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Author Topic: Rediscovering Zaev’s ferro-kessor  (Read 37017 times)
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Hi Vasik,

[snip]

As a side note, in the past while running experiments with certain powdered metal cores, I noticed this possible adiabatic demagnetization.  If a given coil/core was fed with a constant current 'x' for a period of time and then allowed to collapse, the energy was slightly greater than that measured from the same coil/core when ramped to the peak current level 'x' from a dc supply.  At the time I thot this was some kind of flux delay but now I wonder!?  I will revisit those tests.

Regards,
Pm

FWIW, here are some results of my earlier tests of profiling a T225-26B powdered iron core under the conditions I mentioned above.

200ma    delta = 1.11
300ma    delta = 1.13
400ma    delta = 1.15
....
1000ma  delta = 1.24

Regards,
Pm
   

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I'm wondering if copper and core mass differences would matter theoretically as your core/coil combo in your Meg2 pdf is considerably larger than my current test transformer?

Hi Partzman,

Yes, according to my understanding core volume is important here. Core is a "working body" in such setups where actual energy gain happens.

Regards,
-V.


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Not quite related maybe but I saw once a patent when similar computation was done and claiming it is useful efficient usage of energy. It was some quite old patent when the input was high frequency DC pulses of much higher voltage then normally applied for common electric appliances for 230V AC. It was like 320-400VDC in very sharp strange pulses - according to patent resulting in the sam energy conversion output (heat or light) with lower energy input.

I think application of short and very strong force (pulses in case of electronic setups) can be used to construct devices for extracting energy from all kinds different media. I think that this is a universal method. Reason why it works is that speed of media reaction on such "disturbance" is limited (depends on media) and we can use reaction of the media to perform useful work.



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Hi Vasik,

Update, I've been able to reach a COP = .963 with much fine tuning using an optimum load of 113 ohms with the 1/4" square core arrangement but don't seem to be able to reach any higher efficiency!

Regards,
Pm

So you got nice very efficient converter :) Now you can try optimize it even more.
Such high load resistor suggest that you have too big coil inductance. Perhaps you can try reduce number of turns e.g. by half.
Inductance will be smaller and so maximum power transfer point will occur with smaller load resistance.
Smaller resistance will allow you have longer transient time (so heat can perform more work)
and on the primary side you also will need shorter pulse.
Something like this :)








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FWIW, here are some results of my earlier tests of profiling a T225-26B powdered iron core under the conditions I mentioned above.

200ma    delta = 1.11
300ma    delta = 1.13
400ma    delta = 1.15
....
1000ma  delta = 1.24

Regards,
Pm

Powdered iron is very perspective material for experiments because it has much higher permeability (but I not sure about losses)...


Edit: PS If you have IR thermometer than you probably can see that core cools down in such mode (you need run it for a while to see the effect)
« Last Edit: 2017-11-22, 20:23:44 by Vasik041 »


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So you got nice very efficient converter :) Now you can try optimize it even more.
Such high load resistor suggest that you have too big coil inductance. Perhaps you can try reduce number of turns e.g. by half.
Inductance will be smaller and so maximum power transfer point will occur with smaller load resistance.
Smaller resistance will allow you have longer transient time (so heat can perform more work)
and on the primary side you also will need shorter pulse.
Something like this :)

Vasik,

OK, I have finally achieved a gain of ~1.03 by dropping the turns, using a complete E core, optimizing Rload, and increasing the supply to 60v dc to reduce the input pulse period that seems to improve the efficiency.  The energy is low level at ~10uJ but real and repeatable.  For maximum accuracy, I have to manually adjust the channel gains on the scope to utilize the full screen 8 bit resolution and for comparison I check against the hi-res mode which is 12 bits minimum but doesn't allow averaging.  They compare favorably.  I'm also using a Tek TCP0020 current probe with auto zeroing that has proven itself to be accurate at these frequencies.

This is still with a modified 1/4" square core so I will now try using a larger core to compare the results.

