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Author Topic: Naudin's Gegene  (Read 214578 times)
Group: Guest
Further more....

I think this argument of resonance should be in moved to a new thread under the 'learning' section of the forum. It is obvious that use of the word 'resonant' in a description does not imply resonance to some and the many definitions posted are in conflict.

The original meaning had only to do with sound and means 'to resound'. So, any mechanical or electrical response to any form of strike or signal is resonance, be it half a cycle or long duration ringing.

tinman,

I would normally explain your scope shots, as requested but, any explanation offered would be met with a 'resounding' flurry of post bombing. Perhaps, I'll PM those to you.
   
Group: Guest
Further more....

I think this argument of resonance should be in moved to a new thread under the 'learning' section of the forum. It is obvious that use of the word 'resonant' in a description does not imply resonance to some and the many definitions posted are in conflict.

The original meaning had only to do with sound and means 'to resound'. So, any mechanical or electrical response to any form of strike or signal is resonance, be it half a cycle or long duration ringing.

tinman,

I would normally explain your scope shots, as requested but, any explanation offered would be met with a 'resounding' flurry of post bombing. Perhaps, I'll PM those to you.

That would be great WW.
Also guy's,im looking at getting a new scope-and would like your opinions on this one
http://www.triosmartcal.com.au/2195-siglent-digital-storage-oscilloscope-100-mhz-bandwith-2-channel.html

Cheers
   
Group: Guest
That would be great WW.
Also guy's,im looking at getting a new scope-and would like your opinions on this one
http://www.triosmartcal.com.au/2195-siglent-digital-storage-oscilloscope-100-mhz-bandwith-2-channel.html

Cheers

I'm not familiar with the brand but the price seems very good for the features. It looks like it would be a great scope to add to any experimenter's bench.
   
Group: Guest
Why are we saying that Q=1 is not resonant when Q<1/2 equals overdamped,
...

In this thread, the question is:

"Is resonance the cause of the functioning? Is it a primary and needed mechanism for the gegene?"
The answer is negative.

Here is an image. It's not because a wire has a resistance, that you would say that a LC oscillator works thanks to the resistance of the wire of the coil, isn't it?
If someone said it to you, I suppose that you would answer that this resistance is to be counted for zero, it has no role for the oscillation. And if your contradictor insisted by affirming that you are wrong because there is indeed a resistance and the resistance is > 0, what would you think of him? That he doesn't understand the functioning and he has no idea about the order of magnitude of electronics values involved in the circuit, that he is inexperienced and his remark is not relevant.

It's what happens to me when I hear EM speaking of resonance. Although we can define a Q, a so low value is not significant for the functioning. What we observe is the functionning of an ordinary transformer whose the primary is powered by switching transistors. This kind of setup is widely used in most of the switching power supplies. There is no resonance in the sense of a significant Q necessary for the functioning (a resonance would even be a nuisance by limiting the passband and preventing the transistor from high speed switching).


   
Group: Guest
In this thread, the question is:

"Is resonance the cause of the functioning? Is it a primary and needed mechanism for the gegene?"
The answer is negative.

The correct answer is 'positive'.

The resonance of the circuit is essential for control of energy applied to the load. Not only is the amplitude of the exciter signal controlled for this purpose but also the frequency and possibly the duty cycle.

As you can see in the scope shots, the exciter frequency is less than the resonant frequency. Should the experimenter decrease the output settings of the cooker the amplitude and frequency of the excitation signal will decrease. As most of us know from Tesla coils and basic electronics, the mutual inductance and therefore energy transfer improves between primary and secondary as the resonant point of each approach the same frequency.

Avoid the argument where the resistive load on the secondary appears in the primary. This is correct but do not forget that the reactivity of the primary is also shared with the secondary.

Yes, the resistance has the greatest affect upon the Q but remember that the primary IS a series LC circuit in either part of the switch cycle. The fact that the added secondary is coupled as a transformer secondary does not make the LC circuit and resistive load parallel. It means the total impedance of the secondary is reflected in the primary which includes the effects of the reactive values of the primary 180 deg out of phase. This is why only the resistive effects are measurable in the primary.

