Modeling and Analysis of Shutdown Dynamics in Flying Capacitor Multilevel Converters

Abstract

This work explores the dynamic behavior of the flying capacitor multilevel (FCML) converter during unplanned shutdown. A model for a general N-level FCML converter is developed, which captures capacitor non-linearities, component leakage paths, and body diode behavior. This work highlights how switch voltage ratings may be exceeded during unplanned shutdown, and proposes several mitigation strategies. Using a ten-level FCML converter hardware prototype, the time-domain behavior of the model is verified, and a successful hardware mitigation strategy is demonstrated which ensures safe and rapid converter shutdown.