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

[MarkSnoswell]

BEMF or not -- I don't know. If you think about it the BEMF is a symptom of current flowing with nowhere to go. On the other hand you can apply and EMF with little current flow. So the question is do we want current or voltage? ... and induced voltage the same as applied voltage? WIth all the information I have seen to date I don't know -- we should be prepared to test everything.

mark.

[eldarion]

Hi Mark,

I would think that letting the coils generate a back-EMF would be quite similar to just applying a fast, narrow HV pulse across the primary coil as you suggest.  It is possible that the primaries are just there to have enough inductance to create these HV spikes; who knows (except Bob!)

I am starting to think that it might be a good idea to let the BEMF spikes occur, as the end result would be a rotating electric field.  There isn't too much in the literature on such fields (which makes them an interesting avenue for research), but I did run across this abstract:

[PP1.109] Stability of a Penning trap with a quadrupole rotating electric field
T. Hasegawa (University of Hyogo, Hyogo 678-1297, Japan), M.J. Jensen, J.J. Bollinger (NIST, Boulder, CO 80305)

We will present theoretical and experimental studies of the center-of-mass (COM) stability of ions in a Penning trap with a quadrupole rotating electric field. The rotation frequency of an ion plasma in a Penning trap determines the plasma density and shape, and it can be precisely controlled by a rotating electric field. A quadrupole rotating-field scheme can control pure single species plasmas in contrast to a dipole field, which is effective only for plasmas composed of two or more species of ions(X.-P. Huang, et al.), Phys. Plasmas 5, 1656 (1998).. However, the quadrupole field can modify the trap stability because of the spatial dependence of the electric field. In this study we theoretically and experimentally determine the COM stability condition for ions in a Penning trap with a rotating quadrupole field. The experimental results agree with the theoretical prediction.

Luckily I can de-suppress the BEMF spikes simply by removing the resistor network.  Now just to rig it so that I don't blow the MOSFETs and drivers...

Eldarion

[MarkSnoswell]

The simplest way to control the BEMF is via the pulse width... you just control how much energy goes in and that is proportinal to the BEMF peak. In practice it worked almost exactly as I simulated.

A very big defference with BEMF is that although the current runs the same direction the generated emf is opposite to the applied emf. If you need unidirectional emp pulses this could be bad --

I will be speaking with Bob tomorrow and I'll bring it up.

cheers

mark.

[Earl]

@All

As I see it, if the back EMF HV-pulse has the correct polarity, the lower voltage pulse has the wrong polarity and therefore perhaps an implied wrong rotational direction.  It is also possible that the relationship concerning the shock to the environment is according to the square of the voltage.  If this is true, than assuming 12V versus 1200V means the wrong polarity has 10 thousand times less effect than the correct polarity.

It is easy to generate back EMF with a switch and a coil; we will see how things work out with, say, avalanche generators.  I am building a custom mini METGLASS core to do some experiments with HV generation.  Will be using 5mm wide METGLASS strips cut myself from a larger 1 inch band, and 5-minute epoxy glue to give rigid structure and eddy-current reduction.  It will be a mess to do, but for 1 or 2 research pieces, why not?

Earl

[MarkSnoswell]

I was just talking to Bob... based on his past experiences he didn't think there was any significant difference between driving primaries closed or open loop -- and therfore no significant difference between apprlied EMF and BEMF.

so -- who knows? I think Earl is right - done corectly the EMF is insignificant compared to BEMF. Aureliano's group (the Mixicans) have also seen that the output is exponentially proportional to voltage.

As for clean signals -- Bob said that you want to apply clean pulses to the coils but that thay can ring however they want -- the ringing is not a problem.

cheers

mark.