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

[eldarion]

Rich,

Would you mind posting the value of the chokes you added to your setup?  I think it was 30mH, but I am not sure.

I tried adding some small toroidal inductors, and they didn't help very much (or get warm), so they were probably just the wrong value.  I also tried the secondary of a 120V-12V transformer, and while this made an excellent HVAC generator on the primary side, it didn't clean up the primary waveforms at all.

With a 0.025F 200V capacitor bank on the output, along with a Schottky bridge rectifier, and 700ns pulse width at 40KHz F1, 20Khz F2, and 10KHz F3, my setup is drawing about 150mA at 160V.  The capacitor bank seems to have a power input to it of about 20 watts, so once again very close to unity.  Engaging the HV potential is still making no difference, and I know it should be making a large one!  The only thing I can figure is that my primary waveforms are still just so noisy that I am getting almost no energy collection.

I can't even try to loop the system yet because my inverter and controller are sucking down about 8W at idle.  To be able to loop the system, I need to see the capacitor bank charging at a rate that is about double the TEM input power.

I looked for the snap-together ferrite cores, but I am not sure which variety you were suggesting--my guess is the ones where you loop the wire several times through the core.

Also, could you post a scope shot of your cleaned-up primary waveforms?  I would like to know about how much improvement I should be expecting.

Thanks!

Eldarion

EDIT:  What you are suggesting sounds an awful lot like an AC line filter(http://my.execpc.com/~endlr/a_B2.gif).  Could you try putting one in your setup instead of the chokes and see if it has the same effect?  These things are very common, and if it works just as well as the discrete choke solution it will take a lot of guesswork out of that part of the design process.  (Obviously you would just leave the Earth ground connections in that diagram disconnected).  They suggest these values, which sound pretty close to what you had mentioned.
C1=0.1 uF (the X capacitor)
C2=4700 pF (the Y capacitors)
L1=22 mH common-mode choke
R1=1M ohm bleeder resistor

[Grumpy]

yup...

[eldarion]

Hi Grumpy,

I will definitely take that into consideration.  Right now, my top priority is replicating Bob's setup, which uses the "long" pulse widths in the hundreds of nanoseconds.  Once I get something working, then I can start varying the parameters (trying shorter pulse widths, etc) and see if the change is enhancing or killing the energy generation.

All,

I was able to locate two large inductors in an AC line filter.  An educated guess would put them at somewhere between 50mH and 70mH.  Placing them in the locations designated caused one of my IGBTs to blow--I will assume this is a good sign, as I may have cohered some energy that overloaded the IGBT.  (There was no reason for it to pop on its own--besides changing the inductors, I did not touch any part of the setup, and this setup has been running off and on for a couple of weeks now with no problems  Also of interest, the middle frequency IGBT blew, not the highest or lowest frequency IGBTs).

Now I know why Rich was warning me about using 160V!   I will see what I can do to prevent this in the future (probably scale back to 80V or so for now.)

Just to reinforce this for everyone: the choice of the inductor's value is CRITICAL.  Too low, and no filtering will take place.  Too high, and the core will slowly build up a magnetic field, and once again no or very little filtering will occur.

Hope this helps some experimenters out there!

Eldarion

[Rich SAS]

Hey guy's, got some more pictures to post. Showing the chokes, split cores, scope shot, votage and current. Some pictures of the setup and the 450 farad cap bank I am charging.Ã,  Please forgive the mess.Ã,  ;DÃ,   Eldarion, I don't have an inductance meter, so I can't tell you what the inductance values are, sorry.

Rich

[eldarion]

Thanks Rich!

From looking at your chokes, they may be of a similar value to the ones that I scrounged up--the only difference is that mine are not toroidal.  My waveforms (without chokes and with the wrong value chokes) did not look nearly as clean as those, so that is probably the issue.

I like your capacitor bank.

Eldarion