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Author Topic: Lenzless resonant transformer  (Read 99971 times)

Offline itsu

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Re: Lenzless resonant transformer
« Reply #45 on: February 20, 2014, 10:30:44 AM »
Test done by itsu, testing resonance effect in a toroid using two similar overlapped coils. Differs from my tests where coils were separate and on opposite sides of the toroid. But an interesting test result still.






Ok, i can now work on some suggested changes, like using prim./sec.  on opposite sides of the toroid.
But first i will try some more measurements suggested by verpies like testing resonance with secondary open or bulb only.
And to rewind my coil to be forth and back around the core instead of twice around it as it is now.

Regards Itsu



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Re: Lenzless resonant transformer
« Reply #45 on: February 20, 2014, 10:30:44 AM »

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Re: Lenzless resonant transformer
« Reply #46 on: February 20, 2014, 10:32:00 AM »
Test done by itsu, testing resonance effect in a toroid using two similar overlapped coils. Differs from my tests where coils were separate and on opposite sides of the toroid. But an interesting test result still.
Do you realize that by making the coils narrow and separate and winding them on opposite sides of the toroid you decrease the coefficient of magnetic coupling and increase flux leakage?  This significantly decreases the energy transfer efficiency in such transformer.

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Offline Jack Noskills

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Re: Lenzless resonant transformer
« Reply #47 on: February 20, 2014, 11:01:35 AM »
Magnetic current wants to loop back to itself through every possible route it can, even through air. Air has permeability of 1, my core has 80000. It is my opinion that this looping occurs according to path reluctance, so in my case only 1/80000 part would go through air so this leakage will be insignificant here.


But, purpose here is just to check how resonance effect changes by using two coils on opposite sides. I should have tested this myself but I forgot, so my bad. In my testing using two separate coils I had just one resonance point (primary lamp off while brightly secondary lit), but maybe my rude measurement style just did not notice it. My input bulb was 5 watt and output 10 watt halogen. Normal trafo operation would be that input bulb always has more light than output right ?


If I would use small capacitor in place of bulb then that should give me maximum input power system can use at a certain frequency ? How to compute that, Q*U*U*2*frequency ?

Offline itsu

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Re: Lenzless resonant transformer
« Reply #48 on: February 20, 2014, 12:43:20 PM »
My input bulb was 5 watt and output 10 watt halogen. Normal trafo operation would be that input bulb always has more light than output right ?

Well, remember that the input bulb is "outside" the primary (parallel) LC, while the output bulb is inside the (serial) LC, so i doubt
that "Normal trafo operation" applies on the brightness of these bulbs.

The second question i leave for more knowledeable people  :)

Regards Itsu


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Re: Lenzless resonant transformer
« Reply #49 on: February 20, 2014, 01:48:38 PM »
Magnetic current wants to loop back to itself through every possible route it can, even through air. Air has permeability of 1, my core has 80000.
That is almost true.  The cs.area and length of the magnetic path are also factors.

It is my opinion that this looping occurs according to path reluctance, so in my case only 1/80000 part would go through air so this leakage will be insignificant here.
80000 relative permeability is a lot for a ferrite core, but it is achievable with Metglas and Nanoperm materials.
However, 80000 relative permeability does not mean 80000 lower reluctance than air when core shape/length and its crossection are accounted for.
But, yes most of the flux will be confined to the core of such high permeability.

But, purpose here is just to check how resonance effect changes by using two coils on opposite sides.
Large current flowing in the secondary winding will expel flux from under it, even if the permeability of the core is 80000.
Sufficiently large secondary current will make that core segment appear as if it had the permeability close to air.
This effect is not minor like the previous one.

Also, when the high permeability core saturates at 1A and 100 turns, then its differential permeability will fall down to almost 1 and it will create a lot of transfer nonlinearities before that.

It makes no sense to invest in a core with 80000 permeability only to decrease the magnetic coupling coefficient of a transformer built upon this core by pri/sec winding separation.
If you want to have small magnetic coupling coefficient in a transformer, you might as well build it around a low permeability core or an air gapped core (both will not saturate so easily and will be more linear).

