magnetic fields

[[email protected]]

I'm on a quest to find a good book that covers information about magnetic
fields as it applies to power and/or radio engineering. For power, this
would be things like generators, motors, and transformers. For radio, it
would be a lot about antennas. Right now my preference is for the power
side of this.

Doing searches through Amazon and B&N I find many books about things like
motors and transformers. But pretty much everything is about how to do
things like install, maintain, and repair them, or select them for various
applications. There are some that cover the theory, but they did not look
to be the best choices. I am interested more in things like the design of
devices like generators, motors, and transformers, with respect to how the
magnetic fields are used and shaped, particularly for specialized devices
handling non-ordinary needs. A typical motor, for example, just turns a
rotor, and has a classic axial construction. I'm interested in unusual
things like non-rotary motion devices (electric pistons, for example) as
well as unusual rotor motion devices, such as ring motors that have no axis
at all. The focus I am looking for in an ideal book is on the design or
the exporation of designs for a wide variety of devices, with an emphasis
on how the magnetic fields are shaped and operate, whether coupling to
electric windings, or interfacing with mechanical motion of any kind.

Pure electromagnetic or magnetodynamic theory is not the interest. Nor is
the manufacturing, selection, installation, maintenance, or repair of such
devices (though something that focused on the very unusual devices might
provide some insight into their design).

 

[Beachcomber]

A lot of the math for AC machines was perfected and published at the
beginning of the twentieth century. Check out the published works of
Charles Steinmetz and N. Tesla. Their work allowed optimal machines
to be built without testing every conceivable prototype.

http://en.wikipedia.org/wiki/Charles_Proteus_Steinmetz

Tesla was more secretive and jealous of his patents, so you may not
find as much technical detail in his published works.

 

[[email protected]]

31:50 GMT, [email protected] wrote:
|
|>I'm on a quest to find a good book that covers information about magnetic
|>fields as it applies to power and/or radio engineering. For power, this
|>would be things like generators, motors, and transformers. For radio, it
|>would be a lot about antennas. Right now my preference is for the power
|>side of this.
|>
|>Doing searches through Amazon and B&N I find many books about things like
|>motors and transformers. But pretty much everything is about how to do
|>things like install, maintain, and repair them, or select them for various
|>applications. There are some that cover the theory, but they did not look
|>to be the best choices. I am interested more in things like the design of
|>devices like generators, motors, and transformers, with respect to how the
|>magnetic fields are used and shaped, particularly for specialized devices
|>handling non-ordinary needs. A typical motor, for example, just turns a
|>rotor, and has a classic axial construction. I'm interested in unusual
|>things like non-rotary motion devices (electric pistons, for example) as
|>well as unusual rotor motion devices, such as ring motors that have no axis
|>at all. The focus I am looking for in an ideal book is on the design or
|>the exporation of designs for a wide variety of devices, with an emphasis
|>on how the magnetic fields are shaped and operate, whether coupling to
|>electric windings, or interfacing with mechanical motion of any kind.
|>
|>Pure electromagnetic or magnetodynamic theory is not the interest. Nor is
|>the manufacturing, selection, installation, maintenance, or repair of such
|>devices (though something that focused on the very unusual devices might
|>provide some insight into their design).
|
| Voice coils spring to mind. That is a linear motor.
| You can salvage some parts from a hard drive to play with one. The
| older and bigger, the better. If you could track down an IBM 3330
| voice coil assembly you would have something worth doing some work
| with. (coil the size of an oat meal can and magnets like paving
| bricks, 3" stroke). On the other end of the scale is a regular
| speaker.
| If you couple this with a lot of coils and a controller you have a
| linear accellerator that you can shoot like a gun

I'll hunt around in my basement to see if I have some old 3330's I'm no
longer using Actually, the 3350's looked like more awesome magnets.

Right now I'm focusing on looking for the information on how magnetic fields
are engineered for various things including this. Yes, a voice coil is a
very good example of a specialized magnetomotive device.

One interest I would have is substituting a magnetically driven device like
this (which a voice coil could very well work) for the escapement of a clock
as a means to electrically control an otherwise mechanically operated clock.
One approach would be a mechanical escapement that is driven magnetically to
overpower the gear forces. Another idea is to make a gear that instead of
teeth, has alternating magnetic bars, and just drive it entirely from the
field of two coils.

A couple years ago I mentioned the idea of making toothless gears by having
alternating magnetic bars in each "wheel" that engage each other magnetically.
The same wheel can be the rotor of a permanent magnet syncronous motor, too,
by driving it from a sufficient number of electromagnetic windings. One of
the things I want to explore is the diversity of winding shapes that can be
used for doing such things, either for motor drives, or as a generator to
either produce power from some primary mover, or to sense motion (which could
also be done optically in a powered system).

