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Author Topic: Parametric Charging  (Read 38085 times)
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PM, Is it a temperature related thing?

I would suggest running a calibration on your scope before taking your measurements, and then compare.

It is suspicious to me that in one case the P(in) are all over the map, both pos and neg, while the next time they are all pos. Suggests to me a change in the offset in the scope somewhere.

I normally recal the scope after a warmup period and the TCP0020 current has a degauss/auto zero that I initiate before doing a scan or sweep.  This doesn't mean there isn't some kind of offset or other equipment problem but those variations seem to be due to the outside weather conditions.  The first time I experienced this, I fought measurements all day that were consistent but different from the previous day.  The difference was the weather.  When it clears off, I'll run the same tests again for comparison.

Pm
   

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It's not as complicated as it may seem...
Right, it was strange to me as i thought that the DMM's would also show rms values, their not, thanks.

A DMM can indicate accurate RMS values under 2 conditions only:

1) for standard DMM's, when the wave form is pure, or close to pure sine wave, and it is below say 10kHz.

2) when the DMM is a "True RMS" meter (can be expensive).
   
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PM I noticed in an earlier post you were using a plug board to build on, these are well known to induce pf capacitance onto the traces, which would very likely be humidity responsive.
Although if air conditioned then maybe not, maybe affecting your house ground rod if it has one.

Yes, I have used the plug boards for certain circuits but not in this case as everything is soldered and wired.  I have given the inside humidity some thot and I presently don't have a meter in my lab to measure it but I guess I need to do that.  At the moment it still remains a mystery!

Pm
   

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Poynt99, PM,

thanks for the replies, i was trying to get a handle on what signals i see and what the math function is doing with
them to get the result.
Seems its more complicated then i expected.

Guess it needs some further study from me, so lets leave it that so we don't further clutter up this thread.

 
Itsu
   

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A DMM can indicate accurate RMS values under 2 conditions only:

1) for standard DMM's, when the wave form is pure, or close to pure sine wave, and it is below say 10kHz.

2) when the DMM is a "True RMS" meter (can be expensive).

OK,  i have a Fluke 8060A/AA which says TRUE RMS MULTIMETER, so i will use that in the supply lead to see how it compares to the cheaper DMM's i use now.

Itsu
   

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It's not as complicated as it may seem...
Ah the 8060A, an oldie but a goodie. Nice, and good for you Itsu!

- RMS measurements to 100kHz
- Crest Factor 3:1 (peak to average ratio capability, determines ability to accurately handle spikey signals.)
   
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OK, this is a continuous running loaded test of the circuit that produced the 9418A data table in post #165.  The schematic can be seen in post #9 except the frequency is 710,611Hz and C2 is 2108pf.

The first scope pix shows the power input to be 6.664mw.  Make note of the mean current offset of +150.4ua which would typically influence the average power input to a higher level than would be seen with a perfect 0.00ua offset.  The yellow trace is the input pulse to L1, the green trace is the input current, the red trace is the Math, and the blue and pink traces are the differential voltages across C1 and the load.  The current probe has a 4 turn loop for amplification but the correction factor is 3.883 in the math calculation which is correct according to the profiling of the probe with said loop at this frequency.

The second pix shows the mean output of 18.87 volts across C1 with a 32.1k carbon film resistor as a load.  From this we calculate the output power = 18.87^2/32.1e-3 = 11.1mw.  This is flea power but real IMO.

Therefore, the apparent COP = 11.1/6.664 = 1.67 which is a little higher than I anticipated according to the 9418A data table. 

Again, using the delta energy taken from the data table say between 40ms-140ms, the energy differential of C1 is (33.51^2-17.06^2)*3.94e-6/2 = 1639uJ.  This equates to a potential power level of 1639e-6/100e-3 = 16.39mw.  If we desire this power to be produced at the voltage level at the peak gain point in the table at 80ms, the voltage would be ~24v.  Therefore, the load resistor should be Rl = E2/P = 24^2/16.39e-3 = 35.14k.  I used a 32.1k which lowered the output but raised the COP.

I will use this test as a benchmark for the humid weather and compare it to an identical test run with a dryer set of conditions in the upcoming days.

Pm
   

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Brad

Maybe you have said before, but is your ground floating or real ground as shown in your diagram, if real ground then what is it connected to? apart from the scope ground.

