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Author Topic: Parametric Charging  (Read 36861 times)
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ooops, lost another ixdd614, 1.7Mhz @ 30V with heatsink is still to much after some time.

Trying to get the "vertical offset" to work, but it does not seem to function in the mean value box nor the math
function picks it up (the signal trace does go up or down with the offset value).

Where is my scope manual?


Itsu

Itsu,

IIRC, adjusting the channel offset will not affect the Math calcs.

Pm
   
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Itsu and all,

Here is a variation of the PSR that places the mosfets back-to-back, removes the schottky rectifier, and still retains the series load as seen in the schematic attached below.  Ch3(pnk) shows the resonance waveform after L1 for reference.

In the scope shot we see the offset current of 22.52ua is on the high side so we will ignore.  Pout = 42.72^2/14.81e3 = 123.2mw.  With pin = 15.9mw, the apparent COP = 123.2/15.9 = 7.75.

Regards,
Pm



   

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Itsu and all,

Here is a variation of the PSR that places the mosfets back-to-back, removes the schottky rectifier, and still retains the series load as seen in the schematic attached below.  Ch3(pnk) shows the resonance waveform after L1 for reference.

In the scope shot we see the offset current of 22.52ua is on the high side so we will ignore.  Pout = 42.72^2/14.81e3 = 123.2mw.  With pin = 15.9mw, the apparent COP = 123.2/15.9 = 7.75.

Regards,
Pm
Damn!
   
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Itsu and all,

Here is a variation of the PSR that places the mosfets back-to-back, removes the schottky rectifier, and still retains the series load as seen in the schematic attached below.  Ch3(pnk) shows the resonance waveform after L1 for reference.

In the scope shot we see the offset current of 22.52ua is on the high side so we will ignore.  Pout = 42.72^2/14.81e3 = 123.2mw.  With pin = 15.9mw, the apparent COP = 123.2/15.9 = 7.75.

Regards,
Pm

That is a remarkable COP - how confident are you? 
Would you say that this is your best design so far (despite the high freq)?
Also, what is the purpose of the variable pwr supply connected to R2?

Thank you for sharing as you proceed - and more power to you!
   

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Itsu and all,

Here is a variation of the PSR that places the mosfets back-to-back, removes the schottky rectifier, and still retains the series load as seen in the schematic attached below.  Ch3(pnk) shows the resonance waveform after L1 for reference.

In the scope shot we see the offset current of 22.52ua is on the high side so we will ignore.  Pout = 42.72^2/14.81e3 = 123.2mw.  With pin = 15.9mw, the apparent COP = 123.2/15.9 = 7.75.

Regards,
Pm


Hmmm,  "when it sounds too good to be true, it probably is" is the saying  i believe  :).

Calculating the real current by 0.1773V / 14810 Ohm = 11.97uA (scope measures 22.52uA, so almost double).
This means the the real input power is about 50% less then the calculated 15.9mW meaning about 8mW.

Holding this input against the calculated output of  42.72^2/14.81e3 = 123.2mw means a COP of 15.4, Right?  :D

If so, then its too good to be true in my opinion.

Do i understand it OK, that you are not using the correction PS at the csr?
Concerning this correction PS, could you clarify what it should do / does and what it consists of?
 
Will try to replicate tonight.

Itsu
« Last Edit: 2018-10-12, 13:54:07 by Itsu »
   
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That is a remarkable COP - how confident are you? 
Would you say that this is your best design so far (despite the high freq)?
Also, what is the purpose of the variable pwr supply connected to R2?

Thank you for sharing as you proceed - and more power to you!

I hope today to run some tests that will raise the confidence level (my own included) of these recent tests.  They are what they are and I certainly welcome any critical input as it is easy to overlook something.

This design is possibly the best as far as utilizing the parametric capacitance change in a mosfet but I'm thinking that it may go deeper than that.  What we have is a very low Q series resonant circuit due to a relatively large value load resistance operating with a large amount of harmonics.  Within the capacitance of this resonant circuit, we have diode decoupling at the zero current crossover point that in itself adds non-linearity and IMO has the effect of de-stabilizing the resonance effect.  With tests today, I hope to find out if substituting the mosfets with regular caps produces similar results due to the reasoning in my previous statement.

