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10KVA DRSSTC (Complete)

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Goodchild

Sun Jan 02 2011, 06:44AM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

UPDATE:
Well after some more work, the bridge and base are now mostly complete. The bus structure is 1/8" thick aluminum at the moment may swap it out for copper in the future. Also large casters added to base for easy movement. When complete I expect the coil to weigh a couple hundred lb, so those large caster will come in very handy.

I can get the toroid on without a ladder "thank god" but just barely. The next think to build is the MMC and all that is left after the MMC is final assembly and testing can't wait!

with the new casters the top of the secondary is about the same height as my head "about 6 feet" with the toroid on the coil will stand about 7.5 feet tall.

5308168311 6598484a6f

Steve Conner

Sun Jan 02 2011, 11:47AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

You seem to have a snubber cap across each IGBT. Are you sure you want to do that? In DRSSTCs, they're usually only placed across the DC bus.

Gregory

Sun Jan 02 2011, 05:12PM

Registered Member #2922 Joined: Sun Jun 13 2010, 12:08AM
Location:
Posts: 226

with a phase lead modern drive, the snubber capacitor in each igbt will be used???

Goodchild

Sun Jan 02 2011, 05:42PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

The snubber caps are still technically across the DC bus but at 1/2 there value. Is there something wrong with having them across each IGBT?

Even though I am using phase lead I like to have snubbers just as insurance.

Gregory

Sun Jan 02 2011, 07:38PM

Registered Member #2922 Joined: Sun Jun 13 2010, 12:08AM
Location:
Posts: 226

wrong no, but i think that the result isnt the best.. are you using steve ward ud2 driver? where can i get the schematic??

Goodchild

Sun Jan 02 2011, 08:38PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Oh wait I see why having the snubber there can be bad, correct me if I'm wrong but this how I see it. some of the AC from the tank could find it's way back to the bus threw the snubber caps?

Just I thought. come to think of it ive never hooked a snubber up this way in a DR and ive built a lot of DRs.

Wolfram

Sun Jan 02 2011, 09:07PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Gregory wrote ...

wrong no, but i think that the result isnt the best.. are you using steve ward ud2 driver? where can i get the schematic??

Yes, this is completely wrong, and will most likely explode the second you turn it on. Think of what happens when the lower IGBT in one leg of the bridge turns off and the upper one turns on.

Goodchild

Sun Jan 02 2011, 10:26PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

I see what you are saying thanks for pointing that out! will have to do a bit of updating on the bridge.

Goodchild

Mon Mar 21 2011, 05:37PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Ok I have not updated in a long time, but we had a very large jump in progress! Thus far I have completed the bridge, MMC, toroid, secondary, controller, and primary. All that is left to do is to mount it all to the base of the DR, for first light it was just sitting under the coil.

Steve Caton and my self standing next to my coil (I'm on right Steve on left) ready for first light!
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for reference I'm 5' 11" and my head just touches the bottom of the toroid. The coil is 7 feet tall.

The overall first light set up on drive way with 30A 240VAC variac and doubler on the right.
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The MMCs for both Steve and my coils. One MMC is missing fans that will go on soon. We did our MMC Dr. Spark style

It makes sparks wooot!
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For reference that step stool is about 3 feet tall.

Good quality large spark photo:

Are expectation for first light were exceeded greatly! We expected this sort of performance from the coil after we had a tweaked system, but first light provided some nice juicy 10+ foot arcs in 20mph wind. We were also amazed at how efficient this system is, we had the OCD in the system set to 800Apk and we only occasionally tripped it when did burst mode. You heard me right <800Apk for 10+ feet. We thought this was an error at first but we confirmed that it was running less than 800Apk the whole time.

We powered the coil from the 240VAC line using a 30A variac and a voltage doubler, so that we would get 680VDC on the bridge. The coil really seemed to favor break rates between 100 bps to 200 bps. We also ran the PW at about 250uS - 300uS on average. With more tuning and tweaking we expect to see 12, 13 maybe even 14 feet out of this coil. We will have to put the coil up on a stand for longer arc, because as of now it loves to hit the ground

Here is a video of the coil running 10+ feet

More photo's of the build and running of the big coil:

We also plan to test run Steve Caton's coil in the coming summer which is basically a twin of this coil. It will be really awesome to see these two coil doing MIDI.

Finn Hammer

Tue Mar 22 2011, 06:54AM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

Extraordinary performance! Congratulations!

Long on-times you are running. Looks like it is a good idea to keep inductance high/current low. Another contender..

Cheers, Finn Hammer

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