Author Topic: Micro drsstc (Read 17820 times)

oneKone · « **on:** February 27, 2018, 03:19:48 AM »

After completing a version of mads drsstc ii I've now caught the drsstc bug! So time to get building a new one.

The secondary was originally wound for a sstc but the fres seems low enough for a small to-247 half bridge setup, in which i'll try some 60n60 igbts from aliexpress.

current actual/ calculated specs;

Secondary: 76 mm od, 129 mm long, 104 mm winding length, 0.13mm wire, about 800 turns
Topload: 160mm diameter, 40mm high spun aluminium toroid. Secondary and toroid give 370khz
Primary: aiming for 7 turns of 3.2mm copper tube tapped at 4.8 turns
Primary resonance capacitor: 47nf Cornell-Dubilier Polypropylene 3kv
Full bridge of to-247 60n60
Driver: a steve ward 1.3b variation from ebay
___________________________________________

One thing i might try is to wind a dual? 1:33:33 ct using 3 epcos n30 ferrite rings (https://au.rs-online.com/web/p/products/2120982/). something similar to loneoceans drsstc 3 ct arraignment. The last time i ordered one of these driver it took quite a long time to get here. so potentiality this project could appear to be abandoned, in reality it would be me waiting for parts to arrive.

core to the left*

CCX191 · « **Reply #1 on:** February 27, 2018, 05:17:19 AM »

Looks like I have returned at the right time! Looking forward for more!

Sadly I still I can't work on my coil till June $:-\$ College is indeed stressful.

oneKone · « **Reply #2 on:** March 07, 2018, 12:38:54 AM »

Cheers @CCX191

A small update, the ct cores and resonant capacitor have come. Just waiting on the driver itself and the igbts. I don't think I'll start building until everything arrives.

oneKone · « **Reply #3 on:** March 13, 2018, 02:52:00 PM »

Another small update!

i have pretty much all of the components minus the driver so i'm thinking i might get started on the construction. Originally i was going to try a halfbridge of 60n60 igbts but i might try a fullbridge. The way i'm thinking of constructing it is a point to point style. I've attached a picture of what i'm thinking about going with.

Mads Barnkob · « **Reply #4 on:** March 14, 2018, 10:33:10 AM »

Minimalist bird nest is good for low inductance, but it can be hell to take apart when a IGBT blows up. So try to think replacement into your layout.

Two individual heat sinks will properly also make it easier for you to have access with wires for DC bus and inverter output.

oneKone · « **Reply #5 on:** March 14, 2018, 02:18:45 PM »

cheers for the advice about the inverter layout. Before checking to see if there were any replies i ended up making the inverter. I guess ill see how much of a pain it will become in the future! I also received the ebay driver board. looking over it and by the markings it appears to be a ud3 variant.... i have absolutely no knowledge of the new drivers, hell i have no knowledge of the 2.7c!

Hydron · « **Reply #6 on:** March 14, 2018, 05:08:03 PM »

It's not a UD3 (that's a completely different design based on a PSoC 5LP - see the "Next Gen DRSSTC" thread), but the driver is definitely of interest - if it works well it could be a useful option for a pre-built, cheap driver. Please let us know how it works - I'm not sure anyone has tried this one before!

oneKone · « **Reply #7 on:** March 15, 2018, 12:38:08 AM »

Thanks for clearing that up Hydron, I'm way out of my depth past the 1.3b driver. After a bit of digging I've found this thread on 4hv.

http://4hv.org/e107_plugins/forum/forum_viewtopic.php?179388

oneKone · « **Reply #8 on:** March 17, 2018, 12:54:10 PM »

small update....... the driver doesn't work! i looked over all the basics, feedback ct phasing, tried changing the gdt phasing, replaced the feedback ct with a function generator and finally ran the coil/ inverter with a sstc driver, which works awesome! i honestly think the driver is just doa. I think the biggest problem with buying drivers like this is there's very little to no information on other forums or documentation. I'm going to try a bit more digging and contact the ebay seller to see if he might have any more information on it.

