What role does permanent magnet strength play in BLDC/PMSM performance?

Question

It seems to me like stronger permanent magnets are preferred by motor designers, but my current understanding of what role they play in performance is fuzzy at best. I would assume that stronger magnets would imply stronger torque, but I'm not sure what else that implies.

So let me ask the question this way: take motors one has weaker Ferrite magnets, and the other has N52 Neodymium magnets, but are otherwise identical. How would they compare along these attributes:

• Torque Curve
• Max Power Output
• Electromechanical efficiency
• Thermal performance

And to extend on that question, do those same effects extend to differences in electromagnetic strength? What, for example, would happen if you took an iron core motor and just removed the cores, thereby reducing the magnetic strength?

Answer 1

The weak magnet otherwise identical motor will spin faster on the same supply volts .So maybe you should reduce the supply DC volts to the weak magnet machine to keep rpm the same .Now if you want some torque and load the weak magnet machine you will need more armature current for the same torque so copper losses are greater and thermal perfomance is inferior .So the stronger the magnets the better.