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Messages - Teravolt

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1
you might be able to find where the spikes are comming from by finding out what edge or operation they are synced to. you also may have stray inductance in your connections that are feading into the driver

2
If you want to try more dampening going from each half bridge to ground say 1000 to 220 you will have try it your self. the last wave form is much better and when you get the spikes and overshoot under controle you might slowly decrease your dead time to something less to close the time at zero volts. you should be able to see on the scope as you are addjusting. Things may change when you add your resonant primary and feed back so go slow and monitor safely if you can whyle you see what happens when you turn up the voltage to see if the spikes get bigger.

3
it looks good. I agree 1.5uS is a little to much, how about 1uS, is it adjustable? hear in the US we or I have 220vac with a center taped ground and typically builders use a full wave capacitive doubler to boost the voltage but I'm looking at your setup closer and I am assuming you have 220Vac with no center tap and you are running rectified mains and the big caps are your filtering and energy storage. have you tried firing up the bridge with a isolation transformer and variac? in a answer to your question about adding some dampening resistance at the output to a center taped junction ignore that. I was able to reduce the over shot on my bridge by adding non inductive resistance to a stiff reference. In your case I am not shure where to do that or even if it is necessary. have you tried adding the primary circuit and using the feed back yet? when you do start at a low mains voltage and monitor as raising the voltage watch for to much overshoot and cross conduction

In a note for your future builds I would have put the ADuM1200CR next to the UCC ic instead of separating them with a twisted pair and use a TTL A-drive and B-drive signals in coax, ie BNC. About using 2 different half bridges as long as your dead time covers the slow brick I think you will be ok. keep the pictures coming if you have questions. just remember that you are doing something that tesla enthusiasts don't usually do but because of its complications is done in the commercial arena all the time.

4
Hi Vaclav, the picture, gate 4, has a lot of noise I think remove the 2k's that you have added and add 2k from IGBT gate and emitter and see if that helps. to my knowledge not many people hear have tried to do direct drive and usually uses transformers. I have seen this before. also try adding incrementally resistance say 2k 2w temporarily across 1/2 of the bridge output to the center tap of mains multiplier capacitors. The idea is to add a mild resistive loading to your bridge output to the center tap of the capacitors to damp transient noise generated by emi. If you look at your blue gate signal the transients are synchronized with your transitions if the IGBTs. this also can be caused by not enough dead time. I have tried what your doing with good results but I wanted to reduce the complications of lots of circuitry so it can easily be reproduced I have outlined this in my thread

https://highvoltageforum.net/index.php?topic=632.0

Using direct drive I think IGBT transition times small enough to use bricks up to 100khz out side normal operating frequency, also phase manipulation or PWM is more possible

5
hi there Vaclave, I like your design however I am with Netzpfuscher. dump the mosfet driver fets and the bootstrapping unless you can make it work. the UCC's will drive each igbt directly for short periods. I am not completely clear on your circuit because it is kind of broken up and hard to get a clear picture. I am assuming that the ADuM1200 are for galvanic isolation and they are driving the UCC's? (That would be my choice.) I have tried this with the

https://www.nve.com/Downloads/il710.pdf

and using them to drive

https://www.digikey.com/product-detail/en/ixys-integrated-circuits-division/IXDD614CI/CLA356-ND/2424696

with isolated supplies

https://www.digikey.com/product-detail/en/murata-power-solutions-inc/MGJ6D051505SC/811-3229-ND/6202202

later I ended up using

https://www.infineon.com/dgdl/Infineon-1EDI60N12AF-DS-v02_00-EN.pdf?fileId=db3a3043427ac3e201428e5da08f372a

to me I see a lot of shoot through at your driver scope shots. make your leads to the gates as short as possible and add dead time at u3c and u3d

 http://www.modularcircuits.com/blog/articles/h-bridge-secrets/h-bridge-control/

I hope that I have not overstepped on your thread. I am interested in what you are doing do you have a topside picture of your driver box

6
Its good that you found a friend to help you just remember to use some sort of isolation transformer if measuring the primary circuitry while measuring. it can be dangerous with out the respect of the 220vac where you live. let us know of your progress and if you or your friend want to ask questions I am shure somebody will help.