I have no one particular goal at this time, other than to learn more about
the way magnetic fields can be constructed. Maybe this will inspire some
creative idea.

 

[[email protected]]

|
|
|>On 3 Apr 2008 18:31:50 GMT, [email protected] wrote:
|>
|>>I'm on a quest to find a good book that covers information about magnetic
|>>fields as it applies to power and/or radio engineering. For power, this
|>>would be things like generators, motors, and transformers. For radio, it
|>>would be a lot about antennas. Right now my preference is for the power
|>>side of this.
|
| A lot of the math for AC machines was perfected and published at the
| beginning of the twentieth century. Check out the published works of
| Charles Steinmetz and N. Tesla. Their work allowed optimal machines
| to be built without testing every conceivable prototype.
|
| http://en.wikipedia.org/wiki/Charles_Proteus_Steinmetz
|
| Tesla was more secretive and jealous of his patents, so you may not
| find as much technical detail in his published works.

The math will help. I'm also looking for geometric ideas. That is, how
can a magnetic field be shaped in different ways for unusual devices,
either in the form of motive interfaces or electrical interfaces.

Consider, for example, a pair of steel wires spiraling around each other.
A current in one of them (steel isn't the best conductor, but is usable)
should induce a magnetic field in the other. Now consider what if at
the looped around end, they switch such that on the 2nd pass, the current
is now going through the "other" wire. Both should now have current AND
a magnetic field, I would think (since it is effectively one wire). Now
to figure out how to get the current into this wire without breaking the
magnetic field. Something else coupling to it would seem right. Maybe
a separate copper wire (everything being insulated or separated) running
along side? Maybe a current transformer? Not that there is anything
useful that could ever be made from this; it's just exploratory ideas.

 

[Roy]

Phil, you looked in Barnes & Noble?
Also: From what I've read so far Oxford Press has some good books on
Theory, Exotic Materials & Quantum Physic...I'm sure magnetism is in
there someplace.

Then again it's essential to be wise & understand that anything ism &
any term ending in ism is void & disipated.A magnetic spectrum quantity,
may produce a radio spectrum waveform, which would eventually excite any
receptive field within range.

* [ all to be denounced as bullshit by some abherant wisenheimer, until
the next use of an " ism " } ]

Question: What waveform [part of the spectrum] are you attempting to
transmit or receive ? in radionics it's more a matter of blocking a
signal and retransmitting it to an available medium.,

[*] The first stage magnetics power application would be in micro
scale., then the transformer theory will have to be applied with loss &
regenerated with somekind of power transistor circuit for the final
stage to emit the signal...I guess looking at a gauss meters function in
reverse could help to understand & actually see this happening at a
magnetic waveform level.

Note: for hardwired systems you may have to consult an Awesome Verizon
Guy }

Roy Q.T. ~ US/NCU ~ E.E. Technician
[have tools, will travel]

 

[[email protected]]

| Phil, you looked in Barnes & Noble?

That was the first place I looked.


| Also: From what I've read so far Oxford Press has some good books on
| Theory, Exotic Materials & Quantum Physic...I'm sure magnetism is in
| there someplace.

That seems to be a bit more to the theory side than I want. I'm looking
more to a design side, but a design of the unusual (as opposed to the
rigorous design of the small minor details of the common).


| Then again it's essential to be wise & understand that anything ism &
| any term ending in ism is void & disipated.A magnetic spectrum quantity,
| may produce a radio spectrum waveform, which would eventually excite any
| receptive field within range.
|
| * [ all to be denounced as bullshit by some abherant wisenheimer, until
| the next use of an " ism " } ]
|
| Question: What waveform [part of the spectrum] are you attempting to
| transmit or receive ? in radionics it's more a matter of blocking a
| signal and retransmitting it to an available medium.,

Not any particular waveform or frequency in particular. My interest in
antennas would be to be able to project radio energy into a particular
pattern or shape.


| [*] The first stage magnetics power application would be in micro
| scale., then the transformer theory will have to be applied with loss &
| regenerated with somekind of power transistor circuit for the final
| stage to emit the signal...I guess looking at a gauss meters function in
| reverse could help to understand & actually see this happening at a
| magnetic waveform level.
|
| Note: for hardwired systems you may have to consult an Awesome Verizon
| Guy }

If he can hear me now

 

[Roy]

From: [email protected]
| Phil, you looked in Barnes & Noble?
That was the first place I looked.
| Also: From what I've read so far Oxford Press has some good books on |
Theory, Exotic Materials & Quantum Physic...I'm sure magnetism is in |
there someplace.
That seems to be a bit more to the theory side than I want. I'm
looking more to a design side, but a design of the unusual (as opposed
to the rigorous design of the small minor details of the common).

