Anyone see an opportunity here to harness back EMF?
http://www.youtube.com/watch?v=tgX5cz1SMiw
A very concise, interesting device; worth spending two minutes of your time.
Enjoy.
Hi Matt Watts,
I captured the schematic from the video and edited a little to show one possibility to capture the voltage spikes across the driven pancake coil at any relay switch-off when the magnetic field collapses in the pancake. Perhaps a full wave rectifier across this coil would give more juice because it miay 'capture' some induction from the oscillating magnet too.
(Notice that in this latter case with the diode bridge across the coil, the input battery can also charge up the C puffer capacitor whenever the relay contacts are closed to energize the coil. This direct battery charge up to the C cap is not the case with the use of a single diode I indicated in the drawing.)
Some further thoughts:
I think a more refined capture of both the switch-off spikes and the induction from the magnet could be received in puffer capacitors when Skycollection used full wave diode bridges across the other three coils (and not across the driven coil as I suggested above). This is possible because the collapsing field from the controlled coil would surely induce pretty much the same 'juice' in all the other 3 coils which are in close magnetic coupling with the driven coil, the full wave diode bridges would capture them too, together with the induced 'juice' by the oscillating magnet.
To reduce input power draw, if he uses the old bipolar version, the 555 timer circuit has a CMOS version with very low power consumption and the relay could be replaced with a MOSFET to get rid of the relay coil current draw. The 555 could also be built with a variable duty cycle control too.
My suggestions above would improve the overall efficiency in an attempt to explore a possible output looping back to the input battery source, once the input and the received output powers become known with a reasonable accuracy. I am not saying the output will be higher than the input though... ;)
Gyula
Quote from: Matt Watts on 2014.12.03, 02:32:59
Anyone see an opportunity here to harness back EMF?
http://www.youtube.com/watch?v=tgX5cz1SMiw
If by "harness" you mean get more out of it than you put in, then no.
As long as that bouncing object is a hard ferromagnetic object (also known as a "permanent magnet") then there is no chance for this to behave outside of Faraday's law of induction.
Such a hard magnet has magnetic domains that are frozen in place and cannot move.
This makes the magnet behave like a spring, which is a very conservative device (100% efficient at best) - see the animation below.
(http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16008)
If however, the bouncing object was a piece of soft ferrite (or at least a laminated FeSi steel) in which domains can move freely, then there would be some hope for this device using a Modus Operandi described
in this post (http://www.overunityresearch.com/index.php?topic=2684.msg43698#msg43698) (follow the "
point C" link in that post, too)
(http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16010)
The above is an simplified conceptual schematic of the piston motor with a soft ferromagnetic bouncer and energy recovery.
The switches S1 and S2 should be low R
DS(ON) MOSFET switches of course and they never should be ON at the same time.
@Matt Watts
Thanks for that post. That pancake coil and magnet is very similar to what I recommended to Tommy Reed, See diagram here;
http://www.overunityresearch.com/index.php?topic=2684.msg43396#msg43396
He would have had 8 of those pistons flying through multiple pancakes, not simply like in that video where the magnet acts only on one side. All with no cogging. All he had to do is use his flyhweel like a drive wheel with a few magnets on the edge and drive coils and he could have harnessed the bemf from the drive coils to reduce input and he could have eliminated the 8 piston control.
wattsup
Quote from: verpies on 2015.01.13, 00:23:39
If by "harness" you mean get more out of it than you put in, then no.
As long as that bouncing object is a hard ferromagnetic object (also known as a "permanent magnet") then there is no chance for this to behave outside of Faraday's law of induction.
Such a hard magnet has magnetic domains that are frozen in place and cannot move.
This makes the magnet behave like a spring, which is a very conservative device (100% efficient at best) - see the animation below.