7
I think it is worth fixing. there has been many discussions about cheep chines mosfets and just replacing them may be an issue because even though the fets have the same number and logos printed on them the actual die in the device is different. The image that I have picked has 2  what looks like mosfets and a bunch of diodes surrounding the devices. have you used your multimeter in the diode mode to verify that none are shorted specially the transorbs next to the red wire. Does the tesla have 2 or 4 fets, these are the bridge fets that convert the rectified line voltage. this will be the dangerous part of the tesla and if you are not comfortable probing this you will need someone that is. The object is to determine if your mains rectifiers are good and that you have your mains dc filtered voltage present. It looks like a full wave doubler is your voltage source to the tune of plus and minus 311Vdc at your line voltage. Because you have about 622Vdc your fets will have to be 1200v. this may be the problem why it died. What is the number printed on your fets? I would try something like

https://www.ebay.it/itm/ON-Semiconductor-NGTB40N120L3WG-IGBT-160-A-1200-V-3-Pin-TO-247/163124118740?hash=item25faf484d4:g:f1MAAOSw5ItbNloq

or

https://www.ebay.it/itm/1-pc-IXYH82N120C3-IXYS-IGBT-1200V-200A-1250W-TO247AD-NEW-BP/232735336094?hash=item36301b669e:g:MFAAAOSwq7JT3ARH

I go by max power rating at 1200v. Italian EBAY is kind of the wild west because I don't see pictures of what you re getting and some of these parts are from Germany. hopefully more will chime in hear to help you. Do you have all of your power voltages on your driver board like the 5v 12v 24v ect.

8
So the good news is that it can be fixed the bad news is that it will take a tecnition and equipment to repair it. what is your skills with elecronics and what kind of equipment do you have. A good tecnition may even be able to perminatly fix it. with an oscilloscpoe you would be able to evaluate it for us to understand where the problem is. I suspect that your pimary section is still not fixed this includes the H-bridge and the drive comonents and your primay capacitors. Do you have pictures of the guts of the unit?

9
invest in a isolation transformer so you can connect your scope common to your power sources common. reserch so you understand what you doing. I just use a dual winding 120 to 120 transformer. it does not have to be a expensive topaz transformer just something to seperate your mains refrance to ground. if you have 220 the same applies. it will be cheaper than a diferencial probe

10
hello VNTC and Uspring, yes Uspring you are right that a tesle wave length or resonant frequency can not be carictorized by wire length however it will still behave like a 1/4y or 1/2y antena depending what type of tesla is built . I have never herd of a 3/4y or 1 1/4y tesla.
my understanding is that when we tune a tesla it is for a 1/4y because we want maximuim voltage at the top and max current at the bottom.

my point is that there are 2 types of capacitance to determin resonant frequency.  they are the paracitic capacitance between each winding and the top capacitance with the earth. what I have found from seeing this myself and form others that paracitic capacitance is not desireable and that capacitance is. By adding capcitance with the earth as series tank whitch is what you want to create voltage at the node where the cap and inductor connect we do this with a DRSSTC primary because the voltage is peak whare the MMC and primary connect. Not only can a DRSSTC be tuned at its primary but buy adding more torides where it makes it behave more like a 1/4y antena than a tank circuit


11
hi Uspring I agree with everything you are saying but I have found that if you are in space and you strech your wire out it as a quater wave length and then put back the quater wavelength will be lengthend by the added destibutive capacitance and top load capacitance by a factor of what I dont know.  by using the 1/4y method you can ballpark a teslas top resonant frequency. crtanly if you more turns and or smaller wire this afect is larger. I have tested this out with short tesla,12x6" inductors with 20awg wire and I can almoast get the resonant frequency. I thought the the tesla has always been considered a 1/4 wave to get the high voltages at the tip thus I think it is a type of antena. corect me if I am wrong but antenas are usaly tuned circuits.

12
hi there VNTC, have performed these expieiments before to. my goal was to increse the Q of the secondary circuit. like you I wanted to make a secondary frequency that I wanted around 500khz so i decided to make it with a lengt to diamiter ratio of about 2:1 so with a 4" tube it was about 10" high. I did this to reduce distibutive capacitance. distibutive capacitance is in parallel with the secondary inductance witch would be great for a parallel tank. by adding torides to the top it makes a more series resonant tank circuit witch is what we need for voltage amplification. having said that I found the wave length of 500 Khz and derated it because all the extra capacitance that was being built into it will decrese the resonant frequency. I guessed at what this may be about 15% lower. eventualy I got it in an accepible range for sword sparks. for me adding capacitance to the top increases the topload voltage. others may have seen or expieinced this and may be able to eplain it more clearly. I found a good websight for a better explination. it doesn't refer to teslas bu tank circuits and a tesla is a tank/antena circuit. check out Series Resonance Example No1

https://www.electronics-tutorials.ws/accircuits/series-resonance.html

13
Dual Resonant Solid State Tesla coils / Re: QCW music with Midi
« on: May 09, 2019, 06:29:36 AM »
I don t care much for transformer circuits because when they don't work they are a bitch so went to developing isolated drive circuits. The infinium driver and murata dc to dc power supply were almost made for each other in that I can drive IGBT's or MOSFETs with -5 to +15 with about 2 ohms. This makes the rise and fall times fast in the 100ns times. It depends on how much capacitance is in the gate. The drivers also have sub nano second internal delay reducing your feedback to switching time thus hopping I wont have to use a phase lead circuit at the feed back input. With direct drive I can switch the MOSFETs with a TTL input and control timing, phase, dead time, or a microprocessor.

my earlier versions used quad isolated power supplies consisting of a transformer, raw dc and a 15v regulator. very easy to make for about 100$us. With that I used HFBR-2522Z fiber optics or magnetic isolator, IL710, to isolate my signal and drive a IXDD614CI or even a 30A IXDD630CI. With those FETs and IGBTs can be driven with 1-4 ohms and bipolar voltages if thought about. This can also get 100s of nano seconds or less of rise and fall times

I want to set this up to drive a bridge of IXYH100N650C3 200A 830W FETs for the DRSSTC at about 400-500KHz I made the setup I just need test and implement which will follow the D amplifier. This may take some time but I think I know what has to be done.

