Re: Solid state TC progress ?

To: tesla-at-pupman-dot-com
Subject: Re: Solid state TC progress ?
From: Alan Sharp <AlanSharp-at-compuserve-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sat, 01 May 1999 22:46:34 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Message text written by INTERNET:tesla-at-pupman-dot-com
>Change topology: use full-bridge and a series resonant design.<

Thanks Marco - I've got a book! 

I've looked at this but I've got a few questions. 
How do I calculate the leakage induction? Is there a voltage rise accross
the primary? What controller chip are you using? What size of transformer
are you using to switch 5kW at 50kHz? Why does toast land butter side down?

I also wondered about dispensing with the output xformer all together
and feeding the coil of a resonant LC.

Your design sounds like a great project - do keep us posted.

Alan Sharp (UK)

A couple of days ago I have been feeding a test inductor at 50 kHz with
300V DC
and sinusoidal current peaking at 3 A. As I switch at zero current and zero
voltage, my IGBTs stay cool. More, as the current shapes are all
sinusoidal,
there are no switching spikes and ringing losses as long as you switch at
the
right moment. I calculated that switching 5 kW each IGBT will dissipate
about 4
W (!). At full power I am going to use 560 VDC and 12.5 A max.

A resonant series design basically features a capacitor in series with the
transformer primary. The capacitor and the transformer leakage inductance
define
the resonance frequency and the maximum current the primary will sink.

You'll find more about it on swithcing power supplies textbooks.