>>Note: the quality of primary to secondary coupling is never perfect and has an effect upon the reactive/non-reactive effects shared between windings. What is actually shared between coils is impedance not resistance. This cancellation (180 deg) of reactive properties is never 100%. So, the loose coupling between primary and pot seen is likely a designed in factor to allow resonance of the primary to exist well enough for control of energy applied to the pot.<< 

Any current increase in the primary is manifested in the secondary as a voltage increase - basic Faraday induction. This is displayed on tinman's scope because he uses a magnetic loop as a scope pickup.

In such a circuit decreasing the primary effective resistance increases the Q of the primary because the primary current increases and a current increase in a series RLC means either the load has increased due to lower load impedance or the exciter frequency approaches the resonant frequency of RLC which result in more energy applied to the load.

R=0 in this system means Qpri=Max not Qpri=Min.
« Last Edit: 2013-04-14, 22:06:08 by WaveWatcher »
   
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exnihiloest
Quote
The working frequency is the consequence of the time delay of the positive feedback. This doesn't imply resonance! Even a RC circuit can make transistors to oscillate.

Ok, now you're talking about the drive signal, so if you want to understand, continue analyzing what happens to this drive signal.    This signal is generated by the cooker and applied to the IGBT switches in the resonant converter to switch them ON and OFF.    The frequency is chosen by design to drive the primary coil inductance, and the associated capacitors, at their RESONANT frequency!  That's why its called a "resonant" converter!     And that's why there is resonance to speak of.  

Resonant converters are great circuits and quite practical and useful.  I suggest you take some time to study them, before posting nonsense.


WW,
let's tag team WW, your turn to wrestle  :D

tinman,
that's a great looking scope, at a great price, I like it!   I bought one a while ago that was about the same cost but only 25 MHz, but I returned it, glad I did, cause I might buy this model.
   
Group: Guest
I have read many reviews on the scope I posted, and all are good.
It seems to be one of the best in that price range.
   
Group: Guest
The correct answer is 'positive'.

The resonance of the circuit is essential for control of energy applied to the load.

The resonance of the circuit is not essential for control of energy applied to the load.

Quote
Not only is the amplitude of the exciter signal controlled for this purpose but also the frequency and possibly the duty cycle.

Non sequitur


Quote
As you can see in the scope shots, the exciter frequency is less than the resonant frequency.
...

As you can see in the scope shots, the exciter frequency is around 20 Khz and there is no resonant frequency (square signal and no overvoltage).

   
Group: Guest
...
The frequency is chosen by design to drive the primary coil inductance, and the associated capacitors, at their RESONANT frequency!
....

The frequency is not choosen, it is the result of the time constant of the positive feedback which depends on the IGBT and coil capacitances. A time constant doesn't imply a resonance.

   
Group: Guest
WW,
let's tag team WW, your turn to wrestle  :D

EM,

No thanks.

Weekdays don't leave me enough time to provide free tutoring.

He can't see the voltage increase in the non-squared portion of the waveform (half-wave resonant inverter) and doesn't believe the information written by the design engineers. You can lead a horse to water but you can't make them drink.

The only remaining problem here is that any further discussion using the word 'resonance' will be the end of the discussion as he takes up network bandwidth.

   
Group: Guest
Ok guy's-If i disasemble the cooker and place the prob only on the coil(as both the cooker and scope have a common ground,and i also have RCD's in the workshop)Would this show us what we need to see?.Everything i read says that these cooktops use a resonant converter.There is also a clear indication that resonance has many different shapes and form's in todays electronic's.

So in the name of reserch,im off to disasemble the new cooktop.If anyone has anything they would like me to try while i have the cooktop appart-just let me know here.Also,is there one partiqular place other than the coil that i should hook the scope probe to?Im getting a new scope shortly,so it's all out war on this one.
   
Group: Guest
...
There is also a clear indication that resonance has many different shapes
...

Resonance is mainly a sine signal because a resonance is at only one frequency, only one frequency is a narrow spectrum and a narrow spectrum implies a sine signal, consequence of the Fourier transform.
If you don't observe a sine shape, you may forget resonance.

