Half-Controlled Converters Connecting Open-End Winding Doubly-Fed Induction Generator to a DC-Microgrid

This paper presents a dual converter system in order to connect a three-phase doubly-fed induction generator (DFIG) to a dc-microgrid. The presented topology is based on two three-phase half-controlled converters connected in series with the generator stator windings, in an open-end winding configuration (OEW). The converters operating principles, pulse-width modulation (PWM) with a synchronization technique, power control, and a zero-sequence current minimization strategies are discussed. Steady-state simulations and experiments were performed for the DFIG generating 500 W and operating at constant torque. Finally, it was verified that the proposed system is able to maintain balanced voltages and currents over the DFIG stator windings, with no significant torque or speed oscillations.