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From: "Frithiof Andreas Jensen"
Subject: Sv: 8KW DC buck-converter
Date: Sun, 5 Jan 2003 19:23:13 +0100
X-Newsreader: Microsoft Outlook Express 5.00.2615.200
Organization: TDC Internet
Jon Starr skrev i en
> Hi everyone,
> I have recently had the good fortune to acquire an 'Innova 90' krypton
> ion laser, but my problem is that this beast wants ~35 Amps at 208V!
This is a difficult design!
> current peaks from the mains (single phase) so I need some sort of
> slew rate limiting I assume.
I doubt you can run this off single-phase; the "best" I have seen is the
"cooker-connection" in the UK rated at 35 A. You will need more.
The simplest is probably a 3-phase SCR rectifier bridge followed by a linear
regulator. The SCR bridge can regulate the voltage down to perhaps 215 V and
then a "standard" linear series regulator can control the current. There are
3-phase controller modules available as building blocks. I suggest this
because the usual capacitive filter is useless without Power Factor
Correction - the L/C filter used with an SCR bridge will cause a bit of
inductive load, but not much.
Use IGBT's or MOSFETS instead of bipolar for the series regulator - they are
much more robust in case the current control loop transiently will shut the
series regulator almost off, leaving a large voltage & current across the
I would imagine that this could happen when the tube first turns on. The
loop may be hard to stabilise too.
> with the design I'm doing as I don't want to melt my laser through an
You should worry more about melting yourself or the wiring in your house ;-)
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