Author Topic: My first DRSSTC  (Read 1027 times)

Offline erdal

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My first DRSSTC
« on: September 20, 2018, 10:52:53 PM »
Hello all,
Its my first DRSSTC play tubular bells midi

Half Bridge IXGK60N60C2D1 IGBT (same to IXGN60N60C2D1 but TO-264 package)
Bus voltage 170 volt AC (240 volt DC)
MMC - 0.1 uf 4000 v ( 2 serial + 2 parallel 0.1 uf 2000 v polypr.)
Primer 6.2 turn 12 cm dia @ ~200 khz
Seconder 0.2 mm enamelled chopper wire ~1650 turn, 75 mm PVC pipe 38.7 cm long ~215 khz
Driver UD1.3
Topload 4.5 x 38.5 cm toroid
Spark 35-40 cm but not full tuning.


Now, i build new driver like UD2.5 but fdd8424 or IXDD430MYI driver sellectable. Some problem with GDT and phase lead adj.

Offline erdal

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Re: My first DRSSTC
« Reply #1 on: September 21, 2018, 10:11:39 AM »
I'm sorry for my bad english
I have some problem with phaese lead adjust and gate driver signal.
I connect 200 kHz to the FB input with 555. If I don't give bus voltage, an excellent square wave gate signal is generated. But if I connect bus voltage or/and connect ct to fb, the gate signal is distorted and +-40 volts rise.
I use 5.1 ohm gate resistors and 1n5819. i tried three different gdt

My other problem, i cant adjust phase lead. try coilcraft 123 and 153 coil. Always dangerous high spike at output IGBT

I will send oscilloscope pictures

here is my driver board

testing;

Offline erdal

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Re: My first DRSSTC
« Reply #2 on: September 21, 2018, 06:38:51 PM »
Can one of you help me? :))

555 drive 200 khz FB input. Gate to source waveform. No bus voltage


Normally operation, 170 v dc bus voltage. Gate to source


Halfbridge one IGBT drain to source


interesting, oscilloscope 50v/div to 100v/div. Changing waveform???


Offline Mads Barnkob

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Re: My first DRSSTC
« Reply #3 on: September 21, 2018, 10:05:28 PM »
Hi Eldar and welcome to HVF

Please read the site rules about double posting: https://highvoltageforum.net/index.php?topic=31.0

For trouble shooting your GDT waveforms, be sure to check out: http://www.richieburnett.co.uk/temp/gdt/gdt2.html

Who made that red UD3.0 driver board? You mentioned UD2.5?

UD1.3 is a sturdy little beast and can drive almost anything with large disturbances and unbalances. The phaselead UD's from 2.1 and up are however much more sensitive to excessive energy in the system and therefore it is often needed to have a 1-2K power resistor across the inverter output to remove any residual charge that will ruin the oscillation feedback.

The large spikes you are talking about is that on the inverter output or on the IGBT gates? If you are testing at low DC bus voltage, the switching spikes will look very large compared to the DC bus voltage, but fear not, it is just the output capacitance of the IGBT playing a game with you, these spikes only look big because you test at low voltage.
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Offline erdal

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Re: My first DRSSTC
« Reply #4 on: September 22, 2018, 12:35:39 AM »
Hi Mads,
thank you for your reply and sorry for the double posting  :-[

Quote
Who made that red UD3.0 driver board? You mentioned UD2.5?
Me :)
based on ud 2.5, some minor placement changes, I've canceled the second output (fdd8424 and UCC's), I've added the IXYS IXDD430 gate drivers instead. (IXDDs have low voltage protection and its 30 amps)

Quote
The large spikes you are talking about is that on the inverter output or on the IGBT gates?
Inverter output
 
Quote
The phaselead UD's from 2.1 and up are however much more sensitive to excessive energy in the system and therefore it is often needed to have a 1-2K power resistor across the inverter output to remove any residual charge that will ruin the oscillation feedback.

