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Discussion in 'Electrical Engineering' started by [email protected], Apr 3, 2008.

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  1. Guest

    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).
     
  2. Beachcomber

    Beachcomber Guest

    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.
     
  3. Guest

    31:50 GMT, 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.
     
  4. Guest

    |
    |
    |>On 3 Apr 2008 18:31:50 GMT, 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.
     
  5. Roy

    Roy Guest

    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]
     
  6. Guest

    | 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 :)
     
  7. Roy

    Roy Guest

    From:
    | 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]
     
  8. Don Kelly

    Don Kelly Guest

    ----------------------------
    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
    remove the X to answer

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

    | 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.
     
  10. Roy

    Roy Guest

    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]
     
  11. Don Kelly

    Don Kelly Guest

    ----------------------------
    ------
    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.
    ------------
    \
    ----------
    Yes- for the same reason that the normal laminations are insulated from each
    other. This is done to reduce eddy current losses.
    ---------
    -------------
    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 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.
    --------
    ------------
    That would be the level but a lot of the transformer design has been
    developed and optimised in industry.
    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.
     
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