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Topic Title: DC Alternator concept Questions.
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Created On: 11 June 2013 05:21 AM
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 11 June 2013 05:21 AM
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Nicadeamas

Posts: 7
Joined: 11 June 2013

.
Howdy, In my run around on the internet this has been the best place I've found to ask these questions, so hopfully you fellows will be able to help me out or point me in the right direction.

I've got crazy idea's in my head and I would like some advice before I spend more money trying to build them.
Ultimately the purpose of my intended creation is a DC alternator. Put DC current In, add physical rotation, get DC current out. Except like an alternator, I want the current I get out to be greater then the current I put in.
So let me explain from the start,
I know that if you run a copper wire 'down' through a magnetic field with north on the 'left' then the result is the electrons will move predominately away from you. (If north is on the left.)
www
.i.imgur.com/daE84MD.jpg



So, my first question, and probably the most important. Say you take 5 wires and connect them on either end, then pass them through the magnetic field. Assumable the result would be the same as one wire times 5.
But what if you took a copper block the size of 5 wires and passed it through the field? Would you get the same result?
www
.i.imgur.com/BlX5o1M.jpg


Furthermore, what if you used the same concept to try this;
www
.i.imgur.com/Two20P3.jpg



If you could arrange a magnetic field to have lines of force pointed toward the center of a cylinder, then would you be able to put a copper pipe in that cylinder, rotate it, and get a voltage on the other side comparable to the amount of rotation you apply?
I can understand how this may not work due to the electrons not being limited to a linear path (forward/backward) but if you were using wires set up in a pipe shape, would you be able to achieve a DC voltage via the magnetic field?

Then if we used electric magnets(coils) to create the magnetic field, we would be able to control the output by controlling the input voltage for the coil. (alternator.)
But again, what if we used a copper block instead of a series of wires?
www
.i.imgur.com/w9lYS7M.jpg



And this brings me to the concept I'm shooting for. If in fact you could use a strip of copper rather then wires, then what if you had a copper disk, where the magnetic fields are made via copper rings on either side of the disk, to make the magnetic lines of force cut through the mid range of the disk.
The goal is to cause the electrons from the center of the disk, to want to move to the outer edge of the disk, when the disk is rotated.
And the copper rings are intended to create a magnetic field in the shape of a torus that the disk is cutting.
Note: It is very important that the current created is a constant, unchanging purely DC current, that can be manipulated by the speed of rotation, and electric current induced on the coils on either side of the disk.
www.
i.imgur.com/yeCXR0c.jpg
 11 June 2013 09:05 AM
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ectophile

Posts: 541
Joined: 17 September 2001

All your links have been deleted because the IET forums get plagued by spammers posting links to stuff they want to sell.

It looks like you've just invented a form of homopolar generator - Wikipedia.

-------------------------
S P Barker BSc PhD MIET
 11 June 2013 04:55 PM
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kengreen

Posts: 400
Joined: 15 April 2013

I think your major problem is thqt youi are extremely muddled in your thinking - your query, in truth, does not make sense. What exactly do you mean by a DC Alternator ? An electric current can be steady in value and unidirectional (a DC), varying in value but unidirectional (DC Signal),, varying in value but constantly changing its direction of flow (an AC Signal) or steady in value but continually changing its direction of flow (a Continuous Wave from an Alternator -but this term is usually used in reference to a spinning machine.).

Did I get that right ? :-)

If I am to believe that which you have written you are trying to develop a unidirectional current that is not unidirectional?

The answer t your positive question is that a copper block will behave exactly as a single conductor - which is what it is.
 11 June 2013 05:55 PM
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Nicadeamas

Posts: 7
Joined: 11 June 2013

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@ Ectophile
.
WOW!
This is very encouraging. For the longest time I've been thinking to myself, either someone else has got to have tried this idea, or it just doesn't work.
If you are interested, here is the whole question above in picture format. (One big image rather then a lot of little ones.)
www
.i.imgur.com/MTioAHJ.jpg
(www is cut off to trick the site, sorry.)

@ Kengreen
Hmm...
I think you are as confusing to me, as I am to you. But I like the way you talk, this could be an interesting relationship.
My goal is to generate a DC current at about 2-3 volts, and 10 - 50 amps. I suppose the value can vary but so long as it remains DC it will work. Though, I would prefer a constant value that only changes when the speed of rotation, or induced magnetic field change.

I am very confused about car alternators. They seem to consist (Basically) of two coils, one on he inside, the other made around it. The inside one is energized to create a magnetic field, but it is rotating, so the magnetic field is rotating. Which causes the outer set of coils to cut through the lines of force and generate a current.

But what I am confused about, is that it seems to pass a coil of wire through a magnetic field. Half the coil would pass through the magnetic field, and generate a current traveling away from you (If North is on the left.)
Which means on the other side of the coil, since it is a circle, the current will be traveling toward you. But then as the coil continues it's path through the magnetic field and the other half of the coil goes through the magnetic field, then it generates a current traveling in the opposite direction of the current you already have in the wire. (This would make sense to me if it were the cause of CEMF)
But because the coil going through the magnetic field is spun clockwise or counter clockwise, it is able to generate it's own magnetic field which will ultimately result in a predominate flow of current with a background flow heading in the opposite direction (CEMF)
So to me the whole principle behind the design of motors, alternators, and generators seems flawed because half of every coil in the device is pointed in the wrong direction.

