Mathematical models for analysis of energy quality performance in three-phase four-level NPC converters

Unified analysis technique for energy quality factors estimation of NPC multilevel VSC for energy storage systems

“…The phase potentials can be found using the switching functions of the power semiconductor devices [12]. In general case potential of each phase leg in an N-level NPC converter can be written as follows:…”

“…In case of SVPWM the modulating signal can be represented by using the duty cycles of the switching state vectors [12]. Carrier signals for any modulation strategy can be defined by the reverse trigonometric functions:…”

“…This part presents a set of equations for a computer-aided calculation of the following items: RMS and average currents for power semiconductor devices; instantaneous values of the, phase-to ground voltages; THD and WTHD for the phase voltage. This part is based on the switching functions method [11,12].…”

“…Since the first multilevel mentioning in 1981 a lot of methods and techniques to calculate currents and voltages in a multilevel converter were offered [4][5][6][7][8][9][10][11][12]. Most of them use analytical equations applicable to one specific topology with fixed level number [4] or specified PWM strategy.…”