Losses Calculation in Line-Start and Inverter-Fed Induction Motors Under Broken Bar Fault

In this paper, a new analytical method is proposed for Ohmic and core losses calculation in induction motors under broken bar fault. In this method, new coefficients are introduced to consider non-sinusoidal distribution effects of flux density due to bar breakage. Then, core losses of induction motors in this condition are estimated. In order to calculate Ohmic losses in faulty induction motors, impacts of the bar breakage on the harmonic components of the stator currents are taken into account. Furthermore, influence of the control strategies on the precise determination of the aforementioned losses is investigated in detail. Hence, the constant voltage per frequency and direct torque control methods as global control strategies are applied to the analytical modeling of the induction motor under broken bars. In this modeling approach, the effects of the nonlinear characteristics of the core materials, stator, and rotor slots are taken into account. The simulation results are verified by the 2-D time stepping finite-element method and experimental results.