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Author Topic: Graham Gunderson's Energy conference presentation Most impressive and mysterious  (Read 193105 times)

poynt99

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I've taken the liberty to provide a possible starting point for the simple block diagram.

Let me know of any changes needed.

Spokane1

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I've taken the liberty to provide a possible starting point for the simple block diagram.

Let me know of any changes needed.

Dear poynt99,

That is a good start. Let me add to it with my Version 1 Block Diagram.

In the actual presentation the input energy was measured at the input of the conversion transformer after the 220 VDC linear power supply and the H-Bridge switcher.

On the back end the oscilloscope made its connections to the capacitor bank while the power analyzer connected directly to the automotive lamp.

Spokane1

poynt99

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Very nice Spokane1. Obviously you've made a few diagrams in your time.  ;)

One thing that sticks out immediately, is the logic controller feed to the output driver chips (the stage before the output storage caps). I would strongly urge Graham to measure the power being delivered by that feed to make sure it isn't adding significant power to the output.

The other alarm bell that is going off for me is the fact that that same output driver stage has 3 power supplies in it. They too could indirectly be contributing power to the load.

There could indeed be significant power being sourced by the logic controller and the power supplies I mentioned above, but determining if a significant portion of that power is getting to the output could be tricky.

If they are sourcing only milliwatts of power, then obviously they are not an issue. However, if the measured power is significant relative to the output power, then further investigation should ensue.

It would be nice to see detailed input power traces on the scope, and how the power was being computed (no. of cycles, MEAN, etc.). The output power measurement could be getting skewed by what I mentioned above, but the input power measurement seems more interesting since it apparently can go to 0W. I've seen that before and it was attributed to parasitic wiring inductance that was not compensated for. Once corrected, all was back to normal.

poynt99

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Regarding the input power measurement and a potential source of error;

1) how long is the wiring between the h-bridge and the transformer?

2) which end are the current and voltage probes placed, near the h-bridge end or the transformer end?

Spokane1

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Regarding the input power measurement and a potential source of error;

1) how long is the wiring between the h-bridge and the transformer?

2) which end are the current and voltage probes placed, near the h-bridge end or the transformer end?

Dear poynt99,

I can take a shot at these two questions. The Oscilloscope current probe is connected right at the Swinging Choke and Capacitor array resonant tank, right were the Litz wire from the Conversion Transformer Primary lead connects. The Scope differential clamps connect across the capacitor array. So does the voltage connection for the input power analyzer. It is not to clear to me just where the Input Power Analyzer gets its current information from without studying the photo more closely. Reiyuki has a nice photo of the top of the capacitor array where you can see all these connections. I don't have that photo at home yet so I couldn't attach it this evening.

So the current and voltage probes for both input instruments are connected closer to the H-Bridge. There is about 8-10" of Primary lead in Litz wire that is of equal length coming from the transformer.

You bring up some good technical questions in your last post that need to be addressed.  Right now I don't know for sure where the H-Bridge and the Synchronous Diode Drivers get their power. Most likely it is from that 5 voltage regulator on the logic controller coming in from those shielded ribbon cables, but it could be from the process itself.

Since the input power is measured after the H-Bridge then what ever energy was added to the input flow from the H-Bridge would be measured as part of the input power to the transformer.

The real question is to understand what is going on in the Synchronous Diode section.  Do you happen to know what the upper limit of leakage power might be from a FET gate to the source-drain current path? I'm sure there is some. Would it be in the data sheet? Better yet, how much energy does it take to run his driver circuit? Lets see 10 mW, maybe 100 mW at the most. The automotive lamp was consuming about 10 watts or 10,000 mW so even if the entire gate driver energy were delivered to the output measurements we would be in error of 100/10,000 or about 1%.

I know this is a cheap way to look at the energy balance situation, but until we learn more about the details of that backend power supply this is what we have to go with for now.

Let me share some thoughts on those driver power supplies:

They are not simple. This is where the advanced electronics is going to be found. It will certainly separate the masters from the armatures. Look at the photos and attempt to start figuring out how that thing works. I know what it does. It provides the three voltages to run the driver IC's -5, +5, and +12. Graham uses negative bias to shut the FETS off and then over drives the gate to +12 volts (maximum is suppose to be +10) to turn it on. The +5 volts runs the logic on the driver IC itself.

Graham does not use gate resistors for his switching FETS. He has thus developed an approach that maximizes the performance of some pretty fast devices.

It appears that the backend network is composed of two power supplies so that each driver IC has its own power source. If I understood Graham correctly those three opto isolators on each end of the board are zener diode optos, they turn on when a certain voltage is reached, these are used as the voltage feedback sensors to operate the PWM's that drive that complex toroid transformer in the center of the circuit board. The idea is to use only as much energy as necessary. I'm sure there are several implementations to achieve the three required voltages. His is a work of art. There are also a number of additional components underneath that
circuit board that no one got a photo of.

