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On 12/4/18 11:24 PM, Greg Peters wrote:
Hi all,
I know this has been discussed before but forget why it was dismissed. Can
someone remind me?
I think the IGBT approach was found superior -
SCRs are unidirectional, and don't switch very fast.
You'd need back to back SCRs.
Sort of like the use of a hydrogen thyratron (which has also been
tried.. they're fast to turn on, not as fast to quench)
There's also the voltage issue - you'd need to stack them to get the
voltage you need for a NST.
I think that observation is what drove the initial "off line tesla
coils" - using the rectified power line as a several hundred volt DC
bus, then using commercial power semiconductors - I seem to recall that
some folks did start with SCRs, but then IGBTs (which are much faster)
took over, and the rest is history with the DRSSTC - which is
essentially a high power switching power supply with an air core
transformer.
When it gets right down to it, a spark gap is a pretty inexpensive and
decent way to switch high currents at 10s of kV.