Losses Characterization in Voltage-Fed PWM Inverter Induction Motor Drives Under Rotor Broken Bars Fault

In this paper, a new analytical methodology is proposed to estimate core losses in line-start and inverter-fed induction motors under rotor broken bars. This methodology can be utilized for different supply and load conditions. Core losses are precisely calculated taking into account the effects of nonsinusoidal distribution of the magnetic flux density due to bars breakage. Furthermore, increase of the stator current side-band components magnitude is considered to estimate Ohmic losses accurately. In order to calculate the above-mentioned losses, distribution of the magnetic flux density and stator currents of the induction motor is simulated using modified winding function method. In this modification, influence of nonlinear characteristics of the core materials is taken into account. Moreover, impacts of the spatial distribution of the stator windings, stator and rotor slots are considered. Two well known CV/F and direct torque control techniques are applied to the modeled motor and the aforementioned losses are calculated in the line-start, and inverter-fed modes. The simulation results are verified by the experimental results.