Re: need help igbts welder

On 1 Jun 2006 20:48:11 -0700, kidkv <ZACKSELE@xxxxxxx> wrote:

Ignoramus27153 wrote:
On 31 May 2006 22:12:46 -0700, kidkv <ZACKSELE@xxxxxxx> wrote:

Ignoramus2833 wrote:
On 31 May 2006 21:58:28 -0700, kidkv <ZACKSELE@xxxxxxx> wrote:

kidkv wrote:
Ignoramus11754 wrote:
On 30 May 2006 20:50:59 -0700, kidkv <ZACKSELE@xxxxxxx> wrote:
kidkv wrote:
i have 4 and only need to use two of them and they take 400amps for 1ms
note my welder gos to 225A and the one i got this from does weld with
it hears what he sad from his web site (Just for interest the devices
used in the Alpa test version of the unit were IRG4PC40F (600v 27amp,
these will handle 49 amps in pulsed mode ! 4 pieces were parralleled
for each section of the H bridge.
I later switched to a higher current device G30N60B3D which is good for
600v 60amp (220amp pulsed). Also used was an ultra fast switching diode
to protect the device junctions part number: MUR1540 (600v 15a) ) so
should i take out something or chang out something ???

witch capacitors would br best in it?????


I would suggest Cornell Dubilier snubbing capacitors, like their
series 943.

ok, and what abouth the 470nf caps and the ones on the igbts ??

are those on IGBTs or on the IR2110 gate driver?

IR2110 gate driver C18,17,19,20 are the 470nf and the 1nf caps on
the igbts
ok;-)


You need to read the IR2110 data***. I am surprised that you say
that caps across IGBTs are 1 nf. There is also an application note
explaining some issues if using IGBTs to make inverter welders.

i
i did read the application notes and some more and they both say
something else,
and the caps are on the driver board for the igbts the one that are in
the circut that i am asking abouht are C1 to C16 in the circuit the
application notes say not to use them then one site says to use them
that why i need help on this as take them out or not???
the igbts are the same ones that you had on your first setup;-)) from
the same one on ebay
i know the caps C21,C22,C23,C24 are to stop voltage spikes from
takeing out the igbts


I used different driver boards by Semikron. (also off ebay). These are
very good. They did all I wanted without messing around with
complicated schematic. All I had to build as an oscillator.

Application notes (can be found somewhere on my site) explain how to
calculate snubbing capacitor capacitance. You also need a brief period
when both sides of the bridge conduct.

i

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