Stability analysis of multicell converters using Gerschgorin circles

The multicell converter topology possesses a natural voltage balancing property. This paper uses models obtained previously to perform a stability analysis of multicell converters. It uses a generic model in steady-state- and time constant analyses to determine the stability of multicell converters. In this paper stability refers to balanced cell capacitor voltages, whereas instability refers to unbalanced cell capacitor voltages. The stability analysis is performed for both sinusoidal modulation as well as fixed duty-cycle modulation. The model used in the stability analyses in this paper is valid for any modulation method. The conditions that lead to stability of the cell capacitor voltages as well as that leading to instability are presented. Theoretical results are included to verify the presented stability analyses and properties.