A Generic Switching State-Space Model for Modular Multilevel Cascade Converters

This paper presents a generic switching state-space model for modular multilevel cascade converters in double-star connection (MMCC-DS) which can either be used with chopper cells (CC; half bridges) or bridge cells (BC; full bridges) and allows to consider arbitrary switch(ing) faults. The output terminals of the MMCC-DS are connected to a general resistive-inductive (RL) load with additional voltage sources in star connection. The model is derived and described in detail by using Kirchhoff's current and voltage laws (KCL, KVL) and allows for currents flowing through the anti-parallel diodes of the active switches in each cell. The model is implemented in Matlab/Simulink 2019b and PLECS for a simulative validation and comparison of the proposed model.