This lecture utilizes the analytical approach to show that set of three phase coils supplied with three phase currents will produce a rotating magnetic field in free space.
It is furthermore, demonstrated that the speed of rotation of the rotating magnetic field is related to the frequency of the supplied currents. For two pole stator, the speed of rotation and frequency of electrical signals are equal.
The direction of rotation of the rotating magnetic filed can be reversed by swapping electrical connections to any of two coils on the stator.