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Registered Member #10052
Joined: Thu Feb 07 2013, 11:31PM
Location: Overland Park, Kansas
Posts: 78
I just ordered some SLOT TEN-5-09's and SLOT TEN-5-10's.
This should cover the range (15-60uh) specified. I'll just have to try and see which one works.
I promised pictures:
Just finished the driver board this weekend. Hoping I didn't make any mistakes. Will need to test soon.
Some sheilding for the driver.
Indicators.
I'm having the primary supports laser cut from delrin. The primary tubing (1/4" copper) snaps into place, so I spent some time with the guys at Built-To-Spec test cutting some pieces to check the fit.
Winding the secondary. 6.25" dia, 20" coil height, 32AWG green enamel magnet wire, 2,100 turns, and 3/4 of a mile of wire! It never gets less grueling.
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
All I can say is.. WOW!
Everything looks awesome! Go big or go home, right?
Is the secondary PVC form one of those 24" drain pipes? I think I used the same for mine. Perfect 6.25" x 24" coil form.. dont have to buy 10ft of PVC for a 20" coil
Registered Member #10052
Joined: Thu Feb 07 2013, 11:31PM
Location: Overland Park, Kansas
Posts: 78
I know its pretty big for the bricks I'm using :P.
As this is my first drsstc, I didn't want to fuss with switching these big bricks at over 100kHz, and didn't want to mess with wire smaller than 32AWG. I know it can be done, but for the sake of minimizing the trouble I run into, I think this will work.
I called all over town looking for a foot-by-foot price for the 6" PVC, but everybody wanted to sell it by the mile.
Finally found it at the local hardware store. They had to make up a unit price for me, but it worked out.
I cut the end-caps out of 1/2" cutting board (polyethylene I think), and secured with 6 nylon screws on each end. Its very soft plastic, and easy to cut and work with.
Registered Member #10052
Joined: Thu Feb 07 2013, 11:31PM
Location: Overland Park, Kansas
Posts: 78
Thanks.
I know we run with a safety margin, and that AC rating is substantially less than dc ratings, but why do I see so many tank caps with >8kvDC ratings, on coils with primary voltages under 500 volts? I realize that peak current handling capacity is essential, but have been confounded by the voltages.
EasternVoltageResearch - I just ordered one of your guys' 4.5x18" torroids. Can't wait.
Registered Member #10052
Joined: Thu Feb 07 2013, 11:31PM
Location: Overland Park, Kansas
Posts: 78
So parts are pouring in.
Here I have one question.
I have a 420 volt 3400uf RIFA capacitor on the way. These seem to be preferred for bus filtering and storage.
I have currently two 4700uf 450v Sprague electrolytics.
I am going to run a doubler from 140 volts out of the variac, to get up into the 380-400 volt range.
Should I run the doubler directly on the bus? (That is, should I put two electrolytics in series as the storage, filtering, and doubler, right on top of the IGBT's), OR Should I run the doubler at the control end with the variac, and send 400VDC to the RIFA capacitor on the bridge. This would save some real-estate on top of the IGBTs, and minimize stray inductance in the bus.
I would immediately lean towards the RIFA on the coil end, simply because this seems to be a popular setup.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
HighVoltageFeathers wrote ...
So parts are pouring in.
Here I have one question.
I have a 420 volt 3400uf RIFA capacitor on the way. These seem to be preferred for bus filtering and storage.
I have currently two 4700uf 450v Sprague electrolytics.
I am going to run a doubler from 140 volts out of the variac, to get up into the 380-400 volt range.
Should I run the doubler directly on the bus? (That is, should I put two electrolytics in series as the storage, filtering, and doubler, right on top of the IGBT's), OR Should I run the doubler at the control end with the variac, and send 400VDC to the RIFA capacitor on the bridge. This would save some real-estate on top of the IGBTs, and minimize stray inductance in the bus.
Yes. Run the two doubler capacitors as close as possible to the IGBTs. These are your energy storage capacitors and all the energy that gets pulsed into your DRSSTC primary comes from these capacitors (not the power line) during each pulse. So you want them right at the IGBTs connected with BUSBAR, PCB Board, or thick wires. You also want them close to minimize inductance as much as possible.
Recall that in an inductor (ie. stray inductance), current doesn't want to stop instantaneously. So when you open your switch (i.e. IGBT), the current does NOT want to stop flowing and to keep current flowing, any inductance (inductor) will try to increase the voltage to keep current flowing, and this is what causes the big transient voltage spikes at your IGBT switching edges. By reducing stray inductance in your layout, you can reduce this effect.
So keep the energy storage caps close, and the routing as clean and tight as possible.
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