Design and analysis of practical induction motors

A method to estimate the flux-linkages and parameters of induction motors w ith skewed rotor bars is presented. The proposed method is based directly o n a multi-slice time stepping finite element model, hence the effects of sa turation, eddy-current, skewed rotor bars and high-order harmonic fields, c an all be included readily in the solution. Special formulas for calculatin g rotor currents, rotor flux-linkages and air-gap flux in quadrature-phase winding system are deduced. The computed currents and flux-linkages from th e finite element model are used directly to compute the parameters of the l umped circuit model with the help of the least squares method. The advantag es of the proposed method are its simple physical concept, high accuracy an d versatility. The method is suitable to study virtually all modes of opera ting conditions, including dynamic operations, of induction motors.