Then again it's essential to be wise & understand that anything ism & |
any term ending in ism is void & disipated.A magnetic spectrum quantity,
| may produce a radio spectrum waveform, which would eventually excite
any | receptive field within range.

* [ all to be denounced as bullshit by some abherant wisenheimer, until
| the next use of an " ism " } ]

Question: What waveform [part of the spectrum] are you attempting to |
transmit or receive ? in radionics it's more a matter of blocking a |
signal and retransmitting it to an available medium.,

Not any particular waveform or frequency in particular. My interest in
antennas would be to be able to project radio energy into a particular
pattern or shape.

snip/ some important stuff snipped

Note: for hardwired systems you may have to consult an Awesome Verizon |
Guy }

If he can hear me now
| Phil Howard (ka9wgn.ham.org)
_____________________________
Well that seems to be a bit too broad., but all I know is it's rather
basic., with antenna design - whatever you fancy., later we can strive
to integrate it systematically if & when neccesary.

In Theory there is a strong base for any design in formulation.,
consider a must know for instrumentation & harmonic coupling at the
least.

Good Luck - I'll get back to you if anything else occurs to me...

Roy Q.T. ~ US/NCU ~ E.E. Technician
[have tools, will travel]

 

[Don Kelly]

----------------------------

31:50 GMT, [email protected] wrote:
|
|>I'm on a quest to find a good book that covers information about
magnetic
|>fields as it applies to power and/or radio engineering. For power, this
|>would be things like generators, motors, and transformers. For radio,
it
|>would be a lot about antennas. Right now my preference is for the power
|>side of this.
|>
|>Doing searches through Amazon and B&N I find many books about things
like
|>motors and transformers. But pretty much everything is about how to do
|>things like install, maintain, and repair them, or select them for
various
|>applications. There are some that cover the theory, but they did not
look
|>to be the best choices. I am interested more in things like the design
of
|>devices like generators, motors, and transformers, with respect to how
the
|>magnetic fields are used and shaped, particularly for specialized
devices
|>handling non-ordinary needs. A typical motor, for example, just turns a
|>rotor, and has a classic axial construction. I'm interested in unusual
|>things like non-rotary motion devices (electric pistons, for example) as
|>well as unusual rotor motion devices, such as ring motors that have no
axis
|>at all. The focus I am looking for in an ideal book is on the design or
|>the exporation of designs for a wide variety of devices, with an
emphasis
|>on how the magnetic fields are shaped and operate, whether coupling to
|>electric windings, or interfacing with mechanical motion of any kind.
|>
|>Pure electromagnetic or magnetodynamic theory is not the interest. Nor
is
|>the manufacturing, selection, installation, maintenance, or repair of
such
|>devices (though something that focused on the very unusual devices might
|>provide some insight into their design).
|
| Voice coils spring to mind. That is a linear motor.
| You can salvage some parts from a hard drive to play with one. The
| older and bigger, the better. If you could track down an IBM 3330
| voice coil assembly you would have something worth doing some work
| with. (coil the size of an oat meal can and magnets like paving
| bricks, 3" stroke). On the other end of the scale is a regular
| speaker.
| If you couple this with a lot of coils and a controller you have a
| linear accellerator that you can shoot like a gun

I'll hunt around in my basement to see if I have some old 3330's I'm no
longer using Actually, the 3350's looked like more awesome magnets.

Right now I'm focusing on looking for the information on how magnetic
fields
are engineered for various things including this. Yes, a voice coil is a
very good example of a specialized magnetomotive device.

One interest I would have is substituting a magnetically driven device
like
this (which a voice coil could very well work) for the escapement of a
clock
as a means to electrically control an otherwise mechanically operated
clock.
One approach would be a mechanical escapement that is driven magnetically
to
overpower the gear forces. Another idea is to make a gear that instead of
teeth, has alternating magnetic bars, and just drive it entirely from the
field of two coils.

A couple years ago I mentioned the idea of making toothless gears by
having
alternating magnetic bars in each "wheel" that engage each other
magnetically.
The same wheel can be the rotor of a permanent magnet syncronous motor,
too,
by driving it from a sufficient number of electromagnetic windings. One
of
the things I want to explore is the diversity of winding shapes that can
be
used for doing such things, either for motor drives, or as a generator to
either produce power from some primary mover, or to sense motion (which
could
also be done optically in a powered system).

