Doing my First DRSSTC, i made a FeedBack + OCD and GTD transformers, is it good?

[AiYumeNekoAliena]

Hi,
since im trying to build a DRSSTC starting from 0 and im informing my self a bit.
I just tryed to make a FeedBack and OCD transformers as well as a GDT that i made following the amazing tutorial of the user "davekni" (big thx to that sweety person for helping novices out!)

Pls tell me if i did any mistake or is everything oky doky..
(I'm planning to use the same gdt for two different coils so i kinda eye eyeballed it... to be suitable for both... but currently imma use it with a coil that would be around 200kHz with topload)

• Im gonna use a full bridge of FGH40N60SMD
• I also remade the MMC that i talked about in a previous post thx to the help of the user "AstRii" (long story short, i found some old WIMA caps and asked if it was henaf but it wasent) with around 9kVdc and 58nF and i tryed to space out them out a bit and eavenly as user and administrator "Mads Barnkob" writed in the guides on the site "Kaizer Power Electronics" more specificly on the "DRSSTC Design Guide Updated With MMC Design Guide" section of the site. I did this for better cooling / insulation and better current pats were made by makeing use of huge solder+copper rails just to be safe and they are MKP of i guess high quality (correct me if im wrong there.. but i heard that yellow Arcotronics 4c4 caps are super good and it happend that i had them laying around).
• I also added a fan to the cooling system just as user and administrator "Mads Barnkob" suggested in one of my old posts.
• Im gonna use a wierd aliexpress ud1.3 driver that has no ocd potentiometer but a fixed resistor so i had to make a right count of turns for my FeedBack and OCD transformer...

Since im aiming for around 350Amps (pls tell me if is too much of an expectation for my IGBT's) and the wierd board works like this:

2000:1 = 400A
1000:1 = 200A
500:1 = 100A
250:1 = 50A
1:1=0.2A

i just decided to go as close as i could to 1750 without going over it (that would be 1000[200A]+500[100A]+250[50A]=1750[350A])... so with a 41 winding on one core and 42 winding on another core.. that give us around 1722 turns when connected thogether with a single winding... so that would be around 344.4Amps.. pretty close to what i intended it to be...

Pic of the OCD/FeedBack CT's and GDT:


Pics of the MMC:



Pic of the cooling fan added to the radiator for better IGBT cooling:


Pics of the first possible components layout, very very small footprint, just 25cmx25cmx15cm[WxLxH] (please tell me if there is anything too close or wrongly placed for it to work properly):




P.S.: Thx a lot for your help you all!

[davekni]

i just decided to go as close as i could to 1750 without going over it

1722 is plenty close.  I wouldn't change.  But you could get 1750 with 35T and 50T.

CTs and GDT look fine presuming core material is appropriate.  No way to tell core material from pictures.

Remember to add a bleed resistor across H-bridge output as Mads recommends on his site.  Otherwise startup issues are more likely.

Good luck with your project.

[AiYumeNekoAliena]

CTs and GDT look fine presuming core material is appropriate.  No way to tell core material from pictures.

Sorry, i forgot to mention it, i will add it leater, its an N30 (ferrite) core, its around 40mm est. diam. x 23 int. diam. x 16.2/16.5mm H.

sould be oky i guess, pls let me know!

Remember to add a bleed resistor across H-bridge output as Mads recommends on his site.  Otherwise startup issues are more likely.
Good luck with your project.

I didnt look into the bridge yet, it was an old bridge i did years ago and never used so imma check it agin to see if its all goody... i posted the schematic some days ago... it was a bit complicated to understand as someone told me already... im not an expert at all in drawing schematics... pls let me know if you can take a look at it and tell me if it looks good, i already know i have to remove some 1.5KE400CA diodes and i already changed the mmc as stated before.

Also pls could you kindly tell me if whe arrangement is good? cus i would start to design the box around it with my 3d printer if it is...
please let me know if there is anything that i sould do to prevent problems with my arrangement... i already know that i need to put the driver into some shielding like faraday cage but idk the rest... if you notice anything wrong im there to improve it! super thx for now!

Also super thx for the good luck! I really need it haha!

[davekni]

FGH40N60SMD

Have you found other posts where this part is being used to 350A?  Most parts can't be pushed that far beyond specified current (120A rated pulse current for FGH40N60SMD), though perhaps a few can be.  I'd limit to 180A unless other posts show this specific part can be pushed farther, especially when using UD1.3 that doesn't have phase-lead.

I didnt look into the bridge yet, it was an old bridge i did years ago

H-bridge construction is important, not just schematic.  My tutorial for H-Bridge construction (starting with half-bridge and extended in later posts):
    https://highvoltageforum.net/index.php?topic=1324.msg9795#msg9795

[AiYumeNekoAliena]

FGH40N60SMD

Have you found other posts where this part is being used to 350A?  Most parts can't be pushed that far beyond specified current (120A rated pulse current for FGH40N60SMD), though perhaps a few can be.

Sorry, i thought they where same as HGTG30N60A4D that has 240 max Amps in pulsed.. and saw someone useing them at 350+..

back to the OCD/FeedBack CT.. i will keep it under 120/130.. i want it to last.. if tou tell me it can handle 180 without breakeing then i will use it around 180.. let me know pls!
thx for makeing me check even if i was gonna do it by my self leater today when i will take a look at my old bridge and connections!

[davekni]

i will keep it under 120/130.. i want it to last.. if tou tell me it can handle 180 without breakeing then i will use it around 180.. let me know pls!

With phase-lead (UD2.7) these parts would likely handle 180A peak.  Without phase lead (UD1.3), 120-130A is likely fine, perhaps to 150A.  Depends on duty cycle and maximum on-time and heat sinking (especially mounting and insulator and heat spreader if used).  This is just my estimates based on current ratios of other TO247 packaged parts.

[thedoc298]

Nice build, what is the voltage of the yellow caps, can't see the value.