Dual Converter for Connection of a Doubly-Fed Induction Generator to a DC-Microgrid

This paper presents a dual converter-based system in order to connect a three-phase doubly-fed induction generator (DFIG) to a dc-microgrid. The dual converter consists in connecting a three-leg rectifier at each side of the stator windings, in an open-end winding (OEW) configuration, adding up to two rectifiers and therefore six converter legs. Usually, these legs are composed of Insulated Gate Bipolar Transistors (IGBTs). In order to reduce the number of controlled semiconductor switches and the cost of the system, one of the rectifiers has its IGBT switches replaced by diodes. Pulsewidth modulation (PWM), power control and a zero-sequence current minimization strategies are discussed. Simulation and experimental results were also obtained, showing steady state results for a 0.56 kW DFIG operating at unity power factor.