Direct Analysis of Three-Phase Induction Motor Considering Rotor Parameters' Variation and Stator Belt Harmonics Effect

In this article, a novel procedure for the induction motor analysis is presented, avoiding the time-domain finite element problem formulation. The proposed technique closely links the mathematical model of the motor to the finite element simulations, concerning magneto-static and time-harmonic analyses. The target of the method is to include, in a rapid machine computation, also the effect of the slip frequency on the bars' current distribution and the induced currents in the cage due to the stator belt harmonics. The reported analysis example concerns the stand still operation of a double cage induction machine, where the rotor frequency is the grid frequency and the high stator current intensifies the role of the belt harmonics. A further application example concerns a flux weakening working point of a single cage induction motor in a variable speed drive. The aim of this work is to propose procedures to get a fast prediction of the induction motor performance, including also the principal parasitic effects, e.g. the rotor bars' skin effect and the stator belt harmonics, without using any time-domain analysis.