my email address, I'd certainly appreciate it. My curiosity is at a fever pitch.

If they're plain text, they zip up amazingly well. I wouldn't be surprised to see 40 MB of plain text (or even HTML) compress to under

Cheers! Rich

OK, I will forward them to you, all the messages are under 9 mb, some are much smaller.

Over the years, you've been a pretty mellow type-can't imagine a fever pitch in Win's house.

Standby for massive email.......

OK, I moved some of the atachments and files around, so forwarding the message sent previously to Joel won't work as the files can't be found by the email program.

It will take me awhile as I will have to hunt down everything and try to keep from sending too many duplicate files.

I'll get the files out of the old archive and start with them. The newer archive is scattered and will take a little longer to sort out.

Regards,

Thanks Rich,

They are mostly pdf's with a few gifs and a few word files........they won't compress well.

Regards,

Care to elaborate ?

Graham

I really look to getting those email packages. Just change the spelling by adding a w, to rowland, and we should be all set.

Win, I have 5 email message ready to send to you with the data. I did find a few of the files I was missing when I snet the info to Joel. Namely, a very nice close up picture of a PZT showing both sides and the original 1999 article in EDN that inspired me to look for sources of these parts and to learn about them.

I sent you a short test message to your un-munged email address to make sure I had decoded it ok, but didn't get a reply.

I used 000h0ill 0at0 0roland00 d0ot or0g, take out the 0's to un-munge.

Hope you received the test email, if so, just drop me a line saying you got it and I'll let those emails fly.

Regards,

OK, that explains why you didn't reply to the test message, glad I waited to confirm I had your address right.

wroland looks good to me.

standby.

Hah! OK, got it all, what a haul, thanks! Should I post this mass of great stuff to our ftp server?

By the time you read this, you should be able to download "PiezoXfrmr.zip" from

---Joel

Sure,

When I designed HV transformers, I found that above about 3 kV, the majority of the problems with losses, corona, ringing and so on are caused by inter-winding capacitance and capacitive coupling to the core.

Winding the secondary with all layers in the same direction and rectifiers inbetween layers make almost all the trouble go away. The voltage builds up as you get away from the core. The interwinding capacitances can then help filtering and the voltage swings at the end of the windings will be in the same direction, i.e. zero between windings.

Like:

-------D|---------------> HV | =

-------D|------ --| | =

-------D|------ --| | =

To get this to work, you need long, single layer, windings; i.e. Thin Wire and good distance to the core at the ends of the windings. So the triple insulation does not help - it displaces Air with material with higher capacitance, putting more stress on the remaining air gaps. You get corona.

A special former split into multiple "disc" sections will also work, provided they are "stacked" like shown. Those are easier to wind, but the formers and cores that match them are hard to get in quantities below 200000 ;-)

Resonant converters help a lot because they have lower rise times so less capacitive current will flow and you transformer will have loads of leakage anyway that it would be a shame to fight against.

Finally, you probably want to keep switching frequency low, 25-30 kHz maybe - the creepage distance is what dimensions the core so you are not going to beat the conference circut with 1 MW/cm3 anyway.

PS:

If it really has to be cheap and you do not mind cheating, a modern Ignition Coil for a Car can typically deliver about 40 W at 12 Kv when driven from a single end resonant converter. Flyback works too at less efficiency.

Boss didn't like that particular solution because Customer would spot the obvious COTS part and begin to worry about what he should really pay for the unit - which would not be good because the price tag was about 70 times the cost ab factory!!

"Cash Flow from Financing" ... i.e. pension money from propellerheads buying the stock for their retirement!

I can't help but notice the domain of your email address though. I sure wish I could afford to buy all the technical references in your org's stockpile-I'd be like a kid in a candy store.

I'd want anything to do with piezo power generation, and with cockcroft-walton based power supply design and simulations. You have a nice paper in there about simulations on photomultiplier tubes too.

Anyway, all the stuff I gathered was public domain on the web, searched out with google. Enjoy.

If you are looking for sources for the actual devices, I'll send you info about a US suppliers I know of.

Joel has just archived the data in an 18 mb zip file, can you download it all at once via the web? If not, let me know and I'll gladly email all the files.

If you have www access, check out his ftp site. Download "piezoXfrmr.zip" from

Please keep me posted if you actaully start playing with them.

Regards,