Five-level T-type NPC PFC rectifier based on multistate switching cell

This paper presents a proof of concept of a new converter cell named T-type multistate switching cell (TT-MSSC). The proposed cell was derived from the three-phase current fed DC-DC Push-Pull converter with NPC output rectifier and can provide both AC-DC and DC-AC conversions for single-phase, three-phase or multi-phase configurations. Based on the proposed cell, a single-phase unidirectional converter is proposed which provides the following features: power factor correction, current sharing through devices, symmetrical voltage division across semiconductors, inductor current ripple with twice switching frequency, and five level voltage formation between ground point and common point of the autotransformer. To verify the operation principle, a prototype with the input voltage Vi = 220 V (rms), output voltage Vo = 800 V, and output power Po = 1 kW was implemented and tested in laboratory.