Analytical Analysis of Cage Rotor Induction Motors in Healthy, Defective, and Broken Bars Conditions

This paper presents a 2-D static analytical method in the frequency domain for the calculation of magnetic field distribution, eddy-currents, circuit model parameters, and steady-state performances in multiphase/multipole cage rotor induction motors with integer and fractional stator winding. The complex model allows to study the healthy, defective, and broken bars conditions in these electrical machines. The proposed static analytical model considers stator and rotor slotting with tooth-tips. The method is based on the resolution of Poisson's, Laplace's, and Helmholtz's equations in stator slots, air-gap, and rotor bars regions, respectively. The electromagnetic torque is obtained from both the electrical equivalent circuit and Maxwell stress tensor that is given by the magnetic field calculation. The analytical results are validated by those issued from time harmonic finite-element method.