Research on the reconfigurable inverter applied in Microgrid

The paper proposes a new reconfigurable inverter with secondary fault-tolerant(FT) capability, which can improve the reliability of microgrid. When a primary fault occurs in a power switch of the inverter, the capacitor bridge on the DC side is used to replace the faulty phase; and the inverter is reconfigured as the three-phase four-switch (TPFS) topology to realize the first fault-tolerance. Then if a fault occurs again in another power switch, the inverter is also reconfigured again to realize the second fault-tolerance. To assure the normal FT operation, a FT pulse control algorithm is used to reset the SPWM pulse signals. Additionally, because of the deviation of the DC neutral point voltage, a corresponding control strategy is proposed which can effectively suppress the capacitor voltage deviation. The simulation results verify the correctness of the reconfigurable inverter topology applied in microgrid and the effectiveness of the control strategy.