What people don't take into consideration is the phase delay that can occur in the magnetic domain. IOW, with the right magnetic conditions it is possible to get almost a 90 degree phase shift between the applied mmf from the moving magnet (as determined by its instantaneous position) and the flux in the coil. That produces an enormous armature reaction where our induction laws appear to go out of the window. Whereas in normal generators the Lenz flux coming from the current induced into the coil appears at a phase such that the moving or rotating magnet sees a drag force, and that drag force equates to the power being supplied to the load, when you get this huge armature reaction that equality no longer applies. Power to the load no longer comes directly from the drive shaft, it comes from the electron spins within the PM. In its simplest form of a magnet rotating within a coil, maximum voltage hence maximum load current occurs not when the magnet axis is at right angles to the coil axis, but when the magnet axis is parallel to the coil axis. Unfortunately it is virtually impossible to achieve this magnetic domain phase shift using air coils (although when room temp superconductors become available the situation is much easier). The only possibility I can see is for a coil wound on a C core that has a very small air gap, like just a 1mm gap. Then it is possible to load that coil with a very low value resistance so that the L/R time constant is long compared to the time for 1 cycle at the operating frequency, while at the same time the coil resistance is even lower and does not consume much power. Then the magnet has to be a very thin disc (like 0.5 mm thick magnetized across its thickness) that passes through that gap. This form of generator offers OU operation, but I am not aware of anyone trying to make one.
Quote from: Smudge on 2015.01.13, 16:57:45
What people don't take into consideration is the phase delay that can occur in the magnetic domain.
Yes, but that is possible only in soft ferro/ferrimagnetic materials. Not in hard ones - like permanent magnets.
See this video for an illustration of the magnetic domain disturbance propagating in a ferromagnetic material.
http://youtu.be/U9lsaGtRBGc
Quote from: Smudge on 2015.01.13, 16:57:45
IOW, with the right magnetic conditions it is possible to get almost a 90 degree phase shift between the applied mmf from the moving magnet (as determined by its instantaneous position) and the flux in the coil.
That is a shortsighted statement.
Yes, a delay can be introduced before a magnetic pulse gets to a coil, but a coil will still react instantaneously when this pulse gets to it.
You could introduce even a longer delay with a slinky (a long spring) with a hard permanent magnet attached to one end of it and near a coi and the other end pulsed mechanicallyl. Like this:
Pulse ---> |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/| N--------S Coil
Do you think that the delay offered by a slinky would allow the pulse to induce more energy in the coil, than pulsing the magnet directly?
C'mon think!
[/quote]
Hi All,
I like this idea of pulsing air core, I worked with different design in the past.
I would like to add that this basic design I put up does allow for this type of pulse design.
Even if I used a magnet linear core that moves through the air core, this will generate bemf and also allow a greater return of energy that was used due to the fact it's a motor generator design.
This is my basic desiign.
https://www.youtube.com/watch?v=p0YU4x3TEeQ
Many minds are better then one, I respect this very fact!
I will offer my basic skills of building prototypes to this interesting air core piston project.
In other words, I can be a team player, all I ask is for integrity that make us all respected.
Let's get started!
Tom
Tom
Verpies has some wonderful paths to explore.....
A very kind gesture and a wonderful opportunity for this community.
thank you for stepping up.
respectfully
Chet
You are making A HUGE CONCEPTUAL ERROR by thinking that a faster change of magnetic flux (dΦ/dt) will induce more current or energy in a coil.
Faster dΦ/dt causes larger EMF but not larger current (nor energy) to be induced in a coil. This energy depends only on change of flux (ΔΦ) that penetrates the coil.
The induced energy does not depend on how quickly the magnetic field changes! It does not depend on the flux density (B) either ...nor on its rate of change (dB/dt).
A Whitworh mechanism driving a magnet, as depicted on diagrams shown below, will not induce different current (nor energy) in the coil on the forward and back stroke.
Somebody on overunity.com even made an experiment that proved that with a superconducting loop. See here (http://overunity.com/14443/quantum-energy-generator-qeg-open-sourced-by-hopegirl/msg402619/#msg402619).
(http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16040)
(http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16042)
(http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16008)
Hi All,
This is my basic build I did today, still have to add the electronics to drive this simple pulse motor.
https://www.youtube.com/watch?v=gKSrQHgVujU
Tom
This motor will induce more electric power in the coil on the forward stroke than on the backward stroke, but not more energy.
If you are after asymmetrical power pulses, then it is easier to charge a motor capacitor with 1W for 10s and then suddenly short it with a screwdriver. You can probably get 800kW for 1μs this way.
Hi Verpies,
Yeah I agree, but lets not forget the BEMF when the forward coil is pulsed.
Tom
Hi Tommey,
It does not matter when the EMF does not cause a current flow.
In an ideal shorted coil the induced voltage is a meaningless quantity anyway - it cannot be even accessed nor measured nor used in the Ohm's law without causing division by zero.
Coils are inherently current devices ...and capacitor are voltage devices.
Thus the electric energetics of coils should be judged by current
...and the energetics of capacitors - by voltage.