   

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Quote from: exnihiloest
Resonance is mainly a sine signal because a resonance is at only one frequency, only one frequency is a narrow spectrum and a narrow spectrum implies a sine signal, consequence of the Fourier transform.
If you don't observe a sine shape, you may forget resonance.

The waveshape across the resonant components can
be of high spectral purity if the circuit is only very
lightly loaded.

In the case of industrial applications, the resonant
components are typically very heavily loaded so the
resultant waveshape is heavily damped.  A damped
oscillation is by its very nature not a pure sinusoid
as the loading induced distortion produces harmonics
and modulation products.

In high power industrial applications this distortion
is quite tolerable.

In the single ended Induction Cooker waveshape the
driven half cycle of resonance is significantly larger
than the free-wheeling circulating current half cycle
due to energy transfer to the load.  Since the oscillation
is reinforced each cycle by the driver circuit the desired
resonance is sustained even though the resultant
waveshape is lop-sided.  The conditions of resonance
are met.  DC input pulses result in an alternating current
within the resonant components.

Conversion is accomplished.

It may be instructive to monitor the output waveshape
of the Induction Cooker while it is "ON" but not yet loaded
by any metallic surface in proximity to the output coil.

Once "loading" is detected by the Control Circuits then
the Cooker will shift to normal high power output.

Ex's understanding of "resonance" seems to be predominantly
theoretical and he may lack actual experience with the plethora
of resonant circuits in common usage in other than Radio
Frequency Communications devices.


---------------------------
For there is nothing hidden that will not be disclosed, and nothing concealed that will not be known or brought out into the open.
   
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I have a test for the  cooktop, I'd like to see how long it takes to cook a nice porter house steak [seasoned with some Onions ,maybe a little celery ]
I like it a little rare in the middle?

 ?
atleast before yah break it.....

thx
Chet
   
Group: Guest
The waveshape across the resonant components can
be of high spectral purity if the circuit is only very
lightly loaded.

It may be instructive to monitor the output waveshape
of the Induction Cooker while it is "ON" but not yet loaded
by any metallic surface in proximity to the output coil.

Once "loading" is detected by the Control Circuits then
the Cooker will shift to normal high power output.


I actualy done this in the next video i will be posting within about an hour(waiting for conversion and upload to youtube)
Unloaded we see the half wave ac with a flat top,but when loaded we see something very different-looks like a full offset signwave with a half wave inbetween.This is at the 100Hz half wave cycle(50Hz rectified ac)
The probe is hooked to the active side of the coil.The scematic i posted is not the one for this cooktop,as this one only has 1 IGBT and two inductors(or what i believe to be inductors.
   
Group: Guest
I have a test for the  cooktop, I'd like to see how long it takes to cook a nice porter house steak [seasoned with some Onions ,maybe a little celery ]
I like it a little rare in the middle?

 ?
atleast before yah break it.....

thx
Chet
Funny you should say that Chet,as i tried that experiment last night-but it was a T bone and tomato.8 minutes,and it was cooked to perfection.My wife also done boiled eggs-4 minutes from cold water to hard boiled--much quicker than the gas stove.I now have a reprieve for spending the cash on an experiment lol.
   
Group: Guest
Here is the video of the internals of the induction cooktop i have.
http://www.youtube.com/watch?v=iubthURPRqw
   
Group: Guest
Here is the scope shots with the probe hooked directly to the induction cooktop coil-with and without a load.
http://www.youtube.com/watch?v=N2-T1PzOgEo
   
Group: Guest
...
In the case of industrial applications, the resonant components are typically very heavily loaded so the resultant waveshape is heavily damped.
...

I agree. The load delete more or less the resonance, the heavier load the lower the Q, heavier meaning damping. When the amplitude of the resonant frequency is not clearly distinguishable among the other components of the spectrum, the resonance has became not significant.

