Seeking Answers to Magnetic Field Transfer Questions

[lengould]

At the risk of being in the wrong thread, here goes:

I've been haunting the (limited, for me) avail. literature and physics forums looking for the answer to a question relevant to some posts here re: eg "I've performed thousands of experiments involving homopolar, unipolar, and acyclic generator and motor topologies. They all are real and work (eg. they produce EMF or MMF predictably.)" I know enough magnetics (engineer level) to calc with field strengths, current levels using given formulae in known problems, but can't find a formula for this problem. Physics is not beyond an introductory honours course at UofT in '68.

The reason I'm looking is related to a current US patent application of mine at http://appft1.uspto.gov/netacgi/nph...=DN/20040212259

or goto http://appft1.uspto.gov/netahtml/PTO/srchnum.html and type in application number 20040212259

It covers three new configurations of synchronous electric motors, the second of which exploits the above configuration to excite the rotor pole pieces. eg see {images}, {drawings}, {Fig 5}. (OR I've posted the image at my website at http://www.ecologen.com/images/Wheelmotor_fig5.jpg). The exciter magnet is the stationary drum at the centre 14 with ring extensions 16 up each side of the stator to connect magnetically with the rotating pole pieces 6.

My question is: Presuming eddy currents are defeated, how much power will be lost in transfering the magnetic field from the fixed exciter to the rotating pole pieces? Seems a fair bit of work has been done investigating/proving that rotating a cylindrical magnet doesn't rotate the field, but that's not really relevant here. I think that the energy expended at the gap between the fixed exciter and the pole pieces to move the pole pieces 6 relative to the exciter won't be anywhere near as large as that spent at the gap between the pole pieces and the stator. How do I calculate that (fairly) exactly?

Thanks

 

[Andrew Mason]

My question is: Presuming eddy currents are defeated, how much power will be lost in transfering the magnetic field from the fixed exciter to the rotating pole pieces? Seems a fair bit of work has been done investigating/proving that rotating a cylindrical magnet doesn't rotate the field, but that's not really relevant here. I think that the energy expended at the gap between the fixed exciter and the pole pieces to move the pole pieces 6 relative to the exciter won't be anywhere near as large as that spent at the gap between the pole pieces and the stator. How do I calculate that (fairly) exactly?

I infer from the lack of responses to your question, that no one is able to understand the question. I couldn't access the USPTO drawings for some reason but I was able to look at the patent and the drawing on your website. It would be helpful if you could post the descriptions as well (ie. of what the numbers point to).

Essentially it appears to be is a dc induction motor with no commutator/brushes. Does the central fixed part (ie fixed to the axle) - the exciter - contain induction coil magnets or permanent magnets? I assume they would be induction coils but I don't see them drawn there. Does your question relate to the power transferred to the fixed excitor windings (by induction) compared to the available power in the stator windings?

If so, it would be just an application of Faraday's law. You would have to figure out the flux that passes through the area enclosed by the excitor windings. I don't think there is any way to calculate this in principle because it depends on the design of the stator and excitor magnets. The key would be to make the excitor windings cover a large area but little depth, and have the stator windings cover a small area with significant depth and as close to the excitor windings as possible so the excitor windings intersect as much of the stator flux as possible. You would then run it and see how the induced current in the excitor compares to the current in the rotating windings.

AM

 

[ravenprp]

for the interesting question and for sharing your patent application. I am not an expert in magnetics, but from my understanding, the transfer of magnetic field from the exciter to the rotating pole pieces would depend on several factors such as the strength of the exciter magnet, the distance between the exciter and the pole pieces, and the speed of rotation of the pole pieces. In order to calculate the exact energy loss, you would need to consider all of these variables and possibly use some complex mathematical models or simulations.

One approach could be to use the concept of magnetic flux linkage, which is the product of magnetic flux and the number of turns in a coil. You could calculate the flux linkage at the gap between the exciter and the pole pieces, and then compare it to the flux linkage at the gap between the pole pieces and the stator. This would give you an idea of the relative amount of energy that is transferred at each gap.

Another approach could be to use Faraday's law of induction, which states that the induced electromotive force (EMF) in a closed loop is equal to the rate of change of magnetic flux through the loop. By knowing the rate of change of magnetic flux at each gap, you could calculate the EMF and then use it to determine the amount of energy lost in the transfer.

I would suggest consulting with a specialist in magnetics or conducting some experiments to validate your calculations. Additionally, there may be some existing research or literature on similar configurations that could provide insights into the energy transfer in this type of system.

I wish you the best of luck with your patent application and I hope you are able to find the answers you are seeking.