Re: SSTC idea - DRSSTC ?

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

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 18:06 31/03/03 -0700, you wrote:
>Original poster: "jimmy hynes by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><chunkyboy86-at-yahoo-dot-com>
>
>
>Hello Jan,
>
>Thanks for the comments, I've been thinking along the same lines.
>
>Earlier, I tried using one driver chip per transformer with a capacitor do 
>remove the DC bias

As far as I know, you only need one gate drive transformer for your entire 
H-bridge, even if you're using dead time. If you allow the gates to be 
driven with +/- 30V or whatever, then the input waveform to the GDT will be 
symmetrical. You use a full-bridge (two driver chips) to drive the GDT, and 
during the deadtimes you set both arms of the bridge to the same state, 
thus imposing zero voltage across the GDT and turning all the IGBTs off. 
You still use a DC blocking capacitor, but the mean voltage across it is 
zero so you don't have to worry about transient stuff.

A commercial controller chip like the TL494, or its more popular relative 
the 3525 (widely second-sourced, can be UC3525, KA3525, LM3525, SG3525, 
etc) would take care of all the deadtime/drive signal generation stuff for 
you (See TL494 Feedback SSTC schemos on www.hvguy-dot-com for inspiration) then 
you could use a 555 timer to set the burst length, and you wouldn't have to 
worry about trashing any more microcontrollers ;)

Steve C.