Maybe a multi cylinder setup of my engine design Tom?.
https://www.youtube.com/watch?v=Z4VJG8-9izQ
Ho Tinman,
I don't agree on this noble gas engine, IC engine works off heat generated by a fuel.
I would just look at a plasma pulse to generate heat to drive a engine then a foolish noble gas theory that won't have enough heat to do nothing at all.
I have could design a plasma engine, but just have other things to do like stay warm this winter...
Tom
Quote from: TinMan
Maybe a multi cylinder setup of my engine design Tom?.
https://www.youtube.com/watch?v=Z4VJG8-9izQ
That's quite an innovative approach TinMan!
Is your magnetic piston operating by attraction or
repulsion?
Quote from: muDped on 2015.01.17, 00:35:21
That's quite an innovative approach TinMan!
Yes indeed!
What is that magic clutch gizmo again? I got to get me one of those. So cool how you solved the angular misplacement problem of a typical ICE.
Quote from: verpies on 2015.01.13, 18:02:33
Yes, but that is possible only in soft ferro/ferrimagnetic materials. Not in hard ones - like permanent magnets.
What I am getting at is a generally unrecognized phase delay that occurs in the magnetic domain. I am not talking about a propagation time delay such as is known to occur in soft ferromagnetic materials. Let me explain further. The voltage induced into a coil is proportional to the time rate of change of the flux within the coil. Some flux can come from say a moving magnet, but there is also a component coming from any current flowing in the coil, even if that current has been induced by the moving magnet. So when we wish to accurately calculate the voltage applied to a load (and the current flowing in that load) we have to take account of the effect of the coil's inductance that adds its own self-flux to the flux coming from the magnet. Under normal operating conditions that self-flux is usually negligible so we ignore it. But we can create the condition where the self-flux is dominant. If the flux from the magnet follows a sine wave then that condition is met when the load resistor is small compared to the reactance of the coil's self-inductance. And under those conditions you get the coil current shifted by almost 90 degrees from where it would be normally. That modifies considerably the torque waveform on the drive shaft, and it also creates interesting power flows to and from the atomic dipoles within the permanent magnet.
The attached pdf was written some years ago and illustrates the phasor diagram for the applied flux from the moving magnet, the self-flux from the coil current (called Lenz flux) and the resulting flux that delivers the induced voltage. The paper also looks into the power waveforms and energy flows (a) at the mechanical input shaft and (b) at the electrical load where at large phase angles the power to the load is not delivered coincidently with power taken from the shaft. Over parts of the cycle the shaft torque is negative, but note this is not the usual cogging torque associated with magnets moving relative to some ferromagnetic material. This analysis assumed a magnet rotating within an air cored coil (but perhaps rotating at impossible speeds). So the cogging torques are all self imposed by the load current itself. If nothing else, this paper illustrates that there are things going on in the magnetic domain that are usually unknown or simply ignored. And the reports of OU eddy current heaters where magnets move in close proximity to a highly conductive disc, and where that phase shift becomes a reality, support the view that this could be a route to OU.
Smudge
Quote from: Matt Watts on 2015.01.17, 07:59:24
Yes indeed!
What is that magic clutch gizmo again? I got to get me one of those. So cool how you solved the angular misplacement problem of a typical ICE.
Dear Matt.
Sprag clutch bearing..... Like these.......
https://www.google.co.uk/search?q=sprag+clutch+bearing&newwindow=1&source=univ&tbm=shop&tbo=u&sa=X&ei=QaO6VIT5DIO27gbXrIC4CA&ved=0CCIQsxg&biw=1920&bih=943
I am not certain about this but may have been invented by Otto for his early atmospheric engine you commented upon last year.
Brad may have had a good reason for using this idea but for me I would have worked out the full stroke suitable for a standard crank and counter balance because there is energy gained from the mass of the magnetic piston on the down stroke.
Cheers Grum.
Quote from: Smudge on 2015.01.17, 16:04:07
What I am getting at is a generally unrecognized phase delay that occurs in the magnetic domain.
Just let me verify that you really mean "domain" and not "domains".
Quote from: Smudge on 2015.01.17, 16:04:07
The voltage induced into a coil is proportional to the time rate of change of the flux within the coil.
Yes, but I do not like your terminology.
The voltage is induced across the coil - not "into" a coil. The only electric thing flowing in the windings of a coil is current.
