Steady-state analysis of a variable speed traction system using DFI-motor

Variable Speed Traction System (VSTS) equipped with large asynchronous machines are emerging now in electric vehicles applications. This work deals with a conventional configuration of the VSTS which consists on a Doubly-Fed Induction Motor (DFI-Motor) supplied by two power-converters one for the stator windings and another for the rotor ones. It investigates the fundamental steady-state theory of the DFI-Motor and analyzes its behavior using MATLAB. Formulas for currents, active and reactive powers in the stator and rotor terminals as well as electromagnetic torque are deducted as a function of the rotor phasor voltage. The rotor injected voltage is controlled by varying the two parameters of its complex form which are: the magnitude and the internal angle. The simulation results show that proposed control strategy is correct and feasible.