I have no one particular goal at this time, other than to learn more about
the way magnetic fields can be constructed. Maybe this will inspire some
creative idea.

There are many texts that cover the basics of what you want. The older ones
do put emphasis on magnetic "paths" and optimisation of them (basically-
keep air gaps to a minimum and work the iron just below the knee of the B-H
curve) and all do deal with the whole business of force production -whether
in solenoids, motors or whatever, in terms of energy balances. These are
generally at the junior to graduate EE university level. Unfortunately,
they do require some basic calculus at the minimum. Some lower level texts
do cover much of this for simple situations such as loudspeakers. The basic
concepts apply to the things that you want to explore.
For example, winding shapes/locations may or may not be important depending
on what the winding is intended to do but often simply become a case of what
is practical for the purpose.

Try looking for texts on "electromagnetic energy conversion" rather than
"motors".
I also may be able to send you some notes in pdf or word form- with your
correct address.



--

Don Kelly [email protected]
remove the X to answer

P.S. your escapement can be provided by a stepper motor or simply pulsing a
solenoid.

 

[[email protected]]

| There are many texts that cover the basics of what you want. The older ones
| do put emphasis on magnetic "paths" and optimisation of them (basically-
| keep air gaps to a minimum and work the iron just below the knee of the B-H
| curve) and all do deal with the whole business of force production -whether
| in solenoids, motors or whatever, in terms of energy balances. These are
| generally at the junior to graduate EE university level. Unfortunately,
| they do require some basic calculus at the minimum. Some lower level texts
| do cover much of this for simple situations such as loudspeakers. The basic
| concepts apply to the things that you want to explore.
| For example, winding shapes/locations may or may not be important depending
| on what the winding is intended to do but often simply become a case of what
| is practical for the purpose.
|
| Try looking for texts on "electromagnetic energy conversion" rather than
| "motors".
| I also may be able to send you some notes in pdf or word form- with your
| correct address.

One thing I am curious about is shaping the magnetic field. Normally if I
have one simple winding, I'm going to have a certain rather common field shape
looping inside the coil and back outside of it all around it. And the field
would have a highest density somewhere near the coil (exactly where is one
thing to know) and gradually decrease in density as the distance grows. But
if I insert additional coils, there will be a combined effect of the fields.
In much the same way as multiple elements of a radio antenna can shape the
emission pattern, this is what I want to learn about for magnetic fields.
Suppose I want a field that has a particular shape in a certain cross section?
What if I want a field that is relatively flat in density up to a point and
then falls off rapidly? This goes to things like minimizing the effect and
coupling of the field in certain directions, while maximizing it in others,
with or without shielding. Or maybe "active shielding" which could be in
the form of added small coils to cancel out some of the field in certain
places where it is undesired. Or maybe "controlled shielding" which could
be those added coils being energized or not depending on immediate needs as
determined and controlled by a special driving circuit (or computer).

OK, I guess that wasn't _One_ thing

More thoughts:

And ... the magnetic field of the Earth itself would be something to learn
more about. I do know a nearby electromagnetic field strong enough can
overtake the Earth's field at that point and control a compass needle.

I've heard that some transformers are made with steel wires instead of steel
plates as the core. Do they have to be "insulated" from each other?

What are the advantages and disadvantages of winding coils separately on
different sides of a square core vs. both windings over each other or even
mixed together around the center bar of the core?

I asked last year about a motor idea where the stator was driven in one
direction and instead of having permanent magnets on the rotor, it was
driven with a rotating electromagnetic field, too (have as many phases as
might be useful, 3, 6, 12, etc), and in the opposing direction. The idea
was to get a syncronous motor with the rotor going at twice the speed as
one with simple permanent magnets would. Coupling the power into it might
be a trick to make it practical.

I would expect this stuff to be junior/senior EE, at least for power track
majors. All the EE I ever took in school was a couple courses, one in audio
electronics, and one in digital design. I didn't have the in-depth curiosity
for other stuff as I do now.

My email can be derived from my signature, or by removing appropriate the
"-news-nospam" part from the posting header email. PDF is easiest for me
to view.

 

[Roy]

I was always a bit put off by calculus - though I did find it's
assertive points interesting, they are too elusive to make anything out
of anything with calculed formulation alone - a little looking into
quantum physics gave me a whole new perspective, because you can relate
the practice of theory better with a plausible reference in matter.
For Solid State as it's callled, the important thing is to find what
serves your muse or design parameters to a "T".