Quote from: Smudge on 2015.01.17, 16:04:07
Some flux can come from say a moving magnet, but there is also a component coming from any current flowing in the coil, even if that current has been induced by the moving magnet.
Yes, and these two fluxes are exactly equal and opposite through a surface spanning the hole of an ideal shorted air coil.
Quote from: Smudge on 2015.01.17, 16:04:07
So when we wish to accurately calculate the voltage applied to a load (and the current flowing in that load) we have to take account of the effect of the coil's inductance that adds its own self-flux to the flux coming from the magnet. Under normal operating conditions that self-flux is usually negligible so we ignore it.
I don't know what you mean by "normal operating conditions".
To me a normal operating condition for a coil is a condition that maximizes the flux current flowing through it, because a coil inherently is a current device and any resistance to that current is just a sink to the energy stored in that coil.
Quote from: Smudge on 2015.01.17, 16:04:07
But we can create the condition where the self-flux is dominant.
No, the induced current and flux that it creates is never larger than the externally applied flux, (when if we start from zero).
The word "dominant" implies "larger than".
Quote from: Smudge on 2015.01.17, 16:04:07
If the flux from the magnet follows a sine wave then that condition is met when the load resistor is small compared to the reactance of the coil's self-inductance.
Inductive reactance implies a frequency domain analysis. I will not analyze the system this way because in such analysis the starting conditions are undefined.
If you want to continue this analysis with me you'll have to do a full transient state analysis - in other words: you must start from zero current and zero flux and zero force.
Quote from: Smudge on 2015.01.17, 16:04:07
And under those conditions you get the coil current shifted by almost 90 degrees from where it would be normally.
"Normally" compared to what?
Quote from: Smudge on 2015.01.17, 16:04:07
That modifies considerably the torque waveform on the drive shaft,
But torque is not proportional to the flux - it is proportional to the gradient of the magnetic flux density. Thus you cannot assume that the torque is in phase with the flux magnitude.
Quote from: Smudge on 2015.01.17, 16:04:07
The attached pdf was written some years ago and illustrates the phasor diagram for the applied flux from the moving magnet, the self-flux from the coil current (called Lenz flux)
I know Cyril Smith's work.
Quote from: Smudge on 2015.01.17, 16:04:07
and the resulting flux that delivers the induced voltage.
Flux does not deliver voltage. Flux magnitude is not even proportional to the voltage. The rate of change of flux is.
The only thing that is proportional to the flux magnitude is the induced current in an ideal shorted coil (if you start from zero).
Quote from: Smudge on 2015.01.17, 16:04:07
The paper also looks into the power waveforms and energy flows (a) at the mechanical input shaft and (b) at the electrical load where at large phase angles the power to the load is not delivered coincidentally with power taken from the shaft.
The mechanical input (torque) is not proportional to the magnitude of flux. Flux does not cause any mechanical attraction - it's gradient does. It's not surprising that the torque is not in phase with the flux.
Quote from: Smudge on 2015.01.17, 16:04:07
Over parts of the cycle the shaft torque is negative, but note this is not the usual cogging torque associated with magnets moving relative to some ferromagnetic material.
If you mean the negative torque on a magnet moving relative to a coil, then this is nothing unusual. Just take a look at
my animation (http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16008) of the bouncing magnet over an ideal shorted coil. The force acts on it in both directions periodically.
Quote from: verpies on 2015.01.17, 21:18:01
I know Cyril Smith's work.
Hopefully you know that you are talking with him too.
He's got some good stuff that has allowed me to visualize concepts I thought were far from my abilities.
Something I would really like one of you guys to explain, is how the Lenz flux from a loaded secondary winding in a transformer changes the phase angle between voltage and current in the primary. I'd really like to understand the mechanics of this. I know it does it, but I do not fully understand why and have little appreciation as to how.
Thanks much,
M@
Quote from: Matt Watts on 2015.01.18, 00:38:05
Hopefully you know that you are talking with him too.
I had no idea. The funny thing is that my father had known him from the Vortex-L list and OUbuilders list.
Quote from: Matt Watts on 2015.01.18, 00:38:05
Something I would really like one of you guys to explain, is how the Lenz flux from a loaded secondary winding in a transformer changes the phase angle between voltage and current in the primary.
That's a good question. If the flux generated by the primary is taken as a given (as input data to a problem) then this makes it equivalent to the problem outlined in Cyril's paper. I will answer that because it will also be relevant to his analysis.