Regards

Mike 8)

Hi Mike

The ground represents the neutral of our power grid,which has the same potential as earth ground,but isolated from it.

Brad


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Buy me some coffee
I don't see any problems in the protocol, but your last question is a good one. Perhaps through capacitive coupling of the windings...

Remove your transformer and short the input leads, and output leads and treat it as a capacitor. See what your capacitor meter measures across the now two leaded component.

I created a simulation of the circuit, and just 100pF from pri-sec has a fairly significant impact on the CVR wave form.

Out of curiosity, have you tried driving this with a proper sine wave at about the same frequency?

I have not tried AC input yet,but will do as soon as i work out what is wrong here.

Tried to measure capacitance the way you said,and cant seem to get a stable reading on the meter.
The battery symbol is not flashing on the DMM,but i will get some new batteries tomorrow,and see if that helps.

At the moment,we are looking for a 192.3% mistake in the power measurements.

Putting aside what i would like it to be,i must stick to what we !believe! to be real,and find out where this measurement error is.

So far i have tried 11 different transformers-all with the E type ferrite core,but only two out of the eleven give these COP>+ results,even though the waveforms all look much the same.
There is nothing special about this circuit. It is just a pulsed transformer,where the secondary go's through a FWBR,and charges a cap. The only thing added is C2--the small 1.4nF cap that is in series with ground and one AC leg of the FWBR.

Tonight i did a self cal on the scope,and nothing changed in way of power measurements--so the scope seems fine.

One question Poynt
Is there a difference between mean and average on the scope,as this new fangdangled 4 channel scope dose not have mean-only average,while my old 2 channel Atten has both.

Too many times in the past,when i though there was really something there,it bit me on the backside,as it always turned out to be something missed that was staring me right in the eyes all along. So this time im looking for a mistake-->there must be a mistake somewhere--right ?.

I have about 8 or 9 of the second transformer i found that showed the !!apparent!! OU results,so ill put another circuit together tomorrow night,and see if we get matching result's,or different results from the same type of transformer.

Anyway,need sleep.
Will report back tomorrow night.


Brad


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All,

This is the variation of the original PC circuit which takes advantage of several things, one of which is there is only two parametric elements, another is the fact that C1 is now ground referenced making current measurements simpler, and yet another is that the fixed series capacitance is integrated into the bifilar windings distributed capacitance, and last but not least is the absence of any magnetization current that would be present with an additional primary winding.

Although the circuit appears to be simple, the operation is not.  Referring to the schematic below, if the 14N05Ls were replaced with a non-parametric diode, C1 would charge to 1/2 the power supply minus one diode drop with a 50% duty cycle.  So, if a voltage across C1 is greater than 1/2 the supply voltage, it is a result of the parametric pumping action. 

Also what may not be obvious is the action from driving the center tap of the bifilar windings.  Since the are bifilar, they are tightly coupled magnetically and electrically.  As a result, when the end of P1 is conducting thru the substrate diode to the 14N05L in a somewhat normal fashion, the other end of P2 is driving the parametric capacitance of the other 14N05L with an equal magnitude but opposite polarity voltage.

The first scope pix shows a test made with this circuit using a 4x loop and a current probe that compares the current taken at the input with CHR1(wht) to the current taken at the ground side of C1 with CH4(grn).  From this it is determined there is no significant difference so a 10 ohm 1% non-inductive film resistor will be used for the CSR.

The last scope pix is the result of the test taken at 764kHz.  With a load resistor of 32.1k ohm, the output power is 17.2mw resulting in an apparent COP = 17.2/6.673 = 2.58 .

Pm
   

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It's not as complicated as it may seem...
I have not tried AC input yet,but will do as soon as i work out what is wrong here.

Tried to measure capacitance the way you said,and cant seem to get a stable reading on the meter.
The battery symbol is not flashing on the DMM,but i will get some new batteries tomorrow,and see if that helps.
Yeah, I suspected the measurement might be wonky.

Quote
One question Poynt
Is there a difference between mean and average on the scope,as this new fangdangled 4 channel scope dose not have mean-only average,while my old 2 channel Atten has both.
MEAN and AVERAGE are exactly the same thing. Different scope manufacturers use one or the other. No problem, the RIGOL uses AVERAGE.

