A new four-level converter for low and medium voltage applications

The paper presents a new four-level voltage source converter (VSC). Compared to conventional four-level converters, this proposed converter has fewer components and can be used for a higher power density system in low and medium voltage applications. Its principles and advantages are studied in this paper. The effect of various redundant switching states on the voltages of flying capacitors is analyzed. The voltages of flying capacitors can be balanced by selecting proper redundant switching states. A carrier-based pulse width modulation (CBPWM) is used to control the proposed converter. The performance of the converter is investigated and simulated in MATLAB/Simulink as well as on a 5 kVA experimental prototype.