Regards,
Pm
   

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Vasik,

OK, I have finally achieved a gain of ~1.03 by dropping the turns, using a complete E core, optimizing Rload, and increasing the supply to 60v dc to reduce the input pulse period that seems to improve the efficiency.  The energy is low level at ~10uJ but real and repeatable.  For maximum accuracy, I have to manually adjust the channel gains on the scope to utilize the full screen 8 bit resolution and for comparison I check against the hi-res mode which is 12 bits minimum but doesn't allow averaging.  They compare favorably.  I'm also using a Tek TCP0020 current probe with auto zeroing that has proven itself to be accurate at these frequencies.

This is still with a modified 1/4" square core so I will now try using a larger core to compare the results.

Regards,
Pm

Hi Partzman,

Congratulations and thank you for doing this.
In my experiments E core with small gap in central leg and tiny magnets behaved better. I guess because gap is smaller and magnetic field of permanent magnet not "squeezed" outside. There is lots of improvements of possible but in general it works :)

Regards,
-V.

BTW have you tried reversing magnets polarity ? different magnets size ?



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Hi Partzman,

Congratulations and thank you for doing this.
In my experiments E core with small gap in central leg and tiny magnets behaved better. I guess because gap is smaller and magnetic field of permanent magnet not "squeezed" outside. There is lots of improvements of possible but in general it works :)

Regards,
-V.

BTW have you tried reversing magnets polarity ? different magnets size ?

Hi Vasik,

It's a pleasure to do the experiments! 

I will have to grind the center leg of the E core for the magnet placement and then lap for a good fit.  I also will try some other configurations I have used in the past such as placing the PMs
outside the core, etc.

Yes, I have tried reversing the magnetic polarity so that the primary bucks or aids the PM core flux if this is what you mean.  If you mean to change the bucking PM pole from north to south, no
I haven't tried this.

At this time I have a rather limited number of neo PM sizes but what I have I hope will be more favorable using larger core sizes.

I'm wondering if instead of using a resistive load for the output, what the results might be if a low voltage sink was used to extend the collapse time?  The output energy could be easily calculated
over the lengthened time period until the secondary current was fully depleted.  I will give this a try.

Regards,
Pm
   

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Hi Partzman,

You have nice attitude. Most people don't like doing experiments and demand ready solutions forgetting how long it takes sometimes from scientific discovery to real applications.

Yes, I have tried reversing the magnetic polarity so that the primary bucks or aids the PM core flux if this is what you mean.
Yes, that is what I mean.

Quote
If you mean to change the bucking PM pole from north to south, no I haven't tried this.
I think there is no difference. I haven't paid attention to this.

Quote
I'm wondering if instead of using a resistive load for the output, what the results might be if a low voltage sink was used to extend the collapse time?  The output energy could be easily calculated over the lengthened time period until the secondary current was fully depleted.  I will give this a try.
You can use electronic load, current sink. It allow you find MPTP easily but I don't think that it will extend collapse time.
May be I miss something ?

Regards,
-V.





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Dear Vasik,

i was looking at the meg2.pdf which can be found here: http://www.overunityresearch.com/index.php?topic=3453.msg61109#msg61109
and i found that the mentioned core (which is very hard to find if it exists at all) does not match the mentioned magnets.
The used core has a middle gap of 1mm wide (the G1000 part) but the magnets are 1.5mm thick, see below.
So something does not add up, any idea what? 

core E55/21 N27, B66335-G1000-X127                                  = 1mm gap
Q-05-04-1.5-N magnets inserted into core’s central leg gap     = 1.5mm wide magnets

Regards Itsu
   

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Dear Itsu,

I am attaching page from EPCOS catalog.
You can also see it online https://en.tdk.eu/download/519704/069c210d0363d7b4682d9ff22c2ba503/ferrites-and-accessories-db-130501.pdf (page 448).

E core consists of two parts. Each part has 1mm gap.
1+1 = 2 > 1.5
Does it add up now ?

Core bought on sale, it is obsolete. E27 is core material replaced by E87 and E97.

Yes, it is very hard to find :-/

https://www.ebay.com/sch/i.html?_odkw=B66335-G1000-X127&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xepcos+e+core+e55.TRS0&_nkw=epcos+e+core+e55&_sacat=0

Regards,
-V.


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Quote
1+1 = 2 > 1.5
Does it add up now ?

Almost, still having a 0.5mm difference, but i guess that is ok.  I thought the magnets should fit snuggly inbetween the gap.


Quote
Core bought on sale, it is obsolete. E27 is core material replaced by E87 and E97.

