Re: An SSTC simulation

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

Original poster: a a <hermantoothrot2000-at-yahoo-dot-com> 

Hi,

In your simulations, does the voltage across C8 drop back to zero at the 
secondary voltage peak?

I had thought about discharging the capacitor, but decided against it 
because the current it would have to withstand. You could get away with 
much less energy storage, which is good, but the rms current would be too 
high. In my current design, you can keep adding capacitors in parrallel, so 
even cruddy capacitors will work if you have enough.

Right now I have 40 1000uf 200v (10000uf 400v) capacitors for energy 
storage, but I think they may be the limiting factor in my design.

The average driving voltage is also less, so you need a little more current 
for the same power, but that is a minor point.

I had also thought about dynamic tuning, but decided against it because of 
simplicity. It is very easy to manually find the resonant frequency if you 
are using an oscilloscope while it is running, but I don't know if you can 
do it otherwise. You still have to mess around with the tap point on the 
primary to get the right tuning there.

Why such a high coupling and high frequency? You can get away with more 
transfer time, and it is easier on your MOSFETs. I used 8 cycles (K~0.12) 
at 60khz, and still got some pretty good results. I think IGBTs would be a 
better choice for this too. One IRG4PC40W would be better than your 6 
MOSFETs at any current above 35amps.

If you find some capacitors that can stand completely discharging 60 times 
a second, then it would probably be a better way of doing things.

Tesla list <tesla-at-pupman-dot-com> wrote:
Original poster: Kchdlh-at-aol-dot-com

In a message dated 11/7/03 7:23:20 AM Pacific Standard Time,
tesla-at-pupman-dot-com writes:


 >Subj:Re: An SSTC simulation
 >Date:11/7/03 7:23:20 AM Pacific Standard Time
 >From:tesla-at-pupman-dot-com
 >To:tesla-at-pupman-dot-com
 >Sent from the Internet
 >
 >
 >
 >Original poster: "Dan Strother"
 >
 >If I understand your circuit correctly, this looks similar to Jimmy Hynes'
 >DRSSTC (http://www.hot-streamer-dot-com/chunkyboy86/ ), in that it uses a set
 >of IGBTs/MOSFETs to dump energy into a loosely coupled, tuned primary coil.
 >Thus slowly transferring a large amount of energy into the secondary coil
 >(and, hopefully, matching a conventional SGTC's performance). Would I be
 >correct in this analysis?
 >
 >
 >Dan Strother
 >
 >
 >
 > >Original poster: "K. C. Herrick"
 >*snip*
 >
 > >So..-dot-comments, anyone?
 > >
 > >Ken Herrick
 > >
 >


Fundamentally, yes: series-resonant primary, parallel-resonant
secondary. But my scheme a) uses resonant storage-capacitor charging while
Jimmy's does not and b) incorporates "dynamic" control of the
tuning. Also, I don't believe Jimmy's storage capacitors are necessarily
fully discharged every mains cycle. So perhaps they'd last a whole lot longer!

In regard to my amplifying circuit, I'd like to point out something I just
realized. There's no need to have the U1 EX-OR in the circuit: regardless
of the phasing between primary and secondary, feedback will be positive
during one of the two mains half-cycles; doesn't matter which one.

Just slap any old secondary onto it and it will! take off!

Ken



Jimmy