TinMan Generator Research Moderated Topic

[DreamThinkBuild]

Hi All,

This may be half baked but looking at general motor 101 design we know that when a wire is subjected to a uniform magnetic field it deforms the field around it.

If the wire is held stationary and briefly pulsed the vectors add to one side of the field while subtracting from the other based on the magnitude/current and falloff.

Attached are some basic references from motor design books.

So here is an interesting thought place a fixed copper bus bar through the middle of two fixed magnets with fixed pickup coils on the top and bottom. Then the bus bar is pulsed with bi-phasic DC or straight AC to shift the field back and forth through the coils.

I've been doing some tests with a fixed coil in a uniform field but haven't tried the bus bar geometry yet. Attached is a picture of one current test setup, it's two 6"x2" ceramic magnets with a fixed coil and smaller pickup coils(6) in the middle. It's powered from 6x 3000F ultra caps in series(500F) charged to 14vdc, currently dc pulsed with a irlz44n. The switching frequency, generated/adjustable by the Arduino, is around 630hz in this example, with two output coils in parallel going out to a 27watt Ultra-Tow led floodlight. This version has a poor output but testing continues.

[Farmhand]

What you say makes perfect sense.  If I rewrote it I would use the terms "inductive kickback pulse" or "flyback pulse" instead of BEMF in order to be clearer.  I will try to keep that in mind for the future.  I think the message still got through though because Tinman and Luc will discussing collecting pulses off of the motor from PWM excitation when the MOSFET turns off or possibly from the brushes themselves.  I assumed that was what Jimboot was referring to.

For what it's worth I normally use the term CEMF for what's going on in the armature.  That is also legitimately referred to as BEMF like you indicated.   And Farmhand also has a valid point in referring to the flyback pulse as forward EMF.

MileHigh

Well it goes without saying that when people refer to Forward emf as Back emf some will get confused by that, naturally. I sometimes refer to the "inductive kickback" as "Inductive energy release" which I think is valid also. I don't think "Inductive kick back" is a very technical or scientific term is it ? A better term would be returned emf.

Better in my opinion to refer to Counter emf as Cemf and the flyback as flyback or Returned emf or Inductive energy return or anything except Back emf. But if people want to confuse each other then we should just keep using Back emf to refer to Forward emf. 

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[Farmhand]

Thinking that we have open source rights on a suppressed or restricted technology is a pipe dream,

PERIOD

Applying for any sort of protection thru government agencies whether patents or other venues is like handing a man a stick to beat you with.

too many bruised inventors around....

Inventing things and patenting them is a legal way to make money and it works. But it is an act of asking for permission to prosecute others for using your inventions to make money without your permission, enforcing the patent is not an easy feat in itself. Nor should it be.

The way I see it if I don't ask then I won't get refused. I make it a rule to never ask the Authorities for permission to do something, then there is no refusal.

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[Dave45]

Well it goes without saying that when people refer to Forward emf as Back emf some will get confused by that, naturally. I sometimes refer to the "inductive kickback" as "Inductive energy release" which I think is valid also. I don't think "Inductive kick back" is a very technical or scientific term is it ? A better term would be returned emf.

Better in my opinion to refer to Counter emf as Cemf and the flyback as flyback or Returned emf or Inductive energy return or anything except Back emf. But if people want to confuse each other then we should just keep using Back emf to refer to Forward emf. 

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So dont you think Cemf turns into flyback when the magnetic field collapses.

Or am I missing something ,,, please explain

[Magluvin]

So dont you think Cemf turns into flyback when the magnetic field collapses.

Or am I missing something ,,, please explain

What he is saying is there is quite a bit of confusion of terms when it comes to this.

Reverse emf, counter emf, back emf, all seem to say that there is a reverse voltage coming from the coil when the 'forward' input is removed. Flyback is a whole other thing that has to do with cathode ray tubes, old tvs, oscilloscopes.

But in 'most' cases, when the input is removed from the coil, the field collapse causes current in the same direction through the coil as the current that was input.

Reverse emf typically is what happens when an inductor is being charged, building a field. The mag field of each winding in reference to every other winding induces the other windings to produce a reverse emf than the direction of the input emf. This is why it takes time for the coil to flow max current, because the input emf has to overcome the self induced emf during that time period. Once at max current flow and max field build, there is no more expanding flux to cut the windings thus zero reverse emf and full current is allowed to flow.

Now, I do have a theory that there can be a reverse output from the coil when the forward input is removed, but the switch would have to perfect or maybe near perfect in its ability to fully turn off in the presence of the high voltage developed by the collapse. I think that the coils self capacitance can cause the coil to oscillate, probably at very high freq, and when the field collapses and there is no path for the forward current to go when the perfect switch turns off, the voltage build on the coil end leads is basically being stored in the coils capacitance. When that voltage peaks, then current is reversed in the coil and able to say flow back to the source through say a diode in reverse across the switch.

There may be circumstances where a not so perfect switch could do the job.

In Circuit sim, you can do the experiment. On the first circuit shown when you bring up the applet, delete the cap, wire and resistor to the left of the inductor, then connect a diode across the switch with 2 wires. Also reduce the resistor below in the circuit to be more realistic to what the inductor might be in ohms.

The switch in this case is pretty much a perfect switch. When it is off, there is no hv from the coil collapse going anywhere, so the collapse current ends up after a half cycle of oscillation, going 'back' to the source through the diode in a reverse direction than what was input. So with the diode and a switch that can withstand the emf pressure of the coil collapse, I think there can be an actual reverse emf from the coil.

Possibly a Tesla rotary switch can disconnect fast enough to overcome field collapse voltage of a charged coil.

Mags