Dynamo design with regenerative back mmf

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Discussion Overview

The discussion revolves around a proposed dynamo design that incorporates regenerative back electromotive force (emf) and its implications on the behavior of a flywheel. Participants explore the dynamics of induced voltage, current flow, and the effects of magnetic fields during rotor operation, with a focus on theoretical and conceptual aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants describe the behavior of the dynamo design, noting that induced voltage occurs when the rotor approaches a magnet, but no current flows until the circuit is closed.
  • It is suggested that the induced current, according to Lenz's law, creates a magnetic north pole on the rotor side of the coil, which could potentially propel the rotor instead of braking it.
  • One participant questions the feasibility of the design, implying it may resemble a perpetual motion machine (PMM), while another clarifies that their intention was to explore the concept within the bounds of current physics.
  • Concerns are raised about the lack of current flow in an open circuit and the implications for energy storage and magnetic energy.
  • Another participant points out that at top dead center (TDC), the magnetic flux is at a maximum, leading to no induced emf or current at that moment.
  • Some participants discuss the concept of back mmf, suggesting it should oppose the motion of the magnet, potentially reducing its kinetic energy.
  • A reference to 'magneto ignition' is made, with a suggestion to study this concept for better understanding of the proposed machine.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of the dynamo design, particularly regarding the effects of induced emf and current flow. There is no consensus on whether the design can effectively propel the flywheel or if it behaves more like a braking mechanism.

Contextual Notes

Participants highlight limitations in understanding the behavior of the system, particularly regarding the conditions under which current flows and the implications of magnetic flux at TDC. The discussion remains open to interpretation and lacks definitive conclusions.

Narayanan KR
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disk rotor.jpg

In the above presented dynamo design, three snapshots taken during three instances during the rotor running.
In fig 1 the approaching magnet builds an induced voltage across the coil, however the circuit is still open, hence no current flows. In fig 2 when the rotor reaches TDC (top dead center) switch is closed leading to the flow of current into the load.
According to lenz law, this induced current flows so as to create north pole on the rotor facing side of the coil, and this will push the rotor away thus adding to the kinetic energy of the flywheel.
I wonder how the back mmf instead of braking the fly wheel, it pushes/propels the fly wheel, I hope you mates share your suggestions and critics on this idea, thank you.
 
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Narayanan KR said:
View attachment 199294
In the above presented dynamo design, three snapshots taken during three instances during the rotor running.
In fig 1 the approaching magnet builds an induced voltage across the coil, however the circuit is still open, hence no current flows. In fig 2 when the rotor reaches TDC (top dead center) switch is closed leading to the flow of current into the load.
According to lenz law, this induced current flows so as to create north pole on the rotor facing side of the coil, and this will push the rotor away thus adding to the kinetic energy of the flywheel.
I wonder how the back mmf instead of braking the fly wheel, it pushes/propels the fly wheel, I hope you mates share your suggestions and critics on this idea, thank you.
Since no current flows in the coil while the switch is open, there is no storage of magnetic energy. Were you hoping that you found a viable Perpetual Motion Machine (PMM)?

Nice avatar, BTW. :smile:
 
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berkeman said:
Since no current flows in the coil while the switch is open, there is no storage of magnetic energy. Were you hoping that you found a viable Perpetual Motion Machine (PMM)?

Nice avatar, BTW. :smile:
PMM?,I would never claim so. It was just a thought experiment performed within the rules of present physics and i was expecting an scientific explanation whether it works that way or not.
Even when coil is open it develops induced emf because of the changing magnetic flux linked to it, and the moment the load is connected across such emf current has to start flow.
 
Narayanan KR said:
PMM?,I would never claim so. It was just a thought experiment performed within the rules of present physics and i was expecting an scientific explanation whether it works that way or not.
Even when coil is open it develops induced emf because of the changing magnetic flux linked to it, and the moment the load is connected across such emf current has to start flow.
How does current flow through an open circuit? Mate in 2...
 
Narayanan KR said:
In fig 2 when the rotor reaches TDC (top dead center) switch is closed leading to the flow of current into the load.
At "TDC" the ##\Phi## is at a maximum so ##d\Phi/dt =0##. There is no EMF and no induced current.
 
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@Narayan KR
You're approaching a 'magneto ignition'. Study up on that subject and you'll be better able to work your hypothetical machine in your head.

When you can explain its "E-Gap" in a couple concise sentences , please do. It'll both cement the concept in your mind and help other students of magnetics who stumble across this thread.

Did you make those nice drawings ?

old jim
 
Narayanan KR said:
PMM?,I would never claim so. It was just a thought experiment performed within the rules of present physics and i was expecting an scientific explanation whether it works that way or not.
Even when coil is open it develops induced emf because of the changing magnetic flux linked to it, and the moment the load is connected across such emf current has to start flow.

As Dale pointed out, there is no emf and no current at TDC. But as the magnet moves away from TDC, there will be an induced emf and current in the coil. The coil mmf should try to "oppose the cause" of the induction i.e. it should try to stop the magnet from going away.
So the coil should attract the magnet and reduce its kinetic energy.
 
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jim hardy said:
@Narayan KR
You're approaching a 'magneto ignition'. Study up on that subject and you'll be better able to work your hypothetical machine in your head.

When you can explain its "E-Gap" in a couple concise sentences , please do. It'll both cement the concept in your mind and help other students of magnetics who stumble across this thread.

Did you make those nice drawings ?

old jim
Yes sir..I did those drawings on MS Paint, and 'magneto ignition'...i believe it will be interesting.
 

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