Proper choice of flying capacitors based on distinct power dissipation models

Abstract

With the many types of capacitors available, making the correct choice for an AC power application is not that straightforward. Especially in the case of multilevel power converters which rely on a capacitive buffer clamp, an adequate dimensioning of these components is necessary to obtain a higher power per volume rate. This paper discuss the peculiarities concerning the so-called flying capacitors in multi-level power converter structures with nested cells, aiming at an optimal component selection. On the basis of the capacitor current harmonic content under nominal operation, the internal power dissipation is calculated analytically. Experimental measurements confirm the validity of the analysis.