Another friend of mine from grad school did his thesis on something like this. http://dspace.mit.edu/handle/1721.1/18013 http://dspace.mit.edu/handle/1721.1/18

Another friend of mine from grad school did his thesis on something like this. http://dspace.mit.edu/handle/1721.1/18013 http://dspace.mit.edu/handle/1721.1/18013 "We propose a novel variation of a doubly-fed induction generator which aims to improve power density and simplify construction. Our design is a doubly-fed, dual-rotor, axial-flux, permanent-magnet machine." The magnets for that thing were truly scary. Every once in a while I gave him a hand with the assembly and it took three or more of us to safely install each magnet in the rotor.