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OverUnity Research > Benches > Peterae (Moderator: Peterae) > Controller No5 With Protection - Looking for Explosions
2024-11-26, 11:54:34
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Author Topic: Controller No5 With Protection - Looking for Explosions  (Read 231571 times)
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img  verpies
Re: Controller No5 With Protection - Looking for Explosions « Reply #325 on: 2018-10-23, 10:23:37 »

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Quote from: Itsu on 2018-10-22, 15:26:15
(it off course verywell could be that thats the reason he saw them as after boxing up Peters box my crackling sounds stopped).
If it is Meyer related, then perhaps the external magnetic field on your bench changed after the boxing.
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #326 on: 2018-10-23, 11:52:00 »

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Meyer,  as in Stan Meyer?  Not sure, perhaps Peter knows.
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #327 on: 2018-10-23, 13:21:36 »

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Buy me a cigar
Hi Itsu.

I think Verpies is referring to the Meyer/Mace device.

https://tesla3.com/meyer-mace-michel/

Cheers Graham.


---------------------------
Nanny state ? Left at the gate !! :)
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #328 on: 2018-10-23, 14:27:07 »

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Aha Graham,  thanks, i do see some similarities.


Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #329 on: 2018-10-23, 20:53:19 »

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I decoupled and choked the hell out of my voltages, but still i got the ripples on the FG input signal and
Q1 gate signal after applying voltages to the setup.

I did notice that the ripple started when attaching the scope probe, so i went over using these RF like probe tips
see picture.

Now the signals cleared up a fair bit, see screenshot from REF1 (FG input signal) and REF2 (Q1 gate signal).

I used the white REF signals as its a 4 hands business now to probe 4 channels and i thought i could do it pair
by pair, but i lost the trigger point, so the signals (pair by pair) are not in sync anymore.

Are there any specific 2 signals you want to be shown?
Else i need to come up with a trick to use the 4 probes with RF tips all together.

I now lost the 10 ohm resistor, so need to find a higher wattage one.


Regards Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #330 on: 2018-10-24, 07:04:32 »
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 8)
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #331 on: 2018-10-24, 09:27:54 »

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Aaah,  the third hand,  nice trick   O0
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #332 on: 2018-10-24, 16:00:41 »

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I was able to use my 4 probes with RF tips to capture:

yellow: FG input
blue:   Gate Q1
purple: Drains signal
green:  Gate Q2 @ 1K load.

Using a IXDD614PI at 20V and 42V on the drains of the IRFP460's.

1st screenshot is at 40ns/Div,
2th screenshot is at 2us/Div.


Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #333 on: 2018-10-25, 01:40:42 »

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That was a difficult probing setup.
Lets see how it looks when the load of Q2's gate = the driver's impedance that drives Q1's gate.

...but before that, it is unacceptable that Q1's gate signal (blue) does not follow the yellow input signal from the FG (40ns of propagation delay is fine but the lack of ANY inkling of a blue falling edge 80ns later -  is not). 
There is an inkling of a blue falling edge over 200ns later, but that is not only a huge asymmetry in the propagation delay between rising & falling edges, but >200ms is an unacceptably long delay, by itself!
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #334 on: 2018-10-25, 09:53:44 »

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So what you are saying is that the "inkling of a blue falling edge over 200ns later" really should be there after only 80ns.
So it seems that the MOSFET (gate) is somehow smearing out the signal it receives.

If that's due to the IRFP460 Ciss of 4.2nF, then i could try a FQA11N90C which only has a Ciss of 2.5nF (Typ).

Itsu
« Last Edit: 2018-10-25, 10:31:22 by Itsu »
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #335 on: 2018-10-25, 15:39:27 »

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As mentioned earlier in another thread (http://www.overunityresearch.com/index.php?topic=3655.msg69985#msg69985),
i received some crappy IXDD614PI driver chips from China which could not withstand the 40V Vcc (magic smoke at 27V).

They now turned out to also be crappy in other area's like the smeared out gate signal shown above.

I received a new batch IXDD614PI's from Mouser and not only they can withstand the 40V Vcc, but the Gate signal looks
very different from the crappy ones, see screenshot 1 below.

In white the FG input signal (Ref1) and Q1 gate signal (Ref2) from the crappy one, and yellow / blue the same signals from the good one.

We now do see an "inkling of a blue falling edge 80ns later".


The 4 signals together with the good driver now show as in screesnhot 2 and 3

yellow: FG input
blue:   Gate Q1
purple: Drains signal
green:  Gate Q2 @ 1K load.

Using a IXDD614PI at 20V and 42V on the drains of the IRFP460's.

Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #336 on: 2018-10-25, 16:21:40 »

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Reducing R4 from 1K to 222 Ohm kind of flatlines the green trace (across r4) around zero before and after the Q1 gate signal, see screenshot.

Guess thats "how it looks when the load of Q2's gate = the driver's impedance that drives Q1's gate".

Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #337 on: 2018-10-25, 20:58:01 »

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Same setup as above, but now with 2x FQA11N90C MOSFETs in  (R4 = 1K).
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #338 on: 2018-10-26, 19:53:59 »

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It is amazing how crappy the previous drivers were!

