Five-level single-leg flying capacitor converter voltage balance dynamics analysis

Abstract

The attractive feature of a flying capacitor converter is the natural voltage balance property. The reported voltage balance dynamics analytical research methods are based on heavy frequency domain transformations (Fourier transform, Bessel functions etc) and are rather algorithmic and difficult to use in an everyday engineering practice. Suggested time domain approach uses stitching of piece-wise analytical solutions for consecutive switching intervals. The small parameter analysis of a five-level single-leg converter yields physically meaningful, simple, and accurate expressions for average voltage balance dynamics giving an in-depth insight into parameters, carrier frequency, and modulation strategy impact for both DC and AC PWM.