A generalized open-end winding conversion system using flying capacitor cells.

Highlights • The system is easily generalized to any number of levels. • All switching devices present the same blocking voltage. • The energy storage of the flying capacitors is lower than in a Δ/ Y system. • A modulation technique with optimized harmonics and losses can be used. Abstract Over the years, industrial processes, renewable energy systems and electrification of transport systems have been pushing power electronics equipment towards higher power ratings, quality and faster dynamics. In this context, several multilevel converter structures were developed and became popular, such as neutral-point-clamped, flying capacitor and cascaded half-bridge. This paper presents a generalized n -level converter using the multicell flying capacitor structure in an open-end winding configuration. A mathematical analysis shows that the proposed system presents the same output voltages as a traditional Δ/ Y structure, but with less energy storage in the flying capacitors. The correlation with the traditional structure allows the use of an optimized modulation technique developed for the flying capacitor converter. It results in a voltage output with optimized harmonics, keeps the losses evenly distributed among the switching devices, and balances the voltages in the flying capacitors. Experimental results from a three-level conversion system and simulation results from a five-level structure demonstrate the features of the proposed topology. [ABSTRACT FROM AUTHOR]