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>

i agree robert
                    sorry iwas getting the wrong end of the stick there if
the caps are just for filtering
cheers
colin

----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, June 21, 2002 6:45 PM
Subject: Re: MOSFET/IGBT power supply?


> Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<rheidlebaugh-at-zialink-dot-com>
>
> Colin: your comments are quite correct, I do however wish to add a small
bit
> of councel. Past all rectifiers had in addition to capacitive filtering a
> choke (coil) in series to protect the rectifiers from surge current. With
> robusk solid state devices the size of the coil is reduced, but I still
hold
> to the consept of using a choke in serirs with rectifiers to protect them
> from current surges. Protection is often cheeper than repair.
>   Robert  H
>
> > From: "Tesla list" <tesla-at-pupman-dot-com>
> > Date: Fri, 21 Jun 2002 07:57:21 -0600
> > To: tesla-at-pupman-dot-com
> > Subject: Re: MOSFET/IGBT power supply?
> > Resent-From: tesla-at-pupman-dot-com
> > Resent-Date: Fri, 21 Jun 2002 07:58:47 -0600
> >
> > 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
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >>
> >
> >
> >
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