Modelling and analysis of series-connected wound rotor induction motor

Wound rotor three phase induction motor with series connected stator and rotor winding is an object of analysis in this paper. This type of connection enables specific operating regime when induction motor works as a synchronous motor at double synchronous speed. Electromagnetic torque analysis shows that other synchronous torque could also be expected at 2/3 of synchronous speed. Multiple coupled circuit model is derived and numerical simulation is provided. Results of numerical simulation confirm existence of electromagnetic torque at both speeds.