Hmm... I've tried it and have a better waveform :)
maybe it's because I went from cola to beer :))

Offline profdc9

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Re: My first DRSSTC
« Reply #5 on: September 22, 2018, 04:03:01 AM »
With the board I built that uses phase lead, without placing it in a metal box, and putting chokes on the transformers coming into the circuit board, the board was very susceptible to noise as it is placed right under the tesla coil.  I choked the power supply cable, the gate drive transformer, and the current sense transformers, and had an aluminum box around the circuit as well, though I could operate it with the top off when tuning with relatively low bus voltage.  You can make a simple choke by getting a ferrite toroid, twisting the two leads together, and wrapping the leads several times around the toroid.

The phase lead inductor coil I used was not shielded so it probably was picking up some magnetic field from the tesla coil itself, as it is basically behaves like a ferrite loopstick antenna similar to those used in AM radios.  This is one reason having a good metal box around the circuit is critical.

Dan

Hi Mads,
thank you for your reply and sorry for the double posting  :-[

Quote
Who made that red UD3.0 driver board? You mentioned UD2.5?
Me :)
based on ud 2.5, some minor placement changes, I've canceled the second output (fdd8424 and UCC's), I've added the IXYS IXDD430 gate drivers instead. (IXDDs have low voltage protection and its 30 amps)

Quote
The large spikes you are talking about is that on the inverter output or on the IGBT gates?
Inverter output
 
Quote
The phaselead UD's from 2.1 and up are however much more sensitive to excessive energy in the system and therefore it is often needed to have a 1-2K power resistor across the inverter output to remove any residual charge that will ruin the oscillation feedback.

Hmm... I've tried it and have a better waveform :)
maybe it's because I went from cola to beer :))

Offline erdal

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Re: My first DRSSTC
« Reply #6 on: September 22, 2018, 06:15:07 PM »
I guess, I solved most of my problem ;D
Reduced GDT winding, 15 to 13.
IGBT gate to source signal, insignificant miller effect and some noise.
I think it gets better with profdc9 advice
Quote
You can make a simple choke by getting a ferrite toroid, twisting the two leads together, and wrapping the leads several times around the toroid.

I increased the windings of feedback toroidals and used a larger toroid.
I'm now using T130-26 in 1/625 ratio. Can now adjust phase lead.

Is the voltage collapse in this picture important?

I put UD in aluminum box

After that, my DRSST-II will be full bridge, DRSSTC-III IGBT Bricks :)
Thank you for your help :))

Edit: image add attachments
« Last Edit: September 24, 2018, 09:48:14 AM by erdal »

Offline profdc9

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Re: My first DRSSTC
« Reply #7 on: September 23, 2018, 05:07:15 AM »
The gate driver transformer is typically bifilar wrapped around a ferrite core NOT an iron powder core (there's a difference).  T130-26 is a micrometals iron powder material typically used for power inductors with a permeability of 75.  It's designed to be a low-loss inductor, and is not as good as a transformer core.  Most MnZn ferrites are have permeability typically in the thousands.  A good toroid would be something like a FT82-77 should be sufficient.  It has a permeability over 2000 and is good up to a few MHz.  But there are many materials that would work, also a FT82-43, even though it has a permeability of only 850, is ok too.  And it must be wound bifilar to have good magnetic coupling between the primary and secondary turns.

Dan

Offline Mads Barnkob

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Re: My first DRSSTC
« Reply #8 on: September 23, 2018, 07:32:39 AM »
Good catch Dan, that sure could be the culprit for skew and distorted waveforms.

Generally I just use the same material, in varying sizes for both GDT and CT.

I used Epcos N30 material ring cores, Aemm^2: 95,89, AL: 5750nH for my DRSSTC1, I do not have the exact part number
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Offline erdal

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Re: My first DRSSTC
« Reply #9 on: September 23, 2018, 05:30:11 PM »
I used cosmo ferrites CF199 (ui = 9000) in some other projects for GDT. (low frequency ~50 -100 khz, induction heater, SMPS, Inverter, Welding machine eg.)
I've read a lot about working better at the big Al in GDT. When it comes to ferrite, it is necessary to increase the core diameter or the number of turns.
In this project, I tried Ferroxcube Tx 40/24/16 3E27 (like N30), Cosmoferrites 36/21/15 mm CF199, 49/32/19 mm CF197 type materials for GDT.

