TK,
You still want to go for high inductance; as high as possible for as few as possible turns/DCR. I can probably do even better than Orbo by increasing the L/R ratio of the coils. The rise time is not an issue with high inductance and a non-linear core, as long as it is driven well within its saturation range, which is part of the Orbo "secret".
The idea I believe is to make the core act as an inductance "switch" (square B-H) with a relatively low threshold (low Hc).
There's one problem with a low DCR however, and that is high I(coil). This may indeed be why Steorn is using the rheostat and changing it when switching the drive circuit between the conventional pulse motor and the Orbo motor. This however goes against the logic of voltage drops in the circuit with a high R(Limit) value and low coil DCR. The voltage drop would be excessive. If the R(Limit) is kept low, then coil current will be excessive (assuming core saturation is reached).
This is a constant occurrence for me in trying to crack this thing. Certain elements of the design adjusted a certain way make perfect sense in one aspect, but are in direct contravention with other aspects, and vice versa.
To paraphrase Sean: "It's all in the structure and arrangement of the coils". Sounds like Steven Mark talk.
Regarding the Steorn premise:
...does that "net of Joule heat" [red trace] legitimately correspond to the actual energy transferred to the rotor?
IMO, no. That net energy is ONLY representative of the energy lost to the resistive part of the coils. Let's pretend for a moment that we have a super-conductor coil in its place and its DCR is effectively 0 Ohms. The red trace would look very similar but instead the neg excursion would return back to 0mJ every cycle. So what? It still took a fair bit of energy from the source to create the magnetic field used to polarize/saturate the core. The energy stored in the coil is then transferred to the other circuit components (D1 and R(Limit)) as before, but this time with 100% efficiency (as opposed to the 83% shown in the red trace). So in this case the "net of Joule heating" in the coil is
nil. Will this translate into higher rotor RPM or torque? IMO NOPE. What it DOES mean, is we can use a little less energy from our source to saturate the core to the same level as before.
And, further, if Sean is correct about the energy per rev out from the "sense coil", is it a fair comparison to make: (Actual energy transferred to rotor :: Energy out from sense coil) ?
It's absolutely not a fair comparison at all. From the blue integration trace, I'd say the Orbo coils are achieving an energy transfer efficiency of about 95%, which is probably as good as one can achieve without bringing the wire temperature down. If we could somehow make the n=100, then Steorn would want to claim a COP = infinity. That is completely false because we know it still takes energy to create that magnetizing force. Now, if Steorn had super-conducting wires throughout, and a super-conducting SSR switch, then in combination with their super-conducting coil (and no core loss), they
might have a system that was OU. However, we know that IF we had RT super-conductor wiring available to us, there are far better ways to make energy and achieve OU. In summary, no; the net Joule heating in the coil and the energy being generated in the pickup coil are not related at all. I think most agree that the only fair comparison is energy in (i.e. from the battery) vs. energy out. If this was done, Orbo would be seen as grossly UU.
Steorn has demonstrated a few different ways, that apparently the coil energy and rotor motion is "decoupled", i.e. there is no bemf, and no greater current required to energize the field with the rotor mag at TDC. If we buy into this notion (and I am willing to at this point), then I can not simulate the rotor as an energy take-off from the system. I believe I can treat the coils as if they were transformers though, and load them that way, but I don't think that's what we want to do.
.99
"Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa
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Topic: Steorns December 2009 Demo (Read 102185 times)