But now I'm getting sidetracked off topic.
I have two goals.
- 1. Create a controllable DC current of 2-3 volts, at 10 - 50 amps.
- 2. Have no CEMF created. (That one I understand is supposed to be impossible.)

Thank you for your replies, they have been very encouraging and I've enjoyed reading and thinking about them.
 12 June 2013 12:34 PM
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kengreen

Posts: 400
Joined: 15 April 2013

In the language of the horsey people - you have got off on the wrong foot and so are off balance..

For a start - you are allowed to be confused over car "alternators" because they are NOT ... but then again they are ... if you get my meaning :-)

Any spinning machine generates an alternating current (an AC) and here is where you encounter the need to use the language with accuracy. The "dynamo" , which used to feature in cars et al, is in fact an AC machine but it has incorporated in its design a mechanical switch which reverses the connection every time the current reverses and so the output is a (very noisy) DC ? As such is is customary to call it a dynamo.

Your main confusion I think lies in failure to grasp that a spinning coil has one limb moving (say) right to left while its opposite member is moving left to right and so throughout the coil the current moves in the same direction ?

The field windings are arranged so that they produce a linear magnetic field across a gap in which the coil rotates.

Are you familiar with Fleming's left-hand and right-hand Rules which encapsulate the relation between direction of Magnetic field, the direction of Current-flow and the relative direction of motion with respect to the magnetic field and the conductor ?

Ken Green
 13 June 2013 07:15 AM
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Nicadeamas

Posts: 7
Joined: 11 June 2013

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Oh I see I see.
Your right, you are saying that the inner coil of a alternator and other motors are shaped parallel to the shaft like this, (www)
groschopp.com/wp-content/uploads/armature-parts_small.jpg

Rather then perpendicular to the shaft like this,
slotcarcollectibles5.homestead.com/files/MT_armature.JPG

I understand that a spinning coil in a generator will produce an AC or produce a wavering (noisy) DC with commutators.
I understand the manor in which voltage (difference in potential) is created through magnetic fields as explained in videos such as this;
youtube.com/watch?v=IpaEGhjpZgc

I understand much of the right/left hand rules. It was very confusing for me because they seemed to contradict and I did not know that some people teach that current flow is from negative to positive while others teach it is from positive to negative.
I do wonder, if the electrons are traveling away from you in a wire, why does their magnetic field rotate counterclockwise? (left hand rule.) What dictates the direction of the wires magnetic field?

Do you think the concept of the Homopolar generator can compete with the traditional generator designs?
Do you think if a disk were spinning in a evenly spread magnetic field that the disk would have less drag?

Thank you for your replies, this has been very educational and thought provoking for me.
 13 June 2013 08:51 AM
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ectophile

Posts: 541
Joined: 17 September 2001

Originally posted by: Nicadeamas
I understand much of the right/left hand rules. It was very confusing for me because they seemed to contradict and I did not know that some people teach that current flow is from negative to positive while others teach it is from positive to negative.


The problem is that electrons have a negative charge.

Batteries were invented before electrons were discovered. At some point, somebody decided to label the terminals of a battery "positive" and "negative", and decided that current flowed from the positive to the negative.

Unfortunately, when electrons were discovered, it turned out they had a negative charge. So the electrons are really flowing from the negative to the positive.

Ever since, we've had the problem that the "conventional" direction of an electric current is the opposite to the actual flow of electrons.

-------------------------
S P Barker BSc PhD MIET
 14 June 2013 06:07 AM
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Nicadeamas

Posts: 7
Joined: 11 June 2013

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This explains much. Thank you. I think my questions are answered for now. I'm going to go gather scrap materials, solder some stuff up, make things spin, and come up with more questions.
Bwahahhaaa!
Thanks.
 12 September 2013 05:49 AM
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Nicadeamas

Posts: 7
Joined: 11 June 2013

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New thought.
In respect of North. meaning, looking down on north. It appears everything (Earth, sun, moon, etc) rotates counterclockwise. Apparently even electrons are supposed to rotate counterclockwise.

So, wouldn't that mean with a homopolar generator specifically, it would function better if it were spinning counterclockwise rather then clockwise?
 19 September 2013 10:07 PM
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kengreen

Posts: 400
Joined: 15 April 2013

Nicadeamas,

You are getting confused because even the best scientists abuse the English language. Before you start to talk about anything be it a conductor bent into circular form, a disc or any object which is spinning the terms clockwise and anticlockwise are meaningless unless supported by a reference frame? Consider any object which is spinning; view it from "above" and note its direction of rotation. Now view it from "below" and you will see it as rotating in the opposite direction .
Ken Green
 22 October 2013 05:16 AM
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Nicadeamas

Posts: 7
Joined: 11 June 2013

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Thank you.
Your information has been most helpful as my idea's projects move slowly along.
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