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Author Topic: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,  (Read 303052 times)

popolibero

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #270 on: August 06, 2014, 07:30:51 AM »
Hey Barry,


that shouldn't be problem. Even if both switches are ON during the discharge phase the energy can only go from cap to transformer in that moment, as far as I can see.
The sine wave you see on my shot is on transformer primary. The current wave is across the light bulb.
Strange, your wave looks like if you had an inductor in series with your resistive load. Meaning instead of having the current rise immediately it rises slowly, like initially impeded by an inductor. But it still would have to decrease towards the end of the half cycle since cap is being emptied.


Where did you put your probes?


regards,
Mario


popolibero

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #271 on: August 06, 2014, 09:24:31 AM »
Barry, also, I wonder if your mosfets are turning off completely? The switching sequence you had before your last update should actually work, from the transformer secondary point of view, even if the caps alternate, it still sees charge/discharge. That sequence is actually even better because in the last one you did you are not able to control when the cap stops to charge and starts to discharge (sine peak), current can go either way since both your switches are on.
Well the best option is to have 1234 all separate signals, but I don't know if you can achieve that with your circuit?


regards,
Mario

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #272 on: August 06, 2014, 04:53:15 PM »
Hi Mario,

After delaying discharge pulses to around 135 deg, I obtained attached waveforms. 

Just a quick non precision check with an energy meter on the ouput of the transformer, (the line transformer in the amplifier), shows 31W, 85VA PF 0.35

I note the timing is very critical and the current waveform can easily collapse back into 0 phase shift with respect to voltage.

I did manage to fine tune with larger capacitors and got even closer to your waveform however, I had MOSFET failures (all 4 short) not been able to determing cause yet.

This happened when I increased the load, which is a rheostat. I cannot see any voltage transients to speak of, so suspect current transients are the problem,

I was using IRF840s which are good for 8A , 32A pulsed .

I can change these out for some 20A 1200V IGBT's which would be more robust.


Barry

popolibero

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #273 on: August 06, 2014, 05:01:22 PM »
Hi Barry,


where are you putting your probes? If the red wave is across the load I'm having a hard time understanding how your current can rise that way. Is it possible that your rheostat is acting like an inductance?


regards,
Mario

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #274 on: August 06, 2014, 08:19:35 PM »
Hi Mario,

The current probe (clamp on)  is between the load and the switches.

The load is 208 ohm and has an inductance of 249mH

I found the problem that was destroying the MOSFET's. I am using 60uF non polarized caps and I have two more sets of these but I decided to place 660uF electrolytics  in place to make a large increase in capacitance. The problem occured as the range of my timing adjustment allows the charge period to be moved into the opposite phase and the electrolytics were shorting when this happened. I have reverted to non polarized.

Barry

 

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #275 on: August 06, 2014, 08:35:08 PM »
Hi Mario,

This is a photo showing current waveform with light bulb load, about the same 31W.

Not sure whats happening with the negative charge waveform?

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #276 on: August 06, 2014, 08:56:57 PM »
All, appologies for that last photo, forgot to reduce it.

Hi Mario,

The negative charge  waveform distortion was another failed MOSFET..shorted!

Don't know what the problem is now, these are 650V 10A devices.

Barry

magpwr

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #277 on: August 07, 2014, 12:24:11 AM »
All, appologies for that last photo, forgot to reduce it.

Hi Mario,

The negative charge  waveform distortion was another failed MOSFET..shorted!

Don't know what the problem is now, these are 650V 10A devices.

Barry

hi listener191,

To fix/modify thread -The photo just needs to be re uploaded with the smaller size eg:pbrush to shrink photo to 30% on both axis.Do uncheck old photo with similar name.

popolibero

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #278 on: August 07, 2014, 12:49:06 AM »
Hi Barry,


thanks for the pics, man that photo is so big I can't even fit the scope shot on my screen to look at it ha ha ;D .
I see you are using some big caps, that means quite some current pulses, check the SOA curve of your mosfet on the data sheet. Maybe the current is too high for too long for them to handle it.
I don't think we will see reduced consumption on the amplifier, even if the circuit works correctly and gives back almost all it takes, because the amp is a source which doesn't work like a generator (or line which is the same). But once you feel comfortable and your circuit works well maybe you can give it a shot on the line and see what you power meter says about the input with regards to what the load is consuming.
I've ordered the components to build your control circuit.


regards,
Mario

Farmhand

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #279 on: August 07, 2014, 03:39:29 AM »
Hi Mario,

The current probe (clamp on)  is between the load and the switches.

The load is 208 ohm and has an inductance of 249mH

I found the problem that was destroying the MOSFET's. I am using 60uF non polarized caps and I have two more sets of these
but I decided to place 660uF electrolytics  in place to make a large increase in capacitance. The problem occured as the range of
my timing adjustment allows the charge period to be moved into the opposite phase and the electrolytics were shorting when
this happened. I have reverted to non polarized.