But first of all: do do I have to explain why the phase angle in a
single coil (in a series RL circuit) that is driven by a sinewave voltage source is equal to tan
-1(R/(L*2πf)) ?
In other words: Do I have to explain why the phase angle of a
single coil (in a series RL circuit) depends on the frequency, resistance and inductance ?
Quote from: verpies on 2015.01.18, 02:34:09
But first of all: do do I have to explain why the phase angle in a single coil (in a series RL circuit) that is driven by a sinewave voltage source is equal to tan-1(R/(L*2πf)) ?
In other words: Do I have to explain why the phase angle of a single coil (in a series RL circuit) depends on the frequency, resistance and inductance ?
Give me a few days to digest this: https://en.wikipedia.org/wiki/RL_circuit
Maybe I can answer it for myself.
Quote from: verpies on 2015.01.17, 21:18:01
Just let me verify that you really mean "domain" and not "domains".
Yes, I do not mean "domains", I am talking about the magnetic "domain" as compared to the electric "domain". In the electric "domain" we generally deal with voltage and current where the current is confined to flow along and within cylindrical conductors thus creating an electric circuit. We also take account of effects due to interactions with electric and magnetic fields that appear outside conductors by having components such as capacitors and inductors. We have well known means for analyzing such circuits in either the frequency domain or the time domain.
In the magnetic "domain" we deal with mmf and flux where the flux is generally (but not always) confined to flow along and within cylindrical core material thus creating a magnetic circuit. However we are not taught how to perform dynamic analysis of this magnetic circuit. At best we have a series of magnetic "resistors" (actually magnetic reluctance) but we do not have other magnetic components that take account of things external to the core material (such as your ideal shorted coil). In the absence of such components we cannot perform dynamic analysis of that magnetic circuit. As a matter of interest your ideal shorted coil appears as a magnetic "inductance" Lm (obeying mmf = -Lm*dPhi/dt) of infinite value, hence ensuring that flux Phi through the coil is zero. A coil connected to a load resistor R appears as a magnetic inductance of value Lm=(N^2)/R where N is the number of turns. Having the external (electrical) circuit expressed as a magnetic component allows us to discover phase shifts occurring in the magnetic domain that are otherwise hidden from us.
QuoteYes, but I do not like your terminology.
The voltage is induced across the coil - not "into" a coil. The only electric thing flowing in the windings of a coil is current.
I can't argue with that, but in defence of my terminology the voltage appearing across the coil is the line integral (along the conductor) of the electric field E created by the changing flux (from E=-dA/dt) and that induction appears all along the wire. Perhaps I should have said voltage induced into the conductor.
QuoteYes, and these two fluxes are exactly equal and opposite through a surface spanning the hole of an ideal shorted air coil.
So the net flux through the coil is zero, the classical superconducting loop expelling flux. And this is obvious in my phasor diagram where the operating point is to the left of the semi-circle. But we are not talking about an ideal shorted coil, we are dealing with a real load resistor, albeit of low value.
QuoteI don't know what you mean by "normal operating conditions".
To me a normal operating condition for a coil is a condition that maximizes the flux current flowing through it, because a coil inherently is a current device and any resistance to that current is just a sink to the energy stored in that coil.
I am talking about a PM generator where practical limitations of rotor speed keep the frequency low so normally the load resistor is of value greater than the coil reactance.
QuoteNo, the induced current and flux that it creates is never larger than the externally applied flux, (when if we start from zero).
The word "dominant" implies "larger than".
And I meant the induced current and flux that it creates is larger than the resultant flux through the coil, in other words close to the situation for your ideal shorted coil where the resultant flux is zero.
QuoteInductive reactance implies a frequency domain analysis. I will not analyze the system this way because in such analysis the starting conditions are undefined.
If you want to continue this analysis with me you'll have to do a full transient state analysis - in other words: you must start from zero current and zero flux and zero force.
Could do that but ultimately the system will settle down to the situation as described.
Quote"Normally" compared to what?
Again I am talking about a PM generator which in its simplest form could be a magnet rotating within a coil. Normally the peak induced voltage hence also coil current occurs when the magnet axis is at 90 degrees to the coil axis. This is also the position where that same coil current creates maximum torque on the magnet. When the coil current is shifted by almost 90 degrees peak current then occurs at a magnet position where torque is near zero.
QuoteBut torque is not proportional to the flux - it is proportional to the gradient of the magnetic flux density. Thus you cannot assume that the torque is in phase with the flux magnitude.
