Analytical determination of conduction power losses for active neutral-point-clamped multilevel converter

Active neutral-point-clamped (ANPC) converter is a well-known type of multilevel converter which is commercially available in high-power medium-voltage drive market. Since conduction loss investigation is advantageous in design phase of converters, this paper presents an analytical approach to calculate and investigate conduction power loss in ANPC converter. First, rms and average currents of IGBTs and anti-parallel diodes are analytically calculated by considering the associated duty cycle of each IGBT and diode, converter modulation index, load current, and load power factor. Numerical results of the derived analytical equations to calculate rms and average current of IGBT/diode are compared against simulation results and experimental measurements. All simulation, analytic, and experimental results agree well with each other which substantiate derived closed-form equations. Afterwards, obtained equations for rms and average current computations are utilized to calculate conduction power losses in a 12.4MVA 3.3kV 9-level (line-to-line) ANPC converter analytically. For this purpose, a 2.5kV 1.5kA IGBT module from ABB is considered as a power switch.