futurist · « **Reply #9 on:** March 17, 2018, 02:51:53 PM »

Sorry to hear that. Does it produce any output on the GDT?

oneKone · « **Reply #10 on:** March 18, 2018, 02:00:59 AM »

Quote from: futurist on March 17, 2018, 02:51:53 PM

Sorry to hear that. Does it produce any output on the GDT?

i thought it did but after read your comment i checked again. The tc4423 was only outputting one side of its outputs, so after desoldering and soldering flyleads to a ucc27425 it now works! But..... it only starts oscillations at 250v input so i emailed the seller asking for a user manual. it seems the the 1:33:33 feedback ct is too large?

All that aside i did manage about 300mm streamers to free air! it wont play midi but i'm hoping after i can get some documentation i can get it working properly.

futurist · « **Reply #11 on:** March 18, 2018, 11:22:53 AM »

Quote from: oneKone on March 18, 2018, 02:00:59 AM

it seems the the 1:33:33 feedback ct is too large?

Probably yes, what is your primary current? Steve wrote somewhere that his driver works best with about 1 A of feedback current

oneKone · « **Reply #12 on:** March 18, 2018, 12:53:30 PM »

It's running about 200a primary current.

edit:
even with a 1:200 ct for the feedback the operation hasn't changed. i have also ran it without a feedback ct and it performs the same so it obviously has another part damaged on the board.

futurist · « **Reply #13 on:** March 18, 2018, 02:28:22 PM »

You can try with 1:15:15 CT which gives 1:225 ratio
I tested that CT for feedback in my 40N60 DRSSTC inverter and it works fine, even with 30 V on the bus

oneKone · « **Reply #14 on:** April 09, 2018, 05:58:29 AM »

I just received the new driver, so now the project can get back on track! I've been thinking for the frame I might use 15mm PVC pipe and fittings. I think this way could be perfect for a small coil, light and modular.

The driver is the ud1.3b through hole equivalent and it included a small transformer, although I bought an 18v SMPS for the driver.

oneKone · « **Reply #15 on:** April 09, 2018, 12:09:00 PM »

So I basically pushed over other small projects on my desk and quickly had the coil running. All I can say is that I'm excited to get this finished and tuned now! Rough calculations put the streamers to about 370mm. I have a 14 second video on coilsmiths (Facebook's page)

Nijin · « **Reply #16 on:** April 09, 2018, 10:05:50 PM »

Good job !

I plan to make a similar small drsstc. What is your coupling coefficient k ?

oneKone · « **Reply #17 on:** April 10, 2018, 02:10:30 AM »

Quote from: Nijin on April 09, 2018, 10:05:50 PM

Good job !

I plan to make a similar small drsstc. What is your coupling coefficient k ?

Cheers.

To be honest I've never calculated the coupling coefficient. i calculated it in javeTC (which I've never used either!) which calculated it to be 0.45, the recommended was 0.13.

oneKone · « **Reply #18 on:** April 10, 2018, 11:35:10 AM »

I've almost finished building the coil.... Packing everything into a small form factor is hard! One thing I've realised during testing is that I'll need active cooling, without it the heatsink gets pretty warm after about 15 seconds of playing a midi track.

In one run (assuming I scaled it correctly) I had almost 450mm streamers to free air! The tight coupling has been a bit of a pain but i think I can get it under control.

Mads Barnkob · « **Reply #19 on:** April 10, 2018, 10:01:27 PM »

That looks awesome oneKone!

That is one powerful little coil you got yourself built there and with 0.45 coupling don't you have problems with racing sparks or flashovers? If not, you must have hit a good tuning point where you transfer all your energy

Do you have youtube to you can just put video link in post to embed the video?

High Voltage Forum · « **Reply #19 on:** April 10, 2018, 10:01:27 PM »

Author Topic: Micro drsstc (Read 17820 times)

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