Normal trafo operation would be that input bulb always has more light than output bulb, right ?
No, because the input bulb indicates the input current and the output bulb indicates output power.

Well, remember that the input bulb is "outside" the primary (parallel) LC, while the output bulb is inside the (serial) LC, so i doubt that "Normal trafo operation" applies on the brightness of these bulbs.
That's true, too.

If I would use small capacitor in place of bulb ...
Which bulb?

Free Energy | searching for free energy and discussing free energy

Re: Lenzless resonant transformer
« Reply #49 on: February 20, 2014, 01:48:38 PM »
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Offline Jack Noskills

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Re: Lenzless resonant transformer
« Reply #50 on: February 20, 2014, 01:59:30 PM »
capacitor in place of input bulb

Offline Jack Noskills

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Re: Lenzless resonant transformer
« Reply #51 on: February 20, 2014, 03:09:57 PM »
If parallel capacitor in the primary side is removed so that only inductor is left, would bulb in primary side reflect power consumption any better ?

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Re: Lenzless resonant transformer
« Reply #51 on: February 20, 2014, 03:09:57 PM »
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Online verpies

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Re: Lenzless resonant transformer
« Reply #52 on: February 20, 2014, 03:40:37 PM »
If I would use small capacitor (C1) in place of the input bulb then that should give me maximum input power the system can use at a certain frequency ? How to compute that, Q*U*U*2*frequency ?
First calculate the total reactance of the primary circuit at given frequency XC1 + (1/XC2 + 1/XL).
The capacitive reactance is equal to XC=-1/2πfC
The inductive reactance is equal to XL=2πfL

Then use the MPTT to compute power in the primary circuit.

Finally you'll have to account for the reflected impedance of the secondary circuit, e.g. the real part of the secondary impedance (the ohmic resistance) will influence the inductance of the primary winding. The higher the mutual magnetic coupling and the lower the resistance of the secondary circuit, the lower the apparent inductance of the primary winding.  Calculating the reflected imaginary part of the secondary impedance, will put hair on your chest.

Offline itsu

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Re: Lenzless resonant transformer
« Reply #53 on: February 21, 2014, 12:22:24 AM »
First some open ends from yesterday answered:

(Mind you this is now with 7nF caps instead of the 220nF caps used in the video yesterday.
I redid the same test yesterday also with 7nF caps and the results where similar as with the 220nF caps in the video, only the resonance frequencies where higher).


opening the secondary and scoping the primary LC (while injecting a signal with an extra few (7) turns) shows a more peak like
resonance (using 7nF cap) of 21.3KHz at 80V pp, while the 40Vpp frequencies are at 44 and 11KHz.

Connecting my bulb to the secondary only, removes any resonance completely, at least i see no more resonance peak.


I then rewinded my coil to have 2 complete turns on the circumference of the core, but after 1 revolution i turned back, so have now
a forth and back kind of winding (this is where the next video starts).

I redid the above tests, pointing to a somewhat similar resonance peak of around 22KHz (7nF cap prim, open end sec), while when attaching the
bulb to the secondary again, the resonance disappears!


Then i set up again the first test with this rewounded coil, meaning primary LC (7nF cap) feeding through the input bulb, and output bulb inbetween the
secondary series LC.


Hunting for resonance now reveals a total different picture as yesterday, as the primary peaks (bulb off) around 22KHZ and the secondary
peaks (output bulb dimly on) around 550KHz!!??

Further measurements include the input power (SG rms voltage * SG rms current = Math avg) when primary in resonance and secondary in resonance.
It shows that the input current around primary resonance was leading or trailing the input voltage by 90° depending on which side of the resonance we are.
But it also shows that when the secondary is in resonance, the input voltage and current are in phase, meaning a pure resistive load?

Video here:  http://www.youtube.com/watch?v=o2HzTHopA_Y&feature=youtu.be   

Questions:
why is the resonance disappearing when connecting the bulb only to the secondary (load is to much)?
why is after rewinding the coil the both resonances way off (prim. res at 22KHz / sec res. at 550KHz)?