But I would have to take into account your experience that ferrite material is better at high frequencies or drsstc. (for GDT)

I can try ferrite material for the CT, but unfortunately I don't have enough (I have five 49x30x20 PC40, one 63x38x25 N87)  ferrite material in my hand or at the local dealer. I will have to order from other countries :(

Many thanks for your advice and comments. Tomorrow, I watch a little sparks that connects the secondary coil :))

Oscilloscope images of my last settings are below. I guess as it happened

No phase lead: pict1

With Phase Lead (Coilcraft 7M153 too high, min. adjust still some spikes. I try 7M123): pict2

GDT seconder output: pict3

Edit: image add attachments



« Last Edit: September 24, 2018, 09:50:25 AM by erdal »

Offline profdc9

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Re: My first DRSSTC
« Reply #10 on: September 23, 2018, 11:11:05 PM »
What determines the number of turns is the impedance of the load.  At the frequency of use, the impedance of the coil must be greater than the load, so that the primary side coil should have an impedance much greater (3-4 X at least) as the driving impedance, and the secondary side should be much greater than the load impedance.  A IGBT or MOSFET gate is a capacitor and actually a fairly low impedance.  You can always increase the number of turns, assuring that the impedance of the coil is higher than the mosfet gate, but the leakage inductance increases as well.  A bifilar winding will make the leakage inductance very low and this should not be a problem.  Take two different color wires, twist them together, wind them together around the toroid perhaps 10 times, and then you have a 1:1 transformer with one color wire being the primary and the other the secondary.  It's very simple to do right once you have the right material.  Make sure the insulation on the wire is good for at least 600 volts, so sometimes teflon wires are used, because the insulation is thin reducing the leakage inductance, but maintains a high dielectric resistance. 

Dan

Offline erdal

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Re: My first DRSSTC
« Reply #11 on: September 23, 2018, 11:53:16 PM »
Hi Dan,
Here is my GDT's. First CAT5, all bifilar winding but hi initial permeability iron core. (6000 to 9000) They all have similar results. I will also experiment with ferrite core on your suggestion

Now i have better result with phase lead. First image no phase lead, second with adjut phase lead.

Edit: image add attachments
« Last Edit: September 24, 2018, 09:52:40 AM by erdal »

Offline Mads Barnkob

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Re: My first DRSSTC
« Reply #12 on: September 24, 2018, 09:03:11 AM »
Erdal, I am getting "403 Forbidden" on all your image attachements, is it just me?
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Offline erdal

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Re: My first DRSSTC
« Reply #13 on: September 24, 2018, 09:54:20 AM »
Hi Mad,
pictures add attachments
thnx

115 v AC MIDI testing. 30 cm spark to grounded bar. OCD have set 300 amps, but it's not activated.


230 v AC, low BPS testing. 45-50 cm sparks.  my toroid started to throw sparks randomly because of the sharp corners. I didn't ride BPS because I was afraid that the rail wasn't a strike rail and the inverter was working outside.
« Last Edit: September 24, 2018, 12:25:39 PM by erdal »

Offline profdc9

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Re: My first DRSSTC
« Reply #14 on: September 24, 2018, 05:39:01 PM »
Your GDTs look ok, they are probably ferrite toroids if they are black and have a high permeability 6000 to 9000.   I am not sure what kind, but it's probably ok as it is.  It can be a problem at the higher frequencies if the ferrite has too low of a bulk resisitivity.  You can tell this because you can take your multimeter and measure the resistance between two nearby points on the toroid perhaps a few mm apart and you will see that it reads in the 10 to 1000 kohm range.  Higher is better, but with MnZn usually higher permeability means low resistivity, so there's a compromise.   Really high permeability 8000-10000 is usually used for low frequency (<100 kHz) switching power supplies, while permeability 1000-3000 is used for medium frequencies (100 kHz to 1 MHz).  The 77 mix is good up to 1 MHz, but the permeability is lower than what you have, but if you are using CAT5 twisted pair the leakage inductance shouldn't be a problem.  At any rate, if it's working, don't mess with it.

