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Triggering Stacked IGBTs



Original poster: "S&JY" <youngs@xxxxxxxxx>


I am looking for ideas on practical and not overly expensive ways to trigger a stack of IGBTs. For example 10 1,200 volt IGBTs in series to take the place of a spark gap.

The SISG (SIDACs) scheme is good, but I want more control. I would like to be able to externally vary pulse rep rate, pulse width and the DC voltage to the stack independently. I suppose I am after a poor-man's variant of a klystron modulator such as used in particle accelerators.

One method is to use fiber optic coupling to photo detectors controlling each IGBT. I have read these are susceptible to electrical noise. Other methods use pulse transformers, e.g. modulated several mHz inputs and rectify the outputs to control the gate. Or use pairs of pulse transformers to trigger a flip flop on and off to control the IGBT gate. Of course, whatever scheme is used must trigger all the gates simultaneously. And the trigger circuits on the IGBT side must derive their power from the main DC power to the IGBT stack (to avoid the need for isolated power supplies).

Can some of you steer me to a source of ideas? Better yet, can any of you report your practical experience triggering series connected IGBTs?

Thanks,

--Steve Y.