Regards Itsu
« Last Edit: February 21, 2014, 09:15:26 AM by itsu »

Offline Jack Noskills

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Re: Lenzless resonant transformer
« Reply #54 on: February 21, 2014, 09:18:22 AM »

You have confirmed the effect I had. I did not notice the first resonant point, most likely because it was below 1 kHz and I started sweeping from 1 kHz. Though this coil is still different from mine effect seems to be the same: second resonance point orders of magnitude higher than the first one.


What if you now remove the capacitor in primary and feed the system with 550 kHz, the second resonant frequency (could be that this changes when cap is removed) ? Primary should now effectively block all current flow and when bulb is connected to output then its effect on primary would be low.


Possibly more power now flowing on the output side compared to input side ?
Change to bigger capacitor in the output. Second resonance frequency would come down, does output power increase ?




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Re: Lenzless resonant transformer
« Reply #54 on: February 21, 2014, 09:18:22 AM »
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Online verpies

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Re: Lenzless resonant transformer
« Reply #55 on: February 21, 2014, 11:40:56 AM »
Opening the secondary and scoping the primary LC (while injecting a signal with an extra few (7) turns) shows a more peak like
resonance
Don't think that those 7 extra turns are loosely coupled.  They are not.
As such they will not allow the resonance amplitude to build up higher than SG's amplitude (measured on those extra turns) :(

Connecting my bulb to the secondary only, removes any resonance completely, at least i see no more resonance peak.
...
Q:Why is the resonance disappearing when connecting the bulb only to the secondary (load is to much)?
Due to the high magnetic coupling coefficient, connecting a bulb across the secondary is equivalent to connecting the same bulb across the primary (and leaving the secondary open).  You can try it and see the equivalence for yourself.  The resistance of this bulb significantly decreases the Q of the primary LC tank, decreases its amplitude and flattens its frequency response.

I then rewound my coil to have 2 complete turns on the circumference of the core, but after 1 revolution i turned back, so have now a forth and back kind of winding (this is where the next video starts).
By keeping the turn direction constant for 60 turns and reversing the circumferential advancement after 1 revolution and even number of revolutions (2), you have made a transformer that is close to an ideal.  It has almost not flux leakage, no leakage inductance and magnetic coupling coefficient close to 1.

That is very good for an IMT or a power supply transformer, but for the purpose of an oscillator it has no leakage inductance that could oscillate.

I redid the above tests, pointing to a somewhat similar resonance peak of around 22KHz (7nF cap prim, open end sec), while when attaching the bulb to the secondary again, the resonance disappears!
The same statement below is even more true because the coefficient of mutual coupling is even closer to 1 than before.

"Due to the high magnetic coupling coefficient, connecting a bulb across the secondary is equivalent to connecting the same bulb across the primary (and leaving the secondary open).  You can try it and see the equivalence for yourself.  The resistance of this bulb significantly decreases the Q of the primary LC tank, decreases its amplitude and flattens its frequency response."

Now the frequency response is so flattened that it appears to disappear.

Then i set up again the first test with this rewounded coil, meaning primary LC (7nF cap) feeding through the input bulb, and output bulb inbetween the secondary series LC.
Hunting for resonance now reveals a total different picture as yesterday, as the primary peaks (bulb off) around 22KHZ and the secondary peaks (output bulb dimly on) around 550KHz!!??
Q: Why is after rewinding the coil the both resonances way off (prim. res at 22KHz / sec res. at 550KHz)?
Again, that's due to the high magnetic coupling coefficient of an almost ideal transformer.  The free secondary inductance almost does not exist - it is converted to a voltage source by the transformer action.  Whatever remains resonates at 550kHz.  Also, all loads connected to the secondary are reflected into the primary almost without any losses.

It shows that the input current around primary resonance was leading or trailing the input voltage by 90° depending on which side of the resonance we are.
As it should, as it should

But it also shows that when the secondary is in resonance, the input voltage and current are in phase, meaning a pure resistive load?
Yes...or that any remainng inductive reactance has been cancelled by capacitive reactance (or vice versa).
It should be investigated

Video here:  http://www.youtube.com/watch?v=o2HzTHopA_Y&feature=youtu.be   
For OU hunting purposes the interesting situation would occur when the phase shift between the input voltage and current was 90º and on the output side - 0º.
« Last Edit: February 21, 2014, 02:32:27 PM by verpies »

Offline itsu

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Re: Lenzless resonant transformer
« Reply #56 on: February 21, 2014, 03:52:35 PM »

Thanks for this great info.


