Frequency domain numerical analysis of rotor cage induction motor

This paper proposes a method of finite elements analysis (FEA) of the rotor cage induction motor. In case of an induction motor supplied with constant voltage, the current during starting process is not constant. For that reason, FEA in frequency domain at constant current is not appropriate for direct start simulation. A motion analysis is required, the rotor speed being computed according to magnetic field values. The main disadvantages are that such analysis requires considerable time and hardware/software resources. In order to eliminate these shortcomings, this paper proposes a frequency domain analysis, stator winding being fed with constant (nominal) voltage. The torque-slip, current-slip curves and the parameters variation during direct start process can be obtained, without requiring however a numerical analysis with motion. The results obtained by this method are compared to those given by equivalent circuit parameters and by measurements.