   

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Posts: 3217
It's not as complicated as it may seem...
Ex,

For argument sake, I think in electrical terms, resonance occurs any time there is an exchange or shuttling of energy between a capacitive and inductive reactance. This holds true even if this exchange is only half completed (say from L to C). No matter the Q (usually resistance of L), there is still "resonance".


---------------------------
"Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa
   
Group: Guest
Ex,

For argument sake, I think in electrical terms, resonance occurs any time there is an exchange or shuttling of energy between a capacitive and inductive reactance. This holds true even if this exchange is only half completed (say from L to C). No matter the Q (usually resistance of L), there is still "resonance".

I agree but...
Resonance being energy accumulated from period to period and stored in a system, each time there is energy temporarily stored in a component, we could speak of "resonance". But even if we accept this simplistic hypothesis which is equivalent to see resonance everywhere because a capacitor voltage or a coil current is stored energy, is it relevant when Q is low? Certainly not. When Q is low we can neglect the resonance, as well as we often neglect the resistance of wires connecting our components:
The experimenters of the gegene who don't observe overunity, say that the output voltage is of the same order as the primary voltage, due to a turns ratio near one. The provided primary energy is constantly dissipated by the load connected to the secundary coil. So where is the  energy stored by the alleged resonant effect? Even if it was only equal to the output energy, which would be a very low resonance, we would see somewhere in the circuit overvoltage or overcurrent coming from the stored energy and adding to the provided and used energy. But we see none. This means that the energy in each period is used by the load at each period. A not measurable accumulation means that the Q is very low, and consequently we dont need to invoke a resonance to explain the functioning.

The gegene is strictly identical to a switched-mode power supply whose the mains input is rectified but not filtered and the output is directly used without rectification.
You may verify at http://en.wikipedia.org/wiki/Switched-mode_power_supply that the principle of switching a voltage doesn't imply resonance, therefore speaking of resonance is irrelevant for the gegene.

Switched-mode power supply:


Gegene switched-mode power supply:


   
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It's a resonant converter topology, not a switch mode.

This is a good paper on resonant converters:

http://scholar.lib.vt.edu/theses/available/etd-09152003-180228/unrestricted/Ch4.pdf


Most CFL light bulbs use the same half bridge resonant converter topology, a good circuit for projects.
   
Group: Guest
It's a resonant converter topology, not a switch mode.

This is a good paper on resonant converters:

http://scholar.lib.vt.edu/theses/available/etd-09152003-180228/unrestricted/Ch4.pdf


Most CFL light bulbs use the same half bridge resonant converter topology, a good circuit for projects.

EM,

Friend to friend....

I'm worried about bruises forming on your forehead or even worse - brain trauma. Their is enough evidence of that here already  >:-)
   
Group: Guest
It's a resonant converter topology, not a switch mode.

This is a good paper on resonant converters:

http://scholar.lib.vt.edu/theses/available/etd-09152003-180228/unrestricted/Ch4.pdf
...

It's terrible that you use the pretext of LC circuits implemented for low cost reasons for the positive feedback at the input of the IGBTs (because a stable frequency is not required), to pretend that the resonance is a key feature of an induction cooker circuit, while there is no resonance at the output because of the switching operation and while the state of the art allows also to use PWM circuits to control the power stage, without any need of resonance!    C.C



It's like to say in the 1950's that the vacuum is needed for a radio receiver to work, because you would have seen that radio receivers use vacuum tubes!
It's the principle that one has to understand here: a simple switching of the mains frequency after rectification.

   
Group: Guest
while the state of the art allows also to use PWM circuits to control the power stage, without any need of resonance!    C.C

The current state of the art is to use resonant converters. Simple PWM control of energy applied to a pot was state of the art well prior to the 1980's.
The reasons provided in all papers I've read on the subject is because resonant converters offer higher efficiency of energy transfer to the pot than simple PWM devices.

Since when does an LC circuit become classified as not resonant simply because it is fed by a switching device?

This would mean the RF PA stage on my transceiver is not resonant? If this is thought then the poster should leave the thread in shame.
Perhaps, this argument is due to the energy being switched is a pulse? Not so shameful as many don't understand the differences between a planar and solenoid coil.
 
   
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