Yes, it is very hard to find :-/


Right, its replaced by N87 material now, guess that that also is of no concern then?
By the way, the ebay link only shows non-gapped cores.


Anyway, thanks for the comments, i will try to locate the correct, or close to, components.

A good source might be this one in the UK:  http://pacecomponents.worldsecuresystems.com/shop     thanks to Grumage


Regards Itsu 
   

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Almost, still having a 0.5mm difference, but i guess that is ok.  I thought the magnets should fit snuggly inbetween the gap.
Right, its replaced by N87 material now, guess that that also is of no concern then?
By the way, the ebay link only shows non-gapped cores.
Anyway, thanks for the comments, i will try to locate the correct, or close to, components.
A good source might be this one in the UK:  http://pacecomponents.worldsecuresystems.com/shop     thanks to Grumage
Regards Itsu

For experiments you can choose anything you have at hand. No need to search for exact same components.
I do not know if they are optimal. Most probably not.

Regards,
-V.



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Thanks -V,   i will try with what i have and see if i also can reach cop >1 with it.

Itsu
   
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Hi Vasik and Itsu,

Attached is a test with a core/pm arrangement that is at least easier for me to construct and tune using the same previously described circuitry.  The core is .25" (6.35mm) square, the end pole pieces are cut out of a donor core, and the pm's are N35.  The pm polarity is such that like poles face the center ferrite so the short legs of the E core are biased either in an aid or buck mode referenced to the coil flux.  The pm's can slide up and down on the ferrite pole pieces for fine tuning the ratio of core/pm saturation.  In this test case, the pm flux aids the coil flux.

I have found that by shortening the input pulse period by increasing the supply voltage while maintaining the same input current peak maximizes the efficiency.  This makes sense IMO if we are charging the coil by an adiabatic means.  The overall period between test sampling is 50ms.

The first scope pix shows the mean input current offset from the probe measurement, and is subtracted from the mean input current if necessary for measurement accuracy.  This is very important in the process of calculating the energy because if not done, you will be chasing your results all over the place.  The scope traces are averaged over 32 cycles minimum.

The second scope pix shows the input measurements and the third pix is the output measurement.  Note that the input current is measured in mean and the output volts in rms.

The load for this test is 65.5 ohms and the coil is 146 turns.  The core is Magnetics "P" material with an initial permeability of ~2500 at 25 degrees C.

The calculated input energy is 7.34 x 3.06e-6 = 22.46uJ and the output energy is 2.121^2/65.5 x 334e-6 = 22.94uJ.  The apparent COP = 22.94/22.46 = 1.0214.

Regards,
Pm

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Hi Partzman,

Interesting core arrangement, I haven't tried it like this :)
The issue with such setups is that mu of magnet is almost 1 (like an air gap).
But in order to increase useful energy we need reduce it so we get more energy in core and coils.

Losses in coil can be calculated as I^2 R t, so decreasing pulse time you can decrease losses at the same time rising voltage proportionally to achieve same peak current.

Regards,
-V.



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Hi Partzman,

Interesting core arrangement, I haven't tried it like this :)
The issue with such setups is that mu of magnet is almost 1 (like an air gap).
But in order to increase useful energy we need reduce it so we get more energy in core and coils.

Thanks for the comment!  Yes I understand the mu of the PM but I don't understand what you mean exactly by needing to reduce it, or do you mean to reduce the effects of the low mu on the overall circuit operation?

Quote
Losses in coil can be calculated as I^2 R t, so decreasing pulse time you can decrease losses at the same time rising voltage proportionally to achieve same peak current.

Regards,
-V.

Again I agree, so I re-ran the test with a 60v dc supply to compare the losses in the primary to see if the gain is due to decreased loss in the coil or possibly due to adiabatic charging of the coil.  When keeping the peak input current the same as well as the load used in the 120v dc test, the COP = .9355 with a 60v dc supply.  The dcr of the 146 turn coil is .67 ohms.

In the test posted earlier, the input mean current is 61.05ma for a period of 3.06us resulting in a loss of 8nJ.

Using a 60v dc supply with all else kept the same except the input period, the input mean current is 65.3ma for a period of 6.524us resulting in a loss of 19nJ.  The current measurements in this case should be in rms so we should apply a correction factor but I think as we shall see, the results would be insignificant either way.

