Rotor-side converter reconfiguration using four-switch three-phase topology in dfig-wt for fault-tolerant purpose

A four-switch three-phase (FSTP) rotor-side converter (RSC) is proposed in this paper for doubly-fed induction generator based wind turbines (DFIG-WT) to increase the system reliability. The proposed converter topology has satisfactory robustness to open-circuit faults, and it is demonstrated to be feasible under the circumstance of wind speed change. According to different current flow directions, the model of FSTP RSC is set up. In addition, the space vector pulse width modulation (SVPWM) technique is simplified in FSTP RSC to get rid of sector identification and complex trigonometric calculations when a converter fault occurs. Besides that, the amplification of DC-bus voltage is reduced by using the proposed modulation technique. The overall performances are analyzed for both the six-switch three-phase (SSTP) and FSTP RSC based DFIG-WTs with wind speed step changes in Matlab/Simulink. The validity of the proposed FSTP RSC is demonstrated and it has the potential to be applied in practice.