A general approach of space and time harmonics interactions in induction motors

The interactions of space and time harmonics must be considered precisely during the design process of induction machines to achieve good motor performance. They also influence the harmonic content of the stator currents which can be used for sensorless speed detection or to monitor internal defaults of the machine. In this paper, the authors use a general representation of time and space harmonics in induction machines to explain their mechanism of production and their interactions. A simple analytical method is derived to quantify precisely the harmonic content of the instantaneous torque, currents and flux in both stator and rotor windings, in terms of fixed parameters of the machine structure. The method is validated by field calculation and experimental tests