Linear force on a magnetic dipole is proportional to the gradient of the flux density. The gradient does not appear in the torque formula, see below.
QuoteI know Cyril Smith's work.
That's me!
QuoteThe mechanical input (torque) is not proportional to the magnitude of flux. Flux does not cause any mechanical attraction - it's gradient does. It's not surprising that the torque is not in phase with the flux.
You are wrong there. A magnetic dipole of moment mu in a field B exhibits a torque T of magnitude T = mu*B*sin(theta) where theta is the angle between the dipole axis and the field B. I think you have confused this with the linear force F on a dipole that has a magnitude of F = mu*(dB/dx)*cos(theta) where B lies along the x axis.
QuoteIf you mean the negative torque on a magnet moving relative to a coil, then this is nothing unusual. Just take a look at my animation (http://www.overunityresearch.com/index.php?action=dlattach;topic=2701.0;attach=16008) of the bouncing magnet over an ideal shorted coil. The force acts on it in both directions periodically.
Clever animation. But the real issue here is whether a magnet bouncing over a coil that is not quite shorted has any potential for OU operation, that electrical output can exceed mechanical input. You have not stated whether you agree with the magnetic domain phase shifts as indicated by my phasor diagram (although your ideal shorted coil analysis where the self-flux exactly cancels the applied flux would suggest that you do agree). My personal view is that OU operation is possible but achieving it with moving parts is difficult.
Smudge
Quote from: verpies on 2015.01.18, 02:34:09
I had no idea. The funny thing is that my father had known him from the Vortex-L list and OUbuilders list.
Yes I was on Dave Squires's OUbuilders forum. As a matter of interest who is your father?
Smudge (aka Cyril Smith)
Quote from: Matt Watts on 2015.01.18, 00:38:05
Something I would really like one of you guys to explain, is how the Lenz flux from a loaded secondary winding in a transformer changes the phase angle between voltage and current in the primary. I'd really like to understand the mechanics of this. I know it does it, but I do not fully understand why and have little appreciation as to how.
Thanks much,
M@
Maybe my paper on transformers could help.
Smudge
Quote from: Smudge on 2015.01.18, 12:00:06
Yes, I do not mean "domains", I am talking about the magnetic "domain" as compared to the electric "domain".
I'm glad and that's clear now.
BTW: I dislike analyzing inductors in the electric domain because they are predominantly current/flux devices at low frequencies.
However I like to analyze capacitors in the electric domain.
Quote from: Smudge on 2015.01.18, 12:00:06
So the net flux through the coil is zero, the classical superconducting loop expelling flux.
If we begin by shorting such coil with zero flux penetrating it, then yes.
But it is possible to start with non-zero flux and then such coil will freeze this flux. This flux can do real work, e.g. attract soft iron piston from afar.
Quote from: Smudge on 2015.01.18, 12:00:06
But we are not talking about an ideal shorted coil, we are dealing with a real load resistor, albeit of low value.
I view the resistance as inserting an imperfection into the coil. The moment the resistance is introduced, the energy stored in the coil starts to leak out.
It is like putting a hole in the bottom of the bucket and poring water into it. If you pour in more than leaks out through the hole you get the illusion that the water level depends on the speed with which new water is arriving. Without the hole, the level depends merely on the quantity of water arriving.
This was an analogy to di/dt and Δi
Quote from: Smudge on 2015.01.18, 12:00:06
And I meant the induced current and flux that it creates is larger than the resultant flux through the coil, in other words close to the situation for your ideal shorted coil where the resultant flux is zero.
That's hard to understand without the words "absolute value" while disregarding signs or direction of the fluxes ...but now I know what you mean.
Quote from: Smudge on 2015.01.18, 12:00:06
Again I am talking about a PM generator which in its simplest form could be a magnet rotating within a coil.
Your paper did not have a diagram of that rotating arrangement and this is a "piston project" thread that implies a reciprocating linear motion and linear forces.
Quote from: Smudge on 2015.01.18, 12:00:06
Normally the peak induced voltage hence also coil current occurs when the magnet axis is at 90 degrees to the coil axis. This is also the position where that same coil current creates maximum torque on the magnet.
With a magnet rotating inside the coil like in a Joseph Newman arrangement, yes.
Quote from: Smudge on 2015.01.18, 12:00:06
When the coil current is shifted by almost 90 degrees, peak current then occurs at a magnet position where torque is near zero.
