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Protecting IGBT's

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Zeus

Fri Nov 06 2009, 04:05AM

Registered Member #2316 Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107

I was just given 4 20N60s and I want to make a ZVS driver. However I do not want
to wreck them.
I have considered neon globes, zener diodes but I have settled on blocking diodes.
Also transorbs have caught my eye and I can get them from TV sets.
This will be my first ZVS so I would like some advice.

Patrick

Fri Nov 06 2009, 05:38AM

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

Hello,

Hmm, yes i like TVS diodes but you need a spec-out one (not a salvadge one) from Collector to Emittter, remember the clamping must be below your max transsitors voltage, but above your max supply voltage. then you may want a small one across the Gate to Emitter (but with the lowest capacitence you can find, other wise the capacitence might load or delay your gate drive.

But really i thing you need to buy a whole bunch of semiconductors for your high side, in my experience you will blow stuff up in the
experimental/developemental phase, then when you get it all figured out its pretty reliable, steve wards site is a good primer.

expect to lose parts in a shower of sparks...

Also, i like the To-247 case. its better then the To-220, but not as expensive a mini-brick.(its good to start with low or medium power for the To-247's, then learn enough to move up to the mini-bricks for mucho kW power)

-patrick

Zeus

Fri Nov 06 2009, 11:11PM

Registered Member #2316 Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107

Thanks for your reply. My 20N60s are TO-247 and I have a stupendous heatsink.
My budget is limited, so any semiconductors I have are salvaged.
I don't want to let the magic smoke out of the IGBTs.
I hope to have a good supply of them from plasma TVs PSU.

Firefox

Sat Nov 07 2009, 12:02AM

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

I've been doing alot of experimenting with the ZVS flyback driver lately and can tell you that there are a few specific things that kill my IGBTs in my ZVS. First, make sure your input inductors do not saturate, this will kill your IGBTs right quick. Make sure any wire in the circuit is appropriate for the current passing through it. Any short circuit in your circuit will release either your filter cap's or your input inductor's (or both) energy into your IGBTs, probably killing them. If your tank cap short circuits, both IGBTs will turn on and again, they will likely die from the filter cap's energy being released into them. If you haven't guessed, I've learned these lessons the hard way

Patrick

Sat Nov 07 2009, 02:14AM

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

Hmmm, if you are limited by what you can find, then you need to use alldatasheet.com to find datasheets for your desoldered TVS's. but first, check Mouser.com for existing datasheets, make sure you understand the constants and values enumerated in the docs. you need to know about the knee curve and your operating conditions, volts, secondes, power, time constants, partial clamp, full clamp etc... And now what all that means .

i use the STmicro Transil's 1500 watts for the collector to emmiter, then i use the 600 watt ones for gate to emitter pins, put them as close as possible to the to-247 case. the 600 watt ones have less capacitence. too much capacitence may disturb your gate drive wave signal(depending on hoW you generate your timing)

I hope you can do this with out losing your only 4 IGBTs but i am skeptical. be ready to by more.(if you blow them 2 at a time)

-Patrick

Zeus

Mon Nov 09 2009, 12:08PM

Registered Member #2316 Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107

Buy IGBTs? Methinks not, as I said I can get heaps of them.

Patrick

Mon Nov 09 2009, 11:09PM

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

And who / where is this source from which IGBTs magically sprout from?
in anycase if you have more then youre fine...

Zeus

Tue Nov 10 2009, 10:18PM

Registered Member #2316 Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107

A TV repair shop.

Patrick

Wed Nov 11 2009, 03:15AM

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

in your first post it sounded like you only had 4, but if you have a supplier of many then go for it, you will blow some out, but you must see and learn sooner or later.

-Patrick

Zeus

Wed Nov 11 2009, 04:08AM

Registered Member #2316 Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107

At that point I only had 4 now I will have more.

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