Post by: Mugi30 on May 03, 2020, 09:40:34 PM
I signed up and so I make my first post hoping to be welcome ::)
i have for project since....5Years (yeah) to make a medium/large Dual resonant coil..
I already have some of the parts following the pictures.(Primary, MMC, bridge, i will give specs of them
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the bridge is made with SKM300GB123D, i try to make 40-50khz Resonant frequency, theses IGBT are not verry fast
[ Invalid Attachment ] 2 MMC made by me
the grey mmc are arcotronics R76 1.2uf 630VDC, 12 serie of 5 parallel, 7560vDC and 500nF in total (each caps have 450 dv/dt, 540A pk,7.5A RMS, 2700 Apk, and 37.5A RMS total)
the white MMC use multicomp pro caps, 1200v 1uF each, 9 serie of 4 in parallel, 10800Vdc, 444nF in total, (each caps have 1000Apk, 25A RMS, 1000 Dv/dt, for 4kA Pk, and 100A RMS)
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the oscilloscope with damped sine wave is a test when i connect a CT with a primary circuit on a DC bus voltage, just for see if the core is okey.
The scope with square wave is a test with GDT
all cores used are TDK N30 cores, so permeability are 4300, is it ok?
I will update as I go along
advice and help are welcome :)
Thanks!
Post by: davekni on May 04, 2020, 06:38:04 AM
Post by: Mugi30 on May 04, 2020, 06:04:10 PM
I hope so too :).
besides yesterday I did a bizzare test by testing my CT connected to the primary LC circuit, I noticed something weird but I think it's due to the inductance generated by the CT, I have a frequency of 40khz when the output of the CT is not short-circuited by a resistance (resistance load for example) but as soon as I add a resistance at the output, already I have a more stable start of oscillation, but the frequency that give my CT up to 50khz ??
an idea? would it be the CT which adds an inductance which causes it to lower my frequency of the LC circuit by 10khz? and in fact I have a frequency of 50khz at the base?
Post by: johnf on May 04, 2020, 09:28:02 PM
Post by: Mugi30 on May 04, 2020, 10:43:46 PM
suddenly my real resonant frequency will be rather 50khz suddenly because I shunt the CT :)
Post by: Mads Barnkob on May 06, 2020, 09:37:41 PM
It is all looking real good and your white snubber capacitor MMC is just perfect for a SKM300 brick coil.
Seems you just need to settle on a secondary + topload, wire it all up and you are ready to make sparks! (do not feel back about the 5 years, I spend 4 years on my large DRSSTC :) )
Post by: Mugi30 on May 08, 2020, 08:10:20 PM
after soldered all, i made first test with function generator and oscilloscope
at the first test, the driver worked but at CW, I didn't know where it came from. after a small reflexion,
I thought of a pulling resistance to the ground which was missing, and it was the case looool!
in the pictures, my oscilloscope show directly the signal with a IGBT connected to the GDT, (here is a SKM bricks) with a gate resistor and just a 30v diode TVS.
i just have a priblem, i have a damped sine wave after each cycles, with 800mv peak... is it dangerous? i dont have it if i test the GDT imput of the driver..
so i have it with the GDT output too.. is a really problem?
the feedback works well if the peak voltage of of the CT simulated to my function generator is 3v minimum, ! if the voltage down, i ear a BRRRRBRBRB due to the instable signal.
pictures (damped sinewave is the picture when i measure it with curcors)
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+also, the IC who driving the feedback is not a LT1016, TL3116 or MAX913, this is a AN8561ANZ, it works verry well! :)
Post by: davekni on May 09, 2020, 04:21:34 AM
The gate signal ring-down looks like the gate-drive has an emitter-follower output stage, or something other situation where the gate voltage isn't hard-clamped to 0V between bursts.
Post by: Mugi30 on May 09, 2020, 12:34:24 PM
what's the minimum vshoult it read to the feedback circuit for starting ? I've seen the circuit clamp the voltage to ~ 1.6v approx with resistors and diodes..
thanks! ::)
edit: the 3v was required because the burden 51 ohm of CT circuit resistor was connected !! i have the signal at 1v too now! and probably with more low voltage! :)
i just need to resolve this problem of damped sinewafe after each cycles... this is my single and last small problem, someone say me that's not a big problem for IGBT...
Post by: Hydron on May 10, 2020, 02:05:51 AM
Just a note about the CT - the general rule is to never use a CT without a burden resistor - it is quite capable of also acting as a voltage transformer (up until it saturates anyway) so you can end up with significant voltages on the output!
Post by: Mugi30 on May 10, 2020, 02:38:46 AM
the damped sine wave is at the outpout of the GDT. i dont checked the output of the fullbridge of SKM300GB.
Post by: davekni on May 10, 2020, 04:15:03 AM
Post by: Mugi30 on May 10, 2020, 10:01:09 AM
That's from ProfDC9
ud27-schematic.pdfthe difference i dont think that's from that, but, mine for C34 is not a 1uF, but a 4.7uf film cap. with its 15ohm serie resistor (R24)
At the stage of power supply with LM7824, here is at output a 4.7uf with a serie resistor, i dont put them on the pcb too (R1, C4)
Post by: Hydron on May 10, 2020, 07:01:14 PM
hey Hydron!I think this will be parasitics again, probably the leakage inductance of the GDT (which is shorted on it's primary by the driver FETs) resonating with the IGBT gates, with damping provided by the gate resistor. Should still not be an issue given the low amplitude (not even close to turning on an IGBT).
the damped sine wave is at the outpout of the GDT. i dont checked the output of the fullbridge of SKM300GB.
