I'm trying to build my first DRSSTC from parts left over from a SGTC.

I'm reusing the secondary sircuit as is, with a resonant frequency of roughly 180kHz. I have 16x KEMET R76TR34704030J 470nF 1.6kV capacitors on hand, which were originally wired in series for a SGTC. I'd like to reconfigure these for higher capacitance and lower primary inductance.

I've been using Mads' handy calculator to try to design my nascent DRSSTC's primary capacitor, and it seems to be very difficult to get the thermal rise under control.

I'm inferring the ESR from the listed dissipation factor tanδ ≈ 0.3% -> ESR= tanδ*X_C = 1.6mΩ @180kHz.

I can't find any values for the thermal dissipation factor though, so I assumed they were about the same as the other Kemet capacitor Mads listed (R76UR3150SE30K), which was 23 ºC/W.

I'm benchmarking everything assuming 400A peak primary current (I have a full bridge of 8x FGY75N60 IGBTs, i.e. each IGBT is run in parallel, for an in-principle 450A of peak current handling), and a crazy overestimate for on time and BPS (200uS, 200BPS)

• 2 series strings of 8 -> 117nF, L_pri = 7uH, 15C rise per cap, 44A ripple current (!)
• 4 series strings of 4 -> 470nF, L_pri = 1.6 uH, 3.68C rise per cap, 185A ripple current (!)
• 3 series strings of 5 -> 282nF, L_pri = 2.5 uH, 6.5C rise per cap, 114A ripple current

My primary bus capacitor bank (3x Kemet 400V 2000uF caps in parallel, in hindsight I should've gone for 450V) is fairly feeble, it can only handle around 40A of ripple current. It likely needs further reinforcement if I want it to survive.

This is my first DRSSTC, so I wanted to ask for a sanity check on these numbers. Basically,

• Can I get away with configuration (1) as is, or do I need more bus caps?
• Would I be better off modifying the MMC for a higher primary inductance?

In terms of getting the secondary 'good-looking,' it's well worthwhile to build a winding jig out of whatever you have available. Mine was made out of some of my old mecanno, equipped with with a janked-together 555 PWM driver for my crappy motor. I don't know how I would have done it without it (still took 3 nights' work for 1300 turns because the wire kept doubling back on itself)

https://drive.google.com/open?id=1l5J9wIa7gPZUM2VoQrz6x1FAlDG1QWEF

The important parts to it were:

• Clean the PVC pipe thoroughly, making sure to get rid of any stray fibers or dust particles. I didn't do this well enough, and my final coil has some small hairs jutting out that are very annoying and an arc-over risk. Do not wind next to a carpet like I did.
• Tape the start of the winding down securely
• Turn the winder on, keeping pressure on the wires to keep the windings tight together
• Do not let the wires cross over- undo a frew windings if you have to. Make sure to keep tension on the wire with your fingertips - if it goes loose and the wire expands off the coil form, there is no way to fix it other than unwinding and rewinding.
• If you have any kind of mechanical counter to keep track of how many windings, definitely use it. It's also possible to estimate based on how long the coil is.
• When done, tape the end wire down with a full ring of tape
• Keep the windings in place by applying some kind of lacquer. I bought some of this stuff https://au.rs-online.com/web/p/electronics-varnishes-lacquers/8232640/ and applied 3 coats of it as the thing turned on my winding jig. It's not really necessary to get specialist electronics lacquer, I just grabbed it for extra legit-ness.

I've recently had the good fortune to crack open a microwave with a solid state 50N322A IGBT half-bridge power supply. I would very much like to cannibalise its larger parts to make some kind of SSTC. Working off http://pdf.datasheetcatalog.com/datasheets/toshiba/GT50N322A.pdf, the switching speeds aren't great, an order of magnitude slower than the DRSSTC grade FGH60T65SHD, but I'm hoping they might be just good enough for a low-power ~100kHz coil (to be achieved using a lot of windings)

I was looking at loneocean's SSTC 1 for inspiration - though my proposed coil will have more than double the windings (and a wider diameter to push up the resonant frequency), the same driver topology should hopefully work.

Before sinking any more thought into this - is this even worth building out, or am I just wasting my time on a project destined for mediocrity?