Study of the induction machine under transient duty and steady-state as synchronized motor

The synchronized operation mode of the three-phase induction machine (synchronized induction machine - SIM) can be equated with a three-phase wound-rotor induction machine that operates under unbalanced duty. In this case, the SIM is analyzed by means of first order differential equations that contain nothing but total fluxes and the rotation angle as variable quantities. It is about an equation system that include 8 equations corresponding to the 3 stator phases, 3 rotor phases (two of the rotor phases are series-connected and form the excitation winding) and 2 movement equations. This approach offers valuable information on the instantaneous phenomena that take place inside the machine. On the basis of this information, one can adopt proper strategies concerning the most favorable moment for the connection of the windings to the supply sources in order to avoid faults such as pulling out, for instance. The hodograph of the resultant rotor flux is used as an effective tool for the evaluation SIM behavior under different duties such as transients or steady-state.