Loss balancing for Active-NPC and Active-Stacked-NPC multilevel converters

The paper is focused on the numerical calculation of total losses in each power device of 3L-ANPC (Active-NPC) and 3L-ASNPC (Active-Stacked-NPC) multilevel converters in a STATCOM application. Due to the symmetry of the structures the conduction and switching losses are calculated only for half of power devices. The modulation functions and the conduction/switching intervals are elaborated in order to calculate the total losses. These are specific for each power device depending on the structure's type and on the PWM strategy. The obtained results for conduction currents (average and RMS values) are validated using PSIM simulations.