In view of the serious current harmonics in a doubly-fed induction generator(DFIG)-DC connection sys-tem and the large loss of a dual-voltage source inverter(VSI) connection system,a novel dual-converter connection system which connects a three-phase DFIG to DC microgrid is designed. First,the topology,pulse-width modulation (PWM) measurement and DFIG model of the dual-converter connection system are described in detail. Different from the traditional connection systems,the proposed connection system adopts an open-end winding structure and uses a three-bridge arm rectifier on each side of the stator winding. Considering that these arms are usually composed of insulated gate bipolar transistors(IGBTs),a diode is used instead of the IGBT in the rectifier to decrease the number of control switches and reduce the cost. Second,the control strategies for a stator-side converter(SSC) and a rotor-side convert-er(RSC) under the new topology are given. Third,a comparison with the DFIG-DC connection system and the dual-VSI connection system is performed through simulations,and results show the advantages of the proposed method in terms of current harmonic distortion,torque ripple and semiconductor loss. Finally,experimental verification was carried out on a 0.56 kW DFIG,and results also verified the advantages of this method in terms of loss,harmonics and torque ripple.
维普
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