Interbar current analysis of induction motors using 3-D finite-element method considering lamination of rotor core

The losses and efficiency of induction motors are analyzed considering the interbar currents, which flow from the rotor bars into the rotor core. The three-dimensional (3-D) finite-element method with the modeling of the laminated rotor core is applied in order to take the skin effect and the magnetic saturation of the core into account. The calculated losses and efficiency are compared with the measurement. The measured and calculated results agree well. It is clarified that both the rotor core and rotor cage losses increase due to the interbar currents and that the main components of these losses are caused by the stator slot harmonics