The purpose of the power supply connected to R2 which is connected to the high side of the CSR, is to allow cancellation of the offset voltage in the scope's input amplifiers.  These circuits in general at this time are operating at such low current levels that this offset becomes a major factor affecting the accuracy of the math measurements.  This could also be accomplished with a pot connected between a + and - supply with the wiper connected to R2 which basically allows us to supply a small amount of current to the CSR creating the required voltage offset change.

Pm
   
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Hmmm,  "when it sounds too good to be true, it probably is" is the saying  i believe  :).

Yes, and that saying may very well apply here.  Further testing will hopefully tell us what we need to know.

Quote
Calculating the real current by 0.1773V / 14810 Ohm = 11.97uA (scope measures 22.52uA, so almost double).
This means the the real input power is about 50% less then the calculated 15.9mW meaning about 8mW.

Holding this input against the calculated output of  42.72^2/14.81e3 = 123.2mw means a COP of 15.4, Right?  :D

If so, then its too good to be true in my opinion.

In this case and with this circuit, the offset voltage/current is not as critical as in the previous high ratio reactive/real circuits.  The change in the micro amps of offset will not materially affect the Math calculations as they previously did because of the relatively small phase angle between the driving pulse and the circuit current.  So, for this reason I just neglected the small offset however, I could be wrong in this regard.

IMO, mathematically correcting the offset as you suggested would not affect the COP.

Quote
Do i understand it OK, that you are not using the correction PS at the csr?

In the last posted scope pix no, I did not have the power supply turned on for any correction. 

Quote
Concerning this correction PS, could you clarify what it should do / does and what it consists of?

My previous explanation was not the best so we'll see if I can get it right this time.  I use a single variable supply that I adjust to provide the proper voltage level to create a current in R2 that is fed to the CSR to correct the "mean" current/voltage in the scope's current channel and therefore correct the scope's offset voltage.  The magnitude of the "mean" current is dictated by the circuitry and could be zero or any other level.  I change the polarity by simply flipping the leads to the supply.

A far better method would be to use a pot like I described to PhysicsProf.

Actually, the load could be used as the CSR in this case as this is the singular path for the current.  However, this will require a simple formula to be written in the scope's math channel calculator which I know the TDS series does not have this capability.  I am not sure about the Rigol's.

Quote

Will try to replicate tonight.

Great and good luck.   O0

Pm

Quote

Itsu
   
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All,

Here is a re-run of the previous "E" version test with the high COP showing two methods of calculating the pin.  It should be noted that I have two pairs of RFP14N05L's paralleled for this and the previous test.

The first scope pix is using the same measurement across the CSR as in the previous test using CH1 * CH4 which shows the pin = 14.47mw.  Pout = 40.68^2/14810 = 111.74mw for an apparent COP = 111.74/14.47 = 7.58.

The second scope pix uses the math formula pout = (CH2/Var1) * CH1 with  Var1 = 14.81k.  IOW, this uses the entire load resistance as the sense resistor and as can be seen, the pin = 14.76mw for an apparent COP = 111.74/14.76 = 7.57.

I would point out the horizontal resolution is at 1M points and the measurements are taken over 32 averaged samples.  Also, varying the mean current in the first version by 10's of microvolts has seemingly little to no effect on the pin.

Regards,
Pm

   

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OK, using your setup as in Post #351 with: 1mH air coil as L1, 14930 Ohm Rload (R3) and 10 Ohm csr at 40V.
No extra power supply at the csr.

I now see a big phase difference when using the current probe in its old position (before L1) or its new
position (between R3 and csr).
It causes the power input to change from 135mW to 6mW or so.

Probes (colors) are similar as in your drawing.

Strange is that the blue probe mean voltage is negative (mean voltage across R3).
So i cannot correct the current to its real value (i = -0.583 / 14930 = -39uA)
 
Input power calculated is 6.214mW
Power output is 39.12² / 14930 = 102.5mW

Using the current probe in the new position.

Not sure whats wrong with this.

By the way, i am onto my last IXDN614PI as the new batch IXDD614PI's i got from China have a problem as i already
blew up 3 of them.
looks like the are internally other/wrong connected as the old IXDN614PI i now got in works fine.

It seems these new IXDD614PI's i got cannot withstand any Vcc above 27V or so.
As the spec's say they could be used up to 40V Vcc (which we did without problems with the old ones), i guess
these are inferior parts from a 3th party manufacturer.

I have notified the seller about this.