Quote
Too many times in the past,when i though there was really something there,it bit me on the backside,as it always turned out to be something missed that was staring me right in the eyes all along. So this time im looking for a mistake-->there must be a mistake somewhere--right ?.

I have about 8 or 9 of the second transformer i found that showed the !!apparent!! OU results,so ill put another circuit together tomorrow night,and see if we get matching result's,or different results from the same type of transformer.

Anyway,need sleep.
Will report back tomorrow night.


Brad
I like your attitude Brad, optimistic, yet skeptical and cautious when things don't appear quite as expected.  O0
   
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[snip]

I have about 8 or 9 of the second transformer i found that showed the !!apparent!! OU results,so ill put another circuit together tomorrow night,and see if we get matching result's,or different results from the same type of transformer.

[snip]

Brad

Brad,

What would be interesting IMO would be to take one of those transformers that don't seem to work that are like those that do, and take as many measurements as possible for comparison and then carefully disassemble it so we can see the construction of the windings, etc.  No need to do this at the moment but whenever time permits somewhere down the road!

Pm
   

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All,

This is the variation of the original PC circuit which takes advantage of several things, one of which is there is only two parametric elements, another is the fact that C1 is now ground referenced making current measurements simpler, and yet another is that the fixed series capacitance is integrated into the bifilar windings distributed capacitance, and last but not least is the absence of any magnetization current that would be present with an additional primary winding.

Although the circuit appears to be simple, the operation is not.  Referring to the schematic below, if the 14N05Ls were replaced with a non-parametric diode, C1 would charge to 1/2 the power supply minus one diode drop with a 50% duty cycle.  So, if a voltage across C1 is greater than 1/2 the supply voltage, it is a result of the parametric pumping action. 

Also what may not be obvious is the action from driving the center tap of the bifilar windings.  Since the are bifilar, they are tightly coupled magnetically and electrically.  As a result, when the end of P1 is conducting thru the substrate diode to the 14N05L in a somewhat normal fashion, the other end of P2 is driving the parametric capacitance of the other 14N05L with an equal magnitude but opposite polarity voltage.

The first scope pix shows a test made with this circuit using a 4x loop and a current probe that compares the current taken at the input with CHR1(wht) to the current taken at the ground side of C1 with CH4(grn).  From this it is determined there is no significant difference so a 10 ohm 1% non-inductive film resistor will be used for the CSR.

The last scope pix is the result of the test taken at 764kHz.  With a load resistor of 32.1k ohm, the output power is 17.2mw resulting in an apparent COP = 17.2/6.673 = 2.58 .

Pm

PM,

looking promising, using my trifilar toroid (1 winding unused) 2nF each between the used windings,
5.5uF C1 cap, 32.8K load resistor. 330uH L1 coil and 2x IRF3205 MOSFETs.

Screenshot shows input voltage from IXDN614PI at 40V driven at 764KHz in yellow,
current probe in SINGLE lead between MOSFET driver and L1 coil in green,
math trace in red (yellow x green) = 12.4mW (fluctuating a lot), and voltage across
the 32.8K load resistor and 10 Ohm csr in blue (19.9V).

So input calculated to be 12.4mW, output is 19.9V across 32.8K = 11.95mW for a COP= 0.96

Still wet and rainy overhere.

Itsu
   
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PM,

looking promising, using my trifilar toroid (1 winding unused) 2nF each between the used windings,
5.5uF C1 cap, 32.8K load resistor. 330uH L1 coil and 2x IRF3205 MOSFETs.

Screenshot shows input voltage from IXDN614PI at 40V driven at 764KHz in yellow,
current probe in SINGLE lead between MOSFET driver and L1 coil in green,
math trace in red (yellow x green) = 12.4mW (fluctuating a lot), and voltage across
the 32.8K load resistor and 10 Ohm csr in blue (19.9V).

So input calculated to be 12.4mW, output is 19.9V across 32.8K = 11.95mW for a COP= 0.96

Still wet and rainy overhere.

Itsu

Itsu,

I have discovered a problem with the circuit in that it is not operating as it should.  You will notice that if you lower the frequency to a point, the circuit goes unstable.  It has hysteresis so you will have to raise the frequency considerably to exit that unstable mode.  This is not the only problem however so I'm working on solutions and will post as soon as I find a solution.

Regards,
Pm
   

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Quote from: PartzMan
...if you lower the frequency to a point, the circuit goes unstable.

