Re: SCR power supply (fwd)

---------- Forwarded message ----------
Date: Sun, 18 Jan 1998 19:13:10 -0800
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: SCR power supply (fwd)

> To All
> A while back I ran across a book on induction furnaces. In the book was a
> short discussion on using SCR's in a circut like a multivibrator  to
> provide power for an induction furnace. The book was vague about the
> circuitry involved but it did allude to a circuit that (1) provided back
> EMF to shut off the SCR and (2) provide a trigger pulse to fire the SCR
> the oppsite polarity. 

My GE Xray machine power supply uses a pair of high power SCR's to make a
500 Hz inverter at 100 Amps, 100 V.  It's pretty simple. The center tap of
the transformer primary is connected to one side of the power. The SCR's
switch the alternate sides of the transformer to the other side of the
power. A capacitor across the whole winding provides energy for
commutation. I am grossly oversimplifying here. If you email me your fax #
or snail mail address, I'll send you the schematic.

 don't know what the upper frequency limit for tis
> type of circut is, 

limited by the commutation speed of the SCRs and the magnetics of the
circuit, i.e. low (a few kHz at most)

>but I'm thinking that it may be a way of generating
> power at high enough frequency to make it cost effictive for us coilers
> a budget. If any of you have run across this application, any information
> would be helpful.....Thanx               Al Syme   KG0QJ

Check the archives for the notes on the solid state inverter drivers some
people have been working on. Gangs of FETs in parallel.....