Using Assignment Figures to evaluate cost functions in predictive inverter control

Abstract

This paper introduces so-called “Assignment Figures” as a tool to evaluate the impact of different cost functions on the resulting switching state patterns for predictive inverter control. These Assignment Figures are derived for two-level voltage source inverters and investigated for different cost function variants, including weighted switching frequency reduction and common-mode voltage reduction. It is shown how this graphical method can be used for selecting appropriate cost functions and for tuning weighting factors.