Jeremy,
Most DRSSTC builders go to ebay to find used IGBT modules for TC use, this
is why the CM300DY-24H became so popular, they have been on the surplus
market steadily for years. When they first hit ebay i was buying them for
just $10 each, but now days expect to pay about $50 per module. They are
considerably slower switching than the APT module so you would likely want
to keep the TC resonant frequency <100khz. I should also note that the
CM300 appears to be one of the most rugged "300A" modules ever, they just
dont make them like that anymore. Nowdays, IGBT manufacturers are claiming
higher current ratings on less Si, and that means we cant abuse the parts
as much.
The only drawback to using the compact H-bridge module is cooling it. The
higher density of components makes it more difficult to remove the heat.
Half-bridge does work fine for driving a TC, of course you only get half
the voltage out. Some people prefer having less parts and like half-bridge
for that reason. I think the advantage of higher drive voltage is the main
reason to go H-bridge, twice the power at the same current.
If you want to start small and relatively cheap, i really like the
FGH60N60SMD. Its a very fast part, i use it up to 400khz. I would suggest
keeping the peak current to just 200A, and if you need more you can
parallel them. Id also suggest a seperate heatsink for each transistor so
that you dont have to use electrical isolation between the transistor and
the heatsink (heatsinks would be live).
I like to use EEM.com and octopart.com to source IGBTs, i often find
distributors that i've never heard of that sell these parts in larger
quantities, but less $/part than digikey and mouser.
Steve
On Mon, Jul 7, 2014 at 9:01 AM, Jeremy Gassmann <jeremyee78@xxxxxxxxx>
wrote:
> Yeah, I definitely noticed the price tag. But comparing that to the
> CMM300 half bridge, it is on par with the price and it is all integrated
> into one package which I would think would help reduce parasicitcs. I guess
> this begs the question: what is the advantage of doing a half bridge versus
> a full bridge? I would assume that it would be higher power but I am still
> learning power electronics (I'm an RF engineer).
>
> I was also thinking that this part would kind of be one to grow
> into...basically I could start by running it way backed off (lower voltage
> and current) and reduce the chance of destroying it. That way I could learn
> with reduced risk of a costly mistake. Then once I am comfortable I can
> upgrade the power supply around it. Are these sound strategies to use or do
> IGBTs like to be driven more toward their limits? Thanks for the response
> and insight!
>
> Jeremy
>
> On Monday, July 7, 2014, Steve Ward <steve.ward@xxxxxxxxx> wrote:
>
> > Jeremy,
> >
> > The APTGLQ200H120G part looks outstanding, and the price tag matches
> that.
> >
> > Assuming you use a good driver that switches the IGBTs right near the
> zero
> > crossing in primary current, they should be capable of driving a fairly
> > large tesla coil. Id suggest operating within the 770A spec on the
> parts,
> > but at 600V thats quite powerful. Provided they have good cooling, one
> of
> > these parts could probably drive a 5-10kW coil.
> >
> > There really isnt an "Fmax" for a part, its a continuous curve of
> > "operating current vs frequency". Id suggest running at <100khz if you
> > really want to push the peak current level to the max, but they would
> still
> > work fine at less peak current and a higher frequency.
> >
> > Steve
> >
> >
> > On Sun, Jul 6, 2014 at 9:52 AM, Jeremy Gassmann <jeremyee78@xxxxxxxxx
> > <javascript:;>>
> > wrote:
> >
> > > Hello everyone. I am starting my journey on the DRSSTC road and have
> some
> > > questions regarding the heart of the system...the IGBT. There are a lot
> > of
> > > options out there including half bridge packages and even full bridge
> > > packages. Looking at the data sheets shows a lot of characteristics
> such
> > as
> > > input and output capacitance, rise and fall times, and switching
> energy.
> > My
> > > question is: what are the most important factors to look at when
> > selecting
> > > a device? Obviously current and voltage ratings are very important but
> > what
> > > about keeping capacitance as low as possible, etc? Are there any good
> > > documents out there the correlate these parameters to an fmax of the
> > > device?
> > >
> > > I did find a device that looks like it would be a good candidate: the
> > > Microsemi APTGLQ200H120G. It is a full bridge power module. Anyone work
> > > with this device or know if there any reasons not to use it? Thank you
> > all
> > > very much for the help!
> > >
> > > Jeremy
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