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SSTC/DRSSTC low inductance PCB example?

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hsieh

Sun Mar 25 2012, 01:33AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

After reading some threads I start to understand the importance of low inductance PCB design.Are there any good example I can reference when designing my SSTC/DRSSTC PCB?

Thanks

Dr. Brownout

Sun Mar 25 2012, 02:38AM

Registered Member #2405 Joined: Fri Oct 02 2009, 12:59AM
Location: Wisconsin
Posts: 140

Basically you want to keep the traces as wide as possible use plany of grounds I like to use copper pours and attach them to the ground net. Some times I will even add guard traces attached to the ground net and place them on either side of a trace to keep the intereference down. Keep the traces as short as possible and use wide ground traces or pours. Here is an example of a board that works well, I use Orcad PCB Editor alot of the folks here use Eagle.

Dr. Brownout

Sun Mar 25 2012, 03:08AM

Registered Member #2405 Joined: Fri Oct 02 2009, 12:59AM
Location: Wisconsin
Posts: 140

Oops I attched the wrong file here is the correct one this will give you and idea anyway.
]driver_board_top_copper.pdf[/file]

hsieh

Sun Mar 25 2012, 03:17AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

What I want to know is the half/full bridge part of the circuit.Most designs I found on the Internet use IGBT bricks but I use TO-247 MOSFET/IGBT.

Dr. Brownout

Sun Mar 25 2012, 03:38AM

Registered Member #2405 Joined: Fri Oct 02 2009, 12:59AM
Location: Wisconsin
Posts: 140

I just edited this whole post, Let me see if I can find a layout using the TO247 I believe I still have one here, I use TO247 style in one of my coils let me see if I can find the file for you this coild works really I can post pictures of you want to see how I put it all together.

Dr. Brownout

Sun Mar 25 2012, 03:59AM

Registered Member #2405 Joined: Fri Oct 02 2009, 12:59AM
Location: Wisconsin
Posts: 140

Here is the Half bridge board I am using in my 9 inch coil, I use two of these basically a mirror of one side. But you can see how wide I made the traces. I kept the traces pretty wide. Here is a picture of the coil I am using them in.
]half_bridge_final_rev_a.pdf[/file]

Maurizio Valvo

Sun Mar 25 2012, 08:28AM

Registered Member #3219 Joined: Mon Sept 20 2010, 09:06PM
Location: LeinÃ¬ (Turin), Italy
Posts: 23

I attach a drawing and a couple of pictures of my DRSSTC full bridge board using TO247 IGBTs. It is double layer: top and bottom layers have the same drawing and are connected in parallel through the components terminals. The board is mounted on a single big heatsink. I achieved 1.2m sparks (about 4 feet) with this design. I used PCB123 for this project, I can share it if you like, just mail me.

]bridge_final_ext_3_7.123_composite.pdf[/file]

Dr. Brownout

Sun Mar 25 2012, 01:57PM

Registered Member #2405 Joined: Fri Oct 02 2009, 12:59AM
Location: Wisconsin
Posts: 140

Looks very good, nice wide copper connections and a big ground, you should have no trouble with this at all you have you snubber caps in place looks very good.

I am doing a couple of coils right now that use a full bridge of CM300 bricks, if you want I can post some pictures of that one. Someone else mounted the CM300 bricks end to end to a heat sink and the heat sink is large, so the layout is not the way I would have done that section, I had to cut some copper to make the connections and using those bricks end to end like that there really is no way to mount a PCB on the bricks like I want to do.

So on the second coil I mounted the bricks a little different. They are side by side and that just seems to make the world a better place...:-)

I am using fiber optics with the CM300 coil the TO247 style I am not using fiber optic on that, the interrupter is connected through coax which seems to work pretty well.

But as far as your layout goes I think you will have no problem there, be sure to heat sink those TO247's really well and use a fan. In my TO247 unit I am using 120VAC input into a doubler seperate heat sinks on each of the TO247 components and I have a fan blowing on them.

--Brian

Dr. Brownout

Sun Mar 25 2012, 02:23PM

Registered Member #2405 Joined: Fri Oct 02 2009, 12:59AM
Location: Wisconsin
Posts: 140

I posted a picture of how the CM300 are placed on this heat sink I think side by side is MUCH better as all the wiring can be kept short much shorter than this layout. Even though all my signals look good with only a small of ringing on wave forms the ringing is not high enough amplitude to cause the IGBT to back into the active region and they switch fine. On the next one they will be mounted side by side.

(Edit: I do not have the feedback and over current transformers shown on this picture)

--Brian

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