Graham Gunderson's Energy conference presentation Most impressive and mysterious

[TinselKoala]

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]

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.

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.

Having additional power supplies in the device casts some doubt on the Pout measurement, and it should be checked.

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.

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]

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.

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]

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]

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.