First DRSSTC: PCB Critique needed!

[matt0852]

Hi everyone!

I'm intending to work on a DRSSTC soon! It's my second coil, my first was a SSTC based on Loneocean's SSTC 2 and Steve Ward's mini SSTC.

Here are the calculated specs for my planned DRSSTC:
Secondary: 6cm dia, 18cm length, 1400 turns, AWG36, 296.45kHz
Primary: 12cm dia, 3cm length, 6 turns, AWG14, 245.15kHz (17% detuned)
Topload: 4.5cm minor dia, 18cm major dia
Tank cap: 0.068uF 3kV CDE
IGBTs: FGA60N65SMD, halfbridge
Coupling: 0.187

For the halfbridge, I am trying to design a low-inductance, high current PCB layout to be fabricated. Here are the top and bottom of the PCB. I would greatly appreciate any feedback regarding my PCB design. It's my first design, so feel free to criticise it!

FYI, I am from Singapore, line voltage is 220VAC.

Thanks!

[Mads Barnkob]

Hi and welcome to the forum

I like a little higher diameter:length ratio on the secondary coil, but this will work fine.

The high voltage rating of your MMC will be present between the capacitor and primary coil connection, so the creeping distance on the traces from MMC capacitor to connection point should be much wider, and just to be sure, also make them wider for the IGBT to MMC capacitor trace.

You could also extend the PCB to include the gate resistors and back to back zeners.

[matt0852]

Thanks for the suggestions!

Do I need to ensure the 10uF and 1uF caps are physically right next to the IGBTs to better smoothen out any voltage spikes? The PCB layout would be neater if I put the primary cap in between the IGBT and the 10uF cap instead.

[Mads Barnkob]

Actually, just move the resonant capacitor off the board, there is no reason to have it there when it is just a single capacitor that can be put in series with the leads to the primary coil.

You can also see how I placed capacitors on both sides of the board to save space.

I did that on my http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-ii/

[matt0852]

Brilliant idea! Thanks!

[matt0852]

I've changed the layout. Is this better?

[Mads Barnkob]

I would have a larger clearance between the power traces, but that is just to be on the safe side, there is room/surface/copper enough to do it. But someone else with more experience in tight PCB design like this should properly comment on it.