Barry

Hi Barry, How come you are using an inductive load ? The load should be resistive so as to dissipate energy and consume real
power for the output. I suggest a large non inductive resistor then you can get load power measurements as well with no
need for power factor calculations.

A non inductive load might help preserve the switches as well. It could be the current surge trying to charge a totally discharged
relatively large capacitor with no current restriction or it could be the inductive load wreaking havoc on solid state switches.

The initial current into a totally discharged 470 uF capacitor from a 120 or 240 volt supply would be significant. like a momentary short.

Just be careful not to measure the power charging the capacitors as output as well as the power when they discharge, the power
consumed by the resistive load only is the output. And to get an accurate input just use a sine wave inverter for the input then
you can measure the DC out of the battery.. Although It would not surprise me if the inverter was destroyed anyway.

Go well.

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #280 on: August 07, 2014, 06:13:29 PM »
Hi Mario & Farmhand,

The rheostat was a convenient high power resistive load, which by its construction, has some inductance.

I have tried two parallel 50W light bulbs instead and it does not change the waveform and does not change the readings on energy monitor i.e. still 31W 0.31PF  95VA.

Have also used 1:1 transformer to isolate my source and placed the energy monitor on the input to that transformer and got very close to same i.e. 31W 0.31PF 95VA

The PF displayed is purely due to the cap switching.

With regards to the load is their some specific measurement you would like me to make?

The AC voltage across the load reads 68V and 0.172A through the load via a true RMS meter.

My current clamp is showing  1A pk to pk.

@Mario,

Re MOSFET failures. I am using P12NM60 MOSFETS which at a VDS of 160V allows about 1.5A continuous to stay in its SOA. I was pushing higher than this at several times during testing so it may well be going outside the SOA. Thanks for making me look at this. I will change to IGBTS at some point to provide some useful current capability and keep the current down for now. I am still using 60uf Non Polarized caps. I guess you are only using low voltage and car bulbs?

Attached is latest SERPS timing rev that allows individual MOSFET switching without adding two more pulse width monostables. As you can voltage control timing clock the additional LTC-6993C-3's may be far neater, as then you can remove the falling edge detectors and the NAND RS latch and all the buffers, inverters and XNOR gates.

The resistor values indicated plus the 470K pots, give a good timing range.

I appreciate any suggestions and happy to make any measurements

Barry


listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #281 on: August 07, 2014, 06:31:22 PM »
I should mention the cyclic RMS current measured on the scope is 0.2A, which inconsideration of the waveform is fairly close to 0.172A measured by the meter in series with the load. So power is somewhere between 11 to 13W in load.

31W & 95VA shown on the input from source.

Babcock and Murray claim 1W input from source and 52W in load?

Maybe need to have measuring setup for load power running same time as input measurement i.e. side by side, to determine if there is any 'sweet spot' adjustment?

Barry


popolibero

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #282 on: August 07, 2014, 10:09:45 PM »
Hi Barry,


thanks for posting all that. We have to keep in mind that the claimed 1.1W input is the differential of the power they take from the grid and the power they give back. t's not simply that the transformer shows 1.1W consumption. I don't remember if they say the numbers, but let's say that for one moment they take 100W from the grid and the next they give 98,9Watts back. The net result is that you pay for 1.1 W.
Now, I don't know if a little power meter can calculate that differential, but since you asked if I wanted you to take some measurements I would like to suggest you put a 0.1 resistor shunt in series with the transformer secondary (or primary) and put your scope across the resistor. This is what they did in the attached picture. If the positive amps are about the same as the negative amps you know that you are returning about the same power you are taking, and since your bulb is lit you know you're in the ball park.
You will not be able to measure a low consumption on your audio amp, because it's not a generator and it doesn't know how to handle the power you send back. If you had a generator as a source it would convert the energy you send back into motive force making the generator become a motor for a moment. This means it would be a generator without drag on the prime mover, and this while running the load.


P.S. Could replace that big picture you posted with a smaller one? It makes reading this page a bit difficult, thanks  ;)


regards,
Mario

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #283 on: August 07, 2014, 10:17:40 PM »
OK not sure if this will replace oversize photo. This one has all MOSFETS working .

Also attached is a photo of the light bulb load and a power meter monitoring load power only.

This was a meter I designed for monitoring generator outputs hence the RPM display and is arduino based. It has an RS-232 output that can be used for data logging and has isolated monitoring.
This one works down to fairly low voltages where the energy meters peg out below 90V or so.

I noted that the software needs a tweak to limit rounding to avoid the PF >1.00 situation.

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #284 on: August 07, 2014, 10:53:30 PM »
All,

In the Murray Babcock presentation time 01:28:45,  Babcock states that in substituting a generator with a transformer, the transformer eats up the returned power. This is indicating that a practical SERPS device cannot work on a transmission line system with transformers.

It would seem that to see this device work, it will have to be placed on a generator!

Barry