Design and comparison of 4.16 kV neutral point clamped, flying capacitor and series connected H-bridge multi-level converters

This paper describes the design of a (4 kV, 4.16 MVA) three-level neutral point clamped-, three-level flying capacitor-, four-level flying capacitor-and nine-level series connected H-bridge voltage source converter on the basis of state-of-the-art 6.5 kV, 4.5 kV, 3.3 kV and 1.7 kV IGBTs. The semiconductor loss distribution and the design of semiconductors and passive components are compared for a medium switching frequency assuming a constant converter efficiency of about 99%. To evaluate the converter characteristics in high switching frequency applications a second comparison is realized for the maximum switching frequencies assuming a constant expense of semiconductors in all converters.