High Voltage Forum

Tesla coils => Dual Resonant Solid State Tesla coils => Topic started by: DaiKen on May 25, 2018, 08:11:51 AM

Title: Big filter caps obtainability
Post by: DaiKen on May 25, 2018, 08:11:51 AM
Hi group,

After a few months of preparation (studying theory and obtaining the necessary equipment) my first attempt to build a DRSST based on Mads DRSTC I  (http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-i/) can start. I would like to begin with the power supply and need some advice where to obtain the more pricey parts:
These specific parts seem to be running of out stock, are relative expensive and seem hard to get in my country, The Netherlands.

Can someone please advice me where to buy these parts (or suitable replacements) for a decent price?

Thanks in advance.

Kind regards,

Ton

Title: Re: Big filter caps obtainability
Post by: Mads Barnkob on May 25, 2018, 08:23:12 PM
When I built my coil, it was inspired by Steve Wards DRSSTC that used 40N60 mini brick IGBTs, which was running out of stock back then, so I had to invest in brand new 60N60 from digikey, that was quite the price to get 30 at once, but I sold 16 of them to other coilers and used the rest myself.

For DC bus filter caps, your best bet is still ebay. You even have one of the better electronics reseller located in the Netherlands :) Tauritronics is worth checking out. https://www.ebay.co.uk/sch/Capacitors/4662/m.html?_nkw=&_armrs=1&_ipg=&_from=&_ssn=tauritronics

Happy hunting for the parts!
Title: Re: Big filter caps obtainability
Post by: TDAF on May 25, 2018, 08:35:25 PM
I don't think you should be bothering yourself with the 60n60c2d1

I find that there cost doesc' justify their benefits

You'll be better off using something like a FGH60n60SMD or a FGA60n65SMD which are available at a fracction of the cost

and with a good enough heatsink have identical performance
Title: Re: Big filter caps obtainability
Post by: Teravolt on May 25, 2018, 08:47:09 PM
I found thease in ebay if you don't mind the weight. I assume they are genuine

 https://www.ebay.com/itm/10-PCS-IXGH60N60C2-TO-247-IXGH60N60-HiPerFASTTM-IGBT-C2-Class-High-Speed-IGBTs/302241860326?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

and if you can order from digkey I am trying thease

https://www.digikey.com/product-detail/en/ixys/IXYH100N65C3/IXYH100N65C3-ND/4496595

they are powerful and affordable. if you can get the  IXGH60N60C2 you can double up on them
Title: Re: Big filter caps obtainability
Post by: oneKone on May 26, 2018, 06:09:23 AM
I've tired a few of the cheaper mini bloc ixgn60n60 from ebay and have been burnt, although at the time i think i had my ocd set too high. i ended up finding a seller in the u.s. i bought each module for $60aud and paid $35 aud for shipping.

the way i try to buy is off markings and if the price is about the same as a genuine product, although its china so who knows.

https://www.ebay.com.au/itm/IXGN60N60C2D1-Manu-IXYS-Encapsulation-MODULE-Ultra-Low-VCE-sat-IGBT/121929162420?epid=1861908022&hash=item1c638b5eb4:g:hSIAAMXQpPhTkn6S
Title: Re: Big filter caps obtainability
Post by: Hydron on May 26, 2018, 10:40:17 AM
I would also suggest using a set of the Fairchild/ONsemi IGBTs, they have similar thermal impedance, are well tested and are very good value even from official distributors. Your options are fgh60n60smd, fga60n65smd (60A 600/650v, would probably go for the fga given similar price) or the larger
75A fgy75n60smd, which is probably worse value unless you're getting it from AliExpress or something (see my other thread about these).

I have hard switched the 75A parts up to 225A (their rating), and I'm sure others have soft switched a fair bit more than this. If you need to you can always put a couple in parallel (with separate gate resistors) - will still be cheaper than the alternatives!
Title: Re: Big filter caps obtainability
Post by: profdc9 on May 26, 2018, 01:36:05 PM
You may want to consider the FGH60T65SHD which is a newer part.  It has been recommended by OneTesla (http://onetesla.com/tutorials/drsstc-bridge-design) and is cheaper and more available.   FGH60N60SMD has been out of stock a lot of places I have looked.

Perhaps consider using 2 TO-247 IGBTs in parallel on each side of the bridge, even though it will double the cost, you will divide the current and heat over the two, running both more in their safe operating limits.  There is a PCB for a full or half bridge that can combine them together in the DRSSTC pcb pack I made, so you can assemble this more easily.

Dan
Title: Re: Big filter caps obtainability
Post by: Hydron on May 26, 2018, 11:37:41 PM
You may want to consider the FGH60T65SHD which is a newer part.  It has been recommended by OneTesla (http://onetesla.com/tutorials/drsstc-bridge-design) and is cheaper and more available.   FGH60N60SMD has been out of stock a lot of places I have looked.
These newer parts have some advantages, but it also looks like they use significantly smaller dies, and so have much higher thermal resistance. Probably depends on the use as to whether this is an issue or not.
Title: Re: Big filter caps obtainability
Post by: profdc9 on May 27, 2018, 05:18:44 PM
I was looking at the FGY75N60SMD vs FGH60T65SHD and the issue I saw was that it looked like the FGY part can handle more power and current, but the FGH part switches faster.  They have the same VCE.   For hard switching the FGY part is probably better, but I was looking at trying higher frequency switching, so the switching losses might become more of an issue, and the FGH has lower switching losses as well.  Anyways I got a bunch of the FGH parts and I am going to try them.  Unfortunately its very hard to get the FGH60N60SMD, it seems like it won't be available at least until mid-July.