Quote
Don't think that those 7 extra turns are loosely coupled.  They are not.

Ok,  what i meant was, it was not directly coupled into one of the both coils dampening them by the 50 Ohm impedance of the SG.


Quote
By keeping the turn direction constant for 60 turns and reversing the circumferential advancement after 1 revolution and even number of revolutions (2), you have made a transformer that is close to an ideal.  It has almost not flux leakage, no leakage inductance and magnetic coupling coefficient close to 1.

That is very good for an IMT or a power supply transformer, but for the purpose of an oscillator it has no leakage inductance that could oscillate.

Ok,  so i will keep this ideal transformer for some project where i need an IMT.
A good Impedance Matching Transformer is hard to come by.

Quote
Yes...or that any remainng inductive reactance has been cancelled by capacitive reactance (or vice versa).
It should be investigated

Ok,  i will do some more testing when the secondary is in resonance around 550KHz like also mentioned by Jack above.


At the moment i am winding a new toriod consisting of 2x 200 turns (cw and ccw) of 0.4mm magnet wire on opposite sides of the core like Jack seems to have and do some similar tests.

I can say now already that it does NOT take just half an hour to make it like suggested by Jack earlier  :)

Regards Itsu


Online verpies

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Re: Lenzless resonant transformer
« Reply #57 on: February 21, 2014, 06:19:44 PM »
Ok,  what i meant was, it was not directly coupled into one of the both coils dampening them by the 50 Ohm impedance of the SG.
I estimate that the 50Ω of SG appears as ~300Ω to the primry LC tank after impedance reflection and magnetic coupling coefficient of these 7 turns slightly less than 1.

Ok,  so i will keep this ideal transformer for some project where i need an IMT.
A good Impedance Matching Transformer is hard to come by.
A 1:1 IMT is not very useful.  To make a 100:1 IMT you'll need to rewind :(
What is the core's material anyway?

At the moment i am winding a new toriod consisting of 2x 200 turns (cw and ccw) of 0.4mm magnet wire on opposite sides of the core like Jack seems to have and do some similar tests.
That will make Jack happy.
The leakage inductance of this transformer will be higher.  This leakage inductance will form an LC tank with a capacitor.
Note, that the same effect can be accomplished with an ideal transformer by connecting external inductors in series with its windings.

I can say now already that it does NOT take just half an hour to make it like suggested by Jack earlier  :)
Maybe he has a Jovil machine ;)
I hate winding toroids by hand - my spools are always too big to fit through the core's hole  >:(

Offline itsu

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Re: Lenzless resonant transformer
« Reply #58 on: February 21, 2014, 10:00:13 PM »


Quote
A 1:1 IMT is not very useful.  To make a 100:1 IMT you'll need to rewind :(
What is the core's material anyway?

Well, my plan was to put the both coils in series creating one primary using a new coil of a few turns as new secondary.

The core's material is unknown to me, but knowing the od (65mm), the id (40mm), the thickness (9mm) and the inductance with a 5 turns coil (20uH)
i calculate the permeability to be around 1000 using the methode given by Vasiliy Buslaev (where did he go?) here

Quote
Maybe he has a Jovil machine ;)
I hate winding toroids by hand - my spools are always too big to fit through the core's hole  >:(


It just fits  :)

Regards Itsu

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Online verpies

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Re: Lenzless resonant transformer
« Reply #59 on: February 22, 2014, 02:04:24 AM »
Well, my plan was to put the both coils in series creating one primary using a new coil of a few turns as new secondary.
I hate to split hairs but my transformers always work better when the secondary is under the primary winding (...or interleaved together).

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Re: Lenzless resonant transformer
« Reply #59 on: February 22, 2014, 02:04:24 AM »

 

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