Yes I suspect what i was trying was impossible. Its a nice idea to play with though! How could one arrange magnets, coil and shielding so that one leg of the coils (say the inward/hubward leg) is cut by more magnetic flux than he other leg (say the outward/rimward leg)? If this can be done in anyway, a DC generator (brushless) could be made!
Anther idea which arises now is maybe flaps of light steel that flip as the magnets pass, alternately shielding and exposing parts of the coil... well probably impossible as you say, but hey it cant hurt to think about it.
En groetjies aan jy ook!