Roy Q.T. ~ US/NCU ~ E.E. Technician
[have tools, will travel]

 

[Don Kelly]

----------------------------

| There are many texts that cover the basics of what you want. The older
ones
| do put emphasis on magnetic "paths" and optimisation of them
(basically-
| keep air gaps to a minimum and work the iron just below the knee of the
B-H
| curve) and all do deal with the whole business of force
production -whether
| in solenoids, motors or whatever, in terms of energy balances. These are
| generally at the junior to graduate EE university level. Unfortunately,
| they do require some basic calculus at the minimum. Some lower level
texts
| do cover much of this for simple situations such as loudspeakers. The
basic
| concepts apply to the things that you want to explore.
| For example, winding shapes/locations may or may not be important
depending
| on what the winding is intended to do but often simply become a case of
what
| is practical for the purpose.
|
| Try looking for texts on "electromagnetic energy conversion" rather than
| "motors".
| I also may be able to send you some notes in pdf or word form- with your
| correct address.

One thing I am curious about is shaping the magnetic field. Normally if I
have one simple winding, I'm going to have a certain rather common field
shape
looping inside the coil and back outside of it all around it. And the
field
would have a highest density somewhere near the coil (exactly where is one
thing to know) and gradually decrease in density as the distance grows.
But
if I insert additional coils, there will be a combined effect of the
fields.
In much the same way as multiple elements of a radio antenna can shape the
emission pattern, this is what I want to learn about for magnetic fields.
Suppose I want a field that has a particular shape in a certain cross
section?
What if I want a field that is relatively flat in density up to a point
and
then falls off rapidly? This goes to things like minimizing the effect
and
coupling of the field in certain directions, while maximizing it in
others,
with or without shielding. Or maybe "active shielding" which could be in
the form of added small coils to cancel out some of the field in certain
places where it is undesired. Or maybe "controlled shielding" which could
be those added coils being energized or not depending on immediate needs
as
determined and controlled by a special driving circuit (or computer).

------
It appears that you are considering "air core" situations and the approach
to the questions that you pose would require some form of field mapping
rather than an analytical approach. Very messy. The basic Maxwell's
equations would apply but in such cases, numerical analysis would be needed.
At one time, there were plotting tanks for 3D analysis and "teledeltos"
paper (conducting) for 2D cases. These are resistive analogs and
equipotentials could be plotted- following this, field lines could be
plotted on the basis of "curvilinear squares" (i kid you not). THe same
techniques apply to stream flow, electrostatic fields,etc. but now are done
through computer programs.
------------
\

OK, I guess that wasn't _One_ thing

More thoughts:

And ... the magnetic field of the Earth itself would be something to learn
more about. I do know a nearby electromagnetic field strong enough can
overtake the Earth's field at that point and control a compass needle.

I've heard that some transformers are made with steel wires instead of
steel
plates as the core. Do they have to be "insulated" from each other?

----------
Yes- for the same reason that the normal laminations are insulated from each
other. This is done to reduce eddy current losses.
---------

What are the advantages and disadvantages of winding coils separately on
different sides of a square core vs. both windings over each other or even
mixed together around the center bar of the core?

-------------
There is always some leakage inductance so that ideally it is best to have
the coils as close to each other as possible to minimize the flux that leaks
or doesn't couple both windings. It is pretty awkward to mix the coils
together (particularly for higher voltages) so it is best to have the
windings one on top of the other, and often the windings are split so that
each leg of the transformer has half of each winding. Spacing between
windings and between winding and core will depend on insulation needs and
cooling requirements. EHV windings will be actually be wound on "pancakes"
because of insulation needs as well as capacitance distribution.

I asked last year about a motor idea where the stator was driven in one
direction and instead of having permanent magnets on the rotor, it was
driven with a rotating electromagnetic field, too (have as many phases as
might be useful, 3, 6, 12, etc), and in the opposing direction. The idea
was to get a syncronous motor with the rotor going at twice the speed as
one with simple permanent magnets would. Coupling the power into it might
be a trick to make it practical.

------
I remember that discussion. It seems that what was needed was that the
field of the rotor, as seen by the stator had to be at synchronous speed.
--------

I would expect this stuff to be junior/senior EE, at least for power track
majors. All the EE I ever took in school was a couple courses, one in
audio
electronics, and one in digital design. I didn't have the in-depth
curiosity
for other stuff as I do now.

------------
That would be the level but a lot of the transformer design has been
developed and optimised in industry.

My email can be derived from my signature, or by removing appropriate the
"-news-nospam" part from the posting header email. PDF is easiest for me
to view.

Ok- I will dig up and modify some old notes and get them off to you. Some
deal with magnetic forces and others deal with induction and synchronous
motors.