Can cogging in permanent magnet motors be utilized for rotational movement?

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Discussion Overview

The discussion revolves around the concept of utilizing cogging in permanent magnet motors for rotational movement. Participants explore the potential for creating rotational motion using magnetic forces, examining various systems and configurations that could achieve this effect.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose using a rotating disk to facilitate the desired rotational movement of a particle influenced by magnets.
  • One participant suggests the idea of a slave magnetic dipole rotating under the influence of a master magnetic dipole, expressing uncertainty about the stability of such a system.
  • Another participant describes a potential system involving two rotating pendulums on a ball-bearing tracked ring, though they express confusion about the original post's intent.
  • There is mention of a bar magnet orbiting the Earth in a polar orbit as a hypothetical system to consider.
  • One participant notes that small permanent magnet motors exhibit cogging, which could align with the original inquiry about rotational movement, albeit over small angles.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific system or method for achieving the desired rotational movement. Multiple competing views and ideas are presented, with some participants expressing confusion or uncertainty about the original concept.

Contextual Notes

Participants outline various systems and configurations without providing definitive solutions or established methods. The discussion includes speculative ideas and hypothetical scenarios that remain unresolved.

physea
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Hello

With a normal magnet, we use energy to position a particle away from the magnet and then the magnet does work and moves it close to the magnet.

Is there any way to have such movement being rotational? Ie to uae energy to move a particle or point clockwise and then the magnet will move it anticlockwise?
 
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You can place it on a rotating disk.
 
SemM said:
You can place it on a rotating disk.

What do you mean??
 
I am not sure how you describe this system, maybe you should upload a sketch of what you are trying to explain.
 
SemM said:
You can place it on a rotating disk.
Like this:

http://syberspace.typepad.com/.a/6a00d8341e2e5053ef01156f08bf51970c-500wi
6a00d8341e2e5053ef01156f08bf51970c-500wi.jpg
 

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physea said:
Hello

With a normal magnet, we use energy to position a particle away from the magnet and then the magnet does work and moves it close to the magnet.

Is there any way to have such movement being rotational? Ie to uae energy to move a particle or point clockwise and then the magnet will move it anticlockwise?
There is one system where I can see the slave magnetic dipole rotating under the influence of a master magnetic dipole, but I'm not sure it is a stable system. Can you suggest some of the systems you have been thinking about?
 
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berkeman said:
There is one system where I can see the slave magnetic dipole rotating under the influence of a master magnetic dipole, but I'm not sure it is a stable system. Can you suggest some of the systems you have been thinking about?

Unfortunately I am only outlining my requirements, I am not aware of any systems.
 
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physea said:
Unfortunately I am only outlining my requirements, I am not aware of any systems.

You can use two rotating pendulums, bound to a ballbearing-tracked ring, where the magnet glides on. one with an inferior radius to the other. But I still don't get your original post. The pendulum like structure rotates about the center, instead of undulating back and forward, and hopefully the magnetic impulse each time they meet through rotating on the rings, they propagate one another to do another revolution.
 
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  • #10
physea said:
Hello

With a normal magnet, we use energy to position a particle away from the magnet and then the magnet does work and moves it close to the magnet.

Is there any way to have such movement being rotational? Ie to uae energy to move a particle or point clockwise and then the magnet will move it anticlockwise?

It sounds like the first few seconds of this video.


This video is even better. It uses a magnet and a compass.
 
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  • #11
I think what he means is that he wants a particle to rotate along a circumference rather than move directly closer to the magnet. If this is the case, I assume you could have a dipole on rotating disc and a counteracting dipole on the opposite side of the particle to make sure the particle follows a circumferential path and doesn't curve into the dipole.
 
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  • #13
Most small cheap permanent magnet motors exhibit an effect normally called cogging. If you try and rotate them by hand they don't turn smoothly but have a preference for stopping in certain position. This appears to meet the requirement of the OP (although it only works over small angles).
 

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