Do you mean the coil's current shifted 90º in reference to the magnet's angle or in reference to something else?
Quote from: Smudge on 2015.01.18, 12:00:06
Linear force on a magnetic dipole is proportional to the gradient of the flux density. The gradient does not appear in the torque formula, see below.
<snip>
A magnetic dipole of moment mu in a field B exhibits a torque T of magnitude T = mu*B*sin(theta) where theta is the angle between the dipole axis and the field B. I think you have confused this with the linear force F on a dipole that has a magnitude of F = mu*(dB/dx)*cos(theta) where B lies along the x axis.
With a magnet rotating inside the coil, your are correct about the torque. I thought you were referring to a linear force because this is a reciprocating piston thread.
Quote from: Smudge on 2015.01.18, 12:00:06
Clever animation. But the real issue here is whether a magnet bouncing over a coil that is not quite shorted has any potential for OU operation, that electrical output can exceed mechanical input. You have not stated whether you agree with the magnetic domain phase shifts as indicated by my phasor diagram (although your ideal shorted coil analysis where the self-flux exactly cancels the applied flux would suggest that you do agree).
I don't know yet. We have to discuss it more.
Please elaborate on your statement in the paper:
"
Because the current creating the Lenz reaction is at 90° phase with respect to the resultant flux in the coil..."
First of all, I'd like to confirm, that you are referring to a temporal phase shift (not a spatial phase shift).
IMO any resistance in the coil's circuit is just an energy leak.
How can an energy that is leaking out make more energy?
But it is true that in the frequency domain the phase shift in a series RL circuit is dependent on L, f and R.
The currents in the power supply, in the resistance and in the inductor are always in phase, because it is a series circuit.
We have to be clear what phase shift we are discussing in an RL circuit, e.g. between:
1) Driving voltage and inductor's current
2) Driving voltage and inductor's voltage
3) Driving voltage and resistor's current
4) Driving voltage and resistor's voltage
5) Resistor's voltage and inductor's current
6) Resistor's voltage and inductor's voltage
Quote from: verpies on 2015.01.18, 18:43:44
If we begin by shorting such coil with zero flux penetrating it, then yes.
But it is possible to start with non-zero flux and then such coil will freeze this flux. This flux can do real work, e.g. attract soft iron piston from afar.
Agreed and that is then a superconducting magnet as used in MRI machines. But note that such a magnet has a different dynamic operating regime than a conventional PM because of that flux freeze, the flux remains constant while the soft iron is attracted. In a PM that is not the case.
QuoteYour paper did not have a diagram of that rotating arrangement and this is a "piston project" thread that implies a reciprocating linear motion and linear forces.
I see where the confusion arises, I should have made it clear the paper was dealing with rotation. Sorry about that.
QuoteWith a magnet rotating inside the coil like in a Joseph Newman arrangement, yes.
Exactly so.
QuoteDo you mean the coil's current shifted 90º in reference to the magnet's angle or in reference to something else?
Since the paper dealt with rotation creating sine waves there is a direct correlation between magnet angles and electrical phase angles. I tried to imply that in the normal operating regime peak coil current occurs when the magnet axis is at right angles to the coil axis, but under these abnormal conditions peak coil current is shifted by almost 90 degrees (electrically) so it occurs when the magnet axis is aligned with the coil axis.
QuoteI don't know yet. We have to discuss it more.
Please elaborate on your statement in the paper:
"Because the current creating the Lenz reaction is at 90° phase with respect to the resultant flux in the coil..."
First of all, I'd like to confirm, that you are referring to a temporal phase shift (not a spatial phase shift).
Well as I said above it is actually both, the L/R time constant creates a temporal phase shift which correlates with a spatial one.
QuoteIMO any resistance in the coil's circuit is just an energy leak.
How can an energy that is leaking out make more energy?
You could ask a similar question with regard to conventional transformers, how does energy leaking out of the secondary cause the primary to absorb more energy from the input? The flux through the secondary is essentially the same whether the secondary is open circuit or loaded, so what feeds back to the primary to make it draw more power? I think that is also Matt Watts dilemma. The answer is not via flux feedback, but via mmf feedback. So energy leaking out of a coil can influence the driving system, and the aim of us OU engineers is to discover how that feedback can extract energy from some other domain (like space or the quantum world), rather than from the transformer primary input or the shaft input of a generator. Personally I think a link to quantum world exists via the atomic magnetic dipoles in soft or hard ferromagnetic materials. I know that such dipoles deliver and extract energy all the time in electrical machines but this is never taken into account.
