But it is still power in equals power out, so more torque is required to push that 300 Amps. The device is just more capable of doing it, and should/could/would get there at presumably a lower rpm.
But yeah, that is for generators and motors, not alternators.
One supposes that slight additional gains could be wrested from making a more precise surface quality and gap match between the rotor core 'faces', and the stator (magnet core) 'faces'.
They are probably pretty close already though. Something like
0.015" with a 5 thou plus or minus tolerance, allowing the mass production mills to spin 'em off in bigger lots between inspections, and requiring less matching at assembly time.------------------------------ No objection to power in =power out but to the idea that the device will, by going to permanent magnets, can have a higher current capacity.
1) Note that the current rating of an alternator or motor IS NOT determined by the field strength. It is a thermal limitation. For a given speed and winding, the voltage available IS determined by field strength. Certainly, IF you could triple the field strength then you could triple the voltage and power (not the current) or get the rated voltage and power at a lower speed. If you want to triple the current capability - a rewind is needed. My complaint is with "The more magnetic flux = more amps" which is nonsense. 2)Since the best Neodymium magnets have a flux density of about 1.4T and electrical steel can go higher than that (about 1.6T) there is little to be gained - On top of this, the electrical steel in machines is kept below the knee of the saturation curve (say 1.1- 1.2 T) in order to limit core losses (as well as magnetizing current which is not an issue with permanent magnets). You won't get the much higher fields and if you had them, the losses would be higher than those involved with the conventional field winding.Conclusion: If you want a permanent magnet generator or motor- start from scratch with a proper design which takes advantage of the permanent magnet's characteristics .
Small permanent magnet alternators have been around a long time -remember the old bicycle "generators", the faster you go, the brighter the light. Newer magnets do allow more output per unit weight and volume and better efficiencies.
There is no inherent difference between a motor and a generator except for the direction of the energy flow. (electronics such as switching in brushless DC motors excluded as this is not actually part of the energy conversion between electrical and mechanical ).
Don Kelly cross out to reply