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Author Topic: Kapanadze Cousin - DALLY FREE ENERGY  (Read 9750559 times)

Offline verpies

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12600 on: March 08, 2016, 12:30:02 PM »
I See two kinds of frequencies across your drains. The first 14Mhz oscillation happens when mosfet stops conducting, and a second lower freq. oscillation to the same drain, when the other mosfet starts conducting. 
Looks like that between the two oscillations we have a change to the values...
That's Itsu's scopeshot?
Think of an experiment to verify that the open winding rings at a different frequency than the closed winding.

parasitic capacitance and leakage inductance which determine the oscillation value. I hope Verpies will through some light to the shade.
Yes, it is the leakage inductance that can form an LC oscillator with parasitic and stray capacitances.
The full winding inductance cannot form it, because most it is consumed by the "transformer action" (mutual inductance).

Is there any way for someone to predict the capacity value of a diode when this works in combination with a coil? I see for example that the diode bridge at the output of grenade, gives specific resonant rise to a frequency value according diode's capacity and grenade's inductance. Can this be calculated from the begin?
Yes but it is not easy.  Also note that any added parallel capacitance should decrease the frequency.  The bridge at the output loads the secondary and that can decrease the apparent inductance of the primary.  Less inductance there results in higher frequency.

Offline Jeg

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12601 on: March 08, 2016, 12:33:46 PM »

As mentioned earlier, i build a new yoke consisting of a T-520 Toroid using the loss-less clamp design with the same number of turns on the primaries (2x 12) and secondaries (3 and 28),
see picture were i compare the new toroid with the first one (not loss-less) i had.

When firing up, the 24V battery stack hits its auto fuse of 10A and thats it.

It seems that this "toroid yoke" gives way less inductance to the primaries (5.8uH each compared to the 64uH on a "yoke yoke") so it presents itself as a short to the MOSFETs.

I had the same effect as when i by mistake had wound my present loss-less clamp design yoke as bucking primaries, also then the inductance was too low and the 10A auto fuse came out.


So how to remedy this?   Use more turns on the primaries, but that will influence the secondary turn ratios as well which could cause the toroid to run out of space for all those windings.

Or stick with the present "yoke yoke"?


Itsu

Hi Itsu.
I guess your new core has lower permeability which makes it able to oscillate at higher frequencies than the yoke material. If in was in your place I would try a smaller cap at the output of your choke filter. I haven't try it but normally it will limit the inrush current. 
 

Offline Jeg

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12602 on: March 08, 2016, 12:58:50 PM »
Yes but it is not easy.  Also note that any added parallel capacitance should decrease the frequency.  The bridge at the output loads the secondary and that can decrease the apparent inductance of the primary.  Less inductance there results in higher frequency.

Thanks Verpies.
I am in changing my yoke today to a lossless one. Will it be any advantage if I use it in combination with my dissipative snubber? Won't it cut this way all this ringing that we see in Itsu's setup?



Offline starcruiser

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12603 on: March 08, 2016, 03:30:50 PM »
@ITSU,

Did you look at the specifications of the materials used in the cores you are using? The TV Yoke is designed to operate at a much lower frequency (Khz) than the standard torrid (typically Mhz or High Khz). TV Yokes are optimized to operate around the 15Khz area as this is the typical sweep rate (horizontal), the vertical is usually 30 to 60hz. I believe this is something most are overlooking when substituting cores in this project.

The test instruments to check inductance are using a low frequency signal (100Khz) to calculate the inductance. Ideally we should be using a frequency close to the operating frequency of the circuit to make sure the measured inductance is accurate.

Offline itsu

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12604 on: March 08, 2016, 04:44:09 PM »
The drain to source capacitance is more that 2pF.  The additional inter-turn capacitance would make it even higher.
But it is not the ~60μH that is ringing with this capacitance.  It is the much smaller leakage inductance which forms an LC tank with this capacitance.  The leakage inductance should be measured with the secondaries shorted.

So with these numbers the LC resonance of the leakage inductance seems plausible.
Good. That confirms that the 14MHz ringing comes from the drain circuit.

However that does not explain the 35.25MHz peak and the 9.416MHz peak with its harmonics.
Please repeat this test with a 100pF capacitor and note whether these peaks are also affected.
This means that the magnet forces the alternating magnetic flux out of the core, because the core forms a circular magnetic path and affecting any part of it would affect the inductance of both windings equally.

So that would be at the splits were i also have the stacked magnets.

Offline itsu

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12605 on: March 08, 2016, 04:46:55 PM »

Starcruiser,  Jeg,

yes, this T520-2 toroid is designed for HF use, see:

Al Values listed in µH/100 Turns
Permeability = 10
Frequency Range 2 Mhz - 30 Mhz
Color = Red
Inner Diameter: 3.080
Outer Diameter: 5.200
Height: 0.800
AL Value: 207


I hoped it would be more stable, but it seems i have to manipulate the turns ratio now.

Itsu

Offline magpwr

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12606 on: March 08, 2016, 04:55:01 PM »
hi everyone,

I have just uploaded video of my PWM generator running on 1xLi-ion battery (isolated/test supply) and working at 250VDC at 20% duty.

http://www.youtube.com/watch?v=cGRPKNhC_TE

The voltage across 3 turn on toroid is around 194Vpp at 1.5x Amps at 12.x Volts.

