Who among us in childhood did not try or at least did not think about how to build a perpetual motion machine on permanent magnets? It would seem that if the magnets are repelled from each other by the poles of the same name, then it is probably possible to find such a configuration of magnets when the repulsion acts continuously, and can, for example, rotate the rotor of a "perpetual motion" engine.
However, as soon as we tried to implement this idea practically, it immediately turned out that in reality the rotor still finds a position in which it stops. It was as if the rotor had been spinning only to eventually find that point and stop there. That is, a stable equilibrium of the rotor inevitably occurred.
The tendency of thermodynamic systems to equilibrium
And this is not at all surprising, because scientists have long known that thermodynamic systems tend to equilibrium, and in the end, they are in stable equilibrium (static or dynamic).
From mechanics, we know that a body is at rest or moves uniformly and rectilinearly if no external forces act on it, or if the action of these external forces on the body is compensated, that is, the total force is zero (there is no resulting external influence).
As you can see, the principle of thermodynamic systems striving for equilibrium also applies to purely mechanical systems. So, if the system initially remains in stable equilibrium (and a structure with permanent neodymium magnets is no exception), then when such a structure is exposed to an external factor that puts the system out of equilibrium, a reaction from this system will inevitably arise.
This means that the system will begin to strengthen processes that tend to reduce the influence of an external factor that brought the system out of balance (the Le Chatelier — Brown principle).
Model of a magnetic generator by an Indian blogger from the Creative Think channel:
In order to create a desire for equilibrium, it is necessary to create non-equilibrium conditions
A well—known example from electrodynamics is Lenz's rule. If the Lenz rule did not work, then electric motors could not function.
In an electric motor, an electric current creates a magnetic field that causes the rotor to continuously seek equilibrium, and so that the rotor does not stop, the magnetic field acts all the time in such a way that it forces the rotor (even under mechanical load) to constantly catch up with the point at which equilibrium will occur.
But at the same time, the electric field acting in the conductors performs work, that is, the energy of the source is consumed, because in the engine there is at least friction of the shaft against the bearings, which, even if the rotor is not loaded and the engine is idle, requires work, that is, energy consumption.
If there were no friction (even against air) and the shaft was not loaded, the rotor would spin for a very long time, for example, in a complete vacuum in the absence of an attractive force to the Ground. But then no work would be done by this rotor, and it would no longer be an engine, but a piece of metal rotating without resistance.
Let us now return to permanent magnets. For a system with permanent magnets, it is not difficult to predict the direction of the balancing reaction process.
So, back in the 90s, the Japanese experimenter Kohei Minato investigated the possibility of creating continuous rotation using permanent magnets on the rotor and stator of his motor. Eventually, it was also forced to create a changing magnetic field that would force the rotor to seek equilibrium.
Minato demonstrated how by bringing a permanent magnet closer or farther away, a permanent magnet rotor can be forced to rotate. But in the end, he simply reached in experiments with a motor with permanent magnets on the rotor.
There was no perpetual motion machine. To change the external magnetic field, which would repeal the rotor with magnets, requires energy from the outside. That is, to create conditions in which the rotor with magnets will seek equilibrium, it is necessary to perform work in parallel.