Dynamic induction machine model accounting for stator and rotor slotting

A method for dynamic modelling of induction machine with a doubly slotted air gap is proposed and implemented for the case of a cage induction motor. The described method is easily extensible to wound rotor machines. A numerical description of the air gap permeance is provided that takes into account a slotted stator and rotor structure as well as their mutual, time and space dependant positions as a function of rotor rotation. The multiple coupled circuit model approach is used with the modified winding function in order to calculate the inductance of all motor windings. The developed model is general in nature and could be used for the analysis of different dynamic regimes of induction machine, particularly different combinations of stator and rotor slot numbers. Model validation is provided by stator current spectrum analysis of a standard four pole induction motor with S=36 and R=32 slots. The experimental results presented clearly support these findings.