Two Orthodox Objections

An expert comments

I recall mentioning to a colleague a long time ago that I was going to look seriously into the question of over-unity or "free energy" permanent magnet motors, especially ones exploiting magnetic repulsion.

This individual would be best described as a (usually) friendly skeptic, an internationally recognised expert in some areas of orthodox electrical technology, although not a leading expert on rotating electrical machines. His response was not encouraging. Although I can't remember the exact words, he said something like:—

"Well, there are plenty of permanent magnet motors out on the market already, aren't there? And I think you'll find that not one of them delivers any free energy!"

And:— "There's also a repulsion motor on the market, which certainly doesn't deliver any free energy!"

Permanent magnet motors

Large permanent magnet synchronous motor "Permasyn." Image from http://www.industry.siemens.com/verticals/global/en/marine/marine-ships/propulsion/Pages/permasyn-drive-motor.aspx

It's quite correct that motors incorporating permanent magnets have been available for many years. One large category of them is sometimes called IPM (Internal Permanent Magnet) motors. Textbooks, such as shown below, have been written on them.

Permanent Magnet Motor Technology, Jacek F. Gieras and Mitchell Wing,
Second Edition, 2002.

However, a quote from this book (p13) suggests a problem:—

The application of PMs [Permanent Magnets] to electrical machines improves their efficiency by eliminating the excitation losses. The air gap magnetic flux density increases, which means greater output power for the same main dimensions.

Not the only application

This quote is early on in the book, in its Introduction. It implies that elimination of excitation losses is the only application for permanent magnets in electrical machines. I found nothing else in this book to suggest otherwise. At a minimum, that indicates a serious lack of imagination. Could it even indicate deliberate suppression? As will be seen in future posts, there are certainly other applications for permanent magnets in electric motors — but apparently not orthodox ones already on the market.

Repulsion motor

I'll comment on the so-called "repulsion motor" next time. Some confusion in the orthodox world has to be cleared up about what is, and what is not a repulsion motor.

Electromagnetic Repulsion

Having dismissed the possibility of over-unity performance for electromagnetic attraction (in the absence of permanent magnets, at least), what about repulsion? Could electromagnetic repulsion forces be made to exhibit over-unity performance?

A deep question

This question is not trivial or easily dismissed. I think we are now getting involved in the deep problem of the incompatible differences between positive and negative electrical potential energy.

Showing two magnets attracting (left), and two magnets repelling (right).

Magnetic repulsion is not just some kind of "converse" or "mirror-image" of magnetic attraction. In the above images, two magnets are initially far apart, and are then brought closer together. In the attracting case (left) a single magnetic circuit is created, as flux lines from the two magnets have joined together. In the repelling case (right) the magnetic circuits of the two magnets always remain separate. Flux lines are compressed and distorted, and do not join into a single circuit.

Electromagnets

If the attracting or repelling magnets are in fact electromagnets, this different behaviour implies that there will also be differences in how energy is taken from and returned to the electrical source.

When two electromagnets are energized to attract, and deliver mechanical energy by moving closer together, the volume of the airgap between them decreases, and so does the magnetic energy stored in it. So at the end of the stroke there is much less magnetic energy available to be returned to the electrical source. (Nevertheless, in conventional devices like switched reluctance motors, this relatively small amount of residual energy is returned, using regeneration circuits. I'll have more to say about that topic in future).

On the other hand, when two close-together electromagnets are energized to repel, and deliver mechanical energy by moving further apart, the volume of the airgap between them increases, and so does the magnetic energy stored in it. So at the end of the stroke there is a maximum of magnetic energy available to be returned to the electrical source. At the start of the stroke the reluctances of the two opposing magnetic circuits will be relatively high, and more energy may be drawn from the source as the electromagnets move apart, but all that electrical energy (less minor losses) is ultimately available from the two magnetic circuits to be returned to the source, just as it would be for two completely separate electromagnets acting only as inductors.

What do the textbooks say?

About two decades ago I had the opportunity to consult various textbooks in a specialized library for heavy-current electrical technology. None of the following textbooks contained anything useful about energy conservation for repelling electromagnets in general:—

Siemens Electrical Engineering Handbook, Siemens Aktiengesellschaft, Berlin 1969

Standard Handbook for Electrical Engineers 11th Edition, Donald G. Fink and H. Wayne Beaty, McGraw-Hill 1978

AEG Manual, 8th Edition, Allgemeine Elektricitäts-Gesellschaft, 1966

The Magnetic Circuit, V. Karapetoff, McGraw-Hill, 1911

Higher Electrical Engineering, J. Shepherd, A. H. Morton and L. F. Spence, 2nd Edition, Longman Scientific & Technical

Electric Circuits and Machines, 2nd Edition, A Mychael, McGraw-Hill, Sydney

Worked Examples in Electrotechnology, 7th Edition, W. T. Pratt, Hutchinson Technical Education, 1968.

