interpoles is widely use to improve commutation place between main poles fitted to yoke functions: to neutralize armature mmf in commutating zone to produce some flux in commutating zone
In all machine stator and rotor magnetic field rotates (stationary with respect to each other) at synchronous speed with respect to stationary observer.
due to fractional pitch EMF can be approximately made into sine wave losses due to harmonics reduced saving in conductor material mechanical strength of coil is increased.
EXAMIANS