Investigation of modulation strategies for three-phase three-level rectifier applications

This paper presents a comparative research for different pulse-width modulation schemes to achieve the power-factor correction (PFC) function for a three-phase three-level boost rectifier. It uses three bidirectional switches connected to the common capacitive center point of the DC bus that allows the three-level operation and a low blocking-voltage stress on the power switches, and has the advantages of lower per-unit current ratings of the switching devices. The study also explored the impacts of the two DC voltage control and load unbalanced situation. Three modulation strategies are compared, and the validity of the proposed method is confirmed by simulation and experimental results through a 1kW prototype.