A novel fault-tolerant control scheme for Shunt Active Power Filter with high reliability

Due to the demand for increasing the reliability and efficiency of Shunt Active Power Filter (SAPF), this paper proposes a novel fault-tolerant control scheme for SAPF. When phase failure occurs, the inverter topology can be reconfigured from three-phase six-switch structure into three-phase four-switch which is achieved by connecting the endpoint of fault phase to the midpoint of DC-bus. On this basis, the working principle and influence of DC voltage fluctuation and unbalance are analyzed. Then an equalization control strategy is put forward to equalize the two spilt capacitor voltages. Finally, one kind of voltage space vector for fault-tolerant SAPF is deduced which is helpful to generate the driving signals and modulate the remaining semiconductors. The proposed control scheme is applied to a 50kVA prototype and the experimental results have validated its efficiency and feasibility.