[mfrykman]

Not positive, but I think there are scaling issues w AC induction motors. My understanding is that for smaller applications, they don't make sense.

Anyone have more insight on this?

[ChuckMcM]

Power dissipation in the electromagnets is the limiting factor. The more current you push through them the more power you dissipate in the windings. To offset the resistance you can make 'thicker' (current is a surface area effect but mass is a thermal sink) wires but that reduces you Ampere turns which reduces flux. Since room temp superconductors aren't an answer, you top out.