FEM analysis of inverter-induction motor rotor conduction losses

A direct method to simulate the steady-state stator and rotor currents in an inverter-induction machine of known geometry and winding design is developed, and the FEM (finite element method) analysis of the skin effect problem is used to determine the variation of rotor resistance with rotor current frequency. The rotor conduction loss can be calculated from these two sets of information. The total losses incurred for a particular mode of inverter operation are determined both experimentally and using the analytical procedure developed here. The total calculated loss is only 3.5% greater than the measured amount, which confirms the validity of the theory developed and its computer implementation. Furthermore, experimental and simulation results of the standstill condition with sinusoidal input were also found to be in close agreement. Finally, the proposed procedure yields information on the instantaneous current distribution throughout the machine, which permits the accurate determination of the flux pattern and optimization of the lamination design