One useful reference

The single reference I have ever found that deals with this issue in sufficient detail to be of any use at all is Newtonian Electrodynamics, Peter Graneau and Neal Graneau, World Scientific 1996. On p18 the authors have this to say (my emphasis in last paragraph):—

     In potential theories there have always existed difficulties in agreeing on a universal sign convention. Kellog ... pointed out that the most popular rule was to assign negative potential energy to elements of like sign which attracted each other, and positive potential energy to elements of like sign which repelled each other. Gravitating particles were an example of the former class, and electric charges were an example of the latter class. If matter elements have signs attached to them, they normally represent scalar quantities. Current elements are not of this nature. They have definite directions and therefore they are vectors. Depending on their directions, two current elements sometimes attract and sometimes repel each other. Hence it would seem the potential energy of current elements, and circuits made up of these elements, may sometimes be positive and at other times negative, leaving us to ponder what could be meant by negative energy? We cannot conceive of less than no energy. Consequently, positive and negative potential energy must be two kinds of energy, like positive and negative charge are two kinds of electricity. One kind of potential energy would be associated with attraction and the other with repulsion. Unlike charge, however, the two kinds of energy cannot be neutralized by putting them together.

Figure 1.10. Electrodynamic potential energy of straight and parallel currents

     To see this more clearly, let us now examine two very long straight and parallel wires m and n, as sketched in figure 1.10. In case (a) of that figure they carry currents in the same direction. From experience we know that they will attract each other. By the rules of potential energy they are therefore associated with negative potential energy. Assume an externally applied force Fx tends to increase the separation x and brings about the displacement ∂x by moving n to n'. This external force has to do work and expend an amount of energy equal to Fx∂x. At first it may be thought that this energy is being added to the stored potential energy. This cannot be so, however, because the magnitude of the electrodynamic potential given by [Franz Neumann's expression for the mutual potential of two closed circuits composed of Ampèrean current elements] decreases as a result of the lengthening of the distances between current elements. Not only does the mechanical source sustaining the external source supply energy to the system of conductors, but the potential energy store also gives up energy. What absorbs these two streams of energy? As the currents are assumed to remain constant, no additional Joule heat will be dissipated. Later we will show that, according to Neumann's theory, all of this energy flows to the two electrical sources that maintain the currents. Some of the Joule heat normally furnished by these sources will, during the displacement of one conductor from n to n', be supplied by the potential energy store and the mechanical energy source.

     In the case of figure 1.10(b), where the currents flow in opposite directions and the conductors repel each other, the displacement x from n to n' again requires the supply of energy by the mechanical source exerting the external force, but now the magnitude of the stored energy increases because of the shortening of element distances. This opens the possibility of all the energy provided by the mechanical source being stored as potential energy, and the electrical sources maintaining the currents are either not involved in the transaction or they exchange energy with each other. 

     To appreciate that in a system of conductors positive potential energy does not cancel negative potential energy, we consider three parallel and equidistant wires A, B, and C, in accordance with the model of figure 1.10. If A and B carry current in the same direction, the associated stored energy will be negative, say -P. Let the current in the wire C flow in the opposite direction to the current in B. Then the energy stored between B and C will be positive, that is +P. The forces inside the two sets of conductors do not eliminate each other, and therefore +P-P ≠ 0! The fact that the interaction between A and C adds further positive energy to the system does not change the argument. We have to conclude that positive and negative potential energy are two different kinds of energy which might as well have been named "red" and "green" energy.

My UAER motor.
("UAER" = "Unenergized Attraction — Energized Repulsion")

Energy not necessarily conserved?

I think the above quote supports my contention that energy is not necessarily conserved overall in the specific case shown again here, using the principle of a magnet first being attracted-in to an unenergized electromagnet core ("negative" energy), and subsequently repelled-out by electromagnet to permanent magnet repulsion ("positive" energy).

The above quote is far from a definitive answer to my contention, but it does indicate how deep the underlying issues are.

Experiments needed

Of course real-world experiments, rather than textbook comments, are required to finally decide this. Shortly I'll look at a professionally designed and built prototype motor that exploits exactly this principle over the most significant part of its operating cycle, and which a little research will show was fairly obviously designed as a free energy motor.

But next, it is necessary to deal with a couple of orthodox objections.