ABSTRACT
In AC machines, windings are distributed in such a way that a rotating magnetic field is generated by a polyphase AC source. Apart from the efficiency in electric power transmission, the three-phase system allows for the generation of a rotating field. A perfect sinusoidal traveling magneto motive force (MMF) is obtained only when the coil is distributed sinusoidally and when the three-phase current is also sinusoidal. But in practice, both coil distribution and current have high-order harmonics. The former is called space harmonics; the latter current harmonics. This chapter considers MMF harmonics for a non-sinusoidal coil distribution. The balanced three-phase variables have only two degrees of freedom and can be mapped into a complex plane. The best way to construct a mapping rule from three-phase variables to the complex plane is to visualize the flux vector that would be generated in the cross-section of the motor.