QuoteBut it is true that in the frequency domain the phase shift in a series RL circuit is dependent on L, f and R.
The currents in the power supply, in the resistance and in the inductor are always in phase, because it is a series circuit.
We have to be clear what phase shift we are discussing in an RL circuit, e.g. between:
1) Driving voltage and inductor's current
2) Driving voltage and inductor's voltage
3) Driving voltage and resistor's current
4) Driving voltage and resistor's voltage
5) Resistor's voltage and inductor's current
6) Resistor's voltage and inductor's voltage
Those are all in the temporal domain assuming an electrical input from a power supply. We are dealing with an input flux coming from a moving source, so we need other links to that flux and the movement. I tried to simplify things by using rotation and sine waves. But I agree we need to spell out what we mean. I'll try to write a paper on the reciprocating version.
Smudge
Quote from: Smudge on 2015.01.19, 16:40:46
Agreed and that is then a superconducting magnet as used in MRI machines. But note that such a magnet has a different dynamic operating regime than a conventional PM because of that flux freeze, the flux remains constant while the soft iron is attracted. In a PM that is not the case.
Yes and I always missed a physical law that would state that "flux freeze" in an ideal inductor directly. We have a Lenz's law which only states the
direction of the induced current and flux, but we have no law that directly states their
magnitude.
In other words: Lenz's law is a qualitative law but we need a quantitative one.
This quantitative law for ideal inductors would eliminate so much confusion about induction.
For example the Faraday's law for non-ideal inductors could be derived from it, by modeling the series resistance in an inductor as an energy leak that dissipates the induced current.
It then becomes immediately obvious that the current is proportional to the change of flux (ΔΦ) in an ideal coil and to the rate of change of flux (dΦ/dt) in a "leaky coil".
If the driving waveform is sinusoidal then the 90º phase shift in a "leaky coil" becomes immediately apparent because the derivative of the sine is a cosine.
This is analogous to the voltage across a capacitor: For an ideal capacitor the voltage is proportional to the total amount of electric charge that has arrived from the beginning ...but for a non-ideal capacitor (with a parallel resistance which leaks its energy) the voltage is proportional to the rate of change of charge.
This is a very intuitive approach, too because all that is needed to understand it is the effect that a leak has on stored quantity.
At this time I usually like to use an analogy of a leaky bucket with some water being poured into it at a different rates.
Quote from: Smudge on 2015.01.19, 16:40:46
Since the paper dealt with rotation creating sine waves there is a direct correlation between magnet angles and electrical phase angles. I tried to imply that in the normal operating regime peak coil current occurs when the magnet axis is at right angles to the coil axis,
In that case would use the "quantitative Lenz's law, stipulated above (for the lack of a better name) to notice that in a non-ideal coil the energy leaks out so quickly that the current in the coil (which always is an indicator of how much energy is stored in the coil) is proportional to the rate of change of flux (dΦ/dt) and this flux changes the quickest when that rotating magnet's magnetization axis is perpendicular to the coil's axis (functions Φ(t) and Φ(α) cross zero then).
Quote from: Smudge on 2015.01.19, 16:40:46
under these abnormal conditions peak coil current is shifted by almost 90 degrees (electrically) so it occurs when the magnet axis is aligned with the coil axis.
I see it like this: As the coil becomes more and more ideal (less and less energy leak) then the current starts being less proportional to the rate of change of flux and more proportional to the change of flux (less to dΦ/dt and more to ΔΦ). In the limiting case (when the resistance disappears completerly) the "quantitative Lenz's law" takes full effect and "flux freezing" appears which makes the induced current proportional only to the change of flux (ΔΦ).
So in the case of your rotary generator with an ideal shorted coil, the induced current is just proportional to the flux component parallel to the coil's axis.
Here, I probably should write some kind of resistance dependent "blending function" for the induced current, that increases the contribution of dΦ/dt and decreases the contribution of ΔΦ as the resistance increases. But I'm too sleepy for that now.
Quote from: Smudge on 2015.01.19, 16:40:46
You could ask a similar question with regard to conventional transformers, how does energy leaking out of the secondary cause the primary to absorb more energy from the input?
But that would be a different question, because this one is about energy input (absorption) and my question was about energy output.