Eldarion and Bruce's build of Bob's Energy Converter

[MarkSnoswell]

OK. I cant find any magnetoacoustic resonances in this core. -- not like I can in the ferrite core.

I can hear a sharp resonances at 9.2 KHz and 11.93 Khz.  Mechanical damping confirms these are comming from the core. Spacial beats also indicate these are multipole resonances. I cant detect *any* acompanying electrical signature of these resonances. I probed poloidally and toroidally -- nothing.

The resonances require some magnetic bias -- but once started they persist when the bias has been removed.

That's all I can tell you about this core. Even although I could only hear them it is clear the Q is quite high. This suprised me as the Iorn Powder is quite soft and I had feared that it would damp out all resonances. As the resonances are mechanical and with quite high Q you will be able to hit harmonics of these -- a lot of harmonics.

Hope that helps a bit.

Mark.

[eldarion]

Hi Mark,

Thanks for all the info--I was wondering why I only had the audible resonance, glad to know it isn't just my setup!

Regarding why I wasn't resonating the primary coils, here is a post from Bob.  I may be interpreting it incorrectly, does he mean that the resulting waveform in the primary should look like a unipolar negative spike, or should I be injecting the spike and then allowing the coil to ring?

Hello Gary.

You are correct, if you drive any single winding on that toroid with an AC waveform, you will not see anything but single phase AC output on all the other windings. Where this phase factor comes into play is, instead of driving with AC, you drive each of the 120 degree coils in phase with very sharp and narrow unipolar negative DC pulses. The energies that are in phase will be additive. Now apply a nominal 160 VDC positive bias (through a high value resistor or LPF ) at one end of the single winding that is wound 360 degrees. At the other end of that winding, use a DC blocking cap, and apply that signal to a load (120V light bulb works well). Now as you are applying pulses and bias, start to shift phase very so slightly of phase B and phase C and observe the effects. You will not need to adjust but a fraction of a degree. If you do not see the effects, then your pulses may not be of sharp enough rise/fall times, or there may be too much of an impedance mismatch between the drive and the transformer. Oh, all applied potentials are in reference to earth ground. You may want to compare the results with and without the 160 VDC bias, reversing bias and applied drive potentials, ect.. and note the observed differences.

The other mode is rotational with 120 degrees of phase differential between A to B and B to C, then vary B and C a fraction from that. But I highly suggest you avoid that until you have a control loop set up that can allow you to shut it down very quickly. It can go out of control suddenly and avalanche if conditions happen to be just right.

Bob

Any thoughts?  This pretty much sums up what I have been doing; incidentally this post seems to succinctly and clearly explain how to at least get some energy conversion effects--maybe not at full power to start with, but the working device can always be tweaked later on.

Eldarion

EDIT:  Here's another quote.  This one seems to confirm that resonance is not desired in the primaries, and that any current whatsoever does not help the effect.  I do wonder if the primary drive should be pure electric fields, or if some magnetic component is required?

There are many ways to tap into this LEM pie. Almost all share a common thread, ultra fast pulses of pure electric potential.

EDIT2: Here is another interesting tidbit.  I do not understand the source of my difficulties; this seems easy?

Rotating fields in and of themselves are not dangerous, as electric motors do it all the time. It is rotating fields inside of electrostatic potential fields that can become dangerous. This does not mean that it will always occur, just that there is a great risk of this occuring if things are just right. If it does, there is no advance warning. Without controls in place, it will quickly escalate into a runaway condition that will culminate in an energy avalanche. It is this energy avalanche that will trigger a local lightning strike.

Didn't Grumpy experiment with something like this with the MAGVID whereby he inexplicably burned out one of the stepper motor controllers that he was driving the orthogonal coils with?  But I think he pulsed the magnetic bias in some odd way when the system burned out...

I am so fed up with this not working; if anyone has any ideas I would be happy to try them!  (No offense to Bob, it is not his fault--I am probably just missing something that others are taking for granted. )  My next step is going to be to make sure that I am not swamping the output, as Bob has mentioned before, but after that I'm out of ideas.

I have noticed that the pulse fall time is excellent, but the rise time is rather long because the switched primary end is not being actively driven to +13.8V at that point.  Just another thing to consider...

[MarkSnoswell]

Eldarion -- I just looked back over the thread - no screen shots of signals. Are you able to post screen shots of waveforms -- measured at the coils? It would help to see whats (not) happening.

mark.

[eldarion]

Sure!  Here you go.  I had not posted them because I thought they were too chaotic to be of much help.

Here is the primary coil F3 waveform at 10.0KHz:
http://www.falconir.com/pics/F3_highest.jpg

Here is the primary coil F2 waveform at 20.0KHz:
http://www.falconir.com/pics/F2_middle.jpg

And here is the primary coil F1 waveform at 40.0KHz:
http://www.falconir.com/pics/F1_lowest.jpg

Here are all the signals on one scope screen:
http://www.falconir.com/pics/all_together.jpg

And here are the gate drive waveforms, scoped at the IGBT gates:
http://www.falconir.com/pics/gate_drive.jpg

All of these measurements were taken with the identical settings; 500nS pulse width, 40.0KHz primary F1 frequency, 1-2-4 frequency division, 120.0 P2 phase, 240.0 P3 phase, capacitor and 7W light bulb for load.

Thanks!

Eldarion

EDIT: Fixed some labels

[Grumpy]

Eldarion,

You scope shots look like positive pulses rather than the negative pulses that Bob specified.  My understanding is that you drive the primaries with negative pulses.  I can't see why you would want the primaries to ring, so they should be damped.

Ar your primaries open-ended?  Sorry, I know that is somewhere in this thread and I am being lazy and not looking.