Stability Assessment and Optimization of MMC Energy Balancing for Drive Applications at Standstill Using an Averaging Approach

A new controller design framework for periodic systems is presented and applied to the Modular Multi-level Converter energy balancing. It provides a rigorous stability analysis for the state-of-art averaging control and the approach using constants as reference for the instantaneous energies. An optimized controller with improved performance is derived and verified by simulation and experiment.