Itsu
« Last Edit: 2018-10-15, 09:39:14 by Itsu »
   
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All,

The Mystery is solved and unfortunately there is no OU in the "E" series circuitry.  I found it odd that by adding more mosfets in parallel, the capacitance increased but the resonant frequency did not.  With the high load resistance, the current took the path of least resistance which happens to be the scope probe capacitance and the parasitic capacitance between components and ground.  It is the energy of the parasitic current that is not being accounted for on the low side current measurements.  The proof of this is when a current probe is used to measure the current from the pulse source and the Math channel uses this in the pin calcs, the COP <1.

So, I will continue to search for any gains using the mosfets but at this time, things look somewhat discouraging.

Regards,
Pm
   
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OK, using your setup as in Post #351 with: 1mH air coil as L1, 14930 Ohm Rload (R3) and 10 Ohm csr at 40V.
No extra power supply at the csr.

I now see a big phase difference when using the current probe in its old position (before L1) or its new
position (between R3 and csr).
It causes the power input to change from 135mW to 6mW or so.

Probes (colors) are similar as in your drawing.

Strange is that the blue probe mean voltage is negative (mean voltage across R3).
So i cannot correct the current to its real value (i = -0.583 / 14930 = -39uA)
 
Input power calculated is 6.214mW
Power output is 39.12² / 14930 = 102.5mW

Using the current probe in the new position.

Not sure whats wrong with this.

By the way, i am onto my last IXDN614PI as the new batch IXDD614PI's i got from China have a problem as i already
blew up 3 of them.
looks like the are internally other/wrong connected as the old IXDN614PI i now got in works fine.


Itsu

Itsu,

Thanks for your efforts in this replication!  I was creating my post during the time you posted so we crossed each other but basically your measurement with the current probe at the very front is the correct one for the reason stated in my last post. 

At this frequency, the parasitic capacitance paths can obviously greatly affect the measurements.  I should have checked for this before posting that version so to you and all the others here, I apologize. :-[

Regards,
Pm
   

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Partzman,

thanks for the info and no apologies needed, its all in this game.
I learned again a lot, so anytime you have something special, please put it out there for us replicators
to follow up.

Already looking forward to the next one  O0


Itsu
   
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All,

The Mystery is solved and unfortunately there is no OU in the "E" series circuitry.  I found it odd that by adding more mosfets in parallel, the capacitance increased but the resonant frequency did not.  With the high load resistance, the current took the path of least resistance which happens to be the scope probe capacitance and the parasitic capacitance between components and ground.  It is the energy of the parasitic current that is not being accounted for on the low side current measurements.  The proof of this is when a current probe is used to measure the current from the pulse source and the Math channel uses this in the pin calcs, the COP <1.

So, I will continue to search for any gains using the mosfets but at this time, things look somewhat discouraging.

Regards,
Pm

Hi Partzman,


It is very good you have found the explanation for the high COP for the 'E' series circuit. Would like to add the followings from an answer I was preparing the draft version but some other commitments prevented posting it earlier than your post. Perhaps other readers may find them useful.

"Because your latest setup (Reply #351) operates at 1.3 MHz frequency, the real impedance of the load resistor, R3 is questionable, unless it has a very, very low self inductance and self capacitance i.e. a non-inductive type (albeit in the increasing MHz range even the some nanoHenries start affecting the DC resistance of resistors).

Further, a 4 pF capacitor your blue probe puts across R3 has 30.6 kOhm reactance.
Further, a simple parallel RC of 14.81 kOhm and the 4 pF results in an impedance of Re(Z)=12 kOhm + Im(Z)= -5.8 kOhm at 1.3 MHz and the phase angle Ang(Z)= -25.8 degree." I used this calculator here:
http://www.cirvirlab.com/simulation/parallel_r_c_circuit_impedance_calculator.php

Also, I wanted to suggest to make a parallel LC circuit for 1.3 MHz and put it across R3, this would have tuned out any reactance in  R3 itself and the ill effect of the 4 pF scope probe capacitance. By tuning the LC to 1.3 MHz or to whatever input frequency the setup needs, the voltage across this LC (and hence across R3) would be in phase with the current estimated by R1 10 Ohm csr, so output power could have been also calculated. And what should also be possible, your scope math function could be used for multiplying CH2 by CH4 to get output power after your input power already become known.

Lastly I assume that now the IXDD609 had a higher input current consumption from the 40V DC source than say in the some ten kHz range you used earlier. Was this so I wonder?

Anyway, thanks for sharing and no need for apology, just continue and have fun.

