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

This article presents a novel system to connect a three-phase doubly fed induction generator (DFIG) to a dc-microgrid. The proposed topology is based on two three-phase half-controlled converters connected in series with the generator stator windings, in an open-end winding configuration. The converters operating principles, pulsewidth modulation, power and air-gap flux controls, and zero-sequence current minimization strategies are discussed. The proposed system is compared with conventional systems in terms of current harmonic distortions, torque ripple, and semiconductor losses. Simulations and experiments were also performed, showing steady-state and transient results for the DFIG generating 500 W. Finally, it was verified that the proposed system can operate with lower power losses and maintain low-distorted voltages and currents over the DFIG stator windings.