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RE: Dan's ISSTCII help

Original poster: "Mccauley, Daniel H" <daniel.h.mccauley@xxxxxxxx>


Sounds like either the following:

1)  Duty cycle is higher than what you think it is for the gate drivers
    (I assume your gate driver ICs were hot???)

2)  The gate transformers might not be designed properly etc...
(saturating which is causing the
    gate drive ICs to burn up)


>After many fits and starts I finally fired up the ISSTCII.
>I sequence the startup as follows: Turn on the pulse generator
>which is a
>remote box, Turn on the power to the driver board, lastly
>slowly increase
>the AC voltage to the IGBT power supply. Everything seemed to be going
>well. I had the IGBT DC bus voltage at about 100 volts and was
>varying the
>pulse width and prf controls about 10% up from minimum. The
>arcs at this
>point were well over 12" and the controls were functioning
>normally. After
>about a minute the arcs began to decrease in intensity and I
>shut down the high voltage. Nevertheless the 37321 drivers
>fried. Right now
>it does not appear that the IGBTs fried but a full
>investigation can not be
>done until tomorrow. There are still normal drive pulses
>through to the
>37321 sockets.
>The +5, -15 and +15 supplies are all nominal. Drive pulses to
>the IGBTs
>were about 30v. I do not have a terminating resistor at
>present in the base
>feedback circuit.
>My question to anyone with experience with Dan's unit...Has anyone
>experienced this failure at such a low voltage on the IGBTs
>and if so did
>you figure out what happened?
>Thanks for any and all comments
>Skip Greiner