Are you able to identify the frequency at which the instability
begins?  What do you suspect may be causing this?


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Brad,

What would be interesting IMO would be to take one of those transformers that don't seem to work that are like those that do, and take as many measurements as possible for comparison and then carefully disassemble it so we can see the construction of the windings, etc.  No need to do this at the moment but whenever time permits somewhere down the road!

Pm

Hi Pm

I have already tried to take apart some of those transformers,but there all glued together,and dam near impossiable to get apart without breaking the core.

Actually,i should have a look and see if the two i have that show this OU effect are glued together. Graham actually mentioned something along these lines before.


Brad


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Are you able to identify the frequency at which the instability
begins?  What do you suspect may be causing this?

The frequency is variable depending on the supply voltage and parametric device(s) used.  To better describe the instability, one can carefully reduce the frequency and as a result, the voltage across the loaded C1 will increase accordingly but at some critical point, the output across C1 with load will suddenly rise to it's maximum which is dependent on many factors.  This is due to the negative delta "C" or decrease in capacitance of the parametric device due to the increasing voltage across it.  The device is always resonating as some frequency but the device becomes a highly non-linear resonant oscillator at the critical point and rises in frequency to"lock" into it's highest frequency of oscillation depending on circuit parameters and voltage.  It is not very efficient in this mode much less OU.

I don't know if many have noticed but in my profiling of the mosfets I included a profile of a 24mm piezo element which has a positive delta "C".  Solar cells also exhibit a positive delta "C" and I plan to test both of these in the near future.  Wouldn't it be wonderful if a solar panel could produce energy in the dark!

Again depending on circuit values and critical adjustment, I have seen a device have bursts in and out of this critical mode and if captured, the steady state portion below the critical point is highly OU but uncontrollable at this point.

Hope this helps.
Pm

Edit: As I re-read post I really didn't communicate this very well.  The basic working principle is that the device has a self resonant frequency (SRF) frequency based on the series inductance and the series parametric capacitance.  As the voltage rises across C1, the parametric capacitance rises and creates a higher self resonant frequency.  If this SRF rises above the generator frequency, we have instability.
   
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PM,

looking promising, using my trifilar toroid (1 winding unused) 2nF each between the used windings,
5.5uF C1 cap, 32.8K load resistor. 330uH L1 coil and 2x IRF3205 MOSFETs.

Screenshot shows input voltage from IXDN614PI at 40V driven at 764KHz in yellow,
current probe in SINGLE lead between MOSFET driver and L1 coil in green,
math trace in red (yellow x green) = 12.4mW (fluctuating a lot), and voltage across
the 32.8K load resistor and 10 Ohm csr in blue (19.9V).

So input calculated to be 12.4mW, output is 19.9V across 32.8K = 11.95mW for a COP= 0.96

Still wet and rainy overhere.

Itsu

Itsu,

Keep the circuit intact and try it again when you have dryer conditions.  I'll be curious to see your results at that time.

Pm
   

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PM,

ok, will do, will be somewhere around next summer  ;D

I see what you mean by unstable, lowering from 764 to about 450Khz the current starts to increase in bursts
and around 250KHz its stable high current again, but at terrible COP.

Will play around some more.....


Itsu
   
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Itsu,

Here is an optional circuit if you wish to try it.  This will not be as touchy around the unstable point so should be able to see positive results even in your humidity.

The schematic is below.  Remove T1 and leave your two IRF3205s in parallel and drive directly with your 330uH L1.  Split your power supply so you also have +20v dc and connect the end of C1 and the load as shown if you wish to use your current probe.  Make sure your pulse generator is set at 50% duty cycle for this as what we are doing is eliminating any dc bias on the load and/or any coupling cap.

If you use your current probe, use your Math channel to multiply the output of your mosfet driver times the current waveform and have the Math measure in "mean".  For the output measurement, I prefer to do a differential measurement across the load resistor but you could use just the "mean" measurement of CH2 for example, then subtract 20v dc from that reading and do the calculation manually with the difference.

If you wish to use a CSR, then connect as shown.  In your case, you will need to do a differential measurement across the CSR and save in a Rx or reference channel.  You can then do a separate Math multiplication with this measurement and your driver output to get the power input.

