Abstract: The fault-tolerant control of active power filter（APF）has component redundancy，which leads to the increase of fault-tolerant control error，the decrease of execution efficiency and fault-tolerant rate. Aiming at these problems，a fault-tolerant control method ofAPF based on component redundancy was proposed. Under the condition of component redundancy，the three-phase six switch APF was reconstructed into three-phase four switch APF. At the same time，the topology ofAPF was analyzed and the data model of eliminating redundancy was formed. Based on the Lyapunov stability theorem，the current link control strategy and controller were designed，and the voltage was stabilized in the expected value range by proportional integral，and finally the fault-tolerant control of active power filter was realized. The simulation results also show that the proposed method can effectively improve the execution efficiency and fault-tolerant rate，and effectively reduce the fault-tolerant control error.

      Key words: component redundancy；active power filter （APF）；fault-tolerant control；mathematical model