14
Dual Resonant Solid State Tesla coils / Re: QCW music with Midi
« on: May 04, 2019, 11:49:56 PM »
to whom may be interested, I am working un a buck converter slash class D amp and I am interested in reproducing

/>
now I know there was much talk about this video but I want to try doing this in a CW mode or near CW mode using something like this

https://www.arturia.com/microbrute-se/overview

so I have built the traditional D-amp with the ramped waveform but why not use an audio source instead of a ramped wave. with the circuit that I am working with I should be able to input a audio input. Typically a FPGA or microprocessor this might be a easy task buy phase shifting the DRSSTC bridge but I am not very proficient with software so I am taking the low road going analog. The amp that I built has a bipolar output vs. the typical 0v-300v volt ramp for twice the voltage. one of the hertals is building silicon IE bridge that can handle the average power that it might take. instead of using transformers I am doing direct drive witch is not usably done hear because of the set up for this. to do this I am using a

https://power.murata.com/pub/data/power/ncl/kdc_mgj6scdc.pdf

as a isolated power source and I isolated driver

https://www.infineon.com/dgdl/Infineon-1EDI20N12AF-DS-v02_00-EN.pdf?fileId=5546d4614755559a014790299add6112

originally I was using a quad power supply but I have managed to condense it using these components.
they are  driving 2 of these Semikron- SKM 400GB 123D , 400A, 1200V bricks with a fall and rise time of about 130 ns.
I am writing this article to show other ways to drive FETs or IGBTs other than using transformers as well seeing if any one is interested in my work.

the picture of the schematic is my current version that I am working on and the breadboard is what it looks like at some point I am going to solder it together. the other pictures are of the current way it looks

for the filter I kind of flowed

 https://www.loneoceans.com/labs/qcw/

but I used a Yellow core instead of a red core witch has a lower frequency response. The filter inductor has 2 windings wrapped in opposite directions and the pulse width signal from the half bridges are inverted to get a negative and positive ramp.

if any one is interested the tesla that I am working on is 500khz so the sword sparks can be achieved

http://www.seventransistorlabs.com/ClassD1/

so another current interest and that I want to try is synthesized music and my goal is to merry the beat step with the tesla

 


this project is on going and in depth and I am trying to see if any one has tried this or is interested

15
Dual Resonant Solid State Tesla coils / QCW music with Midi
« on: May 02, 2019, 09:34:12 PM »
I would like to be able to play midi notes into a QCW and I am looking for a way to convert a computer keyboard or synthasizer key board or sequencer. I am presantly designing the QCW to accept an audio input into a 300v class D amp. I am not shure how well this will work. the amp will be able to very in amplidude as well as frequency to apply to the power of a QCW. all inputs are welcome

17
Dual Resonant Solid State Tesla coils / Re: DRSSTC no sparks
« on: April 24, 2019, 09:38:41 PM »
is the phase correct from your feedback transformer going into the univesal driver. have you tried feeding a sqare wave into the feedback input with a low voltage at your mains cap to see if your gate drive and bridge is working as expected? once you get that sorted out you can see if your feedback transfromer is coupling the current properly into a resistive load

18
Spark gap Tesla coils / Re: How many Farads should my bank have?
« on: April 22, 2019, 11:37:35 PM »
the question is how much capacitance is in 1 bottle what is the inductance in your primary and what is the resonant frequency in your secondary with topload toride. how many bottles will it take with your primary inductance to make your primary equal to your secondary frequency. caps in parallel add so you will have to make some mesurements and your flyback may have enough energy to make 2-3" sparks if you want more you will need more power.

https://www.daycounter.com/Calculators/LC-Resonance-Calculator.phtml

19
Dual Resonant Solid State Tesla coils / Re: DRSSTC no sparks
« on: April 22, 2019, 07:30:18 PM »
that last waveform has a phase inversion baby there is something wrong with your feadback coil. do the primary and secondary have the same resonant fequency?

20
Dual Resonant Solid State Tesla coils / Re: My first DRSSTC on bricks
« on: April 22, 2019, 07:24:49 PM »
Hi Laci, are your mmc caps soldered to the aluninuim because leaded solder will not flow on aluminuim and you may have a bad connection. get some copper wire or tubing or brass and solder to that.

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