Re: sstc driver help

["Jan Florian Wagner" <jwagner-at-cc.hut.fi> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Malcolm,

and thanks for your answer!

> > Got some stuff for the SMPS already assembled, but I've a few questions
> > yet. 
> What is its job - to charge a primary capacitor or directly 
> drive the coil?

It's for directly driving the coil, but, with an extra module also giving
the option to charge a tank cap.

> What is the exact topology of your supply? Forward? Flyback? 
> Pushpull? 1/2 bridge? etc. etc.

That's what I'm trying to find out! :o)

Tested half-bridge, lousy results (one FET runs hot, other remains cool,
haven't yet figured out the problem.)

Push-pull with parallel feed gives 900VAC from 12V test-voltage (some sort
of resonant rise I guess, because turns ratio ~ 1:15 would not suggest
that high voltage). But the core starts to hum nastily at the drive
frequency - although it and the wires do not get warm, and neither do the
FETs. Btw, voltage control/feedback is still missing...

Haven't had time to test the other topologies.


I was just curious which topology would be preferrable, taken 500W and
over-sized core, freqs between 100 and 300 kHz, and switching from 220V
line (something around 300V rectified and filtered), and only two FETs?


> > And the last but main question, how do you go about designing the FET
> > snubber network? 
> You have to work out how much energy the network has to get 
> rid of (unused energy, magnetizing energy) 

Thanks, I'll try to work it out!

--
*************************************************
 Jan Florian Wagner
 http://www.hut.fi/~jwagner