Gyula
   
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  PM - thanks for your diligence and honesty in quickly reporting the mistake.  We all make them.
 And for your continuing research.
"The Mystery is solved and unfortunately there is no OU in the "E" series circuitry. "

   Does this apply to the earlier circuits as well?  (Like those studied at <100 kHz )
   
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Hi Partzman,


It is very good you have found the explanation for the high COP for the 'E' series circuit. Would like to add the followings from an answer I was preparing the draft version but some other commitments prevented posting it earlier than your post. Perhaps other readers may find them useful.

"Because your latest setup (Reply #351) operates at 1.3 MHz frequency, the real impedance of the load resistor, R3 is questionable, unless it has a very, very low self inductance and self capacitance i.e. a non-inductive type (albeit in the increasing MHz range even the some nanoHenries start affecting the DC resistance of resistors).

I was using an array of 15k MOX (metal oxide film) resistors for the loads in these tests and I'm sure they do have some inductance at the higher frequencies.

Quote
Further, a 4 pF capacitor your blue probe puts across R3 has 30.6 kOhm reactance.
Further, a simple parallel RC of 14.81 kOhm and the 4 pF results in an impedance of Re(Z)=12 kOhm + Im(Z)= -5.8 kOhm at 1.3 MHz and the phase angle Ang(Z)= -25.8 degree." I used this calculator here:
http://www.cirvirlab.com/simulation/parallel_r_c_circuit_impedance_calculator.php

Yes, even this low value capacitance probe did affect the measurements in the MHz range.

Quote
Also, I wanted to suggest to make a parallel LC circuit for 1.3 MHz and put it across R3, this would have tuned out any reactance in  R3 itself and the ill effect of the 4 pF scope probe capacitance. By tuning the LC to 1.3 MHz or to whatever input frequency the setup needs, the voltage across this LC (and hence across R3) would be in phase with the current estimated by R1 10 Ohm csr, so output power could have been also calculated. And what should also be possible, your scope math function could be used for multiplying CH2 by CH4 to get output power after your input power already become known.

These are  both good suggestions.

Quote
Lastly I assume that now the IXDD609 had a higher input current consumption from the 40V DC source than say in the some ten kHz range you used earlier. Was this so I wonder?


The Ixys 6xx series drivers when used to drive a continuous load in the MHz range have large internal losses and heat up really quick and will self destruct if unchecked.  In the kHz range not so much, so the power drawn from the supply is considerably less.  We (Itsu and I) were abusing them as well by operating them at 40vdc when they are rated at 35v max.

Quote
Anyway, thanks for sharing and no need for apology, just continue and have fun.

Gyula

Thanks,

Pm
   
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  PM - thanks for your diligence and honesty in quickly reporting the mistake.  We all make them.
 And for your continuing research.
"The Mystery is solved and unfortunately there is no OU in the "E" series circuitry. "

   Does this apply to the earlier circuits as well?  (Like those studied at <100 kHz )

I think the answer to your question is "yes" but just in case, I'm taking time to re-evaluate the various topologies to be absolutely sure.

Pm
   
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  Thanks.
   
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... .-.. .. -.. . .-.
Have just checked which drivers I have on order and they're the IXDD version.
Thoughts may well be correct of them being inferior, particularly from the 1:1 swapout.

Pm - It would be awesome to discover the best topologies use <20V in the low frequency ranges !
But am certainly in agreement with others. Your routing out of possible causes for effects is appreciated. Any new circuit design is taken a lot more seriously than from someone who would cover over mistakes  O0


---------------------------
ʎɐqǝ from pɹɐoqʎǝʞ a ʎnq ɹǝʌǝu
   
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All,

I have done what I consider to be extensive testing of all the topologies presented in this thread and have concluded that unfortunately,  none have the ability to produce COPs>1.  I have learned that as good as our scopes are these days, they have their limits when measuring low level waveforms. 

The Tek MDO series has the ability to scale the input levels if the probe is used for current measurements which in addition to being convenient means the channel offset is reduced by the scaling factor used.  So, I used 20 ohm CSRs to measure the circuit current which meant the scope amplifier was adjusted to 50ma/volt reducing the offset by 1/20.  This allowed consistent and relatively accurate low level current measurements to be taken which then resulted in measurements indicating COPs<1.

Thanks to all who participated in this effort and I truly wish the outcome had been different!

Regards,
Pm 
   

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Buy me some coffee
Thanks Partzman

Been a very interesting project, even though the end result is COP <1 there's a wealth of information and data been produced which people can learn from for future use.
   
