RE: Strange Half-Bridge Heat?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

 >when I hook the GDT up to the half bridge the tracks of the source
 >and gate heat up. The 10 ohm resistors in series with the gate heat
 >up as well. Anyhow, at the same time the UCC37321 and UCC37322 chips heat
 >up terribly (but only when connected to the half bridge)

Don't worry, this is normal behaviour ;) Driving the gates of large FETs or
IGBTs at high frequency uses a lot of power, and all of this power is
dissipated as heat in the gate resistors and driver chips. (The FET gate
can't actually consume power because it's a capacitance.) There should be no
problem unless the UCC chips actually die from overheating.

I have an H-bridge of 30A IGBTs on my bench at the moment, driven at 120kHz
by two UCC37321/2 chips. The UCCs get too hot to touch, limiting runtime to
about a minute. I am using 10 ohm 1/4 watt gate resistors and these get hot
too.

This is intended for a small ISSTC, though, and once I install the
interrupter everything should run a lot cooler, as the gate driver is turned
off 95% of the time.

Steve C.