I’ve been having Rare Earth Supermagnets made just for me to build my generators for several years.
Pretty darn expensive, and if they get hot, they get ruined. Weird chemicals (elements) make one cautious using them or breathing their dust if they break, etc. (By the way, watch those fingers!)
Now a group from The U.S. has supposedly a got a way to make even stronger magnets from iron nitride. I guess the key is managing the crystal structure.
Promised to be cheaper, more environmentally friendly, easily available to be made anywhere from common materials, and more heat resistant.
Currently, neodymium magnets are rendered inert around the temperature of boiling water.
That’s pretty bad. A major issue with SuperMagnets in motors and generators, which tend to get very hot.
GM is attracted to these new non-rare earth magnets for its EV motors - The Verge
I KNEW THERE HAD TO BE A CATCH (woops - capslok) with this material. It’s been researched for over a decade, but they still can’t manufacture magnets yet. AND the material can be more magnetic than Neodymium magnets, BUT the Iron Nitride magnets can be easily DEMAGNETIZED due to a low coercivity. Oh well. I was hoping…
Tesla’s Rare Earth Free Motor // Niron Iron Nitride or Ferrite Magnets? - YouTube
Why use permanent magnets at all? Reluctance generators, or Induction generators, or alternators using excitation coils dont use any permanent magnets at all.
I guess this is so obvious that experts in motor design are aware of the design conpromises involved.
An immediate guess of why is how to excite the wires? On a magnet motor only the stator is wired and the rotor does not need wiring. It may be difficult to provide wired to a moving part, involving perhaps slip rings. Just a wild guess though.
You loose some efficiency and power density, but you get a less expensive motor/generator because you don’t have to use magnets. And you don’t have to depend on China for rear earth materials for the magnets.
Many years ago i remember Tesla was boasting about using a induction motor on the model S because that meant they did not have to rely on China for neodymium magnets. But now they use permanent magnet synchronous reluctance motors just like every other EV out there because of the higher power density and efficiency.
But still there is a reason why induction motors is totally dominant in industrial factory’s used for pumps, agitators, and so on.