Quote from: Itsu on 2018-10-25, 15:39:27
We now do see an "inkling of a blue falling edge 80ns later".
Indeed we do

Quote from: Itsu on 2018-10-25, 16:21:40
Reducing R4 from 1K to 222 Ohm kind of flatlines the green trace (across r4) around zero before and after the Q1 gate signal, see screenshot.

Guess thats "how it looks when the load of Q2's gate = the driver's impedance that drives Q1's gate".
I am surprised, that the driving impedance is around 220Ohm.  I would expect teen or single Ohms for these tens of nanoseconds wide pulses.

If R4 is too large then Q2 latches on until its gate charge leaks out.

It is good that the green trace (across R4) flatlines. This trace should look approximately like the 1st derivative of the drain voltage (purple trace) - it shows the charge injected into the gate by the Miller current....for Q2 and for Q1.
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #339 on: 2018-10-26, 20:20:50 »

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Quote
It is amazing how crappy the previous drivers were!


yes, i am amazed too, this is the first time i notice something is wrong with parts.
Finding out that they blow up on half their rated Vcc voltages is one thing, but it takes a knowledgeable person to
detect such smeared out propagation as being unacceptable,  well done verpies!   O0


So that 220 Ohm R4 resistance means that the output inpedance of the driver is also around 220 Ohm?
The data sheets talk about output resistance of ±0.4 Ohm, so that 220 impedance comes ontop of that.

So in the original circuit from Peter, we need to match that 220 Ohm output impedance of the driver to the input
impedance of the gate somehow, right?


Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #340 on: 2018-10-26, 22:15:24 »

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Quote from: Itsu on 2018-10-26, 20:20:50
So that 220 Ohm R4 resistance means that the output inpedance of the driver is also around 220 Ohm?
The data sheets talk about output resistance of ±0.4 Ohm, so that 220 impedance comes ontop of that.
Yes, 220 ±0.4 would be the total

...but I am kinda lost where that 220 Ohm comes from.  I did not read the entire thread but the gate resistors (R3 and R4) in this schematic seem to be 3 Ohms.

3 ±0.4 would make much more sense at these pulse widths...
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #341 on: 2018-10-27, 09:54:30 »

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Yes, the R3 and R4 are around 3 Ohm.
The 220 Ohm comes from me measuring the green trace flatlining roughly to zero (from 1K).

It very well could be that when even further decreasing (to around 3 Ohm) the green trace will flatten out even more
or shape more according to "like the 1st derivative of the drain voltage (purple trace)".

I can check on that.

How about the capacitive reactance of the 4.2nF Ciss?
Could it not add to the total impedance?

According to: http://www.66pacific.com/calculators/capacitive-reactance-calculator.aspx

a 4.2nF capacitance (Ciss) at 170KHz has a reactance of 223 Ohm.

Can this 170Khz somehow be related to the gate signal pulse (rise / fall times) we have?

Itsu
« Last Edit: 2018-10-27, 10:38:14 by Itsu »
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #342 on: 2018-10-28, 11:12:53 »

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Quote from: Itsu on 2018-10-27, 09:54:30
a 4.2nF capacitance (Ciss) at 170KHz has a reactance of 223 Ohm.
For pure sine wave - yes, but for square waves the reactance is 19% smaller ...and for rectangular waves it depends on the duty cycle.

The purpose of the Miller test circuit is to see how a Miller current influences the gate voltage during switching, so R4 should be the same as the driving impedance of Q1's gate.
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #343 on: 2018-10-28, 21:26:06 »

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Ok,  but can we do something with that knowledge (R4 should be the same as the driving impedance of Q1's gate), or is it just "nice to know"?

Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #344 on: 2018-10-29, 21:20:00 »

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Meanwhile i have been running Peters box/setup again on all kind of phase, frequency and pulse width combinations/sweeps
for the last week or so, but not a single crackle was detected.

Today i removed the back shield from the box and let it run the whole evening again in all kind of combinations, but
still not a single crackle was noted.

Not sure what to do next

Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #345 on: 2018-10-30, 19:27:49 »

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Buy me some coffee
are you driving a single coil with the 2 fet channels or a bifilar with the 2 channels. ?
I mostly stuck with IRF840 Fets
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #346 on: 2018-10-30, 19:58:14 »

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Driving a bifilar with the 2 channels.

Yes, i was planning to go to IRF840's, lets see how they behave.

Itsu
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #347 on: 2018-10-30, 21:27:10 »

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tExB=qr
I don't believe there was ever any magic to  the compressed pulse produced by the bifilar (one channel delayed about 220ns). 

It was just a means to produce a high voltage pulse.

Crackling and explosion sounds are exciting, but that's all.  The explosion sounds with 10kv are like a rifle shot.
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #348 on: 2018-10-31, 09:24:03 »

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Thanks,   

i try to figure out why suddenly after boxing up Peters box the crackling stopped.
I changed to IRF840's now and tossed out the (crappy?) IXDD604 driver for a new Mouser ordered one and things look better now (noisy).

Need some further tests.......Itsu 
   
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Re: Controller No5 With Protection - Looking for Explosions « Reply #349 on: 2018-11-01, 21:03:20 »

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Nope,  still nothing, running for 2 days with IRF840's and new 604 driver.

itsu
   
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