I don't think that the method employed to provide power for the driver IC's is going to be a game stopper issue. Who knows maybe someone will discover that a single voltage driver will work as well, better yet a discovery that we don't need the super switching speeds that SiC components deliver (I can dream can't I).

Have a nice weekend,

Spokane1

gotoluc

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Good morning Gotoluc,

Going to try this again, first post never showed up. Could you post a picture of the setup that made this waveforms.
Your description as to how it works and built is easy to understand.  Any description
of the exact construction of the coils/core/magnet assembly would really help.  Your device
is electrically so much simpler that Gundersons and the aux. cicuit to harvest the output pulse during the rest would be just as simple.
This is going to be my first try at replicating your circuit..

Respectfully

Ben K4ZEP


Hi Ben,


nice to see you here :)


the coil was around 10mH with a ferrite core. Use your signal generator (at 33% duty cycle) to turn on and off the mosfet's current to the coil which has a .002uf  to .005uf cap connected in parallel across it. Tune the frequency till you get (single Wave Ring) Resonance.


Kind regards


Luc

Spokane1

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Thank you, but it doesn't really help me much. I'd rather not speculate.

The pictures almost raise more questions than they answer; for example, why are there two scope probes on the output circuit side? Is he doing a differential voltage measurement and using A-B math on the scope?

I would suggest if you do come up with a diagram, post it here and also send it to Graham for his review and approval. If he gives it a thumbs up, then at least we have a starting point.

At the moment, I have no idea what the input source is even.

Dear poynt99,

According to what Graham said in the lecture he was using a single 10X 10 Meg probe for his output scope voltage measurement. The second probe was used to temporarily connect to a different part of the circuit for a different scope shot for some topic in the presentation. You will have to wait for the DVD download the fill  in the details,

He used the differential voltage for the input scope voltage measurement because of its magnitude of 800+ Volts

Graham is not going to review my drawing and I'm not going to approach him until I have built a functioning where I can show him all the switching wave forms and what ever performance I can measure. Then I shall be ready for the master to bestow upon this novice the next step in understanding.

Scope math was used for both the input wattage and the output wattage. The data was parsed at 10 MHz and multiplied and then integrated to produce the real time wattage measurement.

The input source is a common linear Full Bridge Rectifier 220 VDC power supply with an inductor and a large capacitor for the filter section. The transformer was a 120VAC to 220 VAC ratio unit. I would say it would be rated at about 300 watts. We have some good photos of this power supply. I was going to bring them out when I compose the schematic. Since this is such a trivial part of the apparatus I haven't brought it up. I'm going to use a surplus B+ supply that has a regulated variable output - the price was right.

again Have a good evening

Spokane1

Spokane1

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Hi Ben, nice to see you here :)
the coil was around 10mH with a ferrite core. Use your signal generator (at 33% duty cycle) to turn on and off the mosfet's current to the coil which has a .002uf  to .005uf cap connected in parallel across it. Tune the frequency till you get (single Wave Ring) Resonance.

Kind regards

Luc

Boy that sounds interesting!

Spokane1

TinselKoala

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If a component or subsystem is necessary for the operation of a device, then the input power to that component or subsystem _MUST_ be included in the "input power" measurements of the device. Especially when overall COP is concerned. Anything else is not only incorrect... it is dishonest.

It is kind of like saying that the cost of a car trip is just the cost of the gasoline. Of course the _true_ cost of any car trip has to take into account the cost of the car itself amortized over its lifetime, maintenance, oil, wear on tires, insurance, registration, safety inspection and etc. All these items must be paid for in order for the car trip to take place.

Similarly, all necessary components of an "ou" device that receive power from any source -- especially from conventional electric power supplies -- must have their input power included in the input power to the "ou" device.

To answer one specific question about mosfet leakage from Gate to the Drain-Source circuit, consider that the mosfet Gate is essentially a capacitor. Like any other capacitor it can leak AC power to the Drain-Source part of the circuit. How much depends on the actual capacitance and the frequency and other parameters of the drive. If the power supplied to the Gate drive circuitry is ignored, and the power being switched by the mosfets themselves is ignored... yet these components are needed for the device to work.... why, using these tactics just about any device can be claimed to be "overunity" by a large margin.

For example, take my "microQEG" device. Since _all_ the input power to this device is being used to drive the mosfet gates, and is being switched by the mosfets themselves, I can just ignore it, just as the input power to Gunderson's H-bridge and synchronous rectifier mosfets is being ignored. So my device runs on _zero_ input power, by the same logic that seems to be used in saying Gunderson's device uses "0.000 watts" input power. And it lights up light bulbs too !


TinselKoala

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Regarding the input power measurement and a potential source of error;

1) how long is the wiring between the h-bridge and the transformer?

2) which end are the current and voltage probes placed, near the h-bridge end or the transformer end?

