Re: [TCML] Re:Pros and cons

["Dex Dexter" <dexterlabs@xxxxxxxxxxx>]

Fez,
20 microfards and 4.4 kV will give bang size of aprox 193 J!
At F ~ 25 kHz you will have primary characteristic impedance
only 0.3 ohms and really high peak primary current ( 13 kA +).
I doubt anybody has ever worked with  tesla coil primary currents
of this magnitude.One thing is certain,your coil will not be a very
efficient one.I doubt it would be able to reach efficiency like 80%.
Pay your attention to this fact.
I hope IGBT HV module you refered to will be useful for the coil.
BTW,interesting standpoint about efficiency issue I must admit.
Reminds me of the view of coiler Peter Teren (aka Tesla downunder),
except in one big difference.He wants and likes sparks,you don't.

Dex 

 
  




On Sun, Nov 29, 2009 at 12:17 PM, <uhvsystems@xxxxxxxx> wrote:

>
> Well,it appears that for our purposes 3rd variant is the most adequate
> then.Having less complexity than DRSSTC but still offering enough of the
> control.Moreover,I checked files of the power electronics department to
> reveal some CM 600HB-90H modules are kept in stock.Rated 4500V,900A they are
> big IGBT bricks (maybe even too big).I'm not that much into power
> electronics to be sure if the module is suitable for tesla coil service I
> have on mind.Will investigate in their catalogue to find out more
> details.Generally such devices are quite robust,hot-spot and current
> crowding problems are nonexistent,and the need for external snubber circuits
> is minimal.If we manage to make it work in tesla coil service that would be
> great.With primary tank capacity 20 uF charged up to 4400V, and with tesla
> coil efficiency say about 80%, 155 joules could be supplied to tesla coil
> secondary circuit.The estimate  is sufficient to cover upper testing limits
> we are prepared to go to.
> I must say few words about the efficiency and where is its importance for
> us.
> The importance is mainly in the point that efficiency determines primary
> energy needed to charge secondary circuit to predetermined voltage.From the
> point of technical operation and reliability it is also important since
> nobody wants to overheat or blow up things due to increased dissipation.
> From the point of chasing some high efficiency figures for the sake of
> economical power utilization,well...that is totally irrelevant to us.
>
> Regards,
>
> Fez Zaev
>


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