DRSSTC design guide - progress report

[Mads Barnkob]

I got the MMC article updated (password is still: "test"): http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/mmc-tank-capacitor/

MMC calculator has also been updated with the correct dissipation and temperature rise calculations: http://kaizerpowerelectronics.dk/calculators/mmc-calculator/

Please check it out and see if you can find any errors or suggestions for improvement

Now I just need to add some more pictures to the MMC design article and it will go "live"

[Mads Barnkob]

It only took me a mere 4 years from I first started this article about the MMC until it is now done for public released

Not that it took me 4 full years to write on it, but it has been a on/off gathering of information and then finally making a write-up on it.

I hope this will help many builders understand MMC design better: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/mmc-tank-capacitor/

[Hydron]

Have had a quick look through it, is some nice work but I'm not sure I subscribe to the idea that the MMC layout has a big effect on current sharing.
I would have thought that any sharing issues would only arise if the reactance of each capacitor string is similar in magnitude to the parasitic resistance/inductance of the connections between the strings.
Given that the reactance of a 100nF capacitor is ~16 ohms at 100kHz this should completely swamp any effects of the connections (unless they are _really_ bad) and thus force nearly perfect current sharing.

I'd personally focus more on keeping enough distance between capacitors, at least when being run at high RMS currents, so that there is less chance of hot spots.

[flyglas]

Hi Mads,
your calculation of the temperature rise of the MMC seems to be correct, but your conclusion is wrong.
When you are calculating the temperature rise with the power dissipated within the capacitor (I^2*ESR) and the thermal resistance, than your are calculating the steady state and not only a limited period of time.

Cite: "While almost 10ºC does not sound like much, we have to remember that this is for a single second of operation."

In theory you only have to let the capacitor be able to cool down enough between pulses, when the temperature rise (at steady state) is over the allowed temperature rise of the capacitor.