Dynamic Modeling of Unbalanced Magnetic Pull in Eccentric Wound Rotor Induction Machine

In this paper, a dynamic model is provided to obtain the waveform of the unbalanced magnetic force in the wound rotor induction machines with static eccentricity. The provided dynamic model is based on the voltage state-space equations of the coupled circuits in the eccentric induction machine. In the model the slotting effect and saturation is neglected and the slot ampere turn is distributed on the slot opening. To avoid computation of the air gap flux density and evade of magnetic pressure integration in each time-step of Runge-Kutta computations and consequently reducing the computation time of dynamic simulations, a static function of the stator and rotor windings’ currents are proposed for computation of the unbalanced magnetic force. The parameter of the proposed function is obtained by analyzing the air gap field density by using winding function theory. Finally, the waveform of the unbalanced magnetic force of the eccentric induction machine is obtained and verified by time-stepping finite elemnt analysis.