Re: MOSFET/IGBT power supply?

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

Original poster: "colin.heath4 by way of Terry Fritz <twftesla-at-qwest-dot-net>" <colin.heath4-at-ntlworld-dot-com>

hi
    the need for smoothing caps is arguable as when run through a six pulse
rectifier. this is the main point of using the six pulse design
the unit leaves you with quite a small amount of ripple as you are only left
with the peaks of the waveform
cheers
colin heath
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, June 20, 2002 6:39 PM
Subject: Re: MOSFET/IGBT power supply?


> Original poster: "Eddie Burwell by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <eburwell-at-columbus.rr-dot-com>
>
> At 08:08 AM 6/20/02 -0600, you wrote:
> >Original poster: "Mr Gregory Peters by way of Terry Fritz
> <twftesla-at-qwest-dot-net>"
>
> <snip>
>
> >Firstly, I would rectify the 240 VAC 3 phase supply using a six pulse
> >rectifier, giving me 340 VDC. I would then switch this using mosfets or
> >igbts at the line frequency (50Hz). Switching would be done using, say,
> >a 555 timer. I would control the RMS current draw by varying the pulse
> >width. This would then be fed to my 10kW single phase pole pig. I guess
> >the core would heat up a bit, but apparently silicon steel isn't too bad
> >at handling a square wave for short periods. Questions:
> >
> >1. Is this possible?
>
> yes
>
> >2. What complications would I run into?
>
> Your DC filter caps would need to be able to handle the ripple current.
> any other problems would be specific to your circuit design.
>
> >3. Can the pole pig really handle a low frequency (50Hz) square wave?
>
> Sure. Square wave will probably have slightly higher core losses than sine
> wave.   For tesla coil duty it should be no problem. You could also up the
> frequency of operation which would allow you to push more power through a
> given core. this would also increase core losses.
>
> >4. Suggestions?
>
> Look at Marco Denicolai's power supply for his project Thor at:
> http://personal.inet.fi/atk/dncmrc/thor.htm
> High frequency switchers have the advantage of being light weight although
> they are more challenging to develop.
> You could use the same series resonant circuit with the pig at a much
lower
> frequency. I would recommend a "soft switching" or resonantly commuted
> design over a "hard switched" design.
> There are so many possibilities that it comes down to the question of
"what
> are your objectives?" Simplicity? Weight? Power? Efficiency? Aesthetics?
> Robustness?
>
>
> Eddie Burwell
>
> >
> >Cheers,
> >
> >Greg Peters
> >Department of Earth Sciences,
> >University of Queensland, Australia
> >Phone: 0402 841 677
> >http://www.geocities-dot-com/gregjpeters
> >
> >
> >
> >
> >
> >
>
>
>
>