Dan

Hi Dan,
Here is my GDT's. First CAT5, all bifilar winding but hi initial permeability iron core. (6000 to 9000) They all have similar results. I will also experiment with ferrite core on your suggestion

Now i have better result with phase lead. First image no phase lead, second with adjut phase lead.

Edit: image add attachments

Offline erdal

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Re: My first DRSSTC
« Reply #15 on: September 24, 2018, 08:05:33 PM »
GDT and CTs now seem to be no problem. But I have a new problem :)
My MMC bank's failure..!
I use polypropylene snubber caps 0.1 uf /2000v each total 2 serial + 2 parallel 0.1 uf 4000v DC.
Two of the four capacitors are short-circuited. I think, dielectric material is drilled due to high voltage. I Plan to design the new mmc bank 3 serial 3 parallel total 0.1 uf 6000 v.

I measured primary and secondary. Approximate values with javaTC

pirates of caribbean, OCD 300 amper, runing 230 v AC main


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Re: My first DRSSTC
« Reply #16 on: September 25, 2018, 08:59:05 AM »
I just ran your MMC numbers in: http://kaizerpowerelectronics.dk/calculators/mmc-calculator/ using the number from: http://www.europowercomponents.com/media//k/p/kp-6_-_snubber_capacitors__1.pdf

and with 2 in series 2 in parallel, you are running with a way too low RMS current rating for your MMC and you properly cooked them to death :) even with the Irms rating for 100 kHz it is bad, so its even worse for 200 kHz.
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Offline erdal

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Re: My first DRSSTC
« Reply #17 on: September 25, 2018, 03:01:10 PM »
Hi Mads,
thank you, your MMC calculator very usable but my caps not in there :( I've placed a new order for the MMC. I use 4 parallel 3 serial total 130 nf 6000v. 36 amps rms.  940C20P1K-F is 4.88 usd at mouser, Alcon KP6 only get 1 usd and will be tomorrow in my hand ;)

I'm about to complete my new full bridge inverter. I hope that will create 1 meter spark on the full bridge. I did a new GDT. PC40 MnZn ferrite material (ui=2300)
have a nice day :)


Offline erdal

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Re: My first DRSSTC
« Reply #18 on: September 26, 2018, 02:58:25 PM »
Yeah, full bridge amazing!
I have tried 115 volt ac at 275 A OCD. Great sparks. (I couldn't take nice picture)
My new mmc group 4 parallel 3 serial total 125 nf (I measure) 6000 volts. I reduced the number of windings to 5.2 to set the primary resonance

Now, Seconder is 210 khz, Primer is 187 khz. 

IGBT's: 4 x IXGK60N60C2D1
Bus Cap: 2200 uf 400v Kendeil
Bridge diod: 50 amp. 1000v
Primer: 5.2 turn 12 cm dia 6 mm2 copper wire
Seconder: 0.2 mm enameled copper wire ~1650 turn (38.5 cm long) 7.5 cm dia PVC tube
Topload: inner 4.5 cm, outer 38 cm toroid

low BPS 115 ac video here;
« Last Edit: September 26, 2018, 03:22:23 PM by erdal »

Offline Mads Barnkob

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Re: My first DRSSTC
« Reply #19 on: September 27, 2018, 08:10:46 AM »
You just have to fill in your own capacitor specifications in the MMC calculator, I think I will make a video on how to use the calculator because it might not all be obvious :)

You get some good progress going and make sparks is key!

You need a tap able primary coil so you can tune the frequency of the primary circuit more precisely, the sweet spot is within a few centimeters, so its necessary to have large blank surfaces to tap on. If possible, find another place to test your coil, the very close proximity of the wall can make tuning it harder and once you move it out into a "free air/space" area the tuning will not be good anymore.

Did you try to add such close proximity walls in JavaTC? It has a really big effect on the secondary circuit resonant frequency.
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Re: My first DRSSTC
« Reply #19 on: September 27, 2018, 08:10:46 AM »

 


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