Five-Level Switched-Capacitor Unidirectional Rectifier With Reduced Number of Components

This article proposes a three-phase five-level switched-capacitor unidirectional rectifier. The proposed unidirectional rectifier is derived from a bidirectional five-level active neutral point clamped topology by eliminating four active switches per phase. Even with fewer active switches, five voltage levels can still be synthesized at the input ac side, which leads to reduction of the size and weight of the grid interface filter. Moreover, the proposed unidirectional rectifier enables the self-voltage regulation of floating capacitors, reducing the complexity of the control system, and also allows the generation of smaller output dc voltages in comparison to conventional boost-type rectifiers. The circuit derivation of the proposed rectifier, as well as its features, operating principles, and control scheme are described in this article. Finally, experimental results for a three-phase 3-kW prototype are presented to demonstrate the feasibility of the proposed structure.