Bidirectional modular multilevel PFC rectifier based on cascading full-bridge and interleaving technique suitable for SST applications

This paper presents a bidirectional ac-dc topology based on modular multilevel converter and employing the interleaving concept suitable for solid-state transformer applications. The main features of this topology are derived from the interleaving and the cascading converters concepts, as reduced conduction losses, passive elements operating with effective high frequency, reduced weight and volume, and reduced output high-frequency current ripple. The basic operation of the proposed topology as well as a pulse-width modulation scheme and proper control strategy are described. Simulation results of the proposed converter operating with switching frequency of 2.5 kHz, rated output power of 33.33 kW output voltage 800 V and fed from a 7.96 kV/ 60 Hz ac grid are presented.