The active power filter (APF) is usually based on three-phase six-switch topology. In order to improve its reliability

a three-phase four-switch redundancy fault-tolerant APF topology is proposed. For an open-circuit fault in the three-phase six-switch APF

a fault identification method based on power device voltage change is proposed. By studying the relation between harmonic detection APF compensation algorithm and supply current tracking APF compensation algorithm

it is pointed out that the latter is more suitable for fault-tolerant APF application. Based on the mathematical model of three-phase four-switch APF

a direct current (DC) bus midpoint voltage feed-forward compensation algorithm is presented to compensate for the side-effect on output imbalance; if energy storage is configured on the DC side

APF active power regulation is also available. The APF fault tolerant switching control strategy is proposed. Based on a three-phase four-switch APF platform

the effectiveness of the proposed method is verified by experiment.