Modeling the Dynamic Behavior of Hybrid-Switched-Capacitor Converters in State Space

A key challenge in operating Hybrid Switched Capacitor (SC) converters, which merge SC architectures with an inductive impedance, arises from the fact that the inductor decouples the SC stage from the output node, which can lead to deviation of the flying capacitor voltages from their nominal voltages. This work presents a method that combines continuous and discrete state-space analysis to model the dynamics (including flying capacitor voltage states) of arbitrary hybrid SC converters with arbitrary operating modes. We will show that in some cases, observed capacitor voltage imbalance in Flying Capacitor Multilevel (FCML) converters can be predicted under assumptions of ideal operation. The periodic steady state of such converters and its stability and uniqueness are determined and verified with a 7-level FCML hardware prototype and compared to results from previous work.