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...

Thanks to all who participated in this effort and I truly wish the outcome had been different!

Regards,
Pm

Hi Pm,

I also thank all your efforts and willingness to share.

I hope Brad is ok and would also share his findings unless he also finds his scope has played some tricks with him.

Gyula
   

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Buy me some coffee
Hi Pm,

I also thank all your efforts and willingness to share.

I hope Brad is ok and would also share his findings unless he also finds his scope has played some tricks with him.

Gyula

If i calculate the instantaneous power measured by the scope,and divide by duty cycle,i get consistent COPs of 180-190 %
If i set the scope up as TK showed me,where ch1 is set to voltage,and ch2 is set to amps,the scope calculated watts in is within +/- 1% of the total calculated P/out.

So,i do not know if the manually calculated COPs are correct,and the scope is making a mistake when making it's calculation's,or the scope calculated P/in is correct,and manual calculations cannot be used in this system ?.

I have always thought that if the current and voltage traces are exactly in phase,and a very clean square wave,that instantaneous power calculated,divided by duty cycle, always gives you the correct answer. But in this case,the scope calculations seem to disagree.

As we know the laws today,it would seem that the scope's calculations are correct,and all is as it should be.

On a side note,i have been working on a little something else.
Who here has one of the !drinking birds! ?.


Brad


---------------------------
Never let your schooling get in the way of your education.
   
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Hi Brad,

Well, I mainly meant the "inherent" problem Partzan's Tektronix scope manifested as he described in Reply #368, hopefully in the Rigol scopes there are no "inherent surprises" to lead the user astray. 

The message perhaps is that too good results measured by a scope need to be checked by other means too or find ways to circumvent the scope shortcomings. Often,  this is not easy.

Gyula
   
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OK, this is a re-visitation of the basic FWB version of the Parametric Charger that was first disclosed in posts #9 and #16 on the first page of this thread.  From there, things sort of got off track and I have myself to blame due to my suggested "improvements"!

This inline version does not suffer from any capacitive coupling across transformer windings plus this test does not use a current probe but rather a 10 ohm Caddock precision film CSR with a RF probe connections on a 10M-4pf probe that is setup and calibrated for 100.0ma/volt.

Previously, attempts were made with this technology to run continuously with a given resistive load.  Although this might yield slight gains, the best performance is to operate this type of device in an open rather than closed circuit.  IOW, we allow the parametric capacitance to charge a fixed capacitor to a given level that requires a certain input energy.  We would then discharge this capacitor into a suitable load to realize any gain.  This process would be repeated for a useful OU device.

The schematic below shows the circuit used.  The main difference from the original is the removal of C2 the series capacitor and the addition of the CSR.  The circuit is basically a full wave bridge driven by a high frequency square wave pulse that charges the film capacitor C1.  The top of C1 indicated by the plus sign is the most positive terminal during operation.  The substrate diodes for each mosfet provide one means of charging C1 while the reverse bias parametric capacitance of the mosfet's drain-gate/source junctions provide the other means.  At the correct frequency, L1 in conjunction with the parametric capacitance, provide a reactive input means that effectively reduces the input energy requirement.  This is the gain mechanism for this type of device.

The first scope pix shows the Pin of 22.29mw over 44.1ms which allows us to calculate the input energy with 22.29e-3*44.1e-3 = 983uJ.

The second scope pix shows the scan for the voltage charging of C1.  In this case we use the beginning voltage level of 25.54v and the ending voltage level of 44.81v to calculate the energy in C1 which is (44.81^2-25.54^2)*3.94e-6/2 = 2.67mJ.  The apparent COP = 2.67e-3/.983e-3 = 2.71 .

These measurement are consistent and the next round will involve testing from a biased state in C1 although some testing has already been done in this area.

Regards,
Pm   
   
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Hi Partzman,

I've always found this line of thinking very intriguing. I think it was in about 1991 that I tried to get extra energy out of varactors but I just didn't know enough electronics to do it. (Don't know much more now!)

I can see that this version doesn't suffer from the capacitive coupling and offset issues that plagued your earlier tests.

Here's me being dumb-- what's the purpose of C1? Wouldn't the presence of fixed capacitance just lower the overall change in C and reduce the parametric amplification?

And for that matter, although the mosfets have obvious advantages over varactors, the varactors can have C ratios > 15, inherently giving more bang for the buck, I think.

It's good to be back!

Fred
   
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