The 28turns behave like a NST running at 28khz and produce around 2kvpp.

I have not figured out what to do with this high voltage beside maybe running as spark gap tesla coil.(No plans for that) :D :D :D

I have finally implemented a varistor 80pf 620volts rated.This does not increase current draw at the power supply for inverter at all but merely serve as additional protection for the 1.2kv mosfet.
 

Offline Void

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12607 on: March 08, 2016, 06:34:38 PM »
I have just uploaded video of my PWM generator running on 1xLi-ion battery (isolated/test supply) and working at 250VDC at 20% duty.

Looks good Magpwr.

Offline verpies

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12608 on: March 08, 2016, 06:36:49 PM »
Thanks Verpies.
I am in changing my yoke today to a lossless one. Will it be any advantage if I use it in combination with my dissipative snubber? Won't it cut this way all this ringing that we see in Itsu's setup?
The lossless clamps only affect the drain signals above 2*VCC.
The dissipative snubbers should do that, too.  If they also affect the drain voltage below 2*VCC, then they are fighting the MOSFETs, because MOSFETs operate in this voltage range by design.  Fighting the MOSFETs is bad - it's like pressing both the car's brake and accelerator at the same time.
Note, that ringing below 2*VCC does not constitute a danger to your MOSFETs.

Itsu's ringing is primarily caused by the leakage inductance ...mostly.  Eliminate that with a proper winding and you will eliminate most of the ringing below 2*VCC.

Offline Void

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12609 on: March 08, 2016, 07:54:04 PM »
Itsu's ringing is primarily caused by the leakage inductance ...mostly.  Eliminate that with a proper winding and you will eliminate most of the ringing below 2*VCC.

Hi Verpies. What is the proper type of winding to reduce leakage inductance?

Offline verpies

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12610 on: March 08, 2016, 08:32:35 PM »
Hi Verpies. What is the proper type of winding to reduce leakage inductance?
Spanning the entire circumference of the toroidal core in even number of layers in forward&back circumferential directions. 
The same toroidal winding direction of all layers.

P.S.
There is also a way to do it in one layer, but it is difficult to describe it with words without drawing.  Anyway the name of the game is to span the entire circumference of the core and cancel any circumferential current.

Offline Void

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12611 on: March 08, 2016, 08:51:21 PM »
Spanning the entire circumference of the toroidal core in even number of layers in forward&back circumferential directions. 
The same toroidal winding direction of all layers.
P.S.
There is also a way to do it in one layer, but it is difficult to describe it with words without drawing.

Thanks Verpies. Just to be sure I understand correctly, do you mean that for the purposes of reducing
leakage inductance, it is always better to use the whole toroid for windings than to wind multiple layers
on just one side of a toroid for a particular winding? If it is a short winding, then we should just leave more
space between each turn to make use of the entire toroid circumference?

Offline itsu

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12612 on: March 08, 2016, 09:51:54 PM »
The drain to source capacitance is more that 2pF.  The additional inter-turn capacitance would make it even higher.
But it is not the ~60μH that is ringing with this capacitance.  It is the much smaller leakage inductance which forms an LC tank with this capacitance.  The leakage inductance should be measured with the secondaries shorted.

So with these numbers the LC resonance of the leakage inductance seems plausible.
Good. That confirms that the 14MHz ringing comes from the drain circuit.

However that does not explain the 35.25MHz peak and the 9.416MHz peak with its harmonics.
Please repeat this test with a 100pF capacitor and note whether these peaks are also affected.
This means that the magnet forces the alternating magnetic flux out of the core, because the core forms a circular magnetic path and affecting any part of it would affect the inductance of both windings equally.


I used a 100pF cap between drain and source while having 4 stacked magnets halfway this drains primary.

First sreenshot shows the peaks without the 100pF cap in place,
second screenshot is with the 100pF cap in place.

So the oscillations are being tempered/dampend by this cap.

An annoying fact is that during these oscillations, i frequently lose the mouse of my (3m away) PC, so making a screenshot is difficult and i need to unplug/replug the mouse USB plug to get it back.

Itsu

Offline Void

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12613 on: March 08, 2016, 10:27:04 PM »
An annoying fact is that during these oscillations, i frequently loss the mouse of my (3m away) PC, so making a screenshot is difficult and i need to unplug/replug the mouse USB plug to get it back.

Hi Itsu. I have seen a problem like that before as well with USB devices. A couple of
years ago I was testing some circuit setup, and every time I was set to some particular HF frequency
range it was making my mouse freeze up on my computer. Computer USB devices seem to be very sensitive to
EM radiation in certain HF frequency ranges. :)

Offline verpies

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Re: Kapanadze Cousin - DALLY FREE ENERGY
« Reply #12614 on: March 09, 2016, 12:29:27 AM »
I used a 100pF cap between drain and source while having 4 stacked magnets halfway this drains primary.
So the oscillations are being tempered/dampened by this cap.
It's my fault for being ambiguous.  I meant for this cap to be across the drain and the VCC of the primarys' windings center-tap.

An annoying fact is that during these oscillations, i frequently lose the mouse of my (3m away) PC, so making a screenshot is difficult and i need to unplug/replug the mouse USB plug to get it back.
Is the USB cable unshielded?