So, the gain resulting from the decrease in I^2 R t at 120v dc is ~11nJ.  This is ~.05% of the average input energy.  The gain in COP however is ~(1.02-.94)/.94 = 8.5%.  It would appear the gain increase is coming from some source other than just the decrease in coil loss.

Regards,
Pm     
   

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Thanks for the comment!  Yes I understand the mu of the PM but I don't understand what you mean exactly by needing to reduce it, or do you mean to reduce the effects of the low mu on the overall circuit operation?
Sorry for being unclear. I mean reduce gap occupied with magnets or height of magnets.

See for example this http://www.vias.org/matsch_capmag/matsch_caps_magnetics_chap3_17.html
"Although the air gap has a volume of only 1.1 percent that of the iron, it stores 24.4 times the energy stored in the iron."

Using electric circuit analogy you can think of magnet as current source with high internal resistance and ferrite core like a short circuit for it.

Quote
It would appear the gain increase is coming from some source other than just the decrease in coil loss.
Yes you right. There are two components here. One is losses on coil resistance and other is that making driver pulse shorter we increase ratio
between output and input pulse time. The more this ratio is the more FE we get.

Regards,
-V.





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Sorry for being unclear. I mean reduce gap occupied with magnets or height of magnets.

See for example this http://www.vias.org/matsch_capmag/matsch_caps_magnetics_chap3_17.html
"Although the air gap has a volume of only 1.1 percent that of the iron, it stores 24.4 times the energy stored in the iron."

Using electric circuit analogy you can think of magnet as current source with high internal resistance and ferrite core like a short circuit for it.

Hi Vasik,

OK, I understand now and thanks for the informative link above.

Regards,
Pm
   

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Still waiting for some ordered cores, but meanwhile i was trying to capture the BH curve of an ungapped E-core setup i have.
Both coils are 120 turns of 0.4mm² magnet wire, see picture.

The BH curve is shown in screenshot below.

The idea is to produce an identical BH curve with some gapped E-cores, and then try to manipulate with some magnets in the gap this curve
so it shows the looped curve which is responsable for the extra energy.

Would this be a sensible approach?

Itsu
   

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Hi Itsu,

I not sure what you mean "looped curve" but
in standard situation curve traversed anti-clockwise and area inside the curve corresponds to energy loss.
To achieve energy gain you need traverse curve clockwise.
This can be achieved by inserting magnet and asymmetric pulses (short in, long out).

Regards,
-V.

PS I am attaching Cyril's paper where he explains energy gain/loss. Please read only first 4 pages :)


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Vasic,

with "looped curve" i was pointing to the reversed part of the BH curve as mentioned and showed in the h2e.pdf

Itsu
   

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Vasik,
with "looped curve" i was pointing to the reversed part of the BH curve as mentioned and showed in the h2e.pdf
Itsu

Ok, I see.
In this setup for best performance you need find such magnet/core gap which bias core approximately to half of saturation.

Regards,
-V.


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Here the same setup, but now using a similar, but gapped, E-core (4mm gap). I have used the same coils as on the non-gapped E-core above.
This setup is based on the setup used by JL Naudin for his 2SGen tests:  http://jnaudin.free.fr/2SGen/indexen.htm   (2SGen Episode 10:)

Will be manipulating the gap with some magnets, not sure how to find out if the core is half saturated.

Thanks,   regards Itsu

   
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Here the same setup, but now using a similar, but gapped, E-core (4mm gap). I have used the same coils as on the non-gapped E-core above.
This setup is based on the setup used by JL Naudin for his 2SGen tests:  http://jnaudin.free.fr/2SGen/indexen.htm   (2SGen Episode 10:)

Will be manipulating the gap with some magnets, not sure how to find out if the core is half saturated.

Thanks,   regards Itsu

Itsu,

I'm sure Vasik will have more to add to this but IMO you could use the formulae found at this link-

https://www.supermagnete.de/eng/faq/How-do-you-calculate-the-magnetic-flux-density

to calculate the PM requirements based on Br, size and shape, gap, etc, compared to the Bsat of your core material.

In my test set, the overall flux density of the Pm is close to the Bsat of the material so this is not ideal.

Regards,
Pm
   
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