A hybird cascade H-bridge seven-level converter for active power filter

In this paper, a three-phase four-wire shunt active power filter (APF) is studied. In order to reduce voltage stress of power devices and improve the performance and practicality of APF in high voltage and capacity occasions, a hybrid cascade H-bridge seven-level converter is adopted as the main circuit of the APF. In system control, DC-link total voltage control is realized by transferring active power between AC and DC side. Meanwhile, a voltage distribution control method is employed which forcefully ensure the ratio of 1:2 between the two DC voltages of cascaded cells without any auxiliary circuit. Finally, simulation and experiment are implemented to verify the correctness of the theory and the results demonstrate an excellent compensation performance of the proposed APF.