It seems rather obvious to me that positioning a Hall Effect current probe quite near a source of external magnetic field is not "best practice". The external field is going to affect the accuracy of the measurements taken with that probe. For accurate performance the _only_ field anywhere near the probe should be that induced by the current flowing through the conductor being measured.

In fact this is usually mentioned in application notes and instruction manuals for these probes.  When using Hall Effect probes on unknown circuitry, it's a good idea to confirm the probe readings by comparison to current readings taken by another method, such as the voltage drop across an inline current-viewing resistor.


TinselKoala

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Furthermore--- the Clarke-Hess power analyzers with which I am familiar require several connections to a circuit in order to monitor it properly. To monitor Voltage the instrument is connected like any DMM, across the supply. To monitor Current the instrument is patched _in series_ with the supply and circuit being monitored. Obviously to compute a Power reading both connections must be made.

Here's a photo that you might remember, .99. It shows my (borrowed) C-H analyzer, with its patch connections, measuring the input power to a certain circuit of mine which is out of view above the instrument. Note the negative power reading.

I can haz cheezburger now?

poynt99

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Dear poynt99,

I can take a shot at these two questions. The Oscilloscope current probe is connected right at the Swinging Choke and Capacitor array resonant tank, right were the Litz wire from the Conversion Transformer Primary lead connects. The Scope differential clamps connect across the capacitor array.
Ok, that's good.

Quote
So the current and voltage probes for both input instruments are connected closer to the H-Bridge. There is about 8-10" of Primary lead in Litz wire that is of equal length coming from the transformer.
;)

Quote
You bring up some good technical questions in your last post that need to be addressed.
Having additional power supplies in the device casts some doubt on the Pout measurement, and it should be checked.

Quote
Since the input power is measured after the H-Bridge then what ever energy was added to the input flow from the H-Bridge would be measured as part of the input power to the transformer.
I have no issue with the potential for power being added to the input.

Quote
The real question is to understand what is going on in the Synchronous Diode section.  Do you happen to know what the upper limit of leakage power might be from a FET gate to the source-drain current path? I'm sure there is some. Would it be in the data sheet? Better yet, how much energy does it take to run his driver circuit? Lets see 10 mW, maybe 100 mW at the most. The automotive lamp was consuming about 10 watts or 10,000 mW so even if the entire gate driver energy were delivered to the output measurements we would be in error of 100/10,000 or about 1%.
Agreed. As I wrote, these can be checked, and if insignificant, can be ignored. The more interesting part for me is the Pin measurement.

poynt99

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Dear poynt99,

According to what Graham said in the lecture he was using a single 10X 10 Meg probe for his output scope voltage measurement. The second probe was used to temporarily connect to a different part of the circuit for a different scope shot for some topic in the presentation.
That is what I figured.

Quote
Scope math was used for both the input wattage and the output wattage. The data was parsed at 10 MHz and multiplied and then integrated to produce the real time wattage measurement.
What do you mean by "parsed at 10MHz"? I hope he used "MEAN" on the product and not some integration math function to obtain the average input and output wattages?

k4zep

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Hi Ben,


nice to see you here :)


the coil was around 10mH with a ferrite core. Use your signal generator (at 33% duty cycle) to turn on and off the mosfet's current to the coil which has a .002uf  to .005uf cap connected in parallel across it. Tune the frequency till you get (single Wave Ring) Resonance.


Kind regards


Luc

Good morning Luc,

Good to run into you again too!  Thanks for the additional info. A simple and unique way to get this waveform.  Using the original information in your post, knowing the Cap. I had calculated the Inductance to be in that range.
Each little bit of information helps!  My 2 X 4 worlds smallest lab is a mess right now due to finishing up a high end R/C sailplane, but will spend the day cleaning it up,
getting a good sig. gen. out of storage, drag out my power supplies and variac, proto board, Opto Isolater, find a good FET in my junk box,
and I might have some results in a day or two. Due to my limited space, building anything requires removing everything else and setting up what I need for the particular experiment.  A Chinese fire drill!   This concept totally intrigues me!

BTW, do you remember what caused that hash spike or ringing at the start of the "rest" period?  Diode (in FET)/switching transient, etc?

Respectfully
Ben K4ZEP

poynt99

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It seems rather obvious to me that positioning a Hall Effect current probe quite near a source of external magnetic field is not "best practice". The external field is going to affect the accuracy of the measurements taken with that probe. For accurate performance the _only_ field anywhere near the probe should be that induced by the current flowing through the conductor being measured.

In fact this is usually mentioned in application notes and instruction manuals for these probes.  When using Hall Effect probes on unknown circuitry, it's a good idea to confirm the probe readings by comparison to current readings taken by another method, such as the voltage drop across an inline current-viewing resistor.
Agreed.

It also concerns me when I see the diff probe amplifier sitting on top of a large stack of magnets.