In either case, have the "mean" measurement of current displayed so you have the offset current measured with the probe or CSR as this value must be multiplied times the 20v dc supply for a power corrention to the input.  If the value is positive, you are actually supplying power to the +20v and if negative, you are drawing power from the +20v.  The idea here is to get that value as low as possible.

To tune the device, start at say 600kHz and lower the frequency by 10kHz steps until you see the output voltage across C1 rise reasonably quick to it's maximum.  It should be a rather 'soft' instability that you will see.  Whatever frequency this happens at, you want to run slightly higher to do the measurements.  There won't be as much hysteresis but you will need to raise the frequency some to get out of that unstable mode. Repeat this until you have as high a voltage on C1 as you can without the instability and then capture the screen and do your tests.

I've attached scope pix of my own tests with this circuit using IRF740s which appear to be close to the IRF3205s but you should run at a slightly lower frequency than the 560kHz I used.  Note that the offset current is consuming ~2mw from the 20v dc supply.

Pm

Edit: I haven't tried this but the 20v dc supply could be replaced two electrolytics of equal value between the 40v supply and ground.  They should self adjust the offset current to zero.  The 'lytics should have a value of least 10x the value of C1.
   

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PM.

i rebuilded my circuit as to your last post.

Starting at 600KHz i get the screenshot below.

Yellow / green are input voltage / current (probe)
Red is math yellow x green for input power which is negative.
blue and purple are across the 32.8K resistor, a Fluke DDM reads 0.325V.

So my initial problem is that the input power calculations show negative values.


Itsu
   
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PM.

i rebuilded my circuit as to your last post.

Starting at 600KHz i get the screenshot below.

Yellow / green are input voltage / current (probe)
Red is math yellow x green for input power which is negative.
blue and purple are across the 32.8K resistor, a Fluke DDM reads 0.325V.

So my initial problem is that the input power calculations show negative values.


Itsu

Itsu,

And the problem is... :) 

Seriously, this is possible with this circuit but as you can see, the voltage and current waveforms are close to 90 degrees from one another so it now takes very careful means of taking the measurements to be sure what the input power is.  You should have a higher voltage across C1 so I would reduce the frequency and increase the this voltage which will increase the input power and hopefully show an overall gain for you.

Pm
   
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Itsu,

Here is another test set of the same circuit.  I discovered that I had not taken the "divide by 3.88" off my math equation in the first test which would incorrectly reduce the input power by that amount so this is a re-run with the 4x loop in place.  I am using the split power supply in this setup.

The input is 3.508mw with an offset of -36.63ua which results in .73mw drawn from the 20v supply for a total pin = 3.515mw.  The output voltage across C1 is 25.77v with a 32.1k resistor which results in a pout = 20.7mw for an apparent COP = 20.7/3.515 = 5.89.

Pm

Edit: The clipping seen on Ch4 is from very high speed transients that do not materially affect the overall current readings.
   

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Itsu,

And the problem is... :) 

Seriously, this is possible with this circuit but as you can see, the voltage and current waveforms are close to 90 degrees from one another so it now takes very careful means of taking the measurements to be sure what the input power is.  You should have a higher voltage across C1 so I would reduce the frequency and increase the this voltage which will increase the input power and hopefully show an overall gain for you.

Pm

Well, negative input should not happen i guess.


Anyway, from 600KHz i went down in 10KHz steps and at 430KHz there is a sudden change, the voltage across
the load resistor jumps up to 14V, and the input power drops to -76mW, see screenshot 1.

So -76mW in, 6mW out.

When dropping frequency even more, a 2th jump happens at 370Khz where the voltage across the load resistor
jumps to 31.6V, and the input power is 331mW, see screenshot 2.

So 331mW in, 30mW out.

Finally continuing on down, max voltage across the load resistor is at 240Khz at 35.6V
But the input is 1.15W, see screenshot 3.

So 1.15W in, 39mW out.

By the way, my IXDN614 gets rather hot after some time.
Using 2PS's, one at 40V, one at 20V,  grounds connected together.

Itsu
   

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When going UP in 10KHz steps from the 1st jump (370Khz), i can go up to 530Khz with increasing voltage from 14 to 19V
across the load resistor (next step drops the voltage to 2V or so) with an input of 14,2mW, see screenshot 1

So 14.2mW in, 11mW out   (this means a COP = 0.77)

But there seems to be a ripple (14Hz) on the blue trace which if i reduce the time setting looks like screenshot 2.

Itsu
   
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