Post by: davekni on May 10, 2020, 10:34:42 PM
Post by: Mugi30 on May 10, 2020, 10:44:03 PM
i think he mean UCC27423 and not 27243 yeah,
Post by: davekni on May 11, 2020, 12:16:53 AM
TC4423 should work fine.
I was thinking incorrectly. C33 and C34 are still in the GDT path even with both driver outputs low, so that ring would be normal, nothing to worry about.
Post by: Mugi30 on May 11, 2020, 08:04:30 PM
I ended up finding only 160mm in diameter. 200MM and more is difficult to find.
is it serious to have a secondary length 6 times its diameter?
it is said that a dimension of secondary coil must need in maximum length 5 times the diameter ...
I saw Tesla coils break this rule and still work well
Mugi
Post by: davekni on May 12, 2020, 04:57:39 AM
Post by: Mads Barnkob on May 12, 2020, 08:59:26 AM
Nice! :D i just need to connect each component together for my dual resonant coil, i just need to finish my secondary coil. Basicely, i wanted to make my secondary coil with a 200mm diameter.
I ended up finding only 160mm in diameter. 200MM and more is difficult to find.
is it serious to have a secondary length 6 times its diameter?
it is said that a dimension of secondary coil must need in maximum length 5 times the diameter ...
I saw Tesla coils break this rule and still work well
Mugi
Nothing is set in stone!
My recommandations in the DRSSTC design guide ( http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/secondary-coil/ ) follow the best practise, known to work designs and is a guide to build something that is based on experience from many different builders. It is not an absolute list of solutions and that is also why I write "The color coding of the secondary system impedance should be understood as a guide line towards the magic 50k which was explained further up. I made a spreadsheet with all these and more example calculations. The magic 50k is thought to be too high for large or very large coils that will experience serious spark loading, here it properly is more suitable with 40k or even as low as 30k. Experimentation is needed to confirm these assumptions."
what about wire size? what is your estimated impedance of the secondary coil? If it lands inbetween 30-70K I would not worry about changing anything :)
Post by: Mugi30 on May 13, 2020, 12:04:15 AM
I use 0.4mm diameter (AWG26?) for my secondary. now i have 90cm winding lenght for 160mm diameter...
Post by: oneKone on May 15, 2020, 05:38:45 AM
Nice looking build so far, I'm a fan of the solder lug style capacitors. I've used them in a few builds now and they're (the kemet ones I've used) basically bulletproof! Looking forward to see your build progress!
Post by: Mugi30 on May 17, 2020, 02:57:13 PM
Post by: Mugi30 on May 18, 2020, 10:05:14 PM
The secondary alone résonate at 107khz, and with the big topload, IT résonate at 58khz!
I used plumbing aluminum sheath
two or three more things and I can try it out first!
Post by: Mugi30 on May 18, 2020, 10:10:09 PM
À picture with the topload
Post by: ritaismyconscience on May 18, 2020, 11:54:27 PM
Post by: Mugi30 on May 19, 2020, 12:05:51 PM
I need to make connexions for the topload now and make this Week the first light
Post by: Mugi30 on May 21, 2020, 09:15:57 AM
So when I turn up the on time, It dont up, I think that's because the power source is around 50w loool
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Post by: Mugi30 on May 21, 2020, 11:55:37 PM
the video with very low power test!!!
at the last message i said my primary doesnt worked, that's false (i dont explained very well lol), we can see the primary courant signal at the scope.
i used so a transformer 40 VA of power, for 80v BUS. i think i'm verry limited with this supply because when i turn more the on time, the primary current sown quickly. but after , because the power supply dont give too much for the bridge and primary circuit.
Post by: ritaismyconscience on May 22, 2020, 01:15:36 AM
Post by: Mugi30 on May 28, 2020, 10:07:59 PM
And for phase lead settings? Here is photo aboutissent voltage output bridge and the primary current with output of CT, as you can see, I have a lot of pics and a lot at the current signal, wtf? Are real? [ Invalid Attachment ] [ Invalid Attachment ]
A update of the omegaDR now. I have wirh 40w 10cm sparks and wirh pulsé skip 30-40cm sparks..
I'm waiting also for a 2kva variations for it. Will Be 1.2m for 2kva power?
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Post by: Mads Barnkob on May 28, 2020, 11:29:00 PM
The spikes on the blue current signal is switching noise and you might need to address that on the CT used to measure the current.
The spikes on the yellow is pretty good for low voltage testing, no need to worry there.
At 2kVA you will hit around 1.5 meter.
Post by: Mugi30 on May 28, 2020, 11:40:37 PM
I changer the résister burden ce nnected to the CT (5 to 600ohm) for better check at zéro crossing. I have always thèses, but I have down pk output voltage bridge! [ Invalid Attachment ]
I moyen almost peak voltage, but the peak output CT are really always Here... (We dont see Ir because thèses pk are to 800mv Max) is that dangerous to have this blue pics at output CT?
Post by: davekni on May 29, 2020, 12:00:26 AM
Post by: Mugi30 on May 31, 2020, 04:15:17 PM
For simple, I made quick voltage doubler for 160v from 80v.
So, the problem was my transformer that give this voltage but with not with a high power (40w) this Is why I used just one shot, interrupteur, with normal mode the dc bus Caps voltage down quickly.. Here is the picture: [ Invalid Attachment ]
I have ans vidéo about this..
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For this Week I wait a Nice variations for some test !
See ya
Post by: Mugi30 on June 03, 2020, 12:27:06 PM
À vidéo à bout the OmegaDR.
I used 1.5kva power formation this test.
I dont checked the OCDE set, this Is why I testée quickly
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Light was not heating, I use SKM300GB123D :D
Post by: Mugi30 on March 19, 2021, 07:38:05 PM
lets share pictures ;) (no doubler used in pictures! and not at ful power) [ Invalid Attachment ]