Finite element calculation of double-cage rotor equivalent circuit parameters

This paper describes the use of a saturable single slot finite element model to determine the resistances and reactances of a double-cage rotor, allowing for the MMF balancing effect of the stator currents. The method is verified by comparing the impedances calculated for an unsaturated rotor with rectangular bars with their analytically determined counterparts. The model requires the user to specify both rotor frequency and current per slot. The effect of magnetic saturation is examined, and it is demonstrated that care must be taken in the choice of current at low frequencies, to avoid conditions of excessive saturation, leading to unrealistic values for inductances