Lorentz and Bodine's E-Torq 2

[HCBFlash]

Bodine's E-Torq motor documentation speaks of "Faraday motors", but this motor being a Lorentz based design. My brief study of H.A. Lorentz's work essentially leads me to believe that Bodine is in effect claiming their design defies our understanding of electicity and magnetism, and essentially produces force from "the aether". Any insights?

 

[electricpete]

"The brushless, dc e-TORQ motor, however, has an iron-free stator comprising a flat copper coil sandwiched between permanent-magnet rotors"

Doesn't sound like ether to me. It has two sources of field which interact. Do you know if the input is pure dc or if it requires a special power supply like bldc motors?

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[sreid]

HCBflash,

I agree with you, the E-Torq motors operate using the same principle that all motors use. Air core motors eliminate iron slot cogging effects. Air core brush type motors have been used for years (disk and cup motors).

 

[electricpete]

I don't get what you guys are saying. What is the claim that is incorrect or violates the laws of physics or has something to do with ether?

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[HCBFlash]

Well, "air core" is pretty close to something that Lorentz or his translators might have thought of as "aether" I suppose. Still, simply copper windings without any ferromagnetic material for magnetic field concentration sounds like something that would have very poor efficiency, and actually power to weight and power to size ratios too.

electricpete, it uses Bodines electronic drive.

I don't particularly have any interest in Lorentz, unless he describes something that is very useful in a very clear understandable way. ....not quite what I found in a brief search and cursory review. So it seemed like a red herring to me.

sried, "air-core" is something I've heard of, but never actually thought twice about.

I'm studying and trying to learn as much as I possibly can about electric motors, as a hobby of sorts, and this forum is a fantastic place. There are a couple folks here that I really find impressive. A few people positively bristle at "student posting", and I hope this doesn't somehow appear to be one. I think everyone on this website is a student of sorts, or I can't imagine why they'd be on here.

Any other insights would be deeply appreciated.

 

[electricpete]

There are lots of ways to generate electromagnetic force, and iron is not a prerequisite. I think the useage of Lorentz here is as in Lorentz force law F = q V x B = L I x B. If the current carrying conductor is directly in the flux, it will experience a force. I didn't notice any claims about efficiency or size/weight ratio. So I still don't get the objection.

A short tangent that you may or may not have heard before, if the conductors are located in slots in an iron core, then the electromagnetic force does act primarily on the iron, not the conductor (in spite of the fact that many textbooks teach it differently). At the following link I have provided some information on that subject including a 10-page short version a 60-page long version, and a video demo showing both force on conductor and force on iron:

http://home.comcast.net/~electricpete1/torque_web/

As far as student posting, it is simply a matter of forum policy. The site is for practicing engineers.

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[electricpete]

sreid - At the risk of being repetitive to my last post, I wanted to respond directly to your comment. I would say that the air core motor operates with a different principle than typical motors (for example industrial induction motors) from the standpoint mentioned above. In the air core motor, the electromagnetic torque-producing forces act primarily on the conductor. In a typical induction motor with conductors in slots, the electromagnetic torque-producing the forces act primarily on the iron.

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[HCBFlash]

Pete,
Thanks loads. You should post most of the stuff (short and long versions etc) as whitepapers. I think the acrobat ads aren't really what the whitepaper section is for anyhow.

 

[Clyde38]

Thanks!

 

[sreid]

Electricpete,

You are, of course, exactly right. I find, however, that the "Force in the iron" explanation simply confuses the understanding of how a motor works. "The copper wire pushes on the iron" vision results in exactly the same forces and torques. And we design motors based on lenghts and number of turns of wire.

 

[HCBFlash]

I don't want to beat this to death, but looking further at the Bodine lit, I do question a bit of it.

I quote (by cut-and-paste)

"motors based on Faraday’s principles are the most
common today, they may not be the
most efficient due to the interaction
of the magnetic and mechanical
forces inherent in the design.
Both, Lorentz and Faraday’s motors
use the electromagnetic properties
to create mechanical work, but
the way the forces are applied in a
Faraday motor means the motor is
always trying to “reshape” itself.
By contrast, the e-TORQ™ motor’s
design allows the maximum application
of electromagnetic forces
with almost no mechanical energy losses."

I don't see the efficiency improvements in the motor itself, but rather in Bodine's suggested application to "eliminate gearboxes". Am I missing something here?

 

[sreid]

Here's a link to an air core printed circuit motor (disk motor).

http://www.phys.unsw.edu.au/hsc/hsc/electric_motors5.html

 

[electricpete]

sreid- I agree that we can predict motor behavior very well by "pretending" the force acts on the conductors. There are a whole lot of textbooks that have elaborate mathematical derivations based on this exact thought process. The one small hitch is that you have to substitute B=Bgap as if the conductor is directly in the airgap flux (which it isn't). Many textbooks just write the force on conductor equations alongside pictures of conductors in slots and never explain why they use B=Bgap for the force equation. So, it creates imo a large potential for misunderstanding... and it's a little bit of a hotbutton topic for me because of some past arguments on this topic. So before I get carried away, perhaps I'd better just that whitepaper as suggested and start another thread.

The link posted above indicates the windings rotate (connected through brush) and the magnets stationary... With that setup you can power from dc (also called a homopolar motor). The bodine link mentioned stationary windings and rotating magnets.. .which I believe can run on ac. (? is that an ac motor?). But I think fairly similar principles apply.


HCB - Let's dissect your quote.
"motors based on Faraday’s principles are the most common today"
Faraday's principle is v = L di/dt - he must be talkiong about induction motors. Yes, those are the most common.

" they may not be the most efficient due to the interaction
of the magnetic and mechanical forces inherent in the design."
I'm not sure exactly what that means. But there is some inefficiency in providing the rotor excitation accross the airgap...lowers the power factor.

"Both, Lorentz and Faraday’s motors use the electromagnetic properties to create mechanical work"
Pretty vague, but I can't disagree.

" but the way the forces are applied in a Faraday motor means the motor is always trying to 'reshape' itself."
Well, they could be talking about the fact that the rotating magnetic field creates a rotating deformation of the stator. It can cause some vibration and perhaps very small efficiency reduction.

"By contrast, the e-TORQ™ motor’s design allows the maximum application of electromagnetic forces with almost no mechanical energy losses."
Yes, the rotating deformation is gone. Whether or not it's efficient, I don't know.

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[electricpete]

Your question about gearboxes - it's tough to make a cheap low speed inducation motor. As you know it operates at speed 2*LF/p. For lower speeds we need lots of poles which increases cost. The same does not apply to some of these other designs like the Bodine and the homopolar.

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[sreid]

electricpete,

Someone asked about air core motors and I found a good link to a printed circuit motor, the first air core motor I ever saw. The E-Torque motor has stationary, "flat" windings sandwitched between two rotating plates with N-S-N-S..... magnets on them. I can't find any good pictures of "Axial Field Brushless Motors."

 

[Clyde38]

Pete,
What happened to your video?

This link no longer works:

http://home.comcast.net/~electricpete1/torque_web/

 

[electricpete]

Sorry about that. It seems that my ISP comcast is having some problems since they "upgraded" our web page capability.

Here is another link:

http://electricpete1.tripod.com/torque_web/

(This link is from Tripod.... in exchange for webspace they put their own advertisemens on the page. Also they launch a variety of pop-ups and cookies which are annnoying but I think harmless).

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[electricpete]

I am sure they are harmless since I have surfed there many times and never seen a problem. I know they put some kind of cookie called "tribalfusion" on my computer that my viruschecker always removes.

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[Clyde38]

Thanks again, I had shared this with a friend and it came up misssing.