Dan
Title: Re: Big filter caps obtainability
Post by: DaiKen on June 01, 2018, 12:27:20 PM
Many thanks to all who replied and helped out with advice!

I've found a rather good electronic parts reseller in The Netherlands, only problem is the big filter caps are even more expensive. The lowest price a came across during my hunt is around $45 per piece, no minimum purchase required. Anyone cheaper/better?

Your advice on the IGBT's is really very useful! The newer ones indeed cost a fraction of the 60N60's and I have enough information to go back to the design of the bridge  and decide between amps and switching speed (considerering the planned use of a midi-interrupter).

One small related question to Mads, what is the thickness of the copper sheet you use for the busbar in your drsstc-i bridge? (https://highvoltageforum.net/proxy.php?request=http%3A%2F%2F%5Battachment%3D1%5D%5B%2Fattachment%5D&hash=7d3863697bff2aa03c77da79c8bd8fde)

Warm regards,

Ton
Title: Re: Big filter caps obtainability
Post by: Mads Barnkob on June 01, 2018, 03:13:51 PM
It is just 1.2 mm regular copper plate.

I bought it in the sizes I needed on ebay, there is some fairly good priced sellers in the UK. Good part is that you can buy the sizes you need instead of buying a large plate and have a lot of copper scrap.

Here is a example of such a seller: https://www.ebay.co.uk/itm/1-2-MM-thick-COPPER-SHEET-PLATE-guillotine-cut-many-sizes/273232999138?var=572528275635&hash=item3f9df4b2e2:m:m7Mv_I9WtCY0CEnJwXgxAwQ
Title: Re: Big filter caps obtainability
Post by: DaiKen on June 01, 2018, 05:46:31 PM
Thanks very much, Mads. Knowing where to buy the sizes one needs is a priceless information.

Warm regards,

Ton
Title: Re: Big filter caps obtainability
Post by: DaiKen on July 14, 2018, 01:30:26 PM
Dear Mads,

Your specs of http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-i/ mention a 53A Iripple@70KHz@50 degrees Celcius for the capacitors. The ones I can find don't meet Iripple value (e.g. 15.6A @ 100Hz, 85 C and 25,5A @10kHz, 85 C). What is the minimum value necessary?

Hope to hear from you.

Kind regards,

Ton
Title: Re: Big filter caps obtainability
Post by: Mads Barnkob on July 16, 2018, 07:47:25 PM
Hi Ton

There is really no minimum ripple current specification, it all comes down to how high a temperature rise you can accept on your capacitors :) If you are only going for short run times, you can over load them some, but you should just calculate it and then parallel enough capacitors to have a good enough rating for the use you are going to give them.

See here: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/dc-bus-capacitor/
Title: Re: Big filter caps obtainability
Post by: oneKone on July 17, 2018, 04:18:06 AM
If you're still looking for capacitors maybe these might be suitable?

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F332416524854
Title: Re: Big filter caps obtainability
Post by: DaiKen on July 18, 2018, 08:22:21 AM
Hi Mads,

Thanks for your reply, I'll certainly will do the calculations. But not really sure about myself (building a DRSSTC for the first time) I'd like to copy your DRSSTC-i as much as possible. What me surprised was the word 'each' in your description:
each: ESR 39mOhm@100Hz, Z 27mOhm@10kHz and 53A Iripple@70KHz@50 Degrees celcius. 53A each? Those seem hard to get...

Hi oneKone,

Thank you too, but these are rather far away from the desired Iripple.
Title: Re: Big filter caps obtainability
Post by: profdc9 on August 14, 2018, 09:38:54 PM
If you're having a problem getting a high ripple capacitor, you could buy smaller capacitors and place them in parallel.  Make sure the wire lengths to the capacitors are roughly equal to ensure the inductance doesn't tend to favor higher current flow in the capacitor with the shortest leads.

Dan


Title: Re: Big filter caps obtainability
Post by: Teravolt on August 14, 2018, 11:21:39 PM
if you can by from ebay I fount thease

https://www.ebay.com/itm/Lot-of-8-450V-1800uF-Electrolytic-Capacitors-High-Voltage-NEW-In-Box/281050108182

moast any big electrolytics will do. if you are able to handle them the denser they are usaly the lower ESR. by all means this is not exact or scientific but some of the caps I have a definite feal to them. the purpace of the caps are energy storage for your bridge for frequency conversion. the ESR will determin how much heat your caps will generate but may not be a isue for what you are doing. people use all kinds of electrolytics for DRSSTCS. paralelling them decreases ESR 
Title: Re: Big filter caps obtainability
Post by: DaiKen on August 15, 2018, 10:54:26 AM
Hi Teravolt,

Thanks! I too found suitable capacitors on e-bay. The price is reasonable indeed, but the shipping costs are unfortunately not (capacitor $39.00 shipping $53.50 USPS Priority Mail International). Not my cup of tea. I also looked into these Chinese ones, they are probably cheap(er) because their iRMS and iRipple are rather low, too low for my planned coil at least.
I finally got mine from Digi-Key, they cost around $55.00, but orders over $60.00 are sent without shipping cost!
Title: Re: Big filter caps obtainability
Post by: profdc9 on August 15, 2018, 02:12:08 PM
You should check out "Surplus Sales of Nebraska" (https://www.surplussales.com/).  I think they ship internationally.

Also hamfests often have capacitors like these surplused out of linear amplifier power supplies or other high voltage supplies.  Hamfests in general can be a source of fairly cheap parts.  I have read that in the Netherlands there is a yearly hamfest in Rosmalen (http://radiovlooienmarkt.nl/).  It may be fun to check out.

Dan

Title: Re: Big filter caps obtainability
Post by: Teravolt on August 15, 2018, 06:05:47 PM
are threr any indurial or other surplus in your country of origen