The field-oriented control of the doubly-fed induction machine: some considerations about steady-state and transients

In this paper some general aspects of primary importance about the steady-state and transients of the doubly-fed induction machine (DFIM) will be shown, as the limited dependence of stator flux on the impressed rotor currents, the strong dependence of inherent machine stability on the direct component of impressed rotor currents, the possibility to define a “reactive torque”, in analogy with the “active torque”-the electromagnetic torque, and by which a deeper machine knowledge and easier control can be reached. A graphical method is explained for obtaining the complete steady-state machine vector diagram. Active and reactive powers working area is discussed. Simulations are carried out in order to verify the machine behaviour