[Larken]

I think you need to add an inductor (on the high side) to give the circuit some charge time. The way it is now the current rises so fast that the current sense circuit isn't fast enough.
Do you have a (very fast) sense circuit that shuts the gate drive off when the current reaches a set peak ? Without it, it will definitly blow.

Also you should lower the 100 ohm res to about 10 ohms and make sure your drive circuit can output a clean 15 volt square wave with lots of current.

Those mosfets arn't designed for repetative high current abuse, get some newer ones that are.

I see you are grounding the work with the live output of the fets, Is you 63volt power supply isolated ?

[Blaugen]

dear friend: I have the same problem. see my posts on Mosfet driver signal generator - Page 2

[neilw20]

I have not tried this circuit yet, but it certainly has promise.
At first the circuit is a little confusing, but if you join the names with lines it starts to make sense.
You must closely observe proper connection techniques for this circuit as voltage drops in the wires, inductive and resistive, will fry the MOSFETs with great abandon.
With out referring to the IRF data sheets for the driver chips or design knowledge in this are will most likely create the odd bit of $smoke.
Easy to get out, hard to get back in again.

[wildwestpat]

There are number of physical conditions that need to be taken into account if you are going to operate power MOSFETs in parallel. Use separate resistors for each device i.e no common sharing of components.

Ideally the devices should be matched at the current used. Yes there are a load of commercial designs that use parallel operated power devices but these will almost certainly be from the same die.

There are useful papers to be found by Googling operating power MOSFETS in parallel from which this is a general summary.

http://www.ixyspower.com/images/tech...s/IXAN0058.pdf

And

http://www.fairchildsemi.com/an/AN/AN-558.pdf

are relevant to this thread.

Hope this helps. Regards - Pat

[Blaugen]

I have a solution for a part of the circuit, which is the current limit resistor: I bought a threaded ceramic core and wind around a first winding on a sense of the double of ohms and another in the other sense (in antiparallel) over the first. Thus I created an antiinductive charge. It is a little, but it is something.

[Blaugen]

If you have circuits, especially with pulse generators, please upload! I finish my first EDM 5 years ago (its building takes me 3 years), it is a Lazarenko type (with RC oscillator) and runs well, but it’s just a metal disintegrator, now I wanna make a better machine. In my last post, when I said charge I meant load. sorry my grammar, I'm not american. a hug.