That's a tough question... while I can't claim to have designed anything outright in particular in our motors I can let you know that EVERYTHING plays an important role in the motor's performance.
Yes, a rotor can be somewhat difficult to design and get right considering all of the factors involved such as magnetic strength/path, weight, diameters, stiffness, heat resistance, hardness, etc etc
Just as important is the stator: the design of the laminations themselves...
The sensor assembly has to be carefully laid out and placed as well for proper operation...
I believe that there's always more than one way to skin a cat... but it takes a lot of attention to detail to look at everything and try to make the very best overall package that you can.
We're already seeing more and more companies buying chinese built motors and simply slapping a label on them or anodizing them a little different color ... and unless they start taking on the challenge of trying to design and manufacture their own rotors/laminations then they're pretty much going to be stuck with whatever is on the chinese menu so to speak.
Different design philosophies will no doubt shape the changes that people start to make... so that will be interesting to see where people try to take these designs in the future.
Originally Posted by syndr0me
What's the most difficult component to design/manufacture in a brushless motor? My guess would be the rotor?
If that's the case, I'm curious if we'll see people eventually make/wind their own motors, and design them with the intention of using someone else's rotors, so they can pretty much leave that potentially difficult part out of the equation.