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Author Topic: Electromagnetic monopole - sort of?  (Read 3891 times)

Low-Q

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Electromagnetic monopole - sort of?
« on: September 28, 2017, 12:00:45 AM »
I plan to surround a PM with a coil where the windings goes only in one direction. The part of the coil I want to use is a torodial-looking coil where the windings goes only in one direction. The other direction is outside it.


Inside this coil, or more correctly right above, I place a free rotating neo-magnet. Like a homopolar motor style.
I want the magnetic field from the magnet to cross the windings only once, or mostly once.


The last experiment with the harp shaped coil did not work, because of one, possibly two things:
1. The field crossed the coil twice.
2. There is no field gradient along the magnets circumference.


In the image below, one side of the coil is solely one directionally winded. The other side has the windings exit as well as one directionally winding.


I will print out the part that holds the coil, and also a part where I can support the right hand side of the coil - not showing in the image.
I must possibly shield the exit/entrance-part of the coil, or use an iron/ferrite cylinder that surrounds the "monopolar" part of the coil. But gather all entrance and exit wires into one bundle of litz-wire looking wire, so all the wires that is not vertical, follows a circle - like you see on the left hand side of the model.


This test will probably not work as a homopolar brushless motor, because of two possible reasons:
1. The field will cross just as many wires in both direction, cancelling out forces (The electromagnetic monopole concept does possibly not work)
2. There is no field gradient along the magnets circumference.


I'll start printing this part out tomorrow. Too late at night now.


Vidar

Low-Q

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Re: Electromagnetic monopole - sort of?
« Reply #1 on: September 28, 2017, 12:19:17 AM »
Maybe an iron core can guide the field away from the entrance/exit part of the coil.

Low-Q

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Re: Electromagnetic monopole - sort of?
« Reply #2 on: September 28, 2017, 01:01:06 PM »
I have learned that the magnetic field from a conducting hollow wire, is on the outside. THere is nothing inside. I do not have a hollow cylinder wire, but something that acts like one. Some of the fields closest to each coil will be on the inside because there is a space between the coils.

Low-Q

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Re: Electromagnetic monopole - sort of?
« Reply #3 on: September 28, 2017, 01:26:03 PM »
Maybe this is how it should be?

Low-Q

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Re: Electromagnetic monopole - sort of?
« Reply #4 on: September 28, 2017, 05:46:39 PM »
Production. Lets hope the experiment is useful :)

Low-Q

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Re: Electromagnetic monopole - sort of?
« Reply #5 on: October 09, 2017, 03:15:05 PM »
A much easier way to make a circular magnetic field, is to wind a toroid without iron core. I checked it out in FEMM using axisymmetric problem type. There is no field outside the toroid. Only inside the hollow part of the windings. The magnetic field goes one way in a circle. I will make one with a plastic core which have a small slot where I can enter the copper wire for easier winding.
Then test it out on the surface of a large doughnut magnet I have, and see what happens. If this work, I will make more coils, and see if it is possible to make a brushless motor that runs on pure DC.


Vidar

Animatesx

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Re: Electromagnetic monopole - sort of?
« Reply #6 on: November 08, 2017, 10:39:10 AM »
It is a serious comment and understanding of information dissemination.